Sensorless vector and direct torque control
Vas, Peter
1998-01-01
This is the first comprehensive book on sensorless high performance a.c. drives. It is essential reading for anyone interested in acquiring a solid background on sensorless torque-controlled drives. It presents a detailed and unified treatment of sensorless vector-controlled and direct-torque controlled drive systems. It also discusses the applications of artificial intelligence to drives. Where possible, space vector theory is used and emphasis is laid on detailed mathematical and physical analysis. Sensorless drive schemes for different types of permanent magnet synchronous motors, synchronous reluctance motors, and induction motors are also presented. These include more than twenty vector drives e.g. five types of MRAS-based vector drives, and eleven types of direct-torque-controlled (DTC) drives, e.g. the ABB DTC drive. However, torque-controlled switched reluctance motor drives are also discussed due to their emerging importance. The book also covers various drive applications using artificial intellige...
Improved Torque Control Performance of Direct Torque Control for 5-Phase Induction Machine
Logan Raj Lourdes Victor Raj
2013-12-01
Full Text Available In this paper, the control of five-phase induction machine using Direct Torque Control (DTC is presented. The general D-Q model of five-phase induction machine is discussed. The de-coupled control of stator flux and electromagnetic torque based on hysteresis controller similar to conventional DTC is applied to maintain the simplicity of the system. Three sets of look-up tables consist of voltage vectors with different amplitude that selects the most optimal voltage vectors according motor operation condition is proposed. This provides excellent torque dynamic control, reduces torque ripple, lower switching frequency (high efficiency and extension of constant torque. Simulation results validate the improvement achieved.
Direct Torque Control of IPMSM to Improve Torque ripple and Efficiency based on Fuzzy Controller
B. Mirzaeian Dehkordi
2012-09-01
Full Text Available In this paper, a stator-flux-reference frame control method is proposed in order to control the speed and torque of an Interior Permanent Magnet Synchronous Machine (IPMSM in different loads condition. Direct Torque Control method (DTC based on Space Vector Modulation (SVM is used for control of IPMSM. In the proposed control method, conventional PI controller is used for controlling the stator flux, and torque of the motor. Also, a fuzzy controller is considered to improve the dynamic performance of DTC technique for speed control. In comparison to the conventional reference flux controller methods, this method, in addition, improves the torque profile of the motor drive. Moreover, it reduces copper losses. Simulation results for a 240V, 120A, 2500rpm, IPMSM confirm the appropriate performances of the method.
DIRECT TORQUE CONTROL FOR INDUCTION MOTOR USING INTELLIGENT TECHNIQUES
R.Toufouti
2007-09-01
Full Text Available In this paper, we propose two approach intelligent techniques of improvement of Direct Torque Control (DTC of Induction motor such as fuzzy logic (FL and artificial neural network (ANN, applied in switching select voltage vector .The comparison with conventional direct torque control (DTC, show that the use of the DTC_FL and DTC_ANN, reduced the torque, stator flux, and current ripples. The validity of the proposed methods is confirmed by the simulative results.
Torque Ripple Reduction in Direct Torque Control Based Induction Motor using Intelligent Controllers
Sudhakar, Ambarapu; Vijaya Kumar, M.
2015-09-01
This paper presents intelligent control scheme together with conventional control scheme to overcome the problems with uncertainties in the structure encountered with classical model based design of induction motor drive based on direct torque control (DTC). It allows high dynamic performance to be obtained with very simple hysteresis control scheme. Direct control of the torque and flux is achieved by proper selection of inverter voltage space vector through a lookup table. This paper also presents the application of intelligent controllers like neural network and fuzzy logic controllers to control induction machines with DTC. Intelligent controllers are used to emulate the state selector of the DTC. With implementation of intelligent controllers the system is also verified and proved to be operated stably with reduced torque ripple. The proposed method validity and effectiveness has been verified by computer simulations using Matlab/Simulink®. These results are compared with the ones obtained with a classical DTC using proportional integral speed controller.
Direct Torque Control With Feedback Linearization for Induction Motor Drives
Lascu, Cristian Vaslie; Jafarzadeh, Saeed; Fadali, Sami M.
2017-01-01
This paper describes a direct-torque-controlled (DTC) induction motor (IM) drive that employs feedback linearization and sliding-mode control (SMC). A new feedback linearization approach is proposed, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude....... This intuitive linear model is used to implement a DTC-type controller that preserves all DTC advantages and eliminates its main drawback, the flux and torque ripple. Robust, fast, and ripple-free control is achieved by using SMC with proportional control in the vicinity of the sliding surface. SMC assures...... robustness as in DTC, while the proportional component eliminates the torque and flux ripple. The torque time response is similar to conventional DTC and the proposed solution is flexible and highly tunable due to the P component. The controller design is presented, and its robust stability is analyzed...
Improved Torque Control Performance in Direct Torque Control using Optimal Switching Vectors
Muhd Zharif Rifqi Zuber Ahmadi
2015-02-01
Full Text Available This paper presents the significant improvement of Direct Torque Control (DTC of 3-phases induction machine using a Cascaded H-Bidge Multilevel Inverter (CHMI. The largest torque ripple and variable switching frequency are known as the major problem founded in DTC of induction motor. As a result, it can diminish the performance induction motor control. Therefore, the conventional 2-level inverter has been replaced with CHMI the in order to increase the performance of the motor either in dynamic or steady-state condition. By using the multilevel inverter, it can produce a more selection of the voltage vectors. Besides that, it can minimize the torque ripple output as well as increase the efficiency by reducing the switching frequency of the inverter. The simulation model of the proposed method has been developed and tested by using Matlab software. Its improvements were also verified via experimental results.
Direct torque control with feedback linearization for induction motor drives
Lascu, Cristian; Jafarzadeh, Saeed; Fadali, Sami M.
2015-01-01
This paper describes a Direct Torque Controlled (DTC) Induction Machine (IM) drive that employs feedback linearization and sliding-mode control. A feedback linearization approach is investigated, which yields a decoupled linear IM model with two state variables: torque and stator flux magnitude...... of the sliding surface. The VSC component assures robustness as in DTC, while the proportional component eliminates the torque and flux ripple. The torque time response is similar to DTC and the proposed solution is flexible and highly tunable due to the proportional controller. The controller design and its...... robust stability analysis are presented. The sliding controller is compared with a linear DTC scheme, and experimental results for a sensorless IM drive validate the proposed solution....
Abdelli, R; Rekioua, D; Rekioua, T
2011-04-01
This paper describes a torque ripple reduction technique with constant switching frequency for direct torque control (DTC) of an induction motor (IM). This method enables a minimum torque ripple control. In order to obtain a constant switching frequency and hence a torque ripple reduction, we propose a control technique for IM. It consists of controlling directly the electromagnetic torque by using a modulated hysteresis controller. The design methodology is based on space vector modulation (SVM) of electrical machines with digital vector control. MATLAB simulations supported with experimental study are used. The simulation and experimental results of this proposed algorithm show an adequate dynamic to IM; however, the research can be extended to include synchronous motors as well. The implementation of the proposed algorithm is described. It doesn't require any PI controller in the torque control loop. The hardware inverter is controlled digitally using a Texas Instruments TMS320F240 digital signal processor (DSP) with composed C codes for generating the required references. The results obtained from simulation and experiments confirmed the feasibility of the proposed strategy compared to the conventional one.
Novel torque ripple minimization algorithm for direct torque control of induction motor drive
LONG Bo; GUO Gui-fang; HAO Xiao-hong; LI Xiao-ning
2009-01-01
To elucidate the principles of notable torque and flux ripple during the steady state of the conventional direct torque control (DTC) of induction machines, the factors of influence torque variation are examined. A new torque ripple minimization algorithm is proposed. The novel method eradicated the torque ripple by imposing the required stator voltage vector in each control cycle. The M and T axial components of the stator voltage are accomplished by measuring the stator flux error and the expected incremental value of the torque at every sampling time. The maximum angle rotation allowed is obtained. Experimental results showed that the proposed method combined with the space vector pulse width modulation(SVPWM) could be implemented in most existing digital drive controllers, offering high performance in both steady and transient states of the induction drives at full speed range. The result of the present work imphes that torque fluctuation could be eliminated by imposing proper stator voltage, and the proposed scheme could not only maintain constant switching frequency for the inverter, but also solve the heating problem and current harmonics in traditional induction motor drives.
Novel Design for Direct Torque Control System of PMSM
HUANG Xu-chao
2013-04-01
Full Text Available Nowadays, with the rapid development of high-performance servo system, The conventional permanent magnet synchronous motor (PMSM Direct Torque Control (DTC system has large torque ripple in low speed which cannot be well adapted to today`s development. The main reason is because the number of voltage vectors provided by the two-level inverter is only six and the relationship between voltage vector and torque is not clear[1-5.10-12]. In this paper, the basic concept of direct torque control of permanent magnet synchronous motor is investigated in order to emphasize the effects produced by a given voltage vector on stator and torque variations in this paper. Modified the voltage sector switching table, a novel DTC scheme for the permanent magnet synchronous motor is proposed which is using a novel three-level inverter. An improvement of the drive performance can be obtained by using the novel DTC scheme. The simulation results showed that the scheme could reduce the torque ripple in low speed and improved the stability of the motor under the condition of keeping the system dynamic performance.
Improved direct torque control of induction motor with dither injection
R K Behera; S P Das
2008-10-01
In this paper, a three-level inverter-fed induction motor drive operating under Direct Torque Control (DTC) is presented. A triangular wave is used as dither signal of minute amplitude (for torque hysteresis band and ﬂux hysteresis band respectively) in the error block. This method minimizes ﬂux and torque ripple in a three-level inverter fed induction motor drive while the dynamic performance is not affected. The optimal value of dither frequency and magnitude is found out under free running condition. The proposed technique reduces torque ripple by 60% (peak to peak) compared to the case without dither injection, results in low acoustic noise and increases the switching frequency of the inverter. A laboratory prototype of the drive system has been developed and the simulation and experimental results are reported.
Design and Comparison Direct Torque Control Techniques for Induction Motors
Blaabjerg, Frede; Kazmierkowski, Marian P.; Zelechowski, Marcin
2005-01-01
In this paper a comparison of two significant control methods of induction motor are presented. The first one is a classical Direct Torque and Flux Control (DTC) and is compared with a scheme, which uses Space Vector Modulator (DTC-SVM). A comparison in respect to dynamic and steady state...
IPMSM Motion-Sensorless Direct Torque and Flux Control
Pitict, Christian Ilie; Andreescu, Gheorghe-Daniel; Blaabjerg, Frede
2005-01-01
The paper presents a rather comprehensive implementation of a wide speed motion-sensorless control of IPMSM drives via direct torque and flux control (DTFC) with space vector modulation (SVM). Signal injection with only one D-module vector filter and phase-locked loop (PLL) observer is used at low...
IPMSM Motion-Sensorless Direct Torque and Flux Control
Pitict, Christian Ilie; Andreescu, Gheorghe-Daniel; Blaabjerg, Frede
2005-01-01
The paper presents a rather comprehensive implementation of a wide speed motion-sensorless control of IPMSM drives via direct torque and flux control (DTFC) with space vector modulation (SVM). Signal injection with only one D-module vector filter and phase-locked loop (PLL) observer is used at low...
STATOR FLUX OPTIMIZATION ON DIRECT TORQUE CONTROL WITH FUZZY LOGIC
Fatih Korkmaz
2012-07-01
Full Text Available The Direct Torque Control (DTC is well known as an effective control technique for high performance drives in a wide variety of industrial applications and conventional DTC technique uses two constant reference value: torque and stator flux. In this paper, fuzzy logic based stator flux optimization technique for DTC drives that has been proposed. The proposed fuzzy logic based stator flux optimizer self-regulates the stator flux reference using induction motor load situation without need of any motor parameters. Simulation studies have been carried out with Matlab/Simulink to compare the proposed system behaviors at vary load conditions. Simulation results show that the performance of the proposed DTC technique has been improved and especially at low-load conditions torque ripple are greatly reduced with respect to the conventional DTC.
Research on Direct Torque Control System Based on Induction Motor
康劲松; 陶生桂; 毛明平
2003-01-01
The mathematic model of direct torque control (DTC) was deduced. Two simulating models based on the MATLAB & SIMULINK were established. The emphasis is focused on study of the performance difference of the DTC system with stator flux hexagon and circle trajectories. The simulation waveforms of flux, torque and current characters with two flux trajectories were given. Experiments were carried out in an AC drive system based on induction motor and two-level inverter. A dual-CPU structure was used and the communication with two CPUs was obtained by a dual-port RAM in this system.
Application of Space Vector Modulation in Direct Torque Control of PMSM
Michal Malek
2008-01-01
Full Text Available The paper deals with an improvement of direct torque control method for permanent magnet synchronous motor drives. Electrical torque distortion of the machine under original direct torque control is relatively high and if proper measures are taken it can be substantially decreased. The proposed solution here is to combine direct torque control with the space vector modulation technique. Such approach can eliminate torque distortion while preserving the simplicity of the original method.
LI Jian; YANG Geng; WANG Huan'gang; XU Wenli
2005-01-01
A torque control scheme for high-performance induction machine drives was developed to over- come some disadvantages of direct torque control (DTC). In the improved DTC method, the stator flux and the torque controllers use variable-structure control theory which does not require information about the rotor speed. Space vector modulation is applied to the voltage source inverter to reduce the torque, stator flux, and current ripples. The digital signal processor-based implementation is described in detail. The experimental results show that the system has good torque and stator flux response with small ripples.
Direct-Torque Neuro-Fuzzy Control of Induction Motor
徐君鹏; CHEN Yan-feng; LI Guo-hou
2007-01-01
Fuzzy systems are currently being used in a wide field of industrial and scientific applications. Since the design and especially the optimization process of fuzzy systems can be very time consuming, it is convenient to have algorithms which construct and optimize them automatically. In order to improve the system stability and raise the response speed, a new control scheme, direct-torque neuro-fuzzy control for induction motor drive, was put forward. The design and tuning procedure have been described. Also, the improved stator flux estimation algorithm, which guarantees eccentric estimated flux has been proposed.
Direct Torque Control for Double Star Induction Motor
LEKHCHINE, SALIMA; BAHI, TAHAR; Soufi, Youcef
2016-01-01
This paper describes a direct torque control (DTC) of dual star induction motor (DSIM). This machine possesses several advantages over conventional three-phase machine and is also known as the six-phase induction machine. The research has been underway for the last two decades to investigate the various issues related to the use of six-phase machine as a potential alternative to the conventional three-phase machine. Though six-phase machines have existed for some time, in the literature very ...
Souha Boukadida
2014-12-01
Full Text Available The conventional Direct Torque Control (DTC is known to produce a quick and robust response in AC drives. However, during steady state, stator flux and electromagnetic torque which results in incorrect speed estimations and acoustical noise. A modified Direct Torque Control (DTC by using Space Vector Modulation (DTC-SVM for induction machine is proposed in this paper. Using this control strategy, the ripples introduced in torque and flux are reduced. This paper presents a novel approach to design and implementation of a high perfromane torque control (DTC-SVM of induction machine using Field Programmable gate array (FPGA.The performance of the proposed control scheme is evaluated through digital simulation using Matlab\\Simulink and Xilinx System Generator. The simulation results are used to verify the effectiveness of the proposed control strategy.
Induction machine Direct Torque Control system based on fuzzy adaptive control
Li, Shi-ping; Yu, Yan; Jiao, Zhen-gang; Gu, Shu-sheng
2009-07-01
Direct Torque Control technology is a high-performance communication control method, it uses the space voltage vector method, and then to the inverter switch state control, to obtain high torque dynamic performance. But none of the switching states is able to generate the exact voltage vector to produce the desired changes in torque and flux in most of the switching instances. This causes a high ripple in torque. To solve this problem, a fuzzy implementation of Direct Torque Control of Induction machine is presented here. Error of stator flux, error of motor electromagnetic torque and position of angle of flux are taken as fuzzy variables. In order to further solve nonlinear problem of variation parameters in direct torque control system, the paper proposes a fuzzy parameter PID adaptive control method which is suitable for the direct torque control of an asynchronous motor. The generation of its fuzzy control is obtained by analyzing and optimizing PID control step response and combining expert's experience. For this reason, it carries out fuzzy work to PID regulator of motor speed to achieve to regulate PID parameters. Therefore the control system gets swifter response velocity, stronger robustness and higher precision of velocity control. The computer simulated results verify the validity of this novel method.
High Performance Direct Torque Control of Induction Motor Drives Using Space Vector Modulation
S. Allirani
2010-11-01
Full Text Available This paper presents a simple approach to design and implement Direct Torque Control technique for voltage source inverter fed induction motor drives. The direct torque control is one of the excellent strategies available for torque control of induction machine. It is considered as an alternative to field oriented control technique. The Direct Torque Control scheme is characterized by the absence of PI regulators, co-ordinate transformations, current regulators and pulse width modulated signal generators. Direct Torque Control allows a good torque control in steady state and transient operating conditions. The direct torque control technique based on space vector modulation and switching table has been developed and presented in this paper.
Simulation of Brushless DC Motor using Direct Torque Control
Kusuma, G.; S. Rukhsana Begum
2014-01-01
This paper deals with modelling of three phases brushless dc motor with MATLAB/SIMULINK software BLDC motor have advantages according to brushless dc motor and induction motor’s. They have improve speed torque charactistics, high efficiency high transient response and small size. It approaches for reducing the torque ripples of BLDC motor using DTC, by using control technique’s ,but present work mainly concentrate on advanced method. The whole drive system is simulated based o...
Tole Sutikno
2011-11-01
Full Text Available Direct Torque Control (DTC has gained popularity for development of advanced motor control due to its simplicity and offers fast instantaneous torque and flux controls. However, the conventional DTC which is based on hysteresis controller has major drawbacks, namely high torque ripple and variable inverter switching frequency. This paper presents an improved switching strategy for reducing flux and torque ripples in DTC of PMSM drives; wherein the torque hysteresis controller and the look-up table used in the conventional DTC are replaced with a constant frequency torque controller (CFTC and an optimized look-up table, respectively. It can be shown that a constant switching frequency is established due to the use of the CFTC while the reduction of torque and flux ripples is achieved mainly because of the selection of optimized voltage vector (i.e. with an optimized look-up table. This paper also will explain the construction of DTC schemes implemented using MATLAB-Simulink blocks. Simulation results were shown that a significant reduction of flux and torque ripples which is about 90% can be achieved through the proposed DTC scheme.
Simulation of Brushless DC Motor using Direct Torque Control
Mrs.G. Kusuma
2014-04-01
Full Text Available This paper deals with modelling of three phases brushless dc motor with MATLAB/SIMULINK software BLDC motor have advantages according to brushless dc motor and induction motor’s. They have improve speed torque charactistics, high efficiency high transient response and small size. It approaches for reducing the torque ripples of BLDC motor using DTC, by using control technique’s ,but present work mainly concentrate on advanced method. The whole drive system is simulated based on the system devices, BLDC motor source inverter, space vector modulation.
Fatih Korkmaz
2013-11-01
Full Text Available The induction motors are indispensable motor types for industrial applications due to its wellknown advantages. Therefore, many kind of control scheme are proposed for induction motors over the past years and direct torque control has gained great importance inside of them due to fast dynamic torque response behavior and simple control structure. This paper suggests a new approach on the direct torque controlled induction motors, Fuzzy logic based space vector modulation, to overcome disadvantages of conventional direct torque control like high torque ripple. In the proposed approach, optimum switching states are calculated by fuzzy logic controller and applied by space vector pulse width modulator to voltage source inverter. In order to test and compare the proposed DTC scheme with conventional DTC scheme simulations, in Matlab/Simulink, have been carried out in different speed and load conditions. The simulation results showed that a significant improvement in the dynamic torque and speed responses when compared to the conventional DTC scheme.
ZHOU Yangzhong; HU Yuwen; HUANG Wenxin; ZHONG Tianyun
2007-01-01
The electrically excited synchronous motor (ESM)has typically small synchronous inductance values and quite low transient values because of the damper windings mounted on the rotor.Therefore,the torque and stator flux linkage ripples are high in the direct torque control(DTC)drive of the ESM with a torque and flux linkage hysteresis controller (basic DTC).A DTC scheme with space vector modulation(SVM)for the ESM was investigated in this paper.It is based on the compensation of the stator flux linkage vector error using the space vector modulation in order to decrease the torque and flux linkage ripples and produce fixed switching frequency under the principle that the torque is controlled by the torque angle in the ESM.Compared with the basic DTC,the results of the simulation and experiment show that the torque and flux linkage rippies are reduced,the maximum current value is decreased during the startup,and the current distortion is much smaller in the steady-state under the SVM-DTC.The field-weakening control is incorporated with the SVM-DTC successfully.
A. S. Koval
2008-01-01
Full Text Available In the article problems of frequency properties research for electric drive system with direct torque control and pulse width modulator are described. The mathematical description of elevator is present. Simplified mathematical description of direct torque control - pulse width modulator electric drive system is shown. Transfer functions for torque and speed loops are determined. Logarithmic frequency characteristics are computed. Damping properties of elevator drive system are estimated.
FPGA-Based Implementation Direct Torque Control of Induction Motor
Saber Krim
2015-02-01
Full Text Available This paper proposes a digital implementation of the direct torque control (DTC of an Induction Motor (IM with an observation strategy on the Field Programmable Gate Array (FPGA. The hardware solution based on the FPGA is caracterised by fast processing speed due to the parallel processing. In this study the FPGA is used to overcome the limitation of the software solutions (Digital Signal Processor (DSP and Microcontroller. Also, the DTC of IM has many drawbacks such as for example; The open loop pure integration has from the problems of integration especially at the low speed and the variation of the stator resistance due to the temperature. To tackle these problems we use the Sliding Mode Observer (SMO. This observer is used estimate the stator flux, the stator current and the stator resistance. The hardware implementation method is based on Xilinx System Generator (XSG which a modeling tool developed by Xilinx for the design of implemented systems on FPGA; from the design of the DTC with SMO from XSG we can automatically generate the VHDL code. The model of the DTC with SMO has been designed and simulated using XSG blocks, synthesized with Xilinx ISE 12.4 tool and implemented on Xilinx Virtex-V FPGA.
A Model of FPGA-based Direct Torque Controller
Auzani Jidin
2013-02-01
Full Text Available This paper presents a generic model of a fully FPGA-based direct torque controller. This model is developed using two’s-complement fixed-point format approaches, in register-transfer-level (RTL VHDL abstraction for minimizing calculation errors and consuming hardware resource usage. Therefore, the model is universal and can be implemented for all FPGA types. The model is prepared for fast computation, without using of CORDIC algorithm, a soft-core CPU, a transformation from Cartesian-to-polar coordinates, and without the help of third-party applications. To get simpler implementation and fast computation, several methods were introduced: i the backward-Euler approach to calculate the discrete-integration operation of stator flux, ii the modified non-restoring method to calculate complicated square-root operation of stator flux, iii a new sector analysis method. The design, which was coded in synthesizable VHDL in RTL abstraction for implementation on Altera DE2-board has produced very-precise calculations, with minimal error when being compared to MATLAB/Simulink double-precision calculation.
Direct Torque Control of a Small Wind Turbine with a Sliding-Mode Speed Controller
Sri Lal Senanayaka, Jagath; Karimi, Hamid Reza; Robbersmyr, Kjell G.
2016-09-01
In this paper. the method of direct torque control in the presence of a sliding-mode speed controller is proposed for a small wind turbine being used in water heating applications. This concept and control system design can be expanded to grid connected or off-grid applications. Direct torque control of electrical machines has shown several advantages including very fast dynamics torque control over field-oriented control. Moreover. the torque and flux controllers in the direct torque control algorithms are based on hvsteretic controllers which are nonlinear. In the presence of a sliding-mode speed control. a nonlinear control system can be constructed which is matched for AC/DC conversion of the converter that gives fast responses with low overshoots. The main control objectives of the proposed small wind turbine can be maximum power point tracking and soft-stall power control. This small wind turbine consists of permanent magnet synchronous generator and external wind speed. and rotor speed measurements are not required for the system. However. a sensor is needed to detect the rated wind speed overpass events to activate proper speed references for the wind turbine. Based on the low-cost design requirement of small wind turbines. an available wind speed sensor can be modified. or a new sensor can be designed to get the required measurement. The simulation results will be provided to illustrate the excellent performance of the closed-loop control system in entire wind speed range (4-25 m/s).
Elhadj BOUNADJA
2016-07-01
Full Text Available The present work examines a direct torque control strategy using a high order sliding mode controllers of a doubly-fed induction generator (DFIG incorporated in a wind energy conversion system and working in saturated state. This research is carried out to reach two main objectives. Firstly, in order to introduce some accuracy for the calculation of DFIG performances, an accurate model considering magnetic saturation effect is developed. The second objective is to achieve a robust control of DFIG based wind turbine. For this purpose, a Direct Torque Control (DTC combined with a High Order Sliding Mode Control (HOSMC is applied to the DFIG rotor side converter. Conventionally, the direct torque control having hysteresis comparators possesses major flux and torque ripples at steady-state and moreover the switching frequency varies on a large range. The new DTC method gives a perfect decoupling between the flux and the torque. It also reduces ripples in these grandeurs. Finally, simulated results show, accurate dynamic performances, faster transient responses and more robust control are achieved.
Taib, Nabil; Francois, Bruno
2010-01-01
A few papers have been interested by the fixed switching frequency direct torque control fed by direct matrix converters, where we can find just the use of direct torque controlled space vector modulated method. In this present paper, we present an improved method used for a fixed switching frequency direct torque control (DTC) using a direct matrix converter (DMC). This method is characterized by a simple structure, a fixed switching frequency which causes minimal torque ripple and a unity input power factor. Using this strategy, we combine the direct matrix converters advantages with those of direct torque control (DTC) schemes. The used technique for constant frequency is combined with the input current space vector to create the switching table of direct matrix converter (DMC). Simulation results clearly demonstrate a better dynamic and steady state performances of the proposed method.
Zelechowski, M.; Kazmierkowski, M.P.; Blaabjerg, Frede
2005-01-01
In this paper two different methods of PI controllers for direct torque controlled-space vector modulated induction motor drives have been studied. The first one is simple method based only on symmetric optimum criterion. The second approach takes into account the full model of induction motor in...
Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede
2002-01-01
DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...
Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede
2002-01-01
DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...
A Novel Direct Torque Control Permanent Magnet Synchronous Motor Drive used in Electrical Vehicle
Yaohua Li
2011-10-01
Full Text Available In this paper, a modified direct torque control (DTC scheme for permanent magnet synchronous motor (PMSM is investigated, which enables low torque ripple by using an improved voltage vector selection strategy instead of switching table used in conventional DTC. Based on the control of stator flux, torque angle and torque, voltage vector selection strategy of PMSM DTC drive is proposed. In the proposed voltage vector selection strategy, the applied voltage vector is determined according to outputs of hysteresis comparators for stator flux and torque, angular position of stator flux and torque angle, which is finally synthesized by space vector modulation (SVM. Modeling and experimental results for an interior PMSM used in Honda Civic 06My Hybrid electrical vehicle are given. Simulation and experimental results show torque ripple is reduced and the total harmonics of stator current is decreased when compared those of conventional DTC. And a fixed switching frequency is obtained with the help of SVM. In addition, the proposed DTC doesn’t need any additional PI controller, which maintains the simplicity in conventional DTC. Keywords: direct torque control, permanent magnet synchronous motor, electrical vehicle, torque ripple, switching frequency
Vinay KUMAR
2011-06-01
Full Text Available This paper proposes an algorithm for direct flux and torque controlled three phase induction motor drive systems. This method is based on control of slip speed and decoupled between amplitude and angle of reference stator flux for determining required stator voltage vector. In this proposes model, integrator unit is not required to generate the reference stator flux angle for calculating required stator voltage vector, hence it eliminates the initial values problems in real time. Within the given sampling time, flux as well as torque errors are controlled by stator voltage vector which is evaluated from reference stator flux. The direct torque control is achieved by reference stator flux angle which is generates from instantaneous slip speed angular frequency and stator flux angular frequency. The amplitude of the reference stator flux is kept constant at rated value. This technique gives better performance in three-phase induction motor than conventional technique. Simulation results for 3hp induction motor drive, for both proposed and conventional techniques, are presented and compared. From the results it is found that the stator current, flux linkage and torque ripples are decreased with proposed technique.
FENG Yi; HUANG Shu-huai; LI Jun-chao; XIONG Xiao-hong
2009-01-01
Fast response and stable torque output are crucial to the performance of electric screw presses. This paper describes the design of a direct torque control (DTC) system for speeding up torque response and reducing the starting current of electric screw presses and its application to the J58K series of numerical control electric screw presses with a dual-motor drive. The DTC drive system encompasses speed control, torque reference control, and switching frequency control. Comparison of the DTC duaI-AC induction motor drive with corresponding AC servo motor drive showed that for the J58K-315 electric screw press, the DTC drive system attains a higher maximum speed (786 r/min) within a shorter time (1.13 s) during a 250 mm stroke and undergoes smaller rise in temperature (42.0 ℃) in the motor after running for 2 h at a 12 min strike fi'equency than the AC servo motor drive does (751 r/min within 1.19 s, and 50.6 ℃ rise). Moreover, the DTC AC induction motor drive, with no need for a tachometer or position encoder to feed back the speed or position of the motor shaft, enjoys increased reliability in a strong-shock work environment.
An Observing Method for Flux and Speed with Direct Torque Control
祝龙记; 王汝琳
2004-01-01
An observing method for stator flux and rotor flux is presented. Based on the proposed flux observing method, a novel speed estimator has been designed. At last, the speed estimator combined with the flux observing is applied in the direct torque control system without speed sensor. The simulation results show that these methods can improve the accuracy of speed observing and the low speed performance of direct torque control system, and strengthen the robustness of system.
Nandakumar Sundararaju
2014-05-01
Full Text Available This paper proposes novel hybrid asymmetric space vector modulation technique for inverter operated direct torque control induction motor drive. The hybridization process is performed by the combination of continuous asymmetric space vector modulation pulse width technique (ASVPWM and fuzzy operated discontinuous ASVPWM technique. Combination process is based on pulse mismatching technique. Pulse mismatching technique helps to reduce the active region of the switch. Finally, optimal pulses are applied to control the inverter. The optimal hybrid pulse condense switching losses of the inverter and also improves the operating performance of the direct torque control (DTC based drive system like smooth dynamic response in speed reversal, minimum torque error, settling time of speed. Simulation results of proposed hybrid asymmetric space vector pulse width modulation technique to direct torque control (HASVPWM-DTC approach has been carried out by using Matlab-Simulink environment.
Direct Torque Control of Sensorless Induction Motor Drives: A Sliding-Mode Approach
Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede
2004-01-01
-vector pulsewidth modulation is proposed for induction motor sensorless drives. The DTC transient merits and robustness are preserved and the steady-state behaviour is improved by reducing the torque and flux pulsations. A sliding-mode observer using a dual reference frame motor model is introduced and tested......Direct torque control (DTC) is known to produce fast response and robust control in ac adjustable-speed drives. However, in the steady-state operation, notable torque, flux, and current pulsations occur. A new, direct torque and flux control strategy based on variable-structure control and space....... Simulations and comparative experimental results with the proposed control scheme, versus classic DTC, are presented. Very-low-speed sensorless operation (3 r/min) is demonstrated....
Direct Instantaneous Torque Control of 4 Phase 8/6 Switched Reluctance Motor
Srinivas Pratapgiri
2011-10-01
Full Text Available The applications of Switched Reluctance Motor Drives has increased in the recent past because of advantages like simple structure, no rotor winding, high torque to weight ratio, adaptability to harsh environments like coal mining etc. But the main disadvantage is that torque ripple is high because of the double saliency. This paper presents a high dynamic control technique called Direct Instantaneous Torque Control (DITC where in the torque is maintained within a hysteresis band by changing the switching states of the phases between 1, 0 or -1.Thus torque ripple minimization is an inherent property of DITC. DITC based SRM drive is simulated in MATLAB/SIMULINK environment and results are discussed elaborately
Direct torque control via feedback linearization for permanent magnet synchronous motor drives
Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede
2012-01-01
The paper describes a direct torque controlled (DTC) permanent magnet synchronous motor (PMSM) drive that employs feedback linearization and uses sliding-mode and linear controllers. We introduce a new feedback linearization approach that yields a decoupled linear PMSM model with two state...... variables, the torque and the square of stator flux magnitude. This linear model is intuitive and allows the implementation of DTC-type controllers that preserve all DTC advantages and eliminate its main drawback, the flux and torque ripple. Next, we investigate two controllers for toque and flux....... A variable structure controller (VSC) which is robust, fast, and produces low-ripple control is compared with a linear-DTC scheme which is ripple free. The torque time response is similar to a conventional DTC drive and the proposed solutions are flexible and highly tunable. We present the controller design...
Improving the performance of hysteresis direct torque control of IPMSM using active ﬁlter topology
Kayhan Gulez; Ali Ahmed Adam; Halit Pastaci
2006-06-01
This paper describes an active ﬁlter topology to improve the performance of hysteresis direct torque control (HDTC) of interior permanent magnet synchronous motor (IPMSM). The ﬁlter topology consists of an active ﬁlter and two RLC ﬁlters, and is connected to the main power circuit through a 1:1 transformer. The active ﬁlter is characterized by detecting the harmonics in the motor phase voltages and injecting equivalent harmonic voltages to produce almost sinusoidal voltage waveform to the motor terminals. The active ﬁlter uses hysteresis voltage controller while the motor main circuit uses hysteresis direct torque control. The simulation results of this combined control structure show considerable torque ripple reduction in the steady state range and adequate dynamic torque performance as well as considerable harmonic voltage and EMI noise reduction.
A DSP-based discrete space vector modulation direct torque control of sensorless induction machines
Khoucha, F.; Marouani, K.; Kheloui, A.; Aliouane, K.
2004-07-01
In this paper, we present a Direct Torque Control scheme of an induction motor operating without speed sensor. The estimation of the stator flux and the rotor speed is performed by an adaptive observer. In order to reduce the torque, flux, current and speed ripple a Discrete Space Vector Modulation (DSVM-DTC) strategy is implemented using a DSP-based hardware. To illustrate the performances of this control scheme, experimental results are presented. (author)
New concept of direct torque neuro-fuzzy control for induction motor drives. Simulation study
Grabowski, P.Z. [Institute of Control and Industrial Electronics, Warsaw University of Technology, Warsaw (Poland)
1997-12-31
This paper presents a new control strategy in the discrete Direct Torque Control (DTC) based on neuro-fuzzy structure. Two schemes are proposed: neuro-fuzzy switching times calculator and neuro-fuzzy incremental controller with space vector modulator. These control strategies guarantee very good dynamic and steady-states characteristics, with very low sampling time and constant switching frequency. The proposed techniques are verified by simulation study of the whole drive system and results are compared with conventional discrete Direct Torque Control method. (orig.) 18 refs.
Effects of Direct Torque Control Switching Strategies on Common Voltage and Bearing Current
Mohammad Taghi Sadeghzadeh
2012-04-01
Full Text Available Bearing current sininduction motorsare considered a sone of the most damaging factors. Induced shaft voltage through the parasitic capacitors cause this type of current. Inthispaper,given the increasing importance of direct torque control of induction motorin industry, various switching tables are assessed in order to ensure the lowest common voltage while maintaining the performance characteristics of the drive. Finally best switching table based on the minimum CMV, less torque rippleand better quality out put reference tracking is proposed.
Direct Torque Control of Induction Motor Drive Fed from a Photovoltaic Multilevel Inverter
Mahrous Ahmed
2014-09-01
Full Text Available This paper presents Direct Torque Control (DTC using Space Vector Modulation (SVM for an induction motor drive fed from a photovoltaic multilevel inverter (PV-MLI. The system consists of two main parts PV DC power supply (PVDC and MLI. The PVDC is used to generate DC isolated sources with certain ratios suitable for the adopted MLI. Beside the hardware system, the control system which uses the torque and speed estimation to control the load angle and to obtain the appropriate flux vector trajectory from which the voltage vector is directly derived based on direct torque control methods. The voltage vector is then generated by a hybrid multilevel inverter by employing space vector modulation (SVM. The inverter high quality output voltage which leads to a high quality IM performances. Besides, the MLI switching losses is very low due to most of the power cell switches are operating at nearly fundamental frequency. Some selected simulation results are presented for system validation.
High-performance adaptive intelligent Direct Torque Control schemes for induction motor drives
Vasudevan M.
2005-01-01
Full Text Available This paper presents a detailed comparison between viable adaptive intelligent torque control strategies of induction motor, emphasizing advantages and disadvantages. The scope of this paper is to choose an adaptive intelligent controller for induction motor drive proposed for high performance applications. Induction motors are characterized by complex, highly non-linear, time varying dynamics, inaccessibility of some states and output for measurements and hence can be considered as a challenging engineering problem. The advent of torque and flux control techniques have partially solved induction motor control problems, because they are sensitive to drive parameter variations and performance may deteriorate if conventional controllers are used. Intelligent controllers are considered as potential candidates for such an application. In this paper, the performance of the various sensor less intelligent Direct Torque Control (DTC techniques of Induction motor such as neural network, fuzzy and genetic algorithm based torque controllers are evaluated. Adaptive intelligent techniques are applied to achieve high performance decoupled flux and torque control. This paper contributes: i Development of Neural network algorithm for state selection in DTC; ii Development of new algorithm for state selection using Genetic algorithm principle; and iii Development of Fuzzy based DTC. Simulations have been performed using the trained state selector neural network instead of conventional DTC and Fuzzy controller instead of conventional DTC controller. The results show agreement with those of the conventional DTC.
Sliding mode pulse-width modulation technique for direct torque controlled induction motor drive
Bounadja, M.; Belarbi, A. W.; Belmadani, B.
2010-05-01
This paper presents a novel pulse-width modulation technique based sliding mode approach for direct torque control of an induction machine drive. Methodology begins with a sliding mode control of machine's torque and stator flux to generate the reference voltage vector and to reduce parameters sensitivity. Then, the switching control of the three-phase inverter is developed using sliding mode concept to make the system tracking reference voltage inputs. The main features of the proposed methodologies are the high tracking accuracy and the much easier implementation compared to the space vector modulation. Simulations are carried out to confirm the effectiveness of proposed control algorithms.
Direct Torque Control for Three-Level Neutral Point Clamped Inverter-Fed Induction Motor Drive
M. K. Sahu
2012-04-01
Full Text Available Direct torque control (DTC is a control technique in AC drive systems to obtain high performance torque control. The classical DTC drive contains a pair of hysteresis comparators and suffers from variable switching frequency and high torque ripple. These problems can be solved by using space vector depending on the reference torque and flux. In this paper the space vector modulation technique is applied to the three-level Neutral Point Clamped (NPC inverter control in the proposed DTC-based induction motor drive system, resulting to a significant reduce of torque ripple. Three-level neutral point clamped inverters have been widely used in medium voltage applications. This type of inverters have several advantages over standard two-level VSI, such as greater number of levels in the output voltage waveforms, less harmonic distortion in voltage and current waveforms and lower switching frequencies. This paper emphasizes the derivation of switching states using the Space Vector Pulse Width Modulation (SVPWM technique. The control scheme is implemented using Matlab/Simulink. Experimental results using dSPACE validate the steady-state and the dynamic performance of the proposed control strategy.
Direct Torque Control Induction Motor Drive with Improved Flux Response
Bhoopendra Singh
2012-01-01
Full Text Available Accurate flux estimation and control of stator flux by the flux control loop is the determining factor in effective implementation of DTC algorithm. In this paper a comparison of voltage-model-based flux estimation techniques for flux response improvement is carried out. The effectiveness of these methods is judged on the basis of Root Mean Square Flux Error (RMSFE, Total Harmonic Distortion (THD of stator current, and dynamic flux response. The theoretical aspects of these methods are discussed and a comparative analysis is provided with emphasis on digital signal processor (DSP based controller implementation. The effectiveness of the proposed flux estimation algorithm is investigated through simulation and experimentally validated on a test drive.
An improved direct torque controller applied to an electric vehicle
Miguel Durán
2014-01-01
Full Text Available Este artículo presenta la estructura básica, el modelo y el diseño de un controlador de par para un vehículo eléctrico (EV. El EV propuesto es el resultado de la conversión de un vehículo convencional a un vehículo eléctrico, donde el sistema de tracción original basado en un motor de combustión interna es remplazado por un sistema de tracción eléctrica. El controlador está basado en la técnica de control directo de par (DTC más un término que compensa la caída de voltaje en los devanados del estator del motor de inducción (IM. Con el fin de obtener una frecuencia de conmutación constante se utiliza la técnica de modulación PWM vectorial para generar los pulsos del inversor. Se presentan los resultados de simulación para probar el desempeño de la estrategia de control propuesta, la cual es comparada con el esquema de DTC convencional.
Design and Modeling Improved Direct Torque Control of Induction Motor Drive
Omid Moradi
2014-07-01
Full Text Available This paper studies most commonly used electric driving method of induction motors (IM. Direct torque control (DTC have been widely commercialized in induction motor drives, with each being favored by its supporters. In this paper, the dynamic performance of these drives for an electric vehicle application is examined, and sensitivities to parameter variations affecting this dynamic performance are explored by jacobian matrix in which the sensitivities of torque, speed, and other desired variables or outputs are estimated relative to change in motor parameters. Key performance measures include torque and speed transients. The switching scheme of these drive is a switching table. Both the overshoot and the settling time of DTC are really small
Jovanovic, Milutin; Levi, Emil; Yu, James
2006-01-01
Presents the experimental verification of a new sensor-less control algorithm for direct torque (and flux) control (DTC) of the BDFRM in low variable frequency applications (e.g. wind energy conversion systems) where the low cost potential of the machine can be best exploited by using partially-rated power electronics. Brings a significant contribution to knowledge in the subject field as the proposed scheme has many important advantages over its counterparts in the target applications. Repre...
A novel speed sensor-less direct torque control system for mining locomotive haulage
马宪民
2002-01-01
A novel speed sensor-less direct torque control induction motor drive system for the mining locomotive haulage is presented in the paper. Rotor speed identification is based on the model reference adaptive control theory with neural network using back propagation algorithm. The system is implemented using a real-time TMS320F240 digital signal processor. The simulation study and experiment results indicate that the suggested system has good performance.
Active Speed Compensation Method of Direct Torque Control System and Stability Analysis
Rui Li
2015-02-01
Full Text Available By analyzing characteristics of the DTC (direct torque control system in electrical driving system, a shortcoming of the classical DTC method is to point out that it is unable to decouple the mutual interference between torque and speed, so that when a running asynchronous motor subjected to an instantaneous impact load, rotor speed and its deviation appears excessive fluctuations that can not be quickly restored to the initial set value. In this research, under conditions that without sensors for measuring load torque and rotor speed, to an electrical drive systems contains DTC devices, a novel ASCC (active speed compensation control method is proposed based on ADRC (active disturbance rejection control theory, on account of DTC model of asynchronous motor, a multiobjective observer is designed to regulate both the speed and the torque, and a proof of asymptotic stability that related this new control systems with the observer is made by theoretical deduction. Finally stimulating results show that this method can overcome the shortcomings of classical DTC system and greatly enhance the ability of the high-speed driving system to deal with unexpected impact loads.
S. Priya
2013-02-01
Full Text Available Direct torque control of a 3 phase squirrel cage Induction motor though offers a good dynamic response and is free from dynamic coordinate transformation has a major disadvantage of producing rippled torque which degrades the performance of entire drive system. A scheme is proposed in this study which employs seven levels Neutral point clamped inverter which helps in alleviating the torque disturbances. The control scheme for the proposed method is described in this study and the simulation results are reported to demonstrate its effectiveness.
Flux observer algorithms for direct torque control of brushless doubly-fed reluctance machines
Chaal, Hamza; Jovanovic, Milutin
2009-01-01
Direct Torque Control (DTC) has been extensively researched and applied to most AC machines during the last two decades. Its first application to the Brushless Doubly-Fed Reluctance Machine (BDFRM), a promising cost-effective candidate for drive and generator systems with limited variable speed ranges (such as large pumps or wind turbines), has only been reported a few years ago. However, the original DTC scheme has experienced flux estimation problems and compromised performance under the ma...
BELMADANI, B.
2009-06-01
Full Text Available This paper proposes the design and implementation of a novel direct torque controlled induction machine drive system. The control system enjoys the advantages of stator vector control and conventional direct torque control and avoids some of the implementation difficulties of either of the two control methods. The stator vector control principal is used to keep constant the amplitude of stator flux vector at rated value, and to develop the relationship between the machine torque and the rotating speed of the stator flux vector. Thus, the machine torque can be regulated to generate the stator angular speed, which becomes a command signal and permits to overcome the problem of its estimation. Furthermore, with the combined control methods, the reference stator voltage vector can be generated and proportional-integral controllers and space vector modulation technique can be used to obtain fixed switching frequency and low torque ripple. Simulation experiments results indicate that, with the proposed scheme, a precise control of the stator flux and machine torque can be achieved. Compared to conventional direct torque control, presented method is easily implemented, and the steady performances of ripples of both torque and flux are considerably improved.
Lascu, Christian; Boldea, Ion; Blaabjerg, Frede
2004-01-01
A family of variable-structure controllers for induction machine drives is presented, in which the principles of direct torque control (DTC), variable-structure control (VSC) and space-vector pulsewidth modulation are combined to ensure high-performance operation, both in the steady state and under...
Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems
Preindl, Matthias; Schaltz, Erik
2010-01-01
behaviour. It compensates the load torque influence on the speed control setting a feed forward torque value, i.e. current reference value. The benefits are twice. The speed controller reaches immediately the speed reference value avoiding offsets which must be compensated by the weak integrator. Moreover......, a better response to load torque variations which are detected and compensated leading to small speed variations is obtained....
Direct Torque Control of Sensorless Induction Machine Drives: A Two-Stage Kalman Filter Approach
Jinliang Zhang
2015-01-01
Full Text Available Extended Kalman filter (EKF has been widely applied for sensorless direct torque control (DTC in induction machines (IMs. One key problem associated with EKF is that the estimator suffers from computational burden and numerical problems resulting from high order mathematical models. To reduce the computational cost, a two-stage extended Kalman filter (TEKF based solution is presented for closed-loop stator flux, speed, and torque estimation of IM to achieve sensorless DTC-SVM operations in this paper. The novel observer can be similarly derived as the optimal two-stage Kalman filter (TKF which has been proposed by several researchers. Compared to a straightforward implementation of a conventional EKF, the TEKF estimator can reduce the number of arithmetic operations. Simulation and experimental results verify the performance of the proposed TEKF estimator for DTC of IMs.
Application of neural networks for permanent magnet synchronous motor direct torque control
Zhang Chunmei; Liu Heping; Chen Shujin; Wang Fangjun
2008-01-01
Neural networks require a lot of training to understand the model of a plant or a process. Issues such as learning speed, stability, and weight convergence remain as areas of research and comparison of many training algorithms. The application of neural networks to control interior permanent magnet synchronous motor using direct torque control (DTC) is discussed. A neural network is used to emulate the state selector of the DTC. The neural networks used are the back-propagation and radial basis function. To reduce the training patterns and increase the execution speed of the training process, the inputs of switching table are converted to digital signals, i.e., one bit represent the flux error, one bit the torque error, and three bits the region of stator flux. Computer simulations of the motor and neural-network system using the two approaches are presented and compared. Discussions about the back-propagation and radial basis function as the most promising training techniques are presented, giving its advantages and disadvantages. The system using back-propagation and radial basis function networks controller has quick parallel speed and high torque response.
Simulation study on the starting characteristics of a kind of improved direct torque control system
YE Jin-jiao; MENG Qing-chun; GUO Rui
2004-01-01
Analyzed working principle and starting process of asynchronous motor direct torque control system. In order to solve the problem of serious fluctuation of starting current in traditional control scheme, the author puts forward a new kind of starting method which can limit voltage value to achieve the goal of reducing fluctuation of the current by increasing zero voltage vectors during the stage of starting. The author has also carried on simulation study on the system, and the result of simulation study shows that this method is effectual.
Pyrhoenen, O.
1998-12-31
Direct torque control (DTC) is a new control method for rotating field electrical machines. DTC controls directly the motor stator flux linkage with the stator voltage, and no stator current controllers are used. With the DTC method very good torque dynamics can be achieved. Until now, DTC has been applied to asynchronous motor drives. The purpose of this work is to analyse the applicability of DTC to electrically excited synchronous motor drives. Compared with asynchronous motor drives, electrically excited synchronous motor drives require an additional control for the rotor field current. The field current control is called excitation control in this study. The dependence of the static and dynamic performance of DTC synchronous motor drives on the excitation control has been analysed and a straightforward excitation control method has been developed and tested. In the field weakening range the stator flux linkage modulus must be reduced in order to keep the electro motive force of the synchronous motor smaller than the stator voltage and in order to maintain a sufficient voltage reserve. The dynamic performance of the DTC synchronous motor drive depends on the stator flux linkage modulus. Another important factor for the dynamic performance in the field weakening range is the excitation control. The field weakening analysis considers both dependencies. A modified excitation control method, which maximises the dynamic performance in the field weakening range, has been developed. In synchronous motor drives the load angle must be kept in a stabile working area in order to avoid loss of synchronism. The traditional vector control methods allow to adjust the load angle of the synchronous motor directly by the stator current control. In the DTC synchronous motor drive the load angle is not a directly controllable variable, but it is formed freely according to the motor`s electromagnetic state and load. The load angle can be limited indirectly by limiting the torque
Hassan Farhan Rashag
2013-04-01
Full Text Available Various aspects related to controlling induction motor are investigated. Direct torque control is an original high performance control strategy in the field of AC drive. In this proposed method, the control system is based on Space Vector Modulation (SVM, amplitude of voltage in direct- quadrature reference frame (d-q reference and angle of stator flux. Amplitude of stator voltage is controlled by PI torque and PI flux controller. The stator flux angle is adjusted by rotor angular frequency and slip angular frequency. Then, the reference torque and the estimated torque is applied to the input of PI torque controller and the control quadrature axis voltage is determined. The control d-axis voltage is determined from the flux calculator. These q and d axis voltage are converted into amplitude voltage. By applying polar to Cartesian on amplitude voltage and stator flux angle, direct voltage and quadratures voltage are generated. The reference stator voltages in d-q are calculated based on forcing the stator voltage error to zero at next sampling period. By applying inverse park transformation on d-q voltages, the stator voltages in &alpha and &beta frame are generated and apply to SVM. From the output of SVM, the motor control signal is generated and the speed of the induction motor regulated toward the rated speed. The simulation Results have demonstrated exceptional performance in steady and transient states and shows that decrease of torque and flux ripples is achieved in a complete speed range.
A. J. Arbi
2008-03-01
Full Text Available This paper presents a study of current sensor failure in a Direct Torque Control applied to a Double Fed Induction Generator based Variable Speed Wind System. The effect of scaling and offset current sensor errors is discussed through sensibility analysis. A control reconfiguration is then proposed to remedy this sensor failure. Simulation results emphasize the good performances of the proposed current sensor fault tolerant control
Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems
Preindl, Matthias; Schaltz, Erik
2011-01-01
to further improve dynamic behavior. It compensates the load torque influence on the speed control setting a feed forward torque reference value. The benefits are twice; the speed controller reaches the speed reference value without offsets which would need to be compensated by an integrator and a better...... response to load torque variations is obtained since they are detected and compensated leading to small speed variations. Moreover, the influence of parameter errors and disturbances has been analyzed and limited so that they play a minor role in operation....
Achalhi, A.; Bezza, M.; Belbounaguia, N.; Boujoudi, B.
2017-03-01
The performances of Direct Torque Control (DTC) of Induction machine are highly related to the inverter used therewith. The purpose of this paper is to highlight the efficiency of the space vector modulation (SVM) control of three level inverter associated with the direct torque control. The first part of this work is devoted to present the mathematical models of the DTC associated with 2-levels inverter then 3-levels inverter. Simulations on Matlab/Simulink will allow a comparative study to highlight advantages of the use of three levels inverter. The second part is devoted to the improvement of the DTC associated with a 3-levels inverter by application of the space vector modulation strategy (SVM) in order to manage the switching frequency and reduce harmonics. The efficiency of this solution will be attested by simulation on Matlab/Simulink.
Experimental Investigations on the Influence of Flux Control Loop in a Direct Torque Control Drive.
bhoopendra singh
2012-10-01
Full Text Available
Accurate flux estimation and control of stator flux by the flux control loop is the determining factor in effective implementation of DTC algorithm. In this paper a comparison of voltage model based flux estimation techniques for flux response improvement is carried out. The effectiveness of these methods is judged on the basis of Root Mean Square Flux Error (RMSFE and Total Harmonic Distortion (THD of stator current. The theoretical aspects of these methods are discussed and a comparative analysis is provided with emphasis on digital signal processor (DSP based controller implementation. Further the effect of operating flux on the performance of induction motor drive in terms of dynamic response, torque ripple and efficiency of operation is carried out. The proposed investigation is experimentally validated on a test drive.
Control of torque direction by spinal pathways at the cat ankle joint.
Nichols, T R; Lawrence, J H; Bonasera, S J
1993-01-01
To study the biomechanics of the calcaneal tendon's complex insertion onto the calcaneus, we measured torque-time trajectories exerted by the triceps surae and tibialis anterior muscles in eight unanesthetized decerebrate cats using a multi-axis force-moment sensor placed at the ankle joint. The ankle was constrained to an angle of 110 degrees plantarflexion. Muscles were activated using crossed-extension (XER), flexion (FWR), and caudal cutaneous sural nerve (SNR) reflexes. Torque contributions of other muscles activated by these reflexes were eliminated by denervation or tenotomy. In two animals, miniature pressure transducers were implanted among tendon fibers from the lateral gastrocnemius (LG) muscle that insert straight into the calcaneus or among tendon fibers from the medial gastrocnemius (MG) that cross over and insert on the lateral aspect of calcaneus. Reflexively evoked torques had the following directions: FWR, dorsiflexion and adduction; SNR, plantarflexion and abduction; and XER, plantarflexion and modest abduction or adduction. The proportion of abduction torque to plantarflexion torque was always greater for SNR than XER; this difference was about 50% of the magnitude of abduction torque generated by tetanic stimulation of the peronei. During SNR, pressures were higher in regions of the calcaneal tendon originating from MG than regions originating from LG. Similarly, pressures within the MG portion of the calcaneal tendon were higher during SNR than during XER, although these two reflexes produced matched ankle plantarflexion forces. Selective tenotomies and electromyographic recordings further demonstrated that MG generated most of the torque in response to SNR, while soleus, LG, and MG all generated torques in response to XER.(ABSTRACT TRUNCATED AT 250 WORDS)
CHEN Yong-jun; HUANG Sheng-hua; WAN Shan-ming; WU Fang
2008-01-01
A high-performance digital servo system built on the platform of a field programmable gate array (FPGA), a fully digitized hardware design scheme of a direct torque control (DTC) and a low speed permanent magnet synchronous motor (PMSM) is proposed. The DTC strategy of PMSM is described with Verilog hardware description language and is employed on-chip FPGA in accordance with the electronic design automation design methodology. Due to large torque ripples in low speed PMSM, the hysteresis controller in a conventional PMSM DTC was replaced by a fuzzy controller. This FPGA scheme integrates the direct torque controller strategy, the time speed measurement algorithm, the fuzzy regulating technique and the space vector pulse width modulation principle. Experimental results indicate the fuzzy controller can provide a controllable speed at 20 r min-1 and torque at 330 N m with satisfactory dynamic and static performance. Furthermore, the results show that this new control strategy decreases the torque ripple drastically and enhances control performance.
