Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation
Directory of Open Access Journals (Sweden)
MILOUD, Y.
2010-08-01
Full Text Available This paper proposes the space vector pulse width modulation (SVPWM control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load�s disturbance of PWM rectifiers are both improved. The simulation result shows feasibility of this strategy.
Research on Passivity Based Controller of Three Phase Voltage Source PWM Rectifier
Directory of Open Access Journals (Sweden)
Yin Hongren
2012-09-01
Full Text Available Euler-Lagrange (EL model of voltage source PWM rectifier is set up based on its model in synchronous dq coordinates. Passivity based controller is designed on the basis of passivity and EL model of voltage source PWM rectifier. Three switching function are educed by passivity based controller. A switching function is only realized in engineering consequently. Voltage source PWM rectifier using passivity based controller has many advantages, such as simpler structure, low total harmonic distortion, and good disturbance rejection performance. Passivity based control law is proved feasible by simulink simulation.
A single leg switched PWM method for three-phase H-Bridge Voltage Source Converters
DEFF Research Database (Denmark)
Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig;
2009-01-01
This paper proposes a single leg switched or a hybrid PWM (HPWM) method for three-phase three-level H-Bridge Voltage Source Converters (3L-HB-VSCs). By means of the proposed modulation, a 3L-HB-VSC can generate the same output as a three-level neutral point clamped (3L-NPC) VSC with phase...... disposition (PD) PWM provided that the outputs of 3L-HBVSC are isolated by transformers or connected to open winding machines. Thus, the proposed method is called PD-HPWM. Moreover, it is emphasized that 3L-HB-VSC with HPWM utilizes its switches similar to 3L-NPC-VSC. Compared to 3L-NPC-VSCs, 3L......-HB-VSCs (without neutral point clamping diodes) have simpler, more modular, and more reliable 2L circuit structure. Therefore, this method encourages the use of 3L-HB-VSCs in the applications utilizing transformers such as grid-side converters of multi-MW wind turbines. The proposed PWM method's performance...
三相电压型PWM整流器自抗扰控制%Active Disturbance Rejection Control of Three-Phase Voltage Source PWM Rectifiers
Institute of Scientific and Technical Information of China (English)
刘子建; 吴敏; 王春生; 桂武鸣; 陈鑫
2011-01-01
Based on the nonlinear characteristic of three-phase voltage source PWM rectifiers, a nonlinear control strategy is proposed. The voltage and current controllers are designed by using active disturbance rejection control (ADRC) technique, and then, the controllers have the advantage of robustness. The load disturbance is compensated by the voltage controller, which effectively removes the static tracking error of the output direct current (DC) voltage, which is caused by the disturbance. The switching signals of the three-phase voltage source PWM rectifiers are generated by space vector pulse width modulation (PWM) method. Simulation results show the effectiveness of the presented control strategy.%针对三相电压型PWM整流器本身的非线性特点,提出一种非线性控制策略.采用自抗扰控制技术设计了电压和电流控制器,具有鲁棒性强的特点.通过电压控制器对负载扰动进行补偿,消除了负载扰动带来的输出直流电压稳态跟踪误差.三相电压型PWM整流器的开关信号利用空间矢量脉宽调制方法生成.仿真结果表明,本文所提控制策略是有效的,
Institute of Scientific and Technical Information of China (English)
毛鸿; 吴兆麟; 王毅; 刘树林
2001-01-01
三相电压型PWM整流器有间接电流控制和直接电流控制两种方式，两种控制方式各有优点。根据三相电压型PWM整流器的高频动态数学模型，提出了基于开关函数检测的无电流传感器控制策略。该控制策略兼有间接电流控制结构简单，成本低和直接电流控制动态响应速度快、限流容易、控制精度高等优点。实验结果验证了控制策略的可行性。%There are two basic control schemes for three-phase voltage-source PWM rectifier: the direct current control and indirect current control. The direct current control scheme achieves better dynamic and steady state performance, but its control cost is much higher than the indirect current control. Based on the dynamic high frequency mathematical model of three-phase voltage-source PWM rectifier, a novel sensorless current control strategy is presented for the first time, which is implemented by estimating the variables of the three-phase input current via other variables. The control strategy has super characters such as simple structure, low cost, good dynamic and steady state performance and ability to limit the input currents. A simple hardware implementation is proposed and the good experimental results are reported to confirm the quality of the presented strategy.
Institute of Scientific and Technical Information of China (English)
杨达亮; 卢子广; 杭乃善; 李国进
2011-01-01
建立三相电压型脉宽调制（pulse width modulation，PWM）整流器在不同坐标系下的数学模型，分析直接功率控制（direct power control，DPC）的工作原理。针对直接功率控制中开关频率变化问题，通过对PWM整流器瞬时功率分析推导，提出一种内环直接采用电流控制的新型准定频直接功率控制策略。仿真验证了算法的可行性。采用PM300DVAl20智能功率模块，设计50kVA的三相电压型PWM整流器控制实验，在10kHz、5us的开关频率下获得良好的实验结果。实验结果表明，所提方法实现单位功率因数运行，与现行的DPC—SVM定频控制方法相比，具有更好的动静态响应性能。%This paper established the three-phase voltage-source pulse width modulation （PWM） rectifier mathematical models in different coordinate systems and analyzed the principle of direct power control （DPC）. To alleviate the problem of variable switching frequency, a novel quasi DPC control strategy with current loop was represented through the analysis of PWM rectifier instantaneous power. The novel control strategy was proved feasible by the Matlab/Simulink simulation results. The 50kVA three-phase voltage-source PWM rectifier control experiment system was designed using PM300DVA120 intelligent power module （IPM）, the excellent experiment results were given at the 10kHz switching frequency with 5μs dead time. The experimental results indicate that the PWM rectifier system achieves unity power factor operation and has better performance of dynamic and static response compared to the present space vector modulation （SVM） DPC fixed-frequency control method.
Institute of Scientific and Technical Information of China (English)
李武云
2014-01-01
The improved space vector hysteresis control was introduced for the disadvantage of poor current tracking caused by the traditional control strategy in the three-phase voltage source PWM rectifier. The improved strategy choose the hysteresis loop width and the switch state through the judgment of the AC error current vector modulus, and the selection principle of the switch state was provided in order to reduce the switching losses. Final y, the simulation model was established under matlab/simulink to compare AC current quality between the traditional and the improved control strategies, the simulation results further demonstrated the superiority of the improved control scheme.%提出了一种改进的滞环空间矢量控制，用于解决三相电压型PWM整流器采用传统滞环空间矢量控制时，电流跟踪效果不佳的问题。改进后的控制策略通过对交流侧误差电流矢量模值大小判断后，选择滞环环宽和对应的开关状态，同时总结出最佳的开关状态选择原则，以最大限度地低开关损耗，提高系统响应速度。最后在matlab/simulink下建立系统的仿真模型，通过对改进前后两种控制策略下交流侧电流质量的对比，进一步验证了改进后控制策略的优越性。
Institute of Scientific and Technical Information of China (English)
王恩德; 黄声华
2012-01-01
同步旋转d-q坐标系下的电压、电流双闭环控制，广泛应用于三相电压型PWM整流器。该方案结构简单，比较适合基于数字处理芯片的数字控制系统。由于交流侧电感工艺存在差异，且当电流很大电感饱和时，电感值也会有变化，实际控制系统往往忽略掉耦合项；而电压外环的非线性也使得控制系统的性能提升受到限制。提出一种新的电压电流双闭环控制策略，其中电流内环借鉴合成矢量的思想，提出同步旋转d-q坐标系下无电感￡参数的电流解耦控制方法：电压外环采用电压平方为控制量实现线性化的间接电压控制。仿真与实验结果均验证了所提方法的正确性和有效性。%The double closed loop control strategy, which is composed of inner current loop and outer voltage loop in the d-q synchronous frame, is a relatively common control strategy of the three-phase voltage-sourced PWM rectifier. This strategy is suitable for the digital control system with the digital signal processor （DSP）, because of its simple structure. The decoupling part is often ignored without the exact value of the boost inductance. And the nonlinear outer voltage loop is also the limit to improve the control performance. This paper proposed a novel double closed loop control strategy, which consists of decoupling current controller without exact value of the boost inductance in d-q synchronous frame, and the outer voltage linear control strategy with the control amount of the square of the voltage. Both the simulation analysis and experimental results demonstrate the validity of the proposed method and the feasibility of the control strategy.
Institute of Scientific and Technical Information of China (English)
罗德荣; 姬小豪; 黄晟; 廖武
2014-01-01
Mathematical modeling of voltage source PWM filter is conducted and a predictive power model under two-phase rest frame is established, on this basis an optimal model predictive direct power control (MPDPC) strategy is proposed. In the proposed control strategy the voltage vector in power supply system is taken as the basic control vector and utilizing power directive model and minimum power error principle the formula of objective control voltage vector is obtained, then combining with space vector PWM modulation(SVPWM) the model predictive direct power control is implemented. Meanwhile, considering the step delay in actual control systems a delay compensation scheme is designed. Besides, the repetitive control is led in to optimize the active and reactive power in each sampling cycle. The feasibility of the proposed control method is validated by results of simulation and experiments.%对电压型PWM整流器进行了数学建模，然后在两相静止坐标系下建立了预测功率模型，在此基础上提出了优化的模型预测直接功率控制(model predictive direct power control，MPDPC)策略。该方法用电网电压矢量作为基本控制矢量，利用功率预测模型和功率误差最小原则，得出目标控制电压矢量公式，结合空间矢量脉宽调制实现模型预测功率控制。同时针对实际系统中的一步延迟设计了延时补偿方案。此外，在系统中引入重复控制对每个采样周期系统的有功、无功功率进行优化。仿真和实验验证了表明所提出的方法的可行性。
Abolfazl Halavei Niasar; Ehsan Boloor Kashani
2013-01-01
Induction motors offer many advantages tools, and therefore are becoming very popular industrially and commercially. This paper presents the implementation of Xmega microcontroller based PWM inverter controlled of four-switch three phase voltage source inverter (FSTPI) fed induction motor 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 addition to less complexity of contro...
Directory of Open Access Journals (Sweden)
Zulkifilie Bin Ibrahim
2014-03-01
Full Text Available Pulse width modulation (PWM technique is one of the vital issues for power electronic circuit control. A number of Pulse width modulation (PWM techniques are increasingly applied in many new industrial applications that require superior performance. The most widely applied PWM technique for three-phase voltage source inverters are Sine Pulse Width Modulation (SPWM, Third Harmonic Injection Pulse Width Modulation (THIPWM and Space Vector Pulse Width Modulation (SVPWM. SPWM is the most simple modulation technique that can realize easily in analog circuit. However, it has some drawbacks such as higher total harmonic distortion (THD, lower switching frequency and not capable in over modulation region. THIPWM and SVPWM both provide better THD compared to SPWM. SVPWM shows lower THD in over modulation region and in high frequency application compared to THIPWM. These three techniques are discussed, analyzed and compared in terms of modulation index, switching frequency and inverter input voltage in this paper. The modeling and simulation for all PWM techniques have been done by using MATLAB/SIMULINK and Origin 6.1. From the simulation results, SVPWM shows the best performance and meet IEEE 519 standard of current harmonics level.
Institute of Scientific and Technical Information of China (English)
郜阳; 胡家喜; 郭世明; 陈涛; 刘林曼
2012-01-01
电力电子设备中，诸如二极管、晶闸管等都会带来非线性和谐波电流等问题。三相电压型PWM整流器有输入电流接近正弦、功率因数可控、能量双向流动等特点，采用这种整流器可以解决非线性和谐渡电流问题，需要在电路中加入滤波器。传统纯电感L滤波器的电感值一般比较大，就会出现装置体积大、成本高、系统的动态响应慢等问题。文章采用LCL滤波器代替L滤波器，因LCL滤波器电感取值比L滤波器电感取值小，能够解决传统滤波器所带来的问题。通过Matlab建模仿真，验证了理论分析的正确性。%The problems such as nonlinear and harmonic current etc. are existing in power electronic devices(e.g., diode and thyristor rectifiers ). A solution to avoid mentioned problems is adopted by using the three-phase PWM rectifier which has the characteristics of input current closing to sinusoidal, controllable reactive power and hi-directional power flow capability. We should add filter to the circuit in order to eliminate distortion and harmonious. Because inductance value of traditional L filter with pure inductance is usually large, the problems such as large volume, high cost and slow dynamic response will arise. Traditional L filter is replaced by the LCL filter, on an account of inductor value of LCL filter smaller than the L filter's, which can solve the problems brought by the traditional filter. ThrOugh the Matlab modeling and simulation, the correctness of theory analysis is verified.
Miller, Stephanie Katherine Teixeira
Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage-source
Institute of Scientific and Technical Information of China (English)
侯世英; 张诣
2011-01-01
Aiming at the problems that classic phase-locked loop (PLL) has low response speed and detection accuracy under frequency offset of network voltage conditions, a novel analog signal PLL based on coordinate transformation is proposed, and based on the PLL, the model of three-phase voltage source pulse width modulation (PWM) rectifier is built. The rectifier adopts the modulation method of space vector pulse width modulation(SVPWM). According to the circuit topology of the PWM rectifier, the framework of control strategy is given. Also the circuit topology and working principle of PLL are analyzed. Finally, a simulation is done through the Matlab. Simulation results show that the PLL can track the network frequency so well that it can realize phase locking. And the novel PLL can also achieve phase locking under the condition of frequency drift of three-phase network voltage.%为了解决在电网电压出现频率偏移时,传统锁相环响应速度慢、锁相精度差的问题,提出一种基于坐标变换理论的新型模拟信号锁相环,并建立了基于模拟信号锁相环的三相电压型PWM整流器模型.该整流器采用空间矢量脉宽调制(Space Vector Pulse Width Modulation,SVPWM).在对所提PwM整流器的基本拓扑进行分析的基础上,给出了控制策略框图,并分析了新型锁相环的电路结构和工作原理.通过Matlab对所建模型进行了仿真.仿真结果表明:模拟信号锁相环能够快速跟踪系统频率的变化,实现锁相功能.同时,在三相电网电压频率出现小范围漂移情况下,新型锁相环也能够准确锁相.
Yamada, Hiroaki; Tanaka, Toshihiko; Funabiki, Shigeyuki
This paper proposes a novel method of suppressing the inrush current of transformers. A small-rated voltage-source PWM converter is connected in series to the transformers through a matching transformer. As the connected PWM converter performs a resistor for the source current, no inrush phenomena occurs. The required-ratings of the PWM converter, which performs the damping resistor for the inrush phenomena, is one-four-hundredth as compared to that of the main transformers in single-phase circuits. In three-phase circuits, it is one-nine-hundredth. The basic principle of the proposed method is discussed. Digital computer simulation is implemented to confirm the validity and excellent practicability of the proposed method using the PSCAD/EMTDC. A prototype experimental-model is constructed and tested. The experimental results demonstrate that the proposed method can perfectly suppress the inrush phenomena.
An Integrated Inductor For Parallel Interleaved Three-Phase Voltage Source Converters
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus;
2016-01-01
Three phase Voltage Source Converters (VSCs) are often connected in parallel to realize high current output converter system. The harmonic quality of the resultant switched output voltage can be improved by interleaving the carrier signals of these parallel connected VSCs. As a result, the line...
Shunt PWM advanced var compensators based on voltage source inverters for Facts applications
Energy Technology Data Exchange (ETDEWEB)
Barbosa, Pedro G.; Misaka, Isamu; Watanabe, Edson H. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia
1994-12-31
Increased attention has been given to improving power system operation. This paper presents modeling, analysis and design of reactive shunt power compensators based on PWM-Voltage Source Inverters (Pulse Width Modulation -Voltage Source Inverters). (Pulse Width Modulation - Voltage Source Inverters). The control algorithm is based on new concepts of instantaneous active and reactive power theory. The objective is to show that with a small capacitor in the side of a 3-phase PWM-VSI it is possible to synthesize a variable reactive (capacitive or inductive) device. Design procedures and experimental results are presented. The feasibility of this method was verified by digital simulations and measurements on a small scale model. (author) 9 refs., 12 figs.
Directory of Open Access Journals (Sweden)
Abolfazl Halavei Niasar
2013-02-01
Full Text Available Induction motors offer many advantages tools, and therefore are becoming very popular industrially and commercially. This paper presents the implementation of Xmega microcontroller based PWM inverter controlled of four-switch three phase voltage source inverter (FSTPI fed induction motor 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 addition to less complexity of control algorithms and reduced interface circuits. Simulation and experimental work are carried out and results presented to demonstrate the feasibility of the proposed approach. Simulation is carried out using SIMULINK and in experimental work, a prototype model is built to verify the simulation results. XMEGA microcontroller (XMEGA64A3 is used to generate the PWM pulses with a new algorithm for FSTPI to drive a 5 hp, 3-phase induction motor. Experimental and simulation results show that the proposed drive system provides a fast speed response and good disturbance rejection capability.
Border Collision of Three-Phase Voltage-Source Inverter System with Interacting Loads
Li, Zhen; Liu, Bin; Li, Yining; Wong, Siu-Chung; Liu, Xiangdong; Huang, Yuehui
As a commercial interface, three-phase voltage-source inverters (VSI) are commonly equipped for energy conversion to export DC power from most distributed generation (DG) to the AC utility. Not only do voltage-source converters take charge of converting the power to the loads but support the grid voltage at the point of common connection (PCC) as well, which is dependent on the condition of the grid-connected loads. This paper explores the border collision and its interacting mechanism among the VSI, resistive interacting loads and grids, which manifests as the alternating emergence of the inverting and rectifying operations, where the normal operation is terminated and a new one is assumed. Their mutual effect on the power quality under investigation will cause the circuital stability issue and further deteriorate the voltage regulation capability of VSI by dramatically raising the grid voltage harmonics. It is found in a design-oriented view that the border collision operation will be induced within the unsuitable parameter space with respect to transmission lines of AC grid, resistive loads and internal resistance of VSI. The physical phenomenon is also identified by the theoretical analysis. With numerical simulations for various circuit conditions, the corresponding bifurcation boundaries are collected, where the stability of the system is lost via border collision.
Analysis of Discontinuous Space Vector PWM Techniques for a Seven-Phase Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Mohd. Arif Khan
2012-03-01
Full Text Available This paper presents discontinuous space vector PWM (DPWM techniques for a seven-phase voltage source inverter (VSI. Space vector model of a seven-phase VSI shows that there exist 128 space vectors with different lengths and maps into fourteen sided polygons. A number of possibilities could arise to implement modulation of inverter legs due to large number of available space voltage vectors. Two strategies are adopted here; one utilising large and two middle sets of space vectors to implement discontinuous space vector PWM. Clamping of legs of inverter to either positive or negative dc bus leads to discontinuity in the switching and consequently offers reduced switching loss modulation strategy. A significant reduction in switching losses can be achieved while employing DPWM in a seven-phase VSI. A generalised method is also proposed to realize the DPWM in a seven-phase VSI. Comparison of continuous and discontinuous PWM is presented in terms of switching current ripple. The experimental set-up is illustrated and the experimental results are presented.
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe
2012-01-01
The virtual output impedance loop is known as an effective way to enhance the load sharing stability and quality of droop-controlled parallel inverters. This paper proposes an improved design of virtual output impedance loop for parallel three-phase voltage source inverters. In the approach, a vi...