Weiran Wang
2013-06-01
Full Text Available In order to improve the performance of bearingless brushless DC motor, a closed-loop suspended force controller combining the discrete space voltage vector modulation is applied and the direct torque control is presented in this paper. Firstly, we increase the number of the control vector to reduce the torque ripple. Then, the suspending equation is constructed which is spired by the direct torque control algorithm. As a result, the closed-loop suspended force controller is built. The simulated and experimental results evaluate the performance of the proposed method. The more advantage is that the proposed algorithm can achieve the fast torque response, reduce the torque ripple, and follow ideal stator flux track. Furthermore, the motor which implants the closed-loop suspended force controller cannot onlyobtain the dynamic response rapidly and displacement control accurately, but also has the characteristics of bearingless brushless DC motor (such as simple structure, high energy efficiency, small volume and low failure rate.
Mustapha MESSAOUDI
2008-06-01
Full Text Available In this paper, the classical Direct Torque Control (DTC of Induction Motor (IM using an open loop pure integration suffers from the well-known problems of integration especially in the low speed operation range is detailed. To tackle this problem, the IM variables and parameters estimation is performed using a recursive non-linear observer known as EKF. This observer is used to estimate the stator currents, the rotor flux linkages, the rotor speed and the stator resistance. The main drawback of the EKF in this case is that the load dynamics has to be known which is not usually possible. Therefore, a new method based on the Model Reference Adaptive System (MRAS is used to estimate the rotor speed. The two different nonlinear observers applied to sensorless DTC of IM, are discussed and compared to each other. The rotor speed estimation in DTC technique is affected by parameter variations especially the stator resistance due to temperature particularly at low speeds. Therefore, it is necessary to compensate this parameter variation in sensorless induction motor drives using an online adaptation of the control algorithm by the estimated stator resistance. A simulation work leads to the selected results to support the study findings.
Chaoying Xia
2016-11-01
Full Text Available Compared to the doubly fed machine, the brushless doubly fed machine (BDFM has high reliability and low maintenance requirements. First, by taking the negative conjugation of the control motor variables in rotor reference frame, a state-space model of BDFM is derived. It is then transformed into synchronous reference frame, called synchronous reference frame state-space model (SSSM. In this way, all the variables of the SSSM are DC under the static state. Second, on the basis of the analysis of static equations, the possible output torque limits are obtained. Third, the causes of losing control are analyzed by the flux and the torque derivatives. A new control strategy called synthetic vector direct torque control (SVDTC is proposed to solve the losing control problems of the conventional direct torque control (DTC. Finally, the correctness of the results of this paper is verified by calculation examples and simulation results, the losing control problems can be solved, and the theoretical output capacity limits can be reached using SVDTC.
孙鹏
2014-01-01
Direct torque control has been applied widely due to its simple arithmetic, fast transient response and robust stability to parameter changed. As for the conventional direct torque control system for asynchronous motors, there is the effect of voltage space vector on the magnitude of stator flux and flux angle, especially there are large ripples at low speed. Aiming at this issue and based on conventional DTC, a new control strategy is proposed in this paper, this strategy combines flux linkage section subdivision control with synthesizing vectors and can improve the torque response time by introducing Fussy control algorithm, thereby reducing torque ripples effectively. Simulation results show that the strategy can greatly reduce the torque ripples and has a better dynamic and steady performance.%直接转矩控制具有控制简单、动态响应迅速、对参数变化鲁棒性强的特点，因此得到了广泛的应用。在传统的异步电动机直接转矩控制系统中，存在电压空间矢量对定子磁链幅值和磁通角的影响，特别是低速时系统脉动大。针对此问题，文章提出了一种的新的控制方法，该方法将磁链区间细分控制与电压矢量合成结合在一起，并通过引入模糊控制算法进一步提高了转矩响应时间，且减小了转矩脉动。仿真结果表明，本控制方法可以大大减小转矩脉动，具有较好的动静态性能。
Harmonic reduction of Direct Torque Control of six-phase induction motor.
Taheri, A
2016-07-01
In this paper, a new switching method in Direct Torque Control (DTC) of a six-phase induction machine for reduction of current harmonics is introduced. Selecting a suitable vector in each sampling period is an ordinal method in the ST-DTC drive of a six-phase induction machine. The six-phase induction machine has 64 voltage vectors and divided further into four groups. In the proposed DTC method, the suitable voltage vectors are selected from two vector groups. By a suitable selection of two vectors in each sampling period, the harmonic amplitude is decreased more, in and various comparison to that of the ST-DTC drive. The harmonics loss is greater reduced, while the electromechanical energy is decreased with switching loss showing a little increase. Spectrum analysis of the phase current in the standard and new switching table DTC of the six-phase induction machine and determination for the amplitude of each harmonics is proposed in this paper. The proposed method has a less sampling time in comparison to the ordinary method. The Harmonic analyses of the current in the low and high speed shows the performance of the presented method. The simplicity of the proposed method and its implementation without any extra hardware is other advantages of the proposed method. The simulation and experimental results show the preference of the proposed method.
Displaceable Gear Torque Controlled Driver
Cook, Joseph S., Jr. (Inventor)
1997-01-01
Methods and apparatus are provided for a torque driver including a displaceable gear to limit torque transfer to a fastener at a precisely controlled torque limit. A biasing assembly biases a first gear into engagement with a second gear for torque transfer between the first and second gear. The biasing assembly includes a pressurized cylinder controlled at a constant pressure that corresponds to a torque limit. A calibrated gage and valve is used to set the desired torque limit. One or more coiled output linkages connect the first gear with the fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. The torque limit is adjustable and may be different for fasteners within the same fastener configuration.
Chikhi Abdesselam
2010-01-01
Full Text Available This paper presents a comparative study of field-oriented control (IFOC and direct-torque control (DTC of induction motors using an adaptive flux observer. The main characteristics of field-oriented control and direct torque control schemes are studied by simulation, emphasizing their advantages and disadvantages. The performances of the two control schemes are evaluated in terms of torque, current ripples and transient responses to load toque variations. We can nevertheless observe a slight advance of DTC scheme compared to FOC scheme regarding the dynamic flux control performance and the implementation complexity. Consequently, the choice of one or the other scheme will depend mainly on specific requirements of the application.
F. Naceri
2010-01-01
Full Text Available This paper presents a new sensorless direct torque control method for voltage inverter – fed PMSM. The control methodis used a modified Direct Torque Control scheme with constant inverter switching frequency using Space Vector Modulation(DTC-SVM. The variation of stator and rotor resistance due to changes in temperature or frequency deteriorates theperformance of DTC-SVM controller by introducing errors in the estimated flux linkage and the electromagnetic torque.As a result, this approach will not be suitable for high power drives such as those used in tractions, as they require goodtorque control performance at considerably lower frequency. A novel stator resistance estimator is proposed. The estimationmethod is implemented using the Extended Kalman Filter. Finally extensive simulation results are presented to validate theproposed technique. The system is tested at different speeds and a very satisfactory performance has been achieved.
Blaabjerg, Frede; Andreescu, G.-D.; Pitic, C.I.;
2008-01-01
This paper proposes a motion-sensorless control system using direct torque control with space vector modulation for interior permanent magnet synchronous motor (IPMSM) drives, for wide speed range operation, including standstill. A novel stator flux observer with variable structure uses a combined...... voltage-current model with PI compensator for low-speed operations. As speed increases, the observer switches gradually to a PI compensated closed-loop voltage model, which is solely used at high speeds. High-frequency rotating-voltage injection with a single D-module bandpass vector filter and a phase...
基于空间矢量调制的直接转矩控制%Direct torque control based on space vector modulation
景晓东; 高赟; 李燕涛; 王坤
2013-01-01
针对传统的直接转矩控制存在较大的转矩和磁链脉动问题,提出了一种基于空间矢量调制的直接转矩控制策略.该控制策略采用磁链、转矩PI控制器代替传统直接转矩控制系统中的滞环比较器,以空间矢量脉宽调制代替电压矢量开关表合成电压矢量,来补偿磁链误差和转矩误差,达到消除滞环脉动的目的.Matlab/Simulink仿真结果表明,基于空间矢量调制的电动机控制系统相对于传统的直接转矩控制系统,磁链轨迹更接近圆形,转矩、磁链和电流响应脉动更小.%In view of problems of big ripple of torque and flux linkage of traditional direct torque control,the paper proposed a control strategy of direct torque control based on space vector modulation.The control strategy uses flux and torque PI controller to instead of hysteresis comparator of traditional direct torque control system,and adopts space vector pulse width modulation to instead of voltage vector switch to synthetic voltage vector which can compensate for flux error and torque error to avoid hysteresis ripple.The Matlab/Simulink simulation result shows that the flux truck of control system of motor based on space vector pulse width modulation is more closed to round,and its torque and flux and current ripple is smaller compared with the traditional direct torque control system.
Sayyed Asghar Gholamian
2013-07-01
Full Text Available Multiphase machines have gained an increasing attention due to their more advantages in comparison with three-phase machines. In recent literatures, only voltage source inverters (VSIs have been used to supply five-phase drives. Matrix converters (MCs pose many advantages over conventional VSIs, such as lack of dc-bulk capacitors, high quality power output waveform and higher number of output voltages. Due to some special applications of multiphase machines such as ship propulsion and aerospace, the volume of these drives is an important challenging problem. As a consequence, using MCs can be a reasonable alternative. In this paper, a new direct torque control (DTC algorithm using a three-to-five phase MC is proposed for five-phase permanent magnet synchronous motors (PMSMs. All of output voltage space vectors of three-to-five phase MC are extracted and a new switching table is proposed. Because of higher number of output voltages in MCs, there is a degree of freedom to control input power factor to keep close to unit moreover the torque and flux control. In other words, this proposed method use the advantages of both DTC method and MCs. Simulation results show the effectiveness of presented method in different operation modes.
Badrinarayan Bansilal Pimple
2015-02-01
Full Text Available This study proposes a polar voltage control-based direct torque control method to reduce the effects of unbalanced grid voltage on doubly-fed induction generator (DFIG-based wind turbine system. Under unbalanced grid voltage, the stator flux has a negative sequence component which leads to second harmonic pulsation in torque, stator active power, stator reactive power, stator current and rotor current. In the control scheme, the negative sequence rotor voltage vector is controlled to compensate the negative sequence stator flux by negative sequence rotor flux. Simulation study is carried out on a 2 MW DFIG system using MATLAB/SIMULINK. Feasibility of the proposed control strategy is experimentally verified on a 1.5 kW DFIG system.
贺德华; 刘国荣; 韦婷华; 徐美清; 曹时德; 周桂珍
2011-01-01
在传统的异步电动机直接转矩控制系统中,存在电压空间矢量对定子磁链幅值和磁通角的影响,特别是低速时系统脉动大.针对该问题,提出了一种的新的控制方法,将磁链区间细分控制与电压矢量合成相结合,并且为进一步提高转矩响应和减小转矩脉动,引入了模糊控制.仿真结果表明该控制方法可以大大减小转矩脉动,具有较好的动静态性能.%Considering the influence of voltage space vector on the magnitude of stator flux and the flux angle in the conventional direct torque control for induction motors especially large ripples at low speed, a new control strategy was presented in this paper. This strategy combined flux linkage section subdivide control with synthesizing vectors which can reduce torque ripples effectively. Fuzzy control was also introduced to improve torque response and decrease torque ripples. Simulation results show that a great reduction of torque ripples is achieved and the strategy has a better dynamic and steady performance.
孙笑辉; 韩曾晋
2001-01-01
Due to the large torque ripple of inductance motor based on direct torque control，especially in alow speed，this paper proposes a new control strategy．On the basis of conventional direct torque control，atorque ripple minimum controller is introduced in the strategy in order to decrease torque ripple．The simulationshows that it can get good torque performance．%针对基于直接转矩控制的感应电动机在低速运转时存在较大的转矩脉动问题，提出一种新的控制方法。该方法是在利用传统直接转矩控制原理的基础上，引入一个转矩脉动最小化控制器，以减小感应电动机的转矩脉动。仿真试验说明了该方法能够很好解决转矩脉动问题。
A Two-stage Kalman Filter for Sensorless Direct Torque Controlled PM Synchronous Motor Drive
Boyu Yi
2013-01-01
Full Text Available This paper presents an optimal two-stage extended Kalman filter (OTSEKF for closed-loop flux, torque, and speed estimation of a permanent magnet synchronous motor (PMSM to achieve sensorless DTC-SVPWM operation of drive system. The novel observer is obtained by using the same transformation as in a linear Kalman observer, which is proposed by C.-S. Hsieh and F.-C. Chen in 1999. The OTSEKF is an effective implementation of the extended Kalman filter (EKF and provides a recursive optimum state estimation for PMSMs using terminal signals that may be polluted by noise. Compared to a conventional EKF, the OTSEKF reduces the number of arithmetic operations. Simulation and experimental results verify the effectiveness of the proposed OTSEKF observer for DTC of PMSMs.
High Torque, Direct Drive Electric Motor Project
National Aeronautics and Space Administration — Bear Engineering proposes to advance the development of an innovative high torque, low speed, direct drive motor in order to meet NASA's requirements for such...
High Torque, Direct Drive Electric Motor Project
National Aeronautics and Space Administration — Bear Engineering proposes to develop an innovative high torque, low speed, direct drive motor in order to meet NASA's requirements for such devices. Fundamentally,...
Farina, Francesco; Bojoi, Radu; Tenconi, Alberto; Profumo, Francesco
A Direct Torque Control (DTC) strategy for dual-three phase induction motor drives is discussed in this paper. The induction machine has two sets of stator three-phase windings spatially shifted by 30 electrical degrees with isolated neutral points. The proposed control strategy is based on Proportional Integral (PI) regulators implemented in the stator flux synchronous reference frame. To improve the flux estimation, an Adaptive Stator Flux Observer (ASFO) has been used. Doing so, besides a better flux estimation in contrast to open-loop flux estimators, it is possible to use the observed currents to compensate the inverter non-linear behavior (such as dead-time effects), improving the drive performance at low speed. This is particularly important for low voltage/high current applications, as the drive considered in this paper. The advantages of the discussed control strategy are: constant inverter switching frequency, good transient and steady-state performance and less distorted machine currents in contrast to DTC schemes with variable switching frequency. Experimental results are presented for a 10kW dual three-phase induction motor drive prototype.
Ramesh, Tejavathu; Panda, A. K.; Kumar, S. Shiva
2013-08-01
In this research study, the performance of direct torque and flux control induction motor drive (IMD) is presented using five different speed control techniques. The performance of IMD mainly depends on the design of speed controller. The PI speed controller requires precise mathematical model, continuous and appropriate gain values. Therefore, adaptive control based speed controller is desirable to achieve high-performance drive. The sliding-mode speed controller (SMSC) is developed to achieve continuous control of motor speed and torque. Furthermore, the type-1 fuzzy logic speed controller (T1FLSC), type-1 fuzzy SMSC and a new type-2 fuzzy logic speed controller are designed to obtain high performance, dynamic tracking behaviour, speed accuracy and also robustness to parameter variations. The performance of each control technique has been tested for its robustness to parameter uncertainties and load disturbances. The detailed comparison of different control schemes are carried out in a MATALB/Simulink environment at different speed operating conditions, such as, forward and reversal motoring under no-load, load and sudden change in speed.
Direct Torque Control and Simulation of Permanent Magnet Synchronous Motor%永磁同步电机直接转矩控制及仿真
冯涛; 陆华
2013-01-01
A simple and effective direct torque control method based on permanent magnet synchronous motor was described.The direct torque control system was built by using simulink,and the performance of permanent magnet synchronous motor under different speeds and torque was analyzed.The feasibility of the method was verified through simulation analysis.This control method could satisfy the rapidity requirement,that was,it had good speed control characteristic.The results showed that stator flux and motor torque could be controlled effectively if a reasonable voltage space vector is selected.%介绍了一种基于永磁同步电机(PMSM)的简单有效的直接转矩控制(DTC)技术.利用Simulink搭建DTC系统,仿真分析了PMSM在不同转速和转矩条件下的性能,并验证算法的可行性.该控制技术能够满足系统控制快速性的要求,具有良好的速度控制特性.结果分析表明,定子磁链和电机转矩可通过选择合理的电压空间矢量得到有效控制.
Direct torque control of permanent magnet synchronous machines using Matrix Converters
Ortega García, Carlos
2008-01-01
La demanda d’aplicacions industrials avançades, fa que el control de màquines elèctriques de corrent altern (AC) sigui una disciplina contínuament creixent per satisfer l’alt nivell d’exigència. Tradicionalment, la màquina d’inducció (IM) ha estat la més utilitzada en aplicacions industrials de velocitat variable, incloent-ne bombes i ventiladors, màquines tèxtils i de paper, vehicles elèctrics, generació eòlica, etc. A més dels requeriments funcionals, l’estalvi energètic és, actualment, un ...
Decoupled Speed and Torque Control of IPMSM Drives Using a Novel Load Torque Estimator
ZAKY, M.
2017-08-01
Full Text Available This paper proposes decoupled speed and torque control of interior permanent magnet synchronous motor (IPMSM drives using a novel load torque estimator (LTE. The proposed LTE is applied for computing a load torque and yielding a feed-forward value in the speed controller to separate the torque control from the speed control. Indirect flux weakening using direct current component is obtained for high speed operation of the IPMSM drive, and its value for maximum torque per ampere (MTPA control in constant torque region is also used. LTE uses values of direct and quadrature currents to improve the behavior of the speed controller under the reference tracking and torque disturbances. The complete IPMSM drive by Matlab/Simulink is built. The effectiveness of the proposed control scheme using an experimental setup of the complete drive system implemented on a DSP-DS1102 control board is confirmed. Extensive results over a wide speed range are verified. The efficacy of the proposed method is confirmed in comparison to a conventional PI controller under both the reference speed tracking and load torque disturbance.
Ramesh, Tejavathu; Kumar Panda, Anup; Shiva Kumar, S
2015-07-01
In this research study, a model reference adaptive system (MRAS) speed estimator for speed sensorless direct torque and flux control (DTFC) of an induction motor drive (IMD) using two adaptation mechanism schemes are proposed to replace the conventional proportional integral controller (PIC). The first adaptation mechanism scheme is based on Type-1 fuzzy logic controller (T1FLC), which is used to achieve high performance sensorless drive in both transient as well as steady state conditions. However, the Type-1 fuzzy sets are certain and unable to work effectively when higher degree of uncertainties presents in the system which can be caused by sudden change in speed or different load disturbances, process noise etc. Therefore, a new Type-2 fuzzy logic controller (T2FLC) based adaptation mechanism scheme is proposed to better handle the higher degree of uncertainties and improves the performance and also robust to various load torque and sudden change in speed conditions, respectively. The detailed performances of various adaptation mechanism schemes are carried out in a MATLAB/Simulink environment with a speed sensor and speed sensorless modes of operation when an IMD is operating under different operating conditions, such as, no-load, load and sudden change in speed, respectively. To validate the different control approaches, the system also implemented on real-time system and adequate results are reported for its validation.
Direct Torque and Fault Tolerant Control for Six-phase Induction Motor%六相感应电机直接转矩及容错控制
耿乙文; 鲍宇; 王昊; 马鸿宇
2016-01-01
The problem of large torque ripples exists in conventional direct torque control (DTC). Based on the consideration of the six-phase induction motor with its own characteristics and analysis of the mathematical model, the paper proposed a six-phase induction motor direct torque control method. Firstly, the mathematical model of motors with normal and stator winding open-circuited conditions was built and analyzed respectively. Furthermore, formulation of a space vector pulse width modulation (SVPWM) provides a method to reduce stator current harmonics of the motor. Analysis of torque and flux provides a theoretical basis for the direct torque control. Finally, using the fuzzy reasoning and changing the duty ratio of the vector action time method, the inverter can output any angle and amplitude of the voltage vector. Experimental results show that the proposed strategy is able to reduce torque ripples and can improve current waveforms, and the torque dynamic response of the system is fast.%针对传统直接转矩控制转矩脉动大的问题，在考虑六相感应电机自身特点及分析其缺相数学模型的基础上，提出了一种六相感应电机直接转矩及容错控制方法。首先，建立和分析电机正常及缺相时的数学模型，并确定空间矢量脉宽调制(space vector pulse width modulation，SVPWM)方案以减小电机定子电流谐波含量；然后，通过对电机转矩和磁链进行分析，为直接转矩控制提供理论依据；在此基础上，利用模糊推理和改变矢量作用时间占空比的方法，使得逆变器可以输出任意角度和幅值的电压矢量。实验结果表明，该控制方案下电机转矩响应迅速，并能很好地改善电机转矩脉动和定子电流波形。
Direct Torque Control for Induction Motor Based on Space Vector Modulation%异步电动机的SVM-DTC控制
蒋建虎; 姬宣德
2011-01-01
针对基本直接转矩控制(BASIC-DTC)转矩和磁链脉动大的缺点,采用空间电压矢量调制与直接转矩控制相结合(SVM-DTC)的方法,以减小转矩和磁链脉动；为了提高定子磁链的观测精度,利用全阶磁链观测器观测定子磁链,并提出一种单自由度极点配置方法实现磁链观测器的极点配置.仿真结果表明,系统不但实现了转矩和磁链的定量控制,降低了转矩脉动和磁链脉动,提高了定子磁链的观测精度,而且同时使得逆变器开关周期恒定,更易于数字化实现.%For the disadvantage of the basic direct torque control (BASIC-DTC) 's torque and flux ripple when it runs, the direct torque control combined with space vector modulation (SVM-DTC) was used to reduce the torque and flux ripple. To improve the accuracy of the stator flux observation,the full order flux observer was used to achieve the stator flux observation. The new method of pole placement was proposed to achieve the configuration of the flux full order observer gain matrix parameters. The simulation results show that the torque ripple and flux ripple is reduced and the accuracy of the stator flux observation is improved,and in this method the invertor has constant switching period and is easy to realizing digital.
Peresada, Sergei; Kovbasa, Serhii; Dymko, Serhii; BOZHKO, Serhiy
2016-01-01
The paper presents a novel maximum torque per Ampere (MTA) controller for induction motor (IM) drives. The proposed controller exploits the concept of direct (observer based) field orientation and guarantees asymptotic torque tracking of smooth reference trajectories and maximizes the torque per Ampere ratio when the developed torque is constant or slowly varying. A dynamic output-feedback linearizing technique is employed for the torque subsystem design. In order to improve torque tracking a...
孙振川
2011-01-01
In order to solve the problems of the torque ripple and variable switching frequency in traditional direct torque control ( DTC) of the asynchronous machines, a new method based on duty ratio control was proposed in this paper. In duty ratio control technique, a zero voltage vector was applied in each sampling period to reduce the torque ripple. A new method of calculating the slopes of the rose and decline of the torque was proposed in this paper, the duty ratio can be calculated. Finally, the proposed strategy was verified by simulations. Simulation results show that a great reduction of torque ripple was achieved. The switch frequency of the inverter can be made constant by setting the fixed sampling period. Therefore, a good statistic and dynamic performance are obtained.%为了解决直接转矩控制中转矩脉动过大、开关频率不固定等问题,文中提出了一种新的基于占空比控制的异步电动机直接转矩控制方案.占空比控制技术通过在每个采样周期中插入零电压矢量来减小转矩的波动.本文提出了一种新的计算转矩上升和下降斜率的方法,求解出了占空比的计算公式.最后,对所提出的直接转矩控制算法进行了仿真.仿真结果表明,该方案可以大大减小输出转矩的波动.通过设定固定的采样周期,可以使逆变器的开关频率保持恒定,从而大大改善了调速系统的静、动态性能.
无轴承无刷直流电机的直接转矩控制%Direct torque control of bearingless brushless DC motor
许洁; 刘贤兴; 李兵伟
2012-01-01
无轴承无刷直流电机结合了无轴承电机和无刷直流电机的优点、具有良好的行特性和广泛的运用前景.研究了无轴承无刷直流电机的控制方法,并将直接转矩控制技术应用于无轴承无刷直流电机的转矩绕组.通过Matlab/Simulink仿真和实验结果表明,转矩绕组的直接转矩控制(DTC)能提高系统的响应速度,减少转矩脉动,提高系统的静动态性能且控制方法简单有效.%Bearingless brushless DC motor, combining advantages of brushless DC motor and bearingless motor, has favorable operating characteristics and wide range of applications. In this paper, the control method of bear ingless brushless DC motor is researched, and the bearingless brushless DC motor's torque winding is controlled by using the method of direct torque control ( DTC ). By Matlab/Simulink simulation and experiment of the con trol system, the results show that the application of DTC to torque winding control of bearingless brushless DC motor is correct and feasible. DTC improves the system's response speed, reduces torque ripple, and optimizes the control effect. The control method is relatively simple.
无刷直流电机无位置传感器直接转矩控制%Direct Torque Control of Sensorless Brushless DC Motor
雷雄
2012-01-01
A direct torque control for sensorless brushless DC motor is presented in this paper. The control method presented requires observation of the DC bus voltage and the three-phase stator currents of brushless DC motor, and estimate the flux, torque, and rotor position angles of motor In order to control brushless DC motor, the appropriate voltage space vector is selected according to the torque, current component on d-q axes and rotor position. The simulation and experimental results show that the control method is valid and feasible.%本文提出了一种将直接转矩控制应用于无刷直流电机的无位置传感器控制方法。需观测无刷直流电机的直流母线电压及定子侧的三相电流，从而估算出电机的磁链、转矩以及位置角，再根据转矩、d-q坐标系上的电流分量以及转子位置信息来选择相应的电压空间矢量，以实现对无刷直流电机的控制。仿真和实验结果表明本文提出的控制方法有效可行。
Torque Control of Friction Stir Welding Project
National Aeronautics and Space Administration — Longhurst Engineering, PLC and Vanderbilt University propose the innovation of torque control of friction stir welding (FSW) as a replacement to force control of...
Fuzzy Direct Torque Control System Simulation by Matlab/simulink%模糊直接转矩控制系统MATLAB/SIMULINK仿真
窦曰轩; 王洪艳
2001-01-01
文章采用MATLAB5.2/SIMULINK建立模糊直接转矩控制系统的仿真模型，介绍了用SIMULINK软件进行封装、S函数设计及用模糊工具箱设计模糊控制器的方法，并通过仿真结果验证了此模型的正确性。%This paper uses MATLAB5.2/SIMULINK to build fuzzy direct torque control system's simulating model.SIMULINK software is used for masking and designing S-function,we also design fuzzy controller by using Fuzzy Toolbox.Simulating result is presented to demonstrate this model is true.
A Comparative Performance Analysis of Torque Control Schemes for Induction Motor Drives
R Rajendran
2012-03-01
Full Text Available This paper presents a comparative study of field-oriented control(FOC, conventional direct torque control(DTC and proposed space vector modulated direct torque control with low pass filter(SVM-DTC. The main characteristics of FOC, DTC and proposed SVM-DTC schemes are studied by simulation, emphasizing their advantages and disadvantages. The performance of three control schemes is evaluated in terms of torque, current ripples and transient responses. It is shown that the proposed scheme improves the performance by combining a low torque, current ripple characteristics with fast torque dynamics.
Implementing Torque Control with High-Ratio Gear Boxes and without Joint-Torque Sensors
Del Prete, Andrea; Mansard, Nicolas; Ramos Ponce, Oscar Efrain; Stasse, Olivier; Nori, Francesco
2016-01-01
International audience; This paper presents a complete framework (estimation, identification and control) for the implementation of joint-torque control on the humanoid robot HRP-2. While torque control has already been implemented on a few humanoid robots, this is one of the first implementations of torque control on a robot that was originally built to be position controlled (iCub[1] and Asimo[2] being the first two, to the best of our knowledge). The challenge comes from both the hardware,...
基于GA+BP网络速度辨识的直接转矩控制%Speed Observe of Direct Torque Control Based on GA and BP Network
蔡斌军
2012-01-01
There are big ripples in motor drive on current and flux linkage and. torque when using traditional direct torque control (DTC) . System with speed sensor has lower reliability and higher system cost. To solve these problems, a strategy has been put forward that using Genetic algorithm ( GA) optimize BP neural network motor speed identifier, thus speed sensor-less direct torque control for induction motor is realized. Rapid torque response and strong robustness of direct torque control method are still maintained. Ripples on current and flux linkage and torque axe dramatically reduced. In the mean time, the system based on BP and GA is robust to motor load disturbance. The system dynamic and static performance are dramatically improved. The experimental results show the feasibility and effectiveness of this method.%针对传统直接转矩控制中存在电流、磁链和转矩脉动较大及速度传感器的使用降低了系统的可靠性,增加了系统的成本等问题,提出了利用遗传算法(GA)优化的BP网络电机速度辨识方法,实现了异步电机无速度传感器直接转矩控制.该方法保持了直接转矩控制固有的转矩响应快和系统鲁棒性强的优点,降低了磁链、转矩脉动,加快了系统的响应速度,并对负载的扰动具有较强的鲁棒性,有效地改善了系统的动、静态性能,实验结果证实了该方法的可行性和有效性.
Torque Control of Electrorheological Fluidic Actuators
Vitrani, Marie-Aude; Nikitczuk, Jason; Morel, Guillaume; Mavroidis, Constantinos
2004-01-01
International audience; In this paper, the experimental closed loop torque control of electro-rheological fluids (ERF) based actuators for haptic applications is performed. ERFs are liquids that respond mechanically to electric fields by changing their properties, such as viscosity and shear stress, electroactively. Using the electrically controlled rheological properties of ERFs, we developed actuators for haptic devices that can resist human operator forces in a controlled and tunable fashi...
某种永磁同步发电机直接转矩控制系统设计%A Permanent Magnet Synchronous Generator Direct Torque Control System Design
张进超; 王玲; 郝永平; 张令涛
2015-01-01
Based on two dimensional trajecto-ry correction principle, a revised steering gear method of direct torque control of permanent mag-net synchronous generator is proposed.For a per-manent magnet synchronous motor model of d q coordinates,a permanent magnet synchronous mo-tor direct torque control scheme is studied.The re-sults showed that corrected steering gear direct torque control system of the generator output torque can achieve high speed rotating projectile correction.%依据二维弹道修正原理，提出修正舵机中永磁同步发电机直接转矩控制方法，针对 d q 坐标系下的永磁同步电机模型，研究了永磁同步电机直接转矩控制方案。结果表明，修正舵机中发电机直接转矩控制系统输出转矩能够达到高速旋转弹的修正效果。
杨俊华; 刘远涛; 谢景凤; 刘慧媛; 吴捷
2011-01-01
A novel sliding-mode variable structure（SMVS） control strategy is proposed to reduce the ripples of ？ux and torque of brushless double-fed machines（BDFM） based on direct torque control system（DTC）.In order to ensure the constant switching frequency for the inverter,two hysteresis regulators in the conventional DTC system are substituted by the SMVS controllers of ？ux and torque,and the space voltage vector pulse-width-modulation is used in the output of the voltage vector switches.The SMVS controllers are designed with the method of exponential approach law,and the Lyapunov stability theory is utilized to solve for the control law of the SMVS controllers.The simulation model of DTC is established in MATLAB/Simulink environment.The simulation results show that this new control method effectively reduces the torque ripples and improves the waveforms of the stator ？ux and current.The inherent advantage of the fast dynamic-response of the torque in DTC is reserved.The stability and robust performance of the system is enhanced.%针对无刷双馈电机直接转矩控制系统磁链和转矩脉动大的问题,引入滑模变结构控制策略.以转矩和磁链两个滑模控制器来代替传统直接转矩控制中的两个滞环控制器,电压矢量开关的输出采用空间电压矢量PWM调制的方法,保证了逆变器开关频率恒定,应用指数趋近率方法设计滑模控制器,由Lyapunov方法求得相应的滑模变结构控制律,建立了MATLAB/Simulink环境下直接转矩控制系统的仿真模型,仿真结果表明,新型控制方案能有效减小转矩脉动,改善定子磁链和电流波形,同时仍可保持直接转矩控制固有的转矩快速响应的优点,提高系统的稳定性和鲁棒性.
Converting a commercial electric direct-drive robot to operate from joint torque commands
Muir, P.F.
1991-07-01
Many robot control algorithms for high performance in-contact operations including hybrid force/position, stiffness control and impedance control approaches require the command the joint torques. However, most commercially available robots do not provide joint torque command capabilities. The joint command at the user level is typically position or velocity and at the control developer level is voltage, current, or pulse-width, and the torque generated is a nonlinear function of the command and joint position. To enable the application of high performance in-contact control algorithms to commercially available robots, and thereby facilitate technology transfer from the robot control research community to commercial applications, an methodology has been developed to linearize the torque characteristics of electric motor-amplifier combinations. A four degree of freedom Adept 2 robot, having pulse-width modulation amplifiers and both variable reluctance and brushless DC motors, is converted to operate from joint torque commands to demonstrate the methodology. The commercial robot controller is replaced by a VME-based system incorporating special purpose hardware and firmware programmed from experimental data. The performance improvement is experimentally measured and graphically displayed using three-dimensional plots of torque vs command vs position. The average percentage torque deviation over the command and position ranges is reduced from as much as 76% to below 5% for the direct-drive joints 1, 2 and 4 and is cut by one half in the remaining ball-screw driven joint 3. Further, the torque deviation of the direct-drive joints drops below 2.5% if only the upper 90% of the torque range is considered. 23 refs., 20 figs., 2 tabs.
A hybrid attitude controller consisting of electromagnetic torque rods and an active fluid ring
Nobari, Nona A.; Misra, Arun K.
2014-01-01
In this paper, a novel hybrid actuation system for satellite attitude stabilization is proposed along with its feasibility analysis. The system considered consists of two magnetic torque rods and one fluid ring to produce the control torque required in the direction in which magnetic torque rods cannot produce torque. A mathematical model of the system dynamics is derived first. Then a controller is developed to stabilize the attitude angles of a satellite equipped with the abovementioned set of actuators. The effect of failure of the fluid ring or a magnetic torque rod is examined as well. It is noted that the case of failure of the magnetic torque rod whose torque is along the pitch axis is the most critical, since the coupling between the roll or yaw motion and the pitch motion is quite weak. The simulation results show that the control system proposed is quite fault tolerant.
史涔溦; 邱建琪; 金孟加; Friedrich W.Fuchs
2005-01-01
提出一种用于永磁同步电动机的基于磁链误差矢量补偿的直接转矩控制(EFVC-DTC)策略,给出了磁链误差矢量的估计算法,并将该控制策略下的稳态和动态运行性能与常规DTC进行比较.仿真及实验结果表明EFVC-DTC可以使电力开关器件工作在基本固定的频率上,磁链和转矩脉动显著减小,比常规DTC具有更优越的稳态性能,而动态转矩响应几乎与常规DTC相同.%A modified direct torque control strategy based on error flux linkage vector compensation (EFVC-DTC) for permanent magnet synchronous machines (PMSM) is presented. The theoretical background of EFVC-DTC is introduced and an algorithm to estimate the flux linkage error is proposed. The steady state and dynamic performances of EFVC-DTC have been compared with those of the conventional direct torque control (DTC). The simulation and experimental results confirm that both flux linkage and torque ripples are significantly reduced in EFVC-DTC with a fixed switching frequency while the dynamic torque response isalmost as good as the basic DTC.
杨影; 陈鑫; 涂小卫; 韩冰
2014-01-01
Calculation duty ratio is an important issue in Direct torque control ( DTC) of permanent mag-net synchronous motor ( PMSM) based on the duty ratio modulation. The effect of zero vector on elctro-magnetic torque during all speed range was analyzed on the basis of the relation between voltage vector and torque current component and an important phenomenon was revealed and explained that torque rip-ple in low speed range is less than that in high speed range in DTC based on the duty ratio modulation. A robust DTC method of PMSM based on the duty ratio control was designed in which the duty ratio is cal-culated with the error of torque and flux. The method is simple to implement and insensitive to motor pa-rameter error. Simulation and experiments are carried out and show that the improved DTC based on duty ratio modulation has the advantage of simplicity, robustness and improved performance in low speed.%针对如何确定占空比调制的永磁同步电机直接转矩控制的零矢量作用时间问题。根据电压矢量与电流转矩分量关系，分析了在不同转速下零矢量作用时电磁转矩的变化规律，引入占空比调制后低速区转矩脉动要小于中高速区转矩脉动。设计了基于占空比调制的永磁同步电机直接转矩控制系统，利用转矩偏差和定子磁链的偏差计算占空比，该方案易于实现，对电机参数误差不敏感。仿真和实验结果表明，该方法结构简单、鲁棒性强，能够明显改善低速性能。
Heat Control via Torque Control in Friction Stir Welding
Venable, Richard; Colligan, Kevin; Knapp, Alan
2004-01-01
In a proposed advance in friction stir welding, the torque exerted on the workpiece by the friction stir pin would be measured and controlled in an effort to measure and control the total heat input to the workpiece. The total heat input to the workpiece is an important parameter of any welding process (fusion or friction stir welding). In fusion welding, measurement and control of heat input is a difficult problem. However, in friction stir welding, the basic principle of operation affords the potential of a straightforward solution: Neglecting thermal losses through the pin and the spindle that supports it, the rate of heat input to the workpiece is the product of the torque and the speed of rotation of the friction stir weld pin and, hence, of the spindle. Therefore, if one acquires and suitably processes data on torque and rotation and controls the torque, the rotation, or both, one should be able to control the heat input into the workpiece. In conventional practice in friction stir welding, one uses feedback control of the spindle motor to maintain a constant speed of rotation. According to the proposal, one would not maintain a constant speed of rotation: Instead, one would use feedback control to maintain a constant torque and would measure the speed of rotation while allowing it to vary. The torque exerted on the workpiece would be estimated as the product of (1) the torque-multiplication ratio of the spindle belt and/or gear drive, (2) the force measured by a load cell mechanically coupled to the spindle motor, and (3) the moment arm of the load cell. Hence, the output of the load cell would be used as a feedback signal for controlling the torque (see figure).
Aspects Concerning the Torque Ripple Control of the Brushless DC Motor
BALUTA, G.
2013-05-01
Full Text Available This paper deals with two advanced numerical structures to control the electromagnetic torque ripple of Brushless Direct Current Motors (BLDCM, indirectly achieved by phase currents control and directly by the Direct Torque Control (DTC technique. In DTC there was implemented an observer to increase the rudimentary transducer resolution, containing three Hall Effect sensors. The experimental results describe the evolution of torque in both situations of control and are obtained by applying a control strategy for an electric drive system with BLDCM with trapezoidal Back-EMF in Two-Phase Mode.
DTC Based Induction Motor Speed Control Using 10-Sector Methodology for Torque Ripple Reduction
Pavithra, S.; Dinesh Krishna, A. S.; Shridharan, S.
2014-09-01
A direct torque control (DTC) drive allows direct and independent control of flux linkage and electromagnetic torque by the selection of optimum inverter switching modes. It is a simple method of signal processing which gives excellent dynamic performance. Also transformation of coordinates and voltage decoupling are not required. However, the possible discrete inverter switching vectors cannot always generate exact stator voltage required, to obtain the demanded electromagnetic torque and flux linkages. This results in the production of ripples in the torque as well as flux waveforms. In the present paper a torque ripple reduction methodology is proposed. In this method the circular locus of flux phasor is divided into 10 sector as compared to six sector divisions in conventional DTC method. The basic DTC scheme and the 10-sector method are simulated and compared for their performance. An analysis is done with sector increment so that finally the torque ripple varies slightly as the sector is increased.
Paicu, M. C.; Boldea, I.; Andreescu, G. D.
2009-01-01
in the rotor position and speed estimation is obtained. For IPMSM, a stator-flux observer is employed based on combined current and voltage models, with speed-dependent smooth transition between them using a PI compensator of flux error. Comparative experimental results using both sensorless control systems...
吴伟乾; 凌有铸; 陈孟元
2016-01-01
为抑制传统直接转矩控制系统中固有的磁链和转矩脉动，分析了零矢量在永磁同步电机(PMSM)直接转矩控制中对磁链和转矩的影响。基于电压空间矢量调制技术当中电压矢量合成的控制思想，采取有效电压矢量和零矢量共同作用的控制方式构成基于占空比调制的 PMSM直接转矩控制系统(DTC－DRM)，并改进了占空比的计算方式，以转矩偏差、定子磁链偏差以及电机的转速信息来计算占空比，所需参数少，简化了传统占空比控制技术复杂的占空比计算。与传统DTC的仿真结果对比，验证了系统方案的可行性和有效性，且能保持系统结构简单和较强的鲁棒性。%To reduce the undesired torque and flux ripple in conventional direct torque control(DTC),this paper presents a novel direct torque control strategy based on duty ratio modulation (DTC-DRM) through the voltage synthesis theory in the space voltage vector modulation.The effect of zero vector on direct torque control is analyzed,and the combination of active vector and zero vector is also introduced. To distinguish from the conventional methods,the duty ratio is determined according to the torque error and flux error,and the speed of PMSM,which can simplify the calculation,with less parameters of PMSM needed.The results of simulation are compared between proposed strategy and conventional DTC,indicating that an obvious reduction of the flux and torque ripple is achieved,and the simplicity and robustness of DTC are maintained.
Controlling the spin-torque efficiency with ferroelectric barriers
Useinov, A.
2015-02-11
Nonequilibrium spin-dependent transport in magnetic tunnel junctions comprising a ferroelectric barrier is theoretically investigated. The exact solutions of the free electron Schrödinger equation for electron tunneling in the presence of interfacial screening are obtained by combining Bessel and Airy functions. We demonstrate that the spin transfer torque efficiency, and more generally the bias dependence of tunneling magneto- and electroresistance, can be controlled by switching the ferroelectric polarization of the barrier. In particular, the critical voltage at which the in-plane torque changes sign can be strongly enhanced or reduced depending on the direction of the ferroelectric polarization of the barrier. This effect provides a supplementary way to electrically control the current-driven dynamic states of the magnetization and related magnetic noise in spin transfer devices.
杨晓武; 李干蓉; 李劲松
2012-01-01
The advantage and application area of Brushless Direct Current Motor（BLDCM） was described, the relative mathematic model was built and the effect of electromagnetic torque ripple on the performance of BLDCM was elaborat- ed. The paper discussed factors that affected the torque ripple from the case of the ideal back-EMF and non-ideal back-EMF for BLDCM, then the relevant control strategy are put forward to minimize the torque ripple. The strategy com- bines the advanced commutation with the current control to minimize the torque ripple caused by non-ideal back-EMF. Finally, the paper built simulation model for BLDCM by using software MATLAB according to the proposed control strat- egy targeted at torque ripple, the experimental simulation results show that the proposed control strategy for reducing torque ripple is correct and reasonable.%在介绍无刷直流电机的优点及其应用领域的基础上，建立了电机的基本数学模型，并且阐述了其电磁转矩波动对电机运行中性能的影响，重点从理想反电动势无刷直流电机和非理想反电动势无刷直流电机两种情况下分析电磁转矩波动的因素，并采用相对的控制策略来控制电磁转矩波动；提前角开通换相法与电流控制相结合的控制策略，最后，利用MATLAB仿真软件组建了无刷直流电机的仿真模型，仿真实验结果验证了所提出的转矩波动控制策略的合理性和正确性。
Direct Torque Control of Induction Motor Based on Back-stepping Principle%基于反推原理感应电机直接转矩控制
刘艳科; 申群太
2012-01-01
In order to achieve high performance on induction motor control, to solve the parameter perturbations , uncertainties and other issues , the application of a nonlinear controller based on the principle of back-stepping was used, consider the induction motor iron loss in the static model to establish non-linear motor controller. The overall stability of the controller was proved by Lyapunov theory, using the voltage space vector modulation to direct torque control system. Simulation slows that using back-stepping controller enabled direct torque control of induction motors to achieve good tracking results.%为了实现感应电机高性能控制,克服运行过程参数摄动、不确定等问题的影响,应用反推原理设计的非线性控制器,考虑感应电机的铁损.并且通过李雅普诺夫理论证明控制器的整体稳定,采用电压空间矢量调制,应用于直接转矩控制系统.仿真结果表明,采用反推原理设计控制器能够使感应电机直接转矩控制达到很好的跟踪效果,具有推广意义.
高中臣; 张爱玲; 陈晨
2009-01-01
To reduce the low speed torque ripple of induction motor and keep constant switch frequency, this paper proposed a new control strategy on the basis of direct torque control (DTC),which uses Space Vector Pulse Width Modulation instead of switch table.The experiment and simulation results show that it can reduce the torque ripple,and improve the waveform of stator flux and current.%针对传统直接转矩控制开关频率不恒定及低速时的转矩脉动大的缺点,采用了基于SVPWM的直接转矩控制方法.根据转矩和定子磁链的误差确定应该施加的参考电压矢量,然后利用电压空间矢量脉宽调制(SVPWM)的方法合成该矢量.仿真和实验结果表明,基于SVPWM的直接转矩控制(SVPWM-DTC)能够有效减小转矩脉动,改善磁链和电流波形.
黄祯祥; 吴峻; 邓怀雄
2012-01-01
Based on active-disturbance rejection controller( ADRC ) theory, a direct torque control (DTC) system of permanent magnet AC servo was established. In the system uncertain external load disturbance( external disturbances) and system parameters variations (internal disturbances) were regarded as one integrated disturbance,and ADRC was used to observe and compensate this integrated disturbance. The simulation results show this system has very strong robustness not only to uncertain external load disturbance,but also to internal parameter variations such as coefficient of torque. Compared with PI controller,the system has higher dynamic performance,powerful capability of anti-interference and high control precision,etc.%设计了一种基于自抗扰控制器的永磁同步电动机直接转矩控制系统.该系统将不确定性负载扰动(外扰)和系统参数变化(内扰)视为一个综合扰动项,然后利用自抗扰控制器(ADRC)对综合扰动项进行观测和补偿.仿真结果证明,该系统不仅有效地抑制了不确定负载扰动的影响,同时对系统内部参数如电机转动惯量等摄动也具有较强的鲁棒性.该系统相比PI控制具有动态控制性能优越、抗扰能力强、控制精度高等特点.
The role of interaction torque and muscle torque in the control of downward squatting
Fujisawa, Hiroyuki; Suzuki, Hiroto; Murakami, Kenichi; Kawakami, Shingo; Suzuki, Makoto
2016-01-01
[Purpose] The purposes of this study were first to analyze the multijoint dynamics of downward squatting, and to examine the contribution of interaction torque and muscle torque to net torque, and second, to examine mechanisms of movement control. [Subjects] The subjects were 31 healthy men with a mean age of 21.0 ± 1.2 years (range, 19–24 years). [Methods] Squatting tasks with the trunk in two positions, an erect and anterior tilt position, were performed by the subjects. Net, interaction, m...
Vess, Melissa F.; Starin, Scott R.
2007-01-01
During design of the SDO Science and Inertial mode PID controllers, the decision was made to disable the integral torque whenever system stability was in question. Three different schemes were developed to determine when to disable or enable the integral torque, and a trade study was performed to determine which scheme to implement. The trade study compared complexity of the control logic, risk of not reenabling the integral gain in time to reject steady-state error, and the amount of integral torque space used. The first scheme calculated a simplified Routh criterion to determine when to disable the integral torque. The second scheme calculates the PD part of the torque and looked to see if that torque would cause actuator saturation. If so, only the PD torque is used. If not, the integral torque is added. Finally, the third scheme compares the attitude and rate errors to limits and disables the integral torque if either of the errors is greater than the limit. Based on the trade study results, the third scheme was selected. Once it was decided when to disable the integral torque, analysis was performed to determine how to disable the integral torque and whether or not to reset the integrator once the integral torque was reenabled. Three ways to disable the integral torque were investigated: zero the input into the integrator, which causes the integral part of the PID control torque to be held constant; zero the integral torque directly but allow the integrator to continue integrating; or zero the integral torque directly and reset the integrator on integral torque reactivation. The analysis looked at complexity of the control logic, slew time plus settling time between each calibration maneuver step, and ability to reject steady-state error. Based on the results of the analysis, the decision was made to zero the input into the integrator without resetting it. Throughout the analysis, a high fidelity simulation was used to test the various implementation methods.
The effect of knee joint angle on torque control.
Sosnoff, Jacob J; Voudrie, Stefani J; Ebersole, Kyle T
2010-01-01
The purpose of the author's investigation was to examine the effect of knee joint angle on torque control of the quadriceps muscle group. In all, 12 healthy adults produced maximal voluntary contractions and submaximal torque (15, 30, and 45% MVC [maximal voluntary contraction]) at leg flexion angles of 15 degrees , 30 degrees , 60 degrees , and 90 degrees below the horizontal plane. As expected, MVC values changed with respect to joint angle with maximum torque output being greatest at 60 degrees and least at 15 degrees . During the submaximal tasks, participants appropriately scaled their torque output to the required targets. Absolute variability (i.e., standard deviation) of torque output was greatest at 60 degrees and 90 degrees knee flexion. However, relative variability as indexed by coefficient of variation (CV) decreased as joint angle increased, with the greatest CV occurring at 15 degrees . These results are congruent with the hypothesis that joint angle influences the control of torque.
薛诚; 宋文胜; 冯晓云
2016-01-01
The multi-phase permanent magnet synchronous machine (PMSM) has the property of small size, low noise and high power density, so it has been widely used in high-power and low-voltage occasion. Based on the analysis of traditional direct torque control (DTC) models and space vector pulse width modulation (SVPWM) technologies, a fixed switching frequency modified DTC algorithm of five-phase PMSM with multi-objective optimization was proposed, which aims at improving the trajectory of stator flux effectively, reducing torque ripples and low harmonic components of stator currents. The proposed algorithm brings the following benefits: such as fast torque control dynamic response, the fixed switching frequency, the optimization control of torque, stator flux and stator phase currents. Simulation and experimental results show the feasibility and effectiveness of the proposed algorithm.%多相永磁同步电机驱动系统因具有体积小、噪声低、功率密度高等诸多优点，在低压、大功率输出及可靠性要求高的场合已得到了广泛关注和应用。该文以五相永磁同步电机为研究对象，分析并建立传统直接转矩控制(direct torque control，DTC)算法数学模型，在此基础上，以进一步优化转矩纹波及磁链轨迹，降低定子电流低次谐波为控制目标，结合空间矢量脉宽调制(space vector pulse width modulation， SVPWM)技术，提出改进DTC的定频多目标优化控制模型。该算法不仅保持了传统DTC快速的转矩控制动态响应，实现了开关频率恒定及转矩的无稳态误差，同时也兼顾了定子磁链以及相电流的优化控制。仿真和实验结果均表明该算法的正确性和有效性。
螺旋桨负载永磁同步电机直接转矩控制系统研究%Research on the direct torque control system of PMSM with propeller load
任俊杰; 刘彦呈; 赵友涛; 郭昊昊
2012-01-01
To research the performance of the variable frequency speed regulation system used the space vector modu-lation strategy for permanent magnet synchronous motor ( PMSM) with the propeller load, through combining the analysis of direct torque control ( DTC ) and propeller load characteristic theory with the open water curve of the propeller, it obtained the function relationship for thrust coefficient Kp and torque coefficient Km with the advance speed ratio /, respectively. It proposed the calculation method of thrust and torque coefficient and established the PMSM DTC simulation model with propeller load. The simulation results show that the response time of the motor dynamic speed is fast in DTC system, and the electromagnetic torque is equal to the load torque produced by rotating propeller when the motor speed in steady states. Compared with the measured motor's operation data, the simulation motor torque value is consistent with the measured data in different rotating speeds and verify the validity of the model.%为了研究空间矢量调制策略对大功率永磁同步电机在螺旋桨负载特性下变频调速性能的影响,通过对直接转矩控制变频调速和螺旋桨负载特性理论的分析,结合螺旋桨敞水特性曲线,得到螺旋桨推力系数Kp和扭矩系数Km分别与进速比J之间的函数关系.提出了推力系数和扭矩系数的计算方法,建立了螺旋桨负载和永磁推进电机直接转矩控制的仿真模型.仿真结果表明,直接转矩控制系统中永磁推进电机转速动态响应快,转速稳定后电磁转矩与螺旋桨旋转产生的负载转矩相等.与实测电机运行数据比较可知,不同转速下仿真得到的电机转矩值与实测值相一致,验证了该模型的有效性.
Super-twisting sliding mode direct torque contol of induction machine drives
Lascu, Cristian; Blaabjerg, Frede
2014-01-01
This paper presents a new super-twisting sliding modes direct torque and flux controller (STSM-DTC) for induction motor (IM) drives. The STSM is a second-order (type two) variable-structure control which operates without high-frequency chattering. The proposed STSM scheme is a torque and stator...... flux magnitude controller implemented in the stator flux reference frame, and it does not employ current controllers as in conventional vector control. This controller contains a design parameter that allows the designer to balance its operation between a linear PI-like behavior and a constant......-DTC control, design and implementation details, and relevant experimental results for a sensorless IM drive. The scheme is compared to a second-order sliding mode controller and a linear PI controller. A robustness assessment against the PI controller is also included....
陈修波; 黎健明; 张志林; 金挺; 杭俊
2014-01-01
结合EPS系统的功能特点，提出1种适用于汽车转向的无刷直流电机（ BLDC）系统直接转矩控制（ DTC）方法，以提升汽车转向系统的控制性能。从BLDC系统的转矩特性和磁链特性的关系入手，根据电机系统的转矩、磁链跟踪误差及定子磁链所处扇区号，查询预先规划的离线查找表（ LUT），直接输出最优的电压空间矢量。并基于Matlab/Simulink仿真平台进行BLDC调速系统的仿真实验。结果表明，DTC方法可以对电磁转矩脉动进行有效控制，而且能大大提高BLDC的动、稳态驱动性能，提供了1种适用于电动助力转向EPS系统控制的新思路。%According to the functional characteristics of EPS system , this article proposes a brushless DC motor ( BLDC) direct torque control ( DTC) method which is suitable to the automobile steering to improve the control performance of the automobile steering system .Beginning with the relationship between the torque and flux linkage characteristics of BLDC system , and according to the motor system′s torque, flux tracking error and sector number of the stator , it is to search for the pre-planned offline lookup table ( LUT) and directly output the optimal voltage space vector .Finally, the experiment of BLDC control system is simulated based on the Matlab/Simulink simulation platform .The experimental results show that the DTC method can effectively control the electromagnetic torque ripple , and greatly improve the dynamic , steady driving performance of BLDC , and provide a new idea that is suitable for the EPS control of the electric power steering system .
Super-twisting sliding mode direct torque contol of induction machine drives
Lascu, Cristian; Blaabjerg, Frede
2014-01-01
This paper presents a new super-twisting sliding modes direct torque and flux controller (STSM-DTC) for induction motor (IM) drives. The STSM is a second-order (type two) variable-structure control which operates without high-frequency chattering. The proposed STSM scheme is a torque and stator......-gain sliding-mode-like behavior. The experimental tests show that the STSM-DTC controller displays very robust behavior, similar to a conventional sliding controller, and it works without notable steady-state chattering, like the PI controller. The paper presents theoretical aspects for the new STSM......-DTC control, design and implementation details, and relevant experimental results for a sensorless IM drive. The scheme is compared to a second-order sliding mode controller and a linear PI controller. A robustness assessment against the PI controller is also included....
Sensorless sliding mode torque control of an IPMSM drive based on active flux concept
A.A. Hassan
2012-03-01
Full Text Available This paper investigates a novel direct torque control of a sensorless interior permanent magnet synchronous motor based on a sliding mode technique. The speed and position of the interior permanent magnet synchronous motor are estimated online based on active flux concept. To overcome the large ripple content associated with the direct torque, a torque/flux sliding mode controller has been employed. Two integral surface functions are used to construct the sliding mode controller. The command voltage is estimated from the torque and flux errors based on the two switching functions. The idea of the total sliding mode is used to eliminate the problem of reaching phase stability. The space vector modulation is combined with the sliding mode controller to ensure minimum torque and flux ripples and provides high resolution voltage control. The proposed scheme has the advantages of simple implementation, and does not require an external signal injection. In addition, it combines the merits of the direct torque control, sliding mode controller, and space vector modulation besides to the sensorless control. Simulation works are carried out to demonstrate the ability of the proposed scheme at different operating conditions. The results confirm the high performance of the proposed scheme at standstill, low and high speeds including load disturbance and parameters variation.
New Technique of High-Performance Torque Control Developed for Induction Machines
Kenny, Barbara H.
2003-01-01
Two forms of high-performance torque control for motor drives have been described in the literature: field orientation control and direct torque control. Field orientation control has been the method of choice for previous NASA electromechanical actuator research efforts with induction motors. Direct torque control has the potential to offer some advantages over field orientation, including ease of implementation and faster response. However, the most common form of direct torque control is not suitable for the highspeed, low-stator-flux linkage induction machines designed for electromechanical actuators with the presently available sample rates of digital control systems (higher sample rates are required). In addition, this form of direct torque control is not suitable for the addition of a high-frequency carrier signal necessary for the "self-sensing" (sensorless) position estimation technique. This technique enables low- and zero-speed position sensorless operation of the machine. Sensorless operation is desirable to reduce the number of necessary feedback signals and transducers, thus improving the reliability and reducing the mass and volume of the system. This research was directed at developing an alternative form of direct torque control known as a "deadbeat," or inverse model, solution. This form uses pulse-width modulation of the voltage applied to the machine, thus reducing the necessary sample and switching frequency for the high-speed NASA motor. In addition, the structure of the deadbeat form allows the addition of the high-frequency carrier signal so that low- and zero-speed sensorless operation is possible. The new deadbeat solution is based on using the stator and rotor flux as state variables. This choice of state variables leads to a simple graphical representation of the solution as the intersection of a constant torque line with a constant stator flux circle. Previous solutions have been expressed only in complex mathematical terms without a
Vector control structure of an asynchronous motor at maximum torque
Chioncel, C. P.; Tirian, G. O.; Gillich, N.; Raduca, E.
2016-02-01
Vector control methods offer the possibility to gain high performance, being widely used. Certain applications require an optimum control in limit operating conditions, as, at maximum torque, that is not always satisfied. The paper presents how the voltage and the frequency for an asynchronous machine (ASM) operating at variable speed are determinate, with an accent on the method that keeps the rotor flux constant. The simulation analyses consider three load types: variable torque and speed, variable torque and constant speed, constant torque and variable speed. The final values of frequency and voltage are obtained through the proposed control schemes with one controller using the simulation language based on the Maple module. The dynamic analysis of the system is done for the case with P and PI controller and allows conclusions on the proposed method, which can have different applications, as the ASM in wind turbines.
Young, Aaron J; Gannon, Hannah; Ferris, Daniel P.
2017-01-01
Background Despite a large increase in robotic exoskeleton research, there are few studies that have examined human performance with different control strategies on the same exoskeleton device. Direct comparison studies are needed to determine how users respond to different types of control. The purpose of this study was to compare user performance using a robotic hip exoskeleton with two different controllers: a controller that targeted a biological hip torque profile and a proportional m...
On the use of positive feedback for improved torque control
Houman DALLALI; Gustavo A MEDRANO-CERDA; Michele FOCCHI; Thiago BOAVENTURA; Marco FRIGERIO; Claudio SEMINI; Jonas BUCHLI; Darwin G CALDWELL
2015-01-01
This paper considers the torque control problem for robots with flexible joints driven by electrical actuators. It is shown that the achievable closed-loop tracking bandwidth using PI torque controllers may be limited due to transmission zeros introduced by the load dynamics. This limitation is overcome by using positive feedback from the load motion in unison with PI torque controllers. The positive feedback is given in terms of load velocity, acceleration and jerk. Stability conditions for designing decentralized PI torque controllers are derived in terms of Routh-Hurwitz criteria. Disturbance rejection properties of the closed system are characterized and an analysis is carried out investigating the use of approximate positive feedback by omitting acceleration and/or jerk signals. The results of this paper are illustrated for a two DoF (degrees of freedom) system. Experimental results for a one DoF system are also included.
Design of direct drive robot using indigenously developed d.c. torque motors
Athani, Vithal V.
The range of high-performance torque motors, which were indigenously developed for use in multistage satellite launch vehicles, is described. The main features that set dc torque motors apart from dc servomotors are: high peak torque, power, and current over short periods of operation, low speed of operation, obviating the need for gearing, high torque/inertia and torque/weight ratios, and high figure of merit = torque/sq rt watt ratio. The dc torque motors are eminently suited to high-performance applications requiring high torque at low speed of operation, such as aircraft and missile control surface actuation, control of multistage satellite launch vehicles, certain computer peripherals like magnetic tape transports and hard disk drives, and robotics, CNC systems, and machine tool control.
Nozaki, Daichi; Nakazawa, Kimitaka; Akai, Masami
2005-09-01
In the single-joint torque exertion task, which has been widely used to control muscle activity, only the relevant joint torque is specified. However, the neglect of the neighboring joint could make the procedure unreliable, considering our previous result that even monoarticular muscle activity level is indefinite without specifying the adjacent joint torque. Here we examined the amount of hip joint torque generated with knee joint torque and its influence on the activity of the knee joint muscles. Twelve healthy subjects were requested to exert various levels of isometric knee joint torque. The knee and hip joint torques were obtained by using a custom-made device. Because no information about hip joint torque was provided to the subjects, the hip joint torque measured here was a secondary one associated with the task. The amount of hip joint torque varied among subjects, indicating that they adopted various strategies to achieve the task. In some subjects, there was a considerable internal variability in the hip joint torque. Such variability was not negligible, because the knee joint muscle activity level with respect to the knee joint torque, as quantified by surface electromyography (EMG), changed significantly when the subjects were requested to change the strategy. This change occurred in a very systematic manner: in the case of the knee extension, as the hip flexion torque was larger, the activity of mono- and biarticular knee extensors decreased and increased, respectively. These results indicate that the conventional single knee joint torque exertion has the drawback that the intersubject and/or intertrial variability is inevitable in the relative contribution among mono- and biarticular muscles because of the uncertainty of the hip joint torque. We discuss that the viewpoint that both joint torques need to be considered will bring insights into various controversial problems such as the shape of the EMG-force relationship, neural factors that help
Fuzzy-PI Torque and Flux Controllers for DTC with Multilevel Inverter of Induction Machines
Norjulia Mohamad Nordin
2014-10-01
Full Text Available In this paper the performance of flux and torque controller for a Direct Torque Control of Cascaded H-bridge Multilevel Inverter (DTC-CMLI fed induction machines are investigated. A Fuzzy-PI with fixed switching frequency is proposed for both torque and flux controller to enhance the DTC-CMLI performance. The operational concepts of the Fuzzy-PI with the fixed switching frequency controller of a DTC-MLI system followed by the simulation results and analysis are presented. The performance of the proposed system is verified via MATLAB/Simulink©. The proposed system significantly improves the DTC drive in terms of dynamic performance, smaller torque and flux ripple, and lower total harmonic distortion (THD.
Aaron J. Young
2017-06-01
Full Text Available BackgroundDespite a large increase in robotic exoskeleton research, there are few studies that have examined human performance with different control strategies on the same exoskeleton device. Direct comparison studies are needed to determine how users respond to different types of control. The purpose of this study was to compare user performance using a robotic hip exoskeleton with two different controllers: a controller that targeted a biological hip torque profile and a proportional myoelectric controller.MethodsWe tested both control approaches on 10 able-bodied subjects using a pneumatically powered hip exoskeleton. The state machine controller targeted a biological hip torque profile. The myoelectric controller used electromyography (EMG of lower limb muscles to produce a proportional control signal for the hip exoskeleton. Each subject performed two 30-min exoskeleton walking trials (1.0 m/s using each controller and a 10-min trial with the exoskeleton unpowered. During each trial, we measured subjects’ metabolic cost of walking, lower limb EMG profiles, and joint kinematics and kinetics (torques and powers using a force treadmill and motion capture.ResultsCompared to unassisted walking in the exoskeleton, myoelectric control significantly reduced metabolic cost by 13% (p = 0.005 and biological hip torque control reduced metabolic cost by 7% (p = 0.261. Subjects reduced muscle activity relative to the unpowered condition for a greater number of lower limb muscles using myoelectric control compared to the biological hip torque control. More subjects subjectively preferred the myoelectric controller to the biological hip torque control.ConclusionMyoelectric control had more advantages (metabolic cost and muscle activity reduction compared to a controller that targeted a biological torque profile for walking with a robotic hip exoskeleton. However, these results were obtained with a single exoskeleton device with specific
Young, Aaron J; Gannon, Hannah; Ferris, Daniel P
2017-01-01
Despite a large increase in robotic exoskeleton research, there are few studies that have examined human performance with different control strategies on the same exoskeleton device. Direct comparison studies are needed to determine how users respond to different types of control. The purpose of this study was to compare user performance using a robotic hip exoskeleton with two different controllers: a controller that targeted a biological hip torque profile and a proportional myoelectric controller. We tested both control approaches on 10 able-bodied subjects using a pneumatically powered hip exoskeleton. The state machine controller targeted a biological hip torque profile. The myoelectric controller used electromyography (EMG) of lower limb muscles to produce a proportional control signal for the hip exoskeleton. Each subject performed two 30-min exoskeleton walking trials (1.0 m/s) using each controller and a 10-min trial with the exoskeleton unpowered. During each trial, we measured subjects' metabolic cost of walking, lower limb EMG profiles, and joint kinematics and kinetics (torques and powers) using a force treadmill and motion capture. Compared to unassisted walking in the exoskeleton, myoelectric control significantly reduced metabolic cost by 13% (p = 0.005) and biological hip torque control reduced metabolic cost by 7% (p = 0.261). Subjects reduced muscle activity relative to the unpowered condition for a greater number of lower limb muscles using myoelectric control compared to the biological hip torque control. More subjects subjectively preferred the myoelectric controller to the biological hip torque control. Myoelectric control had more advantages (metabolic cost and muscle activity reduction) compared to a controller that targeted a biological torque profile for walking with a robotic hip exoskeleton. However, these results were obtained with a single exoskeleton device with specific control configurations while level walking at a
Remote control canard missile with a free-rolling tail brake torque system
Blair, A. B., Jr.
1981-01-01
An experimental wind-tunnel investigation has been conducted at supersonic Mach numbers to determine the static aerodynamic characteristics of a cruciform canard-controlled missile with fixed and free-rolling tail-fin afterbodies. Mechanical coupling effects of the free-rolling tail afterbody were investigated using an electronic/electromagnetic brake system that provides arbitrary tail-fin brake torques with continuous measurements of tail-to-mainframe torque and tail-roll rate. Results are summarized to show the effects of fixed and free-rolling tail-fin afterbodies that include simulated measured bearing friction torques on the longitudinal and lateral-directional aerodynamic characteristics.
Torque Control of a Separate-Winding Excitation DC Motor for a Dynamometer
2010-12-01
In this thesis, the theory behind a separate-winding excitation direct current ( DC ) motor and profile of the motor’s torque versus rotor speed is... DC motor is proportional to the armature current. From this theory, a program was written in Simulink with Xilinx embedded software to enable a user...to command the DC motor torque through a Graphical User Interface (GUI). The command is then converted to control armature current through a Field
Torque-stiffness-controlled dynamic walking with central pattern generators.
Huang, Yan; Vanderborght, Bram; Van Ham, Ronald; Wang, Qining
2014-12-01
Walking behavior is modulated by controlling joint torques in most existing passivity-based bipeds. Controlled Passive Walking with adaptable stiffness exhibits controllable natural motions and energy efficient gaits. In this paper, we propose torque-stiffness-controlled dynamic bipedal walking, which extends the concept of Controlled Passive Walking by introducing structured control parameters and a bio-inspired control method with central pattern generators. The proposed walking paradigm is beneficial in clarifying the respective effects of the external actuation and the internal natural dynamics. We present a seven-link biped model to validate the presented walking. Effects of joint torque and joint stiffness on gait selection, walking performance and walking pattern transitions are studied in simulations. The work in this paper develops a new solution of motion control of bipedal robots with adaptable stiffness and provides insights of efficient and sophisticated walking gaits of humans.
许桢
2012-01-01
This paper uses Simulink/WPower System, use structured and modular method of asynchronous motor, variable frequency speed regulation System, models and simulation, according to PWM inverter power supply of induction motor drive direct torque control variable frequency speed regulation System, under the characteristics of the Matlab environment, and introduces the method to construct the son modules and functions. The construction of the simulation model and the practical variable frequency speed regulation system for high performance, are close to the asynchronous motor speed control system design and commissioning provides a good inspection means and achieve. It is simple and convenient, easy to modify the model, and the simulation results verify the effectiveness of the method.%针对PWM逆变器供电驱动的异步电机直接转矩控制变频调速系统的特点,在Matlah环境下,利用Simulink/Power System,采用结构化和模块化的方法,对异步电机变频调速系统进行了建模和仿真,并详细介绍了各子模块的构造方法及功能.构建的仿真模型与实际变频调速系统比较接近,为高性能的异步电机变频调速控制系统地设计与调试提供了一种较好的检验手段,且实现简单,便于修改.仿真结果验证了建模方法的有效性.
High-Accuracy and Fast-Response Flywheel Torque Control
Xinxiu Zhou
2014-01-01
Full Text Available Compared with current mode flywheel torque controller, speed mode torque controller has superior disturbance rejection capability. However, the speed loop delay reduces system dynamic response speed. To solve this problem, a two-degrees-of-freedom controller (2DOFC which consists of a feedback controller (FBC and a command feedforward controller (FFC is proposed. The transfer function of FFC is found based on the inverse model of motor drive system, whose parameters are identified by recursive least squares (RLS algorithm in real-time. Upon this, Kalman filter with softening factor is introduced for the improved parameters identification and torque control performances. Finally, the validity and the superiority of the proposed control scheme are verified through experiments with magnetically suspended flywheel (MSFW motor.
Controlling torque and cutting costs: steerable drill bits deliver in Latin America
Barton, Steve; Garcia, Alexis; Amorim, Dalmo [ReedHycalog, Stonehouse (United Kingdom); Iramina, Wilson [University of Sao Paulo (USP), SP (Brazil); Herrera, Gabriel
2008-07-01
Tool face Control is widely regarded as one of the greatest directional drilling challenges with a Fixed Cutter (FC) drill bit on a Steerable Motor assembly. Tool face offset is proportional to the torque generated by the bit, and by nature, FC bits are capable of generating high levels of torque. If large changes in downhole torque are produced while drilling, this will cause rotation of the drill string, and loss of tool face orientation. This results in inefficient drilling and increases risk of bit and downhole tool damage. This paper examines the effect of various FC drill bit components to determine the key design requirements to deliver a smooth torque response and an improved directional performance. Included is a review of the results from comprehensive laboratory testing to determine the effectiveness of a number of different configurations of removable Torque Controlling Components (TCC). These, in combination with specific cutting structure layouts, combine to provide predictable torque response while optimized for high rates of penetration. In addition, unique gauge geometry is disclosed that was engineered to reduce drag and deliver improved borehole quality. This gauge design produces less torque when sliding and beneficial gauge pad interaction with the borehole when in rotating mode. Field performance studies from within Latin America clearly demonstrate that matching TCC, an optimized cutting structure, and gauge geometry to a steerable assembly delivers smooth torque response and improved directional control. Benefits with regard to improved stability are also discussed. Successful application has resulted in significant time and cost savings for the operator, demonstrating that Stability and Steerability improvements can be achieved with an increase in penetration rate. (author)
Minimization of Torque Ripple in DTC of Induction Motor Using Fuzzy Mode Duty Cycle Controller
Turki Y. Abdalla
2011-06-01
Full Text Available Among all control methods for induction motor drives, Direct Torque Control (DTC seems to be particularly interesting being independent of machine rotor parameters and requiring no speed or position sensors. The DTC scheme is characterized by the absence of PI regulators, coordinate transformations, current regulators and PWM signals generators. In spite of its simplicity, DTC allows a good torque control in steady state and transient operating conditions to be obtained. However, the presence of hysterics controllers for flux and torque could determine torque and current ripple and variable switching frequency operation for the voltage source inverter. This paper is aimed to analyze DTC principles, and the problems related to its implementation, especially the torque ripple and the possible improvements to reduce this torque ripple by using a proposed fuzzy based duty cycle controller. The effectiveness of the duty ratio method was verified by simulation using Matlab/Simulink software package. The results are compared with that of the traditional DTC models.
Design and analysis of a direct-drive wind power generator with ultra-high torque density
Jian, Linni; Shi, Yujun; Wei, Jin; Zheng, Yanchong
2015-05-01
In order to get rid of the nuisances caused by mechanical gearboxes, generators with low rated speed, which can be directly connected to wind turbines, are attracting increasing attention. The purpose of this paper is to propose a new direct-drive wind power generator (DWPG), which can offer ultra-high torque density. First, magnetic gear (MG) is integrated to achieve non-contact torque transmission and speed variation. Second, armature windings are engaged to achieve electromechanical energy conversion. Interior permanent magnet (PM) design on the inner rotor is adopted to boost the torque transmission capability of the integrated MG. Nevertheless, due to lack of back iron on the stator, the proposed generator does not exhibit prominent salient feature, which usually exists in traditional interior PM (IPM) machines. This makes it with good controllability and high power factor as the surface-mounted permanent magnet machines. The performance is analyzed using finite element method. Investigation on the magnetic field harmonics demonstrates that the permanent-magnetic torque offered by the MG can work together with the electromagnetic torque offered by the armature windings to balance the driving torque captured by the wind turbine. This allows the proposed generator having the potential to offer even higher torque density than its integrated MG.
Torque- and Speed Control of a Pitch Regulated Wind Turbine
Rasila, Mika
2003-07-01
Variable speed operated wind turbines has the potential to reduce fatigue loads, compared to fixed speed wind turbines. With pitch controllable rotor blades limitation of the power at high wind speeds is obtained. The thesis describes different controlling aspects concerning wind turbines and how these together can be used to optimize the system's performance. Torque control is used in order to achieve reduction on the mechanical loads on the drive-train for low wind speeds and limitation of power output for high wind speeds. In the high wind speed interval torque control is effective in order to limit the output power if a sufficiently fast pitch actuator is used. In the middle wind speed interval filter utilization can be used to give a reference signal to the controller in order to reduce speed and torque variations.
Lascu, Christian; Boldea, Ion; Blaabjerg, Frede
2013-01-01
This paper investigates a permanent magnet synchronous motor drive controlled by a second-order variable structure control technique, known as the super-twisting sliding modes (STSM) control. The STSM controller is designed as a direct torque and flux controller and it works in the stator flux...... reference frame, rather than the rotor frame, as a regular vector control scheme. Another second-order sliding mode controller (SMC) was developed and compared with the STSM controller. Also for comparison, a similar direct torque control scheme based on linear PI controllers was developed and tested....... The tests show that the STSM controller displays very robust behavior, like any SMC, and it works without notable chattering, like the linear PI-based controller. The paper presents theoretical aspects for the STSM control, several design and implementation details, and comparative experimental results...
RESEARCH ON CONTROL METHOD OF HYDRAULIC TORQUE SIMULATOR
无
2001-01-01
An effective controller and compensator is designed by using the system identification and constant structure theory to realize the effective control. The experimental results indicate the extraneous torque can be decreased by 90% and the characteristics can be improved greatly by means of this kind of method.
Path-constrained robot control with limited torques -- Experimental evaluation
Dahl, O. (Lund Univ., Malmoe (Sweden))
1994-10-01
Fast motion along a predefined path is important in many robot applications, and requires utilization of the maximum allowable torque range. If the torque is at the limit, there is no margin to cope with disturbances or modeling errors, which may result in deviation from the path. A path velocity controller for modification of the velocity along the path when the torques saturate can improve path tracking. The path velocity controller acts as an outer feedback loop outside the ordinary robot controller, and modifies a nominal velocity profile, computed by minimum time optimization using available methods. An experimental evaluation of such a controller is presented. The experiments are done on an industrial robot, where the original robot control system has been replaced by a VME-based computer system. The experimental results demonstrate that the path velocity controller can adjust a nominal minimum time velocity profile, such that the result is good path following and good utilization of the available torque range. It is also demonstrated how the path velocity controller is able to compensate for time variations in the robot dynamics.
Torque Control of Underactuated Tendon-driven Robotic Fingers
Abdallah, Muhammad E. (Inventor); Ihrke, Chris A. (Inventor); Reiland, Matthew J. (Inventor); Wampler, Charles W. (Inventor); Diftler, Myron A. (Inventor); Platt, Robert (Inventor); Bridgwater, Lyndon (Inventor)
2013-01-01
A robotic system includes a robot having a total number of degrees of freedom (DOF) equal to at least n, an underactuated tendon-driven finger driven by n tendons and n DOF, the finger having at least two joints, being characterized by an asymmetrical joint radius in one embodiment. A controller is in communication with the robot, and controls actuation of the tendon-driven finger using force control. Operating the finger with force control on the tendons, rather than position control, eliminates the unconstrained slack-space that would have otherwise existed. The controller may utilize the asymmetrical joint radii to independently command joint torques. A method of controlling the finger includes commanding either independent or parameterized joint torques to the controller to actuate the fingers via force control on the tendons.
A New Torque Control System of Permanent Magnet Synchronous Motor
Evstratov Andrey
2017-01-01
Full Text Available The article describes a new approach to control of permanent magnet synchronous motor drive based on the analysis of the electromechanical transformation. The proposed control system provides quick response and low ripple of the motor torque and flux. To synthesis this control system, the authors put the electromagnetic torque and the modulus of stator flux vector as controlled values and use the Lyapunov’s second method. In addition, the stator voltage constriction and ability of low-pass filtration are taken into account. The investigation of the proposed control system has carried out with the simulation and the experimental research which have confirmed that the proposed control system correspond to all above-mentioned control tasks and the permanent magnet synchronous motor controlled under this system may be recommended to use in robotics.
张凤阁; 金石; 张武
2011-01-01
A maximal power tracking method through controlling torque and power factor of brushless doubly-fed wind power generator to regulate active power is proposed based on direct torque control （DTC）, according to the power output characteristics of wind turbine. Considering the complicated relation of internal magnetic fields of brushless doubly-fed generator（BDFG）, a novel speed observer is designed by estimating the rotor flux synchronous rotating speed and slip speed to improve the reliability of wind power generation system in harsh wind field environment. Furthermore, the model reference adaptive identification technology is adopted to design control winding flux observer in order to enhance the accuracy of estimated flux within wide speed range and further to improve the operation performance of the DTC system at the low frequency of the control winding. Simulation results prove the validity and feasibility of the proposed novel speed estimation method and DTC scheme.%根据风力机的功率输出特性，针对无刷双馈风力发电机，提出了一种基于直接转矩控制方法控制发电机转矩和功率因数来调节有功功率的最大功率跟踪方法。为了提高风电系统的可靠性，使系统更能适用于恶劣的风场环境，本文针对无刷双馈发电机复杂的内部磁场关系，设计了一种新型速度观测器，通过估算转子磁链同步旋转速度和转差速度来获得发电机转速。此外，还采用模型参考自适应辨识技术来设计控制绕组磁链观测器，以提高无刷双馈发电机在全速范围内磁链估计的准确性，进而改善直接转矩控制系统在控制绕组侧低频时的运行性能。仿真结果验证了所提出的新型转速估算方法的正确性和直接转矩控制方案的可行性。
Torque control of underactuated tendon-driven fingers
M. E. Abdallah
2011-02-01
Full Text Available Given an underactuated tendon-driven finger, the finger posture is underdetermined and can move freely ("flop" in a region of slack tendons. This work shows that such an underactuated finger can be operated in tendon force control (rather than position control with effective performance. The force control eliminates the indeterminate slack while commanding a parameterized space of desired torques. The torque will either push the finger to the joint limits or wrap around an external object with variable torque – behavior that is sufficient for primarily gripping fingers. In addition, introducing asymmetric joint radii to the design allows the finger to command an expanded range of joint torques and to scan an expanded set of external surfaces. This study is motivated by the design and control of the secondary fingers of the NASA-GM R2 humanoid hand.
This paper was presented at the IFToMM/ASME International Workshop on Underactuated Grasping (UG2010, 19 August 2010, Montréal, Canada.
Control of fracture reduction robot using force/torque measurement.
Douke, T; Nakajima, Y; Mori, Y; Onogi, S; Sugita, N; Mitsuishi, M; Bessho, M; Ohhashi, S; Tobita, K; Ohnishi, I; Sakuma, I; Dohi, T; Maeda, Y; Koyama, T; Sugano, N; Yonenobu, K; Matsumoto, Y; Nakamura, K
2008-01-01
We have developed a surgical robotic system for femoral fracture reduction employing indirect traction. Indirect traction in fracture reduction is a generally used surgical method for preventing complications such as bone splits caused by high stress on bones. For traction, a patient's foot is gripped by a jig and pulled to the distal side. Indirect traction has the advantage of distributing bone stress by utilizing a strong traction force; however, this procedure does not accurately control the proper positioning of fractured fragments when a surgical robot is used. The human leg has knee and an ankle joints, and thus robotic motion presents problems in not being able to directly propagate reduction motion to a fractured femoral fragment, rendering control of bone position difficult. We propose a control method for fracture reduction robots using external force/torque measurements of the human leg to achieve precise fracture reduction. Results showed that the proposed method reduced repositioning error from 6.8 mm and 15.9 degrees to 0.7 mm and 5.3 degrees, respectively.
Asmussen, M J; Bailey, A Z; Nelson, A J
2015-12-17
The neural command required to coordinate a multi-joint movement is inherently complex. During multi-joint movement of the limb, the force created from movement at one joint may create a torque at a second joint known as an interaction torque. Interaction torques may be assistive or resistive thereby aiding or opposing the motion of the second joint, respectively. For movement to be effectively controlled, the central nervous system should modulate neural output to the muscles to appropriately account for interaction torques. The present study examined the neural output from the primary motor cortex before and during reaching movements that required different combinations of assistive and resistive interaction torques occurring at the shoulder and elbow joints. Using transcranial magnetic stimulation to probe neural output from the primary motor cortex, results indicate that corticospinal output controlling the upper arm is related to resistive interaction torques occurring at the shoulder joint. Further, cortical output to bi-articular muscles is associated with interaction torque and this may be driven by the fact that these muscles are in an advantageous position to control torques produced between inter-connection segments. Humans have a tendency to avoid reaching movements that involve resistive interaction torques and this may be driven by the requirement of increased neural output associated with these movements.
Electromagnetic tweezers with independent force and torque control
Jiang, Chang; Lionberger, Troy A.; Wiener, Diane M.; Meyhofer, Edgar
2016-08-01
Magnetic tweezers are powerful tools to manipulate and study the mechanical properties of biological molecules and living cells. In this paper we present a novel, bona fide electromagnetic tweezer (EMT) setup that allows independent control of the force and torque applied via micrometer-sized magnetic beads to a molecule under study. We implemented this EMT by combining a single solenoid that generates force (f-EMT) with a set of four solenoids arranged into a symmetric quadrupole to generate torque (τ-EMT). To demonstrate the capability of the tweezers, we attached optically asymmetric Janus beads to single, tethered DNA molecules. We show that tension in the piconewton force range can be applied to single DNA molecules and the molecule can simultaneously be twisted with torques in the piconewton-nanometer range. Furthermore, the EMT allows the two components to be independently controlled. At various force levels applied to the Janus bead, the trap torsional stiffness can be continuously changed simply by varying the current magnitude applied to the τ-EMT. The flexible and independent control of force and torque by the EMT makes it an ideal tool for a range of measurements where tensional and torsional properties need to be studied simultaneously on a molecular or cellular level.
Fuzzy Backstepping Torque Control Of Passive Torque Simulator With Algebraic Parameters Adaptation
Ullah, Nasim; Wang, Shaoping; Wang, Xingjian
2015-07-01
This work presents fuzzy backstepping control techniques applied to the load simulator for good tracking performance in presence of extra torque, and nonlinear friction effects. Assuming that the parameters of the system are uncertain and bounded, Algebraic parameters adaptation algorithm is used to adopt the unknown parameters. The effect of transient fuzzy estimation error on parameters adaptation algorithm is analyzed and the fuzzy estimation error is further compensated using saturation function based adaptive control law working in parallel with the actual system to improve the transient performance of closed loop system. The saturation function based adaptive control term is large in the transient time and settles to an optimal lower value in the steady state for which the closed loop system remains stable. The simulation results verify the validity of the proposed control method applied to the complex aerodynamics passive load simulator.
Direct Torque Control System based on Neural Network Speed Recognization%基于神经网络速度辨识的直接转矩控制系统
刘文胜; 王一; 王新伟
2007-01-01
介绍了一种采用电压空间矢量脉宽调制(Space Vector PWM,简称SVPWM)的新型直接转矩控制(Direct Torque Control,简称DTC)系统.针对DTC系统存在的低速时转矩脉动问题,将电压空间矢量与DTC技术相结合,用PI调节的方法取代了传统DTC系统中采用的滞环控制,提出了一种基于SVPWM的DTC方法.在SVPWM-DTC系统中采用了神经网络速度辨识器,通过神经网络对电机的定、转子磁链和转速进行在线辨识.实验结果表明,这种新型DTC系统有着良好的动、静态性能和全速范围的调速精度.
李兴友; 李彦
2012-01-01
The structure and characteristics of ship electric propulsion system are introduced. The principle of direct torque control(DTC) based on space vector modulation(SVM) is analyzed. The compute method of expect voltage vector and ship-airscrew model are introduced, and the simulation model of ship electric propulsion system DTC in Matlab/Simulink environment is constructed. The simulation results indicate that the performance of the propulsion system is improved with the application of DTC based on SVM.%介绍了船舶电力推进系统的结构和特点；分析了基于空间矢量调制(SVM)直接转矩控制(DTC)的原理；介绍求取预期电压矢量的方法以及船舶的船-桨模型；在Matlab/Simulink搭建了船舶电力推进DTC仿真模型.仿真结果表明基于SVM的DTC可以提高船舶电力推进系统的性能.
Virtual Passive Controller for Robot Systems Using Joint Torque Sensors
Aldridge, Hal A.; Juang, Jer-Nan
1997-01-01
This paper presents a control method based on virtual passive dynamic control that will stabilize a robot manipulator using joint torque sensors and a simple joint model. The method does not require joint position or velocity feedback for stabilization. The proposed control method is stable in the sense of Lyaponov. The control method was implemented on several joints of a laboratory robot. The controller showed good stability robustness to system parameter error and to the exclusion of nonlinear dynamic effects on the joints. The controller enhanced position tracking performance and, in the absence of position control, dissipated joint energy.
Dallmann, Chris J; Dürr, Volker; Schmitz, Josef
2016-01-27
Determining the mechanical output of limb joints is critical for understanding the control of complex motor behaviours such as walking. In the case of insect walking, the neural infrastructure for single-joint control is well described. However, a detailed description of the motor output in form of time-varying joint torques is lacking. Here, we determine joint torques in the stick insect to identify leg joint function in the control of body height and propulsion. Torques were determined by measuring whole-body kinematics and ground reaction forces in freely walking animals. We demonstrate that despite strong differences in morphology and posture, stick insects show a functional division of joints similar to other insect model systems. Propulsion was generated by strong depression torques about the coxa-trochanter joint, not by retraction or flexion/extension torques. Torques about the respective thorax-coxa and femur-tibia joints were often directed opposite to fore-aft forces and joint movements. This suggests a posture-dependent mechanism that counteracts collapse of the leg under body load and directs the resultant force vector such that strong depression torques can control both body height and propulsion. Our findings parallel propulsive mechanisms described in other walking, jumping and flying insects, and challenge current control models of insect walking. © 2016 The Author(s).
Wireless control and selection of forces and torques - towards wireless engines
Boyvat, M.; Hafner, C.; Leuthold, J.
2014-07-01
Powering and manipulating translational and rotational motions of objects wirelessly, and controlling several objects independently is of significant importance in numerous fields such as robotics, medicine, biology, fluid dynamics, optics. We propose a method based on coupled LC resonators, to control objects selectively by steering the frequency of an external magnetic field. This concept does not need any magnetic materials and it brings a rich variety of features concerning forces and torques. We theoretically and experimentally show that the forces can be enhanced by the interaction of resonators and that both direction and magnitude of forces can be controlled by the frequency of the applied external magnetic field. Moreover, we demonstrate interesting rotational effects, such as bi-directionally controllable torques, controllable stable orientations, and spinning, which leads to a wirelessly powered motor.
杨杰; 黄坤
2013-01-01
针对基于PI控制器的永磁同步电动机直接转矩控制系统存在转矩波动大、易受负载变化影响的问题,设计了一种基于转速外环的自抗扰控制器,代替PI控制器以改善永磁同步电动机直接转矩控制系统的性能；采用粒子群优化算法对自抗扰控制器的相关参数进行了优化计算,改进了控制器的调节性能.仿真和实验结果表明,基于参数优化自抗扰控制器的永磁同步电动机直接转矩控制系统具有较高的抗负载扰动能力,更快的响应速度和良好的动、静态性能.%In view of problems of big torque fluctuation and easy to be influenced by load change existed in direct torque control system of permanent magnet synchronous motor based on PI controller,the paper designed an active disturbance rejection controller based on speed loop to replace PI controller to improve performances of direct torque control system of permanent magnet synchronous motor.It used particle swarm optimizer algorithm to make optimization calculation for the parameters of the active disturbance rejection controller and improved adjustment performance of the controller.The simulation and experimental results show that the system based on the active disturbance rejection controller with parameters optimization has higher ability of anti-disturbance of load,faster response speed and good dynamic and static performance.
Sivachandran Paulsamy
2014-01-01
Full Text Available In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG for direct coupled stand alone wind energy systems (SAWES. Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.
Paulsamy, Sivachandran
2014-01-01
In wind energy systems employing permanent magnet generator, there is an imperative need to reduce the cogging torque for smooth and reliable cut in operation. In a permanent magnet generator, cogging torque is produced due to interaction of the rotor magnets with slots and teeth of the stator. This paper is a result of an ongoing research work that deals with various methods to reduce cogging torque in dual rotor radial flux permanent magnet generator (DRFPMG) for direct coupled stand alone wind energy systems (SAWES). Three methods were applied to reduce the cogging torque in DRFPMG. The methods were changing slot opening width, changing magnet pole arc width and shifting of slot openings. A combination of these three methods was applied to reduce the cogging torque to a level suitable for direct coupled SAWES. Both determination and reduction of cogging torque were carried out by finite element analysis (FEA) using MagNet Software. The cogging torque of DRFPMG has been reduced without major change in induced emf. A prototype of 1 kW, 120 rpm DRFPMG was fabricated and tested to validate the simulation results. The test results have good agreement with the simulation predictions.
Closed-loop torque feedback for a universal field-oriented controller
De Doncker, Rik W. A. A.; King, Robert D.; Sanza, Peter C.; Haefner, Kenneth B.
1992-01-01
A torque feedback system is employed in a universal field-oriented (UFO) controller to tune a torque-producing current command and a slip frequency command in order to achieve robust torque control of an induction machine even in the event of current regulator errors and during transitions between pulse width modulated (PWM) and square wave modes of operation.
王莹; 胡育文; 杨建飞
2011-01-01
在以往的永磁同步电机直接转矩控制研究中,将零电压矢量引入到转矩调节器中,认为其起到保持当前转矩的作用.该文对永磁同步电机中零电压矢量对转矩脉动和磁链脉动的影响进行了详细的理论分析,指出在电机高速运行的情况下,零矢量实际是起到减小转矩的作用.转速越高,零矢量减小转矩的效果越明显.仿真结果证明了理论分析的正确性,这为正确理解零矢量在永磁同步电机直接转矩控制的作用以及今后对零矢量作用的范围进行优化设计具有指导意义.%In previous study of permanent magnet synchronous motor direct torque control ( PMSM DTC ) , considered to keep the torque stable, zero voltage vector was introduced into the torque controller. The influence of zero voltage vector on flux and torque ripple in PMSM DTC. Was analyzed detailedly in this paper. And it pointed out that, when the motor run with a high speed, zero voltage vector actually reduced the torque. The higher the rotor speed was, the more obvious the effect of reducing the torque was. The simulation result verified the validity of the theory analysis. It is a significant guide for understanding correctly the function of zero voltage vector in PMSM DTC and optimizing the design of zero voltage vector working zone in the future.
DTC-SVM Based on PI Torque and PI Flux Controllers to Achieve High Performance of Induction Motor
Hassan Farhan Rashag
2014-01-01
Full Text Available The fundamental idea of direct torque control of induction machines is investigated in order to emphasize the property produced by a given voltage vector on stator flux and torque variations. The proposed control system is based on Space Vector Modulation (SVM of electrical machines, Improvement model reference adaptive system, real time of stator resistance and estimation of stator flux. The purpose of this control is to minimize electromagnetic torque and flux ripple and minimizing distortion of stator current. In this proposed method, PI torque and PI flux controller are designed to achieve estimated torque and flux with good tracking and fast response with reference torque and there is no steady state error. In addition, design of PI torque and PI flux controller are used to optimize voltages in d-q reference frame that applied to SVM. The simulation Results of proposed DTC-SVM have complete excellent performance in steady and transient states as compared with classical DTC-SVM.
Hida, Hajime; Tomigashi, Yoshio; Kishimoto, Keiji
High efficiency drive can be achieved by the maximum torque-per-ampere (MTPA) control which used reluctance torque effectively. However, the calculations for estimating rotor position and for controlling the d-axis current are required. The motor parameters of inductance etc. that are easily affected by magnetic saturation are included in those calculations. This paper proposes a new MTPA control method, which is robust against changes of motor parameters caused by magnetic saturation. In addition, complex calculation for d-axis current or reference to the table is not necessary. In this method, we define a novel coordinate frame, which has one axis aligned with the current vector of the MTPA control, and estimate the frame directly. Because the parameter Lqm for estimating the frame is less affected by the magnetic saturation than the conventional Lq, the effect of magnetic saturation on the position estimation can be greatly suppressed. First, an extended electromotive force model based on the proposed frame and a parameter Lqm for an estimation of the frame are derived. Next, the effectiveness of this proposed method is confirmed by simulations and experiments.
徐艳平; 钟彦儒
2009-01-01
永磁同步电机传统直接转矩控制在电机低速运行时存在着转矩脉动大、开关频率不恒定等问题,本文在详细分析影响磁链和转矩脉动大小因素的基础上,提出了一种准确确定占空比大小的永磁同步电机新型直接转矩控制方法.该方法基于精确的数学模型利用转矩误差计算出当前所选有效电压矢量的作用时间在整个采样周期中的占空比,实时地调整有效电压矢量的作用时间.仿真和实验结果表明,基于占空比控制的永磁同步电机直接转矩控制在保持传统直接转矩控制优点的基础上,能够有效减小转矩脉动,改善了传统直接转矩控制系统性能.%Disadvantages of traditional direct torque control (DTC) systems for permanent magnet synchronous motors (PMSM) are high torque ripples and inconstant switching frequency at low speed. A novel DTC strategy of PMSM combined with exact duty ratio calculation is proposed based on the detailed analysis of effects factors of flux linkage and torque ripples. In this method the duty ratio between the action time of effective voltage vector and the sampling period is calculated according to torque errors based on exact mathematical models and the action time of active voltage vectors is adjusted. Simulation and experimental results show that the new DTC strategy based on duty ratio control has advantages of traditional DTC and effectively reduces torque ripples which improve the performance of traditional DTC.
Low torque hydrodynamic lip geometry for bi-directional rotation seals
Dietle, Lannie L.; Schroeder, John E.
2009-07-21
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
Investigation of torque control using a variable slip induction generator
Bossanyi, E.A.; Gamble, C.R.
1991-07-01
An investigation of the possibilities of using a variable slip induction generator to control wind turbine transmission torque has been carried out. Such a generator consists of a wound rotor induction generator with its rotor winding connected to an external variable resistance circuit. By controlling the external resistance, the torque-slip characteristic of the generator can be modified, allowing efficient, low-slip operation below rated wind speed and compliant, high-slip operation above rated, where the additional losses are of no consequence but the resulting compliance allows a much reduced duty to be specified for the transmission and gearbox. A number of hardware options have been investigated for the variable resistance rotor circuit, the main options being either a rectifier and DC chopper or an AC regulator. Both of these options use semiconductor switching devices, for which the relative merits of thyristors, MOSFETs, GTOs and transistors have been investigated. A favoured scheme consisting of an AC regulator using GTOs has been provisionally selected. This choice uses some non-standard equipment but is expected to give negligible problems with harmonics. A comprehensive simulation model has been set up and used to investigate the behaviour of the whole system. (author).
Torque Control of a Rehabilitation Teaching Robot Using Magneto-Rheological Fluid Clutches
Hakogi, Hokuto; Ohaba, Motoyoshi; Kuramochi, Naimu; Yano, Hidenori
A new robot that makes use of MR-fluid clutches for simulating torque is proposed to provide an appropriate device for training physical therapy students in knee-joint rehabilitation. The feeling of torque provided by the robot is expected to correspond to the torque performance obtained by physical therapy experts in a clinical setting. The torque required for knee-joint rehabilitation, which is a function of the rotational angle and the rotational angular velocity of a knee movement, is modeled using a mechanical system composed of typical spring-mass-damper elements. The robot consists of two MR-fluid clutches, two induction motors, and a feedback control system. In the torque experiments, output torque is controlled using the spring and damper coefficients separately. The values of these coefficients are determined experimentally. The experimental results show that the robot would be suitable for training physical therapy students to experience similar torque feelings as needed in a clinical situation.
Displaceable spur gear torque controlled driver and method
Cook, Joseph S., Jr. (Inventor)
1994-01-01
Methods and apparatus are provided for a torque driver including a laterally displaceable gear support member to carry an output spur gear. A biasing assembly biases the output spur gear into engagement with a pinion to which is applied an input torque greater than a desired output torque limit for a threaded fastener such as a nut or screw. A coiled output linkage connects the output spur gear with a fastener adaptor which may be a socket for a nut. A gear tooth profile provides a separation force that overcomes the bias to limit torque at the desired torque limit. Multiple fasteners may be rotated simultaneously to a desired torque limit if additional output spur gears are provided. A gauged selector mechanism is provided to laterally displace multiple driver members for fasteners arranged in differing configurations. The torque limit is selectably adjustable and may be different for fasteners within the same fastener configuration.
Mehrdad Daryanush
2015-07-01
Full Text Available In the recent years, the use of switched reluctance motors (SRM in industrial applications has been increased. In this regard, a large amount of research studies have been conducted on controlling the speed and torque of the aforementioned motors. These motors not only have a simple and stable structure, but also production cost is low. In addition, these motors take advantage of great power, the ability to work in high speeds and inadequate environments (hot and dusty, reliability, control-ability, and high efficiency. However, discrete torque production of SRM along with enormous magnetic saturation in their cores reduces the variety of their industrial applications and also causes the inappropriate torque ripples. In this paper, a modified logical-rule-based method is proposed which employs the technique of controlling torque sharing function. Moreover, the optimized turn-on angle for conducting each phase is achieved by estimating the inductance curve in the vicinity of unaligned position and based on an analytical solution. Simulation results on a four-phase switched reluctance motor and a comparison with the conventional methods indicates validity and effectiveness of the proposed modified method.
Hackl, Christoph; Schechner, Korbinian
2016-09-01
We discuss non-ideal torque control in wind turbine systems. Most high-level controllers generate a reference torque which is then send to the underlying electrical drive system (generator+inverter) of the wind turbine system to steer the turbine/generator to its optimal operation point (depending on the wind speed). The energy production heavily depends on the mechanical power (i.e. the product of rotational speed and generator torque). However, since torque sensors in the MW range are not available or extremely expensive, the underlying torque control system is implemented as feedforward control and, therefore, is inherently sensitive to parameter variations/uncertainties. Based on real wind data and a wind turbine system model, we discuss causes and impacts of non-ideal feedforward torque control on the energy production and the annual gross earnings.
Research on Precision Assembly Robot's Joint Torque Control Based on Current Measurement
董高云; 许春山; 费燕琼; 赵锡芳
2003-01-01
A set of new current sensing device is used to realize joint torque control based on current measurement in a precision assembly robot's third joint. The output torque's model of the joint's brnshless DC motor is founded. Disturbance factors and the compensated effect of the torque's closed loop based on current measurement are analyzed. Related simulations and experiments show that the system has good current tracking and anti-disturbances performance, which improve the force control performance of the robot in assembly.
Pratik Y Chhatbar
Full Text Available Realization of reaching and grasping movements by a paralytic person or an amputee would greatly facilitate her/his activities of daily living. Towards this goal, control of a computer cursor or robotic arm using neural signals has been demonstrated in rodents, non-human primates and humans. This technology is commonly referred to as a Brain-Machine Interface (BMI and is achieved by predictions of kinematic parameters, e.g. position or velocity. However, execution of natural movements, such as swinging baseball bats of different weights at the same speed, requires advanced planning for necessary context-specific forces in addition to kinematic control. Here we show, for the first time, the control of a virtual arm with representative inertial parameters using real-time neural control of torques in non-human primates (M. radiata. We found that neural control of torques leads to ballistic, possibly more naturalistic movements than position control alone, and that adding the influence of position in a hybrid torque-position control changes the feedforward behavior of these BMI movements. In addition, this level of control was achievable utilizing the neural recordings from either contralateral or ipsilateral M1. We also observed changed behavior of hybrid torque-position control under novel external dynamic environments that was comparable to natural movements. Our results demonstrate that inclusion of torque control to drive a neuroprosthetic device gives the user a more direct handle on the movement execution, especially when dealing with novel or changing dynamic environments. We anticipate our results to be a starting point of more sophisticated algorithms for sensorimotor neuroprostheses, eliminating the need of fully automatic kinematic-to-dynamic transformations as currently used by traditional kinematic-based decoders. Thus, we propose that direct control of torques, or other force related variables, should allow for more natural
Stator-Flux Oriented Continuous Control of Torque in Induction Motors%异步电机按定子磁链定向的转矩连续控制
谢鸿鸣; 阮毅; 陈伯时
2000-01-01
This paper analyzes dynamic equivalent circuit of induction motor and the relationship among inner fluxes, then presents a direct stator flux oriented continuous torque control (DSFOCTC) scheme of induction motor , which uses stator current vector control instead of voltage vector control. As a combination of direct torque control (DTC) and flux-oriented vector control, it achieves round stator flux and continuous dynamic torque control resulting in less torque ripple than that in DTC. It reduces the dependence on rotor parameters, and is especially insensitive to rotor resistance. Finally, an induction motor speed control system incorporating this novel scheme is given and checked by simulation.
Shahnaz Tayebi Haghighi
2013-05-01
Full Text Available Design a nonlinear controller for second order nonlinear uncertain dynamical systems (e.g., internal combustion engine is one of the most important challenging works. This paper focuses on the comparative study between two important nonlinear controllers namely; computed torque controller (CTC and sliding mode controller (SMC and applied to internal combustion (IC engine in presence of uncertainties. In order to provide high performance nonlinear methodology, sliding mode controller and computed torque controller are selected. Pure SMC and CTC can be used to control of partly known nonlinear dynamic parameters of IC engine. Pure sliding mode controller and computed torque controller have difficulty in handling unstructured model uncertainties. To solve this problem applied linear error-based tuning method to sliding mode controller and computed torque controller for adjusting the sliding surface gain (λ and linear inner loop gain (K. Since the sliding surface gain (λ and linear inner loop gain (K are adjusted by linear error-based tuning method. In this research new λ and new K are obtained by the previous λ and K multiple gains updating factor(α. The results demonstrate that the error-based linear SMC and CTC are model-based controllers which works well in certain and uncertain system. These controllers have acceptable performance in presence of uncertainty.
Matsumoto, Atsushi; Hasegawa, Masaru; Matsui, Keiju
In this paper, a novel position sensorless control method for interior permanent magnet synchronous motors (IPMSMs) that is based on a novel flux model suitable for maximum torque control has been proposed. Maximum torque per ampere (MTPA) control is often utilized for driving IPMSMs with the maximum efficiency. In order to implement this control, generally, the parameters are required to be accurate. However, the inductance varies dramatically because of magnetic saturation, which has been one of the most important problems in recent years. Therefore, the conventional MTPA control method fails to achieve maximum efficiency for IPMSMs because of parameter mismatches. In this paper, first, a novel flux model has been proposed for realizing the position sensorless control of IPMSMs, which is insensitive to Lq. In addition, in this paper, it has been shown that the proposed flux model can approximately estimate the maximum torque control (MTC) frame, which as a new coordinate aligned with the current vector for MTPA control. Next, in this paper, a precise estimation method for the MTC frame has been proposed. By this method, highly accurate maximum torque control can be achieved. A decoupling control algorithm based on the proposed model has also been addressed in this paper. Finally, some experimental results demonstrate the feasibility and effectiveness of the proposed method.
Model predictive torque control with an extended prediction horizon for electrical drive systems
Wang, Fengxiang; Zhang, Zhenbin; Kennel, Ralph; Rodríguez, José
2015-07-01
This paper presents a model predictive torque control method for electrical drive systems. A two-step prediction horizon is achieved by considering the reduction of the torque ripples. The electromagnetic torque and the stator flux error between predicted values and the references, and an over-current protection are considered in the cost function design. The best voltage vector is selected by minimising the value of the cost function, which aims to achieve a low torque ripple in two intervals. The study is carried out experimentally. The results show that the proposed method achieves good performance in both steady and transient states.
Design and control of the phase current of a brushless dc motor to eliminate cogging torque
Jang, G. H.; Lee, C. J.
2006-04-01
This paper presents a design and control method of the phase current to reduce the torque ripple of a brushless dc (BLDC) motor by eliminating cogging torque. The cogging torque is the main source of torque ripple and consequently of speed error, and it is also the excitation source to generate the vibration and noise of a motor. This research proposes a modified current wave form, which is composed of main and auxiliary currents. The former is the conventional current to generate the commutating torque. The latter generates the torque with the same magnitude and opposite sign of the corresponding cogging torque at the given position in order to eliminate the cogging torque. Time-stepping finite element method simulation considering pulse-width-modulation switching method has been performed to verify the effectiveness of the proposed method, and it shows that this proposed method reduces torque ripple by 36%. A digital-signal-processor-based controller is also developed to implement the proposed method, and it shows that this proposed method reduces the speed ripple significantly.
Zhu, Xiaojue; Verzicco, Roberto; Lohse, Detlef
2015-01-01
We present direct numerical simulations of Taylor-Couette flow with grooved walls at a fixed radius ratio $\\eta=r_i/r_o=0.714$ with inner cylinder Reynolds number up to $Re_i=3.76\\times10^4$, corresponding to Taylor number up to $Ta=2.15\\times10^9$. The grooves are axisymmetric V-shaped obstacles attached to the wall with a tip angle of $90^\\circ$. Results are compared with the smooth wall case in order to investigate the effects of grooves on Taylor-Couette flow. We focus on the effective scaling laws for the torque, flow structures, and boundary layers. It is found that, when the groove height is smaller than the boundary layer thickness, the torque is the same as that of the smooth wall cases. With increasing $Ta$, the boundary layer thickness becomes smaller than the groove height. Plumes are ejected from tips of the grooves and a secondary circulation between the latter is formed. This is associated to a sharp increase of the torque and thus the effective scaling law for the torque vs. $Ta$ becomes much ...
Zili Zhang
2014-11-01
Full Text Available Lateral tower vibrations of offshore wind turbines are normally lightly damped, and large amplitude vibrations induced by wind and wave loads in this direction may significantly shorten the fatigue life of the tower. This paper proposes the modeling and control of lateral tower vibrations in offshore wind turbines using active generator torque. To implement the active control algorithm, both the mechanical and power electronic aspects have been taken into consideration. A 13-degrees-of-freedom aeroelastic wind turbine model with generator and pitch controllers is derived using the Euler–Lagrangian approach. The model displays important features of wind turbines, such as mixed moving frame and fixed frame-defined degrees-of-freedom, couplings of the tower-blade-drivetrain vibrations, as well as aerodynamic damping present in different modes of motions. The load transfer mechanisms from the drivetrain and the generator to the nacelle are derived, and the interaction between the generator torque and the lateral tower vibration are presented in a generalized manner. A three-dimensional rotational sampled turbulence field is generated and applied to the rotor, and the tower is excited by a first order wave load in the lateral direction. Next, a simple active control algorithm is proposed based on active generator torques with feedback from the measured lateral tower vibrations. A full-scale power converter configuration with a cascaded loop control structure is also introduced to produce the feedback control torque in real time. Numerical simulations have been carried out using data calibrated to the referential 5-MW NREL (National Renewable Energy Laboratory offshore wind turbine. Cases of drivetrains with a gearbox and direct drive to the generator are considered using the same time series for the wave and turbulence loadings. Results show that by using active generator torque control, lateral tower vibrations can be significantly mitigated for
Self-tuning Torque Control of Induction Motors for High Performance Applications
Rasmussen, Henrik
experiment and theory (simulation) - or nights without sleep. The stator phase voltages are impressed by a standard power device with optical interface to the switch-transistors. Because the stator voltages are not measured directly but only given by the on/off times of the transistors and the DC...... and used together with over-modulation, rated torque at rated speed is shown to be achievable without voltage limitation. On standard motors the field is not a measurable variable and because the whole concept of field oriented control needs precise knowledge of especially the field angle, a good motor...
Reduction of Wind Turbine Torque Fluctuation Using Individual Pitch Control Based on Edgewise Moment
Zhibin Ling
2013-05-01
Full Text Available In order to eliminate the nonuniform force on the wind rotor caused by wind shear, tower shadow and turbulence and smooth the torque fluctuation of the wind turbine and the unbalanced loads on the wind turbine, a new individual pitch control strategy based on edgewise moment using single neuron PID controller is proposed. That is, the presented control strategy directly controls the blade edgewise moment generated by aerodynamic force. At the same time, to simulate the wind turbine loads, a dynamic model of three-bladed upwind horizontal axis wind turbine is built. Thus, the influence rules of the wind turbine torque fluctuation are deduced at length. Finally, to verify the effectiveness of the proposed individual pitch control system with the single neuron PID controller, the 2MW wind turbine generator system is modeled and simulated. The performance of the controller is illustrated its capability of not only reducing the wind turbine fluctuation, but also smoothing the fluctuation of the flapwise moment, the yaw moment and the tilt moment.
Influence of PWM Modes on Commutation Torque Ripples in Sensorless Brushless DC Motor Control System
ZHANGXiang－jun; CHENBo－shi; 等
2001-01-01
This paper introduces four PWM modes used in the sensorless brushless DC motor control system,analyzes their different influences on the commutation torque ripple in detail,and selects the best PWM mode in four given types to reduce commutation torque ripple of Brushless OC( BLDC) motors,Simulation and experimental results show that the selection is correct and practical.
Lu, Tongli; Li, Hongkui; Zhang, Jianwu; Hao, Hongtao
2016-01-01
The objective of this paper is to improve the performance of the synchronizer control strategy by considering the effect of clutch drag torque. The research of synchronization process in wet dual clutch transmission is performed in this paper. The significant effect of clutch drag torque is analyzed by adding a complex clutch drag torque module to synchronizer model. This paper focuses on the development of original estimation method of clutch drag torque. The estimation method offers an effective way to obtain accurate clutch drag torque, and it is applied to develop a new supervisor control strategy. Results have demonstrated that the estimation method has satisfied efficiency and accuracy and the control strategy improves the performance of the synchronizer mechanism significantly.