Directory of Open Access Journals (Sweden)
Ajay Kumar Maurya, Kishore Chahar, Y. K. Chauhan
2013-03-01
Full Text Available This paper presents the analysis of a photovoltaicbases three-phase five level voltage source inverter(VSI supplying induction motor driven waterpump. The VSI uses a unipolar PWM technique forproducing three phase 5 level voltage output andthis output is used to drive three-phase inductionmotor driving a pump load. Multilevel inverters areused for generating AC voltage from several levelsof DC voltages and enhance the performance of thesystem. The proposed system is used to reduce thefiltering requirements and reduce the amplitude ofall harmonics at the output of the inverter. ThePower quality improves by reducing the harmonicslevel. The complete simulation model is simulatedin MATLAB/SIMULINK and validates thetheoretical considerations
Three-Phase Back PWM-PFC Rectifier
Institute of Scientific and Technical Information of China (English)
Yasuyuki Nishida
2005-01-01
A new 3-phase back (or current-source-type) PWM-PFC rectifier is proposed in this paper. The necessity,the advantages and disadvantages of this type PWM rectifier are discussed first.Then,the new power circuit topology and the modulation scheme to eliminate or mitigate the disadvantages and obtain further new advantages of the buck PWM rectifier are introduced.The features of the new rectifier, i.e., high efficiency, simple modulation process, robustness of the line-current modulation for distortion of the utility voltages and DC current ripples have been confirmed through experimental results obtained from a 12kW prototype.
Analysis of Peak-to-Peak Current Ripple Amplitude in Seven-Phase PWM Voltage Source Inverters
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Gabriele Grandi
2013-08-01
Full Text Available Multiphase systems are nowadays considered for various industrial applications. Numerous pulse width modulation (PWM schemes for multiphase voltage source inverters with sinusoidal outputs have been developed, but no detailed analysis of the impact of these modulation schemes on the output peak-to-peak current ripple amplitude has been reported. Determination of current ripple in multiphase PWM voltage source inverters is important for both design and control purposes. This paper gives the complete analysis of the peak-to-peak current ripple distribution over a fundamental period for multiphase inverters, with particular reference to seven-phase VSIs. In particular, peak-to-peak current ripple amplitude is analytically determined as a function of the modulation index, and a simplified expression to get its maximum value is carried out. Although reference is made to the centered symmetrical PWM, being the most simple and effective solution to maximize the DC bus utilization, leading to a nearly-optimal modulation to minimize the RMS of the current ripple, the analysis can be readily extended to either discontinuous or asymmetrical modulations, both carrier-based and space vector PWM. A similar approach can be usefully applied to any phase number. The analytical developments for all different sub-cases are verified by numerical simulations.
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
Power Electronic Transformer based Three-Phase PWM AC Drives
Basu, Kaushik
A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common
Escobar, Gerardo; Ortega, Romeo; Schaft, Arjan J. van der
1998-01-01
In this article, we present a saturating controller to regulate the output voltage load in a three phase Boost type rectifier. The controller only needs the output voltage signal to be implemented. Moreover, by forcing the inductance currents to track desired suitable sinusoidal signals in phase wit
Directory of Open Access Journals (Sweden)
Z.A. Jaffery
2012-10-01
Full Text Available The authors present the design, simulation and analysis of a single phase voltage source inverter using soft switching techniques. The performance of the inverter has been compared in terms of harmonic contents present in output voltage and current. The research works for a PWM inverter along with a LLCC filter has been investigated. This paper also investigated the performance of the same inverter with a feedback controller with a closed loop feedback path to maintain rated output voltage. This work is helpful for the inverter used in application where high quality ac wave is prime requirement
DEFF Research Database (Denmark)
Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi;
2013-01-01
Power electronics based MicroGrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel connected three-phase VSIs are derived. The proposed voltage and current inner control loops and the mat......Power electronics based MicroGrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of parallel connected three-phase VSIs are derived. The proposed voltage and current inner control loops...... and the mathematical models of the VSIs are based on the stationary reference frame. A hierarchical control scheme for the paralleled VSI system is developed comprising two levels. The primary control includes the droop method and the virtual impedance loops, in order to share active and reactive power. The secondary...... control restores the frequency and amplitude deviations produced by the primary control. Also, a synchronization algorithm is presented in order to connect the MicroGrid to the grid. Experimental results are provided to validate the performance and robustness of the parallel VSI system control...
CONTROL TECHNIQUES FOR VARIOUS BIPOLAR PWM STRATEGIES OF THREE PHASE FIVE LEVEL CASCADED INVERTER
Directory of Open Access Journals (Sweden)
C. R. BALAMURUGAN
2015-07-01
Full Text Available This paper presents different types of bipolar Pulse Width Modulation (PWM strategies for the chosen Cascaded MultiLevel Inverter (CMLI. The main purpose of MLI is to use power semiconductor devices of lower voltage ratings to realize high voltage levels at inverter output. Due to their ability to obtain refined output voltage waveforms, reduced Total Harmonic Distortion (THD and reduced EMI problems by reducing the switching dv/dt. In this paper, a three phase CMLI is controlled with Sinusoidal PWM strategy with Phase Disposition PWM (PDPWM, Phase Opposition and Disposition PWM (PODPWM, Alternative Phase Opposition and Disposition PWM (APODPWM, Phase Shift PWM (PSPWM and hybrid modulation strategy and the variation of THD in their outputs are observed by varying the modulation index. Simulations are performed using MATLAB-SIMULINK. It is observed that APODPWM and PSPWM provide output with relatively low distortion. It is also seen that PS, APOD and hybrid PWM are found to perform better since they provide relatively higher fundamental RMS output voltage. From hardware results it is seen that POD PWM provides output with relatively low distortion. It is also observed that PSPWM is found to perform better since it provide relatively higher fundamental RMS output voltage.
Intelligent Optimize Design of LCL Filter for Three-Phase Voltage-Source PWM Rectifier
DEFF Research Database (Denmark)
Sun, Wei; Chen, Zhe; Wu, Xiaojie
2009-01-01
Compared to traditional L filter, a LCL filter is more effective on reducing harmonic distortion at switch frequency. So it is important to choose the LCL filter parameters to achieve good filtering effect. This paper introduces some traditional design methods. Design of a LCL filter by genetic...... algorithm (GA) and particle swam optimization (PSO) are presented in this paper and comparison of the two intelligent optimization. Simulation result and calculate data are provided to prove that intelligent optimization are more effective and simple than traditional methods....
Three Phase Six-Switch PWM Buck Rectifier with Power Factor Improvement
DEFF Research Database (Denmark)
Zafar Ullah Khan, M; Mohsin Naveed, M.; Hussain, Dil Muhammad Akbar
2013-01-01
Conventional Phase Controlled Rectifier injects low order current harmonics into the AC mains. Large size filtering components are required to attenuate these harmonics. In this paper, Three Phase Six-Switch PWM Buck Rectifier[1] is presented which operates at nearly unity power factor and provid...
DEFF Research Database (Denmark)
Vasquez, Juan Carlos; Guerrero, Josep M.; Savaghebi, Mehdi
2011-01-01
and discussed. Experimental results are provided to validate the performance and robustness of the VSIs functionality during Islanded and grid-connected operations, allowing a seamless transition between these modes through control hierarchies by regulating frequency and voltage, main-grid interactivity......Power electronics based microgrids consist of a number of voltage source inverters (VSIs) operating in parallel. In this paper, the modeling, control design, and stability analysis of three-phase VSIs are derived. The proposed voltage and current inner control loops and the mathematical models...... the frequency and amplitude deviations produced by the primary control. And the tertiary control regulates the power flow between the grid and the microgrid. Also, a synchronization algorithm is presented in order to connect the microgrid to the grid. The evaluation of the hierarchical control is presented...
Integrated PWM converter/inverter system feeding three-phase induction motor
Energy Technology Data Exchange (ETDEWEB)
Bayoumi, E.
2001-07-01
The integrated PWM converter/inverter system has the capability of unity power factor, sinusoidal supply current, bi-directional power capabilities and constant dc link voltage. Also, it has the ability to minimize the dc link capacitance. The integrated PWM converter/inverter fed three-phase induction motor consists of two identical PWM converters. One is used to serve as power regulator with unity power factor and constant dc voltage bus, while the other serve as inverter for the induction motor drive. By using the synchronous rotating-frame the current controllers in both the input and the output of the integrated system are characterized by fast current response and low harmonic distortion. The dc link is the intermediate stage between the PWM converter and the PWM inverter. It mainly consists of aluminium electrolytic capacitors, which are normally installed in the system as the energy storage element, but in some applications, such as high power voltage motor drives, the electrolytic capacitor has several drawbacks from the viewpoints of size, weight, cost and reliability. Due to continuous outgassing, the properties of the electrolytic capacitor deteriorate gradually (as time goes by). Hence, the capacitor is the major factor limiting the lifetime of the inverter systems. The aim of this work is to reduce the dc link capacitor size, as it means reduction of the cost and the volume of the converter/inverter systems. The work consists of 8 chapters: Chapter one illustrate the historical overview for the ac/dc/ac fed induction motor drive systems. It describes the benefits of the integrated PWM converter/inverter fed induction motor drive. It classified the integrated PWM converter/inverter systems into two types independent and dependent systems. It demonstrates some ideas for the control algorithms of these types of integrated systems. Chapter two introduces the mathematical model for the PWM converter. It explains the space vector PWM (SVPWM) method for
Directory of Open Access Journals (Sweden)
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.
Three-Phase PWM Power Conversion--The Route to Ultra High Power Density and Efficiency
Institute of Scientific and Technical Information of China (English)
J W Kolar; J Minib(o)ck; T Nussbaumer
2005-01-01
A review of three-phase PWM converter topologies which do show a low complexity/high reliability and high efficiency and power density and are therefore of main interest for a future industrial application is presented.A three-switch/level Boost-type PWM rectifier (VIENNA Rectifier),a Buck+Boost-type PWM rectifier with wide output voltage range and the AC/AC Sparse Matrix Converter concept are discussed in detail and topics to be treated in the course of further research are identified. Finally,it is shown how the aspects being relevant for the realization of highly compact converter systems could be integrated into education in the field.
PWM Technique for Non-Isolated Three-Phase Buck-Boost PFC Converter
Morizane, Toshimitsu; Shimomori, Wataru; Taniguchi, Katsunori; Kimura, Noriyuki; Ogawa, Masanori
The buck-boost power factor corrected (PFC) converter has the wide range of the dc output voltage. A new non-isolated three-phase hard-switching and a soft-switching buck-boost PFC converter are proposed. Removing the three-phase transformer from the converters makes their size more compact and their costs lower. In addition, the new control method based on the PWM technique is proposed in this paper to achieve the high power factor. Complete soft-switching is also achieved under the discontinuous current mode (DCM) operation.
Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Zulkifilie Bin Ibrahim
2014-07-01
Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM. SPWM is the most simple modulation technique that can realize easily in analog circuit. However, it has some drawbacks such as higher total harmonic distortion (THD, lower effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.
A New PWM Modifying Technique for Reconstructing Three-phase Currents from DC Bus Current
Aoyagi, Shigehisa; Iwaji, Yoshitaka; Tobari, Kazuaki; Sakamoto, Kiyoshi
Vector control is used to drive a DC brushless motor and generally needs current information. DC bus current detection is often adopted as a low cost method for reconstructing three-phase currents. PWM modifying techniques increase the DC pulse duration, thereby enabling easy detection of the DC bus current. However, these techniques have two problems: reducing a noise frequency and making the reconstructed current waveforms distorted by current ripple. In the techniques, modification signals are added to the three-phase voltage commands; the sum of the signals over a single cycle is zero. The authors examined several PWM modifying techniques from the points of view of noise and current distortion performance. One of the techniques had a good noise performance, and the frequency component of the noise was the same as the carrier frequency (fc). However, the reconstructed current waveforms were distorted. The total harmonic distortion (THD) varied from 1.7% to 4.1%. Another technique had a very poor noise performance, and the frequency component on the noise was one-fourth of fc. The authors developed a new PWM modifying method called “Half Pulse Shift”, which achieves the optimum noise and current distortion performance. The frequency component of the new method was two-thirds of fc, and the current waveforms were not distorted; the THD in the simulations and experiments was 0.5%-1.4% and 3.4%-3.6%, respectively.
Microcontroller based PWM Inverter for Speed Control of a Three Phase Induction Motor
Directory of Open Access Journals (Sweden)
M. A. Latif
2013-04-01
Full Text Available Three phase induction motor has proven to be an extremely reliable electromechanical energy conversion device for over 100 years. The speed control of induction motor is a crying need for the real world industrial applications. However, there are so many options available for the precise speed control of induction motor except by changingthe frequency. Therefore to achieve the goal of speed control of induction motor, there is no alternative of inverters. With the availability of high speed power semiconductor devices, the three phase inverters play the key role for variable speed ac motor drives. In addition to the speed control, the inverter can also provide some unique features, like voltage control, torque control, power factor correction, auto breaking, built in protection system and so forth.In this paper, a three phases PWM inverter using MC3PHAC microcontroller with computer interface is proposed to run a squirrel case induction motor. Some results of the proposed inverter are presented.
Microcontroller based PWM controlled four switch three phase inverter fed induction motor drive
Directory of Open Access Journals (Sweden)
Mohanty Kant Nalin
2010-01-01
Full Text Available This paper presents PIC microcontroller based PWM inverter controlled four switch three phase inverter (FSTPI fed Induction Motor drive. The advantage of this inverter that uses of 4 switches instead of conventional 6 switches is lesser switching losses, lower electromagnetic interference (EMI, less complexity of control algorithms and reduced interface circuits. Simulation and experimental work are carried out and results presented to demonstrate the feasibility of the proposed approach. Simulation is carried out using MATLAB SIMULINK and in the experimental work a prototype model is built to verify the simulation results. PIC microcontroller (PIC 16F877A is used to generate the PWM pulses for FSTPI to drive the 0.5 hp 3-phase Induction Motor.
DEFF Research Database (Denmark)
Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede;
2016-01-01
This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative...... parameters to evaluate converter parameters for any application. The equations obtained were confirmed by simulation and experimental setup. Field of application has been discussed....
Directory of Open Access Journals (Sweden)
Ramakrishna Manohar Anaparthi
2014-12-01
Full Text Available This paper explains that how to develop and design, control of single phase to three phase drive system. The proposed topology of drive system consisting of two parallel connected rectifiers, inverter and induction motor, connected through inductor and capacitor, where used to produce balanced output to the motor drive. The main objective of this proposed method is to reduce the circulating currents and harmonic distortions at the converter input side, here the control strategy of drive system is PWM (pulse width modulations techniques control strategy, the proposed topology also provides fault compensation in the case of short circuit faults and failure of switches for uninterrupted Power supplies. We also develop and simulate the MATLAB models for proposed drive system, by using MATLAB/ Simulink the output results simulate and observed.
A PAC Based Current Feedforward Control for Three-Phase PWM Voltage-Type Converter
Institute of Scientific and Technical Information of China (English)
屈克庆; 陈国呈; 孙承波
2004-01-01
This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC). With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed. For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle. Also, the algorithm is derived and the system principle is introduced. Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.
Institute of Scientific and Technical Information of China (English)
彭一芯; 魏建勋; 黄辉先; 方鑫; 陆建龙
2015-01-01
For the problem that the system input parameters exists disturbances when the traditional sliding-mode varia-ble-structure control(SMVSC)is applied to the three-phase voltage source PWM rectifier,an online solution that sliding-mode variable-structure control base on improved PID neural network design was presented in this paper,taking three pa-rameters of PID as neurons of neural network in the hidden layer and considering that PID algorithm is of fast response,no static error and the online self-learning ability of neural network,the PID algorithm and neural network is combined to modi-fy the sliding approaching rate parameter in real-time,thus the time of system state into the sliding surface and jitter is re-duced.Through improving the selected value function,the algorithm cannot fall into local minimum and the global optimal solution is approached;also,the overall stability of the system is analyzed.Finally into simulation and experimental valida-tion research,show that the method possesses smaller shake and preferable dynamic response.%针对传统滑模变结构控制在三相电压型 PWM 整流器中应用时参数摄动所引起的抖动现象，提出一种改进 PID 神经网络的滑模变结构在线控制方法，将 PID 三个参数作为神经网络隐藏层的神经元，利用 PID 算法响应快、无静差的特点以及神经网络的在线自学习能力，实时对滑模趋近律参数进行修改，从而缩短系统状态进入滑模面的时间并减小抖动。对选取的价值函数进行改进，使算法不会陷入局部最优而逼近全局最优解，并对系统的全局稳定性进行分析。通过仿真和实验验证，结果表明该方法能使系统全局稳定，抖动有明显削弱且具有更好的动态响应。
Indian Academy of Sciences (India)
Manoj Kumar Modi; S Venugopal; G Narayanan
2013-06-01
The equivalence of triangle-comparison-based pulse width modulation (TCPWM) and space vector based PWM (SVPWM) during linear modulation is well-known. This paper analyses triangle-comparison based PWM techniques (TCPWM) such as sine-triangle PWM (SPWM) and common-mode voltage injection PWM during overmodulation from a space vector point of view. The average voltage vector produced by TCPWM during overmodulation is studied in the stationary (a–b) reference frame. This is compared and contrasted with the average voltage vector corresponding to the well-known standard two-zone algorithm for space vector modulated inverters. It is shown that the two-zone overmodulation algorithm itself can be derived from the variation of average voltage vector with TCPWM. The average voltage vector is further studied in a synchronously revolving (d-q) reference frame. The RMS value of low-order voltage ripple can be estimated, and can be used to compare harmonic distortion due to different PWM methods during overmodulation. The measured values of the total harmonic distortion (THD) in the line currents are presented at various fundamental frequencies. The relative values of measured current THD pertaining to different PWM methods tally with those of analytically evaluated RMS voltage ripple.
An Optimal PR Control Strategy with Load Current Observer for a Three-Phase Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Xiaobo Dou
2015-07-01
Full Text Available Inverter voltage control is an important task in the operation of a DC/AC microgrid system. To improve the inverter voltage control dynamics, traditional approaches attempt to measure and feedforward the load current, which, however, needs remote measurement with communications in a microgrid system with distributed loads. In this paper, a load current observer (LCO based control strategy, which does not need remote measurement, is proposed for sinusoidal signals tracking control of a three-phase inverter of the microgrid. With LCO, the load current is estimated precisely, acting as the feedforward of the dual-loop control, which can effectively enlarge the stability margin of the control system and improve the dynamic response to load disturbance. Furthermore, multiple PR regulators are applied in this strategy conducted in a stationary frame to suppress the transient fluctuations and the total harmonic distortion (THD of the output voltage and achieve faster transient performance compared with traditional dual-loop control in a rotating dq0 frame under instantaneous change of various types of load (i.e., balanced load, unbalanced load, and nonlinear load. The parameters of multiple PR regulators are analyzed and selected through the root locus method and the stability of the whole control system is evaluated and analyzed. Finally, the validity of the proposed approach is verified through simulations and a three-phase prototype test system with a TMS320F28335 DSP.
DEFF Research Database (Denmark)
Lar, Ionut Andrei; Radulescu, Mircea; Ritchie, Ewen
2012-01-01
A comparison between two current control methods of grid side inverter, PI current control and Robust Forward control is made. PI control is implemented in d-q synchronous frame while Forward is implemented in abc stationary frames.The report contains both simulations and experimental test wich w...
Step-by-Step Design Procedure for a Grid-Connected Three-Phase PWM Voltage Source Converter,
DEFF Research Database (Denmark)
Liserre, Marco; Blaabjerg, Frede; Aquila, Antonio Dell
2004-01-01
controllers. In this paper a step-by-step design procedure, taking into account all these elements, is proposed and validated through the tests on an experimental prototype. The reported results are particularly relevant to evaluate the influence on the grid current harmonic content of the grid sensor...
Passivity-Based Control by Series/Parallel Damping of Single-Phase PWM Voltage Source Converter
del Puerto Flores, Dunstano; Scherpen, Jacqueline; Liserre, Marco; de Vries, Martijn M. J.; Kransse, Marco J.; Monopoli, Vito Giuseppe
2014-01-01
This paper describes a detailed design procedure for passivity-based controllers developed using the Brayton-Moser (BM) framework. Several passivity-based feedback designs are presented for the voltage-source converter, specifically for the H-bridge converter, since nowadays it is one of the preferr
Institute of Scientific and Technical Information of China (English)
樊英杰; 张开如; 韩璐; 狄东照; 鲁金生
2015-01-01
The topology structure of three-phase voltage-source PWM rectifier( VSR) and the basic principle of voltage oriented control( VOC) were presented.In view of the shortage of the traditional space vector pulse width modulation ( SVPWM) algorithm applied in three-phase VSR, this paper puts forward an optimized SVPWM, by which the sector can be judged according to the rotating argument of voltage space vector, and the function time of basic voltage vector can be calculated based on the three-phase voltage difference computation.Compared with the former two methods, the coordinate transformation and trigonometric calculation are completely omitted and the algorithm steps are simpli-fied in the optimized SVPWM.The validity and practicability can be verified through the simulation of VOC system with MATLAB/SIMULINK, which provides the basis for the hardware design of the improved three-phase VSR.%介绍了三相电压型PWM整流器（VSR）的拓扑结构和电压定向控制（VOC）的基本原理。针对三相VSR传统中电压空间矢量（ SVPWM）算法的缺陷性，提出了一种优化SVPWM调制方法。该方法利用电压空间矢量旋转的幅角来判断扇区，并由相电压的电压差值计算基本电压矢量的作用时间，完全省略了坐标变换和三角函数计算，化简了SVPWM算法步骤。经过MATLAB／SIMULINK建立电压定向控制（ VOC）仿真模型，可以证明该优化SVPWM算法的正确性，为改进三相VSR的硬件设计提供了依据。
A Fuzzy-Logic-Based Controller for Three-Phase PWM Rectifier With Unity Power Factor Operation
Directory of Open Access Journals (Sweden)
A. Bouafia
2008-03-01
Full Text Available In this paper, direct power control (DPC of three-phase PWM rectifiers based on fuzzy logic controller is presented, without line voltage sensors. The control technique is built upon the ideas of the well known direct torque control (DTC for induction motors. The instantaneous active and reactive powers, directly controlled by selecting the optimum state of the converter, are used as the PWM control variables instead of the phase line currents being used. The proposed fuzzy logic controller presents the advantage to be based on linguistic description and does not require a mathematical model of the system. The controller ensures a good regulation of the output voltage, and guarantees the power factor close to one. The simulation results show that the designed fuzzy controller has a good dynamic behavior, a good rejection of impact load disturbance, and is very robust.
Chen, Lei; Tang, Yuejin; Shi, Jing; Li, Zhi; Ren, Li; Cheng, Shijie
2010-02-01
The integrated voltage compensation type active superconducting fault current limiter (SFCL) is composed of three air-core superconducting transformers and a three-phase four-wire PWM converter. In order to realize the current-limiting characteristics of the integrated active SFCL, it is needed to control the three-phase four-wire PWM converter flexibly and reasonably. Thereby, the control strategy for the converter is analyzed in this paper. In dq0 reference frame, the mathematical model of the converter is founded. The double-loop control strategy, consisting of voltage outer loop and current inner loop, is presented. Moreover, the voltage balance control for the split DC link capacitors is also considered. Using MATLAB, the simulation model of the integrated active SFCL is built. According to the simulation results, it is known that, the presented control strategy is feasible and valid, and the converter can work well under unsymmetrical and symmetrical fault conditions, and then the fault current can be limited quickly and effectively.
DUAL THREE-PHASE ADJUSTABLE SPEED DRIVE WITH SYNCHRONIZED SPACE-VECTOR MODULATION
Directory of Open Access Journals (Sweden)
Oleschuk V.I.
2008-04-01
Full Text Available Split-phase symmetrical motor drive on the base of two voltage source inverters, controlled by algorithms of synchronized pulse width modulation (PWM, has been investigated. Simulation results are presented for dual three-phase power conversion systems with continuous, discontinuous and combined versions of synchronized PWM.
Directory of Open Access Journals (Sweden)
Hong-yu Zhu
2013-01-01
Full Text Available Broken rotor bars fault detection in inverter-fed squirrel cage induction motors is still as difficult as the dynamics introduced by the control system or the dynamically changing excitation (stator frequency. This paper introduces a novel fault diagnosis techniques using motor current signature analysis (MCSA to solve the problems. Switching function concept and frequency modulation theory are firstly used to model fault current signal. The competency of the amplitude of the sideband components at frequencies (1±2sfs as indices for broken bars recognition is subsequently studied in the controlled motor via open-loop constant voltage/frequency control method. The proposed techniques are composed of five modules of anti-aliasing signal acquisition, optimal-slip-estimation based on torque-speed characteristic curve of squirrel cage motor with different load types, fault characteristic frequency determination, nonparametric spectrum estimation, and fault identification for achieving MCSA efficiently. Experimental and simulation results obtained on 3 kW three-phase squirrel-cage induction motors show that the model and the proposed techniques are effective and accurate.
High frequency three-phase PWM grid connected drive using silicon-carbide switches
DEFF Research Database (Denmark)
Kouchaki, Alireza; Pedersen, Jacob Lykke; Nymand, Morten
2016-01-01
and with this compensation. The controller is designed for a 5 kW SiC based three-phase rectifier (switching frequency 50 kHz) connected to a 7.5kW SiC based inverter (switching frequency 32 kHz). Experimental results are also carried out to validate the operation of the controller under different operating conditions...
在线自适应PWM死区消除方法%Online Adaptive Dead-Time Elimination Method for PWM Voltage Source Inverters
Institute of Scientific and Technical Information of China (English)
杨波; 吴建德; 李武华; 何湘宁
2011-01-01
A novel online adaptive dead-time elimination method is presented in this paper for PWM voltage source inverters,based on the analysis of dead-time effects and the principle of dead-time elimination.Tracking the load change on-line and determining dynamically the current direction,the zero current zone and the non zero current zone of the output inductor are precisely distinguished and the optimal width of the zero current zone is adaptively calculated.Furthermore,the dead-time effects are completely eliminated in the whole sinusoidal modulation cycle.In comparison with traditional dead-time compensation and elimination methods,the proposed method can significantly restrain the output distortion in the zero current zone and reduce the low-frequency harmonic contents and THD.The simulation and experimental results demonstrate the validity and practicability of the proposed method.%通过对死区效应原理和死区消除原则的分析,提出一种在线自适应的PWM死区消除方法。该方法通过在线跟踪负载变化,自适应地计算出最优的电感电流过零区域宽度,以精确实现电流过零区域和电流非过零区域中死区效应的分别消除,从而在整个正弦调制周期内达到最佳的死区消除效果。与传统的死区消除和补偿方法相比,该方法对电流过零处电压畸变的抑制效果尤为明显,能有效地降低输出电压低次谐波含量,使THD明显减小。仿真和实验结果证明了该死区消除方法的有效性和实用性。
Yamada, Hiroaki; Tanaka, Toshihiko; Funabiki, Shigeyuki
This paper proposes a new inrush current suppressor using a series-connected small-rated PWM converter for a transformer. The PWM converter is directly connected in series between the source and transformer without a matching transformer. The inrush phenomena of the matching transformer, thus, can be avoided. The control gain and required-ratings of the series-connected small-rated PWM converter is discussed in detail. The capacity of the dc capacitor of the PWM converter is also discussed considering the active power flows into the PWM converter. The PSCAD/EMTDC is used to verify the validity of the proposed inrush current suppressor. A prototype experimental model is constructed and tested. The experimental results demonstrate that the proposed suppressor can perfectly overcome the inrush phenomena of transformers.
Energy Technology Data Exchange (ETDEWEB)
Leon, Andres E.; Solsona, Jorge A.; Busada, Claudio; Chiacchiarini, Hector [Instituto de Investigaciones en Ingenieria Electrica (IIIE) UNS-CONICET, Universidad Nacional del Sur, Av. Alem 1253, Bahia Blanca 8000 (Argentina); Valla, Maria Ines [Laboratorio de Electronica Industrial, Control e Instrumentacion (LEICI) and CONICET, Facultad de Ingenieria, Universidad Nacional de La Plata, La Plata 1900 (Argentina)
2009-08-15
In this paper a new control strategy for voltage-source converters (VSC) is introduced. The proposed strategy consists of a nonlinear feedback controller based on feedback linearization plus a feedforward compensation of the estimated load current. In our proposal an energy function and the direct-axis current are considered as outputs, in order to avoid the internal dynamics. In this way, a full linearization is obtained via nonlinear transformation and feedback. An estimate of the load current is feedforwarded to improve the performance of the whole system and to diminish the capacitor size. This estimation allows to obtain a more rugged and cheaper implementation. The estimate is calculated by using a nonlinear reduced-order observer. The proposal is validated through different tests. These tests include performance in presence of switching frequency, measurement filters delays, parameters uncertainties and disturbances in the input voltage. (author)
DEFF Research Database (Denmark)
Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede
2015-01-01
This paper considered a six-phase (asymmetrical) induction motor, kept 30 phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs) and all four dc sources are deliberately kept isolated......) by nearest three vectors (NTVs) approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/ Simulink-PLECS software) of whole ac drive system by observing the dynamic behaviors in different designed condition. Set...
Directory of Open Access Journals (Sweden)
Sanjeevikumar Padmanaban
2015-09-01
Full Text Available This paper considered a six-phase (asymmetrical induction motor, kept 30° phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom based on synchronous field oriented control (FOC. A standard three-level space vector pulse width modulation (SVPWM by nearest three vectors (NTVs approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/Simulink-PLECS software of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development.
电压型PWM逆变器控制技术的改进%The Improvement of Control Technology for Voltage Source PWM Inverter
Institute of Scientific and Technical Information of China (English)
李雪龙; 周渊深; 李少鹏
2013-01-01
For the purpose of enhancing PWM inverter’s dynamic decoupling effects in current control loop, this paper apply IMC method to PWM inverter which is based on double (voltage and current) close-loop control. In addition, a kind of AC current regulator is designed, and its compensation signal as well as DC correction signal are together to determine the output of control, which reduces fluctuations at the DC side. In this paper, the waveforms via Simulink of the advanced scheme are presented, and the simulation results confirm the validity of the mentioned strategy.%基于电压型PWM逆变器电压电流双闭环控制框架，针对电流环的交叉耦合问题，采用内模解耦（IMC）方法以提高PWM逆变器动态过程中的解耦效果。除此以外，设计了交流电流调节器，其补偿信号与直流电流调节器的校正信号相加共同产生控制量的输出，以降低直流侧电压的波动性。给出了整体改进方案的Simulink仿真波形，结果证明了改进方案的可行性和有效性。
Design on Anti-disturbance for Three-phase PWM Rectifier%三相电压型PWM整流器抗扰动设计
Institute of Scientific and Technical Information of China (English)
郑征; 周文斌
2012-01-01
分析了三相电压型PWM整流器的基本原理并进行了建模.针对传统的双闭环控制下,直流母线电压受负载扰动和电网波动影响较大的问题,根据整流器功率平衡的原则,提出了电压外环采用前馈补偿(负载电流和电网电压)和输出电压反馈的控制方法,该方法有效地改善PWM整流器的抗扰动能力,仿真结果验证了控制策略的有效性和正确性.%The basic principle of the three-phase PWM rectifier was analyzed and the model was established. With the traditional double-loop control. The load disturbance and grid voltage fluctuations have a great influence on the DC bus voltage. According to the principle of power balance for rectifier, the outer control loop which is based on feed-forward compensation (load current and power voltage) and output voltage feedback control were proposed. This method effectively improves the anti-disturbance ability of PWM rectifier. Simulation results show the effectiveness and validity of control strategies.
Feedforward Synchronised PWM for Adjustable Speed AC Drives with Different Control Modes
DEFF Research Database (Denmark)
Oleschuk, Valentin; Blaabjerg, Frede; Jensen, Flemming Buus
2002-01-01
This paper presents a novel method of direct synchronised pulswidth modulation (PWM) for three-phase voltage source inverters, feeding induction motors with different control regimes. It is based on the universal algorithm with either simplified algebraic or accurate trigonometric control functions...
A novel three-phase-bridge cascaded PWM converter%一种新型的三相桥级联型PWM变换器
Institute of Scientific and Technical Information of China (English)
陆治国; 赵丽丽; 吴春军; 祝万平
2012-01-01
The traditional single-phase cascaded H-bridge converter (CHBC) can not be used for three-phase high-voltage applications directly, thus a novel topology of three-phase-bridge (3P-Bridge) cascaded PWM converter is proposed and its basic cell is a 3P-Bridge. Its construction idea is analyzed and the currents and power expressions are derived. The proposed topology in this paper can not only be operated as a rectifier but also an inverter. One-cycle control (OCC) and CPS-PWM are employed for their simulation research separately. Simulation results verify the feasibility of the proposed 3P-Bridge cascaded converter and show that the proposed topology can improve the voltage level, and comparing with the traditional single-phase CHBC, it can reduce the number of switches and DC capacitors (or separated DC sources), and the voltage ripple at DC side is smaller. So the proposed 3P-Bridge cascaded converter has better prospect in three-phase high-voltage applications.%传统的单相级联H桥变换器不易直接应用于三相高压场合,为此提出了三相桥级联型PWM变换器的拓扑结构,其子模块为电压源型三相桥式变换器.分析了该新型拓扑的构成思想,推导了二级和三级级联拓扑的电流和功率表达式,其可做整流器也可做逆变器,分别采用单周控制和载波相移控制对其进行仿真研究.仿真结果验证了该新型拓扑的可行性,表明其能够提升电压等级,与传统的单相级联H桥变换器构成的三相变换器相比,能够节省开关管和直流侧电容(独立电源)个数,且直流侧电压纹波较小,在三相高压场合具有较好的应用前景.
三相电压型PWM整流器的仿真与实验研究%Study of Three-phase PWM Voltage Rectifier's Simulation and Experiment
Institute of Scientific and Technical Information of China (English)
赵建勇; 王清灵; 芮秀凤; 刘军华
2011-01-01
The paper analyzed the three-phase PWM rectifier's basic principle, and built mathematical model under the three-phase static coordinate axis and rotating coordinate axis. It adopted the closed loop control technology of voltage and circuit, and the control technology of space voltage vector to make up the control system, and studied the influence of variation in load to the system and the principle of energy reversible in rectifier. Finally, it validated the system through the matlab/simulink, and built the experiment system based on TMS2812-DSP. Both the simulation and experiment verify the system has good dynamic and static performance, and nearly to be unit power factor.%分析了三相PWM整流器基本原理,建立了在三相静止坐标系以及两相旋转坐标系中的数学模型.采用电压电流双闭环控制以及空间电压矢量PWM技术构建了控制系统,探究了负载变化对系统的影响,以及整流器能量可逆的原理.最后通过Matlab/Simulink仿真进行了验证,并搭建了基于TMS2812-DSP的实验平台.仿真及实验结果均表明系统具有良好的动、静态性能,且功率因数接近为1.
Institute of Scientific and Technical Information of China (English)
钟庆; 黄凯; 王钢; 张尧
2014-01-01
不对称三相电压下，电压源型换流器(VSC)将产生低次谐波，给电网造成谐波污染。随着VSC在电力系统中的广泛应用，这类问题必须得到更多的关注，提出有效的解决方法。基于动态相量和序分量，推导出序分量动态相量，并对其特性进行了分析；将含开关函数描述的VSC时域模型转化为动态相量模型；定义交流电流和直流电压的各阶序分量动态相量为状态变量，建立了以状态空间描述的VSC序分量动态相量谐波分析模型，综合考虑了开关函数的详细动态特性和交直流侧谐波的相互作用，从而揭示了 VSC 产生谐波的机理，实现了 VSC 谐波的解析求解。在此基础上，提出负序补偿的不对称调制策略，以抑制低次谐波的产生。通过各种不对称情况下的仿真和计算，验证了所提出的谐波分析模型的正确性和谐波抑制策略的有效性。%A voltage source converter (VSC) will generate low-order harmonics under unbalanced three-phase voltage causing harmonic pollution to power grids.With the wide application of VSCs in power systems,the harmonic pollution must be eliminated and given more attention by finding effective solutions.Based on dynamic phasors and symmetrical components,the sequence dynamic phasor is deduced and its characteristics are analyzed.The time domain VSC model containing a description of switching function is transformed into a dynamic phasor model.By setting the sequence dynamic phasors of AC current and DC voltage as the state variables,a harmonic analysis model in the state space based on the sequence dynamic phasors of VSC is developed.The model considers both the dynamic performance of power electronic devices and the interaction between AC and DC sides thus revealing the mechanism of how VSC generates harmonics.Based on the model,the harmonics generated by VSC can be calculated analytically.A harmonic elimination strategy with an
Fuzzy Logic Controlled Solar Module for Driving Three- Phase Induction Motor
Afiqah Zainal, Nurul; Sooi Tat, Chan; Ajisman
2016-02-01
Renewable energy produced by solar module gives advantages for generated three- phase induction motor in remote area. But, solar module's ou tput is uncertain and complex. Fuzzy logic controller is one of controllers that can handle non-linear system and maximum power of solar module. Fuzzy logic controller used for Maximum Power Point Tracking (MPPT) technique to control Pulse-Width Modulation (PWM) for switching power electronics circuit. DC-DC boost converter used to boost up photovoltaic voltage to desired output and supply voltage source inverter which controlled by three-phase PWM generated by microcontroller. IGBT switched Voltage source inverter (VSI) produced alternating current (AC) voltage from direct current (DC) source to control speed of three-phase induction motor from boost converter output. Results showed that, the output power of solar module is optimized and controlled by using fuzzy logic controller. Besides that, the three-phase induction motor can be drive and control using VSI switching by the PWM signal generated by the fuzzy logic controller. This concluded that the non-linear system can be controlled and used in driving three-phase induction motor.
A Novel Simulation Research on Double Closed-loop of Three-phase PWM Rectifier%一种新型双闭环三相PWM整流器的仿真研究
Institute of Scientific and Technical Information of China (English)
雷美艳; 欧阳昌华; 朱俊杰
2011-01-01
采用一种基于输入输出电流解耦反馈的控制策略和PI调节方法，以三相整流器在d-q同步旋转坐标系中的模型为基础，建立电流内环和电压外环的PWM整流器简化数学模型，并且运用MATLABR2009a建立系统仿真模型，保证输出电压的稳定性。%The basic principle of three-phase PWM rectifier is introduced in this paper. A control strategies of decoupling of input and output current based on feedback and methods for regulation of PI is used, and the simplified mathematical model of the PWM rectifier of the current inner loop and outer voltage is established, which is based on the model of the d-q synchronous rotating coordinate system in three-phase rectifier, and a simulation model of the PWM rectifier, which can achieve the stability of the output voltage, is established by the MATLAB R2009a.