Kamel, Ouari; Mohand, Ouhrouche; Toufik, Rekioua; Taib, Nabil
2015-01-01
In order to improvement of the performances for wind energy conversions systems (WECS), an advanced control techniques must be used. In this paper, as an alternative to conventional PI-type control methods, a nonlinear predictive control (NPC) approach is developed for DFIG-based wind turbine. To enhance the robustness of the controller, a disturbance observer is designed to estimate the aerodynamic torque which is considered as an unknown perturbation. An explicitly analytical form of the optimal predictive controller is given consequently on-line optimization is not necessary The DFIG is fed through the rotor windings by a back-to-back converter controlled by Pulse Width Modulation (PWM), where the stator winding is directly connected to the grid. The presented simulation results show a good performance in trajectory tracking of the proposed strategy and rejection of disturbances is successfully achieved.
Jing Sun
2015-01-01
Full Text Available The torque coordination control during mode transition is a very important task for hybrid electric vehicle (HEV with a clutch serving as the key enabling actuator element. Poor coordination will deteriorate the drivability of the driver and lead to excessive wearing to the clutch friction plates. In this paper, a novel torque coordination control strategy for a single-shaft parallel hybrid electric vehicle is presented to coordinate the motor torque, engine torque, and clutch torque so that the seamless mode switching can be achieved. Different to the existing model predictive control (MPC methods, only one model predictive controller is needed and the clutch torque is taken as an optimized variable rather than a known parameter. Furthermore, the successful idea of model reference control (MRC is also used for reference to generate the set-point signal required by MPC. The parameter sensitivity is studied for better performance of the proposed model predictive controller. The simulation results validate that the proposed novel torque coordination control strategy has less vehicle jerk, less torque interruption, and smaller clutch frictional losses, compared with the baseline method. In addition, the sensitivity and adaptiveness of the proposed novel torque coordination control strategy are evaluated.
曲瀛; 窦日轩
2001-01-01
This paper introduces a self-adaptive controller based on fuzzy theory which is used as the speed controller in direct torque control system. The controller is made up of traditional PID and fuzzy inference. The parameters of the traditional PID are adjusted by fuzzy inference in real-time so that it can come to self-adaptive controlling of speed.%采用一种基于模糊理论的自适应控制器作为直接转矩控制系统的速度调节器，该控制器由常规PD控制部分和模糊推理两部分组成，通过模糊推理实现常规PID控制器参数的实时优化调整，从而实现速度环的自适应控制，有效地提高了系统响应速度。
Torque Control of Electrorheological Fluidic Actuators for Haptic Vehicular Instrument Controls
Vitrani, Marie-Aude; Nikitczuk, Jason; Morel, Guillaume; Mavroidis, Constantinos
2004-01-01
International audience; Force-feedback mechanisms have been designed to simplify and enhance the human-vehicle interface. The increase in secondary controls within vehicle cockpits has created a desire for a simpler, more efficient human-vehicle interface. By consolidating various controls into a single, haptic feedback control device, information can be transmitted to the operator, without requiring the driver's visual attention. In this work, the experimental closed loop torque control of e...
[An automatic torque control system for a bicycle ergometer equipped with an eddy current brake].
Kikinev, V V
2007-01-01
The main elements of the loading device of a bicycle ergometer, including an eddy current brake and a torque sensor, are described. The automatic torque control system, which includes the loading device, is equipped with a stabilizing feedback controller that optimally approximates the closed-loop transfer function of the target model. The reduced transfer function model of the controller is of the fourth order. A method featuring a modulation-demodulation loop is suggested for implementation of the control system.
Пересада, Сергей Михайлович; Дымко, Сергей Сергеевич; Ковбаса, Сергей Николаевич
2010-01-01
The paper reports a generalized solution of indirect vector control of induction motors with maximum torque per ampere ratio. A novel indirect field-oriented torque tracking controller is designed, which guarantees asymptotic torque and flux tracking with asymptotic field orientation. Results of simulation and experimental tests illustrate important features of the control proposed.
Engine Torque Control of SI Engine using Linear Quadratic Integral Tracking (LQIT Optimal Control
Aris Triwiyatno
2011-11-01
Full Text Available Due to the needs of improving fuel economy and reducing emissions, it is increasingly important to achieve control over robustness behavior and meet performance objectives over the life of the vehicle. This requires the development of high performance and optimal power train controllers. The performance objectives are often conflicting, or at least interrelated. One way to potentially meet these performance requirements is to introduce a method of controlling engine torque of Spark Ignition (SI engine using Linear Quadratic Integral Tracking (LQIT optimal control. The goal is to develop simple algorithms which can control engine torque well, thus providing fuel control more efficient and simultaneously improving engine performance due to the needs of the driver based on throttle opening information. In this case, spark ignition engine with automatic transmission simulation model is used to meet a good performance under this controller design.
Sensorless load torque estimation and passivity based control of buck converter fed DC motor.
Kumar, S Ganesh; Thilagar, S Hosimin
2015-01-01
Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper.
Sensorless Load Torque Estimation and Passivity Based Control of Buck Converter Fed DC Motor
S. Ganesh Kumar
2015-01-01
Full Text Available Passivity based control of DC motor in sensorless configuration is proposed in this paper. Exact tracking error dynamics passive output feedback control is used for stabilizing the speed of Buck converter fed DC motor under various load torques such as constant type, fan type, propeller type, and unknown load torques. Under load conditions, sensorless online algebraic approach is proposed, and it is compared with sensorless reduced order observer approach. The former produces better response in estimating the load torque. Sensitivity analysis is also performed to select the appropriate control variables. Simulation and experimental results fully confirm the superiority of the proposed approach suggested in this paper.
Oliver, Michele; Rogers, Robert; Rickards, Jeremy; Tingley, Maureen; Biden, Edmund
2006-02-22
The purpose of this work was to quantify the effects of joystick stiffness and movement speed on the dynamic torque characteristics of hydraulic-actuation joystick controls, as found in off-road vehicles, as one of the initial steps towards the development of a joystick design protocol. Using a previously developed mathematical model in which a hydraulic-actuation joystick is assumed to rotate about two axes where the rotation origin is a universal joint, the dynamic torque characteristics incurred by an operator were predicted. Utilizing a laboratory mock-up of an excavator cab environment, three actuation torque characteristics (peak torque, angular impulse and deceleration at the hard endpoint) were quantified for nine unskilled joystick operators during the use of a commonly used North American hydraulic-actuation joystick. The six different experimental conditions included combinations of three joystick stiffnesses and two movement speeds. The highest instantaneous input torque over the course of the joystick movement (not including the hard endpoint) was evaluated using the peak torque value. Angular impulse provided an indication of the sustained exposure to force. The third indicator, deceleration at the hard endpoint, was included to provide a description of impact loading on the hand as the joystick came to a sudden stop. The most important result of this work is that the dynamic torque characteristics incurred during hydraulic-actuation joystick use are substantial. While the peak torque values were not very different between the fast and slow motion conditions, the high decelerations even for slow movements observed at maximum excursion of the joystick indicate that the dynamics do matter. On the basis of deceleration at the hard endpoint and peak torque, the joystick movements that require the highest values for a combination of torque variables are the side-to-side ones. This suggests that less stiff balance and return springs should be considered for
Markadeh, Gholamreza Arab [Faculty of Engineering, Shahrekord University, Shahrekord (Iran, Islamic Republic of); Hajian, Masood, E-mail: m.hajian@ec.iut.ac.i [Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Soltani, Jafar; Hosseinia, Saeed [Department of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)
2010-07-15
Field orientation control of induction machine (IM) drives is a well-known strategy which has a fast dynamic response. In this paper, the direct rotor flux field orientation control of speed sensorless IM drive is presented. A two level space vector modulation inverter is employed to generate the command stator voltage. In proposed control scheme, a maximum torque per ampere strategy is achieved using a so-called fast flux search method. Based on this method, for a given load torque and rotor speed, the magnitude of rotor reference flux is adjusted step by step until the effective value of stator current becomes minimized finally. In addition, using the IM fifth order model in the stationary reference frame, a nonlinear rotor flux observer is developed which is also capable of motor resistances and rotor speed simultaneously estimation. Moreover, a useful method is introduced for dc offset compensation which is a major problem of ac drives especially at low speeds. The proposed control idea is experimentally implemented in real time using a CPLD board synchronized with a personal computer. Simulation and experimental results are finally presented to confirm the validity and effectiveness of the proposed method.
Abootorabi Zarchi, H., E-mail: abootorabi9@yahoo.co [Faculty of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Arab Markadeh, Gh.R., E-mail: arab-gh@eng.sku.ac.i [Department of Engineering, Shahrekord University, Shahrekord (Iran, Islamic Republic of); Soltani, J., E-mail: j1234sm@cc.iut.ac.i [Faculty of Electrical and Computer Engineering, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of)
2010-01-15
In this paper, a nonlinear speed tracking controller is introduced for three-phase synchronous reluctance motor (SynRM) on the basis of input-output feedback linearization (IOFL), considering the different control strategies (maximum torque per Ampere, high efficiency and minimum KVA rating for the inverter) related to this motor. The proposed control approach is capable of decoupling control of stator flux and motor generated torque. The validity and effectiveness of the method is verified by simulation and experimental results.
Roithmayr, Carlos M.
1999-01-01
The Attitude Control and Energy Storage Experiment is currently under development for the International Space Station; two counter-rotating flywheels will be levitated with magnetic bearings and placed in vacuum housings. The primary objective of the experiment is to store and discharge energy, in combination with existing batteries, into the electrical power system. The secondary objective is to use the flywheels to exert torque on the Station; a simple torque profile has been designed so that the Station's Control Moment Gyroscopes will be assisted in maintaining torque equilibrium attitude. Two energy storage contingencies could result in the inadvertent application of torque by the flywheels to the Station: an emergency shutdown of one flywheel rotor while the other remains spinning, and energy storage with only one rotor instead of the counterrotating pair. Analysis of these two contingencies shows that attitude control and the microgravity environment will not be adversely affected.
Damping torque analysis of VSC-based system utilizing power synchronization control
Fu, Q.; Du, W. J.; Zheng, K. Y.; Wang, H. F.
2017-05-01
Power synchronization control is a new control strategy of VSC-HVDC for connecting a weak power system. Different from the vector control method, this control method utilizes the internal synchronization mechanism in ac systems, in principle, similar to the operation of a synchronous machine. So that the parameters of controllers in power synchronization control will change the electromechanical oscillation modes and make an impact on the transient stability of power system. This paper present a mathematical model for small-signal stability analysis of VSC station used power synchronization control and analyse the impact of the dynamic interactions by calculating the contribution of the damping torque from the power synchronization control, besides, the parameters of controllers which correspond to damping torque and synchronous torque in the power synchronization control is defined respectively. At the end of the paper, an example power system is presented to demonstrate and validate the theoretical analysis and associated conclusions are made.
Björklund, Martin; Svedmark, Åsa; Srinivasan, Divya; Djupsjöbacka, Mats
2017-01-01
Background Cervical range of motion (ROM) is commonly assessed in clinical practice and research. In a previous study we decomposed active cervical sagittal ROM into contributions from lower and upper levels of the cervical spine and found level- and direction-specific impairments in women with chronic non-specific neck pain. The present study aimed to validate these results and investigate if the specific impairments can be explained by the neutral posture (defining zero flexion/extension) or a movement strategy to avoid large gravitationally induced torques on the cervical spine. Methods Kinematics of the head and thorax was assessed in sitting during maximal sagittal cervical flexion/extension (high torque condition) and maximal protraction (low torque condition) in 120 women with chronic non-specific neck pain and 40 controls. We derived the lower and upper cervical angles, and the head centre of mass (HCM), from a 3-segment kinematic model. Neutral head posture was assessed using a standardized procedure. Findings Previous findings of level- and direction-specific impairments in neck pain were confirmed. Neutral head posture was equal between groups and did not explain the direction-specific impairments. The relative magnitude of group difference in HCM migration did not differ between high and low torques conditions, lending no support for our hypothesis that impairments in sagittal ROM are due to torque avoidance behaviour. Interpretation The direction- and level-specific impairments in cervical sagittal ROM can be generalised to the population of women with non-specific neck pain. Further research is necessary to clarify if torque avoidance behaviour can explain the impairments. PMID:28099504
Design High Efficiency-Minimum Rule Base PID Like Fuzzy Computed Torque Controller
Alireza Khalilian
2014-06-01
Full Text Available The minimum rule base Proportional Integral Derivative (PID Fuzzy Computed Torque Controller is presented in this research. The popularity of PID Fuzzy Computed Torque Controller can be attributed to their robust performance in a wide range of operating conditions and partly to their functional simplicity. The process of setting of PID Fuzzy Computed Torque Controller can be determined as an optimization task. Over the years, use of intelligent strategies for tuning of these controllers has been growing. PID methodology has three inputs and if any input is described with seven linguistic values, and any rule has three conditions we will need 343 rules. It is too much work to write 343 rules. In this research the PID-like fuzzy controller can be constructed as a parallel structure of a PD-like fuzzy controller and a PI controller to have the minimum rule base. However computed torque controller is work based on cancelling decoupling and nonlinear terms of dynamic parameters of each link, this controller is work based on manipulator dynamic model and this technique is highly sensitive to the knowledge of all parameters of nonlinear robot manipulator’s dynamic equation. This research is used to reduce or eliminate the computed torque controller problem based on minimum rule base fuzzy logic theory to control of flexible robot manipulator system and testing of the quality of process control in the simulation environment of MATLAB/SIMULINK Simulator.
Output torque and temperature control technologies for an electrical screw press motor
LI Jun-chao; HUANG Shu-huai; FENG Yi
2008-01-01
The DSC (direct self control) of speed regulation technology was applied to drive a motor running at a certain overloading ratio in intermittent working conditions. To control motor temperatures rising effectively, a finite element method with an iterative approach was applied to simulate real working conditions and analyze the temperature rising of the inner part of the motor. Application of DSC speed regulation realizes the invariable torque output quickly and avoids the peak current at the start state in favor of the motor temperature decreasing. Based on an analysis with the finite limit method, some effective measures were taken to improve the ability of the motor to expel heat. The overload ability of the motor was improved and the stable motor temperature rising was obtained, fulfilling the demands of electrical screw presses.
刘英培; 栗然; 梁海平
2014-01-01
Traditional PI regulator has some defects. Direct torque control (DTC) for permanent magnet synchronous motor (PMSM) based on active-disturbance rejection control (ADRC) optimized by least squares support vector machines (LSSVM) method was proposed in this paper. The speed regulator based on ADRC was designed with the inputs of given speed and real speed and the output of given electromagnet torque. The Gaussian radial basis kernel function was chosen in the model. The realization of the LSSVM regression model embedded in ADRC regulator was analyzed in-depth and detailed, which optimized the ADRC regulator. The ADRC observation precision and dynamic response are improved. The effect of motor parameters and load disturbances on the system is significantly reduced. The anti-interference ability of the system is further improved. Simulation and experiment results have verified the feasibility and effectiveness of this method.%针对传统PI调节器的缺陷，提出一种基于最小二乘支持向量机(least squares support vector machine，LSSVM)优化自抗扰控制器(active-disturbance rejection control， ADRC)的永磁同步电机直接转矩控制方法。以给定转速和实际转速作为输入信号，以给定电磁转矩作为输出信号，设计了 ADRC 速度调节器；在此基础上，在回归模型中选取高斯径向基核函数，深入分析了将LSSVM回归模型有效嵌入ADRC调节器的实现方法，实现对ADRC控制器的优化，以提高 ADRC 观测精度及系统动态响应速度，很大程度上降低了电机参数变化和负载扰动对系统的影响，进一步改善了系统的抗干扰能力。仿真和实验结果验证了该方法的可行性和有效性。
Increasing Elbow Torque Output of Stroke Patients by EMG-Controlled External Torque
2007-11-02
Myoelectric signal processing: optimal estimation applied to electromyography � part 1: derivation of the optimal myprocessor,� IEEE Trans. Biomed...stroke patients. The control signal to the manipulator is the difference between the weighted biceps and triceps EMG, so that the system moves with the...EMG of biceps and triceps. Contrary to the many attempts in the past that used EMG signal for switch control, in the current study, we used EMG
Directly resolving particles in an electric field: local charge, force, torque, and applications
Liu, Qianlong
2011-11-01
Prosperetti's seminal Physalis method for fluid flows with suspended particles is extended to electric fields to directly resolve finite-sized particles and to investigate accurately the mutual fluid-particle, particle-particle, and particle-boundary interactions. The method can be used for uncharged/charged dielectrics, uncharged/charged conductors, conductors with specified voltage, and general weak and strong discontinuous interface conditions. These interface conditions can be in terms of field variable, its gradients, and surface integration which has not been addesed by other numerical methods. In addition, for the first time, we rigorously derive the force and torque on the finite-sized particles resulting from the interactions between harmonics. The method, for the first time, directly resolves the particles with accurate local charge distribution, force, and torque on the particles, making many applications in engineering, mechanics, physics, chemistry, and biology possible, such as heterogeneous materials, microfluidics, electrophotography, electric double layer capacitors, and microstructures of nanodispersions. The efficiency of the method is demonstrated with up to one hundred thousand 3D particles, which suggests that the method can be used for many important engineering applications of broad interest. This research is supported by the Department of Energy under funding for an EFRC (the HeteroFoaM Center), grant no. DE-SC0001061.
Powertrain Torque Control Based on Torque Observer%基于扭矩观测器的动力传动系统扭矩控制
甘海云; 赵长禄; 孙业保; 葛蕴珊; 张付军
2001-01-01
To reduce shock during transmission gear shift, a transmission torque feedback closedloop control system is proposed based on the powertrain system model and a torque observer.The ignition time of engine was delayed to reduce transmission output shaft torque during gear shift. In contrast to traditional control method, the closed-loop control system based on torque observer can obviously reduce the transmission output shaft torque during gear shift. It can be concluded that by way of torque feedback closed-loop control, transmission shift shock can be reduced.%为了减小换档过程的冲击，提出基于动力传动系统模型和扭矩观测器的变速箱扭矩反馈闭环控制系统，在换档过程中推迟发动机点火时刻以降低变速箱输出轴扭矩.与传统控制方法相比，基于扭矩观测器的闭环控制系统能够明显降低换档过程中变速箱输出轴扭矩.实验结果表明，通过扭矩反馈闭环控制方法，可以减小变速箱换档的冲击.
周扬忠; 程明; 熊先云
2015-01-01
逆变器死区、功率管导通压降及开关过渡过程等非线性因素易导致直接转矩控制(direct torque control，DTC)多相永磁同步电机定子电流严重畸变。该文针对六相对称偏置60°定子绕组永磁同步电机提出一种DTC策略。首先，基于零序电流等于零思想进行电压矢量重构，并由此提出理想DTC；其次，基于死区补偿原理对实际电压矢量作用时间进行离散补偿；最后，利用 PI 调节器对电压矢量作用时间进行连续补偿，实现零序电流等于零目的。实验结果表明该文提出的驱动控制系统具有快速的转矩动态响应特性；同时零序电流基本等于零，定子电流总谐波含量较低。%There may be serious distortion in stator currents of multi-phase permanent magnet synchronous motor with direct torque control (DTC) because of the nonlinear factors such as inverter dead-zone, power switch voltage drop and switching transition. A novel DTC was proposed for six-phase symmetric winding phase-shifted by a 60 degree permanent magnet synchronous motor. Firstly, the synthesized voltage vectors were determined to achieve the zero-sequence current, and the ideal DTC strategy was proposed based on the synthesized vectors. Secondly, the factual voltage vector operating time was compensated according to the principle of dead-zone compensation. At last, the voltage vector operating time was regulated continuously by a proportion-integral controller aiming at zero zero-sequence current. The experimental results show that the presented DTC has fast response of torque and the total harmonics is very small due to very lower zero-sequence current.
Robot impedance control and passivity analysis with inner torque and velocity feedback loops
Michele FOCCHI; Gustavo A MEDRANO-CERDA; Thiago BOAVENTURA; Marco FRIGERIO; Claudio SEMINI; Jonas BUCHLI; Darwin G CALDWELL
2016-01-01
Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. In particular, the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops (e.g., a torque loop) as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase (given the constraints to preserve stability) the bandwidth of the torque loop without the need of a complex controller.
A Study of Torque Vectoring and Traction Control for an All-Wheel Drive Electric Vehicle
Maharun Mui’nuddin
2014-07-01
Full Text Available Common vehicle always experience energy loss during cornering manoeuver. Thus, to ensure it did not happened especially at high speed, a study of torque vectoring and traction control need to be made since it can increase the traction control of tyres during cornering at high speed. The study of torque vectoring and traction control for an all-wheel drive electric vehicle was conducted by modelling an all-wheel drive electric vehicle (EV in ADAMS/Car software. In addition, an optimal control algorithm will be developed for best performance to minimize energy losses using MATLAB/Simulink software. Furthermore, to prove the effectiveness of the all-wheel drive electric, the torque and traction control simulation of the all-wheel drive electric vehicle will be compared with uncontrolled electric vehicle model. According to the result, torque vectoring and traction control of in-wheel motor in all wheel drive EV can help to increase the performance of the electric vehicle during cornering manoeuver. In conclusion, this study of torque vectoring and traction control for an all-wheel drive electric vehicle will help researchers to improve the design of the future electric vehicle in term of the vehicle performance during cornering manoeuvre.
Zhao, Z.-G.; Chen, H.-J.; Yang, Y.-Y.; He, L.
2015-09-01
For a hybrid car equipped with dual clutch transmission (DCT), the coordination control problems of clutches and power sources are investigated while taking full advantage of the integrated starter generator motor's fast response speed and high accuracy (speed and torque). First, a dynamic model of the shifting process is established, the vehicle acceleration is quantified according to the intentions of the driver, and the torque transmitted by clutches is calculated based on the designed disengaging principle during the torque phase. Next, a robust H∞ controller is designed to ensure speed synchronisation despite the existence of model uncertainties, measurement noise, and engine torque lag. The engine torque lag and measurement noise are used as external disturbances to initially modify the output torque of the power source. Additionally, during the torque switch phase, the torque of the power sources is smoothly transitioned to the driver's demanded torque. Finally, the torque of the power sources is further distributed based on the optimisation of system efficiency, and the throttle opening of the engine is constrained to avoid sharp torque variations. The simulation results verify that the proposed control strategies effectively address the problem of coordinating control of clutches and power sources, establishing a foundation for the application of DCT in hybrid cars.
Inductance and Active Phase Vector Based Torque Control for Switched Reluctance Motor Drives.
Kalpathi, Ramani Raman
The Switched Reluctance Motor (SRM) drive technology has developed significantly over the last few years. The simplicity in both motor design and power converter requirement along with the availability of high frequency, high power semiconductor switches have made SRMs compete with conventional adjustable speed drive technologies. The subject of winding current control in switched reluctance machines has always been associated with the shaft position information. The use of inductance for direct commutation control is the central subject of this dissertation. In contrast to the conventional methods based on position commutation, new methods of control based on inductance commutation are presented. The object of a commutation algorithm is to switch the currents in the phase coils, in order to provide continuous energy conversion with maximum torque output for a given unit of input current. Since torque production in a SRM is based on the concept of variable reluctance, it makes more sense to observe the instantaneous phase inductance or reluctance instead of estimating the rotor position. The inductance sensors observe the machine parameters and provide sufficient information on the electrical characteristics of the coils. This control strategy avoids the inductance to position transformation blocks conventionally used in SRM control systems. In a typical SRM, the phase coils have a nonlinear behavior of inductance due to effects of current saturation. Also the parameters of one phase coil differ from those of the other due to manufacturing tolerances or due to bearing wear. In such cases, the algorithms written during the stage of manufacturing may not be valid after parameter changes. Optimizing torque production in the event of phase asymmetry and saturation is developed in this research. Indirect sensors connected to the active phase coil of the SRM are based on sensing the flux level in the active coil. New commutation algorithms based on flux sensing concepts
Nikitczuk, Jason; Weinberg, Brian; Mavroidis, Constantinos
2007-04-01
In this paper we present control algorithms for novel electro-rheological fluid based resistive torque generation elements that will be used to drive the joint of a new type of portable and controllable active knee rehabilitation orthotic device (AKROD) for iso-inertial, isokinetic, and isometric exercising as well as gait retraining. The AKROD is composed of straps and rigid components for attachment to the leg, with a central hinge mechanism where a gear system is connected. The key features of AKROD include: a compact, lightweight design with highly tunable torque capabilities through a variable damper component, full portability with on-board power, control circuitry, and sensors (encoder and torque), and real-time capabilities for closed loop computer control for optimizing gait retraining. The variable damper component is achieved through an electro-rheological fluid (ERF) element that connects to the output of the gear system. Using the electrically controlled rheological properties of ERFs, compact brakes capable of supplying high resistive and controllable torques are developed. In this project, a prototype for the AKROD has been developed and tested. The AKROD's ERF resistive actuator was tested in laboratory experiments using a custom-made ERF testing apparatus (ETA). ETA provides a computer-controlled environment to test ERF brakes and actuators in various conditions and scenarios including emulating the interaction between human muscles involved with the knee and the AKROD's ERF actuators/brakes. The AKROD's ERF resistive actuator was tested in closed loop torque control experiments. A hybrid (non-linear, adaptive) proportional-integral (PI) torque controller was implemented to achieve this goal.
GU Yanchun; YIN Chengliang; ZHANG Jianwu
2007-01-01
In parallel hybrid electrical vehicle (PHEV) equipped with automatic mechanical transmission (AMT), the driving smoothness and the clutch abrasion are the primary considerations for powertrain control during gearshift and clutch operation. To improve these performance indexes of PHEV, a coordinated control system is proposed through the analyzing of HEV powertrain dynamic characteristics. Using the method of minimum principle, the input torque of transmission is optimized to improve the driving sinoothness of vehicle. Using the methods of fuzzy logic and fuzzy-PID, the engaging speed of clutch and the throttle opening of engine are manipulated to ensure the smoothness of clutch engagement and reduce the abrasion of clutch friction plates. The motor provides the difference between the required input torque of transmission and the torque transmitted through clutch plates. Results of simulation and experiments show that the proposed control strategy performs better than the contrastive control system, the smoothness of driving and the abrasion of clutch can be improved simultaneously.
孙振兴; 张兴华
2012-01-01
提出了一种定子磁链滑模观测器,该观测器以定子电流和磁链作为状态变量,利用电流观测误差时定子磁链观测值进行校正,采用李雅普诺夫理论证明了观测器是渐近收敛的.设计了基于定子磁链滑模观测器的感应电机无速度传感器的直接转矩控制系统,将磁链估计值用于对转速进行实时估计.实验结果表明,采用滑模观测器的感应电机无速度传感器直接转矩控制系统,具有转矩动态响应快,转速控制精度高和调速范围宽的特点.%In this paper, a novel sliding-mode observer for stator flux estimation is proposed. This observer employs stator currents and flux as the state variables, and uses the error of the stator current estimation to adjust the flux observer. The convergence of the observer is proved by Lyapunov's stability theory. Then, a speed sensor-less direct torque control system of induction motor drives based on the sliding-mode flux observer is designed, which uses the slip frequency method to calculate the speed on real time. The experimental results show that the proposed the control scheme possesses the features of fast torque response, accurate speed tracking and wide range of speed.
张凤阁; 朱连成; 金石; 于思洋
2016-01-01
Based on the principle of wind power generator maximum power point tracking ( MPPT ), combined with the special structure of brushless doubly-fed machine,which does not have brushes and slip rings, and allowing for the adopted double stator magnetic field modulation method,so that the capacity of required converters is smaller,then a novel scheme of direct torque control and fuzzy control inn brushless doubly-fed generator system is proposed,which the control winding is opened and fed with dual two-level converters. The principles of each part,i. e. the maximum power point tracking,the open winding strategy,the direct torque control,and the fuzzy control are all explained in detail. Then the MPPT of brushless doubly-fed wind power generators with the open winding direct torque fuzzy control strategy model,i. e. the control winding is fed with dual two-level SVPWM converters,is built and researched using the Matlab/Simulink software. The excellent performances are obtained by the simulation results. Finally, the correctness and feasibility of the proposed strategy are confirmed by the semi-physical simulation experimental platform,which can provide a good reference to further develop the semi-physical simulation experimental platform and the related control strategies.%基于风力发电机最大功率点跟踪原理，结合无刷双馈电机无电刷和集电环的特殊结构及采用双定子磁场调制使得所需变流器容量更小的特点，提出了一种由双两电平变流器拓扑构造三电平馈电的开绕组策略，阐述了无刷双馈风力发电机最大功率点跟踪、开绕组策略及直接转矩控制、模糊控制等各部分工作原理，进而利用Matlab/Simulink仿真软件，搭建了无刷双馈风力发电机控制绕组采用双两电平SVPWM变流器馈电实现最大功率点跟踪的开绕组直接转矩模糊控制模型，并进行了详细的性能仿真，最后，通过无刷双馈电机半实物仿真实验平台
Direct Numerical Simulations of Local and Global Torque in Taylor-Couette Flow up to Re=30.000
Brauckmann, Hannes
2015-01-01
The torque in turbulent Taylor-Couette flows for shear Reynolds numbers Re_S up to 3x10^4 at various mean rotations is studied by means of direct numerical simulations for a radius ratio of \\eta=0.71. Convergence of simulations is tested using three criteria of which the agreement of dissipation values estimated from the torque and from the volume dissipation rate turns out to be most demanding. We evaluate the influence of Taylor vortex heights on the torque for a stationary outer cylinder and select a value of the aspect ratio of \\Gamma=2, close to the torque maximum. The connection between the torque and the transverse current J^\\omega of azimuthal motion which can be computed from the velocity field enables us to investigate the local transport resulting in the torque. The typical spatial distribution of the individual convective and viscous contributions to the local current is analysed for a turbulent flow case. To characterise the turbulent statistics of the transport, PDF's of local current fluctuatio...
Torque vector control using neural network controller for synchronous reluctance motor
Feng, X. [Teco-Westinghouse Motor Co, R and D Center, Round Rock, TX (United States); Belmans, R.; Hameyer, K. [Katholieke Universiteit Leuven, Dic. ELEN, Dept. ESAT, Leuven-Heverlee (Belgium)
2000-08-01
This paper presents the torque vector control technique using a neural network controller for a synchronous reluctance motor. As the artificial neural network controller has the advantages of faster execution speed, harmonic ripple immunity and fault tolerance compared to a DSP-based controller, different multi-layer neural network controllers are designed and trained to produce a correct target vector when presented with the corresponding input vector. The trained result and calculated flops show that although the designed three layer controller with tansig, purelin and hard limit functions has more processing layers, the neuron number of each layer is less than that of other kinds of neural network controller, the requiring less flops and yielding faster execution and response. (orig.)
Resistance Torque Based Variable Duty-Cycle Control Method for a Stage II Compressor
Zhong, Meipeng; Zheng, Shuiying
2017-07-01
The resistance torque of a piston stage II compressor generates strenuous fluctuations in a rotational period, and this can lead to negative influences on the working performance of the compressor. To restrain the strenuous fluctuations in the piston stage II compressor, a variable duty-cycle control method based on the resistance torque is proposed. A dynamic model of a stage II compressor is set up, and the resistance torque and other characteristic parameters are acquired as the control targets. Then, a variable duty-cycle control method is applied to track the resistance torque, thereby improving the working performance of the compressor. Simulated results show that the compressor, driven by the proposed method, requires lower current, while the rotating speed and the output torque remain comparable to the traditional variable-frequency control methods. A variable duty-cycle control system is developed, and the experimental results prove that the proposed method can help reduce the specific power, input power, and working noise of the compressor to 0.97 kW·m-3·min-1, 0.09 kW and 3.10 dB, respectively, under the same conditions of discharge pressure of 2.00 MPa and a discharge volume of 0.095 m3/min. The proposed variable duty-cycle control method tracks the resistance torque dynamically, and improves the working performance of a Stage II Compressor. The proposed variable duty-cycle control method can be applied to other compressors, and can provide theoretical guidance for the compressor.
Frequency control of a spin-torque oscillator using magnetostrictive anisotropy
Park, Min Gyu Albert; Lee, Seok-Hee, E-mail: bgpark@kaist.ac.kr, E-mail: shlee@kaist.edu [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Baek, Seung-heon Chris [Department of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of); Park, Byong-Guk, E-mail: bgpark@kaist.ac.kr, E-mail: shlee@kaist.edu [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)
2016-01-11
We report the working principle of a spin-torque oscillator, of which the frequency is efficiently controlled by manipulating the magnetostrictive anisotropy. To justify the scheme, we simulate a conventional magnetic-tunnel junction-based oscillator which is fabricated on a piezoelectric material. By applying mechanical stress to a free layer using a piezoelectric material, the oscillation frequency can be controlled to ensure a broad tuning range without a significant reduction of the dynamic resistance variation. Such controllability, which appears in the absence of an external magnetic field, will not only enable the integration of spin-torque oscillators and conventional complimentary metal-oxide semiconductor technology but will also broaden the applicability of spin-torque oscillators.
Johnson, Reva E; Koerding, Konrad P; Hargrove, Levi J; Sensinger, Jonathon W
2016-08-25
In this paper we asked the question: if we artificially raise the variability of torque control signals to match that of EMG, do subjects make similar errors and have similar uncertainty about their movements? We answered this question using two experiments in which subjects used three different control signals: torque, torque+noise, and EMG. First, we measured error on a simple target-hitting task in which subjects received visual feedback only at the end of their movements. We found that even when the signal-to-noise ratio was equal across EMG and torque+noise control signals, EMG resulted in larger errors. Second, we quantified uncertainty by measuring the just-noticeable difference of a visual perturbation. We found that for equal errors, EMG resulted in higher movement uncertainty than both torque and torque+noise. The differences suggest that performance and confidence are influenced by more than just the noisiness of the control signal, and suggest that other factors, such as the user's ability to incorporate feedback and develop accurate internal models, also have significant impacts on the performance and confidence of a person's actions. We theorize that users have difficulty distinguishing between random and systematic errors for EMG control, and future work should examine in more detail the types of errors made with EMG control.
Selami KESLER
2009-01-01
Full Text Available The power flow of the rotor circuit is controlled by different methods in induction machines used for producing high torque in applications involved great power and constant output power with constant frequency in wind turbines. The voltage with slip frequency can be applied on rotor windings to produce controlled high torque and obtain optimal power factor and speed control. In this study, firstly, the dynamic effects of the voltage applying on rotor windings through the rings in slip-ring induction machines are researched and undesirable aspects of the method are exposed with simulations supported by experiments. Afterwards, a fuzzy logic based inverter model on rotor side is proposed with a view to improving the dynamic effects, controlling high torque producing and adjusting machine speed in instantaneous forced conditions. For the simulation model of the system in which the stator side is directly connected to the grid in steady state operation, a C/C++ algorithm is developed and the results obtained for different load conditions are discussed.
The PHD: A Planar, Harmonic Drive Robot for Joint Torque Control
1990-07-01
Technical Report AI-TR 1072, August, 1989. [5] Eppinger, S.D. and Seering, W.P., "On Dynamic Models of Robot Force Control ", MIT Artificial... Robot Force Control ", Proceedings of the IEEE Conference on Robotics and Automation, April, 1985, Vol. 1, pp. 262- 268. 80 Appendix A: Torque Sensor
Nor Faezah Alias
2013-12-01
Full Text Available Three-level Neutral Point Clamped (NPC inverter allows the configuration of switching devices to operate at high voltage and produce lower current/voltage harmonics. It is known that, DTC of induction machine which employs hysteresis controller has major drawbacks namely larger torque ripple and variable switching frequency. This paper aims to propose a suitable voltage vector selection to provide better torque regulation and lower switching frequency by employing DTC with 3-level NPC multilevel inverter. A simple switching strategy was formulated using 7-level torque hysteresis and 2-level flux hysteresis controllers to give more options in selecting an appropriate voltage vector, inherently, according the motor operation conditions. The improvements offered were verified through simulations.
Tracking control of time-varying knee exoskeleton disturbed by interaction torque.
Li, Zhan; Ma, Wenhao; Yin, Ziguang; Guo, Hongliang
2017-08-16
Knee exoskeletons have been increasingly applied as assistive devices to help lower-extremity impaired people to make their knee joints move through providing external movement compensation. Tracking control of knee exoskeletons guided by human intentions often encounters time-varying (time-dependent) issues and the disturbance interaction torque, which may dramatically put an influence up on their dynamic behaviors. Inertial and viscous parameters of knee exoskeletons can be estimated to be time-varying due to unexpected mechanical vibrations and contact interactions. Moreover, the interaction torque produced from knee joint of wearers has an evident disturbance effect on regular motions of knee exoskeleton. All of these points can increase difficultly of accurate control of knee exoskeletons to follow desired joint angle trajectories. This paper proposes a novel control strategy for controlling knee exoskeleton with time-varying inertial and viscous coefficients disturbed by interaction torque. Such designed controller is able to make the tracking error of joint angle of knee exoskeletons exponentially converge to zero. Meanwhile, the proposed approach is robust to guarantee the tracking error bounded when the interaction torque exists. Illustrative simulation and experiment results are presented to show efficiency of the proposed controller. Additionally, comparisons with gradient dynamic (GD) approach and other methods are also presented to demonstrate efficiency and superiority of the proposed control strategy for tracking joint angle of knee exoskeleton. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
VIKAS KUMAR; PRERNA GAUR; A P MITTAL
2017-03-01
Among the numerous direct torque control techniques, the finite-state predictive torque control (FS-PTC) has emerged as a powerful alternative as it offers the fast dynamic response and the flexibility to optimize multiple objectives simultaneously. However, the implementation of FS-PTC for multiple objectives optimization requires the optimization of a single objective function, which is constructed using weighting factors asa linear combination of individual objective functions. Traditionally, the weighting factors are determined through a non-trivial process, which is a complex and time-consuming task. In an effort to avoid the timeconsuming task of weighting factor selection, this paper aims at replacing the weighting factor calculation with a systematic fuzzy multiple-criteria decision making in which the individual objective functions may have equalor varying degrees of importance. As a result the weighting factor calculation can be completely avoided. The simulation and experimental tests are conducted on a 2.2 kW induction motor drive to validate the proposed approach. The result outcomes are compared with the conventional predictive torque control (PTC) using weighting factors on the same experimental platform.
Durability investigation on torque control of a magneto-rheological brake: experimental work
Kim, Wan Ho; Park, Jhin Ha; Kim, Gi-Woo; Shin, Cheol Soo; Choi, Seung-Bok
2017-03-01
This study experimentally investigates the torque control durability of a disc brake featuring a magneto-rheological (MR) fluid. An appropriate size of MR disc brake is designed based on a mathematical model, and a prototype is manufactured. A small-scale laboratory-scale test bed is then developed using a DC motor, in-line torque sensor, and the MR brake. S45C and S20C steels are inserted into a tapered hole on the surface of the brake disc. After 105 cycles of operation in shear mode, the wear properties of the MR brake are characterized by average surface roughness measurements, scanning electron microscope images, and energy dispersive x-ray spectra. The torque control performances before and after the operation cycles are examined using open-loop control and closed-loop proportional-integral-derivative control. As expected, the control performance degraded after 105 cycles of operation in the open-loop case, but not in the closed-loop case. This aspect is demonstrated by the sinusoidal torque-tacking control performance before and after the operation cycles.
Variable frequency inverter for ac induction motors with torque, speed and braking control
Nola, F. J. (Inventor)
1975-01-01
A variable frequency inverter was designed for driving an ac induction motor which varies the frequency and voltage to the motor windings in response to varying torque requirements for the motor so that the applied voltage amplitude and frequency are of optimal value for any motor load and speed requirement. The slip frequency of the motor is caused to vary proportionally to the torque and feedback is provided so that the most efficient operating voltage is applied to the motor. Winding current surge is limited and a controlled negative slip causes motor braking and return of load energy to a dc power source.
Mohd Sabirin Rahmat
2013-06-01
Full Text Available This paper presents a detailed derivation of a permanent magnet synchronous motor, which may be used as the electric power train for the simulation of a hybrid electric vehicle. A torque tracking control of the permanent magnet synchronous motor is developed by using an adaptive proportional-integral-derivative controller. Several tests such as step function, saw tooth function, sine wave function and square wave function were used in order to examine the performance of the proposed control structure. The effectiveness of the proposed controller was verified and compared with the same system under a PID controller and the desired control. The result of the observations shows that the proposed control structure proves to be effective in tracking the desired torque with a good response. The findings of this study will be considered in the design, optimisation and experimentation of series hybrid electric vehicle.
Diepeveen, N.F.B.; Jarquin-Laguna, A.
2014-01-01
In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near maximu
Diepeveen, N.F.B.; Jarquin-Laguna, A.
2014-01-01
In this paper the results are presented of experiments to prove an innovative concept for passive torque control of variable speed wind turbines using fluid power technology. It is demonstrated that by correctly configuring the hydraulic drive train, the wind turbine rotor operates at or near maximu
HuangMiao-hua; JinGuo-dong
2003-01-01
The Hierarchical Structure Fuzzy Logic Control(HSFLC) strategies of torque distribute for Parallel Hybrid Electric Vehicle (PHEV) in the mocle of operation of the vehicle i. e. , acceleration, cruise, deceleration etc. have been studied. Using secondly developed the hybrid vehicle simulation tool ADVISOR, the dynamic model of PHEV has been set up by MATLAB/SIMULINK. The engine, motor as well as the battery characteristics have been studied. Simulation results show that the proposed hierarchical structured fuzzy logic control strategy is effective over the entire operating range of the vehicle in terms of fuel economy. Based on the analyses of the simulation results and driver's experiences, a fuzzy controller is designed and developed to control the torque distribution. The controller is evaluated via hardware-in-the-loop simulator (HILS). The results show that controller verify its value.
Torque blending and wheel slip control in EVs with in-wheel motors
de Castro, Ricardo; Araújo, Rui E.; Tanelli, Mara; Savaresi, Sergio M.; Freitas, Diamantino
2012-01-01
Among the many opportunities offered by electric vehicles (EVs), the design of power trains based on in-wheel electric motors represents, from the vehicle dynamics point of view, a very attractive prospect, mainly due to the torque-vectoring capabilities. However, this distributed propulsion also poses some practical challenges, owing to the constraints arising from motor installation in a confined space, to the increased unsprung mass weight and to the integration of the electric motor with the friction brakes. This last issue is the main theme of this work, which, in particular, focuses on the design of the anti-lock braking system (ABS). The proposed structure for the ABS is composed of a tyre slip controller, a wheel torque allocator and a braking supervisor. To address the slip regulation problem, an adaptive controller is devised, offering robustness to uncertainties in the tyre-road friction and featuring a gain-scheduling mechanism based on the vehicle velocity. Further, an optimisation framework is employed in the torque allocator to determine the optimal split between electric and friction brake torque based on energy performance metrics, actuator constraints and different actuators bandwidth. Finally, based on the EV working condition, the priorities of this allocation scheme are adapted by the braking supervisor unit. Simulation results obtained with the CarSim vehicle model, demonstrate the effectiveness of the overall approach.
Torque control of synchronous and induction generators for variable speed operation of wind turbines
Carlson, Ola; Ulen, E. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering
1996-12-01
The aim of this paper is to investigate variable speed electrical systems. Synchronous generators with diode rectifiers and line-commutated thyristor converters are compared with induction generators with force commutated transistor converters and scalar control. The system characteristics are examined regarding possible speed of response (bandwidth) of the torque control, including the sensitivity to disturbances for the drive train and also the possibility to get damping of the drive train resonance. Analyses, simulations and laboratory tests with a 40 kW machine set-up have been performed. The investigation shows that the system with synchronous generator is well suited for wind power applications. A rapid standard DC-current regulator is included in the torque control and can be used for damping of the resonance. The torque control has a bandwidth up to about 3 Hz and the DC-voltage controller up to about 1 Hz. The system with induction generator with scalar control (no transformations) is more difficult to control. A linear approach is only possible up to about 1.5 Hz. In this region it turns out that the behaviour can be visualized as an added inertia on the generator side that can be rather big. 4 refs, 9 figs
The robust application of computed torque control to manipulators subject to saturation
Lokshin, Anatole; Lee, Sukhan
1988-01-01
A technique is presented which allows use of an exact linearization (EL) control for robot manipulators for those cases when actuator saturation cannot be ignored. A modification of a nonlinear dynamic compensation technique that has been successfully used in the feedback amplifiers is applied to a case of a nonredundant manipulator. Computer simulation for a two-link planar robot arm illustrates the advantages of the modified computed torque technique compared to the traditional linear full state control.
基于直接转矩控制的电动叉车驱动系统理论研究%THE TESEACH BASED ON DIRECT TORQUE CONTROL SYSTEM FOR ELECTRIC FORKLIFT
袁雪松; 贺爱香
2013-01-01
Electrical Eenergy, as a kind of energy source which applies to engineering vehicles, has an outstanding advantage of zero emission, and no pollution, with an extremely broad developing prospect. Driving motor and its controlingcontrolling system are the hard-core of the whole system of electric vehicle. Asynchronous motor, with its distinctive dcharacteristics of small size, simple maintenance, and high reliability, has been widely apply to Eelectric engineering vehicles.This thesis We studieds the exchange AC control system of Eelectric forklift. According to the performance index needed byof the Eelectric forklift, the thesiswe analyzedses the advantage and disadvantage of the drive system of Electric vehicle and advantage and disadvantage of all kinds of motor, discusseds the development and current situations of AC adjustable speed control technology, and further analyzeds the basic principles, structures and algorithms of DTC by using the analysing methodology of space voltage vector.%电能作为能源应用于工程车辆，具有零排放无污染的突出优点，开发前景十分广阔。驱动电机及其控制系统是电动汽车动力系统中的核心部分，异步电机以其体积小，维护简单、可靠性高等优点在电动工程车辆中得到最广泛的应用。主要研究电动叉车交流控制系统，根据电动叉车的性能指标，分析电动叉车驱动系统和各种驱动电机的优缺点，讨论了交流调速控制技术的发展和现状，采用空间电压矢量分析方法分析了直接转矩控制的基本原理、结构和算法。
Zhou, Ping; Suresh, Nina L.; Zev Rymer, William
2011-06-01
The objective of this study was to determine whether a novel technique using high density surface electromyogram (EMG) recordings can be used to detect the directional dependence of muscle activity in a multifunctional muscle, the first dorsal interosseous (FDI). We used surface EMG recordings with a two-dimensional electrode array to search for inhomogeneous FDI activation patterns with changing torque direction at the metacarpophalangeal joint, the locus of action of the FDI muscle. The interference EMG distribution across the whole FDI muscle was recorded during isometric contraction at the same force magnitude in five different directions in the index finger abduction-flexion plane. The electrode array EMG activity was characterized by contour plots, interpolating the EMG amplitude between electrode sites. Across all subjects the amplitude of the flexion EMG was consistently lower than that of the abduction EMG at the given force. Pattern recognition methods were used to discriminate the isometric muscle contraction tasks with a linear discriminant analysis classifier, based on the extraction of two different feature sets of the surface EMG signal: the time domain (TD) feature set and a combination of autoregressive coefficients and the root mean square amplitude (AR+RMS) as a feature set. We found that high accuracies were obtained in the classification of different directions of the FDI muscle isometric contraction. With a monopolar electrode configuration, the average overall classification accuracy from nine subjects was 94.1 ± 2.3% for the TD feature set and 95.8 ± 1.5% for the AR+RMS feature set. Spatial filtering of the signal with bipolar electrode configuration improved the average overall classification accuracy to 96.7 ± 2.7% for the TD feature set and 98.1 ± 1.6% for the AR+RMS feature set. The distinct EMG contour plots and the high classification accuracies obtained from this study confirm distinct interference EMG pattern distributions as a
Sensorless torque control scheme of induction motor for hybrid electric vehicle
Yan LIU; Cheng SHAO
2007-01-01
In this paper,the sensorless torque robust tracking problem of the induction motor for hybrid electric vehicle(HEV)applications is addressed.Because motor parameter variations in HEV applications are larger than in industrial drive system,the conventional field-oriented control(FOC)provides poor performance.Therefore,a new robust PI-based extension of the FOC controller and a speed-flux observer based on sliding mode and Lyapunov theory are developed in order to Improve the overall performance.Simulation results show that the proposed sensorless torque control scheme is robust with respect to motor parameter variations and loading disturbances.In addition,the operating flux of the motor is chosen optimally to minimize the consumption of electric energy,which results in a significant reduction in energy losses shown by simulations.
Electric-field control of spin-orbit torque in a magnetically doped topological insulator
Fan, Yabin; Kou, Xufeng; Upadhyaya, Pramey; Shao, Qiming; Pan, Lei; Lang, Murong; Che, Xiaoyu; Tang, Jianshi; Montazeri, Mohammad; Murata, Koichi; Chang, Li-Te; Akyol, Mustafa; Yu, Guoqiang; Nie, Tianxiao; Wong, Kin L.; Liu, Jun; Wang, Yong; Tserkovnyak, Yaroslav; Wang, Kang L.
2016-04-01
Electric-field manipulation of magnetic order has proved of both fundamental and technological importance in spintronic devices. So far, electric-field control of ferromagnetism, magnetization and magnetic anisotropy has been explored in various magnetic materials, but the efficient electric-field control of spin-orbit torque (SOT) still remains elusive. Here, we report the effective electric-field control of a giant SOT in a Cr-doped topological insulator (TI) thin film using a top-gate field-effect transistor structure. The SOT strength can be modulated by a factor of four within the accessible gate voltage range, and it shows strong correlation with the spin-polarized surface current in the film. Furthermore, we demonstrate the magnetization switching by scanning gate voltage with constant current and in-plane magnetic field applied in the film. The effective electric-field control of SOT and the giant spin-torque efficiency in Cr-doped TI may lead to the development of energy-efficient gate-controlled spin-torque devices compatible with modern field-effect semiconductor technologies.
Guo Hong; Xu Jinquan
2015-01-01
This paper proposes a novel fault tolerant control with torque limitation based on the fault mode for the ten-phase permanent magnet synchronous motor (PMSM) under various open-circuit and short-circuit fault conditions, which includes the optimal torque control and the torque limitation control based on the fault mode. The optimal torque control is adopted to guarantee the ripple-free electromagnetic torque operation for the ten-phase motor system under the post-fault condition. Furthermore, we systematically analyze the load capacity of the ten-phase motor system under different fault modes. And a torque limitation control approach based on the fault mode is proposed, which was not available earlier. This approach is able to ensure the safety operation of the faulted motor system in long operating time without causing the overheat fault. The simulation result confirms that the proposed fault tolerant control for the ten-phase motor system is able to guarantee the ripple-free electromagnetic torque and the safety operation in long operating time under the normal and fault conditions.
Guo Hong
2015-10-01
Full Text Available This paper proposes a novel fault tolerant control with torque limitation based on the fault mode for the ten-phase permanent magnet synchronous motor (PMSM under various open-circuit and short-circuit fault conditions, which includes the optimal torque control and the torque limitation control based on the fault mode. The optimal torque control is adopted to guarantee the ripple-free electromagnetic torque operation for the ten-phase motor system under the post-fault condition. Furthermore, we systematically analyze the load capacity of the ten-phase motor system under different fault modes. And a torque limitation control approach based on the fault mode is proposed, which was not available earlier. This approach is able to ensure the safety operation of the faulted motor system in long operating time without causing the overheat fault. The simulation result confirms that the proposed fault tolerant control for the ten-phase motor system is able to guarantee the ripple-free electromagnetic torque and the safety operation in long operating time under the normal and fault conditions.
Jinhyun Park
2015-08-01
Full Text Available The in-wheel electric vehicle is expected to be a popular next-generation vehicle because an in-wheel system can simplify the powertrain and improve driving performance. In addition, it also has an advantage in that it maximizes driving efficiency through independent torque control considering the motor efficiency. However, there is an instability problem if only the driving torque is controlled in consideration of only the motor efficiency. In this paper, integrated torque distribution strategies are proposed to overcome these problems. The control algorithm consists of various strategies for optimizing driving efficiency, satisfying driver demands, and considering tire slip and vehicle cornering. Fuzzy logic is used to determine the appropriate timing of intervention for each distribution strategy. A performance simulator for in-wheel electric vehicles was developed by using MATLAB/Simulink and CarSim to validate the control strategies. From simulation results under complex driving conditions, the proposed algorithm was verified to improve both the driving stability and fuel economy of the in-wheel vehicle.
Mengnan Liu
2016-01-01
Full Text Available In order to improve the electrical conversion efficiency of an electric tractor motor, a load torque based control strategy (LTCS is designed in this paper by using a particle swarm optimization algorithm (PSO. By mathematically modeling electric-mechanical performance and theoretical energy waste of the electric motor, as well as the transmission characteristics of the drivetrain, the objective function, control relationship, and analytical platform are established. Torque and rotation speed of the motor’s output shaft are defined as manipulated variables. LTCS searches the working points corresponding to the best energy conversion efficiency via PSO to control the running status of the electric motor and uses logic and fuzzy rules to fit the search initialization for load torque fluctuation. After using different plowing forces to imitate all the common tillage forces, the simulation of traction experiment is conducted, which proves that LTCS can make the tractor use electrical power efficiently and maintain agricultural applicability on farmland conditions. It provides a novel method of fabricating a more efficient electric motor used in the traction of an off-road vehicle.
Dual Control of Giant Field-like Spin Torque in Spin Filter Tunnel Junctions
Tang, Y.-H.; Chu, F.-C.; Kioussis, Nicholas
2015-06-01
We predict a giant field-like spin torque, , in spin-filter (SF) barrier tunnel junctions in sharp contrast to existing junctions based on nonmagnetic passive barriers. We demonstrate that has linear bias behavior, is independent of the SF thickness, and has odd parity with respect to the SF’s exchange splitting. Thus, it can be selectively controlled via external bias or external magnetic field which gives rise to sign reversal of via magnetic field switching. The underlying mechanism is the interlayer exchange coupling between the noncollinear magnetizations of the SF and free ferromagnetic electrode via the nonmagnetic insulating (I) spacer giving rise to giant spin-dependent reflection at the SF/I interface. These findings suggest that the proposed field-like-spin-torque MRAM may provide promising dual functionalities for both ‘reading’ and ‘writing’ processes which require lower critical current densities and faster writing and reading speeds.
Electric Control of Dirac Quasiparticles by Spin-Orbit Torque in an Antiferromagnet
Šmejkal, L.; Železný, J.; Sinova, J.; Jungwirth, T.
2017-03-01
Spin orbitronics and Dirac quasiparticles are two fields of condensed matter physics initiated independently about a decade ago. Here we predict that Dirac quasiparticles can be controlled by the spin-orbit torque reorientation of the Néel vector in an antiferromagnet. Using CuMnAs as an example, we formulate symmetry criteria allowing for the coexistence of topological Dirac quasiparticles and Néel spin-orbit torques. We identify the nonsymmorphic crystal symmetry protection of Dirac band crossings whose on and off switching is mediated by the Néel vector reorientation. We predict that this concept verified by minimal model and density functional calculations in the CuMnAs semimetal antiferromagnet can lead to a topological metal-insulator transition driven by the Néel vector and to the topological anisotropic magnetoresistance.
Electric-field control of spin-orbit torque in magnetically doped topological insulators
Fan, Yabin; Shao, Qiming; Kou, Xufeng; Upadhyaya, Pramey; Wang, Kang
Recent advances of spin-orbit torques (SOTs) generated by topological insulators (TIs) have drawn increasing interest to the spin-momentum locking feature of TIs' surface states, which can potentially provide a very efficient means to generate SOTs for spintronic applications. In this presentation, we will show the magnetization switching through current-induced giant SOT in both TI/Cr-doped TI bilayer and uniformly Cr-doped TI films In particular, we show that the current-induced SOT has significant contribution from the spin-momentum locked surface states of TIs. We find that the spin torque efficiency is in general three orders of magnitude larger than those reported in heavy metal/ferromagnetic heterostructures. In the second part, we will present the electric-field control of the giant SOT in magnetically doped TIs, which suggests promising gate-controlled spin-torque device applications. The giant SOT and efficient current-induced magnetization switching exhibited by the magnetic TIs may lead to innovative spintronic applications such as ultralow power dissipation memory and logic devices. We acknowledge the supports from DARPA, FAME, SHINES and ARO programs.