一种新型的双闭环三相PWM整流器仿真分析%Novel Simulation Research on Double Closed-Loop of Three-Phase PWM Rectifier
Institute of Scientific and Technical Information of China (English)
雷美艳; 欧阳昌华; 朱俊杰
2011-01-01
The basic principle of three-phase PWM rectifier is introduced.The control strategies of decoupling of input and output current based on feedback and the methods of PI regulation are used,and the simplified mathematical model of the PWM rectifier of the current inner loop and outer voltage is established,which is based on the model of the d-q synchronous rotating coordinate system in three-phase rectifier.A simulation model of the PWM rectifier,which can achieve the stability of the output voltage,is established by the MATLAB R2009a.The simulation results verify that the proposed method is effective and practical.%介绍了三相PWM整流的基本原理,并以三相整流器在d-q同步旋转坐标系中的模型为基础,采用基于输入输出电流解耦反馈控制策略和PI调节方法,建立了电流内环和电压外环的PWM整流器简化数学模型.运用MatlabR2009a建立了系统仿真模型,实现了输出电压的稳定性,仿真结果验证了该方法的有效性和实用性.
Morimoto, Keiki; Doi, Toshimitsu; Manabe, Haruhiko; Ahmed, Tarek; Hiraki, Eiji; Lee, Hyun-Woo; Nakaoka, Mutsuo
This paper presents a new circuit topology of full-bridge soft-switching PWM inverter linked DC-DC power converter composed of conventional full-bridge high frequency PWM inverter with high frequency transformer and an active quasi-resonant snubber consisting of an additional power switching device in series with DC busline and a lossless capacitor in parallel with DC busline. Under this proposed high frequency soft-switching PWM inverter linked DC-DC converter, four power switches in the full-bridge arms and DC busline series switch can achieve ZVS at turn-off commutation. By developing the advanced soft-switching PWM high frequency inverter type DC-DC converter, although the conduction power loss of DC busline series power switch increases a little, the total turn-off switching loss of full-bridge high frequency inverter power modules can be sufficiently lowered more and more in the higher frequency range of 60kHz. As a result, when the switching frequency of high frequency inverter power stage using IGBT power modules is designed so as to be more than about 10kHz, the more the switching frequency of inverter increases, the more this high frequency soft-switching DC-DC converter has remarkable advantage as for the power conversion efficiency as compared with the conventional hard-switching PWM inverter DC-DC converter. Its practical effectiveness of high power density and high performance is actually proved for TIG arc welding equipment in industry.
DEFF Research Database (Denmark)
Blaabjerg, Frede; Aquila, A. Dell; Liserre, Marco;
2004-01-01
A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...... of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters...
Directory of Open Access Journals (Sweden)
P. Gopal,
2015-11-01
Full Text Available The main objective of this concept is to examine the operation of fundamental buck-based three-phase singlestage ac–dc full-bridge converters. In this concept, the operation of this fundamental converter is explained and analyzed, and a procedure for the design of its key components is derived and demonstrated with an example and general concluding remarks comparing Buck-Based and Boost Based three Phase single-stage AC to DC full Bridge converters are made.
Institute of Scientific and Technical Information of China (English)
屈克庆; 陈国呈; 孙承波
2005-01-01
A novel software implementation for current polarity detection and current compensation is presented. For a three-phase zero-voltage soft-switching (ZVS) PWM converter based on phase and amplitude control (PAC), when saw-tooth carriers with alternate positive and negative slopes are adopted, the positive or negative slopes are chosen according to the phase current polarity. Since polarity reversal causes current distortion, current at the instant of reversal should be compensated for. Based on the characteristic of unity power factor converter in rectification and regeneration modes, a software implementation for current polarity detection is proposed.Distortion of current zero-crossing caused by using saw-tooth carriers with alternate positive and negative slopes is analyzed, and the relevant compensation method is proposed. Experimental study with a 1.5 kW device shows that phase current has a small harmonic content and power factor is high both in rectification and regeneration modes.
五相电压源逆变器的空间矢量脉宽调制方法研究%Research of Space Vector PWM Techniques for Five-phase Voltage Source Inverter
Institute of Scientific and Technical Information of China (English)
高宏伟; 杨贵杰; 刘剑
2014-01-01
To improve the DC bus voltage utilization of five-phase voltage source inverter (VSI) and reduce the harmonic component of output phase voltages, a space vector pulse width modulation (SVPWM) algorithm of five-phase VSI based on adjacent four voltage vectors was proposed. According to the value of modulation index, the modulation range could be divided into sine modulation region and non-sine modulation region. In sine modulation region, the output phase voltages are standard sine waves without any harmonic component through allocating the action time of space vector appropriately. In non-sine modulation region, through optimizing the voltage vector in harmonic subspace, not only the DC bus voltage utilization is improved effectively, but also the harmonic component of output phase voltages is minimized. Simulation and experimental results verify the correctness and feasibility of the proposed algorithm.%为提高五相电压源逆变器(voltage source inverter，VSI)的直流母线电压利用率，减少输出相电压中所含的谐波分量，提出一种改进的基于最近四矢量的五相 VSI 空间矢量脉宽调制算法。根据调制系数的不同，将整个调制范围分为正弦调制区和非正弦调制区。在正弦调制区，通过合理分配空间矢量的作用时间，使得输出相电压为标准正弦波形，不含有任何谐波成分；在非正弦调制区，通过对谐波子空间内的电压矢量进行优化控制，在进一步提高直流母线电压利用率的同时，保证输出相电压中所含谐波分量更少，使逆变器工作在最优状态。仿真和实验结果验证了所提算法的正确性和可行性。
Directory of Open Access Journals (Sweden)
Mechouma Rabiaa
2014-01-01
Full Text Available In recent years, power demand of industrial applications has increased significantly reaching some megawatts. The use of multilevel converters for applications of medium and high powers is proposed as a solution to drawback semiconductor technology. A multilevel converter not only achieves high power ratings, but also enables the use of renewable energy sources. Renewable energy sources such as photovoltaic can be easily interfaced to a multilevel converter system for a high power application. This paper presents the simulation study in Matlab/Simulink of a grid connected photovoltaic three phase Neutral Point Clamped (NPC inverter with DC/DC boost converter for constant and variable solar radiation.
Institute of Scientific and Technical Information of China (English)
高洋; 尹忠东
2011-01-01
For Electric Vehicle (EV) chargers, the modified strategy of Direct Power Control based on voltage source PWM rectifier is proposed. First, the topological structure of PWM rectifier is introduced. Then the basic principle and control characteristic of traditional Direct Power Control (DPC) system with six interval divisions is analyzed, based on which a control method with twelve interval divisions is proposed to improve the control characteristics. Then this new method is deduced in detail, and the switch table which is defined by this method is proposed. Finally, the modified Direct Power Control method is validated by PSCAD, and simulation on the switch table is implemented by using of QuartusII9.0, which shows that each data can reach its predefined index.%针对电动汽车充电器,提出了基于电压型PwM整流器的改进的直接功率控制策略.首先,介绍了PWM整流器的拓扑结构;然后分析了传统的六区间直接功率控制系统的基本原理和控制特性;为了改善控制特性,在传统六区间的控制方法的基础上,提出了十二区间的控制方法,并对该方法进行了详细推导和阐述,给出了在该方法定义下的开关表;最后用PSCAD对改进的直接功率控制方法进行了可行性验证,用QuartusII9.0对开关表进行了仿真,发现各项数据都可以达到预期指标.
Space Vector Pulse Width Modulation Scheme for a Seven-Phase Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Mohd. Arif Khan
2011-09-01
Full Text Available This paper analyses a simple space vector PWM (SVPWM scheme for a seven-phase voltage source inverter. At first the conventional method of producing sinusoidal output voltage by utilizing six active and a zero space vectors are used to synthesis the input reference and then new PWM scheme called time equivalent space vector PWM is presented. A comparison of the proposed scheme with the conventional scheme is presented based on various performance indices. Extensive Simulation results are provided to validate the findings
Paul, R. N.; Arya, L. D.; Verma, H. K.
2012-09-01
In three-phase squirrel-cage ac traction motor, temperature-rise calculation during variable-voltage and variable-frequency starting is of vital importance and has to be predicted and critically examined. Under voltage source inverter supply with PWM, the generation of harmonics by inverter supply reduces the output during starting due to higher harmonic losses, thereby reducing the starting tractive effort in kN on locomotive wheel. Stator and rotor temperature-rises during starting have been determined for average acceleration torque in segmental zone (calculated from variable acceleration) which have been presented in the paper with both copper and aluminium alloy rotor bars.
Grid control strategy of wind turbine based on double voltage source rectifier%基于双VSR的风电机组并网控制策略
Institute of Scientific and Technical Information of China (English)
葛俊旭; 李鑫; 童水光; 吴德忠; 田志刚; 王鹏
2011-01-01
针对兆瓦级永磁同步发电机组并网的控制要求,基于三相电压型脉宽调制(PWM)整流器的数学模型,重点研究了直接电流控制双闭环级联结构的三相电压型PWM整流器和基于SVPWM的三相电压型PWM整流器的控制系统设计,提出基于双电压型PWM整流器(VSR)的风力发电机组的并网控制策略,并建立该控制策略的等效电路模型.通过对该并网控制策略等效电路模型的仿真分析,验证了PWM整流器的升压整流特性;同时,该等效电路输出的三相交流相电流总谐波畸变率仅为1.64%,电流波形正弦度良好.仿真结果验证了该并网控制策略的可行性.%For grid control of permanent magneticm synchronous generator, according to the mathematcalmodel of three-phase voltage source rectifier, this work emphatically studied the controller design of three-phase voltage source rectifier(VSR), which has double closed-loop and cascade structure based on the direct current control, and voltage source rectifier based on space vector pulse width modulation. The grid control strategy based on double voltage source rectifier for wind turbine generators was and proposed the corresponding equivalent circuit model was established. The simulation to this grid control strategy's equivalent circuit proved the rising voltage speciality of pulse width modulation (PWM). The current's total harmonic distortion of the grid side output's three-phase AC interphase was only 1.64％, and its waveform was batter. The new control strategy was proved feasible by Simulink simulation.
Directory of Open Access Journals (Sweden)
Gabriele Grandi
2016-05-01
Full Text Available This paper gives the complete analysis of the output current ripple in three-phase voltage source inverters considering the different discontinuous pulse-width modulation (DPWM strategies. In particular, peak-to-peak current ripple amplitude is analytically evaluated over the fundamental period and compared among the most used DPWMs, including positive and negative clamped (DPWM+ and DPWM−, and the four possible combinations between them, usually named as DPWM0, DPWM1, DPWM2, and DPWM3. The maximum and the average values of peak-to-peak current ripple are estimated, and a simple method to correlate the ripple envelope with the ripple rms is proposed and verified. Furthermore, all the results obtained by DPWMs are compared to the centered pulse-width modulation (CPWM, equivalent to the space vector modulation to identify the optimal pulse-width modulation (PWM strategy as a function of the modulation index, taking into account the different average switching frequency. In this way, the PWM technique providing for the minimum output current ripple is identified over the whole modulation range. The analytical developments and the main results are experimentally verified by current ripple measurements with a three-phase PWM inverter prototype supplying an induction motor load.
Institute of Scientific and Technical Information of China (English)
文生平; 瞿金平
2001-01-01
A high－performance and high－precision PWM motion controller SA866 is presented here．Its digitizing control manner and flexible operation mode make it easy to controlthe motors with the simple controlcircuits．The frequency－varied speed－regulated inverter based on SA866 is also discussed．%文章介绍了一种智能型、高精度PWM运动控制器SA866，其控制实行全数字化，加上灵活的工作方式使电机易于控制，硬件电路简洁、可靠。最后给出了变频器控制的实例。
用于三相PWM并网逆变器的改进型幅相控制方法%The improved PAC method for a three-phase PWM grid-connected inverter
Institute of Scientific and Technical Information of China (English)
李杰; 马祎炜; 陈国呈; 王得利; 俞俊杰
2008-01-01
In this paper, a vector regulating principle of the phase and amplitude control (PAC) method for three-phase grid-connected inverters is presented. To solve the problem of heavy inrush current and slow dynamic response when system starts up, the starting voltage prediction control and the current feed-forward control are proposed and used, which improve the dynamic performance of the system in the PAC. The experimental results carried out on a three-phase grid-connected inverter proved the validity of the proposed method.
Institute of Scientific and Technical Information of China (English)
屈克庆; 陈国呈; 孙承波
2004-01-01
This paper presents a novel current feedforward control strategy for a three-phase pulse-width modulation (PWM) DC voltage-type converter based on phase and amplitude control (PAC).With right-angle triangle relation of phasors and principle of conservation of energy, a phasor adjustment method and the relevant low-frequency mathematical model of the system are analyzed in detail, both in rectification and regeneration modes for the converter, are discussed.For improving the traditional PAC dynamic performance, variable load current is detected indirectly by the change of the DC voltage, which is fed to the control system as an additional control variable to generate modulation index and phase angle.Also, the algorithm is derived and the system principle is introduced.Experimental results from a 3 kw laboratory device are included to demonstrate the effectiveness of the proposed control strategy.
Institute of Scientific and Technical Information of China (English)
郑玮仪; 曾志勇; 赵荣祥
2016-01-01
对故障后并网型三相脉宽调制(pulse width modulation, PWM)变换器系统建模、矢量调制技术和系统控制策略3个方面进行详细的研究.分析容错后变换器工作原理,建立容错后电力变换器三相静止模型.该模型揭示了故障后电容中性点电压波动的固有原因.利用伏秒平衡原理,推导基于三相静止系下矢量调制方法,该方法无需复杂的三角函数运算,且具有统一的表达公式.利用电流纹波有效值对容错后矢量调制算法进行评估,以便选择电流性能良好的调制算法.为防止中性点电压偏移对系统造成的影响,提出一种基于修正故障相调制波的中性点电压偏移控制方法,保证故障后并网变换器稳定安全运行.实验结果证明,所提方法提高电流品质,实现了故障后并网变换器稳定安全运行.
Institute of Scientific and Technical Information of China (English)
唐雄民; 朱燕飞
2011-01-01
A predictive direct power control strategy for three-phase pulse width modulation rectifier was presented. Based on instantaneous active and reactive power theory, the rectifier s active and reactive power variations were predicted in the next sampling period and control vector of rectifier was directly calculated. With control vector of rectifier,space vector modulation was used to generate the required switch pulse of con verter in a constant switching frequency. The impact of sampling delay and online calculation delay on the accu racy of active and reactive power was analyzed,and the compensation method was achieved. Simulation results validate the control strategy and compensation method.%提出了一种基于功率预测模型的三相PWM整流器控制策略.控制策略利用瞬时功率理论预测下一个固定周期内电路的有功和无功变化,直接求取整流器交流侧的电压矢量,并采用空间矢量调制方法来保证整流器工作频率的恒定.还对由于采样、实时计算等原因引起的延时对电路有功和无功的影响进行探讨,并给出了补偿方法.仿真结果验证了控制策略和补偿方法的有效性.
Directory of Open Access Journals (Sweden)
S. Elangovan
2014-07-01
Full Text Available The main aim of this study is to control a multivariable coupled system by choosing sliding mode switching function. A Sliding mode control approach is developed to control a three phase three wire voltage source inverter operating as a shunt active power filter. Hence, no need to divide the system model developed in the synchronous ‘dq’ reference frame into two separate loops. Furthermore, the proposed control strategy allows a better stability and robustness over a wide range of operation. When sine PWM is used for generation of pulses for the switches, a variable switching nature is exhibited. The pulses for the active filter are fed by a Space Vector Modulation in order to have a constant switching of converter switches. But, the conventional space vector modulation, if implemented practically, needs a complicated algorithm which uses the trigonometric functions such as arctan, Sine and Cosine functions which in turn needs look up tables to store the pre-calculated trigonometric values. In this study, a very simplified algorithm is proposed for generating Space vector modulated pulse for all six switches without the use of look up tables and only by sensing the voltages and currents of the voltage source inverter acting as shunt active filter. The simulation using PSIM and MATLAB software verifies the results very well.
DEFF Research Database (Denmark)
Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth;
2015-01-01
As the increasing of power electronics based systems, not only the component-based analysis but also a systematic interaction analysis with each other systems are being important. Especially studies about the stability and the harmonics interaction are critical in order to establish the required ...
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
This letter presents a multi-frequency proportional-resonant (MFPR) current controller developed for PWM voltage source converter (VSC) under the unbalanced supply voltage conditions. The delta operator is used in place of the shift operator for the implementation of MFPR by using a low-cost fixed-point DSP. The experimental results with an alternative control strategy validated the feasibility of the proposed MFPR current controller for the PWM VSC during voltage unbalance.
Directory of Open Access Journals (Sweden)
Valentin Oleschuk
2011-01-01
Full Text Available Novel method of space-vector-based pulse-width modulation (PWM has been disseminated for synchronous control of four inverters feeding six-phase drive on the base of asymmetrical induction motor which has two sets of windings spatially shifted by 30 electrical degrees. Basic schemes of synchronized PWM, applied for control of four separate voltage-source inverters, allow both continuous phase voltages synchronization in the system and required power sharing between DC sources. Detailed MATLAB-based simulations show a behavior of six-phase system with continuous and discontinuous versions of synchronized PWM.
Analysis of Input and Output Ripples of PWM AC Choppers
Directory of Open Access Journals (Sweden)
Pekik Argo Dahono
2008-11-01
Full Text Available This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.
A novel design methodology for low pass filter stage of a voltage source inverter
Indian Academy of Sciences (India)
ANIRBAN DE
2016-05-01
A low pass filter, an invariable constituent of a PWM based voltage source inverter, poses several challenges in its design. With a higher rating of the inverter, the volume as well as the cost of the components increases. With time, the filter design has evolved from the simpler first order filter to higher orders, the most popular being the third order LCL filters. Though the attenuation of high frequency components, offered by the higher order filters, has resulted in improved efficiency, the inherent instability of the higher order filter systemsrequires complex controls for proper functioning. Keeping this in mind, the paper describes the design methodology of a second order LC filter system based on certain performance indices that reflect the ratings of the components.
Dynamic Performance of a Back-to-Back HVDC Station Based on Voltage Source Converters
Khatir, Mohamed; Zidi, Sid-Ahmed; Hadjeri, Samir; Fellah, Mohammed-Karim
2010-01-01
The recent developments in semiconductors and control equipment have made the voltage source converter based high voltage direct current (VSC-HVDC) feasible. This new DC transmission is known as "HVDC Light or "HVDC Plus by leading vendors. Due to the use of VSC technology and pulse width modulation (PWM) the VSC-HVDC has a number of potential advantages as compared with classic HVDC. In this paper, the scenario of back-to-back VSC-HVDC link connecting two adjacent asynchronous AC networks is studied. Control strategy is implemented and its dynamic performances during disturbances are investigated in MATLAB/Simulink program. The simulation results have shown good performance of the proposed system under balanced and unbalanced fault conditions.
Improved direct power control of a grid-connected voltage source converter during network unbalance
Institute of Scientific and Technical Information of China (English)
Peng ZHOU; Wei ZHANG; Yi-kang HE; Rong ZENG
2010-01-01
This paper deals with an improved direct power control(DPC)strategy for the pulse width modulation(PWM)voltage source converter(VSC)under unbalanced grid voltage conditions.In order to provide enhanced control performance for the VSC,the resonant controllers tuned at the double grid frequency are applied in the DPC design to eliminate the power pulsations and dc link voltage ripples produced by the transient unbalanced grid faults.In this way,the output power and dc link voltage of the VSC can be directly regulated without positive and negative sequential decomposition.As a result,and as has been verified by experiment,the proposed method can provide fast dynamic response with easy implementation.
Directory of Open Access Journals (Sweden)
N. Belhaouchet
2008-03-01
Full Text Available Hysteresis current control is one of the simplest techniques used to control the magnitude and phase angle of motor current for motor drives systems. However, this technique presents several disadvantages such as operation at variable switching frequency which can reveal problems of filtering, interference between the phases in the case of the three-phase systems with insulated neutral connection or delta connection, and irregularity of the modulation pulses which especially causes an acoustic noise on the level of the machine for the high power drive. In this paper, a new technique is proposed for a variable-hysteresis-band controller based on dead beat control applied to three phase voltage source PWM inverters feeding AC motors. Its main aim is firstly ensure a constant switching frequency and secondly the synchronization of modulation pulses using the phase-locked-loop with loop gain compensation in order to ensure a better stability. The behavior of the proposed technique is verified by simulation.
Control to Three-phase Inverter by Sliding Mode
Directory of Open Access Journals (Sweden)
Mouhamadou Thiam
2014-03-01
Full Text Available In this study, it is treated the modeling and the ordering of a three-phase inverter. The studied system is a load supplied with a three-phase inverter by means of a transformer. The ordering of the inverter is with PWM (pulse-width modulation/pulse-width Modulation and its regulation is made by the sliding method. This method is presented in this document with its various laws. The simulation of the unit is made and the results presented.
Relationships between Harmonic Characteristics and Different Types of Voltage Source
Directory of Open Access Journals (Sweden)
Yusniati Yusniati
2012-06-01
Full Text Available This paper discusses about harmonic characteristics due to different types of voltage sources. Usually, the voltage source is sinusoidal. But in actual condition the load that receive voltage sources through the elements where the output voltage of element as input to the load is not pure sinusoidal, for example voltage source at (PCC between transformer and linear load and nonlinear load. This research has been done with Schhafner Power Quality Analyzer and PM300 Power Quality Analyzer, was focused to all harmonic characteristics as power, voltage, current, power factor (p.f., Harmonic Distortion, and harmonic energy losses cost. The load is Induction Motor with Adjustable Speed Drive (ASD because the Induction Motor with Adjustable Speed Drive (ASD is one of electronic device causes harmonics. The voltage sources in this research are sine wave, square wave and harmonic order combinations of 3rd, 5th and 7th which can create from Schhafner Power Quality Analyzer.
Optimal condition of memristance enhancement circuit using external voltage source
Directory of Open Access Journals (Sweden)
Hiroya Tanaka
2014-05-01
Full Text Available Memristor provides nonlinear response in the current-voltage characteristic and the memristance is modulated using an external voltage source. We point out by solving nonlinear equations that an optimal condition of the external voltage source exists for maximizing the memristance in such modulation scheme. We introduce a linear function to describe the nonlinear time response and derive an important design guideline; a constant ratio of the frequency to the amplitude of the external voltage source maximizes the memristance. The analysis completely accounts for the memristance behavior.
A Study on Power Quality Improvement in PWM Controlled AC Voltage Controller
Directory of Open Access Journals (Sweden)
Ahmet ALTINTAŞ
2009-04-01
Full Text Available A lot of topologies of pulse-width modulated (PWM-AC controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC controllers using thyristors and triacs. The PWM-AC controller has sinusoidal current waveforms, smaller THD values, better power factor, faster dynamics, and smaller input/output filter. This article presents a novel control technique for application to PWM-AC controllers with ability of generating fewer harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined; and smaller THD values are obtained. Thus, the harmonic pollution in the power system will be reduced; and consequently, the power quality will be increased. For this purpose, computer simulations are performed in order to investigate the proposed controller performance. The obtained results are compared with the conventional PWM-AC controller.
Dynamics of voltage source converter in a grid connected solar photovoltaic system
DEFF Research Database (Denmark)
Haribabu, Divyanagalakshmi; Vangari, Adithya; Sakamuri, Jayachandra N.
2015-01-01
This paper emphasises the modelling and control of a voltage source converter (VSC) for three phase grid connected PV system. The transfer functions for inner current control and outer DC link voltage control for VSC are derived. The controllers for VSC are designed based on PI and K factor contr...... conditions. The effectiveness of the proposed controller is illustrated by evaluating the response of PV system for power system voltage sag and swell conditions as well as grid faults.......This paper emphasises the modelling and control of a voltage source converter (VSC) for three phase grid connected PV system. The transfer functions for inner current control and outer DC link voltage control for VSC are derived. The controllers for VSC are designed based on PI and K factor control...... methods and the performance of VSC using both the methods are presented with the simulations performed using PSCAD/EMTDC. The design of LC filter to meet the specified THD requirement for grid connected VSC is presented and the corresponding harmonic analysis is performed for different solar radiation...
DEFF Research Database (Denmark)
Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick
2016-01-01
This paper presents a novel carrier based multilevel modulation for modified dual three-phase open-winding inverter applicable for low-voltage/high-current applications. A standard three-phase voltage source inverter (VSI) is connected across the open-winding of both ends of the motor. Each VSI...
Institute of Scientific and Technical Information of China (English)
庞科旺; 袁文华; 刘丽丽
2008-01-01
把PWM整流技术引入到内馈斩波串级调速系统中,这样不仅可以提高串级调速系统的功率因数和减少交流侧的谐波含量,还可以有效地防止系统的逆变颠覆故障.建立了应用于串级调速系统的电压型PWM整流器的静态解耦模型,以此为基础进行了系统设计,并通过仿真验证了该方案的可行性.
A COMPREHENSIVE ANALYSIS OF SPACE VECTOR PWM TECHNIQUE BASED ON PLACEMENT OF ZERO-SPACE VECTOR
Directory of Open Access Journals (Sweden)
G.SAMBASIVA RAO,
2011-04-01
Full Text Available In this paper, the effect of placement of zero-space vector for the implementation of space vector based Pulse Width Modulation techniques for 3-phase Voltage Source Inverter is presented. Several pulse width modulation (PWM control strategies have been proposed for 3-phase voltage source inverter (VSI in the past. It is known that space vector modulation (SVM offers a degree of freedom in its implementation with regard to the placement of the zero-space vector. Apart from constructing a consistent theoretical framework, simulation results with conventional continuous SVM and various discontinuous SVM techniques are presented and all the cases are compared in this paper.
A Review of Passive Power Filters for Three-Phase Grid-Connected Voltage-Source Converters
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei; Liserre, Marco;
2016-01-01
with the utility grid are reviewed, and evaluated in terms of damping capability, stored energy in the passive components and power loss in the damping circuit. Additionally, the influences of different switching frequencies of power converters on the passive filter design are also discussed in the range of 1-15 k...
Three-phase electric drive with modified electronic smoothing inductor
DEFF Research Database (Denmark)
Singh, Yash Veer; Rasmussen, Peter Omand; Andersen, Torben Ole
2010-01-01
This paper presents a three-phase electric drive with a modified electronic smoothing inductor (MESI) having reduced size of passive components. The classical electronic smoothing inductor (ESI) is able to control a diode bridge output current and also reduce not only mains current harmonics...... but also output voltage ripple. ESI performs the function of an inductor that has controlled variable impedance. MESI requires active switches with lower ratings than ESI and has the same performance. In MESI, an active voltage source realized by a low-voltage switch-mode converter stage is inserted...
PWM Converter Power Density Barriers
Kolar, Johann W.; Drofenik, Uwe; Biela, Juergen; Heldwein, Marcelo; Ertl, Hans; Friedli, Thomas; Round, Simon
Power density of power electronic converters has roughly doubled every 10 years since 1970. Behind this trajectory is the continuous advancement of power semiconductor devices, which has increased the converter switching frequencies by a factor of 10 every decade. However, today's cooling concepts and passive components are major barriers for a continuation of this trend. To identify such technological barriers, this paper investigates the volume of the cooling system and passive components as a function of the switching frequency for power electronic converters and determines the switching frequency that minimizes the total volume. A power density limit of 28kW/dm3 at 300kHz is calculated for an isolated DC-DC converter, 44kW/dm3 at 820kHz for a three-phase unity power factor PWM rectifier, and 26kW/dm3 at 21kHz for a sparse matrix converter. For single-phase AC-DC conversion a general limit of 35kW/dm3 results from the DC link capacitor. These power density limits highlight the need to broaden the scope of power electronics research to include cooling systems, high frequency electromagnetics, interconnection and packaging technology, and multi-domain modelling and simulation to ensure further advancement along the power density trajectory.
Nongrounded Common-Mode Equivalent Circuit for Brushless DC Motor Driven by PWM Inverter
Maetani, Tatsuo; Isomura, Yoshinori; Watanabe, Akihiko; Iimori, Kenichi; Morimoto, Shigeo
This paper describes nongrounded common-mode equivalent circuit for a motor driven by a voltage-source PWM inverter. When the capacitance of the rotor was small, the phenomenon that polarity of the common mode voltage and shaft voltage reversed was observed. In order to model this phenomenon, the bridge type equivalent circuit is proposed. It is verified with the calculation and experiment that shaft voltage values and polarity are accurately calculated with the proposed equivalent circuit.
Diode-Assisted Buck-Boost Voltage-Source Inverters
DEFF Research Database (Denmark)
Gao, Feng; Loh, Poh Chiang; Teodorescu, Remus;
2009-01-01
This paper proposes a number of diode-assisted buck-boost voltage-source inverters with a unique X-shaped diode-capacitor network inserted between the inverter circuitry and dc source for producing a voltage gain that is comparatively higher than those of other buck-boost conversion techniques...
Energy Technology Data Exchange (ETDEWEB)
Gheraia, H.; Berkouk, E.M. [ENP, Alger (Algeria). Lab. de Commande des Processus; Manesse, G. [CNAM-Paris (France). Lab. d' Electricite Industrielle
2001-08-01
In this paper, we study a new kind of continuous-alternating converters: a seven-level neutral point clamping (NPC) voltage source inverter (VSI). We propose this inverter for applications in high voltage and high power fields. In the first part, we develop the knowledge and the control models of this inverter using the connections functions of the semi-conductors. After that, we present two pulse width modulation (PWM) algorithms to control this converter using its control model. We propose these algorithms for digital implementation. This multilevel inverter is associated to the induction machine. The performances obtained are full of promise to use it in the high voltage and high power fields of electrical traction. (orig.)
Institute of Scientific and Technical Information of China (English)
Jia-bing HU; Wei ZHANG; Hong-sheng WANG; Yi-kang HE; Lie XU
2009-01-01
This paper proposes a current control scheme for a grid-connected pulse width modulator (PWM) voltage source converter (GC-VSC) under imbalanced and distorted supply voltage conditions. The control scheme is implemented in the positive synchronously rotating reference frame and composed of a single proportional integral (PI) regulator and multi-frequency resonant controllers tuned at the frequencies of 2ω and 6ω, respectively. The experimental results, with the target of eliminating the active power oscillations and current harmonics on a prototype GC-VSC system, validate the feasibility of the proposed current control scheme during supply voltage imbalance and distortion.
DEFF Research Database (Denmark)
Federico, de Bosio; de Sousa Ribeiro, Luiz Antonio; Freijedo Fernandez, Francisco Daniel
2017-01-01
and Smith predictor design, respectively, are obtained. Subsequently, the voltage regulator is also designed for a wide bandwidth, which permits the inclusion of resonant filters for the steady-state mitigation of odd harmonics at nonlinear unbalance load terminals. Discrete-time domain implementation......The decoupling of the capacitor voltage and inductor current has been shown to improve significantly the dynamic performance of voltage source inverters in standalone applications. However, the computation and PWM delays still limit the achievable bandwidth. In this paper a discrete-time domain...
Power Loss Calculation and Thermal Modelling for a Three Phase Inverter Drive System
Directory of Open Access Journals (Sweden)
Z. Zhou
2005-12-01
Full Text Available Power losses calculation and thermal modelling for a three-phase inverter power system is presented in this paper. Aiming a long real time thermal simulation, an accurate average power losses calculation based on PWM reconstruction technique is proposed. For carrying out the thermal simulation, a compact thermal model for a three-phase inverter power module is built. The thermal interference of adjacent heat sources is analysed using 3D thermal simulation. The proposed model can provide accurate power losses with a large simulation time-step and suitable for a long real time thermal simulation for a three phase inverter drive system for hybrid vehicle applications.
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Maheshwari, Ram Krishan; Bede, Lorand;
2015-01-01
for the maximum value of the flux linkage are derived for each of these PWM schemes. In addition, the effect of the proposed PWM scheme on the line current ripple and the switching losses is also analyzed and compared. To verify the analysis, experimental results are presented, which prove the effectiveness......Parallel voltage-source converters (VSCs) require an inductive filter to suppress the circulating current. The size of this filter can be minimized by reducing either the maximum value of the flux linkage or the core losses. This paper presents a modified discontinuous pulsewidth modulation (DPWM......) scheme to reduce the maximum value of the flux linkage and the core losses in the circulating current filter. In the proposed PWM scheme, the dwell time of an active vector is divided within a half-carrier cycle to ensure simultaneous occurrence of the same zero vectors in both VSCs. A function to decide...
Rowihal, Said Soliman
Both voltage-source and current-source inverters are widely used for supplying three-phase power to induction motor drives, each having their advantages and disadvantages. For high power drives and applications requiring accurate speed and tracking coordination, the synchronous motors are the optimum choice. For constant speed applications of synchronous motor drives, current-source inverters tend to be favored as the motor can usually be operated in the overexcited leading power factor region, thus providing the inverter with sufficient electro-motive force to allow natural commutation. Generally speaking low speed operation of synchronous motors is not satisfactory from naturally commutated current-source inverters. To provide a dynamic range of speed and frequency would require expensive control circuitry and complicates the performance of the drive. The advantage of the voltage-source inverter for the wide range of speed and frequency control herein envisaged is that forced commutation is employed throughout the range and the commutating circuits have been well developed and established. On balance, voltage-source inverters represent a viable compromise for variable-speed three -phase synchronous motor drives including start-up. To investigate the transient response of the voltage -source fed-synchronous motor drives, a digital computer program is developed. The program is based on two models --machine model and inverter model. The machine is represented by a detailed two-axis model which includes the effects due to saliency, damper windings, and machine resistances. The inverter model represents a forced-commutated voltage-source inverter assuming ideal switching devices (thyristors and diodes). To cope with the wide variations of power factor during start-up, a thyristor with a reverse connected parallel diode are integrated as a bidirectional switch. The digital program provides the machine variables of interest (phase currents, field current, damper winding
DEFF Research Database (Denmark)
Mathe, Laszlo; Lungeanu, Florin; Rasmussen, Peter Omand;
2010-01-01
This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on the measurements, it is shown that the spread effect of the discrete components from the motor current spectra is very effective independent of the modulation...... index. The flat motor current spectrum generates an acoustical noise close to the white noise, which may improve the acoustical performance of the drive. The new carrier wave is easy to implement digitally, without employing any external circuits. The modulation method can be used in open, as well...
A Phase Current Reconstruction Approach for Three-Phase Permanent-Magnet Synchronous Motor Drive
Directory of Open Access Journals (Sweden)
Hao Yan
2016-10-01
Full Text Available Three-phase permanent-magnet synchronous motors (PMSMs are widely used in renewable energy applications such as wind power generation, tidal energy and electric vehicles owing to their merits such as high efficiency, high precision and high reliability. To reduce the cost and volume of the drive system, techniques of reconstructing three-phase current using a single current sensor have been reported for three-phase alternating current (AC control system using the power converts. In existing studies, the reconstruction precision is largely influenced by reconstructing dead zones on the Space Vector Pulse Width Modulation (SVPWM plane, which requires other algorithms to compensate either by modifying PWM modulation or by phase-shifting of the PWM signal. In this paper, a novel extended phase current reconstruction approach for PMSM drive is proposed. Six novel installation positions are obtained by analyzing the sampling results of the current paths between each two power switches. By arranging the single current sensor at these positions, the single current sensor is sampled during zero voltage vectors (ZVV without modifying the PWM signals. This proposed method can reconstruct the three-phase currents without any complex algorithms and is available in the sector boundary region and low modulation region. Finally, this method is validated by experiments.
Design of New Single-phase Multilevel Voltage Source Inverter
Directory of Open Access Journals (Sweden)
Rasoul Shalchi Alishah
2014-07-01
Full Text Available Multilevel inverters with more number of levels can produce high quality voltage waveforms. In this paper, a new single-phase structure for multilevel voltage source inverter is proposed which can generate a large number of levels with reduced number of IGBTs, gate driver circuits and diodes. Three algorithms for determination of dc voltage sources’ magnitudes are presented which provide odd and even levels at the output voltage waveform. A comparison is presented between proposed multilevel inverter and conventional cascade topology. The proposed topology is analyzed by the experimental and simulation results.
Energy Technology Data Exchange (ETDEWEB)
Marcelino, M.A.; Silva, G.B.S.; Grandinetti, F.J. [Universidade Estadual Paulista (UNESP), Guaratingueta, SP (Brazil). Fac. de Engenharia; Universidade de Taubate (UNITAU), SP (Brazil)], Emails: abud@feg.unesp.br, gabonini@yahoo.com.br, grandinetti@unitau.br
2009-07-01
This paper presents a technique for speed control three-phase induction motor using the pulse width modulation (PWM), in open loop while maintaining the tension for constant frequency. The technique is adapted from a thesis entitled 'Control of the three-phase induction motor, using discrete PWM generation, optimized and synchronized', where studies are presented aimed at their application in home appliances, to eliminate mechanical parts, replaced by low cost electronic control, thus having a significant reduction in power consumption. Initially the experiment was done with the Intel 80C31 micro controller. In this paper, the PWM modulation is implemented using a PIC micro controller, and the speed control kept a low profile, based on tables, synchronized with transitions and reduced generation of harmonics in the network. Confirmations were made using the same process of building tables, but takes advantage of the program of a RISC device.
Three-phase Photovoltaic Systems
DEFF Research Database (Denmark)
Kerekes, Tamas; Sera, Dezso; Máthé, Lászlo
2015-01-01
the grid through a three-phase power electronic converter are now well on the way to becoming a major player in the power system in many countries. Therefore, this article gives an overview of photovoltaic systems with a focus on three-phase applications, presenting these both from a hardware point of view......Photovoltaic technology has experienced unprecedented growth in the last two decades, transforming from mainly off-grid niche generation to a major renewable energy technology, reaching approximately 180 GW of capacity worldwide at the end of 2014. Large photovoltaic power plants interfacing......, detailing the different photovoltaic inverter structures and topologies as well as discussing the different control layers within a grid-connected photovoltaic plant. Modulation schemes for various photovoltaic inverter topologies, grid synchronization, current control, active and reactive power control...
DESIGN THREE PHASE OVERCURRENT RELAYS
Directory of Open Access Journals (Sweden)
Mohammed Y Suliman,
2013-05-01
Full Text Available A new design of three phase overcurrent relay described in this paper. The performance of the new design shows the ability to obtain any shape of characteristic with high accuracy and distinguish between transient and steady state fault. This design used more precise and flexible model Sachdev linear model for get any characteristic, also fast measurement theory to measure load current for less than half cycle and good hardware system design controlled by Pentium version 4 processor.