AN ALGORITHM OF ADAPTIVE TORQUE CONTROL IN INJECTOR INTERNAL COMBUSTION ENGINE
D. N. Gerasimov
2015-07-01
Full Text Available Subject of Research. Internal combustion engine as a plant is a highly nonlinear complex system that works mostly in dynamic regimes in the presence of noise and disturbances. A number of engine characteristics and parameters is not known or known approximately due to the complex structure and multimode operating of the engine. In this regard the problem of torque control is not trivial and motivates the use of modern techniques of control theory that give the possibility to overcome the mentioned problems. As a consequence, a relatively simple algorithm of adaptive torque control of injector engine is proposed in the paper. Method. Proposed method is based on nonlinear dynamic model with parametric and functional uncertainties (static characteristics which are suppressed by means of adaptive control algorithm with single adjustable parameter. The algorithm is presented by proportional control law with adjustable feedback gain and provides the exponential convergence of the control error to the neighborhood of zero equilibrium. It is shown that the radius of the neighborhood can be arbitrary reduced by the change of controller design parameters. Main Results. A dynamical nonlinear model of the engine has been designed for the purpose of control synthesis and simulation of the closed-loop system. The parameters and static functions of the model are identified with the use of data aquired during Federal Test Procedure (USA of Chevrolet Tahoe vehicle with eight cylinders 5,7L engine. The algorithm of adaptive torque control is designed, and the properties of the closed-loop system are analyzed with the use of Lyapunov functions approach. The closed-loop system operating is verified by means of simulation in the MatLab/Simulink environment. Simulation results show that the controller provides the boundedness of all signals and convergence of the control error to the neighborhood of zero equilibrium despite significant variations of engine speed. The
A moving control volume approach to computing hydrodynamic forces and torques on immersed bodies
Nangia, Nishant; Johansen, Hans; Patankar, Neelesh A.; Bhalla, Amneet Pal Singh
2017-10-01
We present a moving control volume (CV) approach to computing hydrodynamic forces and torques on complex geometries. The method requires surface and volumetric integrals over a simple and regular Cartesian box that moves with an arbitrary velocity to enclose the body at all times. The moving box is aligned with Cartesian grid faces, which makes the integral evaluation straightforward in an immersed boundary (IB) framework. Discontinuous and noisy derivatives of velocity and pressure at the fluid-structure interface are avoided and far-field (smooth) velocity and pressure information is used. We re-visit the approach to compute hydrodynamic forces and torques through force/torque balance equations in a Lagrangian frame that some of us took in a prior work (Bhalla et al., 2013 [13]). We prove the equivalence of the two approaches for IB methods, thanks to the use of Peskin's delta functions. Both approaches are able to suppress spurious force oscillations and are in excellent agreement, as expected theoretically. Test cases ranging from Stokes to high Reynolds number regimes are considered. We discuss regridding issues for the moving CV method in an adaptive mesh refinement (AMR) context. The proposed moving CV method is not limited to a specific IB method and can also be used, for example, with embedded boundary methods.
Eduardo Espíndola-López
2016-09-01
Full Text Available A new Fourier Series Learning Controller (FSLC for velocity control on a Permanent Magnet Synchronous Motor (PMSM is proposed and implemented. An analysis of the error convergence for the FSLC is presented, and the update law for the Fourier series coefficients is specified. The field-oriented control method is used as a basic element to implement three different controllers for a PMSM. The performance of the FSLC is compared with two control methods, a classical PI (Proportional Integral controller and an artificial neural network controller. The periodic nature of torque ripple in PMSMs is considered as a periodic disturbance, which must be compensated by the controller. With the FSLC implementation, a substantial reduction of the velocity ripple is obtained. Furthermore, a higher speed of learning is achieved with the FSLC in comparison with the artificial neural network.
骆光照; 张围围; 杨南方; 马鹏; 刘卫国
2012-01-01
A flux linkage compensation field oriented control (FOC) method was proposed to suppress the speed and torque ripples of a hrusbless wound-fleld synchronous motor in its starting process. The starting process was analyzed and the model of wound-field synchronous electric machine was established. The change of field current of the electric machine was described mathematically for simplified exciter and rotate rectifier. Based on the traditional field control, the flux linkage compensation was introduced in d-axis current to counteract the flux ripple. Some simulation and preliminary experiments were implemented. The results show that the proposed method is feasible and effective.
Zhang, Rui-Qin; Qi, Fei; Hermann, Klaus; Van Hove, Michel A
2016-01-01
Torque is ubiquitous in many molecular systems, including collisions, chemical reactions, vibrations, electronic excitations and especially rotor molecules. We present a straightforward theoretical method based on forces acting on atoms and obtained from atomistic quantum mechanics calculations, to quickly and qualitatively determine whether a molecule or sub-unit thereof has a tendency to rotation and, if so, around which axis and in which sense: clockwise or counterclockwise. The method also indicates which atoms, if any, are predominant in causing the rotation. Our computational approach can in general efficiently provide insights into the rotational ability of many molecules and help to theoretically screen or modify them in advance of experiments or before analyzing their rotational behavior in more detail with more extensive computations guided by the results from the torque approach. As an example, we demonstrate the effectiveness of the approach using a specific light-driven molecular rotary motor whi...
Computed torque control of an under-actuated service robot platform modeled by natural coordinates
Zelei, Ambrus; Kovács, László L.; Stépán, Gábor
2011-05-01
The paper investigates the motion planning of a suspended service robot platform equipped with ducted fan actuators. The platform consists of an RRT robot and a cable suspended swinging actuator that form a subsequent parallel kinematic chain and it is equipped with ducted fan actuators. In spite of the complementary ducted fan actuators, the system is under-actuated. The method of computed torques is applied to control the motion of the robot. The under-actuated systems have less control inputs than degrees of freedom. We assume that the investigated under-actuated system has desired outputs of the same number as inputs. In spite of the fact that the inverse dynamical calculation leads to the solution of a system of differential-algebraic equations (DAE), the desired control inputs can be determined uniquely by the method of computed torques. We use natural (Cartesian) coordinates to describe the configuration of the robot, while a set of algebraic equations represents the geometric constraints. In this modeling approach the mathematical model of the dynamical system itself is also a DAE. The paper discusses the inverse dynamics problem of the complex hybrid robotic system. The results include the desired actuator forces as well as the nominal coordinates corresponding to the desired motion of the carried payload. The method of computed torque control with a PD controller is applied to under-actuated systems described by natural coordinates, while the inverse dynamics is solved via the backward Euler discretization of the DAE system for which a general formalism is proposed. The results are compared with the closed form results obtained by simplified models of the system. Numerical simulation and experiments demonstrate the applicability of the presented concepts.
Applied Joint-Space Torque and Stiffness Control of Tendon-Driven Fingers
Abdallah, Muhammad E.; Platt, Robert, Jr.; Wampler, Charles W.; Hargrave, Brian
2010-01-01
Existing tendon-driven fingers have applied force control through independent tension controllers on each tendon, i.e. in the tendon-space. The coupled kinematics of the tendons, however, cause such controllers to exhibit a transient coupling in their response. This problem can be resolved by alternatively framing the controllers in the joint-space of the manipulator. This work presents a joint-space torque control law that demonstrates both a decoupled and significantly faster response than an equivalent tendon-space formulation. The law also demonstrates greater speed and robustness than comparable PI controllers. In addition, a tension distribution algorithm is presented here to allocate forces from the joints to the tendons. It allocates the tensions so that they satisfy both an upper and lower bound, and it does so without requiring linear programming or open-ended iterations. The control law and tension distribution algorithm are implemented on the robotic hand of Robonaut-2.
Lei Wang
2014-01-01
Full Text Available Offshore floating wind turbine (OFWT has been a challenging research spot because of the high-quality wind power and complex load environment. This paper focuses on the research of variable torque control of offshore wind turbine on Spar floating platform. The control objective in below-rated wind speed region is to optimize the output power by tracking the optimal tip-speed ratio and ideal power curve. Aiming at the external disturbances and nonlinear uncertain dynamic systems of OFWT because of the proximity to load centers and strong wave coupling, this paper proposes an advanced radial basis function (RBF neural network approach for torque control of OFWT system at speeds lower than rated wind speed. The robust RBF neural network weight adaptive rules are acquired based on the Lyapunov stability analysis. The proposed control approach is tested and compared with the NREL baseline controller using the “NREL offshore 5 MW wind turbine” model mounted on a Spar floating platform run on FAST and Matlab/Simulink, operating in the below-rated wind speed condition. The simulation results show a better performance in tracking the optimal output power curve, therefore, completing the maximum wind energy utilization.
Computed torque control of a free-flying cooperat ing-arm robot
Koningstein, Ross; Ullman, Marc; Cannon, Robert H., Jr.
1989-01-01
The unified approach to solving free-floating space robot manipulator end-point control problems is presented using a control formulation based on an extension of computed torque. Once the desired end-point accelerations have been specified, the kinematic equations are used with momentum conservation equations to solve for the joint accelerations in any of the robot's possible configurations: fixed base or free-flying with open/closed chain grasp. The joint accelerations can then be used to calculate the arm control torques and internal forces using a recursive order N algorithm. Initial experimental verification of these techniques has been performed using a laboratory model of a two-armed space robot. This fully autonomous spacecraft system experiences the drag-free, zero G characteristics of space in two dimensions through the use of an air cushion support system. Results of these initial experiments are included which validate the correctness of the proposed methodology. The further problem of control in the large where not only the manipulator tip positions but the entire system consisting of base and arms must be controlled is also presented. The availability of a physical testbed has brought a keener insight into the subtleties of the problem at hand.
Flicker Mitigation Strategy for a Doubly Fed Induction Generator by Torque Control
Zhang, Yunqian; Hu, Weihao; Chen, Zhe
2014-01-01
induction generator is presented to investigate the flicker mitigation. Taking advantage of the large inertia of the wind turbine rotor, a generator torque control (GTC) strategy is proposed, so that the power oscillation is stored as the kinetic energy of the wind turbine rotor, thus the flicker emission...... could be reduced. The GTC scheme is proposed and designed according to the generator rotational speed. The simulations are performed on the national renewable energy laboratory 1.5 MW upwind reference wind turbine model. Simulation results show that damping the generator active power by GTC...
Frequency Control Support of a Doubly-Fed Induction Generator Based on the Torque Limit
Kang, Moses; Kim, Keonhui; Muljadi, Eduard; Park, Jung-Wook; Kang, Yong Cheol
2016-11-01
This paper proposes a torque limit-based inertial control scheme of a doubly-fed induction generator (DFIG) that supports the frequency control of a power system. If a frequency deviation occurs, the proposed scheme aims to release a large amount of kinetic energy (KE) stored in the rotating masses of a DFIG to raise the frequency nadir (FN). Upon detecting the event, the scheme instantly increases its output to the torque limit and then reduces the output with the rotor speed so that it converges to the stable operating range. To restore the rotor speed while causing a small second frequency dip (SFD), after the rotor speed converges the power reference is reduced by a small amount and maintained until it meets the reference for maximum power point tracking control. The test results demonstrate that the scheme can improve the FN and maximum rate of change of frequency while causing a small SFD in any wind conditions and in a power system that has a high penetration of wind power, and thus the scheme helps maintain the required level of system reliability. The scheme releases the KE from 2.9 times to 3.7 times the Hydro-Quebec requirement depending on the power reference.
Min, Kyuengbo; Shin, Duk; Lee, Jongho; Kakei, Shinji
2013-01-01
Muscle activity is the final signal for motion control from the brain. Based on this biological characteristic, Electromyogram (EMG) signals have been applied to various systems that interface human with external environments such as external devices. In order to use EMG signals as input control signal for this kind of system, the current EMG driven torque estimation models generally employ the mathematical model that estimates the nonlinear transformation function between the input signal and the output torque. However, these models need to estimate too many parameters and this process cause its estimation versatility in various conditions to be poor. Moreover, as these models are designed to estimate the joint torque, the input EMG signals are tuned out of consideration for the physiological synergetic contributions of multiple muscles for motion control. To overcome these problems of the current models, we proposed a new tuning model based on the synergy control mechanism between multiple muscles in the cortico-spinal tract. With this synergetic tuning model, the estimated contribution of multiple muscles for the motion control is applied to tune the EMG signals. Thus, this cortico-spinal control mechanism-based process improves the precision of torque estimation. This system is basically a forward dynamics model that transforms EMG signals into the joint torque. It should be emphasized that this forward dynamics model uses a musculo-skeletal model as a constraint. The musculo-skeletal model is designed with precise musculo-skeletal data, such as origins and insertions of individual muscles or maximum muscle force. Compared with the mathematical model, the proposed model can be a versatile model for the torque estimation in the various conditions and estimates the torque with improved accuracy. In this paper, we also show some preliminary experimental results for the discussion about the proposed model.
Aho, Jacob; Fleming, Paul; Pao, Lucy Y.
2016-08-01
As wind energy generation becomes more prevalent in some regions, there is increased demand for wind power plants to provide ancillary services, which are essential for grid reliability. This paper compares two different wind turbine control methodologies to provide active power control (APC) ancillary services, which include derating or curtailing power generation, providing automatic generation control (AGC), and providing primary frequency control (PFC). The torque APC controller provides all power control through the power electronics whereas the pitch APC controller uses the blade pitch actuators as the primary means of power control. These controllers are simulated under various wind conditions with different derating set points and AGC participation levels. The metrics used to compare their performance are the damage equivalent loads (DELs) induced on the structural components and AGC performance metrics, which are used to determine the payments for AGC services by system operators in the United States. The simulation results show that derating the turbine reduces structural loads for both control methods, with the APC pitch control providing larger reductions in DELs, lower AGC performance scores, and higher root-mean-square pitch rates. Providing AGC increases the structural loads when compared to only derating the turbine, but even the AGC DELs are generally lower than those of the baseline control system. The torque APC control methodology also allows for more sustained PFC responses under certain derating conditions.
Observer-Based Nonlinear Control of A Torque Motor with Perturbation Estimation
J Chen; E Prempain; Q H Wu
2006-01-01
This paper presents an observer-based nonlinear control method that was developed and implemented to provide accurate tracking control of a limited angle torque motor following a 50Hz reference waveform. The method is based on a robust nonlinear observer, which is used to estimate system states and perturbations and then employ input-output feedback linearization to compensate for the system nonlinearities and uncertainties. The estimation of system states and perturbations allows input-output linearization of the nonlinear system without an accurate mathematical model of nominal plant. The simulation results show that the observer-based nonlinear control method is superior in comparison with the conventional model-based state feedback linearizing controller.
Torque control in lingual orthodontics with lever arm mechanics: a case report.
Aravind, M; Shivaprakash, G; Ramesh, G C
2013-01-01
The aim of this report is to illustrate treatment mechanics for torque control in lingual mechanotherapy using a lever arm and transpalatal arch (TPA) tab system during en masse retraction of anterior teeth. An 18-year-old female with bimaxillary dentoalveolar proclination with crowding was treated with a lever arm-TPA tab system. The retraction tabs bent into the TPA placed across the maxillary second molars were used as anchorage. The retraction force on the maxillary anterior teeth was applied using lever arm hooks soldered between the lateral incisors and canines on a lingual mushroom archwire. By applying a retraction force to the lever arm hooks, the maxillary anterior teeth experienced greater palatal root movement as compared to the conventional retraction forces applied at the crown level. The tabs, placed high in the TPA, produced a distal tipping moment on the maxillary second molars, reinforcing their anchorage. The retraction force applied to the long lever arm hooks from the TPA tabs at the level of center of resistance (CRes) of anterior and posterior teeth is advantageous mainly in two aspects. First, it reinforces the anchorage, and second, it favors the palatal root movement of anterior teeth, thus obtaining better control over the torque during en masse retraction.
Spin Orbit Torque in Ferromagnetic Semiconductors
Li, Hang
2016-06-21
Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read\\' and `write\\' in memory devices can be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall
Simon N. Pearson
2016-06-01
Full Text Available Grinding is a key physical element in America’s Cup sailing. This study aimed to describe kinematics and muscle activation patterns in relation to torque applied in forward and backward grinding. Ten male America’s Cup sailors (33.6 ± 5.7 years, 97.9 ± 13.4 kg, 186.6 ± 7.4 cm completed forward and backward grinding on a customised grinding ergometer. In forward grinding peak torque (77 Nm occurred at 95° (0° = crank vertically up on the downward section of the rotation at the end of shoulder flexion and elbow extension. Backward grinding torque peaked at 35° (69 Nm following the pull action (shoulder extension, elbow flexion across the top of the rotation. During forward grinding, relatively high levels of torque (>50 Nm were maintained through the majority (72% of the cycle, compared to 47% for backward grinding, with sections of low torque corresponding with low numbers of active muscles. Variation in torque was negatively associated with forward grinding performance (r = −0.60; 90% CI −0.88 to −0.02, but positively associated with backward performance (r = 0.48; CI = −0.15 to 0.83. Magnitude and distribution of torque generation differed according to grinding direction and presents an argument for divergent training methods to improve forward and backward grinding performance.
Nikitczuk, Jason; Weinberg, Brian; Mavroidis, Constantinos
2006-03-01
In this paper we present the design and control algorithms for novel electro-rheological fluid based torque generation elements that will be used to drive the joint of a new type of portable and controllable Active Knee Rehabilitation Orthotic Device (AKROD) for gait retraining in stroke patients. The AKROD is composed of straps and rigid components for attachment to the leg, with a central hinge mechanism where a gear system is connected. The key features of AKROD include: a compact, lightweight design with highly tunable torque capabilities through a variable damper component, full portability with on board power, control circuitry, and sensors (encoder and torque), and real-time capabilities for closed loop computer control for optimizing gait retraining. The variable damper component is achieved through an electro-rheological fluid (ERF) element that connects to the output of the gear system. Using the electrically controlled rheological properties of ERFs, compact brakes capable of supplying high resistive and controllable torques, are developed. A preliminary prototype for AKROD v.2 has been developed and tested in our laboratory. AKROD's v.2 ERF resistive actuator was tested in laboratory experiments using our custom made ERF Testing Apparatus (ETA). ETA provides a computer controlled environment to test ERF brakes and actuators in various conditions and scenarios including emulating the interaction between human muscles involved with the knee and AKROD's ERF actuators / brakes. In our preliminary results, AKROD's ERF resistive actuator was tested in closed loop torque control experiments. A hybrid (non-linear, adaptive) Proportional-Integral (PI) torque controller was implemented to achieve this goal.
Zhiguo Zhao
2014-01-01
Full Text Available Based on the independently developed five-speed dry dual clutch transmission (DDCT, the paper proposes the torque coordinating control strategy between engine and two clutches, which obtains engine speed and clutch transferred torque in the shifting process, adequately reflecting the driver intention and improving the shifting quality. Five-degree-of-freedom (DOF shifting dynamics model of DDCT with single intermediate shaft is firstly established according to its physical characteristics. Then the quantitative control objectives of the shifting process are presented. The fuzzy decision of shifting time and the model-based torque coordinating control strategy are proposed and also verified by simulating under different driving intentions in up-/downshifting processes with the DCT model established on the MATLAB/Simulink. Simulation results validate that the shifting control algorithm proposed in this paper can not only meet the shifting quality requirements, but also adapt to the various shifting intentions, having a strong robustness.
Suffridge, Calvin B; Hartwell, Gary R; Walker, Thomas L
2003-05-01
This study determined if the cleaning efficiency of nickel-titanium rotary files in an endodontic electric handpiece using a no-torque control setting was superior to that obtained when using the torque-control feature. Fifty extracted human anterior teeth with straight canals were divided into two groups of 20 and two control groups of 5. Canals were instrumented with GT and .04 ProFile nickel-titanium files until a size 35 advanced to working length. Samples were sectioned and the apical 6 mm of the canal was photographed (x20) and projected onto a 3- x 4-foot grid with squares measuring 0.5 inches each. Total debris was the percentage of the number of squares containing debris versus the total number of squares. The teeth in the torque-controlled group showed an average of 24.99% debris versus 15.55% for the teeth in the no-torque group. The difference was not statistically significant; therefore, no difference can be said to exist between the two torque settings in terms of cleaning efficiency.
Adaptive critic learning techniques for engine torque and air-fuel ratio control.
Liu, Derong; Javaherian, Hossein; Kovalenko, Olesia; Huang, Ting
2008-08-01
A new approach for engine calibration and control is proposed. In this paper, we present our research results on the implementation of adaptive critic designs for self-learning control of automotive engines. A class of adaptive critic designs that can be classified as (model-free) action-dependent heuristic dynamic programming is used in this research project. The goals of the present learning control design for automotive engines include improved performance, reduced emissions, and maintained optimum performance under various operating conditions. Using the data from a test vehicle with a V8 engine, we developed a neural network model of the engine and neural network controllers based on the idea of approximate dynamic programming to achieve optimal control. We have developed and simulated self-learning neural network controllers for both engine torque (TRQ) and exhaust air-fuel ratio (AFR) control. The goal of TRQ control and AFR control is to track the commanded values. For both control problems, excellent neural network controller transient performance has been achieved.
Guo Hong
2015-04-01
Full Text Available Improving fault tolerant performance of permanent magnet synchronous motor has always been the central issue of the electrically supplied actuator for aerospace application. In this paper, a novel fault tolerant permanent magnet synchronous motor is proposed, which is characterized by two stators and two rotors on the same shaft with a circumferential displacement of mechanical angle of 4.5°. It helps to reduce the cogging torque. Each segment of the stator and the rotor can be considered as an 8-pole/10-slot five-phase permanent magnet synchronous motor with concentrated, single-layer and alternate teeth wound winding, which enhance the fault isolation capacity of the motor. Furthermore, the motor has high phase inductance to restrain the short-circuit current. In addition, an improved optimal torque control strategy is proposed to make the motor work well under the open-circuit fault and short-circuit fault conditions. Simulation and experiment results show that the proposed fault tolerant motor system has excellent fault tolerant capacity, which is able to operate continuously under the third open-circuit fault and second short-circuit fault condition without system performance degradation, which was not available earlier.
Zhu, Z.Q.; Chen, Y. S.; Howe, D.
2002-01-01
The airgap flux density distribution, flux density loci in the stator core, and the associated iron loss in two topologies of brushless AC motor, having a surface-mounted magnet rotor and an interior-mounted magnet rotor, respectively, are investigated when operated under maximum torque per ampere control in the constant torque mode and maximum power control in the flux-weakening mode. It is shown that whilst the interior magnet topology is known to be eminently suitable for flux-weakening op...
Shepherd, Max K; Rouse, Elliott J
2016-08-01
Individuals with post-stroke hemiparesis often have difficulty standing out of a chair. One way to potentially improve sit-to-stand is to provide knee extension assistance using a powered knee exoskeleton. An exoskeleton providing unilateral, partial assistance during sit-to-stand would need to be torque-controllable. There are no knee exoskeletons on the market suitable for conducting experiments assisting stroke patients with sit-to-stand, so to enable such experiments a research device was developed. The purpose of this report is to present the design of a novel knee exoskeleton actuator that uses a fiberglass leaf spring in series to improve torque-controllability, and present a characterization of the actuator performance. The actuator is capable of the required torque and speed for sit-to-stand, has high bandwidth (25 Hz), low output impedance at low frequencies (sit-to-stand.
Xu, Xiangbo; Chen, Shao; Liu, Jinhao
2017-04-04
Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB) systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. Firstly, the dynamics of a four radial degrees of freedom AMB system is described, and the AMB model can be described in terms of the translational and rotational motions, respectively. Next, a closed-loop generalized notch filter is utilized to identify the synchronous displacement resulting from the rotor imbalance, and a feed-forward compensation of the synchronous force and torque related to the AMB displacement stiffness is formulated by using the identified synchronous displacement. Then, a plug-in repetitive controller is designed to track the synchronous feed-forward compensation adaptively and to suppress the harmonic vibrations due to the sensor runout. Finally, the proposed control method is verified by simulations and experiments. The control algorithm is insensitive to the parameter variations of the power amplifiers and can precisely suppress the harmonic force and torque. Its practicality stems from its low computational load.
Xiangbo Xu
2017-04-01
Full Text Available Harmonic force and torque, which are caused by rotor imbalance and sensor runout, are the dominant disturbances in active magnetic bearing (AMB systems. To eliminate the harmonic force and torque, a novel control method based on repetitive control and notch filters is proposed. Firstly, the dynamics of a four radial degrees of freedom AMB system is described, and the AMB model can be described in terms of the translational and rotational motions, respectively. Next, a closed-loop generalized notch filter is utilized to identify the synchronous displacement resulting from the rotor imbalance, and a feed-forward compensation of the synchronous force and torque related to the AMB displacement stiffness is formulated by using the identified synchronous displacement. Then, a plug-in repetitive controller is designed to track the synchronous feed-forward compensation adaptively and to suppress the harmonic vibrations due to the sensor runout. Finally, the proposed control method is verified by simulations and experiments. The control algorithm is insensitive to the parameter variations of the power amplifiers and can precisely suppress the harmonic force and torque. Its practicality stems from its low computational load.
Abolfazl Halvaei Niasar
2016-01-01
Full Text Available Nowadays, due to excellent advantages of permanent magnet brushless (PMBL motors such as high efficiency and high torque/power density, they are used in many industrial and variable-speed electrical drives applications. If the fabricated PMBL motor has neither ideal sinusoidal nor ideal trapezoidal back-EMF voltages, it is named nonideal (or nonsinusoidal PMBL motor. Employing conventional control strategies of PMSMs and BLDCMs lowers the efficiency and leads to unwanted torque ripple, vibration, and acoustic noises. Moreover, in many applications to reduce the cost and enhance the reliability of drive, sensorless control techniques are used. This paper proposes a novel sensorless control for a nonsinusoidal PMBL motor with minimum torque ripple. To develop smooth torque, the selected torque harmonic elimination strategy is employed. Furthermore, to estimate the rotor position and speed, a novel full-order sliding mode observer is designed. Proposed observer estimates the position and speed of motor from standstill to final speed. The proposed observer is robust to uncertainty of harmonic contents in phase back-EMF voltage and able to run the motor from standstill with closed-loop control scheme. The capabilities of torque ripple minimization and sensorless strategies are demonstrated with some simulations.
Zhao, Z. G.; Chen, H. J.; Zhen, Z. X.; Yang, Y. Y.
2014-06-01
As for the self-developed six-speed dry dual-clutch transmission (DCT), the optimal torque-coordinated control strategy between engine and dual clutches is proposed to resolve the problem of launching with twin clutches simultaneously involved based on the minimum value principle. Focusing on the sliding friction phase of the launching process, dynamics equations of dry DCT with two intermediate shafts are firstly established, and then the optimal transmitting torque variation rate and the driven plate's rotating speed of dual clutches are deduced by using the minimum value principle, in which the jerk intensity and friction work are taken as the performance indexes, and the terminal constraints of state variables are determined according to the driver's launching intention. Besides, the separating conditions of non-target gear clutch and the torque distributing relations of twin clutches are derived from the launching control targets that guarantee the approximately equal friction extent of two clutches and no power cycle. After the synchronisation of driving and driven plates of on-coming clutch, the output torque of engine is smoothly switched to the driver's demand level. Furthermore, launching the simulation model of the dry DCT vehicle is set up on the Matlab/Simulink platform. Simulation results indicate that the proposed launching control strategy not only can effectively reflect the driver's intention and extend the life span of twin clutches, but also obtain an excellent launching quality. Finally, the torque control laws of two clutches obtained through the simulation are transformed into clutch position control laws for the future realisation in the real car, and the closed-loop position controls of twin clutches in the launching process are conducted on the test bench with two sets of clutch actuator, obtaining preferable tracking effects.
Pace, D. C.; Collins, C. S.; Crowley, B.; Grierson, B. A.; Heidbrink, W. W.; Pawley, C.; Rauch, J.; Scoville, J. T.; Van Zeeland, M. A.; Zhu, Y. B.; The DIII-D Team
2017-01-01
A first-ever demonstration of controlling power and torque injection through time evolution of neutral beam energy has been achieved in recent experiments at the DIII-D tokamak (Luxon 2002 Nucl. Fusion 42 614). Pre-programmed waveforms for the neutral beam energy produce power and torque inputs that can be separately and continuously controlled. Previously, these inputs were tailored using on/off modulation of neutral beams resulting in large perturbations (e.g. power swings of over 1 MW). The new method includes, importantly for experiments, the ability to maintain a fixed injected power while varying the torque. In another case, different beam energy waveforms (in the same plasma conditions) produce significant changes in the observed spectrum of beam ion-driven instabilities. Measurements of beam ion loss show that one energy waveform results in the complete avoidance of coherent losses due to Alfvénic instabilities. This new method of neutral beam operation is intended for further application in a variety of DIII-D experiments including those concerned with high-performance steady state scenarios, fast particle effects, and transport in the low torque regime. Developing this capability would provide similar benefits and improved plasma control for other magnetic confinement fusion facilities.
Torque exerted on the side of crustal blocks controls the kinematics of Ethiopian Rift
Muluneh, Ameha A.; Kidane, Tesfaye; Cuffaro, Marco; Doglioni, Carlo
2016-04-01
Plate tectonic stress at active plate boundary can arises from 1) a torque applied on the side of lithospheric blocks and 2) a torque at the base of the lithosphere due to the flow of the underlying mantle. In this paper we use a simple force balance analysis to compare side and basal shear stresses and their contribution in driving kinematics and deformation in the Ethiopian Rift (ER), in the northern part of the East African Rift System (EARS). Assuming the constraints of the ER given by the dimension of the lithospheric blocks, the strain rate, the viscosity of the low velocity zone (LVZ) and the depth of the brittle-ductile transition zone, the lateral torque is several orders of magnitude higher than the basal torque. The minor contribution of basal torque might be due to low viscosity in the LVZ. Both Africa and Somalia plates are moving to the "west" relative to the mantle and there are not slabs that can justify this pull and consequent motion. Therefore, we invoke that westerly oriented tidal torque on Africa and Somalia plates in providing the necessary side torque in the region. This plate motion predicts significant sinistral transtension along the ER and rift parallel strike-slip faulting similar to the estimated angular velocity vector for tectonic blocks and GPS observations. Vertical axis block rotations are observed in areas where the lithospheric mantle is removed and strain is widely distributed.
National Aeronautics and Space Administration — TRS Technologies, Virginia Tech., and MTech, Inc. propose to develop high torque (>1.5 kg-cm), lightweight (< 250 g), low power (< 2 watts), high precision...
National Aeronautics and Space Administration — TRS Technologies proposes novel single crystal piezomotors for large torque, high precision, and cryogenic actuation with capability of position set-hold with...
Light wire auxiliaries with pre-adjusted edgewise appliance to control individual incisor torque
Sharanya Sabrish
2015-01-01
The use of light wire auxiliaries have definite advantages and hence should be a part of our armamentarium to handle such cases. Light wire auxiliaries offer us a biomechanically superior and economical alternative to apply torque forces on incisors.
王喜莲; 许振亮; 王翠
2015-01-01
Torque-ripple of switched reluctance motor ( SRM ) is inevitable for its double saliency con-struction and switch power supply. To minimize the torque-ripple, according to unsaturation inductance-angle characteristics curve of the SRM, a torque distribution synthesis control method based on exponen-tial function to decrease SRM torque ripple and copper losses was proposed. The reference torque was di-rectly translated into the reference current using the torque formula and lookup table method to avoid the torque measure. Meanwhile, the proposed method was compared with the traditional sinusoidal torque distribution control method. The results show its superiority of the operational efficiency. The optimal bal-ance scheme employing weighting function of torque ripple minimization and operational efficiency was proposed by setting torque ripple minimization as the major optimal object, reducing the stator winding commutation current as a secondary condition. The control system simulation model of a 3kw 12/8 poles switched reluctance motor was built to verify the validity of the proposed method.%针对开关磁阻电机( switched reluctance motor, SRM)的双凸极结构导致其运行时产生很强的转矩脉动现象,根据SRM非饱和特性下电感与角度关系曲线,提出一种基于指数函数的SRM转矩脉动与铜耗最小化转矩分配综合控制方法,该方法综合转矩计算式和查表法将参考转矩直接转化为参考电流,避免了对转矩的测量。与正弦转矩分配控制进行比较分析,在电机工作效率方面验证了该控制系统性能的优越性；提出将转矩脉动抑制作为主要优化对象,抑制定子绕组换相电流作为次级条件,利用加权函数实现转矩脉动抑制与运行效率的优化平衡方案。以一台3 kw的12/8极开关磁阻电机为控制对象,建立控制系统仿真模型,验证了方案的有效性。
Robin N Mathew
2016-01-01
Conclusion: Forces that produce a translation in LaO tends to produce uncontrolled tipping in lingual technique. To obtain adequate torque control in lingual technique, a combination of the reduction in horizontal retraction forces, increased lingual root torque application, and increase in vertical intrusive forces is desirable.
Zhu, X.; Ostilla-Monico, Rodolfo; Verzicco, R.; Lohse, D.
2016-01-01
We present direct numerical simulations of Taylor–Couette flow with grooved walls at a fixed radius ratio ${\\it\\eta}=r_{i}/r_{o}=0.714$η=ri/ro=0.714 with inner cylinder Reynolds number up to $Re_{i}=3.76\\times 10^{4}$Rei=3.76×104, corresponding to Taylor number up to $Ta=2.15\\times 10^{9}$Ta=2.15×10
Park, Jihyuk; Kim, Ji-Chul; Kim, Kyung-Soo; Kim, Soohyun
2016-12-01
A tendon-driven robot joint that has a low inertia compared with a conventional drive system is proposed. The robot joint displaces the drive system toward the robot base, and it is driven by twisted string actuators (TSAs), which are a substitute for the conventional heavy drive system. The design of the proposed robot joint is based on an antagonistic scheme that is actuated by two motors. The torques from the motors are transmitted to the robot joint through the TSAs. Based on the geometric analysis of TSAs, strategies for position and torque control are proposed for an antagonistic robot joint driven by TSAs. To verify the proposed control strategies, several control experiments are conducted using a developed prototype of a robot joint.
Krishnan, Hariharan; Reyhanoglu, Mahmut; McClamroch, Harris
1994-06-01
The attitude stabilization problem of a rigid spacecraft using control torques supplied by gas jet actuators about only two of its principal axes is considered. If the uncontrolled principal axis of the spacecraft is not an axis of symmetry, then the complete spacecraft dynamics are small time locally controllable. However, the spacecraft cannot be asymptotically stabilized to any equilibrium attitude using time-invariant continuous feedback. A discontinuous stabilizing feedback control strategy is constructed which stabilizes the spacecraft to any equilibrium attitude. If the uncontrolled principal axis of the spacecraft is an axis of symmetry, the complete spacecraft dynamics are not even assessible. However, the spacecraft dynamics are strongly accessible and small time locally controllable in a reduced sense. The reduced spacecraft dynamics cannot be asymptotically stabilized to any equilibrium attitude using time-invariant continuous feedback, but again a discontinuous stabilizing feedback control strategy is constructed. In both cases, the discontinuous feedback controllers are constructed by switching between several feedback functions which are selected to accomplish a sequence of spacecraft maneuvers. The results of the paper show that although standard nonlinear control techniques are not applicable, it is possible to construct a nonlinear discontinuous control law based on the dynamics of the particular physical system.
Yu, Jue; Zhuang, Jian; Yu, Dehong
2015-01-01
This paper concerns a state feedback integral control using a Lyapunov function approach for a rotary direct drive servo valve (RDDV) while considering parameter uncertainties. Modeling of this RDDV servovalve reveals that its mechanical performance is deeply influenced by friction torques and flow torques; however, these torques are uncertain and mutable due to the nature of fluid flow. To eliminate load resistance and to achieve satisfactory position responses, this paper develops a state feedback control that integrates an integral action and a Lyapunov function. The integral action is introduced to address the nonzero steady-state error; in particular, the Lyapunov function is employed to improve control robustness by adjusting the varying parameters within their value ranges. This new controller also has the advantages of simple structure and ease of implementation. Simulation and experimental results demonstrate that the proposed controller can achieve higher control accuracy and stronger robustness. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Dynamic Torque Calibration Unit
Agronin, Michael L.; Marchetto, Carl A.
1989-01-01
Proposed dynamic torque calibration unit (DTCU) measures torque in rotary actuator components such as motors, bearings, gear trains, and flex couplings. Unique because designed specifically for testing components under low rates. Measures torque in device under test during controlled steady rotation or oscillation. Rotor oriented vertically, supported by upper angular-contact bearing and lower radial-contact bearing that floats axially to prevent thermal expansion from loading bearings. High-load capacity air bearing available to replace ball bearings when higher load capacity or reduction in rate noise required.
Kai-Hui Zhao
2017-06-01
Full Text Available To improve the accuracy of torque control for vector control of interior permanent-magnet synchronous machine (IPMSM, this study proposes a torque-sensorless control method based on cascaded sliding mode observer (SMO. First, the active flux model is discussed, which converts the model of IPMSM into the equivalent model of surface-mounted permanent-magnet synchronous machine. Second, to reduce chattering caused by system parameters variations and external disturbances, the cascaded observer is designed, which is composed of a variable gain adaptive SMO and an active flux SMO. The variable gain adaptive SMO is designed to estimate the speed, rotor position and stator resistance in the d–q reference frame. The active flux SMO is designed to estimate the active flux and torque in the α–β reference frame. Global asymptotic stability of the observers is guaranteed by the Lyapunov stability analysis. Finally, simulations and experiments are carried out to verify the effectiveness of the proposed control scheme.
基于转矩特性的开关磁阻电动机转矩控制%Torque Control of Switched Reluctance Motor Based on Torque Characteristics
荆建立; 吕思斌; 史成芳
2015-01-01
开关磁阻电动机的电磁关系具有高度非线性，传统的电机性能分析方法很难应用到其中。一般的开关磁阻电动机控制方法都需要磁链特性，但是开关磁阻电动机的磁链特性不易获取，由磁链计算转矩也非常复杂。笔者提出了一种不需磁链控制开关磁阻电动机转矩的方法，由实验实际测试开关磁阻电动机的转矩/转子位置/电流特性，根据转矩电流特性控制开关磁阻电动机的转矩。为了验证控制效果，组建了基于转矩特性的开关磁阻电动机转矩控制系统，实验结果表明该方法能精确地控制转矩。%The electromagnetic characteristics of switched reluctance motor was nonlinear and it was difficult to apply the traditional motor function analysis to switched reluctance motor. The common control method of switched reluctance motor needed flux linkage characteristics. But the acquirement of flux linkage characteristics was difficult and the torque calculation by the flux linkage was complicated. This paper proposed a torque control method of switched reluctance mo-tor,which didnˊt require flux linkage. The torque / rotor position / current characteristics were test-ed,the switched reluctance motor torque was controlled according to the torque characteristics. In order to verify the control effect,the torque control system of switched reluctance motor was built, which was based on the torque characteristics. The test results showed that the method could con-trol the torque accurately.
Chen, Weihai; Cui, Xiang; Zhang, Jianbin; Wang, Jianhua
2015-06-01
Rehabilitation technologies have great potentials in assisted motion training for stroke patients. Considering that wrist motion plays an important role in arm dexterous manipulation of activities of daily living, this paper focuses on developing a cable-driven wrist robotic rehabilitator (CDWRR) for motion training or assistance to subjects with motor disabilities. The CDWRR utilizes the wrist skeletal joints and arm segments as the supporting structure and takes advantage of cable-driven parallel design to build the system, which brings the properties of flexibility, low-cost, and low-weight. The controller of the CDWRR is designed typically based on a virtual torque-field, which is to plan "assist-as-needed" torques for the spherical motion of wrist responding to the orientation deviation in wrist motion training. The torque-field controller can be customized to different levels of rehabilitation training requirements by tuning the field parameters. Additionally, a rapidly convergent parameter self-identification algorithm is developed to obtain the uncertain parameters automatically for the floating wearable structure of the CDWRR. Finally, experiments on a healthy subject are carried out to demonstrate the performance of the controller and the feasibility of the CDWRR on wrist motion training or assistance.
Duli Ridlo Istriantono
2015-03-01
Full Text Available Robotics science has evolved significantly, driven by rapid advances in computer and sensor technology; and theoretical advances in control and computer vision. These development make widespread use of robot manipulators in industrial environments. Major problem in controlling a robot manipulator is to control the robot in order to achieve the desired position. Therefore the design issue of the robot control is to choose the right type controller. Computed Torque Controller (CTC is a powerful nonlinear controllers are widely used in the control of robot manipulators. CTC controller is designed based on feedback linearization and the required torque of the robot arm by using a nonlinear feedback control law. Simulation is done by providing joint trajectory from point to point. The simulation results show that the PD-Fuzzy-CTC controller is able to follow the joint trajectory with The RMSE value of the joint angle position of PD-Fuzzy-CTC controller is 10 times smaller than that of the PD-CTC controller with the end-effector position accuracy is 0.1 mm.
Emergency Entry with One Control Torque: Non-Axisymmetric Diagonal Inertia Matrix
Llama, Eduardo Garcia
2011-01-01
In another work, a method was presented, primarily conceived as an emergency backup system, that addressed the problem of a space capsule that needed to execute a safe atmospheric entry from an arbitrary initial attitude and angular rate in the absence of nominal control capability. The proposed concept permits the arrest of a tumbling motion, orientation to the heat shield forward position and the attainment of a ballistic roll rate of a rigid spacecraft with the use of control in one axis only. To show the feasibility of such concept, the technique of single input single output (SISO) feedback linearization using the Lie derivative method was employed and the problem was solved for different number of jets and for different configurations of the inertia matrix: the axisymmetric inertia matrix (I(sub xx) > I(sub yy) = I(sub zz)), a partially complete inertia matrix with I(sub xx) > I(sub yy) > I(sub zz), I(sub xz) not = 0 and a realistic complete inertia matrix with I(sub xx) > I(sub yy) > I)sub zz), I(sub ij) not= 0. The closed loop stability of the proposed non-linear control on the total angle of attack, Theta, was analyzed through the zero dynamics of the internal dynamics for the case where the inertia matrix is axisymmetric (I(sub xx) > I(sub yy) = I(sub zz)). This note focuses on the problem of the diagonal non-axisymmetric inertia matrix (I(sub xx) > I(sub yy) > I(sub zz)), which is half way between the axisymmetric and the partially complete inertia matrices. In this note, the control law for this type of inertia matrix will be determined and its closed-loop stability will be analyzed using the same methods that were used in the other work. In particular, it will be proven that the control system is stable in closed-loop when the actuators only provide a roll torque.
Karabulut, H.; Cinar, C.; Oztuerk, E.; Yuecesu, H.S. [Department of Mechanical Technology, Faculty of Technical Education, Gazi University, 06500 Teknikokullar, Ankara (Turkey)
2010-01-15
This study presents test results of a Stirling engine with a lever controlled displacer driving mechanism. Tests were conducted with helium and the working fluid was charged into the engine block. The engine was loaded by means of a prony type micro dynamometer. The heat was supplied by a liquefied petroleum gas (LPG) burner. The engine started to run at 118 C hot end temperature and the systematic tests of the engine were conducted at 180 C, 220 C and 260 C hot end external surface temperatures. During the test, cold end temperature was kept at 27 C by means of water circulation. Variation of the shaft torque and power with respect to the charge pressure and hot end temperature were examined. The maximum torque and power were measured as 3.99 Nm and 183 W at 4 bars charge pressure and 260 C hot end temperature. Maximum power corresponded to 600 rpm speed. (author)
A Systems Approach to the Torque Control of a Permanent Magnet Brushless Motor
1987-08-01
Direct Drive Arm (DDArni) and is addressed kinematic and dynamnic instabilities in robot force control . An presented parameter estimation techniques and...position and therefore cannot be guaranteed to remain stable. Eppinger and Seering [861 developed a dynamic model of robot force control with force
Munira, Kamaram; Pandey, Sumeet C.; Kula, Witold; Sandhu, Gurtej S.
2016-11-01
Voltage-controlled magnetic anisotropy (VCMA) effect has attracted a significant amount of attention in recent years because of its low cell power consumption during the anisotropy modulation of a thin ferromagnetic film. However, the applied voltage or electric field alone is not enough to completely and reliably reverse the magnetization of the free layer of a magnetic random access memory (MRAM) cell from anti-parallel to parallel configuration or vice versa. An additional symmetry-breaking mechanism needs to be employed to ensure the deterministic writing process. Combinations of voltage-controlled magnetic anisotropy together with spin-transfer torque (STT) and with an applied magnetic field (Happ) were evaluated for switching reliability, time taken to switch with low error rate, and energy consumption during the switching process. In order to get a low write error rate in the MRAM cell with VCMA switching mechanism, a spin-transfer torque current or an applied magnetic field comparable to the critical current and field of the free layer is necessary. In the hybrid processes, the VCMA effect lowers the duration during which the higher power hungry secondary mechanism is in place. Therefore, the total energy consumed during the hybrid writing processes, VCMA + STT or VCMA + Happ, is less than the energy consumed during pure spin-transfer torque or applied magnetic field switching.
Reyhanoglu, Mahmut
1996-01-01
There has been much interest over the past decade in the problem of asymptotic stabilization of the angular velocity of a rigid body with only two torque inputs. The smooth feedback laws proposed in the literature provide asymptotic stability with nonexponential convergence rates. This paper propose
Impact of feedback torque level on perceived comfort and control in steer-by-wire systems
Anand, S.; Terken, J.; Hogema, J.H.; Martens, J.B.
2012-01-01
Steer-by-Wire systems enable designers to offer completely personalized steering feel to drivers, unlike existing steering systems that offer limited or no personalization. In this paper we focus on feedback torque level, a significant factor for steering feel. Earlier studies indicate that the pref
Estimation for torques applied to the master side in a construction robot teleoperation system
Huang Lingtao
2016-01-01
Full Text Available The purpose of this research is to develop a method that measures a torque which an operator applies to the joystick without using a torque/force sensor on a joystick. We dealt with a construction robot teleoperation system which is comprised of two joysticks as the master, and an excavator with four degrees of freedom consisting of fork glove, swing, boom, and arm as the slave. It is necessary to know the torque (force exerted on the master side in force control. Because the joystick does not have a force/torque sensor in our lab, it is not possible to directly obtain the torque. To give prominence to the simple and practical construction robot teleoperation system in our lab, we proposed a method that measures the torque exerted on the joystick to existing equipment. Its effectiveness was verified by a reaction torque experiment.
闫佳麟; 蔡燕; 姜文涛
2014-01-01
Aiming at the problem of high torque ripple at low speed in traditional direct torque control system, a method of replacing reverse-vector with zero vector is proposed on the basis of analyzing and verifing the relationship between voltage vectors and torque ripple. Additionally, it is adopted to optimize the hysteresis controller of torque and flux linkage, both of which are utilized to solve the problem on high torque ripple. The simulation results indicate that this proposal can decrease torque from 4 N·m to 1.5 N·m, optimizes system performance and extends the low-speed range.%针对传统直接转矩控制系统存在低速运行时转矩脉动较大的问题，在对电压矢量和转矩脉动生成的关系进行分析和验证的基础上，提出了一种利用零矢量代替反向矢量的方案，同时对转矩和磁链的滞环控制器进行改进优化，用来解决转矩脉动大的问题.仿真结果表明：采用该方案后转矩脉动从4 N·m降至1.5 N·m左右，优化了系统性能，拓展了系统低速调节范围.
Bargallo, R.; Llaverias, J.; Martin, H. [Dept. Electrotecnia, Barcelona (Spain)
2000-08-01
After the work developed on parameter determination of saturated induction machines, now it is considered the estimation of not measurable variables such as flux and electromagnetic torque. Flux recursive estimation including parameter determination of saturated systems, leads to a torque observer that allows its evaluation. Torque measurement in dynamic operation is difficult and expensive. Here it is presented the implementation of an equipment for drive testing, which allows to generate arbitrary torque variations on the shaft of the driven machine, and also to measure and calculate electromechanical or load torques, by means of state observers. This work represents a previous step to the obtainment of an instant torque measurer-calibrator system. (orig.)
Kalaivani Lakshmanan
2014-01-01
Full Text Available In this paper, various intelligent controllers such as Fuzzy Logic Controller (FLC and Adaptive Neuro Fuzzy Inference System (ANFIS-based current compensating techniques are employed for minimizing the torque ripples in switched reluctance motor. FLC and ANFIS controllers are tuned using MATLAB Toolbox. For the purpose of comparison, the performance of conventional Proportional-Integral (PI controller is also considered. The statistical parameters like minimum, maximum, mean, standard deviation of total torque, torque ripple coefficient and the settling time of speed response for various controllers are reported. From the simulation results, it is found that both FLC and ANFIS controllers gives better performance than PI controller. Among the intelligent controllers, ANFIS gives outer performance than FLC due to its good learning and generalization capabilities thereby improves the dynamic performance of SRM drives.
Nonlinear dynamics of mini-satellite respinup by weak internal controllable torques
Somov, Yevgeny, E-mail: e-somov@mail.ru [Samara State Technical University, Department for Guidance, Navigation and Control, 244 Molodogvardeyskaya Str., Samara 443100 (Russian Federation)
2014-12-10
Contemporary space engineering advanced new problem before theoretical mechanics and motion control theory: a spacecraft directed respinup by the weak restricted control internal forces. The paper presents some results on this problem, which is very actual for energy supply of information mini-satellites (for communication, geodesy, radio- and opto-electronic observation of the Earth et al.) with electro-reaction plasma thrusters and gyro moment cluster based on the reaction wheels or the control moment gyros. The solution achieved is based on the methods for synthesis of nonlinear robust control and on rigorous analytical proof for the required spacecraft rotation stability by Lyapunov function method. These results were verified by a computer simulation of strongly nonlinear oscillatory processes at respinuping of a flexible spacecraft.
Camocardi, P. [LEICI, Universidad Nacional de La Plata, 1 y 47, CC 91 (1900) La Plata (Argentina); CONICET (Argentina); Battaiotto, P. [LEICI, Universidad Nacional de La Plata, 1 y 47, CC 91 (1900) La Plata (Argentina); Mantz, R. [LEICI, Universidad Nacional de La Plata, 1 y 47, CC 91 (1900) La Plata (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (Argentina)
2010-06-15
This paper presents and analyzes the operation strategy for an autonomous wind energy conversion system oriented to water pumping. It consists of a wind turbine with a Brushless Doubly-Fed Induction Generator (BDFIG), electrically coupled with a squirrel cage induction machine moving a centrifugal type water pump. Because of no brushes and slip rings, the BDFIG is suitable for autonomous systems, which often work in hard conditions. Additionally, the power flow on the BDFIG principal stator could be driven from a fractional power converter connected on the auxiliary stator winding. This Turbine-BDFIG and Motor-Pump configuration provides a high robustness and reliability, reducing the operational and maintenance costs. The operation strategy proposes, for wind speeds smaller than the rated, to maximize the volume of water pumped based on the optimization of the wind energy capture. To do that, a sliding mode control tracks the optimal turbine torque by means of a torque control. Meanwhile, for wind speeds greater than the rated, a pitch control keeps the water pump within the safe operation area by adjusting the speed and power of the turbine in their rated values. To assess and corroborate the proposed strategy, simulations with different wind profiles are made. (author)
Assessment of System Frequency Support Effect of PMSG-WTG Using Torque-Limit-Based Inertial Control
Wang, Xiao; Gao, Wenzhong; Wang, Jianhui; Wu, Ziping; Yan, Weihang; Gevorgian, Vahan; Zhang, Yingchen; Muljadi, Eduard; Kang, Moses; Hwang, Min; Kang, Yong Cheol
2017-02-16
To release the 'hidden inertia' of variable-speed wind turbines for temporary frequency support, a method of torque-limit based inertial control is proposed in this paper. This method aims to improve the frequency support capability considering the maximum torque restriction of a permanent magnet synchronous generator. The advantages of the proposed method are improved frequency nadir (FN) in the event of an under-frequency disturbance; and avoidance of over-deceleration and a second frequency dip during the inertial response. The system frequency response is different, with different slope values in the power-speed plane when the inertial response is performed. The proposed method is evaluated in a modified three-machine, nine-bus system. The simulation results show that there is a trade-off between the recovery time and FN, such that a gradual slope tends to improve the FN and restrict the rate of change of frequency aggressively while causing an extension of the recovery time. These results provide insight into how to properly design such kinds of inertial control strategies for practical applications.
Wang, Xiao; Gao, Wenzhong; Wang, Jianhui; Wu, Ziping; Yan, Weihang; Gevorgian, Vahan; Zhang, Yingchen; Muljadi, Eduard; Kang, Moses; Hwang, Min; Kang, Yong Cheol
2017-05-12
To release the 'hidden inertia' of variable-speed wind turbines for temporary frequency support, a method of torque-limit-based inertial control is proposed in this paper. This method aims to improve the frequency support capability considering the maximum torque restriction of a permanent magnet synchronous generator. The advantages of the proposed method are improved frequency nadir (FN) in the event of an under-frequency disturbance; and avoidance of over-deceleration and a second frequency dip during the inertial response. The system frequency response is different, with different slope values in the power-speed plane when the inertial response is performed. The proposed method is evaluated in a modified three-machine, nine-bus system. The simulation results show that there is a trade-off between the recovery time and FN, such that a gradual slope tends to improve the FN and restrict the rate of change of frequency aggressively while causing an extension of the recovery time. These results provide insight into how to properly design such kinds of inertial control strategies for practical applications.
Huang, Ting; Javaherian, Hossein; Liu, Derong
2011-06-01
This paper presents a new approach for the calibration and control of spark ignition engines using a combination of neural networks and sliding mode control technique. Two parallel neural networks are utilized to realize a neuro-sliding mode control (NSLMC) for self-learning control of automotive engines. The equivalent control and the corrective control terms are the outputs of the neural networks. Instead of using error backpropagation algorithm, the network weights of equivalent control are updated using the Levenberg-Marquardt algorithm. Moreover, a new approach is utilized to update the gain of corrective control. Both modifications of the NSLMC are aimed at improving the transient performance and speed of convergence. Using the data from a test vehicle with a V8 engine, we built neural network models for the engine torque (TRQ) and the air-to-fuel ratio (AFR) dynamics and developed NSLMC controllers to achieve tracking control. The goal of TRQ control and AFR control is to track the commanded values under various operating conditions. From simulation studies, the feasibility and efficiency of the approach are illustrated. For both control problems, excellent tracking performance has been achieved.
Xu, Kun; Xu, Guo-Qing; Zheng, Chun-Hua
2016-04-01
The wheel-rail adhesion control for regenerative braking systems of high speed electric multiple unit trains is crucial to maintaining the stability, improving the adhesion utilization, and achieving deep energy recovery. There remain technical challenges mainly because of the nonlinear, uncertain, and varying features of wheel-rail contact conditions. This research analyzes the torque transmitting behavior during regenerative braking, and proposes a novel methodology to detect the wheel-rail adhesion stability. Then, applications to the wheel slip prevention during braking are investigated, and the optimal slip ratio control scheme is proposed, which is based on a novel optimal reference generation of the slip ratio and a robust sliding mode control. The proposed methodology achieves the optimal braking performance without the wheel-rail contact information. Numerical simulation results for uncertain slippery rails verify the effectiveness of the proposed methodology.