Electrical machine PWM loss evaluation basics
Energy Technology Data Exchange (ETDEWEB)
Ruderman, A. [The School of Engineering, Bar-Ilan Univ., Ramat-Gan (Israel); Welch, R. Jr. [IEEE, Welch Enterprise, Oakdale (United States)
2005-07-01
Modern power converters utilize pulse-width modulation (PWM) voltage control. Output voltage high frequency harmonics induce additional electrical machine loss. As there is no accepted PWM loss theory, PWM loss is usually accounted for by machine power de-rating. In-depth understanding of PWM loss mechanisms is important for predicting losses and improving energy efficiency of electrical machines. In this paper we suggest a new time domain PWM loss approach. It assumes that PWM eddy current iron loss dominates over PWM copper and hysteresis iron losses and comprises theoretical normalized PWM loss evaluation and experimental characterization. Once maximal PWM loss is measured, it can be scaled for an arbitrary operating point using simple formula. Theoretical results are shown to be in a good agreement with a published experimental data. (orig.)
Three-phase multilevel inverter configuration for open-winding high power application
DEFF Research Database (Denmark)
Sanjeevikumar, Padmanaban; Blaabjerg, Frede; Wheeler, Patrick William
2015-01-01
This paper work exploits a new dual open-winding three-phase multilevel inverter configuration suitable for high power medium-voltage applications. Modular structure comprised of standard three-phase voltage source inverter (VSI) along with one additional bi-directional semiconductor device (MOSFET....../IGBT) per phase and two capacitors with neutral point. Hence, introduces the additional voltage levels in each phase of the VSI. Further, this paper developed a modified single carrier five-level modulation (MSCFM) scheme in such way to overcome the complexity of standard space vector modulations, ready...
New Space Vector Selection Scheme for VSI Supplied Dual Three-Phase Induction Machine
Directory of Open Access Journals (Sweden)
MILICEVIC, D.
2013-02-01
Full Text Available This paper presents a novel space vector selection scheme applicable for the control of dual three-phase induction motor drives supplied from a six-phase voltage source inverter (VSI. The vector selection method is based on the vector space decomposition technique (VSD. Unique vector selection pattern simplifies problems related to complicated implementation of standard VSD in commercially available digital signals processors (DSP. The proposed vector selection scheme is verified through a theoretical analysis, computer simulations and practical experimental results conducted on a dual three-phase test rig prototype with control algorithm implemented in Texas Instrument?s TMS320F2808 DSP.
Three-phase Resonant DC-link Converter
DEFF Research Database (Denmark)
Munk-Nielsen, Stig
no additional power electric components is eliminating the high voltage peaks associated with the resonant circuit. The resonant link voltage peaks are limited below 2.1 times the DC link voltages. A new principle eliminating former resonant converter stability problems are proposed, implemented and tested......The purpose of the project is to develop a three-phase resonant converter suitable for standard speed drives. The motivation for working with resonant converters is found in the problem of the standard converter type used today. In standard converter type Pulse Width Modulated-Voltage Source....... The high speed of the switches cannot be fully utilizied. By using a parallel resonant converter the switching happens at low or zero voltage which reduses switch losses. The dv/dt is controlled by the resonant circuit, and it is therefore reduced significantly. The perspective using a resonant converter...
Generalized SVPWM Algorithm for Two Legged Three Phase Multilevel Inverter
Directory of Open Access Journals (Sweden)
Devisree Sasi
2013-07-01
Full Text Available This paper establishes the inherent fractal structure in the space vector representation of two legged three phase multilevel inverters. The established fractal structure is utilized to propose a generalized algorithm for space vector PWM generation for two legged multilevel inverters. The voltage space vectors of higher level inverters can be generated from the voltage space vectors of equivalent 2-level inverter. The proposed algorithm can be easily extended to n-level inverters without any computational complexity and it doesn’t use any look up table for sector identification. The paper explains the proposed method for 5-level inverter and simulation results are presented for 2-level, 3-level and 5-level configurations in MATLAB/SIMULINK.
IGBT Fuses for Protection Against Explosion in Voltage Source Converters
DEFF Research Database (Denmark)
Blaabjerg, Frede; Iov, Florin; Rasmussen, H.
2004-01-01
The consequences of electrical faults can be severe; not only to the equipment, but also in the worse case, to people if safety principles are not observed. Every year new applications based on DC-link Voltage Source Converters are added and the demand for protection of power electronics increases...... regarding the high-power IGBT modules. Due to the fact that the power level increases more energy is stored in the DC-link and even with an active protection, a high-power IGBT still has a risk of case rupture (explode) when a circuit failure condition occurs. A possible solution is a protection...... of the converter with standard High Speed Fuses or High Speed IGBT fuses. It is discussed that protection can be achieved by introduction of IGBT fuse located in the DC-link. Experiments show that explosion can be avoided by use of High Speed Fuse protection and the added inductance of standard High Speed...
Review of multilevel voltage source inverter topologies and control schemes
Energy Technology Data Exchange (ETDEWEB)
Colak, Ilhami [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey); Kabalci, Ersan, E-mail: kabalci@nevsehir.edu.t [Department of Technical Programs, Vocational Collage of Haci Bektas, Nevsehir University, Hacibektas, Nevsehir 50800 (Turkey); Bayindir, Ramazan [Department of Electrical Education, Faculty of Technical Education, Gazi University, Besevler, Ankara 06500 (Turkey)
2011-02-15
In this study, the most common multilevel inverter topologies and control schemes have been reviewed. Multilevel inverter topologies (MLIs) are increasingly being used in medium and high power applications due to their many advantages such as low power dissipation on power switches, low harmonic contents and low electromagnetic interference (EMI) outputs. The selected switching technique to control the inverter will also have an effective role on harmonic elimination while generating the ideal output voltage. Intensive studies have been performed on carrier-based, sinusoidal, space vector and sigma delta PWM methods in open loop control of inverters. The selection of topology and control techniques may vary according to power demands of inverter. This paper and review results constitute a useful basis for matching of inverter topology and the best control scheme according to various application areas.
Mitigation of Lower Order Harmonics with Filtered Svpwm In Multiphase Voltage Source Inverters
Directory of Open Access Journals (Sweden)
K. Uday Kiran
2014-08-01
Full Text Available Multi-phase machines and drives is a topic of growing relevance in recent years, and it presents many challenging issues that still need further research. This is the case of multi-phase space vector pulse width modulation (SVPWM, which shows not only more space vectors than the standard three-phase case, but also new subspaces where the space vectors are mapped. In the digital implementation, multiphase reference voltages are sampled and fed into the digital modulator to produce gating signals at a constant clock rate f. This means a finite pulse-width resolution because the gating state transition can only occur at some specific time instants depending on frequency. This results in a deviation of produced phase voltages from the desired phase voltages, i.e., increasing harmonic distortion especially for a small modulation index signal. In the present paper a filtered space-vector pulse-width modulation (SVPWM considering finite pulse-width resolution is proposed to produce a switching sequence with reduced baseband harmonics for multiphase voltage source inverters (VSI. This is achieved by incorporating a pseudo feedback loop regarding weighted voltage difference between desired and produced phase voltages.
OPTIMAL PWM BASED ON REAL—TIME SOLUTION WITH NEURAL NETWORK
Institute of Scientific and Technical Information of China (English)
ShenZhongting; YanYangguang
2002-01-01
A novel concept of neural network based control in pulse-width modulation(PWM)voltage source inverters is presented.On the one hand,the optimal switching an-gles are obtained in real time by the neural network based controller；on the other hand,the output voltage is ad-justed to fit the expected value by neural network when input voltage or loads change.The structure of neural network is simple and easy to be realized by DSP hard-ware system.No large memory used for the existing opti-mal PWM schemes is required in the system.Theoreticalanlysis of the proposed so-called sparse neural network is provided,and the stability of the system is proved.Un-der the control of neural network the error of output volt-age descends sharply,and the system outputs ac voltage with high precision.
DEFF Research Database (Denmark)
Kouchaki, Alireza; Niroumand, Farideh Javidi; Haase, Frerk;
2015-01-01
circuit is used to provide the inductor current harmonic spectrum. Therefore, using the harmonic spectrum, the low and high frequency copper losses are calculated. The high frequency minor B-H loops in one switching cycle are also analyzed. Then, the loss map provided by the measurement setup is used...
Modeling and Simulation of DSP Controlled SV PWM Three Phase VSI
Saadoun, A.; Yousfi, A.; Amirat, Y.
The present research is concerned with the development of two space vector pulse width modulated VSI models using the software package Matlab. The theoretical principles underlying the space vector modulation technique are presented but have been limited to the few relations needed for the model implementation. The first model, the formulation of which is based on the concept of switching function associated with the semiconductor power switches, is a switched mode inverter while the second model, the sine mode inverter, is formulated in terms of the duty times cycles of the pole switches is a nearly perfect sine wave space vector controlled generator. By comparison to the switched mode inverter, the sine mode inverter exhibits a larger bandwidth to frequency demand. The reliability of the sine mode model has been checked against the experimental results available in the literature provided by Analog Device Corporation.
A novel PWM scheme to eliminate the diode freewheeling In the Inactive phase in BLDC motor
Institute of Scientific and Technical Information of China (English)
WEI Kun; HU Chang-sheng; ZHANG Zhong-chao
2006-01-01
The brushless DC motor (BLDCM) with trapezoidal electromotive force (back-EMF) waveform is used widely.In principle,when the motor runs in the 120°conduction mode,two of the three phases are active while the other phase is inactive at all times.However,a ripple current occurs in the inactive phase due to the diode freewheeling during the non-commutation period in the traditional pulse width modulation (PWM) methods,which aggravates the torque ripples.A new PWM method is proposed in this paper to eliminate the diode freewheeling during the non-commutation period in the inactive phase.As a result,the torque ripple is suppressed using the proposed method.The simulation and experimental results are demonstrated to verify the validity of the proposed PWM method.
Investigation of Power Factor on Harmonic Effect due to Types of Voltage Source
Directory of Open Access Journals (Sweden)
C.B. Risnidar
2011-01-01
Full Text Available This paper discussed about power factor on harmonic effect due to types of voltage source. Usually, the voltage source is sinusoidal. But in actual condition the load that has voltage sources through the elements where the output voltage of element as input to load is not pure sinusoidal, for example at Power of Common Coupling (PCC between transformer and linear load and nonlinear load. The research has been done with Schhafner Power Quality Analyzer and was focused to power factor (p.f., Total Harmonic Distortion (THD, and harmonic energy losses cost from measurement where load is Induction motor and Adjustable Speed Drive (ASD. As voltage source in this research are sine wave, square wave and combinations of 3rd, 5th and 7th harmonic order like harmonic 313, and harmonic 357.
Ahmed, Waheed; Usman Ali, Syed M.
2013-12-01
We have performed comparative studies of Space Vector Pulse Width Modulation (SVPWM) and Sinusoidal Pulse Width Modulation (SPWM) techniques utilizing MATLAB tools. During these investigations, we carried out intensive simulations, comprehensively analyzed the obtained results and compared the harmonic density, power factor (PF), & switching losses of SVPWM and SPWM. It has been observed during investigations that if the switching frequency is high then losses due to harmonics are negligible, thus based on obtained results we suggested that the SVPWM technique is a more reliable solution. Because SVPWM utilizes DC bus voltage more efficiently, generates less Total Harmonic Distortion (THD) and has higher output quality it provides flexible control of output voltage and output frequency for Variable Speed Drive (VSD).
Chen, Juan
2008-01-01
This report is the result of a Master Thesis work done at Seaward Electronics Inc. in Beijing, China from June to December in 2007. The main goal for this thesis is to verify and improve the performance of Honey-PWM DC-DC converter, which has been fabricated by a standard 0.6um CMOS processes. The project was started with studying of Buck converter structure. After the understanding of the converter structure, the project goes in to the analyses phase for each sub-cells, including the theory,...
Investigation of Harmonic Characteristics in Printer due to Different Types of Voltage Source
Directory of Open Access Journals (Sweden)
C. Risnidar
2012-01-01
Full Text Available This paper discusses about harmonic characteristics due to different types of voltage sources. Usually, the voltage source is sinusoidal. But in actual condition the load that receives voltage sources through the elements where the output voltage of element as input to the load is not pure sinusoidal, for example voltage source at Power of Common Coupling (PCC between transformer and linear load and nonlinear load. This research has been done with Schhafner Power Quality Analyzer and PM300 Power Quality Analyzer, was focused to all harmonic characteristics as power, voltage, current, power factor (p.f., Harmonic Distortion, and harmonic energy losses cost. The load is printer because the printer is one of electronic device causes harmonics. The voltage sources in this research are sine wave, triangle wave and harmonic order combinations of 3rd, 5th and 9th. Why this research discuses voltage source for Harmonic order 3rd, 5th and 9th and don not combination of 3rd, 5th and 7th, because the combination 3rd, 5th and 9th is more complicated then combination of 3rd, 5th and 7th.
Selection of Carrier Waveforms for PWM Inverter
Institute of Scientific and Technical Information of China (English)
陈国呈; 屈克庆; 许春雨; 孙承波
2003-01-01
In this paper the influence of different carrier waveforms upon the output characteristics of PWM inverter is described in detail. When a triangular carrier waveform is used in hard-switching PWM inverters, harmonics exist in the neighborhood of the output frequency of the inverter output voltage and current due to the dead time. The triangular carrier waveform used in soft-switching PWM inverter will cause difficulties in controlling resonance-trigger time, higher loss in the resonant circuit, and less utilization of the DC bus voltage. If a sawtooth carrier is used in hard-switching PWM inverter, there will be severe distortion in the current waveform. When sawtooth carriers with alternate positive and negative slopes are used in soft-switching PWM inverters, the resonancetrigger time is easy to control, and distortion in the output voltage and current caused by the dead time will not appear.
Directory of Open Access Journals (Sweden)
Rasoul Shalchi Alishah
2015-06-01
Full Text Available In recent, several numbers of multilevel inverter structures have been introduced that the numbers of circuit devices have been reduced. This paper introduces a new structure for multilevel inverter which can be used in high-power applications. The proposed topology is based on cascaded connection of basic units. This topology consists of minimum number of circuit components such as IGBT, gate driver circuit and antiparallel diode. For proposed topology, two methods are presented for determination of dc voltage sources values. Multi-carrier PWM method for 25-level proposed topology is used. Verification of the analytical results is done using MATLAB simulation.
Scalar Controlled Boost PWM Rectifier for Micro Wind Energy Systems
Directory of Open Access Journals (Sweden)
J. Chelladurai
2015-05-01
Full Text Available Uses of Permanent Magnet Synchronous Generators (PMSG are increasing in variable speed micro-Wind Energy Conversion Systems (WECS. In stand-alone or grid-connected Micro-WECS, extraction of maximum power is vital. To extract maximum power output and to obtain a constant DC bus voltage from variable magnitude and variable frequency voltage output of PMSG and generally a two stage scheme namely i conventional diode bridge rectifier and ii DC-DC Boost/Buck/Buck-Boost converters are used. In this study, a single stage Scalar Controlled PWM (SCPWM Boost Rectifier is proposed in order to minimize the current harmonics and to improve the power factor on source side. The modeling and simulation of PMSG based wind generator and SCPWM Boost rectifier was developed in MATLAB. The harmonic content in the input current waveform of the proposed SCPWM rectifier is compared with the conventional three-phase bridge rectifier. The Simulation results show the effectiveness of the PWM Boost rectifier in terms of effective utilization of source, improved efficiency and harmonic mitigation for PMSG based Wind Generator. Simulation results demonstrate the effectiveness of the proposed system in reducing the current and voltage THD on source side.
DEFF Research Database (Denmark)
Federico, de Bosio; Pastorelli, Michele; Antonio DeSouza Ribeiro, Luiz
2016-01-01
State feedback coupling between the capacitor voltage and inductor current deteriorates notably the performance during transients of voltage and current regulators in stand-alone systems based on voltage source inverters. A decoupling technique is proposed, considering the limitations introduced ...... by system delays. Laboratory experiments were executed in compliance with the normative for Uninterruptible Power Supply systems to prove the developed analysis.......State feedback coupling between the capacitor voltage and inductor current deteriorates notably the performance during transients of voltage and current regulators in stand-alone systems based on voltage source inverters. A decoupling technique is proposed, considering the limitations introduced...
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
Active damping and harmonic compensation are two common challenges faced by LCL-filtered voltage source converters. To manage them holistically, this paper begins by proposing a virtual RC damper in parallel with the passive filter capacitor. The virtual damper is actively inserted by feeding back...... in the laboratory with results obtained for demonstrating stability and harmonic compensation....
Investigation of Grid-connected Voltage Source Converter Performance under Unbalanced Faults
DEFF Research Database (Denmark)
Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde
2016-01-01
Renewable energy sources (RES) and HVDC links are typically interfaced with the grid by power converters, whose performance during grid faults is significantly different from that of traditional synchronous generators. This paper investigates the performance of grid-connected voltage source...
Influence of current limitation on voltage stability with voltage sourced converter HVDC
DEFF Research Database (Denmark)
Zeni, Lorenzo; Jóhannsson, Hjörtur; Hansen, Anca Daniela;
2013-01-01
A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters’ behaviour when reaching their rated current. The detrimental effect of entering the current...
Assessment of the impact that individual voltage source has on a generator’s stability
DEFF Research Database (Denmark)
Dmitrova, Evgeniya; Jóhannsson, Hjörtur; Nielsen, Arne Hejde
2012-01-01
This paper presents an approach for splitting equivalent Thevenin voltage into components induced by each voltage source in the reduced grid. Thevenin equivalent representation of the system is sometimes used for stability assessment of a given generator, where the Thevenin voltage is one of the ...... countermeasures aimed on instability prevention. Suggested approach for Eth decomposition is applied to the IEEE 30 bus test system....
The overview of damping methods for three-phase grid-tied inverter with LLCL-filter
DEFF Research Database (Denmark)
Huang, Min; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
damping, passive damping or even without damping if it is designed conservative. In this paper, an overview of damping methods for three-phase voltage-source grid-tied with LLCL-filter is given. This paper also analyzes damping principle of each method including passive damping and active damping......Compared with LCL filter, an LLCL-filter is characterized with smaller size and lower cost for grid-connected inverters. But this high order filter may also have resonant problem which will affect the system stability. Many methods can be used to alleviate the resonant problem including active...
High performance predictive current control of a three phase VSI: An experimental assessment
Indian Academy of Sciences (India)
Vikas Kumar; Prerna Gaur; A P Mittal
2014-12-01
Delay has a significant role to play in the implementation of the predictive current control scheme as large amount of calculations are involved. Compensating delay in the predictive current controller design can lead to an improved load current total harmonic distortion (THD) and also an increased switching frequency. Minimization of switching frequency while maintaining the lower value of load current THD requires multiple objective optimization which is achieved by optimizing a single objective function, constructed using weighting factors as a linear combination of individual objective function. The effect of weighting factor on the switching frequency minimization and the current tracking error with delay compensation for the two level voltage source inverter (VSI) are investigated in this paper. The outcomes of the predictive current control using an optimized weighting factor which is calculated using branch and bound algorithm with the delay compensation are compared with the PWM based current control scheme. The experimental tests are conducted on a 2.2 kW VSI to verify the simulation observations.