Manipulating the voltage dependence of tunneling spin torques
Manchon, Aurelien
2012-10-01
Voltage-driven spin transfer torques in magnetic tunnel junctions provide an outstanding tool to design advanced spin-based devices for memory and reprogrammable logic applications. The non-linear voltage dependence of the torque has a direct impact on current-driven magnetization dynamics and on devices performances. After a brief overview of the progress made to date in the theoretical description of the spin torque in tunnel junctions, I present different ways to alter and control the bias dependence of both components of the spin torque. Engineering the junction (barrier and electrodes) structural asymmetries or controlling the spin accumulation profile in the free layer offer promising tools to design effcient spin devices.
C Krás Borges
2007-12-01
Full Text Available INTRODUÇÃO: Inúmeros casos de patologias em antebraço e cotovelo reportados na literatura estão associados com tarefas que envolvem esforço e movimentos repetitivos do braço e mão. A posição do cotovelo é conhecida por afetar a produção de torque máximo de supinação do antebraço, assim como é um fator crítico na determinação de exercícios terapêuticos apropriados. No entanto, baseado no que se conhece, não existem evidências sobre os efeitos da posição do cotovelo em tarefas que requerem controle de níveis submáximos de torque. OBJETIVO: Este estudo investigou o efeito da posição do cotovelo na produção de torque isométrico máximo de supinação do antebraço e no controle constante e contínuo de torque em diferentes níveis submáximos de torque. MÉTODOS: Dezesseis jovens adultos (24,7 ± 2,2 anos de idade foram solicitados a realizar duas tarefas: produção de torque máximo em pinça lateral (polegar e indicador e controle constante de torque em pinça lateral. Ambas as tarefas foram avaliadas em quatro posições do cotovelo (livre, 0º, 45º e 90º de flexão e três níveis submáximos de produção de torque em pinça lateral (20%, 40% e 60%. Torque máximo, variabilidade, irregularidade e precisão da resposta motora foram usados como variáveis dependentes. RESULTADOS: Maiores valores de torque foram encontrados quando a articulação do cotovelo não foi restringida. O controle de torque não foi influenciado pela posição da articulação do cotovelo. Maior variabilidade, irregularidade e menor precisão na resposta de torque foram registradas com o aumento progressivo dos níveis submáximos de torque. CONCLUSÃO: Os resultados sugerem que a posição do cotovelo não é um fator determinante para exercícios de reabilitação que incluam torque em supinação do antebraço.BACKGROUND: Large numbers of cases of pathological conditions in the forearm and elbow that have been reported in the
Hiroyuki NAKAMOTO
2007-04-01
Full Text Available Various humanoid robots have been developed and multifunction robot hands which are able to attach those robots like human hand is needed. But a useful robot hand has not been depeveloped, because there are a lot of problems such as control method of many degrees of freedom and processing method of enormous sensor outputs. Realizing such robot hand, we have developed five-finger robot hand. In this paper, the detailed structure of developed robot hand is described. The robot hand we developed has five fingers of multi-joint that is equipped with joint torque sensors and tactile sensors. We report experimental results of a stiffness control with the developed robot hand. Those results show that it is possible to change the stiffness of joints. Moreover we propose an object recognition method with the tactile sensor. The validity of that method is assured by experimental results.
Immediate effects of whole body vibration on patellar tendon properties and knee extension torque.
Rieder, F; Wiesinger, H-P; Kösters, A; Müller, E; Seynnes, O R
2016-03-01
Reports about the immediate effects of whole body vibration (WBV) exposure upon torque production capacity are inconsistent. However, the changes in the torque-angle relationship observed by some authors after WBV may hinder the measurement of torque changes at a given angle. Acute changes in tendon mechanical properties do occur after certain types of exercise but this hypothesis has never been tested after a bout of WBV. The purpose of the present study was to investigate whether tendon compliance is altered immediately after WBV, effectively shifting the optimal angle of peak torque towards longer muscle length. Twenty-eight subjects were randomly assigned to either a WBV (n = 14) or a squatting control group (n = 14). Patellar tendon CSA, stiffness and Young's modulus and knee extension torque-angle relationship were measured using ultrasonography and dynamometry 1 day before and directly after the intervention. Tendon CSA was additionally measured 24 h after the intervention to check for possible delayed onset of swelling. The vibration intervention had no effects on patellar tendon CSA, stiffness and Young's modulus or the torque-angle relationship. Peak torque was produced at ~70° knee angle in both groups at pre- and post-test. Additionally, the knee extension torque globally remained unaffected with the exception of a small (-6%) reduction in isometric torque at a joint angle of 60°. The present results indicate that a single bout of vibration exposure does not substantially alter patellar tendon properties or the torque-angle relationship of knee extensors.
Yang, Ruiping; Li, Renxian; Qin, Shitong; Ding, Chunying; Mitri, F. G.
2017-02-01
The effect of polarization on the optical spin torque (OST) exerted on an absorptive Rayleigh dielectric sphere by a vector Bessel beam is investigated using the dipole approximation method, with particular emphasis on the polarization of the plane wave component forming the beam. On the basis of the mathematical descriptions for the electric fields, which are derived using the angular spectrum decomposition method in plane waves, analytical formulas of the OST are established. The OSTs are numerically calculated, and the effects of polarization, beam-order, and half-cone angle are discussed in detail. Numerical results show that by choosing an appropriate polarization, order and half-cone angle, the transverse OST will manifest vortex-like behaviors, and the sphere will experience negative axial OSTs, i.e. OST sign reversal. Important applications in particle manipulation, rotation and handling using optical Bessel polarized beams would benefit from the results of the present investigation.
Limited Angle Torque Motors Having High Torque Density, Used in Accurate Drive Systems
R. Obreja
2011-01-01
Full Text Available A torque motor is a special electric motor that is able to develop the highest possible torque in a certain volume. A torque motor usually has a pancake configuration, and is directly jointed to a drive system (without a gear box. A limited angle torque motor is a torque motor that has no rotary electromagnetic field — in certain papers it is referred to as a linear electromagnet. The main intention of the authors for this paper is to present a means for analyzing and designing a limited angle torque motor only through the finite element method. Users nowadays require very high-performance limited angle torque motors with high density torque. It is therefore necessary to develop the highest possible torque in a relatively small volume. A way to design such motors is by using numerical methods based on the finite element method.
Charge-Induced Spin Torque in Anomalous Hall Ferromagnets
Nomura, Kentaro; Kurebayashi, Daichi
2015-09-01
We demonstrate that spin-orbit coupled electrons in a magnetically doped system exert a spin torque on the local magnetization, without a flowing current, when the chemical potential is modulated in a magnetic field. The spin torque is proportional to the anomalous Hall conductivity, and its effective field strength may overcome the Zeeman field. Using this effect, the direction of the local magnetization is switched by gate control in a thin film. This charge-induced spin torque is essentially an equilibrium effect, in contrast to the conventional current-induced spin-orbit torque, and, thus, devices using this operating principle possibly have higher efficiency than the conventional ones. In addition to a comprehensive phenomenological derivation, we present a physical understanding based on a model of a Dirac-Weyl semimetal, possibly realized in a magnetically doped topological insulator. The effect might be realized also in nanoscale transition materials, complex oxide ferromagnets, and dilute magnetic semiconductors.
Robust tuning of robot control systems
Minis, I.; Uebel, M.
1992-01-01
The computed torque control problem is examined for a robot arm with flexible, geared, joint drive systems which are typical in many industrial robots. The standard computed torque algorithm is not directly applicable to this class of manipulators because of the dynamics introduced by the joint drive system. The proposed approach to computed torque control combines a computed torque algorithm with torque controller at each joint. Three such control schemes are proposed. The first scheme uses the joint torque control system currently implemented on the robot arm and a novel form of the computed torque algorithm. The other two use the standard computed torque algorithm and a novel model following torque control system based on model following techniques. Standard tasks and performance indices are used to evaluate the performance of the controllers. Both numerical simulations and experiments are used in evaluation. The study shows that all three proposed systems lead to improved tracking performance over a conventional PD controller.
Hida, Hajime; Tomigashi, Yoshio; Ueyama, Kenji; Inoue, Yukinori; Morimoto, Shigeo
This paper proposes a new torque estimation method that takes into account the spatial harmonics of permanent magnet synchronous motors and that is capable of real-time estimation. First, the torque estimation equation of the proposed method is derived. In the method, the torque ripple of a motor can be estimated from the average of the torque calculated by the conventional method (cross product of the fluxlinkage and motor current) and the torque calculated from the electric input power to the motor. Next, the effectiveness of the proposed method is verified by simulations in which two kinds of motors with different components of torque ripple are considered. The simulation results show that the proposed method estimates the torque ripple more accurately than the conventional method. Further, the effectiveness of the proposed method is verified by performing on experiment. It is shown that the torque ripple is decreased by using the proposed method to the torque control.
Estimation of torque transmitted by clutch during shifting process for dry dual clutch transmission
Zhao, Zhiguo; He, Lu; Yang, Yunyun; Wu, Chaochun; Li, Xueyan; Karl Hedrick, J.
2016-06-01
The key toward realizing no-impact gear shifting for dual clutch transmission (DCT) lies in the coordination control between the engine and dual clutches, as well as the accurate closed-loop control of torque transmitted by each clutch and the output torque of the engine. However, the implementation and control precision of closed-loop control are completely dependent on the effective measurement or estimation of the instant transmission torque of the clutch. This study analyzes the DCT shifting process, and builds a three-dimensional (3D) clutch model and mathematical model of a DCT vehicle powertrain system. The torque transmitted by a twin clutch during the upshifting process is estimated by applying the unscented Kalman filter (UKF) algorithm. Then, the torque estimation algorithm is verified using a DCT prototype vehicle installed with a torque sensor on the drive half-shaft. The experimental results show that the designed UKF torque estimation algorithm can estimate the transmission torques of two clutches in real time; further, it can be directly used for DCT shift control and improving the shifting quality.
Optimizing Casimir torque between corrugated metallic plates
Rodrigues, Robson B. [Universidade Federal Fluminense, Niteroi, RJ (Brazil); Maia Neto, Paulo A. [Instituto de Fisica, Universidade Federal do Rio de Janeiro, RJ (Brazil)
2013-07-01
Full text: The Casimir effect plays a major role in micro- and nano-electromechanical systems (MEMS and NEMS). Besides the normal Casimir force between metallic or dielectric plates, the observation of the lateral Casimir force between corrugated plates opens novel possibilities of micro-mechanical control. The lateral force results from breaking the translational symmetry along directions parallel to the plates by imprinting periodic corrugations on both metallic plates. As the rotational symmetry is broken by this geometry, a Casimir torque arises when the corrugations are not aligned. We calculate the Casimir torque between two parallel metallic plates with surface profiles in the form of 'fans' with arbitrary relative spatial orientation. As compared to the case of anisotropic dielectric plates, the torque per unit area is increased by up to three orders of magnitude for a given separation distance. The experiment proposed here can be performed with torsion pendulum techniques for separation distances as large as 1 μm. From the point of view of fundamental physics, this torque makes possible a precise experimental investigation of the non-trivial geometry dependence of the Casimir effect. We follow the scattering approach and calculate the Casimir energy up to second order in the corrugation amplitudes, taking into account nonspecular reflections, polarization mixing and the finite conductivity of the metals. We investigate the experimental conditions that optimize the effect. (author)
Torque Balance Control in Fixed Join Two motor System%双电机同步连轴转矩均衡控制策略
严东超; 尹厚军; 王传秀
2015-01-01
Considering mandatory synchronization,torque coupling and parameter drifting among two brushless DC motors with synchronous shafts,a novel two��motor torque balance control scheme based on fuzzy control is presented.A double loop��closed control of speed control and torque balance is realized sim-ultaneously with meeting the speed control and power balance control system,in which torque servo master��slave control method is used.In speed control loop,the result of comparing given speed and the feedback speed of brushless DC motor gets access to the speed regulator to obtain the unified torque command.The other result of comparing the given speed and the torque feedback of brushless DC motors comes into the torque regulator to constitute two torque closed loops to rapidly follow the unified torque command.In Matlab/Simulink environment,the model of two motors torque balance control is built and a simulation of the working state of motors is conducted in normal and abnormal electrical parameters.The simulation re-sult shows that the proposed scheme is valid.%针对2台无刷直流电机同步连轴存在强制同速、转矩耦合以及参数漂移等问题，提出一种基于模糊控制的转矩均衡控制策略。构造速度和转矩双闭环均衡控制系统，同时满足系统的速度给定跟踪与转矩均衡控制。在速度控制环，给定转速与无刷直流电机反馈转速的转速差经过转速调节器，得到统一的转矩指令；2台电机反馈转矩与给定转矩分别进行比较，转矩差进入转矩调节器，构成2个转矩闭环，快速跟随转矩指令。在Matlab/Simulink 环境下，建立双电机同步连轴转矩均衡控制系统仿真模型，仿真对比了电机在参数一致和异常2种状况下直接转矩控制和模糊控制2种方案的结果，验证了所提控制策略的有效性。
Design and Control of a Closed-Loop Brushless Torque Activator
1990-05-01
BIBLIOGRAPHY 106 [Eppinger 87] Eppinger, S.D., and Seering, W.P., "Understanding Bandwidth Limitations in Robot Force Control ," proc. 1987 IEEE International...ment, and Control, vol. 99, no. 2, June 1977, pp. 91-97. [Whitney 85] Whitney, D.E., "Historical Perspective and State of the Art in Robot Force Control ," proc
Mello, Emanuele Moraes; Magalhães, Fernando Henrique; Kohn, André Fabio
2013-12-01
The present study examined the association between plantar flexion torque variability during isolated isometric contractions and during quiet bipedal standing. For plantar flexion torque measurements in quiet stance (QS), subjects stood still over a force plate. The mean plantar flexion torque level exerted by each subject in QS (divided by 2 to give the torque due to a single leg) served as the target torque level for right leg force-matching tasks in extended knee (KE) and flexed knee (KF) conditions. Muscle activation levels (EMG amplitudes) of the triceps surae and mean, standard deviation and coefficient of variation of plantar flexion torque were computed from signals acquired during periods with and without visual feedback. No significant correlations were found between EMG amplitudes and torque variability, regardless of the condition and muscle being analyzed. A significant correlation was found between torque variability in QS and KE, whereas no significant correlation was found between torque variability in QS and KF, regardless of vision availability. Therefore, torque variability measured in a controlled extended knee plantar flexion contraction is a predictor of torque variability in the anterior-posterior direction when the subjects are in quiet standing. In other words, larger plantar flexion torque variability in KE (but not in KF) implies less stable balance. The mechanisms underlying the findings above are probably associated with the similar proprioceptive feedback from the triceps surae in QS and KE and poorer proprioceptive feedback from the triceps surae in KF due to the slackening of the gastrocnemii. An additional putative mechanism includes the different torque contributions of each component of the triceps surae in the two knee angles. From a clinical and research standpoint, it would be advantageous to be able to estimate changes in balance ability by means of simple measurements of torque variability in a force matching task.
Fukushima, Edwardo F.; Hirose, Shigeo [Tokyo Inst. of Tech. (Japan)
2000-05-01
This paper introduces an attitude control scheme based in optimal force distribution using quadratic programming which minimizes joint energy consumption. This method shares similarities with force distribution for multifingered hands, multiple coordinated manipulators and legged walking robots. In particular, an attitude control scheme was introduced inside the force distribution problem, and successfully implemented for control of the articulated body mobile robot KR-II. This is an actual mobile robot composed of cylindrical segments linked in series by prismatic joints and has a long snake-like appearance. These prismatic joints are force controlled so that each segment's vertical motion can automatically follow the terrain irregularities. An attitude control is necessary because this system acts like a system of wheeled inverted pendulum carts connected in series, being unstable by nature. The validity and effectiveness of the proposed method is verified by computer simulation and experiments with the robot KR-II. (author)
Senserless Speed and Position of Direct Field Orientation Control Induction Motor Drive
Mohammed Khalil Hussain
2012-01-01
Full Text Available Direct field-orientation Control (DFOC of induction motor drives without mechanical speed sensors at the motor shaft has the attractions of low cost and high reliability. To replace the sensor, information on the rotor speed and position are extracted from measured stator currents and from voltages at motor terminals. In this paper presents direct field-orientation control (DFOC with two type of kalman filter (complete order and reduced order extended kalman filter to estimate flux, speed, torque and position. Simulated results show how good performance for reduced order extended kalman filter over that of complete order extended kalman filter in tracking performance and reduced time of state estimation.
Okabayashi, M. [PPPL; Zanca, P. [Euratom-ENEA; Strait, E. J. [General Atomics
2014-09-01
Disruptions caused by tearing modes (TMs) are considered to be one of the most critical roadblocks to achieving reliable, steady-state operation of tokamak fusion reactors. Here we have demonstrated a very promising scheme to avoid such disruptions by utilizing the electro-magnetic (EM) torque produced with 3D coils that are available in many tokamaks. In this scheme, the EM torque to the modes is created by a toroidal phase shift between the externally-applied field and the excited TM fields, compensating for the mode momentum loss due to the interaction with the resistive wall and uncorrected error fields. Fine control of torque balance is provided by a feedback scheme. We have explored this approach in two vastly different devices and plasma conditions: DIII-D and RFX-mod operated in tokamak mode. In DIII-D, the plasma target was high βN plasmas in a non-circular divertor tokamak. In RFX-mod, the plasma was ohmically-heated plasma with ultralow safety factor in a circular limiter discharge of active feedback coils outside the thick resistive shell. The DIII-D and RFX-mod experiments showed remarkable consistency with theoretical predictions of torque balance. The application to ignition-oriented devices such as International Thermonuclear Experimental Reactor (ITER) would expand the horizon of its operational regime. The internal 3D coil set currently under consideration for edge localized mode suppression in ITER would be well suited to this purpose.
Heleodório Honorato dos Santos
2014-12-01
Full Text Available This study investigated the effects of the isokinetic eccentric training (IET on the knee extensor and flexor torque and kinematic gait parameters in individuals with ACL reconstruction. Sixteen men with ACL reconstructed (ACLr whose torque and the gait were evaluated, before and after 12 weeks of IET, was compared to a control group (14 individuals. Student t, MANOVA and ANOVA tests were performed with 5% of significance. The training increased the isometric, concentric at 30 and 120º/s (p < .05 and eccentric at 30º/s (p < .01 extensor torque on the affected limb (AL, and eccentric at 30 and 120º/s (p < .01, on the non-affected limb (NAL. In the flexors, there was an increase on the torque: isometric, concentric at 30º/s and eccentric at 30 and 120º/s (p < .01 in AL and in eccentric at 30 (p < .05 and 120º/s (p< .01 in NAL. With respect to the angular and spatio-temporal variables gait, there was no difference between pre-and post-training in LCAr group. Compared to control group, the cycle time, in two members, was lower in LCAr group, and stride length and cadence were higher in the AL of the LCAr (p < .05. Moreover, the knee flexion-extension angles (minimum and maximum remained lower in LCAr, pre- and post-training (p < .01. The torque gain associated with eccentric isokinetic training did not affect the kinematic parameters of gait in patients undergoing ACL reconstruction.
吴春华; 陈国呈; 孙承波
2007-01-01
In order to deal with torque pulsation problem caused by traditional control method for brushless DC(BLDC)motor and to achieve high precision and good stability,a novel control strategy is proposed.Compared with the traditional control scheme,by using phase voltage as a control objective and making waveform of phase current approximately quasi-sinusoidal,torque ripple of BLDC motor is reduced from the original 14% to 3.4%,while toque is increased by 3.8%.Furthermore,by detecting zero-crossings of back electromotive force(BEMF)with non-conducting phases,sensorless control is realized.The new control strategy is simple.It carl minimize torque ripple,increase torque,and realize sensorless control for BLDC motor.Simulation and experiments show good performance of BLDC motor by using the new control method.
Cogging torque reduction for interior permanent magnet synchronous motors
Tost Candel, Miquel
2015-01-01
Interior permanent magnet synchronous machines show a good range of behaviours, which make these kinds of machines good candidates for an electromechanical energy conversion. However, in order to improve their accuracy in their torque responses, the cogging torque and torque ripple phenomena should be mitigated to obtain better performance of the machine. In order to reduce the cogging torque and torque ripple, control techniques as well as geometric parameters of the machine have to be im...
抑制PMSM周期性转矩脉动的迭代学习方法%PMSM periodical torque ripple minimization using iterative learning control
李兵强; 林辉
2011-01-01
To minimize the low speed torque ripple of permanent magnet synchronous motor ( PMSM) used in high-performance servo system, the traditional torque ripple suppression methods were discussed, the main components of torque ripple were analyzed and its periodic characteristic was pointed out. Based on these, a new method using iterative learning control (ILC) was proposed to minimize the periodic torque ripple of PMSM with constant voltage frequency ratio control. The method minimizes the torque ripple by on line learning and compensating the control voltage. The controller was designed and its convergence condition was derived. The simulation results show that the iterative learning process has fast convergence speed and the torque ripple can be effectively minimized from 11. 2% to 3. 1 %. This method needs a small amount of changes to the original system, the structure and algorithm are both simple and do not depend on the prior system knowledge and parameters, thus can obtain strong robustness.%为了抑制永磁同步电机高性能伺服应用中的低速转矩脉动,在探讨转矩脉动传统抑制方法的基础上,分析并指出主要成分的周期特性,提出永磁同步电机恒压频比控制中通过迭代学习控制抑制周期性转矩脉动的方法,通过在线学习补偿电机控制电压来抑制转矩脉动,设计了控制器并作了收敛性分析.仿真结果表明:迭代学习快速收敛,可有效减小转矩脉动,转矩纹波系数由初始时刻的11.2％减小为3.1％.该方法对原系统改动量小,结构与算法实现简单,不依赖于系统的先验知识和系统参数,鲁棒性强.
Mauldin, Rebecca H.
2010-01-01
In order to study and control the attitude of a spacecraft, it is necessary to understand the natural motion of a body in orbit. Assuming a spacecraft to be a rigid body, dynamics describes the complete motion of the vehicle by the translational and rotational motion of the body. The Simulink Attitude Analysis Model applies the equations of rigid body motion to the study of a spacecraft?s attitude in orbit. Using a TCP/IP connection, Matlab reads the values of the Remote Manipulator System (RMS) hand controllers and passes them to Simulink as specified torque and impulse profiles. Simulink then uses the governing kinematic and dynamic equations of a rigid body in low earth orbit (LE0) to plot the attitude response of a spacecraft for five seconds given known applied torques and impulses, and constant principal moments of inertia.
Lascu, Cristian; Boldea, Ion; Blaabjerg, Frede
2004-01-01
A family of speed-sensorless sliding-mode observers for induction motors has been developed. Three topologies have been investigated in order to determine their feasibility, parameter sensitivity and practical applicability. The salient feature of all schemes is that they do not require the rotor...
Fatih Korkmaz
2012-12-01
Full Text Available The International Journal of Computer Networks & Communications (IJCNC is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications.The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new collaborations in these areas.
Fatih Korkmaz; M.Faruk Çakır; İsmail Topaloğlu; Rıza Gürbüz
2012-01-01
The International Journal of Computer Networks & Communications (IJCNC) is a bi monthly open access peer-reviewed journal that publishes articles which contribute new results in all areas of Computer Networks & Communications.The journal focuses on all technical and practical aspects of Computer Networks & data Communications. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced networking concepts and establishing new col...
Direct Torque Control of a Three-Phase Voltage Source Inverter-Fed Induction Machine
2013-12-01
techniques have been proven effective, each technique possesses its own advantages and disadvantages. In today’s engineering world , time and money...three techniques have been proven effective, each technique possesses its own advantages and disadvantages. In today’s engineering world , time and...distributed on the stator iron and either three-phase windings wound on the rotor or an equivalent squirrel - cage structure. Applying balanced three-phase
Moghadam, M Nassajian; Aminian, K; Asghari, M; Parnianpour, M
2013-01-01
The way central nervous system manages the excess degrees of freedom to solve kinetic redundancy of musculoskeletal system remains an open question. In this study, we utilise the concept of synergy formation as a simplifying control strategy to find the muscle recruitment based on summation of identified muscle synergies to balance the biomechanical demands (biaxial external torque) during an isometric shoulder task. A numerical optimisation-based shoulder model was used to obtain muscle activation levels when a biaxial external isometric torque is imposed at the shoulder glenohumeral joint. In the numerical simulations, 12 different shoulder torque vectors in the transverse plane are considered. For each selected direction for the torque vector, the resulting muscle activation data are calculated. The predicted muscle activation data are used for grouping muscles in some fixed element synergies by the non-negative matrix factorisation method. Next, torque produced by these synergies are computed and projected in the 2D torque space to investigate the magnitude and direction of torques that each muscle synergy generated. The results confirmed our expectation that few dominant synergies are sufficient to reconstruct the torque vectors and each muscle contributed to more than one synergy. Decomposition of the concatenated data, combining the activation and external torque, provided functional muscle synergies that produced torques in the four principal directions. Four muscle synergies were able to account for more than 95% of variation of the original data.
Reaction torque minimization techniques for articulated payloads
Kral, Kevin; Aleman, Roberto M.
1988-01-01
Articulated payloads on spacecraft, such as antenna telemetry systems and robotic elements, impart reaction torques back into the vehicle which can significantly affect the performance of other payloads. This paper discusses ways to minimize the reaction torques of articulated payloads through command-shaping algorithms and unique control implementations. The effects of reaction torques encountered on Landsat are presented and compared with simulated and measured data of prototype systems employing these improvements.
Directional and Attitude Stability Control Kit
2014-07-01
and Attitude Stability Control Kit Final Progress Report This report outlines progress on the DARPA M3 Program, project “Directional and Attitude ...2 ABSTRACT Number of Papers published in peer-reviewed journals: Number of Papers published in non peer-reviewed journals: Directional and Attitude ...Stability Control Kit Final Progress Report Report Title This report outlines progress on the DARPA M3 Program, project “Directional and Attitude
ISG混合动力电动汽车的转矩控制策略%Torque Control Strategy for ISG Hybrid Electric Vehicles
邓国红; 周挺; 杨鄂川; 欧健; 张勇
2014-01-01
The torque becomes the most important controllable factor for an ISG( integrated starter/generator)parallel hybrid electric vehicle of energy management strategy. Therefore,energy manage-ment must consider how to employ a torque approach. For the ISG HEV,based upon the operating modes of the hybrid power train,a fuzzy inference engine of a torque distribution controller is con-structed by using the ratio of the driver required torque to the current optimal torque of engine and the battery state-of-charge( SOC)as the inputs,and the motor torque instructions as the output. The dy-namic performance,fuel economy and battery state of charge( SOC)are simulated in the NEDC typi-cal driving cycle by vehicle simulation software ADVISOR. The simulation results indicate that,com-pared with the strategy which uses threshold parameters,the proposed strategy both improves fuel e-conomy of the vehicle and maintains SOC of the battery within its operation range more effectively in a extent.%转矩为ISG混合动力电动汽车能量管理策略中最主要的控制变量，其实质为转矩分配策略。针对ISG并联混合动力轿车，根据混合动力系统的工作模式，以需求转矩与发动机当前最佳效率转矩的比值和蓄电池荷电状态（ SOC ）为输入，以电机转矩指令为输出，构建了转矩分配模糊控制器。基于仿真软件ADVISOR，选用 NEDC道路循环工况进行了仿真分析。结果表明：与传统门限控制策略相比，该模糊控制器在一定程度上更有效地降低了混合动力电动汽车的燃油消耗量，并且保持电池组SOC在工作区间的平衡。
Oberstrass, Florian C.; Fernandes, Louis E.; Lebel, Paul; Bryant, Zev
2013-01-01
Changes in global DNA linking number can be accommodated by localized changes in helical structure. We have used single-molecule torque measurements to investigate sequence-specific strand separation and Z-DNA formation. By controlling the boundary conditions at the edges of sequences of interest, we have confirmed theoretical predictions of distinctive boundary-dependent backbending patterns in torque-twist relationships. Abrupt torque jumps are associated with the formation and collapse of DNA bubbles, permitting direct observations of DNA breathing dynamics. PMID:23679785
Reduction of torque ripple in DTC induction motor drive with discrete voltage vectors
Rosić Marko
2014-01-01
Full Text Available This paper presents а practical implementation of direct torque control (DTC of an induction machine on MSK2812 DSP platform, and the analysis of possibilities for reduction of torque ripple. Basic theoretical background relating the DTC was primarily set and the obtained experimental results have been given. It is shown that the torque ripple can be reduced by adjusting the intensity of voltage vectors and by modification of hysteresis comparator, while the simplicity of the basic DTC algorithm has been maintained. [Projekat Ministarstva nauke Republike Srbije, br. TR33016
Forces and torques between nonintersecting straight currents
Binder, P.-M.; Cross, Felicity; Silva, J. K.
2016-07-01
We analyse two very long current-carrying straight wires that point in arbitrary directions without touching. We find general expressions for the forces and torques for arbitrary points on one wire due to the other. This allows us to make calculations for the overall forces and torques and statements about the stability of parallel and anti-parallel current arrangements.
Bo Long; Shin Teak Lim; Ji Hyoung Ryu; Kil To Chong
2013-01-01
Regenerative braking provides an effective way of extending the driving range of battery powered electric vehicles (EVs). This paper analyzes the equivalent power circuit and operation principles of an EV using regenerative braking control technology. During the braking period, the switching sequence of the power converter is controlled to inverse the output torque of the three-phase brushless direct-current (DC) motor, so that the braking energy can be returned to the battery. Compared with ...
M. K. Metwally
2013-11-01
Full Text Available This paper presents a cost-effective vector control strategy for four switch three phase (FSTP inverter fed a synchronous reluctance motor with conventional rotor (SynRM drive. The reduction of the number of power switches from six to four improves the cost-effectiveness, volume-compactness and reliability of the three phase inverters. In this paper, a simulation model of the drive system is developed and analyzed in order to verify the effectiveness of the approach. The application of vector control to a SynRM at maximum torque control (MTC operation is presented with emphasis on the effects of saturation and iron losses are briefly considered. A PI controller is used to process the speed error. Two independent hysteresis current controllers with a suitable hysteresis band are utilized for inverter switches signals. A simplified steady-state d-q model including saturation and iron losses is presented. Simulation results show that the drive system provides a fast speed response and good disturbance rejection capability.
Okabayashi, M.; Zanca, P.; Strait, E. J.; Garofalo, A. M.; Hanson, J. M.; In, Y.; La Haye, R. J.; Marrelli, L.; Martin, P.; Paccagnella, R.; Paz-Soldan, C.; Piovesan, P.; Piron, C.; Piron, L.; Shiraki, D.; Volpe, F. A.; DIII-D, The; RFX-mod Teams
2017-01-01
Disruptions caused by tearing modes (TMs) are considered to be one of the most critical roadblocks to achieving reliable, steady-state operation of tokamak fusion reactors. Here we have demonstrated a promising scheme to avoid mode locking by utilizing the electro-magnetic (EM) torque produced with 3D coils that are available in many tokamaks. In this scheme, the EM torque is delivered to the modes by a toroidal phase shift between the externally applied field and the excited TM fields, compensating for the mode momentum loss through the interaction with the resistive wall and uncorrected error fields. Fine control of torque balance is provided by a feedback scheme. We have explored this approach in two widely different devices and plasma conditions: DIII-D and RFX-mod operated in tokamak mode. In DIII-D, the plasma target was high β N in a non-circular divertor tokamak. Here β N is defined as β N = β/(I p /aB t) (%Tm/MA), where β, I p, a, B t are the total stored plasma pressure normalized by the magnetic pressure, plasma current, plasma minor radius and toroidal magnetic field at the plasma center, respectively. The RFX-mod plasma was ohmically-heated with ultra-low safety factor in a circular limiter discharge with active feedback coils outside the thick resistive shell. The DIII-D and RFX-mod experiments showed remarkable consistency with theoretical predictions of torque balance. The application to ignition-oriented devices such as the International Thermonuclear Experimental Reactor (ITER) would expand the horizon of its operational regime. The internal 3D coil set currently under consideration for edge localized mode suppression in ITER would be well suited for this purpose.
Palmer, Ty B; Hawkey, Matt J; Thiele, Ryan M; Conchola, Eric C; Adams, Bailey M; Akehi, Kazuma; Smith, Doug B; Thompson, Brennan J
2015-07-01
The purpose of this study was to examine the effectiveness of maximal and rapid isometric torque characteristics of the hip extensor muscles and postural balance performance to discriminate between female collegiate soccer athletes and non-athlete controls. Ten athletes (mean ± SE: age = 19·20 ± 0·36 year; mass = 62·23 ± 3·12 kg; height = 162·43 ± 1·70 cm) and 10 non-athletes (age = 20·30 ± 0·40 year; mass = 69·64 ± 3·20 kg; height = 163·22 ± 2·10 cm) performed two isometric maximal voluntary contractions (MVCs) of the hip extensor muscles. Peak torque (PT) and absolute and relative rate of torque development (RTD) at early (0-50 ms) and late (100-200 ms) phases of muscle contraction were examined during each MVC. Postural balance was assessed using a commercially designed balance testing device, which provides a measurement of static stability based on sway index (SI). Results indicated that absolute and relative RTD at 0-50 ms (RTD50 and RTD50norm) were greater (P = 0·007 and 0·026), and postural SI was lower (P = 0·022) in the athletes compared with the non-athletes. However, no differences (P = 0·375-0·709) were observed for PT nor absolute and relative RTD at 100-200 ms (RTD100-200 and RTD100-200norm). Significant relationships were also observed between RTD50 and RTD50norm and SI (r = -0·559 and -0·521; P = 0·010 and 0·019). These findings suggest that early rapid torque characteristics of the hip extensor muscles and postural balance performance may be sensitive and effective measures for discriminating between college-aged athletes and non-athletes. Coaches and practitioners may use these findings as performance evaluation tools to help in identifying athletes with both superior early rapid torque and balance performance abilities, which may possibly be an indicator of overall athletic potential.
A Research on Engine Torque Control in Shifting Process%换挡过程中发动机转矩控制的研究
高金武; 刘志远; Zheng Quan
2012-01-01
根据发动机平均值模型,将节气门开度和点火角作为输入量,充分利用了节气门调节范围大、但响应速度慢,而点火角响应速度快、但调节范围有限的特点,结合控制量分配技术,提出了一种换挡过程的发动机转矩调节策略.在Matlab/Simulink环境下对控制器进行了仿真验证,结果表明,所提出的换挡过程发动机转矩控制策略能有效抑制输出轴的转矩波动,提高换挡舒适性.%Based on engine mean value model, with throttle opening and ignition angle as inputs and fully utilizing the features of throttle opening (wide regulation range but with slow response) and ignition angle (quick response but with limited adjusting range) , a shift control strategy with engine torque regulation is proposed by using control allocation technique. The controller is validated by simulation with Matlab/Simulink, and the results show that the shift control strategy proposed can effectively suppress the torque fluctuation of output shaft and hence improve shift comfort.
Abdelkrim Thameur
2015-01-01
Full Text Available This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.
Controlled quantum teleportation and secure direct communication
Gao Ting; Yan Feng-Li; Wang Zhi-Xi
2005-01-01
We present a controlled quantum teleportation protocol. In the protocol, quantum information of an unknown state of a 2-level particle is faithfully transmitted from a sender Alice to a remote receiver Bob via an initially shared triplet of entangled particles under the control of the supervisor Charlie. The distributed entangled particles shared by Alice, Bob and Charlie function as a quantum information channel for faithful transmission. We also propose a controlled and secure direct communication scheme by means of this teleportation. After ensuring the security of the quantum channel, Alice encodes the secret message directly on a sequence of particle states and transmits them to Bob supervised by Charlie using this controlled quantum teleportation. Bob can read out the encoded message directly by the measurement on his qubit. In this scheme, the controlled quantum teleportation transmits Alice's message without revealing any information to a potential eavesdropper. Because there is not a transmission of the qubit carrying the secret message between Alice and Bob in the public channel, it is completely secure for controlled and direct secret communication if perfect quantum channel is used. The special feature of this scheme is that the communication between two sides depends on the agreement of a third side to co-operate.
王萌; 周徐斌; 杜三虎; 王智磊
2016-01-01
As a typical space structure, multi-link deployable structures use a lot of structural or ca-ble synchronous devices for motion control.To reduce the complexity of deployable structures and a-void the disadvantage of traditional synchronous devices, a new motion control method:torque con-trol method was proposed in this paper.Through the study of three-link system’ s kinematic charac-teristics, driving torque was identified as the key parameter of synchronization.In order to achieve the orderly expansion, three-link system must allocate values for all the driving torques logically. Compared with the traditional mechanical devices’ compelling synchronization, the new torque con-trol method could achieve synchronization by torque value precision design.In the practical applica-tion, in order to simplify the parameter selection, constant-torque spring replaced the Archimedes spiral spring as the driving device.Based on the deployable structure’ s kinematic model, springs’ values were obtained by the design evaluation tool in ADAMS.The final results showed that the a-synchronous deployable time was less than 0.3s, which could meet the application requirement.%多连杆展开结构作为一种典型的空间展开结构，需要通过机械或绳索同步装置进行展开运动控制。为有效降低展开系统的复杂度，避免传统机械同步装置的不足，提出了一种新型运动控制方法：力矩控制法。通过分析3连杆系统的运动特性，确定了系统各展开轴线上的驱动力矩是控制同步性的关键参数。为实现有序展开，3连杆系统需要在运动过程中合理分配各驱动力矩值。传统的机械同步装置是强制保持力矩平衡以实现同步性，而力矩控制法则是通过精确设计各力矩值实现展开同步的。在实际工程应用中，为简化参数选取难度，采用恒力矩驱动弹簧代替阿基米德涡卷弹簧作为系统动力源。在建立展开结构的动力
Climate modification directed by control theory
Liang, Wang
2008-01-01
Climate modification measures to counteract global warming receive some more new attentions in these years. Most current researches only discuss the impact of these measures to climate, but how to design such a climate regulator is still unknown. This paper shows the control theory could give the systematic direction for climate modification. But the control analyzing also reveals that climate modifications should only be regarded as a last-ditch measure.
Wei Wang
2012-05-01
Full Text Available This paper proposes a novel optimal current given (OCG maximum power point tracking (MPPT control strategy based on the theory of power feedback and hill climb searching (HCS for a permanent magnet direct drive wind energy conversion system (WECS. The presented strategy not only has the advantages of not needing the wind speed and wind turbine characteristics of the traditional HCS method, but it also improves the stability and accuracy of MPPT by estimating the exact loss torque. The OCG MPPT control strategy is first carried out by simulation, then an experimental platform based on the dSPACE1103 controller is built and a 5.5 kW permanent magnet synchronous generator (PMSG is tested. Furthermore, the proposed method is compared experimentally with the traditional optimum tip speed ratio (TSR MPPT control. The experiments verify the effectiveness of the proposed OCG MPPT strategy and demonstrate its better performance than the traditional TSR MPPT control.
Efficient Controlled Quantum Secure Direct Communication Protocols
Patwardhan, Siddharth; Moulick, Subhayan Roy; Prasanta K. Panigrahi
2015-01-01
We study controlled quantum secure direct communication (CQSDC), a cryptographic scheme where a sender can send a secret bit-string to an intended recipient, without any secure classical channel, who can obtain the complete bit-string only with the permission of a controller. We report an efficient protocol to realize CQSDC using Cluster state and then go on to construct a (2-3)-CQSDC using Brown state, where a coalition of any two of the three controllers is required to retrieve the complete...
Tip and Torque Angle of Permanent Teeth: A Comparison Between Treated Patients and Normal Group
A.F. Miresmaeili
2005-01-01
Full Text Available The angle of long axis of tooth crown is called tip in mesiodostal and torque in faciolingual direction. Both have special importance for producing an ideal occlusion. The aim of the present study was determination of the average tip and torque of each permanent tooth in well treated patients with edgewise system compare to control group with normal occlusion. In this study, 19 well treated cases through standard edgewise technique with non extraction strategy and 20 students of pre-university schools with normal occlusion according to IOTN were selected. Reference points and lines were marked on facial surface of each tooth on casts. Special device was designed for measuring the faciolingual and mesiodistal inclination of crowns. After 3 times measuring the tip and torque of teeth, student t-test and Kruskal – Wallis analysis were used for statistical analysis.The mean age of control group was 18.8 ± 0.5 year and in treated group was 20.3 ± 0.8. There was significant difference between mean of torque in control group and treated group for upper lateral incisor (4.75±5.21 , 8.76±5.82 respectively , p<0.03 . Also a significant difference was seen in average torque of lower second premolar between control group and treated one ( -23.48±5.99 , -26.66±4.64 respectively , p<0.05. There were no significant differences in tip of teeth between two groups. In comparison with Andrews study, in normal occlusion group, upper canine & first molar and lower lateral & first premolar had more buccal root torque. Except the torque of upper lateral incisor and lower 2nd premolar, torque and tip of other teeth had no significant difference.
王志强; 房建成
2011-01-01
In order to solve the problem of reaction flywheel motor torque ripple effecting satellite attitude control accuracy, the flywheel motor commutation torque ripple minimization conditions are derived by adopting the analytical method of permanent magnet brushless DC motor induced electromotive force, phase current and electromagnetic torque,and a highly dynamic aynergetic control approach is proposed based on the commutation torque ripple minimum conditions.The approach is Used to restrain commutation torque ripple of reaction flywheel under different operating conditions. The experiment results show that the commutation torque ripple decreases by 12％ in the electrical mode, and the commutation torque ripple is reduced by 90％ or more in controlled braking and reverse braking modes, thus verifying feasibility and effectiveness of the control approach.%针对反作用飞轮电机换相所产生的非理想力矩影响卫星姿态控制精度的问题,采用永磁无刷直流电机绕组感生电势、相电流和电磁转矩的解析计算方法得到了反作用飞轮电机的换相力矩波动最小化条件,提出了基于该最小化条件的换相力矩波动抑制高动态协同控制方法,抑制反作用飞轮电机三种运行状态下的换相力矩波动.试验结果表明,电动状态下换相力矩波动减小了12%、可控能耗制动和反接制动状态下换相力矩波动减小了90%以上,验证了该方法的可行性和有效性.
无
2007-01-01
This paper develops a unified methodology for a real-time speed control of brushless direct-current motor drive systems in the presence of measurement noise and load torque disturbance. First, the mathematical model and hardware structure of system is established. Next, an optimal state feed back controller using the Kalman filter state estimation technique is derived.This is followed by an adaptive control algorithm to compensate for the effects of noise and disturbance. Those two algorithms working together can provide a very-high-speed regulation and dynamic response over a wide range of operating conditions.Simulated responses are presented to highlight the effectiveness of the proposed control strategy.
王帅; 王建立; 李洪文; 阴玉梅
2012-01-01
An improved active disturbance rejection control is proposed to solve the problem on the velocity fluctuation caused by torque ripples in a DC torque motor. The algorithm consists of two parts: the extended state observer estimates the system disturbances, and then the estimated disturbance is fed into the control system to form composite correction system. A two-parameter proportional-derivative controller can guarantee system stability and good dynamic characteristics. The simulation and experimental results show that, compared to the PI controller with the same closed-loop control bandwidth, the proposed method can improve the ability of disturbance rejection, using Active Disturbance Rejection Control (ADRC) compensation, the peak-peak value of speed error from 1.88% down to 0.65%, the Root Mean Square (RMS) value of the error from 0.8% to 0.2%. Experimental results show that the proposed method can effectively reduce the velocity fluctuation caused by motor torque ripple, and improve the speed smooth.%为解决光电跟踪伺服系统受电机力矩波动影响产生的速度波动问题,提出了一种改进的自抗扰控制策略进行力矩波动补偿.该算法主要由两部分组成:通过扩张状态观测器辨识出系统扰动,然后将该扰动前馈到系统控制量中去,构成复合校正系统；反馈通道中采用两参数的比例微分控制器,可以保证系统的稳定性和良好的动态特性.仿真分析和实验结果表明:与同等闭环控制带宽的PI控制器相比,自抗扰控制器可以提高系统对扰动力矩的抑制能力,采用自抗扰补偿时,速度误差的峰值由1.88％降低到0.65％,速度误差的均方根值由0.8％降低到0.2％.实验结果证明提出的方法能够有效降低电机力矩波动的影响,提高速度平稳性.
Comparison of two kinds of brackets on torque control%两种托槽对转矩控制影响的比较研究
田军; 柳忠豪; 刘利苹; 武传君; 张丁
2009-01-01
目的 研究在同一牙弓中牙齿相互作用条件下,0.56mm×0.71 mm(0.022英寸×0.028英寸)国产奥杰全程式托槽与日本OPA-K金属托槽在转矩控制方面是否有差异.方法 通过Typodont水浴实验,模拟临床矫治过程,测量结束弓丝为0.48 mm×0.64 mm(0.019英寸× 0.025英寸)SS方丝时使用两种品牌托槽的上颌5⊥5的唇舌向倾斜度,并通过数学编程计算转化为上颌5⊥5的转矩余隙角ψ,对其绝对值进行配对t检验.结果 结束弓丝为0.48 mm ×0.64 mm(0.019英寸×0.025英寸)SS方丝时,OPA-K金属托槽的转矩余隙角ψ的绝对值为(4.834±2.846)°,奥杰全程式金属托槽的转矩余隙角ψ的绝对值为(4.469±3.213)°,两种托槽间的差异无统计学意义(P=0.309).结论 0.56 mm×0.71 mm(0.022英寸× 0.028英寸)的OPA-K金属托槽和奥杰全程式托槽在转矩控制方面无差异,临床上使用这两种托槽均可达到满意的转矩控制.%Objective To compare the effect of two kinds of brackets (OPA-K and ORJ metal brackets)on torque con-trol when teeth are interacted in the same arch. Methods After the upper arch was aligned and leveled in Typodont study, the inclinations of upper teeth 5⊥5 were measured when 0.56 mm × 0.71 mm OPA-K metal brackets and 0.56 mm × 0.71 mm ORJ brackets were filled with 0.48 mm × 0.64 mm SS. The inclinatons of each tooth were transformed to the absolute values of the torque play angle ψ by computing program, and paired-t test was used. Results The two kinds of brackets had no statistical significance on torque control when the brackets were filled with 0.48 mm × 0.64 mm SS;the absolute values of the angle ψ in 0.56 mm × 0.71 mm OPA-K metal brackets and 0.56 mm × 0.71 mm ORJ metal brackets were 4.834°±2.846° and 4.469°±3.213° respectively. There was no statistical significance between the two kinds of brackets. Conclusion There is no difference between 0.56 mm × 0.71 mm OPA-K metal bracket and 0.56 mm × 0.71 mm ORJ
A structurally decoupled mechanism for measuring wrist torque in three degrees of freedom
Pan, Lizhi; Yang, Zhen; Zhang, Dingguo
2015-10-01
The wrist joint is a critical part of the human body for movement. Measuring the torque of the wrist with three degrees of freedom (DOFs) is important in some fields, including rehabilitation, biomechanics, ergonomics, and human-machine interfacing. However, the particular structure of the wrist joint makes it difficult to measure the torque in all three directions simultaneously. This work develops a structurally decoupled instrument for measuring and improving the measurement accuracy of 3-DOF wrist torque during isometric contraction. Three single-axis torque sensors were embedded in a customized mechanical structure. The dimensions and components of the instrument were designed based on requirement of manufacturability. A prototype of the instrument was machined, assembled, integrated, and tested. The results show that the structurally decoupled mechanism is feasible for acquiring wrist torque data in three directions either independently or simultaneously. As a case study, we use the device to measure wrist torques concurrently with electromyography signal acquisition in preparation for simultaneous and proportional myoelectric control of prostheses.
Sethi, P.; Krishnia, S.; Li, S. H.; Lew, W. S.
2017-03-01
We investigate and quantify spin-orbit torque (SOT) strength by current induced effective in-plane magnetic fields and spin Hall angle (SHA) using AC harmonic Hall voltage measurements techniques on Ta/Pt/Co/Pt/Co/Ta thin film structures. The proposed Co/Pt thin film double stack gives property enhancement on thermal stability and perpendicular magnetization anisotropy strength over the single stack Pt/Co/Ta. In the proposed Co/Pt double stack we observed that increasing the Ta capping thickness to three times enhances the SHA in similar order, consistent with larger spin injection efficiency. Doubling the Pt spacer layer thickness reduces the SHA by nearly 1.4 times, due to partial cancellation of SOT by bottom layer Pt, negating the increase from the top Co/Pt interface. The in-plane current threshold for magnetization switching is lower with the increase of the SHA.
Esquivel-Sirvent, Raul; Schatz, George
2014-03-01
The theory of generalized van der Waals forces by Lifshtz when applied to optically anisotropic media predicts the existence of a torque. In this work we present a theoretical calculation of the van der Waals torque for two systems. First we consider two isotropic parallel plates where the anisotropy is induced using an external magnetic field. The anisotropy will in turn induce a torque. As a case study we consider III-IV semiconductors such as InSb that can support magneto plasmons. The calculations of the torque are done in the Voigt configuration, that occurs when the magnetic field is parallel to the surface of the slabs. The change in the dielectric function as the magnetic field increases has the effect of decreasing the van der Waals force and increasing the torque. Thus, the external magnetic field is used to tune both the force and torque. The second example we present is the use of the torque in the non retarded regime to align arrays of nano particle slabs. The torque is calculated within Barash and Ginzburg formalism in the nonretarded limit, and is quantified by the introduction of a Hamaker torque constant. Calculations are conducted between anisotropic slabs of materials including BaTiO3 and arrays of Ag nano particles. Depending on the shape and arrangement of the Ag nano particles the effective dielectric function of the array can be tuned as to make it more or less anisotropic. We show how this torque can be used in self assembly of arrays of nano particles. ref. R. Esquivel-Sirvent, G. C. Schatz, Phys. Chem C, 117, 5492 (2013). partial support from DGAPA-UNAM.
Controller-independent bidirectional quantum direct communication
Mohapatra, Amit Kumar; Balakrishnan, S.
2017-06-01
Recently, Chang et al. (Quantum Inf Process 14:3515-3522, 2015) proposed a controlled bidirectional quantum direct communication protocol using Bell states. In this work, the significance of Bell states, which are being used as initial states in Chang et al. protocol, is elucidated. The possibility of preparing initial state based on the secret message of the communicants is explored. In doing so, the controller-independent bidirectional quantum direct communication protocol has evolved naturally. It is shown that any communicant cannot read the secret message without knowing the initial states generated by the other communicant. Further, intercept-and-resend attack and information leakage can be avoided. The proposed protocol is like a conversion between two persons without the help of any third person with high-level security.
Modelling of a Magnetostrictive Torque Sensor
Tsiantos Vasilios
2016-01-01
Full Text Available Existing magnetostrictive torque sensor designs typically measure the rotation of the saturation magnetization under an applied torque and their theoretical treatment revolves around the minimization of the free energy equation adapted according to the assumptions considered valid in each design. In the torque measurement design discussed in this paper, Ni-rich NiFe films have been electrodeposited on cylindrical austenitic steel rods. Contrary to existing designs, the excitation field is applied along the axial direction and is low enough to ensure that the resulting magnetization along the same direction remains in the linear region of the M(H characteristic. Assuming homogeneous magnetization, positive magnetostriction constant λ, negligible hysteresis and demagnetizing fields, torque T may be expressed in terms of an effective uniaxial anisotropy constant Ku around 45° to the axial direction. It is shown, that for the proposed arrangement, the resulting M is the linear superposition of the effect of a torque-induced effective field and the excitation field, the applied field accounts for the vertical offset of the magnetization response and the applied torque increases the slope of the M(H characteristic.
邹治锐; 陈世元
2013-01-01
造成电励磁双凸极电机转矩脉动的原因有很多,通过适当的控制策略可以优化某些因素从而改善转矩脉动.从控制策略方面总结了近年来优化转矩脉动的研究成果,介绍了几种有效的控制方法,大体思路可以从改善绕组相电流(包括稳定相电流、消去谐波电流、电流矢量分解等)、优化开关角度弥补换相电流缺陷以及优化输出转矩控制等方面来减小转矩脉动.%There are many factors cause torque ripple of doubly salient electro - magnetic motor. Appropriate control strategies can optimize some factors to improve torque ripple. The research achievements about torque ripple optimization from the control strategy in recent years were summarized, and some feasible methods was introduced to reduce torque ripple. The general ideas involve improving the winding current (including stable phase current, elimination harmonic current, current vector decomposition,etc.),optimizing the switch angle that made up in phase current defect and optimized output torque control,etc.
Kong, Xiangxi; Zhang, Xueliang; Chen, Xiaozhe; Wen, Bangchun; Wang, Bo
2016-05-01
In this paper, phase and speed synchronization control of four eccentric rotors (ERs) driven by induction motors in a linear vibratory feeder with unknown time-varying load torques is studied. Firstly, the electromechanical coupling model of the linear vibratory feeder is established by associating induction motor's model with the dynamic model of the system, which is a typical under actuated model. According to the characteristics of the linear vibratory feeder, the complex control problem of the under actuated electromechanical coupling model converts to phase and speed synchronization control of four ERs. In order to keep the four ERs operating synchronously with zero phase differences, phase and speed synchronization controllers are designed by employing adaptive sliding mode control (ASMC) algorithm via a modified master-slave structure. The stability of the controllers is proved by Lyapunov stability theorem. The proposed controllers are verified by simulation via Matlab/Simulink program and compared with the conventional sliding mode control (SMC) algorithm. The results show the proposed controllers can reject the time-varying load torques effectively and four ERs can operate synchronously with zero phase differences. Moreover, the control performance is better than the conventional SMC algorithm and the chattering phenomenon is attenuated. Furthermore, the effects of reference speed and parametric perturbations are discussed to show the strong robustness of the proposed controllers. Finally, experiments on a simple vibratory test bench are operated by using the proposed controllers and without control, respectively, to validate the effectiveness of the proposed controllers further.
大输出微控制力矩陀螺的设计%Design of a Micro Control Moment Gyroscope with a Large Torque Output
常洪龙; 白滨; 焦文龙; 谢建兵; 秦子明; 苑伟政
2011-01-01
为了提高微控制力矩陀螺的输出力矩,提出了一种微型控制力矩陀螺的设计方案.所设计的微型控制力矩陀螺用角振动代替了传统控制力矩陀螺的转动,由转子角振动系统及框架角振动系统组成,实现了基于科氏效应的控制力矩输出.通过框架角振动系统的电极位置居中设置及在玻璃上挖槽的设计,避免了静电吸合现象.四个完全相同的微型控制力矩陀螺构成一个阵列,每两个微型控制力矩陀螺的电压相位依次相差90°,即可消除寄生控制力矩并稳定力矩输出.所设计的微型控制力矩陀螺四单元阵列的力矩输出可达5.12×lO-6 Nm.最后,设计了微型控制力矩陀螺两层可动结构的工艺流程,所设计的工艺流程尽管具有一定的复杂性和难度,但均采用了当前一些比较成熟的工艺步骤,具有一定的可行性,有望在微型航天器的姿态控制上得到应用.%A novel micro control moment gyroscope( MCMG)with a large torque output is presented. In contrast with the traditional CMG,MCMG uses the angular vibration instead of angular rotation. The MCMG outputs the torque through a coupling of rotor angular vibration and gimbal angular vibration based on the Coriolis Effect. Through locating the electrodes in the centre of the MCMG and etching a trench in the glass wafer,the electrostatic pull-in effect is largely alleviated and the driving voltage is decreased. An array configuration using four MCMGs as an element stabilizes the overall torque output at the array level and eliminates the unwanted torques. The voltage phase differences between every two MCMGs are 90° in sequence. The torque output of the MCMG array is about 5. 12× 10-6 Nm. At last the process flow for this MCMG and possible applications in attitude control of a microsatellite is discussed.
Surface Roughness Effects on Vortex Torque of Air Supported Gyroscope
LIANG Yingchun; LIU Jingshi; SUN Yazhou; LU Lihua
2011-01-01
In order to improve the drift precision of air supported gyroscope, effects of surface roughness magnitude and direction on vortex torque of air supported gyroscope are studied. Based on Christensen's rough surface stochastic model and consistency transformation method, Reynolds equation of air supported gyroscope containing surface roughness information is established.Also effects of mathematical models of main machining errors on vortex torque are established. By using finite element method,the Reynolds equation is solved numerically and the vortex torque in the presence of machining errors and surface roughness is calculated. The results show that surface roughness of slit has a significant effect on vortex torque. Transverse surface roughness makes vortex torque greater, while longitudinal surface roughness makes vortex torque smaller. The maximal difference approaches 11.4％ during the range analyzed in this article. However surface roughness of journal influences vortex torque insignificantly. The research is of great significance for designing and manufacturing air supported gyroscope and predicting its performance.
Efficient Controlled Quantum Secure Direct Communication Protocols
Patwardhan, Siddharth; Moulick, Subhayan Roy; Panigrahi, Prasanta K.
2016-07-01
We study controlled quantum secure direct communication (CQSDC), a cryptographic scheme where a sender can send a secret bit-string to an intended recipient, without any secure classical channel, who can obtain the complete bit-string only with the permission of a controller. We report an efficient protocol to realize CQSDC using Cluster state and then go on to construct a (2-3)-CQSDC using Brown state, where a coalition of any two of the three controllers is required to retrieve the complete message. We argue both protocols to be unconditionally secure and analyze the efficiency of the protocols to show it to outperform the existing schemes while maintaining the same security specifications.
Peterson, D. H.
1981-01-01
Torque-wrench extension makes it easy to install and remove fasteners that are beyond reach of typical wrenches or are located in narrow spaces that prevent full travel of wrench handle. At same time, tool reads applied torque accurately. Wrench drive system, for torques up to 125 inch-pounds, uses 2 standard drive-socket extensions in aluminum frame. Extensions are connected to bevel gear that turns another bevel gear. Gears produce 1:1 turn ratio through 90 degree translation of axis of rotation. Output bevel has short extension that is used to attach 1/4-inch drive socket.
Exhaust powered drive shaft torque enhancer
Koch, A.B.
1986-09-30
This patent describes a power producing combination including an internal combustion engine and a mounting frame therefor, and power transmission means including rotating drive shaft means connected to the engine. The improvement described here is a drive shaft torque enhancing device, the device comprising: a multiplicity of blades secured to the drive shaft, equally spaced therearound, each generally lying in a plane containing the axis of the drive shaft; torque enhancer feed duct means for selectively directing a stream of exhaust gases from the engine to impact against the blades to impart torque to the drive shaft; and wherein the power producing combination is used in a vehicle, the vehicle having braking means including a brake pedal; and the power producing combination further comprising torque enhancer disengagement means responsive to motion of the brake pedal.
张炳义; 刘博年; 冯桂宏; 丁宏龙
2016-01-01
传统油田修井机采用柴油机或异步电机驱动.柴油机驱动系统的工作效率低、能耗大、污染高.异步电机和减速箱组成的驱动系统的功率因数低、系统维护复杂、噪声大.永磁电机直驱系统具有结构简单,高效节能,系统维护简单,噪声低等优点,可以解决传统柴油机以及异步电机存在的问题.该系统还具有易于控制,运行稳定的优势.通过单星形与双串星形双绕组变换的方法实现电机的宽恒功率调速.采用特殊表贴式转子结构可以削弱电机转矩脉动.控制上采用闭环矢量控制来实现电机的平稳运行以及带载悬停等功能.%The traditional oil field workover adopts a diesel engine or asynchronous motor as the drive.The diesel engine driving system has low efficiency,high energy consumption and high pol-lution.The drive system of the induction motor with the gearbox has low power factor,system maintenance is complex and the noise is large.Permanent magnetic motor direct drive system has the advantages of simple structure,high efficiency and energy saving,system maintenance is sim-ple and the noise is low.Permanent magnetic motor direct drive system can solve the problem of traditional diesel engine and asynchronous machine.At the same time,the system also has the ad-vantages of easy control and stable operation.The wide range of constant power expansion of the motor is realized by using the transformation of single star winding and double star winding .The torque ripple of the motor can be reduced by using a special form of surface mounted rotor struc-ture.The closed-loop vector control is adopted to realize the stable running of the motor and the function of cease with load.
Environmental controls: Market incentives v. direct regulation
Kosobud, R.F.; Atallah, D.S. [Univ. of Illinois, Chicago, IL (United States)
1996-12-31
Cap-and-trade environmental markets, where the commodities are tradable pollution rights, are being introduced in several closely watched applications as a potentially more cost-effective way of cleaning up the environment than direct or command-and-control (CAC) regulation. In this study, we examine the evidence on control cost savings provided by price and transactions data from the first few years of activity in two markets designed to reduce atmospheric pollution. Some observers of both markets have argued that prices for tradable permits lower than expected, and transactions fewer than expected, are evidence that the markets are not achieving the hoped for savings. It was found, on the contrary, that observed prices point toward more flexible and improved pollution control choices and that the number of transactions has been steadily increasing as market incentives are incorporated into enterprise decisions. These new markets during their first few years are generating, according to our estimates, control cost savings in the neighborhood of one to two billion dollars annually. However, there is evidence that the markets have not yet reached their full potential. In the course of this study, several obstacles to market performance were found that are worthy of attention by policy makers. 13 refs., 4 figs., 1 tab.
Dimensionality of joint torques and muscle patterns for reaching
Marta eRusso
2014-03-01
Full Text Available Muscle activities underlying many motor behaviors can be generated by a small number of basic activation patterns with specific features shared across movement conditions. Such low-dimensionality suggests that the central nervous system (CNS relies on a modular organization to simplify control. However, the relationship between the dimensionality of muscle patterns and that of joint torques is not fixed, because of redundancy and non-linearity in mapping the former into the latter, and needs to be investigated. We compared the torques acting at four arm joints during fast reaching movements in different directions in the frontal and sagittal planes and the underlying muscle patterns. The dimensionality of the non-gravitational components of torques and muscle patterns in the spatial, temporal, and spatiotemporal domains was estimated by multidimensional decomposition techniques. The spatial organization of torques was captured by two or three generators, indicating that not all the available coordination patterns are employed by the CNS. A single temporal generator with a biphasic profile was identified, generalizing previous observations on a single plane. The number of spatiotemporal generators was equal to the product of the spatial and temporal dimensionalities and their organization was essentially synchronous. Muscle pattern dimensionalities were higher than torques dimensionalities but also higher than the minimum imposed by the inherent non-negativity of muscle activations. The spatiotemporal dimensionality of the muscle patterns was lower than the product of their spatial and temporal dimensionality, indicating the existence of specific asynchronous coordination patterns. Thus, the larger dimensionalities of the muscle patterns may be required for CNS to overcome the non-linearities of the musculoskeletal system and to flexibly generate endpoint trajectories with simple kinematic features using a limited number of building blocks.
Fundamental limits of optical force and torque
Rahimzadegan, A.; Alaee, R.; Fernandez-Corbaton, I.; Rockstuhl, C.
2017-01-01
Optical force and torque provide unprecedented control on the spatial motion of small particles. A valid scientific question, that has many practical implications, concerns the existence of fundamental upper bounds for the achievable force and torque exerted by a plane wave illumination with a given intensity. Here, while studying isotropic particles, we show that different light-matter interaction channels contribute to the exerted force and torque, and analytically derive upper bounds for each of the contributions. Specific examples for particles that achieve those upper bounds are provided. We study how and to which extent different contributions can add up to result in the maximum optical force and torque. Our insights are important for applications ranging from molecular sorting, particle manipulation, and nanorobotics up to ambitious projects such as laser-propelled spaceships.
H∞ controller design for a 4-meter direct-drive azimuth axis
Chen, Li-Yan; Zhang, Zhen-Chao; Song, Xiao-Li; Wang, Da-Xing
2015-11-01
To pursue a higher imaging resolution for exploring more details in the information conveyed by the Universe, the next generation of optical telescopes based on a direct drive widely employ the extremely large aperture structure, which also introduces more disturbances and uncertain factors to the control system. Facing this new challenge, the PID control method in main-axis control systems of traditional astronomical telescopes cannot suffice for the requirement of the tracking precision and disturbance sensitivity in angular velocity. To overcome this shortcoming, we establish a dynamic model and propose an H∞ controller for a 4-meter azimuth direct drive control system that consists of a revolving platform (azimuth axis), a three-phase torque motor, a motor drive, an encoder, a data acquisition card and a small computers. Simulations are carried out to analyze the model and guide the real experiments. Experimental results show that the proposed H∞ controller reduces the tracking error by a maximum of 80.69% (average 57.8%) and the disturbance sensitivity by a maximum of 82.3% (average 50.96%) compared with the traditional tuned PI controller; furthermore, the order of the model describing the proposed controller can be reduced to three, thus its feasibility in real systems is guaranteed.
谢慕君; 步伟明; 冯敬芳; 王志乾
2013-01-01
针对电励磁同步电动机负载变化易失步的问题，通过对转矩角特性分析，提出了一种基于转矩角截止负反馈的控制策略。阐述了利用转矩角控制防止失步的原理，建立了基于同步电动机磁链观测的转矩角数学模型，并设计了转矩角外环、励磁电流内环的双闭环控制系统。仿真结果表明，该控制策略与常规控制相比，适应负载变化的能力显著提高，有效抑制了电机的失步，为电机的稳定控制开辟了新途径。%Aiming at the problem that the electrical synchronous excited motor will be out of step with the load changes, this paper raised a control strategy based on torque-angle cut-off feedback via the analysis of torque-angle characteristics. Discussion was made to the principle using torque-angle control to prevent out-of-step. The mathematical model of torque-angle was constructed based on the flux linkage observation of synchronous motors and the double closed-loop control system for the outer loop adopting torque-angle and the inner loop adopting field current were designed. The simulation results show that compared with conventional control, this control strategy obviously met the requirements of load changes, effectively restraining out-of-step of motors, which opens up a new way for stable control of motors.
Bevel gear driver and method having torque limit selection
Cook, Joseph S., Jr. (Inventor)
1994-01-01
This invention comprises a torque drive mechanism utilizing axially translatable, mutually engageable transmission members having mating crown gears, driven and driving members with a three-element drive train being biased together by resilient means or by a fluid actuator system, the apparatus being operable to transmit a precisely controlled degree of torque to a driven member. The apparatus is applicable for use in hand tools and as a replacement for impact torque drivers, torque wrenches, motorized screw drivers, or the like, wherein the applied torque must be precisely controlled or limited. The bevel torque drive includes a drive gear which is axially displaceable and rotatable within cylindrical driver housing, a rotatable intermediate gear, and an output gear. Key rotationally secures displaceable gear with respect to input shaft but permits axial movement therebetween. A thrust bearing is preferably connected to the lower end of shaft for support to reduce play and friction between shaft and a transmission joint disc during rotation of the gear train. Coaxially mounted coiled spring is footed against displaceable gear for biasing the displaceable gear toward and into engagement with the intermediate gear for driving intermediate gear and output gear. Torque control is achieved by the use of straight or spiral beveled gears which are of configurations adapted to withdraw from mutual engagement upon the torque exceeding a predetermined limit. The novel, advantageous features of the invention include the configuration of the mating, crown gear sets and the axially translatable, slidable drive gear. The mechanism is capable of transmitting a high degree of torque within a narrow, compact transmission housing. The compact size and narrow, elongated configuration of the housing is particularly applicable for use in hand tools and in multiple torque driver mechanisms in which it is necessary to drive multiple fasteners which are located in close proximity. Prior
Prattico, Flavio; Yamamoto, Shin-ichiroh
2014-01-01
In this paper we give a new control model based on the so called computed-torque method for the control of a 2 degrees of freedom orthosis for the rehabilitation of the lower limb, the AIRGAIT exoskeleton's leg orthosis. The actuation of the AIRGAIT is made through self-made pneumatic muscles. For this reason this work starts with the static and dynamic characterization of our pneumatic muscles. The followed approach is based on the analytical description of the system. For this, we describe the pneumatic muscles behaviour with an easy-invertible polynomial fit function in order to model its non-linear trend. We give a geometrical model of the mechanical system to compute the length between the attachments of the pneumatic muscles to the structure for every angles assumed by the two joints. We evaluate through Newton-Euler equation the couples at the joints for each values of the angles. At last we show some validation tests in order to characterize the functioning of the proposed control model on the actuati...
Ironless armature torque motor
Fisher, R. L.
1972-01-01
Four iron-less armature torque motors, four Hall device position sensor assemblies, and two test fixtures were fabricated. The design approach utilized samarium cobalt permanent magnets, a large airgap, and a three-phase winding in a stationary ironless armature. Hall devices were employed to sense rotor position. An ironless armature torque motor having an outer diameter of 4.25 inches was developed to produce a torque constant of 65 ounce-inches per ampere with a resistance of 20.5 ohms. The total weight, including structural elements, was 1.58 pounds. Test results indicated that all specifications were met except for generated voltage waveform. It is recommended that investigations be made concerning the generated voltage waveform to determine if it may be improved.
Chen, Jun; Ng, Jack; Ding, Kun; Fung, Kin Hung; Lin, Zhifang; Chan, C T
2014-09-17
Light carries angular momentum, and as such it can exert torques on material objects. Applications of these opto-mechanical effects were limited initially due to their smallness in magnitude, but later becomes powerful and versatile after the invention of laser. Novel and practical approaches for harvesting light for particle rotation have since been demonstrated, where the structure is always subjected to a positive optical torque along a certain axis if the incident angular momentum has a positive projection on the same axis. We report here an interesting phenomenon of "negative optical torque", meaning that incoming photons carrying angular momentum rotate an object in the opposite sense. Surprisingly this can be realized quite straightforwardly in simple planar structures. Field retardation is a necessary condition and discrete rotational symmetry of material object plays an important role. The optimal conditions are explored and explained.
Robust spin transfer torque in antiferromagnetic tunnel junctions
Saidaoui, Hamed Ben Mohamed
2017-04-18
We theoretically study the current-induced spin torque in antiferromagnetic tunnel junctions, composed of two semi-infinite antiferromagnetic layers separated by a tunnel barrier, in both clean and disordered regimes. We find that the torque enabling electrical manipulation of the Néel antiferromagnetic order parameter is out of plane, ∼n×p, while the torque competing with the antiferromagnetic exchange is in plane, ∼n×(p×n). Here, p and n are the Néel order parameter direction of the reference and free layers, respectively. Their bias dependence shows behavior similar to that in ferromagnetic tunnel junctions, the in-plane torque being mostly linear in bias, while the out-of-plane torque is quadratic. Most importantly, we find that the spin transfer torque in antiferromagnetic tunnel junctions is much more robust against disorder than that in antiferromagnetic metallic spin valves due to the tunneling nature of spin transport.
Simulation analyzing of torque-ripple minimization for switched reluctance motor
无
2001-01-01
Discusses the inevitability of torque-ripple of switchedreluctance motor (SRM) for its double saliency construction and switch power supply, and the minimization of torque-ripple, under traditional current chopping control mode, and presents a varying current amplitude chopping control method with a linear control model of varying current amplitude chopping shown, and the simulation of torque profiles under two kinds of current chopping control modes to demonstrate the validity of decreasing torque-ripple.
王德伟; 青春; 张文; 朱博
2015-01-01
The paper introduces the constituent parts and the working principle of the locking structure of the threaded -coupling electrical connectors locked by oblique teeth , and summarizes the mating and unmating torque requirement of the connectors , gives the calculational method of the maximum engagement and the minimum disen-gagement torque on the basis of the force analysis of the product .The paper also analyzes and summarizes the rela-tive factors of the coupling torque , and makes corresponding control measures in order to control the magnitude of the coupling torque effectively .%文章介绍了斜齿端面锁紧螺纹电连接器的锁紧结构组成、工作原理以及电连接器插合、分离时的扭矩要求。对斜齿端面锁紧螺纹电连接器进行了受力分析，提出了产品最大连接扭矩、最小分离扭矩的计算方法。分析归纳了影响扭矩大小的相关因素，制定了相应的控制措施，从而达到有效控制产品扭矩大小的目的。
杨淑英; 占琦; 张兴; 郭磊磊; 周岩峰
2014-01-01
The permanent magnet synchronous motor (PMSM) used in wind turbine and electric vehicle situations usually has to directly track the torque command issued by the main control system.As a matter of fact,however,no torque test components such as a torque sensor is available in an actual system.So the exact acquisition of the observed torque is of utmost importance for the torque control system.To enhance the torque observer performance,this paper proposes a real-time stator flux linkage observation method based on a minimum extended flux linkage observer,through which the stator flux linkage and the electrical torque are calculated.The proposed stator flux linkage observer is not only free from the flaws of the traditional pure integral strategy,such as saturation,phase shift,amplitude deviation,and so on,but also,as a pure integral strategy,is robust for parameter deviation, namely, the precision of the observed torque is basically unaffected by the direct-and quadrature-axis inductance and the rotor flux linkage.Simulations and experiments on an 11kW PMSM have validated the performance of the proposed method.%用于风力发电和电动汽车等特殊应用场合中的永磁同步电机(PMSM)驱动器通常需要直接跟踪主控系统下发的转矩指令，而实际系统中通常不安装扭矩仪等转矩检测部件，因此，电磁转矩的准确获取对高精度转矩闭环至关重要。文中提出了一种基于最小阶扩展磁链观测器的实时定子磁链观测方案，并在此基础上完成电磁转矩的观测计算。该定子磁链观测方案不仅可以避免传统方案造成的积分饱和、相位或幅值偏差等不利影响，而且该观测方案具有较强的参数鲁棒性，其转矩观测计算精度基本不受PMSM交、直轴电感以及转子磁链的影响。11 kW的 PMSM仿真与实验验证了该方案的可行性和有效性。
赵峰; 罗禹贡; 张娜; 李克强
2014-01-01
In view of the problem of the increase of transient fuel consumption in hard acceleration of elec-tric hybrid vehicle ( HEV) caused by mixture enrichment, a dynamic coordinated control scheme for the process of engine torque abrupt change of HEV based on torque dynamic compensation in this paper. An engine torque control strategy is designed based on torque changing rate limitation to avoid the increase of transient fuel consumption dur-ing the sudden change of engine torque, while ensuring the power performance of vehicle in acceleration process. The results of real vehicle test indicate that the dynamic coordinated control scheme proposed not only reduce the transient fuel consumption of engine during acceleration but also enhance the power performance of vehicle.%针对混合动力汽车急加速时由于混合气瞬间加浓引起动态油耗增加的问题，本文中提出了基于转矩动态补偿的混合动力汽车发动机转矩突变过程动态协调控制方法。设计了基于转矩变化率限制的发动机转矩控制策略，避免了发动机转矩突变过程中动态油耗的增加，同时保证了加速过程中整车的动力性。实车试验结果表明，提出的动态协调控制方法不仅降低了加速过程中发动机的动态油耗，同时提高了整车动力性。
胡超超; 王旭芳; 陈志颖; 张文华; 江海兵
2015-01-01
The impact wrench with four synchronously installed and uninstalled screws and controlled torques consists of a im-pact wrench and an adapter, mainly used to synchronously install and uninstall four screws that are evenly distributed on the same circumference. The adapter mainly consists of a hull, gears, a re-ducing device, a torque regulation and overload protection device, and external hexagon wrenches. The gears are used to drive torques and move. The reducing device is used to change the cir-cumferences and diameters of the four external hexagon wrench-es. The torque regulation and overload protection device is used to adjust the maximum torques of the hexagon wrenches and pre-vent torque overload in the installation and uninstallation. The adapter is efficient in installation with simple structures, control-lable torques and convenient operation, which can improve the quality and effectiveness of installation, and reduce labor intensi-ty, so it has broad application value and market prospect.%四颗螺钉同步装卸力矩可控式气动扳手由气动扳手和转换接头组成，其主要用于同步装配和拆卸均布在同一圆周上的四颗螺钉，转换接头主要由壳体、齿轮传动装置、变径装置、力矩调节和过载保护装置、外六角扳子组成；齿轮传动装置用于传动力矩和运动，变径装置用于变换4个外六角扳子的圆周直径，力矩调节和过载保护装置用于调节扳子的最大力矩和防止装配和拆卸中的力矩过载；该接头装配效率高、结构简单、力矩可控、操作方便，可提高装配质量和装配效率，降低劳动强度，具有广泛应用价值和市场前景。
张晓光; 孙力; 赵克
2012-01-01
为了减小负载转矩扰动对永磁同步电机（permanentmagnet synchronous motor,PMSM）控制系统的影响,提高系统抗扰能力,提出一种以转速和负载转矩为观测对象的扩展滑模观测器,以实际转速与观测转速之差构成滑模面,负载转矩观测结果由负载转矩实际值和经过滤波后的抖振信号组成,当滑模运动发生后转矩观测误差渐进收敛到零。设计了基于指数趋近律的PMSM滑模控制（sliding-modevariable structure control,SMC）系统,将观测的负载转矩进行前馈补偿,以克服负载时变对控制性能的影响。实验结果表明,该观测器可准确地观测负载转矩,采用的前馈补偿方案对系统负载扰动有较强的鲁棒性,并且SMC固有抖振现象得到了有效抑制。%An extended sliding-mode observer of the load torque was proposed,of which the state variables were speed and load torque,in order to decrease influence of varying load torque in a permanent magnet synchronous motor（PMSM） control system.Errors between the real and the observed speed were selected as a sliding-mode hyper plane,and the observed load torque was composed of a real load torque and the filtered chattering signal.The observation error converged to zero when sliding mode occurred.A sliding-mode variable structure control（SMC）.system of PMSM was designed based on the exponent reaching law,in which the observed load torque was used for feed-forward compensation.Experimental results show that the novel sliding-mode observer can estimate the load torque precisely,and the designed controller can enhance system robustness and suppress the intrinsic chattering of SMC.
张相军; 陈伯时
2001-01-01
This paper introduces four PWM modes used in the sensorless brushless DC motor control system, analyzes their different influences on the commutation torque ripple in detail, and selects the best PWM mode in four given types to reduce commutation torque ripple of Brushless OC(BLDC) motors. Simulation and experimental results show that the selection is correct and practical.
COMMUTATION TIME ESTIMATOR FOR PM BLDC MOTOR TORQUE SIGNATURE ENHANCEMENT
WAEL A. SALAH
2014-12-01
Full Text Available This paper presents the development of the commutation time estimator (CTE for PM BLDC motor drives. The proposed scheme is aimed to enhance motor output torque by minimizing the generated torque ripples. The torque ripples originating from commutation instances cause spikes and dips in the motor output torque. The motor output torque could be enhanced by mitigating the phase current mismatch rate during phase current commutation period. This rate could be almost matched by introducing the commutation time estimator (CTE in order to control the rate of the energized phase current to be matched with the de-energized phase rate. Results obtained have validated and verified the proposed CTE effectiveness with a 50% average reduction of the generated torque ripples in PM BLDC motor.
The control technology research device of a large torque standard%超大扭矩标准装置及其力偶控制技术研究
倪守忠; 蒋晓波; 尚贤平; 王鹏; 李海根
2015-01-01
This paper describes a large torque standard equipment, which by the servo motor, gear pump, and a swinging oil cylinder and the auxiliary balance cylinder torque drive, the measuring lever and four groups of special measuring force module precision torque measurement, the realization of the rapid precision torque control, and effectively reduce the bearing support reaction force caused by the measurement uncertainty.%本文介绍了一种超大扭矩标准装置, 该装置由伺服电机、 齿轮泵、 摆动油缸及辅助平衡油缸进行力矩驱动, 由测量杠杆及四组专用测力模块进行扭矩精密测量, 实现了扭矩快速精密控制, 并有效减小轴承支反力引起的测量不确定度.
Effects of Paradoxical and Self-Control Directives in Counseling.
Lopez, Frederick G.; Wambach, Cathrine A.
1982-01-01
Subjects (N=32) with recurring procrastination problems were assigned to either of two directive interview conditions (paradoxical or self-control) or to a no-interview control condition. Results indicated both directive groups exhibited generally greater improvement over time than controls and that opposing forms of direction promoted different…
Kish, J.
1991-01-01
Geared drive train transmits torque from input shaft in equal parts along two paths in parallel, then combines torques in single output shaft. Scheme reduces load on teeth of meshing gears while furnishing redundancy to protect against failures. Such splitting and recombination of torques common in design of turbine engines.
Lee, Soo Han
1988-01-01
The efficiency and positional accuracy of a lightweight flexible manipulator are limited by its flexural vibrations, which last after a gross motion is completed. The vibration delays subsequent operations. In the proposed work, the vibration is suppressed by inertial force of a small arm in addition to the joint actuators and passive damping treatment. The proposed approach is: (1) Dynamic modeling of a combined system, a large flexible manipulator and a small arm, (2) Determination of optimal sensor location and controller algorithm, and (3) Verification of the fitness of model and the performance of controller.
Influence of Control Structures and Load Parameters on Performance of a Pseudo Direct Drive
Mohammed Bouheraoua
2014-07-01
Full Text Available The paper describes an in-depth and systematic analysis of a pseudo direct drive permanent magnet machine in closed loop control. Due to the torque being transmitted from the high-speed rotor (HSR to the low-speed rotor (LSR, through a relatively low stiffness magnetic gear with non-linear characteristics, speed oscillations appear in the drive output with a conventional proportional integral (PI controller. Therefore two candidate controllers have been proposed as an alternative to the PI control and all controllers have been optimally tuned with a genetic algorithm against a defined criterion. Furthermore, closed loop models are established in the complex frequency domain to determine the system damping and the cause of the oscillations. Consequently, the best controller structure that improves the dynamic behaviour of the system in terms of speed tracking and disturbance rejection could be identified, based on the frequency domain analysis. Experimental results are presented to validate the analysis and the proposed control technique.
Self-induced torque in hyperbolic metamaterials.
Ginzburg, Pavel; Krasavin, Alexey V; Poddubny, Alexander N; Belov, Pavel A; Kivshar, Yuri S; Zayats, Anatoly V
2013-07-19
Optical forces constitute a fundamental phenomenon important in various fields of science, from astronomy to biology. Generally, intense external radiation sources are required to achieve measurable effects suitable for applications. Here we demonstrate that quantum emitters placed in a homogeneous anisotropic medium induce self-torques, aligning themselves in the well-defined direction determined by an anisotropy, in order to maximize their radiation efficiency. We develop a universal quantum-mechanical theory of self-induced torques acting on an emitter placed in a material environment. The theoretical framework is based on the radiation reaction approach utilizing the rigorous Langevin local quantization of electromagnetic excitations. We show more than 2 orders of magnitude enhancement of the self-torque by an anisotropic metamaterial with hyperbolic dispersion, having negative ratio of permittivity tensor components, in comparison with conventional anisotropic crystals with the highest naturally available anisotropy.
赵凯辉; 陈特放; 张昌凡; 何静; 黄刚
2014-01-01
To improve the performance of the torque precision for PMSM(Permanent Magnet Synchronous Motor)of railway vehicles, a novel sliding mode observer of active flux and a precise torque control method are proposed for a vector control system of PMSM. The concept of active flux is adopted and the mathematical model of Interior Permanent Magnet Synchro-nous Motor(IPMSM)has been established. The sliding mode observer of active flux is constructed in α-β stator coordinate frame, and it is observed active flux by applying sliding mode equivalent control methodology, then it realizes the real-time estimation of torque. The precise torque closed-loop control system is constituted combining with the torque command. The simulation results verify the feasibility and effectiveness of the method. The torque control precision of the PMSM can be improved, and the driving performance of railway PMSM vehicles is fulfilled and guaranteed. This method is not only applicable to IPMSM but to Surface-mounted Permanent Magnet Synchronous Motors(SPMSM)as well.%为了改善轨道交通永磁同步电动机转矩控制的性能，提出了一种改进的有效磁链滑模观测器，实现了永磁同步电动机的精确转矩闭环控制。采用有效磁链的概念，建立了基于有效磁链的内置式永磁同步电机数学模型；在α-β静止坐标系建立了有效磁链的滑模观测器，并基于滑模等值控制方法实现了有效磁链的观测，进而进行转矩的实时估算，以此和转矩给定值形成精确转矩闭环控制。通过仿真验证该方法的可行性和有效性。结果表明提高永磁同步电动机的转矩控制精度，改善了轨道永磁同步电动机控制系统的性能。该方法不仅适用于内置式永磁同步电机，而且适用于表贴式永磁同步电机。
Torque Characteristics of Saturated Permanent-Magnet Synchronous Motors
Takahashi, Akeshi; Kikuchi, Satoshi; Wakui, Shinichi; Mikami, Hiroyuki; Ide, Kazumasa; Shima, Kazuo
The evaluation of torque characteristics in a saturated magnetic field for permanent-magnet (PM) synchronous motors is presented. The torque saturation characteristics of non-salient and salient pole machines are investigated by finite element analysis and measurement. Thus, it is found that the torque saturation originates in the magnetic saturation in both the stator teeth, which are located on the leading position toward the direct axis, and in the stator back yoke, which is located on the lagging position toward the direct axis. This mechanism can also explain the reason for the significant torque saturation in the salient-pole machine; the higher inductance of the quadrature axis of the salient-pole machine causes a significant magnetic saturation in the stator back yoke. Therefore, less saliency or a wider back yoke can improve the torque saturation.
混合动力电动汽车转矩管理控制策略设计%Designing of Torque Control Strategy for Hybrid Electric Vehicle
庄怀天
2014-01-01
混合动力汽车的出现在一定程度上缓解了能源危机和环境问题。控制策略作为混合动力汽车的核心技术，对动力性和燃油经济性的实现起到至关重要的作用。主要研究模糊逻辑控制策略的制定及基于 Advisor 的仿真。提出了将总需求转矩和电池荷电状态划分为更多模糊子集以得到更细的模糊规则的方法。通过比较仿真结果验证了细分的模糊逻辑控制策略对提高动力性和燃油经济性的积极作用。%The emergence of hybrid vehicles,to a certain extent,ease the energy crisis and environmental problems. As the core technology of hybrid vehicles,control strategy plays a crucial role for the realization of the power performance and fuel e-conomy. The main content of the article is the fuzzy logic control strategy design and stimulations based on Advisor,presents that dividing the aggregate torque demand and the battery charged state into more fuzzy subset to pour more fine method of fuzz-y rules. The stimulant results verify the subdivision of the fuzzy logic control strategy is positive to improve power performance and fuel economy.
Manufacturing Research: Self-Directed Control
1991-01-01
Knudsen Cell over its entire operating range. A topic of continuing interest in PID controllers is the automatic tuning of the PID parameters that...PID map for the Knudsen Cells was explored using commercial automatic tuning PID controllers and software based tuning algorithms. For a complete state...decisions are made by a Hewlett-Packard HP 1000 computer. The HP 1000 sends its control signals to Barber-Colman PID controllers . We took advantage of
Hiroyuki NAKAMOTO; Kobayashi, Futoshi; Nobuaki IMAMURA; Shirasawa, Hidenori; Kojima, Fumio
2007-01-01
Various humanoid robots have been developed and multifunction robot hands which are able to attach those robots like human hand is needed. But a useful robot hand has not been depeveloped, because there are a lot of problems such as control method of many degrees of freedom and processing method of enormous sensor outputs. Realizing such robot hand, we have developed five-finger robot hand. In this paper, the detailed structure of developed robot hand is described. The robot hand we developed...
Creech, Angus; Maguire, A Eoghan
2014-01-01
We present here a computational fluid dynamics (CFD) simulation of Lillgrund offshore wind farm, which is located in the {\\O}resund Strait between Sweden and Denmark. The simulation combines a dynamic representation of wind turbines embedded within a Large-Eddy Simulation CFD solver, and uses hr-adaptive meshing to increase or decrease mesh resolution where required. This allows the resolution of both large scale flow structures around the wind farm, and local flow conditions at individual turbines; consequently, the response of each turbine to local conditions can be modelled, as well as the resulting evolution of the turbine wakes. This paper provides a detailed description of the turbine model which simulates interactions between the wind, turbine rotors, and turbine generators by calculating the forces on the rotor, the body forces on the air, and instantaneous power output. This model was used to investigate a selection of key wind speeds and directions, investigating cases where a row of turbines would ...
Heng NIAN; Yi-peng SONG
2015-01-01
This paper presents a multiple target implementation technique for a doubly fed induction generator (DFIG) under unbalanced and distorted grid voltage based on direct power control (DPC). Based on the mathematical model of DFIG under unbalanced and distorted voltage, the proportional and integral (PI) regulator is adopted to regulate the DFIG average active and reactive powers, while the vector PI (VPI) resonant regulator is used to achieve three alternative control targets: (1) balanced and sinusoidal stator current; (2) smooth instantaneous stator active and reactive powers; (3) smooth electromagnetic torque and instantaneous stator reactive power. The major advantage of the proposed control strategy over the conventional method is that neither negative and harmonic sequence decomposition of grid voltage nor complicated control reference calculation is required. The insensitivity of the proposed control strategy to DFIG parameter deviation is analyzed. Finally, the DFIG experimental system is developed to validate the availability of the proposed DPC strategy under unbalanced and distorted grid voltage.
Moody, Paul E.
1995-07-01
A high-torque quiet gear construction consists of an inner hub having a plurality of circumferentially spaced arms extending radially outwardly therefrom, and an outer ring member having a plurality of circumferentially spaced-teeth extending radially inwardly therefrom. The ring member further includes a plurality of gear formations on an outer surface thereof for intermeshing with other gears. The teeth of the ring member are received in spaced relation in corresponding spaces formed between adjacent arms of the hub. An elastomeric member is received in the space formed between the hub and the ring member to form a resilient correction between the arms of the hub and the teeth of the ring member. The side surfaces of the arms and the teeth extend generally parallel to each other and at least partially overlap in a longitudinal direction. The purpose of this configuration is to place the elastomeric member in compression when torque is applied to the hub. Since elastomeric material is relatively incompressible, the result is low shear loads on the adhesive bonds which hold the elastomeric member to both the hub and outer ring member.
郭行; 陈康; 孙力; 闫杰
2014-01-01
We establish the mathematical model of a motor-driven torque control simulator. Under the circumstance of passive load, we suppress the surplus torque by using the position-proportional control and angular-speed feed forward compensation. We design the control system that includes three loops:position-proportional control, angular speed feed forward compensation and closed-loop PID torque control. We then analyze the time domain and frequen-cy domain characteristics of the control system. The results and their analysis show preliminarily that the control sys-tem thus designed can significantly enhance the control precision of the motor-driven torque control simulator and expand the frequency band of its torque load to at least 25Hz.%仔细分析了电动负载模拟器的工作原理及多余力矩的产生机理，建立了电动负载模拟器的数学模型，在被动加载的情况下，提出了采用位置比例控制与角速度前馈补偿两种方法共同抑制多余力矩，设计了包含位置比例控制＋角速度前馈补偿＋力矩闭环控制的三回路控制系统，进一步提高了电动负载模拟器的控制精度并展宽了力矩加载频带，使得电动负载模拟器的加载频带提高到了25 Hz以上。
钱立军; 邱利宏; 辛付龙; 胡伟龙
2014-01-01
为克服传统比例-积分-微分（proportion integration differentiation，PID）以及模糊逻辑算法的缺陷、保障汽车经济性并改善乘员的乘坐舒适性，该文采用自适应模糊PID算法，建立了驾驶员模型。使用基于发动机输出转矩最优的能量管理控制策略，简述了驱动模式判别条件及转矩分配方法。提出1种“发动机调速+离合器模糊PID控制+发动机动态转矩查表+双电机转矩补偿控制”转矩协调控制方法，简述了模式切换步骤。在dSPACE实时仿真系统上对控制策略进行了硬件在环仿真。仿真结果表明，该控制策略在能量管理方面控制效果良好，动力部件的输出与控制策略完全吻合且平均车速误差下降37.1%。引入转矩协调之后，整车最大冲击度下降47.5%。该文的研究方法可以为制定复杂混合动力系统的控制策略提供参考。%This paper focuses on the control strategy of a plug-in 4-wheel-drive (4WD) hybrid electric vehicle (PHEV). To overcome the defects of the traditional proportion-integration-differentiation (PID) control method, an algorithm based on an adaptive fuzzy PID control method which provides better dynamic and static performances for the vehicle was adopted and a driver model was established using this algorithm. The input of the driver model was the difference between the cycle velocity and the actual output velocity of the vehicle. The output of the driver model was the required torque coefficient which reflects the driver’s intention and thus can be used to calculate the actual required torque of the driver. The PID parameters can be revised real-time according to the change of the cycle conditions, and the principle to choose theses parameters to ensure the stability of the controller was introduced as well. The domain of discourse for the inputs and outputs of the fuzzy PID controller and their membership functions were analyzed and parts of the fuzzy
Ghosh, Abhijit; Garello, Kevin; Avci, Can Onur; Gabureac, Mihai; Gambardella, Pietro
2017-01-01
Magnetic heterostructures that combine large spin-orbit torque efficiency, perpendicular magnetic anisotropy, and low resistivity are key to developing electrically controlled memory and logic devices. Here, we report on vector measurements of the current-induced spin-orbit torques and magnetization switching in perpendicularly magnetized Pd /Co /AlOx layers as a function of Pd thickness. We find sizable dampinglike (DL) and fieldlike (FL) torques, on the order of 1 mT per 107 A /cm2 , which have different thicknesses and magnetization angle dependencies. The analysis of the DL torque efficiency per unit current density and the electric field using drift-diffusion theory leads to an effective spin Hall angle and spin-diffusion length of Pd larger than 0.03 and 7 nm, respectively. The FL spin-orbit torque includes a significant interface contribution, is larger than estimated using drift-diffusion parameters, and, furthermore, is strongly enhanced upon rotation of the magnetization from the out-of-plane to the in-plane direction. Finally, taking advantage of the large spin-orbit torques in this system, we demonstrate bipolar magnetization switching of Pd /Co /AlOx layers with a similar current density to that used for Pt /Co layers with a comparable perpendicular magnetic anisotropy.
重复控制的开关磁阻电机转矩脉动抑制策略%Repetitive Control Based Torque Ripple Reduction Strategy for SRM
刘作军; 常硕; 董砚; 郑易
2013-01-01
针对开关磁阻电机在运行中的转矩脉动问题,提出了一种基于重复控制的开关磁阻电机转矩脉动抑制方法.在具有周期性扰动的控制系统中,重复控制把上一周期的偏差和当前的偏差叠加到被控对象进行控制,以达到高精度的控制效果.在此策略基础上,通过转子位置角估算和滞环电流控制,合理调节转矩大小,使电机转矩在运行中平稳过渡,从而达到抑制其转矩脉动的效果.仿真证实该方法能够有效地抑制开关磁阻电机的转矩脉动.%To reduce the torque ripple in switched reluctance motor,a strategy based on repetitive control was proposed.In the system with periodic disturbance,repetitive control can obtain high precision in the way of inputting the sum of error in the present period and the last period.Based on this strategy,the torque of SRM could be adjusted with rotator position and current hysteresis-band control to make the motor running smoothly.And high torque ripple control performance was obtained.Simulation and experiment prove the effect in reducing torque ripple of SRM.
Fundamental Limits of Optical Force and Torque
Rahimzadegan, Aso; Fernandez-Corbaton, Ivan; Rockstuhl, Carsten
2016-01-01
Optical force and torque provide unprecedented control on the spatial motion of small particles. A valid scientific question, that has many practical implications, concerns the existence of fundamental upper bounds for the achievable force and torque exerted by a plane wave illumination with a given intensity. Here, while studying isotropic particles, we show that different light-matter interaction channels contribute to the exerted force and torque and analytically derive upper bounds for each of the contributions. Specific examples for particles that achieve those upper bounds are provided. We study how and to which extent different contributions can be made to add up. Our insights are important for applications ranging from molecular sorting, particle manipulation, nanorobotics up to ambitious projects such as laser-propelled spaceships.
Directions for rf-controlled intelligent microvalve
Enderling, Stefan; Varadan, Vijay K.; Abbott, Derek
2001-03-01
In this paper, we consider the novel concept of a Radio Frequency (RF) controllable microvalve for different medical applications. Wireless communication via a Surface Acoustic Wave Identification-mark (SAW ID-tag) is used to control, drive and locate the microvalve inside the human body. The energy required for these functions is provided by RF pulses, which are transmitted to the valve and back by a reader/transmitter system outside of the body. These RF bursts are converted into Surface Acoustic Waves (SAWs), which propagate along the piezoelectric actuator material of the microvalve. These waves cause deflections, which are employed to open and close the microvalve. We identified five important areas of application of the microvalve in biomedicine: 1) fertility control; 2) artificial venous valves; 3) flow cytometry; 4) drug delivery and 5) DNA mapping.
Optimal control novel directions and applications
Aronna, Maria; Kalise, Dante
2017-01-01
Focusing on applications to science and engineering, this book presents the results of the ITN-FP7 SADCO network’s innovative research in optimization and control in the following interconnected topics: optimality conditions in optimal control, dynamic programming approaches to optimal feedback synthesis and reachability analysis, and computational developments in model predictive control. The novelty of the book resides in the fact that it has been developed by early career researchers, providing a good balance between clarity and scientific rigor. Each chapter features an introduction addressed to PhD students and some original contributions aimed at specialist researchers. Requiring only a graduate mathematical background, the book is self-contained. It will be of particular interest to graduate and advanced undergraduate students, industrial practitioners and to senior scientists wishing to update their knowledge.
Magnon-mediated Dzyaloshinskii-Moriya torque in homogeneous ferromagnets
Manchon, Aurelien
2014-12-01
In thin magnetic layers with structural inversion asymmetry and spin-orbit coupling, the Dzyaloshinskii-Moriya interaction arises at the interface. When a spin-wave current jm flows in a system with a homogeneous magnetization m, this interaction produces an effective fieldlike torque of the form TFLm×(z×jm) as well as a dampinglike torque, TDLm×[(z×jm)×m], the latter only in the presence of spin-wave relaxation (z is normal to the interface). These torques mediated by the magnon flow can reorient the time-averaged magnetization direction and display a number of similarities with the torques arising from the electron flow in a magnetic two-dimensional electron gas with Rashba spin-orbit coupling. This magnon-mediated spin-orbit torque can be efficient in the case of magnons driven by a thermal gradient.
Radiative torques on interstellar grains; 1, superthermal spinup
Draine, B T; Weingartner, Joseph C
1996-01-01
Irregular dust grains are subject to radiative torques when irradiated by interstellar starlight. It is shown how these radiative torques may be calculated using the discrete dipole approximation. Calculations are carried out for one irregular grain geometry, and three different grain sizes. It is shown that radiative torques can play an important dynamical role in spinup of interstellar dust grains, resulting in rotation rates which may exceed even those expected from H_2 formation on the grain surface. Because the radiative torque on an interstellar grain is determined by the overall grain geometry rather than merely the state of the grain surface, the resulting superthermal rotation is expected to be long-lived. By itself, long-lived superthermal rotation would permit grain alignment by normal paramagnetic dissipation on the "Davis-Greenstein" timescale. However, radiative torques arising from anisotropy of the starlight background can act directly to alter the grain alignment on much shorter timescales, a...
Direct Load Control by AC Frequency Modulation
Douglass, Philip James; You, Shi
2012-01-01
Fine-grained under frequency load shedding called “demand as a frequency controlled reserve“ (DFCR) has been shown to be a promising method of providingfrequency regulation service from distributed loads [1]. Micro-grids with a large portion of intermittent renewable generation will benefit great...
Torque-sharing strategy optimization of switched reluctance motor%开关磁阻电机转矩分配策略的优化
张炳力; 戚永武; 徐国胜
2012-01-01
The torque-sharing strategy is very popular in torque control of switched reluctance motor (SRM) in recent years, which pursues smooth phase commutation and torque ripple decrease by sharing the electromagnetic torque reasonably. However, due to the non-linear characteristic of SRM, the performance with both torque ripple decrease and high efficiency is difficult to achieve in entire speed range by means of fix-curved torque-sharing function(TSF). Therefore, based on the regular torque-sharing strategy, an optimized strategy is proposed to maximize,the torque/ampere ratio. This strategy aims to reduce the phase current by adjusting switch angles on line within limits of allowable torque error to guarantee the output torque. Simulation models of direct instantaneous torque control system with regular and optimized torque-sharing strategies are built respectively based on the software Matlab/Simulink. The simulation results show that the optimized strategy improves the efficiency of SRM on the basis of reasonable torque sharing.%转矩分配策略是近年来开关磁阻电机(SRM)转矩控制中比较流行的一种控制策略,旨在通过合理的分配电磁转矩,达到平稳换相、减小转矩脉动的目的.SRM的非线性特性使得固定形状的转矩分配函数(TSF)无法在整个转速范围内既能抑制脉动,也能保持高效率.文章提出了一种基于常规转矩分配策略的以转矩/安培比最大化为目标的优化方案,在允许的转矩误差范围内在线调整电机的开关角度,保证输出转矩的前提下降低绕组中通过的相电流.在Matlab/Simulink软件中分别建立了常规转矩分配方案和优化方案的直接瞬时转矩控制系统模型.比较分析仿真结果得出,优化后的转矩分配方案在保证合理分配电磁转矩的同时,提高了SRM的效率.
Transferability between Isolated Joint Torques and a Maximum Polyarticular Task: A Preliminary Study
Costes Antony
2016-04-01
Full Text Available The aims of this study were to determine if isolated maximum joint torques and joint torques during a maximum polyarticular task (i.e. cycling at maximum power are correlated despite joint angle and velocity discrepancies, and to assess if an isolated joint-specific torque production capability at slow angular velocity is related to cycling power. Nine cyclists completed two different evaluations of their lower limb maximum joint torques. Maximum Isolated Torques were assessed on isolated joint movements using an isokinetic ergometer and Maximum Pedalling Torques were calculated at the ankle, knee and hip for flexion and extension by inverse dynamics during cycling at maximum power. A correlation analysis was made between Maximum Isolated Torques and respective Maximum Pedalling Torques [3 joints x (flexion + extension], showing no significant relationship. Only one significant relationship was found between cycling maximum power and knee extension Maximum Isolated Torque (r=0.68, p<0.05. Lack of correlations between isolated joint torques measured at slow angular velocity and the same joint torques involved in a polyarticular task shows that transfers between both are not direct due to differences in joint angular velocities and in mono-articular versus poly articular joint torque production capabilities. However, this study confirms that maximum power in cycling is correlated with slow angular velocity mono-articular maximum knee extension torque.
Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes
Saidaoui, Hamed Ben Mohamed
2014-05-28
Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green\\'s function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.
无刷直流电机调速系统转矩脉动抑制方法研究%Research on torque ripple suppression method for BLDCM speed control system
李有凯; 蒋玲
2016-01-01
通过对无刷直流电机开通期间的相电流和关断期间的相电流分析，经过实际计算得到电磁转矩的表达式，得到相应的电磁转矩脉动曲线。基于电流预测方法通过将预测模型分为模型建立、反馈调整和性能优化3步，通过控制换相电流保持在稳定的状态，从而实现对转矩脉动的抑制。通过仿真和实际实验表明，该无刷直流电机调速系统在实际运行中具有转矩脉动小、响应速度快等优点。%The phase current of BLDCM during the opening period and shutdown period is analyzed. The electromagnetic torque expression is obtained by actual calculation,and then the corresponding electromagnetic torque ripple curve is obtained. The prediction model is divided into model establishment,feedback tuning and performance optimization with current prediction method. The phase commutation current is controlled in a stable state to suppress the torque ripple. The simulation and practical experiment results show that the BLDCM speed control system has the advantages of small torque ripple,fast response speed,etc.
Insertion torque, resonance frequency, and removal torque analysis of microimplants.
Tseng, Yu-Chuan; Ting, Chun-Chan; Du, Je-Kang; Chen, Chun-Ming; Wu, Ju-Hui; Chen, Hong-Sen
2016-09-01
This study aimed to compare the insertion torque (IT), resonance frequency (RF), and removal torque (RT) among three microimplant brands. Thirty microimplants of the three brands were used as follows: Type A (titanium alloy, 1.5-mm × 8-mm), Type B (stainless steel, 1.5-mm × 8-mm), and Type C (titanium alloy, 1.5-mm × 9-mm). A synthetic bone with a 2-mm cortical bone and bone marrow was used. Each microimplant was inserted into the synthetic bone, without predrilling, to a 7 mm depth. The IT, RF, and RT were measured in both vertical and horizontal directions. One-way analysis of variance and Spearman's rank correlation coefficient tests were used for intergroup and intragroup comparisons, respectively. In the vertical test, the ITs of Type C (7.8 Ncm) and Type B (7.5 Ncm) were significantly higher than that of Type A (4.4 Ncm). The RFs of Type C (11.5 kHz) and Type A (10.2 kHz) were significantly higher than that of Type B (7.5 kHz). Type C (7.4 Ncm) and Type B (7.3 Ncm) had significantly higher RTs than did Type A (4.1 Ncm). In the horizontal test, both the ITs and RTs were significantly higher for Type C, compared with Type A. No significant differences were found among the groups, and the study hypothesis was accepted. Type A had the lowest inner/outer diameter ratio and widest apical facing angle, engendering the lowest IT and highest RF values. However, no significant correlations in the IT, RF, and RT were observed among the three groups.
捌色兴佳; 王晓东; 单光坤; 刘姝
2012-01-01
Torque vibration is an important reason of wind turbine drive train fatigue damage.The nonlinear and uncertainty characteristics in drive train are analyzed firstly in this paper.A torque vibration control method is designed based on active disturbances rejection control technique.The external disturbances and uncertainties of drive train,which include gear engaging dynamic stiffness,gear engaging error and flexible coupling nonlinear stiffness and damping etc.,are integrated as compositive disturbances.The compositive disturbances are estimated with extended state observer and compensated during torque vibration control.The torque vibration controller is evaluated based on a 3MW doubly fed variable speed wind turbine.The simulation result shows that the gearbox torque vibration is mitigated obviously on the premise of not affecting generator output power.%扭振是造成风电机组传动系统零部件疲劳损伤的主要原因之一。为了通过控制减小风电机组传动系统疲劳载荷,本文在分析风电机组传动系统中非线性不确定因素作用的基础上,设计了一种扭振抑制自抗扰控制器。该控制器将传动系统中的非线性不确定因素作用和外界扰动归结为系统总扰动,通过扩张状态观测器进行实时估计,并在发电机转矩控制中给予补偿,增强了控制器的适应性和鲁棒性。以3MW双馈风电机组为控制对象的试验结果表明,该控制器可以在不影响机组发电量的前提下抑制传动系统扭振,明显减小齿轮箱的转矩波动,从而减轻扭转载荷对主要零部件的疲劳损伤。
Xu, Xiaohao; Cheng, Chang; Zhang, Yao; Lei, Hongxiang; Li, Baojun
2016-01-21
Linearly polarized light can exert an orienting torque on plasmonic nanorods. The torque direction has generally been considered to change when the light wavelength passes through a plasmon longitudinal resonance. Here, we use the Maxwell stress tensor to evaluate this torque in general terms. According to distinct light-matter interaction processes, the total torque is decomposed into scattering and extinction torques. The scattering torque tends to orient plasmonic nanorods parallel to the light polarization, independent of the choice of light wavelength. The direction of the extinction torque is not only closely tied to the excitation of plasmon resonance but also depends on the specific plasmon mode around which the light wavelength is tuned. Our findings show that the conventional wisdom that simply associates the total torque with the plasmon longitudinal resonances needs to be replaced with an understanding based on the different torque components and the details of spectral distribution.
Single-interface Casimir torque
Morgado, Tiago A.; Silveirinha, Mário G.
2016-10-01
A different type of Casimir-type interaction is theoretically predicted: a single-interface torque at a junction of an anisotropic material and a vacuum or another material system. The torque acts to reorient the polarizable microscopic units of the involved materials near the interface, and thus to change the internal structure of the materials. The single-interface torque depends on the zero-point energy of the interface localized and extended modes. Our theory demonstrates that the single-interface torque is essential to understand the Casimir physics of material systems with anisotropic elements and may influence the orientation of the director of nematic liquid crystals.
Force measurement and design of a torquing high-pull headgear.
Tabash, J W; Sandrik, J L; Bowman, D; Lang, R L; Klapper, L
1984-07-01
The dynamic extraoral force analyzer (DEFA) was found to be capable of measuring linear deflection as a function of force created by a headgear. Ten standard nontorqued face-bows with a cervical and a high-pull direction were tested to determine the reliability of the DEFA. Statistical analysis showed the DEFA to be reliable and accurate in differentiating various directions and deflections of maxillary molars. Doubled-over distal ends of the inner bow with 0 degree of torque and a parietal direction of pull were used as controls. The same face-bows with 9 degrees of buccal root torque were tested on the DEFA. These face-bows were tested to determine whether transverse translation without buccal crown tipping of the maxillary first molar will occur. Statistical analysis showed that transverse translation occurred at a force of 200 to 347 gm.
Interaction torque contributes to planar reaching at slow speed
Hoshi Fumihiko
2008-10-01
Full Text Available Abstract Background How the central nervous system (CNS organizes the joint dynamics for multi-joint movement is a complex problem, because of the passive interaction among segmental movements. Previous studies have demonstrated that the CNS predictively compensates for interaction torque (INT which is arising from the movement of the adjacent joints. However, most of these studies have mainly examined quick movements, presumably because the current belief is that the effects of INT are not significant at slow speeds. The functional contribution of INT for multijoint movements performed in various speeds is still unclear. The purpose of this study was to examine the contribution of INT to a planer reaching in a wide range of motion speeds for healthy subjects. Methods Subjects performed reaching movements toward five targets under three different speed conditions. Joint position data were recorded using a 3-D motion analysis device (50 Hz. Torque components, muscle torque (MUS, interaction torque (INT, gravity torque (G, and net torque (NET were calculated by solving the dynamic equations for the shoulder and elbow. NET at a joint which produces the joint kinematics will be an algebraic sum of torque components; NET = MUS - G - INT. Dynamic muscle torque (DMUS = MUS-G was also calculated. Contributions of INT impulse and DMUS impulse to NET impulse were examined. Results The relative contribution of INT to NET was not dependent on speed for both joints at every target. INT was additive (same direction to DMUS at the shoulder joint, while in the elbow DMUS counteracted (opposed to INT. The trajectory of reach was linear and two-joint movements were coordinated with a specific combination at each target, regardless of motion speed. However, DMUS at the elbow was opposed to the direction of elbow movement, and its magnitude varied from trial to trial in order to compensate for the variability of INT. Conclusion Interaction torque was important at
Special-Purpose High-Torque Permanent-Magnet Motors
Doane, George B., III
1995-01-01
Permanent-magnet brushless motors that must provide high commanded torques and satisfy unusual heat-removal requirement are developed. Intended for use as thrust-vector-control actuators in large rocket engines. Techniques and concepts used to design improved motors for special terrestrial applications. Conceptual motor design calls for use of rotor containing latest high-energy-product rare-earth permanent magnets so that motor produces required torque while drawing smallest possible currents from power supply. Torque generated by electromagnetic interaction between stator and permanent magnets in rotor when associated electronic circuits applied appropriately temporally and spatially phased currents to stator windings. Phase relationships needed to produce commanded torque computed in response to torque command and to electronically sensed angular position of rotor relative to stator.
Controller for a High-Power, Brushless dc Motor
Fleming, David J.; Makdad, Terence A.
1987-01-01
Driving and braking torques controllable. Control circuit operates 7-kW, 45-lb-ft (61-N-m), three-phase, brushless dc motor in both motor and generator modes. In motor modes, energy from power source is pulse-width modulated to motor through modified "H-bridge" circuit, in generator mode, energy from motor is pulse-width modulated into bank of load resistors to provide variable braking torques. Circuit provides high-resolution torque control in both directions over wide range of speeds and torques. Tested successfully at bus voltages up to 200 Vdc and currents up to 45 A.