Design of Load Current Feedforward PWM Rectifier Based on STM32%基于STM32的负载电流前馈PWM整流器设计
Institute of Scientific and Technical Information of China (English)
黄金飞; 唐小琦; 宋宝; 程建军
2015-01-01
For three-phase voltage source PWM rectifier under the traditional double closed-loop PI control strategy, the output dc voltage fluctuates with load current and the adjustment lasts long. By analyzing the disturbance response of the system, a load current feedforward control strategy is put forward. The disturb-ance current is measured directly as the faster current loop input instruction. This method overcomes the de-lay of the cascading closed-loop adjustment, so as to improve the dynamic response performance. An im-proved rectifier device was designed based on STM32F103Z. Three high speed ADs, an advanced timer TIM1, an integrated USB module and other on chip resources were used. The experimental results show that the load current feed-forward PWM rectifier based on STM32 has dramatically improved anti-load disturb-ance performance.%针对三相电压型PWM整流器在传统双闭环PI控制策略下，输出直流电压会随负载电流波动并且调整时间长这一问题，在分析系统扰动响应的基础上，提出了负载电流前馈控制方法。通过直接测量扰动电流，并将其作为电流环输入指令，以克服级联闭环调节带来的延迟，使得整流器输出电流紧紧跟随负载电流，进而提高输出电压的动态响应。为验证控制策略的可行性和有效性，利用STM32 F103 Z芯片的3个12位AD、高级定时器TIM1、集成USB模块等片上资源搭建了改进的整流装置，实验结果表明，基于STM32的负载电流前馈PWM整流器抗负载扰动能力得到了明显改善。
Institute of Scientific and Technical Information of China (English)
刘勇; 黎建勋
2015-01-01
Electric propulsion system has been used widely in fishing vessels the technology improving. Electric propulsion system with three-phase PWM rectifier, has already been mature in the technology. But for part of fishing vessel with single-phase AC power supply system, the research and application for electric propulsion system is less. This paper introduces the basic principlesof single-phase voltage source PWM rectifier, analyze the predictive current control methods. The dynamic response and the static precision of four-quadrant converter with predictive current control methodsare much better. In this paper, through computer simulations to verify the feasibility of predictive current control methods and validity of the main circuit parameter selection. Then, through experimental platform debugging which withTMS320LF2407 DSP chip as the core, the result is very well coincident with the simulated result. It shows that this method has good dynamic and static performance, can meet the need of four-quadrant converter design requirementscompletely. It is an ideal control method.%随着电力推进系统在我国渔业船舶上的不断推广应用，在系统中采用三相交流PWM整流器在技术上已经比较成熟。本文从单相电压型PWM整流器的基本原理出发，对预测电流控制方法进行了分析，认为该方法进一步改善了四象限变流器的动态响应特征，提高了稳态控制精度。通过计算机仿真试验，验证了预测电流算法的可行性以及主电路参数选择的正确性，并在仿真的基础上，以TMS320LF2407 DSP控制芯片为核心，实现了预测电流控制算法在三相PWM整流器小功率实验平台上的软件调试。试验结果与仿真有很好的一致性，表明该方法具有较好的动态、静态性能，完全能够达到四象限变流器的设计要求，是一种比较理想的控制方法。
Fuzzy Logic Based Speed Control System for ThreePhase Induction Motor
Directory of Open Access Journals (Sweden)
Marwan A. Badran
2013-05-01
Full Text Available Three-phase induction motors have been used in a wide range of industry applications. Using modern technology, the speed of induction motor can be easily controlled by variable frequency drives (VFDs. These drives use high speed power transistors with various switching techniques, mainly PWM schemes. For several decades, conventional control systems were applied to electric drives to control the speed of induction motor. Although conventional controllers showed good results, but they still need tuning to obtain optimum results. The recent proposed control systems use fuzzy logic controller (FLC to enhance the performance of induction motor drives. In this paper, a fuzzy logic based speed control system is presented. The proposed controller has been designed with MATLAB/SIMULINK software, and it was tested for various operating conditions including load disturbance and sudden change of reference speed. The results showed better performance of the proposed controller compared with the conventional PI controller.
High-frequency, three-phase current controller implementation in an FPGA
Energy Technology Data Exchange (ETDEWEB)
Hartmann, M.; Round, S. D.; Kolar, J. W.
2008-07-01
Three phase rectifiers with switching frequencies of 500 kHz or more require high speed current controllers. At such high switching frequencies analog controllers as well as high speed digital signal processing (DSP) systems have limited performance. In this paper, two high speed current controller implementations using two different field-programmable gate arrays (FPGA) - one for switching frequencies up to 1 MHz and one for switching frequencies beyond 1 MHz - are presented to overcome this performance limitation. Starting with the digital system design all the blocks of the signal chain, containing analog-to-digital (A/D) interface, digital controller implementation using HW-multipliers and implementation of a novel high speed, high resolution pulse width modulation (PWM) are discussed and compared. Final measurements verify the performance of the controllers. (author)
Self oscillating PWM modulators, a topological comparison
DEFF Research Database (Denmark)
Poulsen, Søren; Andersen, Michael Andreas E.
2004-01-01
High precision control of the output voltage or current of a switch mode converter with fast response is required for a number of applications. Dependent on the type of application, the desired precision and transient response can be difficult, if not impossible, to achieve with standard PWM...... control caused by limitations in dynamic capabilities which often limits fast tracking of a reference signal, or fast settling during load steps due to too small achievable control loop bandwidth. Achievable open loop bandwidth for standard voltage and current mode PWM modulators is typical in the fs/10...... to fs which makes this type of modulators an excellent choice for a wide range of applications. Self oscillating PWM modulators can be made in a number of ways, either as voltage or current mode modulators, and the self oscillating behavior can be achieved either by using hysteresis control...
Institute of Scientific and Technical Information of China (English)
窦亚力; 乔海强; 钱帆; 李龙光; 李子久
2016-01-01
In order to meet the inverter of trigger requirements applied to the power electronic , this paper primarily presents a novel method of using OMAPL 138 and FPGA to implement multi-channel PWM pulse generator with three-level PWM inverters .The pulse generator receives the PWM pattern parameters and setting parameters from OMA-PL138 processor through a built-in parallel interface , and produces the three-phase PWM driven signals by FPGA without the OMAPL138 intervention .The hardware architecture , basic principles , implementation method of the pulse generator described in this paper is verified by simulation and experiment .Three phase PWM generators have the fea-tures of simplifying circuit-design, improving reliability of system and guaranteeing concurrent triggering of power de-vices.%为了满足一种新能源发电领域的电力电子变换装置上逆变器触发的要求，研制了利用OMAPL138和FP-GA实现的多路PWM脉冲发生器。该脉冲发生器利用接口单元接收OMAPL138写入的PWM脉冲占空比和设置参数等数据，利用FPGA产生PWM波形，达到其工作不受OMAPL138影响的效果。同时介绍了脉冲发生器的硬件架构、基本原理和实现方法，并通过仿真和实验得到验证。该PWM发生器既简化了电路的设计，提高了系统的可靠性，又可保证逆变器功率元件触发的同步。
Three phase full wave dc motor decoder
Studer, P. A. (Inventor)
1977-01-01
A three phase decoder for dc motors is disclosed which employs an extremely simple six transistor circuit to derive six properly phased output signals for fullwave operation of dc motors. Six decoding transistors are coupled at their base-emitter junctions across a resistor network arranged in a delta configuration. Each point of the delta configuration is coupled to one of three position sensors which sense the rotational position of the motor. A second embodiment of the invention is disclosed in which photo-optical isolators are used in place of the decoding transistors.
FPGA Techniques Based New Hybrid Modulation Strategies for Voltage Source Inverters
Sudha, L. U.; J. Baskaran; Elankurisil, S. A.
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switch...
Variable speed wind turbine generator system with current controlled voltage source inverter
Energy Technology Data Exchange (ETDEWEB)
Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)
2011-07-15
highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.
Polycarbonate based three-phase nanocomposite dielectrics
Sain, P. K.; Goyal, R. K.; Prasad, Y. V. S. S.; Bhargava, A. K.
2016-08-01
Three-phase polycarbonate (PC) matrix nanocomposites are prepared using the solution method. One of the nanocomposite fillers is dielectric and the other is conducting. Lead zirconate titanate (PZT) is used as the dielectric filler. The conducting fillers, nano-Cu and multi-walled carbon nanotubes (MWCNTs), are used to make two different nanocomposites, MWCNT-PZT-PC and Cu-PZT-PC. The prepared nanocomposites are characterized using density measurement, x-ray diffractometry, scanning electron microscopy, energy dispersive x-ray spectroscopy, and differential scanning calorimetry. Percolation is absent in both three-phase nanocomposites within the study’s concentration window of conducting fillers. The dielectric properties of the nanocomposites are evaluated using a precision impedance analyser. The dielectric constant of the Cu-PZT-PC nanocomposite increases to 14 (a dissipation factor of 0.17), whereas in the case of the MWCNT-PZT-PC nanocomposite it increases to 8.5 (a dissipation factor of 0.002). The melting point of both nanocomposites decreases with respect to the control PC. The frequency (1 kHz to 1 MHz) and temperature (room temperature to 200 °C) dependence of the dielectric constant and dissipation factor are examined. For the Cu-PZT-PC nanocomposites, the dielectric constant decreases with increasing frequency, whereas in the case of the MWCNT-PZT-PC nanocomposites the dielectric constant is almost constant. The dielectric constant and dissipation factor exhibit a slight temperature dependence.
Directory of Open Access Journals (Sweden)
B. Santhosh Kumar
2014-02-01
Full Text Available This paper presents a novel structure for a three- phase four-wire (3P4W distribution system utilizing unified power quality conditioner (UPQC. The 3P4W system is realized from a three-phase three-wire system where the neutral of series transformer used in series part UPQC is considered as the fourth wire for the 3P4W system. A new control strategy to balance the unbalanced load currents is also presented in this paper. The neutral current that may flow toward transformer neutral point is compensated by using a four-leg voltage source inverter topology for shunt part. Thus, the series transformer neutral will be at virtual zero potential during all operating conditions. The simulation results based on MATLAB/Simulink are presented to show the effectiveness of the proposed UPQC-based 3P4W distribution system.
PWM Switching Strategy for Torque Ripple Minimization in BLDC Motor
Salah, Wael A.; Ishak, Dahaman; Hammadi, Khaleel J.
2011-05-01
This paper describes a new PWM switching strategy to minimize the torque ripples in BLDC motor which is based on sensored rotor position control. The scheme has been implemented using a PIC microcontroller to generate a modified Pulse Width Modulation (PWM) signals for driving power inverter bridge. The modified PWM signals are successfully applied to the next up-coming phase current such that its current rise is slightly delayed during the commutation instant. Experimental results show that the current waveforms of the modified PWM are smoother than that in conventional PWM technique. Hence, the output torque exhibits lower ripple contents.
2013-01-01
In three-phase photovoltaic (PV) system, three-phase filter inductors are important part for the output electrical power quality. The comparison analyses of three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors in three-phase PV inverter are proposed. Firstly, the three-phase PV inverter operation with discrete filter inductors is analyzed, and the design of discrete filter inductors is given; then operation of the three-phase PV inverter with three-ph...
Evaluation of Modulation Schemes for Three-Phase to Three-Phase Matrix Converters
DEFF Research Database (Denmark)
Helle, Lars; Larsen, Kim B.; Joergensen, Allan Holm
2004-01-01
This paper presents a method for evaluating different modulation schemes employed with three-phase to three-phase matrix converters. The evaluation method addresses three important modulator characteristics: the output waveform quality, the input waveform quality and the switching losses associated...... on the output load angle. This new modulation approach is applicable whenever the output voltage reference is below half the input voltage, and the output voltage quality is then superior to that of the conventional space vector modulation scheme. The functionality of the new modulation scheme is validated...
DEFF Research Database (Denmark)
Qu, Hao; Yang, Xijun; Guo, Yougui
2014-01-01
-sequence component injection, in order to reduce power loss and increased overall efficiency. And then by reconstructing the other two phase input voltages and currents, the transformation from stationary frame (abc) to rotating frame (dq frame) is designed. Finally, a PI regulator based controller for single......Single-phase voltage source converter (VSC) is an important power electronic converter (PEC), including single-phase voltage source inverter (VSI), single-phase voltage source rectifier (VSR), single-phase active power filter (APF) and single-phase grid-connection inverter (GCI). Single-phase VSC...
Directory of Open Access Journals (Sweden)
Ying Jiang
2013-01-01
Full Text Available In three-phase photovoltaic (PV system, three-phase filter inductors are important part for the output electrical power quality. The comparison analyses of three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors in three-phase PV inverter are proposed. Firstly, the three-phase PV inverter operation with discrete filter inductors is analyzed, and the design of discrete filter inductors is given; then operation of the three-phase PV inverter with three-phase integrated five-limb magnetic core filter inductors is analyzed, the design of integrated filter inductors with five-limb magnetic core is given, then the operation of three-phase PV inverter with three-phase integrated three-limb magnetic core filter inductors is analyzed, and the design of integrated filter inductors with three limbs magnetic core is given. The conclusion of comparison between three-phase discrete filter inductors and two kinds of three-phase integrated filter inductors is done; it means that the three-phase discrete filter inductors can achieve better output electrical power quality with lower power density and three-phase integrated filter inductors can achieve higher power density with lower output electrical power quality. Finally, the experiment results are given to compare the volume and filter effect of three kinds of filter inductors in three-phase PV inverter.
2014-01-01
In order to utilize the energy from the renewable energy sources, power conversion system is necessary, in which the voltage source inverter (VSI) is usually the last stage for injecting power to the grid. It is an economical solution to add the function of power quality conditioning to the grid-connected VSI in the low-voltage distribution system. Two multifunctional VSIs are studied in this paper, that is, inductive-coupling VSI and capacitive-coupling VSI, which are named after the fundame...
Analytical Method to Calculate the DC Link Current Stress in Voltage Source Converters
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus;
2014-01-01
The dc-link capacitor is one of the critical components, which influences the lifetime of the whole voltage source converter unit. For reliable design, the operating temperature of the dc-link capacitor should be known, which is primarily determined by the ambient temperature and the rms value...... of the current flowing through the dc-link capacitor. A simple analytical method to calculate the rms value of the dc-link capacitor current is presented in this paper. The effect of the line current ripple on the rms value of the dc-link capacitor current is considered. This yields accurate results, especially...
Virtual-Impedance-Based Control for Voltage-Source and Current-Source Converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Li, YunWei; Blaabjerg, Frede;
2015-01-01
The virtual impedance concept is increasingly used for the control of power electronic systems. Generally, the virtual impedance loop can either be embedded as an additional degree of freedom for active stabilization and disturbance rejection, or be employed as a command reference generator...... for the converters to provide ancillary services. This paper presents an overview of the virtual-impedance-based control strategies for voltage-source and current-source converters. The control output impedance shaping attained by the virtual impedances is generalized first using the impedance-based models...
Stability analysis and design of the improved droop controller on a voltage source inverter
DEFF Research Database (Denmark)
Calabria, Mauro; Schumacher, Walter; Guerrero, Josep M.;
2015-01-01
This paper studies the dynamics of a droop-controlled voltage source inverter connected to a stiff grid and addresses the use of the improved droop controller in order to enhance the dynamic behavior of the system. The small-signal stability of the inverter is studied in depth considering...... variations on its droop parameters, providing a general understanding on the functioning of such system. Finally, three methods to tune the dynamic droop gain are introduced and compared, providing analytical, simulation, and experimental results....
High-performance feedback-type active damping of LCL-filtered voltage source converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
Active damping of LCL-filter resonance based on single-state feedback control is widely used with voltage source converters. Its robustness against grid impedance variation has always been a major concern with its controller design. To deal with this issue, this paper begins by developing......, but ensures also a robust stabilization against the grid parameters variations. For illustration, the approach is applied to design three single-state feedback-damping schemes, and their damping robustness are compared under both inductive and resonant grid impedances. Experimental results validate...
Modulation Technique for Four-Leg Voltage Source Inverter without a Look-Up Table
DEFF Research Database (Denmark)
Ebrahimzadeh, Esmaeil; Farhangi, Shahrokh; Iman-Eini, Hossein
2016-01-01
Three-dimensional space-vector modulation (3D SVM) has more popularity among the other modulation techniques of the four-leg inverter due to higher DC-link voltage utilisation. Sequencing schemes of the switching vectors in the 3D SVM are divided into Class I and II categories. Each...... of these classes itself has four kinds: (a) rising-edge aligned, (b) falling-edge aligned, (c) symmetrically aligned and (d) alternative sequence. In this study, implementation of the conventional 3D SVM technique in abc-coordinate for four-leg voltage source inverters is simplified, while it can be so easily...
Integrated modeling and control of a PEM fuel cell power system with a PWM DC/DC converter
Energy Technology Data Exchange (ETDEWEB)
Choe, Song-Yul; Ahn, Jong-Woo [Mechanical Engineering Department, Auburn University, Auburn, AL 36848 (United States); Lee, Jung-Gi [Electrical Engineering Department, Pohang University of Science and Technology, Pohang (Korea); Baek, Soo-Hyun [Electrical Engineering Department, Dong-guk University, Seoul (Korea)
2007-02-10
A fuel cell powered system is regarded as a high current and low voltage source. To boost the output voltage of a fuel cell, a DC/DC converter is employed. Since these two systems show different dynamics, they need to be coordinated to meet the demand of a load. This paper proposes models for the two systems with associated controls, which take into account a PEM fuel cell stack with air supply and thermal systems, and a PWM DC/DC converter. The integrated simulation facilitates optimization of the power control strategy, and analyses of interrelated effects between the electric load and the temperature of cell components. In addition, the results show that the proposed power control can coordinate the two sources with improved dynamics and efficiency at a given dynamic load. (author)
Design, Control, and Modeling of a New Voltage Source Converter for HVDC System
Mohan, Madhan; Singh, Bhim; Ketan Panigrahi, Bijaya
2013-05-01
Abstract: A New Voltage Source Converter (VSC) based on neutral clamped three-level circuit is proposed for High Voltage DC (HVDC) system. The proposed VSC is designed in a multipulse configuration. The converter is operated by Fundamental Frequency Switching (FFS). A new control method is developed for achieving all the necessary control aspects of HVDC system such as independent real and reactive power control, bidirectional real and reactive power control. The basic of the control method is varying the pulse width and by keeping the dc link voltage constant. The steady state and dynamic performances of HVDC system interconnecting two different frequencies network are demonstrated for active and reactive power control. Total number of transformers used in this system are reduced to half in comparison with the two-level VSCs for both active and reactive power control. The performance of the HVDC system is improved in terms of reduced harmonics level even at fundamental frequency switching. The harmonic performance of the designed converter is also studied for different value of the dead angle (β), and the optimized range of the dead angle is achieved for varying reactive power requirement. Simulation results are presented for the designed three level multipulse voltage source converters with the proposed control algorithm.
Institute of Scientific and Technical Information of China (English)
ESMAELI Abdolreza; SUN Li
2007-01-01
Modeling and simulation of induction motor drive system to investigate and mitigate the adverse effects of PWM inverter based on analysis, modeling and simulation are presented. The estimation of conducted disturbances and other adverse effects of PWM inverter by simulation offer a considerable gain from the economic point of view. For an accurate model of the motor drive system including mains, rectifier, inverter, motor and its long cables, the high frequency parasitic current paths are taken into account. The novel model and its parasitic values for three-phase induction motor system are presented. Finally a new solution for suppressing EMI, common mode voltage, leakage current, bearing current and shaft voltages is proposed and the results show the excellent performances of proposed solution including active and passive filters.