Wang, X.-G.; Chotorlishvili, L.; Guo, G.-H.; Sukhov, A.; Dugaev, V.; Barnaś, J.; Berakdar, J.
2016-09-01
Thermally activated domain-wall (DW) motion in magnetic insulators has been considered theoretically, with a particular focus on the role of Dzyaloshinskii-Moriya interaction (DMI) and thermomagnonic torques. The thermally assisted DW motion is a consequence of the magnonic spin current due to the applied thermal bias. In addition to the exchange magnonic spin current and the exchange adiabatic and the entropic spin transfer torques, we also consider the DMI-induced magnonic spin current, thermomagnonic DMI fieldlike torque, and the DMI entropic torque. Analytical estimations are supported by numerical calculations. We found that the DMI has a substantial influence on the size and the geometry of DWs, and that the DWs become oriented parallel to the long axis of the nanostrip. Increasing the temperature smoothes the DWs. Moreover, the thermally induced magnonic current generates a torque on the DWs, which is responsible for their motion. From our analysis it follows that for a large enough DMI the influence of DMI-induced fieldlike torque is much stronger than that of the DMI and the exchange entropic torques. By manipulating the strength of the DMI constant, one can control the speed of the DW motion, and the direction of the DW motion can be switched, as well. We also found that DMI not only contributes to the total magnonic current, but also it modifies the exchange magnonic spin current, and this modification depends on the orientation of the steady-state magnetization. The observed phenomenon can be utilized in spin caloritronics devices, for example in the DMI based thermal diodes. By switching the magnetization direction, one can rectify the total magnonic spin current.
Spin-Stabilized Spacecrafts: Analytical Attitude Propagation Using Magnetic Torques
Roberta Veloso Garcia
2009-01-01
Full Text Available An analytical approach for spin-stabilized satellites attitude propagation is presented, considering the influence of the residual magnetic torque and eddy currents torque. It is assumed two approaches to examine the influence of external torques acting during the motion of the satellite, with the Earth's magnetic field described by the quadripole model. In the first approach is included only the residual magnetic torque in the motion equations, with the satellites in circular or elliptical orbit. In the second approach only the eddy currents torque is analyzed, with the satellite in circular orbit. The inclusion of these torques on the dynamic equations of spin stabilized satellites yields the conditions to derive an analytical solution. The solutions show that residual torque does not affect the spin velocity magnitude, contributing only for the precession and the drift of the spacecraft's spin axis and the eddy currents torque causes an exponential decay of the angular velocity magnitude. Numerical simulations performed with data of the Brazilian Satellites (SCD1 and SCD2 show the period that analytical solution can be used to the attitude propagation, within the dispersion range of the attitude determination system performance of Satellite Control Center of Brazil National Research Institute.
Van der Waals torque induced by external magnetic fields
Esquivel-Sirvent, R; Palomono-Ovando, M
2010-01-01
We present a method for inducing and controlling van der Waals torques between two parallel slabs using a constant magnetic field. The torque is calculated using the Barash theory of dispersive torques. In III-IV semiconductors such as $InSb$, the effect of an external magnetic field is to induce an optical anisotropy, in an otherwise isotropic material, that will in turn induce a torque. The calculations of the torque are done in the Voigt configuration, with the magnetic field parallel to the surface of the slabs. As a case study we consider a slab made of calcite and a second slab made of $InSb$. In the absence of magnetic field there is no torque. As the magnetic field increases, the optical anisotropy of $InSb$ increases and the torque becomes different from zero, increasing with the magnetic field. The resulting torque is of the same order of magnitude as that calculated using permanent anisotropic materials when the magnetic fields is close to 1 T.
Van der Waals torque induced by external magnetic fields
Esquivel-Sirvent, R.; Cocoletzi, G. H.; Palomino-Ovando, M.
2010-01-01
We present a method for inducing and controlling van der Waals torques between two parallel slabs using a constant magnetic field. The torque is calculated using the Barash theory of dispersive torques. In III–IV semiconductors such as InSb, the effect of an external magnetic field is to induce an optical anisotropy, in an otherwise isotropic material, that will in turn induce a torque. The calculations of the torque are done in the Voigt configuration, with the magnetic field parallel to the surface of the slabs. As a case study we consider a slab made of calcite and a second slab made of InSb. In the absence of magnetic field there is no torque. As the magnetic field increases, the optical anisotropy of InSb increases and the torque becomes different from zero, increasing with the magnetic field. The resulting torque is of the same order of magnitude as that calculated using permanent anisotropicmaterials when the magnetic fields is close to 1 T.
周羽; 李槐树; 苏广东
2013-01-01
为了研究多相梯形波永磁同步电动机(以下简称TPMSM)的换流转矩脉动,基于Y-Y移30°电角度的六相TPMSM建立电流型调速系统的数学模型,给出了换流重叠角的计算公式,并利用仿真分析了换相超前角和换流重叠角之间的关系以及换相超前角和转矩脉动之间的关系.结果表明,减小换相超前角有利于减小转矩脉动,但是会增加换流重叠角,甚至导致换流失败.%In order to study the commutation torque ripple of multiphase trapezia-wave permanent magnet synchronous motor (TPMSM) ,the mathematical model of current-type speed control system was established based on the six-phase TPMSM with Y-Y winding shifting 30° electric-degree. The calculating formula of commutating angular overlap was given. And the relationship of commutating angle and commutating angular overlap and relationship of commutating angular overlap and torque ripple were analyzed. The results show that reducing commutating angle is beneficial to reducing torque ripple, but it will increase commutating angular overlap,even bring on the failure of commutation.
Shimizu, Y.; Takada, M.; Maeda, T. [Mie University, Mie (Japan). Faculty of Engineering; Kamikawa, H.; Marumo, T. [Mie University, Mie (Japan)
1998-03-01
An inverter-assisted variable speed power generation system is subjected to a field test and the optimum slip for optimum operation against changing wind velocities is determined. The system is a horizontal-axis wind turbine of the up-wind type provided with three variable-pitch blades. The rotor is 8.2m in diameter, the rotation axis is positioned 12.7m above the ground, and the output is rated at 8kW. The rotation of the rotor is multiplied nine times by a step-up gear using a timing belt, and drives the 8-pole/3-phase squirrel-cage 8kW induction generator whose rotation is rated at 900rpm. The generated AC power is converted into DC by transistors before being charged into storage batteries. In the experiment, power is generated at variable speeds using the inverter and four types of second-power torque control are tested, different from each other in the magnitude of slips. After an overall evaluation of the amount of generated power and system efficiency, it is found that a slip of -2.0% is the optimum for the control of power generation in this type of wind turbine. 1 ref., 8 figs.
A Study on the Influence of Commutation Time on Torque Pulsating in BLDCM
Kim, Choel Ju; Kang, Byoung Hee; Mok, Hyoung Su; Choe, Gyu-Ha [Konkuk University, Seoul(Korea)
2001-01-01
A BLDC motor has a serious drawback that torque pulsation is generated in every commutation period though it has many advantages compared to the conventional DC Motor. In this paper, the influence of commutation time on torque pulsation is studied. Generally in calculating the torque of BLDC motor, it is assumed that the decaying phase back EMF is constant, but the torque model considering decaying phase back EMF is introduced here. Through it, the torque in commutation period has torque pulsation component caused by commutation itself and it cannot be removed perfectly even if there is no current and pulsation. To reduce the torque pulsation, a new method is proposed, which controls a point of commutation and the optimal point of commutation is found. Simulation shows proposed method reduces the torque pulsation considerately. (author). 5 refs., 8 figs., 2 tabs.
Comparison of different passive knee extension torque-angle assessments.
Freitas, Sandro R; Vaz, João R; Bruno, Paula M; Valamatos, Maria J; Mil-Homens, Pedro
2013-11-01
Previous studies have used isokinetic dynamometry to assess joint torques and angles during passive extension of the knee, often without reporting upon methodological errors and reliability outcomes. In addition, the reliability of the techniques used to measure passive knee extension torque-angle and the extent to which reliability may be affected by the position of the subjects is also unclear. Therefore, we conducted an analysis of the intra- and inter-session reliability of two methods of assessing passive knee extension: (A) a 2D kinematic analysis coupled to a custom-made device that enabled the direct measurement of resistance to stretch and (B) an isokinetic dynamometer used in two testing positions (with the non-tested thigh either flexed at 45° or in the neutral position). The intra-class correlation coefficients (ICCs) of torque, the slope of the torque-angle curve, and the parameters of the mathematical model that were fit to the torque-angle data for the above conditions were measured in sixteen healthy male subjects (age: 21.4 ± 2.1 yr; BMI: 22.6 ± 3.3 kg m(-2); tibial length: 37.4 ± 3.4 cm). The results found were: (1) methods A and B led to distinctly different torque-angle responses; (2) passive torque-angle relationship and stretch tolerance were influenced by the position of the non-tested thigh; and (3) ICCs obtained for torque were higher than for the slope and for the mathematical parameters that were fit to the torque-angle curve. In conclusion, the measurement method that is used and the positioning of subjects can influence the passive knee extension torque-angle outcome.
ESTIMATION OF GRASPING TORQUE USING ROBUST REACTION TORQUE OBSERVER FOR ROBOTIC FORCEPS
塚本, 祐介; Tsukamoto, Yusuke
2015-01-01
Abstract— In this paper, the estimation of the grasping torque of robotic forceps without the use of a force/torque sensor is discussed. To estimate the grasping torque when the robotic forceps driven by a rotary motor with a reduction gear grasps an object, a novel robust reaction torque observer is proposed. In the case where a conventional reaction force/torque observer is applied, the estimated torque includes not only the grasping torque, namely the reaction torque, but also t...
Evelt, M.; Demidov, V. E., E-mail: demidov@uni-muenster.de [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, 48149 Muenster (Germany); Bessonov, V. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Yekaterinburg 620041 (Russian Federation); Demokritov, S. O. [Institute for Applied Physics and Center for Nanotechnology, University of Muenster, 48149 Muenster (Germany); M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, Yekaterinburg 620041 (Russian Federation); Prieto, J. L. [Instituto de Sistemas Optoelectrónicos y Microtecnologa (UPM), Ciudad Universitaria, Madrid 28040 (Spain); Muñoz, M. [IMM-Instituto de Microelectrónica de Madrid (CNM-CSIC), PTM, E-28760 Tres Cantos, Madrid (Spain); Ben Youssef, J. [Laboratoire de Magnétisme de Bretagne CNRS, Université de Bretagne Occidentale, 29285 Brest (France); Naletov, V. V. [Service de Physique de l' État Condensé, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette (France); Institute of Physics, Kazan Federal University, Kazan 420008 (Russian Federation); Loubens, G. de [Service de Physique de l' État Condensé, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191 Gif-sur-Yvette (France); Klein, O. [INAC-SPINTEC, CEA/CNRS and Univ. Grenoble Alpes, 38000 Grenoble (France); Collet, M.; Garcia-Hernandez, K.; Bortolotti, P.; Cros, V.; Anane, A. [Unité Mixte de Physique CNRS, Thales, Univ. Paris Sud, Université Paris-Saclay, 91767 Palaiseau (France)
2016-04-25
We study experimentally with submicrometer spatial resolution the propagation of spin waves in microscopic waveguides based on the nanometer-thick yttrium iron garnet and Pt layers. We demonstrate that by using the spin-orbit torque, the propagation length of the spin waves in such systems can be increased by nearly a factor of 10, which corresponds to the increase in the spin-wave intensity at the output of a 10 μm long transmission line by three orders of magnitude. We also show that, in the regime, where the magnetic damping is completely compensated by the spin-orbit torque, the spin-wave amplification is suppressed by the nonlinear scattering of the coherent spin waves from current-induced excitations.
An ironless armature brushless torque motor
Studer, P. A.
1973-01-01
A high torque motor with improved servo mechanism is reported. Armature windings are cast into an epoxy cylinder and armature conductors are integrally cast with an aluminum mounting ring which provides thermal conductance directly into the structure. This configuration eliminates magnetic hysteresis because there is no relative motion between the rotating magnetic field and any stationary iron. The absence of destabilization forces provides a fast electrical response compared with a typical torquer of conventional construction.
Experimental Robot Position Sensor Fault Tolerance Using Accelerometers and Joint Torque Sensors
Aldridge, Hal A.; Juang, Jer-Nan
1997-01-01
Robot systems in critical applications, such as those in space and nuclear environments, must be able to operate during component failure to complete important tasks. One failure mode that has received little attention is the failure of joint position sensors. Current fault tolerant designs require the addition of directly redundant position sensors which can affect joint design. The proposed method uses joint torque sensors found in most existing advanced robot designs along with easily locatable, lightweight accelerometers to provide a joint position sensor fault recovery mode. This mode uses the torque sensors along with a virtual passive control law for stability and accelerometers for joint position information. Two methods for conversion from Cartesian acceleration to joint position based on robot kinematics, not integration, are presented. The fault tolerant control method was tested on several joints of a laboratory robot. The controllers performed well with noisy, biased data and a model with uncertain parameters.
大型风力发电机转矩LQR控制及载荷优化%Load reduction for large-scale wind turbine based on LQR torque control
金鑫; 钟翔; 谢双义; 罗敏; 何玉林; 杜静
2013-01-01
Traditional way of control for wind turbine employs a constant torque for generator above rated wind speed while using pitch control to regulate rotor speed. It results in a quite low damp ratio of the drive train torsional mode which would invoke large fluctuation in drive train torque, and even oscillate the structure. In concern of this problem, the paper designs a linear quadratic regulator (LQR) to dynamically control the generator torque. By moving the closed-loop poles corresponding to the first order drive train torsion mode further to the left in the complex plane, the generator torque controller adds active damping to this mode. After extracting linear state space model of the drive train, Matlab7.1/Simulink is used to design the controller and FAST is engaged in the co-simulation. The results show that the proposed control mean successfully adds damping to the drive train and reduces loads of the key components of wind turbine.% 传统的风力发电机的控制方法在高于额定风速时，采用变桨距限制风轮转速，同时采用恒定的转矩控制电机转矩.恒定的电机转矩导致风力发电机传动链扭转阻尼比很小，使传动链扭矩大幅度的波动，甚至引起风力机结构的共振.针对该问题，建立了传动链基于状态空间的线性化模型，采用 LQR(Linear Quadratic Regulator)方法设计风力发电机的转矩控制器，将传动链一阶扭转模态对应的闭环极点向虚平面的左侧移动，实现对传动链进行动态加阻.采用 FAST的计算模块获得了风力发电机传动链的线性化状态空间模型，采用Matlab7.1/Simulink进行控制器设计并与FAST进行联合仿真.结果表明提出的控制方法有效地提高了传动链的阻尼，降低了风力发电机组关键零部件的载荷.
Kusuma Gottapu
2014-04-01
Full Text Available This paper presents an improved version of direct torque control (DTC based on Artificial Neural Network technique used for flux position estimation and sector selection. This controller mainly reduces the torque and flux ripples. Direct torque control of induction motor drive has quick torque response without complex orientation transformation and inner loop current control. The major problem associated with DTC drive is the high torque ripples. The important point in ANN based DTC is the right selection of voltage vector. This project presents simple structured neural network for flux position estimation and sector selection for induction motor. The Levenberg-Marquardt back propagation technique has been used to train the neural networks. The simple structure network facilitates a short training and processing times. The neural network based controller is found to be a very useful technique to obtain high performance speed control.
van den Beld, Wesley Theodorus Eduardus; van den Berg, Albert; Eijkel, Jan C.T.
2016-01-01
In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated
Beld, van den Wesley T.E.; Berg, van den Albert; Eijkel, Jan C.T.
2016-01-01
In this paper we present a method for the spatial control of direct graphene synthesis onto silicon dioxide by controlled dewetting. The dewetting process is controlled through a combination of using a grooved substrate and conducting copper deposition at an angle. The substrate is then treated usin
The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures
Grollier, Julie
2013-03-01
Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.
Position Servo Control for a Direct-Drive Actuator Based on Genetic Algorithm
Baifen Liu
2013-05-01
Full Text Available A novel position control strategy for a Brushless DC motor (BLDC drive is proposed in this paper. Brushless DC motor, which is widely used in the field of Direct Drive servo Actuator (DDA with superior performance, possesses fast transient response and high accuracy. Nevertheless, there are such uncertainties as unpredictable flow torques and estimated errors of the BLDC model in this system, which may influence the accuracy and the rapid response of the control. So in this paper, genetic algorithm is applied to the position loop. Simultaneously, in order to improve the rapidness of the whole system, position and velocity double closed-loop system is compared with position and current double closed-loop system. Experimental results validate the scheme proposed can attenuate the influences by the uncertainties of the model sharply. The genetic algorithm used in the position loop can ensure the system's stability and the accuracy of the position response. While tracking the same step response the step rise time of the double closed loop structure of the position and current reduced more than 25% compared with that of the double closed loop structure of the position and velocity.
An Intuitive Definition of Demand Flexibility in Direct Load Control
Tahersima, Fatemeh; Madsen, Per Printz; Andersen, Palle
2013-01-01
Two control approaches: direct and indirect control of demand side energy management in a smart grid are studied. Indirect control of energy demands is based on economic incentives. In this approach, consumers will shift their energy consumption with the benefit of a cut down in the electricity...
Cogging torque mitigation of modular permanent magnet machines
Li, G. J.; Ren, B.; Zhu, Z-Q.; Li, Y X; Ma, J.
2015-01-01
This paper proposes a novel cogging torque mitigation method for modular permanent magnet (PM) machines with flux gaps in alternate stator teeth. The slot openings of the modular PM machines are divided into two groups in a special way. By shifting the slot openings of two groups in opposite directions with the same angle, the machine cogging torque can be significantly reduced. Analytical formula of the desired shift angle is derived, and can be applicable to other modular machines with diff...
Controllability of Weighted and Directed Networks with Nonidentical Node Dynamics
Linying Xiang
2013-01-01
Full Text Available The concept of controllability from control theory is applied to weighted and directed networks with heterogenous linear or linearized node dynamics subject to exogenous inputs, where the nodes are grouped into leaders and followers. Under this framework, the controllability of the controlled network can be decomposed into two independent problems: the controllability of the isolated leader subsystem and the controllability of the extended follower subsystem. Some necessary and/or sufficient conditions for the controllability of the leader-follower network are derived based on matrix theory and graph theory. In particular, it is shown that a single-leader network is controllable if it is a directed path or cycle, but it is uncontrollable for a complete digraph or a star digraph in general. Furthermore, some approaches to improving the controllability of a heterogenous network are presented. Some simulation examples are given for illustration and verification.
Current-induced torques and interfacial spin-orbit coupling
Haney, Paul M.
2013-12-19
In bilayer systems consisting of an ultrathin ferromagnetic layer adjacent to a metal with strong spin-orbit coupling, an applied in-plane current induces torques on the magnetization. The torques that arise from spin-orbit coupling are of particular interest. Here we use first-principles methods to calculate the current-induced torque in a Pt-Co bilayer to help determine the underlying mechanism. We focus exclusively on the analog to the Rashba torque, and do not consider the spin Hall effect. The details of the torque depend strongly on the layer thicknesses and the interface structure, providing an explanation for the wide variation in results found by different groups. The torque depends on the magnetization direction in a way similar to that found for a simple Rashba model. Artificially turning off the exchange spin splitting and separately the spin-orbit coupling potential in the Pt shows that the primary source of the “fieldlike” torque is a proximate spin-orbit effect on the Co layer induced by the strong spin-orbit coupling in the Pt.
Hybrid synchronous motor electromagnetic torque research
Suvorkova Elena E.
2014-01-01
Full Text Available Electromagnetic field distribution models in reluctance and permanent magnet parts were made by means of Elcut. Dependences of electromagnetic torque on torque angle were obtained.
田以涛; 王英
2013-01-01
在分析永磁同步电动机数学模型基础上,通过极值原理推导出基于最大转矩电流比控制方法下电磁转矩与d、q轴电流之间的关系式,给出了一种关系式的工程近似求解方法,分析了3次拟合多项式与5次拟合多项式下的拟合特点.分析结果表明5次拟合情况下的电机空载运行电流明显小于3次拟合情况下的电机空载运行电流,有利于降低电机空载运行时的损耗.仿真对比了两种拟合多项式控制下的电机运行状态,仿真结果与理论分析相符.%Based on the mathematical model of permanent magnet synchronous motor (PMSM),the relational expression between electromagnetic torque and d-axes,q-axes current,was controlled based on maximum torque per ampere (MTPA),which was deduced according to extremal principle.An engineering approximate algorithm for the maximum torque per ampere control was given.And the fitting characteristic of three times fitting polynomial and five times fitting polynomial was analyzed.The current of the motor no-load running under five times polynomial was obviously lower than that under three times polynomial,which helped to reduce the motor no-load running loss.The motor operation under the control of two fitting polynomial was compared by the simulation.The simulation result was consistent with the theoretical analysis.
Multiple Property Cross Direction Control of Paper Machines
Markku Ohenoja
2011-07-01
Full Text Available Cross direction (CD control in sheet-forming process forms a challenging problem with high dimensions. Accounting the interactions between different properties and actuators, the dimensionality increases further and also computational issues arise. We present a multiple property controller feasible to be used especially with imaging measurements that provide high sampling frequency and therefore enable short control interval. The simulation results state the benefits of multiple property CD control over single property control and single property control using full feedforward compensation. The controller presented may also be tuned in automated manner and the results demonstrate the effect of tuning on input saturation.
Adiabatic and nonadiabatic spin torques induced by a spin-triplet supercurrent
Takashima, Rina; Fujimoto, Satoshi; Yokoyama, Takehito
2017-09-01
We study spin-transfer torques induced by a spin-triplet supercurrent in a magnet with the superconducting proximity effect. By a perturbative approach, we show that spin-triplet correlations realize new types of torques, which are analogous to the adiabatic and nonadiabatic (β ) torques, without extrinsic spin-flip scattering. Remarkable advantages compared to conventional spin-transfer torques are highlighted in domain-wall manipulation. Oscillatory motions of a domain wall do not occur for a small Gilbert damping, and the threshold current density to drive its motion becomes zero in the absence of extrinsic pinning potentials due to the nonadiabatic torque controlled by the triplet correlations.
秦燕军; 顾月光; 刘可; 于剑南; 沈云娟; 赵宏; 赵春洋
2014-01-01
目的：探讨控根辅弓对直丝弓矫治器患者的上颌切牙转矩效果。方法：选择22例安氏Ⅱ1拔牙矫治的患者，采用直丝弓矫治器矫治，在精细调整阶段配合控根辅弓对过度直立或内倾的上颌切牙进行正转矩。按主弓丝不同分为2组，14例主弓丝为0．46 mm ×0．64 mm 的不锈钢方丝，8例主弓丝为0．46 mm 的不锈钢圆丝。对22例上颌切牙转矩前后的 X 线头影测量结果采用 t 检验进行统计分析。结果：22例上颌切牙转矩后的 X 线头影测量结果显示，1-SN、UIa-NA 值增加（P ＜0．01），控根辅弓对上切牙的正转矩效果明显；转矩的时间，主弓丝为圆丝上颌切牙转矩快于主弓丝为方丝，P ＜0．05。结论：在直丝弓矫治的精细调整阶段，配合前牙控根辅弓，是对内收后过度直立或舌倾的上颌切牙实现转矩的简单、有效的方法。%Objective:To explore the torque effect of controlling root auxiliary arch on the straight wire appliance on maxillary anterior teeth.Methods:22 patients with class Ⅱ1 extraction treatment,treated with straightwire appliance,at the detailing treatment stage were treated with controlling root auxiliary arch over the erect or introverted maxillary incisors for positive torque.The main arch wire of 0.46 mm ×0.64 mm stainless steel edge wire was used in 14 cases,the main arch wire of 0.46 mm stainless steel round wire was used in 8 cases.Cephalometric results before and after maxillary incisor torque were analyzed by t test.Results:After maxillary incisor torque in the 22 cases 1-SN and UIa-NA value increased(P <0.01),positive torque was achieved by controlling root auxiliary arch on the upper incisors;the round wire maxillary incisor torque worked faster than the edge wire(P <0.05).Conclusion:At the detailing stage of treatment straight wire appliance on front teeth,controlling root auxiliary arch is simple and effective in the treatment of exces
Tobacco Products Directive - new opportunities for EU tobacco control
Anna-Eva Ampelas
2016-03-01
Full Text Available The Tobacco Products Directive 2014/40/EU was adopted in 2014 and needs to be transposed by Member States by 20 May 2016. It sets out ambitious tobacco control measures in the areas of ingredients, packaging & labelling, electronic cigarettes and tracking & tracing. The new Directive focuses on preventing young people from taking up smoking.
Strategic directions of government control of national information space
Ірина Романівна Боднар
2015-03-01
Full Text Available The main directions of state information politics are considered. The legal framework and functioning of national information sphere is analyzed. The basic directions of government control of Ukraine's information space are considered. The approaches to the efficiency of the national information system are proposed
Analyzing the installation angle error of a SAW torque sensor
Fan, Yanping; Ji, Xiaojun; Cai, Ping
2014-09-01
When a torque is applied to a shaft, normal strain oriented at ±45° direction to the shaft axis is at its maximum, which requires two one-port SAW resonators to be bonded to the shaft at ±45° to the shaft axis. In order to make the SAW torque sensitivity high enough, the installation angle error of two SAW resonators must be confined within ±5° according to our design requirement. However, there are few studies devoted to the installation angle analysis of a SAW torque sensor presently and the angle error was usually obtained by a manual method. Hence, we propose an approximation method to analyze the angle error. First, according to the sensitive mechanism of the SAW device to torque, the SAW torque sensitivity is deduced based on the linear piezoelectric constitutive equation and the perturbation theory. Then, when a torque is applied to the tested shaft, the stress condition of two SAW resonators mounted with an angle deviating from ±45° to the shaft axis, is analyzed. The angle error is obtained by means of the torque sensitivities of two orthogonal SAW resonators. Finally, the torque measurement system is constructed and the loading and unloading experiments are performed twice. The torque sensitivities of two SAW resonators are obtained by applying average and least square method to the experimental results. Based on the derived angle error estimation function, the angle error is estimated about 3.447°, which is close to the actual angle error 2.915°. The difference between the estimated angle and the actual angle is discussed. The validity of the proposed angle error analysis method is testified to by the experimental results.
Analysis of torque-current characteristic of brushless DC motor driven by three-phase H-bridge
无
2000-01-01
Presents the simulation and analysis of the steady state characteristic of a brushless DC motor studies the torque-current characteristic of the motor as well and discusses the design of a current-measure circuit for torque controlling.
火炮直驱伺服系统的模型校正控制%Model Correction Control for Gun Direct Drive Servo System
刘妙; 张光辉; 刘攀玲; 马佳佳; 王佳雯
2016-01-01
射击时，火炮采用的直驱技术会对射击准确性产生较大的影响。为了削减射击力矩的影响，采用了一种火炮直驱伺服系统的模型校正控制方法。以某多管并联火炮为例计算了其单管射击力矩，建立了考虑射击力矩因素的校正控制模型，并利用 Matlab／Simulink对其进行数值仿真。仿真结果显示模型校正控制可以削弱射击力矩的影响，并且在短时间内达到稳定。该仿真结果为火炮直驱伺服系统的设计起到指导作用。%The shooting torque inevitably acted on the motor when the direct drive technology was used in the manufacture of a gun,which brought a negative impact on the accuracy of the design. In order to minimize the influence of the shooting torque,a model correction control method of the gun direct drive servo system was adopted. On the basis of a certain multi-tube parallel gun,its single tube shoo-ting torque was calculated;the correction control model with shooting torque factor taken into account was established and numerical simulation using Matlab/Simulink was carried out. The simulation re-sults show that the improved method can be used to weaken the influence of the shooting torque and to help the gun reach acceptable stability in a short period of time. The method and its simulation results will provide reference for the design of the Gun Direct Drive Servo System.
Torque analysis for double-stator permanent-magnet motor
柴凤; 程树康; 崔淑梅
2002-01-01
In addition to the characteristics of a conventional motor, a novel direct-drive double-stator perma-nent-magnet brushless motor proposed can operate in the state of either a generator or a motor as appropriate.Through numerical calculation and analysis, the output torque of double-stator permanent-magnet brushless motor of the same volume as the traditional machine is discussed, and the reduction of torque ripple by using the structure features of this motor is investigated. The results indicate that lower torque ripple under the condition of ideal effective torque can be obtained by the rational design of motor. The prototype motors tested show that this kind of motor structure has a higher power density.
Mechanics of torque generation in the bacterial flagellar motor
Mandadapu, Kranthi K; Berry, Richard M; Oster, George
2015-01-01
The bacterial flagellar motor (BFM) is responsible for driving bacterial locomotion and chemotaxis, fundamental processes in pathogenesis and biofilm formation. In the BFM, torque is generated at the interface between transmembrane proteins (stators) and a rotor. It is well-established that the passage of ions down a transmembrane gradient through the stator complex provides the energy needed for torque generation. However, the physics involved in this energy conversion remain poorly understood. Here we propose a mechanically specific model for torque generation in the BFM. In particular, we identify two fundamental forces involved in torque generation: electrostatic and steric. We propose that electrostatic forces serve to position the stator, while steric forces comprise the actual 'power stroke'. Specifically, we predict that ion-induced conformational changes about a proline 'hinge' residue in an $\\alpha$-helix of the stator are directly responsible for generating the power stroke. Our model predictions f...
Riettini, A. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires
1964-10-15
After a theoretical study on the slowing down of a centrifugal pump, the motion equations have been checked by means of experimental tests. In order to have important slowing down times (which is the case of the cooling pumps of a research reactor) it is necessary to add a fly-wheel. To prevent troubles when starting, a block pump-fly-wheel with clutch under controlled torque was developed. It is so possible to start the fly-wheel progressively without increasing too much power of the driving motor. (author) [French] Apres une etude theorique sur le mouvement de ralentissement d'une pompe centrifuge, les equations du mouvement ont ete verifiees par des essais pratiques. Pour obtenir des temps de ralentissement importants (cas des pompes de refrigeration d'un reacteur de recherche) il est necessaire d'y adjoindre un volant d'inertie. Pour eviter les inconvenients au demarrage, on a etudie un ensemble pompe-volant avec embrayage sous couple controle. Cette solution permet de lancer progressivement le volant sans augmentation appreciable de la puissance du moteur d'entrainement. (auteur)
Drag Torque Prediction Model for the Wet Clutches
HU Jibin; PENG Zengxiong; YUAN Shihua
2009-01-01
Reduction of drag torque in disengaged wet clutch is one of important potentials for vehicle transmission improvement. The flow of the oil film in clutch clearance is investigated. A three-dimension Navier-Stokes(N-S) equation based on laminar flow is presented to model the drag torque. Pressure and speed distribution in radial and circumferential directions are deduced. The theoretical analysis reveals that oil flow acceleration in radial direction caused by centrifugal force is the key reason for the shrinking of oil film as constant feeding flow rate. The peak drag torque occurs at the beginning of oil film shrinking. A variable is introduced to describe effective oil film area and drag torque after oil film shrinking is well evaluated with the variable. Under the working condition, tests were made to obtain drag torque curves at different clutch speed and oil viscosity. The tests confirm that simulation results agree with test data. The model performs well in the prediction of drag torque and lays a theoretical foundation to reduce it.
He HAO; Wei-zhong FEI; Dong-min MIAO; Meng-jia JIN; Jian-xin SHEN
2016-01-01
In this study, we investigated the torque characteristics of large low-speed direct-drive permanent magnet synchronous generators with stator radial ventilating air ducts for offshore wind power applications. Magnet shape optimization was used fi rst to improve the torque characteristics using two-dimensional fi nite element analysis (FEA) in a permanent magnet synchronous generator with a common stator. The rotor step skewing technique was then employed to suppress the impacts of mechanical tolerances and defects, which further improved the torque quality of the machine. Comprehensive three-dimensional FEA was used to evaluate accurately the overall effects of stator radial ventilating air ducts and rotor step skewing on torque features. The infl uences of the radial ventilating ducts in the stator on torque characteristics, such as torque pulsation and average torque in the machine with and without rotor step skewing techniques, were comprehensively investigated using three-dimensional FEA. The results showed that stator radial ventilating air ducts could not only reduce the average torque but also increase the torque ripple in the machine. Furthermore, the torque ripple of the machine under certain load conditions may even be increased by rotor step skewing despite a reduction in cogging torque.
Cryptanalysis and improvement of controlled secure direct communication
Kao Shih-Hung; Hwang Tzonelih
2013-01-01
This paper points out that,due to a flaw in the sender's encoding,the receiver in Gao et al.'s controlled quantum secret direct communication (CQSDC) protocol [Chin.Phys.14 (2005),No.5,p.893] can reveal the whole secret message without permission from the controller.An improvement is proposed to avoid this flaw.
A Direct Feedback Control Based on Fuzzy Recurrent Neural Network
李明; 马小平
2002-01-01
A direct feedback control system based on fuzzy-recurrent neural network is proposed, and a method of training weights of fuzzy-recurrent neural network was designed by applying modified contract mapping genetic algorithm. Computer simul ation results indicate that fuzzy-recurrent neural network controller has perfect dynamic and static performances .
Motor Controlled Rotating Base for Directional Submarine Antennas
2012-09-28
steel gear 172 that is attached to the rotating platform 150. [0044] Suitable motors include, but are not limited to, a brushless DC motor that...parts. Different motors and different gear heads may be used to provide different torques and operating speeds. A different model pin 26
Bo Long
2013-12-01
Full Text Available Regenerative braking provides an effective way of extending the driving range of battery powered electric vehicles (EVs. This paper analyzes the equivalent power circuit and operation principles of an EV using regenerative braking control technology. During the braking period, the switching sequence of the power converter is controlled to inverse the output torque of the three-phase brushless direct-current (DC motor, so that the braking energy can be returned to the battery. Compared with the presented methods, this technology can achieve several goals: energy recovery, electric braking, ultra-quiet braking and extending the driving range. Merits and drawbacks of different braking control strategy are further elaborated. State-space model of the EVs under energy-regenerative braking operation is established, considering that parameter variations are unavoidable due to temperature change, measured error, un-modeled dynamics, external disturbance and time-varying system parameters, a sliding mode robust controller (SMRC is designed and implemented. Phase current and DC-link voltage are selected as the state variables, respectively. The corresponding control law is also provided. The proposed control scheme is compared with a conventional proportional-integral (PI controller. A laboratory EV for experiment is setup to verify the proposed scheme. Experimental results show that the drive range of EVs can be improved about 17% using the proposed controller with energy-regeneration control.
Mcdougal, A. R.; Norman, R. M. (Inventor)
1976-01-01
A gear head wrench particularly suited for use in applying torque to bolts without transferring torsional stress to bolt-receiving structures is introduced. The wrench is characterized by a coupling including a socket, for connecting a bolt head with a torque multiplying gear train, provided within a housing having an annulus concentrically related to the socket and adapted to be coupled with a spacer interposed between the bolt head and the juxtaposed surface of the bolt-receiving structure for applying a balancing counter-torque to the spacer as torque is applied to the bolt head whereby the bolt-receiving structure is substantially isolated from torsional stress. As a result of the foregoing, the operator of the wrench is substantially isolated from any forces which may be imposed.
Planet migration and magnetic torques
Strugarek, A.; Brun, A. S.; Matt, S. P.; Reville, V.
2016-10-01
The possibility that magnetic torques may participate in close-in planet migration has recently been postulated. We develop three dimensional global models of magnetic star-planet interaction under the ideal magnetohydrodynamic (MHD) approximation to explore the impact of magnetic topology on the development of magnetic torques. We conduct twin numerical experiments in which only the magnetic topology of the interaction is altered. We find that magnetic torques can vary by roughly an order of magnitude when varying the magnetic topology from an aligned case to an anti-aligned case. Provided that the stellar magnetic field is strong enough, we find that magnetic migration time scales can be as fast as ~100 Myr. Hence, our model supports the idea that magnetic torques may participate in planet migration for some close-in star-planet systems.
Direct Model Reference Adaptive Control for a Magnetic Bearing
Durling, Mike [Rensselaer Polytechnic Inst., Troy, NY (United States)
1999-11-01
A Direct Model Reference Adaptive Controller (DMRAC) is applied to a magnetic bearing test stand. The bearing of interest is the MBC 500 Magnetic Bearing System manufactured by Magnetic Moments, LLC. The bearing model is presented in state space form and the system transfer function is measured directly using a closed-loop swept sine technique. Next, the bearing models are used to design a phase-lead controller, notch filter and then a DMRAC. The controllers are tuned in simulations and finally are implemented using a combination of MATLAB, SIMULINK and dSPACE. The results show a successful implementation of a DMRAC on the magnetic bearing hardware.
14 CFR 27.361 - Engine torque.
2010-01-01
... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Engine torque. 27.361 Section 27.361... STANDARDS: NORMAL CATEGORY ROTORCRAFT Strength Requirements Flight Loads § 27.361 Engine torque. (a) For turbine engines, the limit torque may not be less than the highest of— (1) The mean torque for...
李瑞; 王明艳
2013-01-01
Extra torque existing in the motor drive load simulator influences the load precision and system stability. Aiming at the problem,based on the work principle and structure,the model of the load system was built and the structure compensation unit was designed. The limitations of the conventional compensation methods were analyzed,and an improved compensation method of structure invariance was proposed. The compound control method was used to design the entire control system. The simulation results indicate using the method,the extra torque can be reduced greatly. It has some feasibility in engineering.% 电动负载模拟器存在多余力矩，且严重影响加载精度和系统的稳定性。针对此问题，在分析加载系统基本结构和原理的基础上，建立加载系统模型，设计结构补偿环节；分析常规补偿方法的局限性，提出改进的结构不变性补偿方法，并用复合控制方法来设计控制系统。仿真结果表明：此方法能够大幅度消除多余力矩，且在工程中有一定的可行性。
Beyond Control Panels: Direct Manipulation for Visual Analytics
Endert, Alexander; Bradel, Lauren; North, Chris
2013-07-19
Information Visualization strives to provide visual representations through which users can think about and gain insight into information. By leveraging the visual and cognitive systems of humans, complex relationships and phenomena occurring within datasets can be uncovered by exploring information visually. Interaction metaphors for such visualizations are designed to enable users direct control over the filters, queries, and other parameters controlling how the data is visually represented. Through the evolution of information visualization, more complex mathematical and data analytic models are being used to visualize relationships and patterns in data – creating the field of Visual Analytics. However, the expectations for how users interact with these visualizations has remained largely unchanged – focused primarily on the direct manipulation of parameters of the underlying mathematical models. In this article we present an opportunity to evolve the methodology for user interaction from the direct manipulation of parameters through visual control panels, to interactions designed specifically for visual analytic systems. Instead of focusing on traditional direct manipulation of mathematical parameters, the evolution of the field can be realized through direct manipulation within the visual representation – where users can not only gain insight, but also interact. This article describes future directions and research challenges that fundamentally change the meaning of direct manipulation with regards to visual analytics, advancing the Science of Interaction.
Modeling Grain Alignment by Radiative Torques and Hydrogen Formation Torques in Reflection Nebula
Hoang, Thiem; Andersson, B-G
2014-01-01
Reflection nebulae--dense cores--illuminated by surrounding stars offer a unique opportunity to directly test our quantitative model of grain alignment based on radiative torques (RATs) and to explore new effects arising from additional torques. In this paper, we first perform detailed modeling of grain alignment by RATs for the IC 63 reflection nebula illuminated both by a nearby $\\gamma$ Cas star and the diffuse interstellar radiation field. We calculate linear polarization $p$ of background stars by radiatively aligned grains and explore the variation of fractional polarization (p/A$_V)$ with visual extinction $A_{V}$ across the cloud. We show that the variation of $p/A_{V}$ from the surface of the dayside toward the IC 63 center can be described by a power law $p/A_{V}\\propto A_{V}^{\\eta}$, having a shallow slope $\\eta \\sim- 0.1$ for $A_{V} 4$. We then consider the effects of additional torques due to H$_{2}$ formation and model grain alignment by joint action of RATs and H$_2$ torques. We find that p/A$_...
Gunabalan, Ramachandiran; Padmanaban, Sanjeevikumar; Blaabjerg, Frede
2015-01-01
Sensorless-based direct vector control techniques are widely used for three-phase induction motor drive, whereas in case of multiple-motor control, it becomes intensively complicated and very few research articles in support to industrial applications were found. A straight-forward direct vector...... control with sensorless operation for parallel connected two similar-rated induction motors driven by single three-phase inverter is proposed and verified numerically by simulation software test under balanced and unbalanced conditions. The proposed control algorithm adapts the natural observer...... to estimate the rotor speed, rotor flux, and load torque of both motors. Simulation results along with theoretical background provided in this paper confirm the feasibility of operation of the ac motors and proves reliability for industrial applications....
Control of directional change after mechanical stimulation in Drosophila
Zhou Yating
2012-10-01
Full Text Available Abstract Background Proper adjustment of moving direction after external mechanical stimulation is essential for animals to avoid danger (e.g. predators, and thus is vital for survival. This process involves sensory inputs, central processing and motor outputs. Recent studies have made considerable progress in identifying mechanosensitive neurons and mechanosensation receptor proteins. Our understandings of molecular and cellular mechanisms that link mechanosensation with the changes in moving direction, however, remain limited. Results In this study, we investigate the control of movement adjustment in Drosophila. In response to gentle touch at the anterior segments, Drosophila larvae reorient and select a new direction for forward movement. The extent of change in moving direction is correlated with the intensity of tactile stimuli. Sensation of gentle touch requires chordotonal organs and class IV da neurons. Genetic analysis indicates an important role for the evolutionarily conserved immunoglobulin (Ig superfamily protein Turtle (Tutl to regulate touch-initiated directional change. Tutl is required specifically in post-mitotic neurons at larval stage after the completion of embryonic development. Circuit breaking analysis identified a small subset of Tutl-positive neurons that are involved in the adjustment of moving direction. Conclusion We identify Tutl and a small subset of CNS neurons in modulating directional change in response to gentle touch. This study presents an excellent starting point for further dissection of molecular and cellular mechanisms controlling directional adjustment after mechanical stimulation.
Hierarchical cooperative control for multiagent systems with switching directed topologies.
Hu, Jianqiang; Cao, Jinde
2015-10-01
The hierarchical cooperative control problem is concerned for a two-layer networked multiagent system under switching directed topologies. The group cooperative objective is to achieve finite-time formation control for the upper layer of leaders and containment control for the lower layer of followers. Two kinds of cooperative strategies, including centralized-distributed control and distributed-distributed control, are proposed for two types of switching laws: 1) random switching law with the dwell time and 2) Markov switching law with stationary distribution. Utilizing the state transition matrix methods and matrix measure techniques, some sufficient conditions are derived for asymptotical containment control and exponential almost sure containment control, respectively. Finally, some numerical examples are provided to demonstrate the effectiveness of the proposed control schemes.
Thruster direction controlling of assembled spacecraft based on gimbal suspension
Hongliang Xu; Hai Huang
2016-01-01
The attitude control system design and its control effect are affected considerably by the mass-property pa-rameters of the spacecraft. In the mission of on-orbit servicing, as fuel is expended, or the payloads are added or removed, the center of mass wil be changed in certain axe; conse-quently, some thrusters' directions are deviated from the center of mass (CM) in certain plane. The CM of assembled spacecraft estimation and thruster direction control are studied. Firstly, the attitude dynamics of the assembled spacecraft is established based on the Newton-Euler method. Secondly, the estimation can be identified by the least recursive squares algorithm. Then, a scheme to control the thrusters’ directions is proposed. By using the gimbal instaled at the end of the boom, the angle of the thruster is controled by driving the gimbal; therefore, thrusters can be directed to the CM again. Finaly, numerical simulations are used to verify this scheme. Results of the numerical simulations clearly show that this control scheme is rational and feasible.
无
1999-01-01
Directional solidification continuous casting (DSCC) process is a new manufacturing technology for metal- lic materials which combines advantages of both directional solidification technology and continuous casting technolo- gy. Unlimited long shaped metal with directionally solidifying microstructure can be produced by this process. It is experimentally shown that controlling condition of stable and continuous growth of single crystal structure means the precise control of the location of the S/L interface, which is affected and determined by seven process parameters. Moreover, these parameters are also interacted each other, so the disturbance of any parameters may cause the fail- ure of controlling of S/L interface. In this paper, on the basis of analyzing the forming conditions of continuously di- rectional microstructures in DSCC process, the control model of DSCC procedure by neural network control (NNC) method was proposed and discussed. Combining with the experiments, we first used the computer to simulate the effects of the solidification parameters on destination control variable (S/L interface) and the interactions among these parameters during DSCC procedure. Secondly many training samples necessary for neural network calculation can be obtained through the simulation. Moreover, these samples are inputted into neural network software (NNs) and trained, then the control model can be built up.
Data-Driven Predictive Direct Load Control of Refrigeration Systems
Shafiei, Seyed Ehsan; Knudsen, Torben; Wisniewski, Rafal
2015-01-01
A predictive control using subspace identification is applied for the smart grid integration of refrigeration systems under a direct load control scheme. A realistic demand response scenario based on regulation of the electrical power consumption is considered. A receding horizon optimal control...... is proposed to fulfil two important objectives: to secure high coefficient of performance and to participate in power consumption management. Moreover, a new method for design of input signals for system identification is put forward. The control method is fully data driven without an explicit use of model...
Nonlinear Direct Robust Adaptive Control Using Lyapunov Method
Chunbo Xiu
2013-07-01
Full Text Available The problem of robust adaptive stabilization of a class of multi-input nonlinear systems with arbitrary unknown parameters and unknown structure of bounded variation have been considered. By employing the direct adaptive and control Lyapunov function method, a robust adaptive controller is designed to complete the globally adaptive stability of the system states. By employing our result, a kind of nonlinear system is analyzed, the concrete form of the control law is given and the meaningful quadratic control Lyapunov function for the system is constructed. Simulation of parallel manipulator is provided to illustrate the effectiveness of the proposed method.
Controlled Directional Growth of TiO2 Nanotubes
In, Su-il; Hou, Yidong; Abrams, Billie
2010-01-01
We demonstrate how the anodization direction and growth rate of vertically aligned, highly ordered TiO2 nanotube (NT) arrays can be controlled and manipulated by the local concentration of O-2 in the electrolyte. This leads to the growth of highly active TiO2 NT arrays directly on nonconducting...... substrates in a single step. By controlling the oxygen concentration, the electrical contact to the titanium film can be preserved until the entire film is anodized. This approach to growing transparent TiO2 NT films yields possibilities for using glass without any transparent conducting oxide coating...
Angular dependence of spin-orbit spin-transfer torques
Lee, Ki-Seung
2015-04-06
In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.
Robust direct adaptive fuzzy control for nonlinear MIMO systems
ZHANG Huaguang; ZHANG Mingjun
2006-01-01
For a class of nonlinear multi-input multi-output systems with uncertainty, a robust direct adaptive fuzzy control scheme was proposed. The feedback control law and adaptive law for parameters were derived based on Lyapunov design approach. The overall control scheme can guarantee that the tracking error converges in the small neighborhood of origin, and all signals of the closed-loop system are uniformly bounded. The main advantage of the proposed control scheme is that in each subsystem only one parameter vector needs to be adjusted on-line in the adaptive mechanism, and so the on-line computing burden is reduced. In addition, the proposed control scheme is a smooth control with no chattering phenomena. A simulation example was proposed to demonstrate the effectiveness of the proposed control algorithm.
Negahban, Hossein; Moradi-Bousari, Aida; Naghibi, Saeed; Sarrafzadeh, Javad; Shaterzadeh-Yazdi, Mohammad-Jafar; Goharpey, Shahin; Etemadi, Malihe; Mazaheri, Masood; Feizi, Awat
2013-01-01
Purpose The aim of this study was to investigate eccentric torque production capacity of the ankle, knee and hip muscle groups in patients with unilateral chronic ankle instability (CAI) as compared to healthy matched controls. Methods In this case-control study, 40 participants (20 with CAI and 20 controls) were recruited based on convenient non-probability sampling. The average peak torque to body weight (APT/BW) ratio of reciprocal eccentric contraction of ankle dorsi flexor/plantar flexor, ankle evertor/invertor, knee flexor/extensor, hip flexor/extensor and hip abductor/adductor was determined using an isokinetic dynamometer. All subjects participated in two separate sessions with a rest interval of 48 to 72 hours. In each testing session, the torque production capacity of the ankle, knee, and hip muscle groups of only one lower limb was measured. At first, 3 repetitions of maximal eccentric-eccentric contraction were performed for the reciprocal muscles of a joint in a given movement direction. Then, the same procedure of practice and testing trials was repeated for the next randomly-ordered muscle group or joint of the same limb. Results There was no significant interaction of group (CAI and healthy controls) by limb (injured and non-injured) for any muscle groups. Main effect of limb was not significant. Main effect of group was only significant for eccentric torque production capacity of ankle dorsi flexor and hip flexor muscle groups. The APT/BW ratio of these muscles was significantly lower in the CAI group than the healthy controls (P<0.05). Conclusion CAI is associated with eccentric strength deficit of ankle dorsi flexor and hip flexor muscles as indicated by reduction in torque production capacity of these muscles compared to healthy controls. This strength deficit appeared to exist in both the injured and non-injured limbs of the patients. PMID:23802057
Seddon, Jon; Pechev, Alexandre
2009-01-01
This paper proposes a new concept for attitude actuation for small satellites that uses active magnetic bearings to support and tilt a spinning rotor to provide 3-axis attitude control of the satellite using a single actuator. A controlled 3D motion in the spinning rotor provides a conventional torque output about the momentum axis and a gyroscopic torque output about any direction in the plane normal to the spinning axis. Therefore, a single tilting momentum-wheel can generate torque along t...
Ibrahim Mohd Alsofyani
2015-02-01
Full Text Available In this paper, two kinds of observers are proposed to investigate torque estimation. The first one is based on a voltage model represented with a low-pass filter (LPF; which is normally used as a replacement for a pure integrator to avoid integration drift problem due to dc offset or measurement error. The second estimator used is an extended Kalman filter (EKF as a current model, which puts into account all noise problems. Both estimation algorithms are investigated during the steady and transient states, tested under light load, and then compared with the measured mechanical torque. In all conditions, the torque estimation error for EKF has remained within a narrow error band and yielded minimum torque ripples, which motivate the use of the EKF estimation algorithm in high performance control drives of IMs for achieving high dynamic performance.
卢秉娟; 姬宣德; 葛运旺
2014-01-01
针对异步电动机传统直接转矩控制(BASIC-DTC)转矩磁链脉动大、开关频率不固定和空间矢量调制直接转矩控制(SVM-DTC)系统结构复杂、调节器参数设计困难的缺点,提出了一种基于转矩角控制的SVM-DTC方法.该方法简化了系统结构,降低了调节器参数设计的难度;与BASIC-DTC相比,该方法减小了转矩磁链脉动,克服了开关频率不固定的缺点,而且获得了与BASIC-DTC一样的动态响应.
Resonant excitation of coupled skyrmions by spin-transfer torque
Dai, Y. Y.; Wang, H.; Yang, T.; Zhang, Z. D.
2016-12-01
Resonant excitations of coupled skyrmions in Co/Ru/Co nanodisks activated by spin-transfer torque (STT) have been studied by micromagnetic simulations. It is found that STT is an effective method to manipulate skyrmion dynamics. Unlike the dynamics driven by a microwave field, two skyrmions with opposite chiralities move synchronously in the same direction when they are driven by STT, which makes it easier to observe the dynamics of coupled skyrmions in experiments. Resonant excitations of coupled skyrmions can be controlled by changing the frequency or amplitude ratio of a dual-frequency alternating current (AC). In addition, the magnetostatic interaction between the two skyrmions plays an important role in the dynamics of coupled skyrmions.
Low torque hydrodynamic lip geometry for rotary seals
Dietle, Lannie L.; Schroeder, John E.
2015-07-21
A hydrodynamically lubricating geometry for the generally circular dynamic sealing lip of rotary seals that are employed to partition a lubricant from an environment. The dynamic sealing lip is provided for establishing compressed sealing engagement with a relatively rotatable surface, and for wedging a film of lubricating fluid into the interface between the dynamic sealing lip and the relatively rotatable surface in response to relative rotation that may occur in the clockwise or the counter-clockwise direction. A wave form incorporating an elongated dimple provides the gradual convergence, efficient impingement angle, and gradual interfacial contact pressure rise that are conducive to efficient hydrodynamic wedging. Skewed elevated contact pressure zones produced by compression edge effects provide for controlled lubricant movement within the dynamic sealing interface between the seal and the relatively rotatable surface, producing enhanced lubrication and low running torque.
Global Observer-Based Attitude Controller Using Direct Inertial Measurements
Saâdi Bouhired
2014-04-01
Full Text Available In this work, we address the problem of global attitude control using direct inertial measurements. When using direct inertial measurement to observe the rigid body attitude, it is shown that due to a geometrical obstruction, it is impossible to achieve global asymptotic stability. In fact, for a particular initial condition the tracking error quaternion converges to a pure imaginary quaternion formed by an eigenvector of a characteristic matrix related to the inertial constant and known vectors. Our proposition consists of adding a dynamic signal to force the rigid body to escape from such a situation. The proposed observer-based controller is synthesized based on a single Lyapunov function and a stability analysis shows that the controller stabilizes globally and asymptotically the rigid body attitude at the desired one. The effectiveness of the proposed observer-based controller is confirmed by simulation results.
赵治国; 王琪; 陈海军; 刁威振
2013-01-01
A torque coordinating optimalcontrol strategy was developed using different driving intentions in different shifting process phases for a six-speed Dry Dual-Clutch-Transmission (DDCT) of a self-developed car. A simulation model was set up on the Matlab/Simulink software platform and then used to simulate the control strategy for DDCT shifting process. The sub-divided phases included the quadratic optimal control adopted in torque phase;the ignition parameters and fuel supply controlin inertia phase;the control factor mapping method, which relfects driving intension, both in micro-slipping phase and in demanded torque switching phase. The results show that shift jerks are within-2 m/s3 while the total frictional energy losses are within 2 kJ in shift process. Therefore, this control strategy relfects driving intentions and meets the demand of shift quality.%对于某一自主开发汽车的六速干式双离合器变速器（DDCT），提出了对不同驾驶意图、分阶段采取不同措施的转矩协调最优控制策略：在转矩相阶段，运用二次型最优控制确定了离合器转矩变化率；在惯性相阶段，采用发动机点火参数与燃油供给调节控制以缩短惯性相时间；在微滑摩阶段及需求转矩切换阶段，建立了体现驾驶意图的控制因子映射。并在Matlab/Simulink软件平台上，搭建了DDCT换挡过程模型，进行仿真试验。结果表明：换挡过程中的换挡冲击在-2 m/s3以内，产生的总滑摩功在2 kJ以内；因而，该控制策略能体现驾驶员的换挡意图，且满足换挡品质需求。
Stability analysis of direct current control in current source rectifier
Lu, Dapeng; Wang, Xiongfei; Blaabjerg, Frede
2017-01-01
Current source rectifier with high switching frequency has a great potential for improving the power efficiency and power density in ac-dc power conversion. This paper analyzes the stability of direct current control based on the time delay effect. Small signal model including dynamic behaviors...... of dc link is developed to identify the control plants of grid ac current control and dc current control. Analysis on the poles and zeros under dq frame is carried out. Base on this model, it turns out that the phase lag caused by the time delay can stabilized the grid ac current control while reduces...... the stable region for dc current control. Simulation and experimental results are presented to validate the theoretical analysis....