Energy Technology Data Exchange (ETDEWEB)
Machado, Ricardo Q.; Pomilio, Jose A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Fac. de Engenharia Eletrica e de Computacao], e-mail: ricardom@dsce.fee.unicamp.br; Buso, Simone [Universidade de Padova, Padua (Italy). Dept. de Engenharia da Informacao], e-mail: simone.buso@dei.unipd.it
2004-07-01
This paper describes a line-interactive single-phase to three-phase converter. The typical application is in rural areas supplied by the single-wire with earth return. The traditional objective of feeding a three-phase induction motor is not anymore the main concern for such conversion. Due to the evolution of the agro business, some of the local load (as electronic power converters, computers, communication equipment, etc.) requires high quality power, intended as sinusoidal, symmetrical and balanced three-phase voltage. Additionally, to maximize the power got from the feeder, the system provides a unitary power factor to the feeder. A three-phase PWM converter is used for this purpose. The power converter does not process all the load power, as in the conventional solutions, but only the fraction necessary to regulate the three-phase bus voltage. The control strategy, design highlights and experimental results are presented. (author)
基于PSIM的PWM逆变器通用仿真模型%The General Simulation Model of PWM Inverter on PSIM
Institute of Scientific and Technical Information of China (English)
赵春柳
2013-01-01
PWM（Pusle Width Modulation，PWM）逆变器的应用越来越广泛，而PWM逆变器的控制模式又多种多样，因此对于系统仿真而言，建立PWM逆变器的通用仿真模型就尤为重要。该文建立三相全桥PWM逆变器的仿真模型，通过仿真表明该模型具有结构简单、通用性好和仿真效率高的特点。%Application of PWM(Pusle Width Modulation,PWM)inverter is more and more extensive, and there are all kinds of control method of PWM inverter, so the establishment of general simulation model of PWM inverter is very important when sys?tem simulation is needed. A simualtion model of three-phase full bridge PWM converter is established in this paper, it is proved that the configuration of simulation model is simple, the generality of this model is good and the simulation efficiency is high.
Large-signal stability analysis of PWM converters
Energy Technology Data Exchange (ETDEWEB)
Huynh, P.T. [Philips Labs., Briarcliff Manor, NY (United States); Cho, B.H. [Seoul National Univ. (Korea, Republic of). Dept. of Electrical Engineering
1995-12-31
Investigation of the effects of existing nonlinearities on the stability of PWM converters is performed. The bilinear structure, the duty cycle saturation, and the opamp saturation are the principal nonlinearities in PWM converters. These nonlinearities are incorporated in the large-signal analytical models of PWM converters, and the basic input-output stability theory is applied to analyze their stability. Design and optimization of the small-signal loop gains to counteract the undesirable nonlinear effects are also discussed.
Institute of Scientific and Technical Information of China (English)
Juming CHEN; Feng LIU; Shengwei MEI
2006-01-01
Active power filter (APF) based on voltage source inverter (VSI) is one of the important measures for handling the power quality problem. Mathematically, the APF model in a power grid is a typical nonlinear one. The idea of passivity is a powerful tool to study the stabilization of such a nonlinear system. In this paper, a state-space model of the four-leg APF is derived, based on which a new H-infinity controller for current tracking is proposed from the passivity point of view. It can achieve not only asymptotic tracking, but also disturbance attenuation in the sense of L2-gain. Subsequently,a sufficient condition to guarantee the boundedness and desired mean of the DC voltage is also given. This straightforward condition is consistent with the power-balancing law of electrical circuits. Simulations performed on PSCAD platform verify the validity of the new approach.
Passivity-based design of robust passive damping for LCL-filtered voltage source converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2015-01-01
Passive damping is proven as a robust stabilizing technique for LCL-filtered voltage source converters. However, conventional design methods of passive dampers are based on the passive components only, while the inherent damping effect of time delay in the digital control system is overlooked....... In this paper, a frequency-domain passivity-based design approach is proposed, where the passive dampers are designed to eliminate the negative real part of the converter output admittance with closed-loop current control, rather than shaping the LCL-filter itself. Thus, the influence of time delay...... in the current control is included, which allows a relaxed design of the passive damper with the reduced power loss and improved stability robustness against grid parameters variations. Design procedures of two commonly used passive dampers with LCL-filtered VSCs are illustrated. Experimental results validate...
A Unified Impedance Model of Voltage-Source Converters with Phase-Locked Loop Effect
DEFF Research Database (Denmark)
Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede
2016-01-01
This paper proposes a unified impedance model for analyzing the effect of Phase-Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary αβ-frame by means of complex transfer functions...... and complex space vectors, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect in the phase domain. Thus, the impedance models previously developed in the different domains can be unified. Moreover, the impedance shaping effects of PLL are structurally...... characterized for the current control in the rotating dq-frame and the stationary αβ-frame. Case studies based on the unified impedance model are presented, which are then verified in the time-domain simulations and experiments. The results closely correlate with the impedance-based analysis....
Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter
Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim
2016-08-01
This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.
Estimation of the Plant Time Constant of Current-Controlled Voltage Source Converters
DEFF Research Database (Denmark)
Vidal, Ana; Yepes, Alejandro G.; Malvar, Jano;
2014-01-01
Precise knowledge of the plant time constant is essential to perform a thorough analysis of the current control loop in voltage source converters (VSCs). As the loop behavior can be significantly influenced by the VSC working conditions, the effects associated to converter losses should be included...... of the VSC interface filter measured at rated conditions. This paper extends that method so that both parameters of the plant time constant (resistance and inductance) are estimated. Such enhancement is achieved through the evaluation of the closed-loop transient responses of both axes of the synchronous...... in the model, through an equivalent series resistance. In a recent work, an algorithm to identify this parameter was developed, considering the inductance value as known and practically constant. Nevertheless, the plant inductance can also present important uncertainties with respect to the inductance...
Voltage source ac-to-dc converters for high-power transmitters
Cormier, R.
1990-01-01
This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.
An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability...... is assessed based on a series of Nyquist diagrams drawn for the terminal impedance of each converter. Thus, the effect of the right half-plane zeros of terminal impedances in the derivation of impedance ratio for paralleled source-source converters is avoided. The interaction between the terminal impedance...... of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical...
FPGA techniques based new hybrid modulation strategies for voltage source inverters.
Sudha, L U; Baskaran, J; Elankurisil, S A
2015-01-01
This paper corroborates three different hybrid modulation strategies suitable for single-phase voltage source inverter. The proposed method is formulated using fundamental switching and carrier based pulse width modulation methods. The main tale of this proposed method is to optimize a specific performance criterion, such as minimization of the total harmonic distortion (THD), lower order harmonics, switching losses, and heat losses. The proposed method is articulated using fundamental switching and carrier based pulse width modulation methods. Thus, the harmonic pollution in the power system will be reduced and the power quality will be augmented with better harmonic profile for a target fundamental output voltage. The proposed modulation strategies are simulated in MATLAB r2010a and implemented in a Xilinx spartan 3E-500 FG 320 FPGA processor. The feasibility of these modulation strategies is authenticated through simulation and experimental results.
Investigation of Grid-connected Voltage Source Converter Performance under Unbalanced Faults
DEFF Research Database (Denmark)
Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde
2016-01-01
Renewable energy sources (RES) and HVDC links are typically interfaced with the grid by power converters, whose performance during grid faults is significantly different from that of traditional synchronous generators. This paper investigates the performance of grid-connected voltage source...... that the performance of VSCs varies with their control strategies. Negative-sequence current control is necessary to restrict converter current in each phase under unbalanced faults. Among presented control strategies, the balanced current control strategy complies with the present voltage support requirement best...... converters (VSCs) under unbalanced faults. Conventional positive-sequence synchronous reference frame (SRF) control is presented first, followed by three different negative-sequence current control strategies considering reactive power injection and converter current limit. The simulation results indicate...
A low-power circuit for piezoelectric vibration control by synchronized switching on voltage sources
Shen, Hui; Ji, Hongli; Zhu, Kongjun; Balsi, Marco; Giorgio, Ivan; dell'Isola, Francesco
2010-01-01
In the paper, a vibration damping system powered by harvested energy with implementation of the so-called SSDV (synchronized switch damping on voltage source) technique is designed and investigated. In the semi-passive approach, the piezoelectric element is intermittently switched from open-circuit to specific impedance synchronously with the structural vibration. Due to this switching procedure, a phase difference appears between the strain induced by vibration and the resulting voltage, thus creating energy dissipation. By supplying the energy collected from the piezoelectric materials to the switching circuit, a new low-power device using the SSDV technique is proposed. Compared with the original self-powered SSDI (synchronized switch damping on inductor), such a device can significantly improve its performance of vibration control. Its effectiveness in the single-mode resonant damping of a composite beam is validated by the experimental results.
Apparatus and method for heat-run test on high-power PWM converters with low energy expenditure
Indian Academy of Sciences (India)
J S Siva Prasad; G Narayanan
2013-06-01
Before installation, a voltage source converter is usually subjected to heat-run test to verify its thermal design and performance under load. For heat-run test, the converter needs to be operated at rated voltage and rated current for a substantial length of time. Hence, such tests consume huge amount of energy in case of high-power converters. Also, the capacities of the source and loads available in the research and development (R & D) centre or the production facility could be inadequate to conduct such tests. This paper proposes a method to conduct heat-run tests on highpower, pulse width modulated (PWM) converters with low energy consumption. The experimental set-up consists of the converter under test and another converter (of similar or higher rating), both connected in parallel on the ac side and open on the dc side. Vector-control or synchronous reference frame control is employed to control the converters such that one draws certain amount of reactive power and the other supplies the same; only the system losses are drawn from the mains. The performance of the controller is validated through simulation and experiments. Experimental results, pertaining to heat-run tests on a high-power PWM converter, are presented at power levels of 25 kVA to 150 kVA.
Single-phase to three-phase power conversion interface
Wu, Jinn-Chang; Wang, Yung-Shan; Jou, Hurng-Liahng; Lu, Wei-Tso
2016-07-01
This study proposes a single-phase to three-phase power conversion interface which converts the power from a single-phase utility to three-phase power for a three-phase load. The proposed single-phase to three-phase power conversion interface comprises a bridge-type switch set, a set of three-phase inductors, a transformer set and a set of three-phase capacitors. A current-mode control controls the switching of bridge-type switch set, to generate a set of nonzero-sequence (NZS) currents and a set of zero-sequence (ZS) currents. The transformer set is used to decouple the NZS currents and the ZS currents. The NZS currents are used to generate a high-quality three-phase voltage that supplies power to a three-phase load. The ZS currents flow to the single-phase utility so that the utility current is sinusoidal and in phase with the utility voltage. Accordingly, only a bridge-type switch set is used in the single-phase to three-phase power conversion interface to simply the power circuit. A prototype is developed and tested to verify the performance of the proposed single-phase to three-phase power conversion interface.
Simulation of Five Phase Voltage Source Inverter with Different Excitation for Star Connected Load
Directory of Open Access Journals (Sweden)
M.A Inayathullaah
2014-07-01
Full Text Available In order to reduce the torque ripple and harmonics for smooth operation of the machine and to reduce the amount of heat generated the motor has to be supplied with multi phase supply greater than three phase supply. Selection of even number of phases should be avoided, because it decreases the performance of the motor as poles coincide with each other. So, Five Phase Supply is preferred. A five phase five leg 10 switch inverter fed five phase star connected load operating with five different excitation is simulated and compared with that of three phase conventional inverter.
Directory of Open Access Journals (Sweden)
BOTEZAN, A.
2015-08-01
Full Text Available The paper presents the hysteresis current control of the voltage source inverter. The eMEGAsim real-time simulator is developed by OPAL-RT. Real-time simulation is used in many cases because it allows the behavior of the industrial processes operation to be determined. Two research directions are developed in this case, Rapid Control Prototyping and Hardware-In-the-Loop. Using eMEGAsim simulator allows implementing the command and control strategy of a single-phase voltage source inverter. At this stage, the real-time behavior of operation is monitored, because the voltage source inverter will be the part of a single-phase shunt active filter. In order to command and control the voltage source inverter, the current and voltage signals are acquired, since these signals are necessary to estimate reference signal. Extension of the Instantaneous Reactive Power Theorem is used because this theorem is suitable for single-phase active filter control. To test the real-time command and control strategy implemented, it was used a low power single-phase voltage source inverter (full bridge.
Full Bridge ZVT—PWM DC—DC Converter①
Institute of Scientific and Technical Information of China (English)
WEIYanjun; QIHanhong; 等
1997-01-01
A new FB-ZVT-PWM converter is proposed.The new converter operates at a fixed frequency and implements ZVS for power devices without increasing voltage in both turn-on and turn-off transient.A 80kHz/50 W FB-ZVT-PWM boost converter using MOSFETs is analysed theoretically.
System For Characterizing Three-Phase Brushless dc Motors
Howard, David E.; Smith, Dennis A.
1996-01-01
System of electronic hardware and software developed to automate measurements and calculations needed to characterize electromechanical performances of three-phase brushless dc motors, associated shaft-angle sensors needed for commutation, and associated brushless tachometers. System quickly takes measurements on all three phases of motor, tachometer, and shaft-angle sensor simultaneously and processes measurements into performance data. Also useful in development and testing of motors with not only three phases but also two, four, or more phases.
Llopis, Francisco
2013-01-01
The circuit presented in this paper aims at providing three 40 Vpp 50Hz AC voltages sources with 120-degree phase separation between them. This is a fully analogue circuit that uses standard, low-cost electronic components without resorting to a microcontroller as previously proposed by Shirvasar et al [1]. This circuit may serve as a basis for a low-voltage 3P-AC power supply that students may safely use to realize experiments, i.e. about the principles and applications of three-phase AC power lines, without the risk of electric shocks.
Digital Computer Transient Models of Three-Phase Inverter Systems Under Normal and Fault Conditions
Gawish, Said Abdelhamid Atiya
In many industrial applications, variable speed drives of electrical machines are needed. This speed control can be met either by dc or ac machines. The ac machines have several distinct advantages compared to dc machines due to the absence of commutators, therefore, a variable -voltage, variable-frequency power supply is normally required for speed control of ac machines. This power supply can be obtained by a dc link converter system that consists of a rectifier and inverter. In this dissertation the waveforms and transient response of a three-phase forced-commutated inverters are simulated on a digital computer from basic circuit theory. Both the voltage source inverter (VSI) and the current source inverter (CSI) are simulated using thyristors with real characteristics. The simulation is further modified to give three-phase currents with adjustable frequency to be used in adjustable speed induction motor drives or the starting of synchronous motors from rest. The digital simulation of Gate Turn-Off (GTO) thyristor inverters feeding an induction motor is presented and can allow for step frequency change for the study of adjustable speed induction motor drives. A naturally-commutated three-phase inverter using thyristors with real characteristics was also simulated to study VSIs and CSIs. The interactions between the load parameters and the inverter circuit parameters are investigated. The parameters studied include ratio of dc voltage to amplitude of ac voltage, ratio of smoothing inductance to load inductance and triggering angle (alpha). Since the naturally-commutated CSI system is widely used in power applications, it was investigated under different types of fault s occurring both on the line and in the inverter circuit. These faults include three-phase short circuits, thyristor failures, line-to-line faults, false triggering and open circuits. A digital computer was used to simulate these faults and the system response because it is difficult to obtain the
Design of the Three-Phase Static Converter%一种三相静止变流器设计
Institute of Scientific and Technical Information of China (English)
张西虎
2001-01-01
This paper introduces a three-phase static converterwith high frequency PWM technique, it realizes DC/DC withBoost converter, and inverter is fulfilled by 120 degree on-timeinverter, and also designs AC filter circuit, the output wave-form become sine wave.%论述的三相静止变流器采用高频PWM技术，利用Boost变换器实现直流升压，然后由120°导通型逆变器完成逆变，并设计了交流滤波电路，使输出波形为正弦波。
Directory of Open Access Journals (Sweden)
Bogimi Sirisha
2012-03-01
Full Text Available In this paper, a three-phase two leg neutral point clamped (NPC converter is presented for power factor correction and dc-link voltage regulation. The adopted converter has simpler circuit configuration and less number of power switches compared to three-level PWM converter. In this circuit configuration, only eight power switches and four clamping diodes with voltage stress of half the dc bus voltage are used. A simplified space vector pulse width modulation scheme (SVPWM is also adopted to track the line current commands. A reference voltage vector is generated on the ac terminal for drawing the sinusoidal line currents with unity power factor. This algorithm reduces the time required to calculate the switching time durations of voltage vectors. The simulation results have been presented to verify the validity and effectiveness of the proposed control strategy.
A New Topology of Three-Phase Four-Wire UPQC with a Simplified Control Algorithm
Directory of Open Access Journals (Sweden)
Yash Pal
2012-03-01
Full Text Available In this paper, a simplified control algorithm based on unit vector template generation (UVTG is proposed for a star-delta supported three-phase four-wire (3P-4W unified power quality conditioner (UPQC topology for the improvement of different power quality problems. Different topologies reported in literature for 3P-4W UPQC use active compensation for the mitigation of source neutral current along with other power quality (PQ problems, while the uses of passive elements for the mitigation of source neutral current are advantageous over the active compensation due to ruggedness and less complexity of control. Hence, in this paper a star-delta transformer is connected in shunt near the load for mitigation of source neutral current, while three-leg voltage source inverters (VSIs based shunt and series active power filters (APFs of 3P-4W UPQC mitigate the current and voltage based distortions, respectively. A simple control algorithm based on Unit Vector Template Generation (UVTG is used as a control strategy of UPQC for mitigation of different PQ problems. In this control scheme, the current/voltage control is applied over the fundamental supply currents/load voltages instead of fast changing APFs currents/voltages, thereby reducing the effects of computational delay and the required sensors. The performance of the proposed topology of UPQC is analyzed through simulations results using MATLAB software with its Simulink and Power System Block set toolboxes.
Push-Pull Converter Fed Three-Phase Inverter for Residential and Motor Load
Directory of Open Access Journals (Sweden)
Samuel Rajesh Babu
2015-06-01
Full Text Available The proposed paper is an new approach for power conditioning of a PV (photo-voltaic cell array. The main objective is to investigate an approach to provide and improve the delivered electric energy by means of power conditioning structures with the use of alternative renewable resources (ARRs for remote rural residential or industrial non-linear loads. This approach employs a series-combined connected boost and buck boost DC-DC converter for power conditioning of the dc voltage provided by a photo-voltaic array. The input voltage to the combined converters is 100 V provided from two series connected PV cells, which is converted and increased to 200 V at the dc output voltage. Series-combined connected boost and buck-boost DC-DC converters operate alternatively. This helps to reduce the input ripple current and provide the required 400 Vdc on a sinusoidal PWM three-phase inverter. Analysis of the two series-combined DC-DC converters is presented along with simulation results. Simulations of the series-combined DC-DC converters are presented with an output DC voltage of 200 V and a maximum output load of Po = 600 W.
Directory of Open Access Journals (Sweden)
Wenzhou Lu
2016-01-01
Full Text Available This paper analyzes the general properties of IMP-based controller and presents an internal-model-principle-based (IMP-based specific harmonics repetitive control (SHRC scheme. The proposed SHRC is effective for specific nk±m order harmonics, with n>m≥0 and k=0,1,2,…. Using the properties of exponential function, SHRC can also be rewritten into the format of multiple resonant controllers in parallel, where the control gain of SHRC is n/2 multiple of that of conventional RC (CRC. Therefore, including SHRC in a stable closed-loop feedback control system, asymptotic disturbance eliminating, or reference tracking for any periodic signal only including these specific harmonic components at n/2 times faster error convergence rate compared with CRC can be achieved. Application examples of SHRC controlled three-phase/single-phase grid-connected PWM inverters demonstrate the effectiveness and advantages of the proposed SHRC scheme.
Directory of Open Access Journals (Sweden)
NingYi Dai
2014-01-01
Full Text Available In order to utilize the energy from the renewable energy sources, power conversion system is necessary, in which the voltage source inverter (VSI is usually the last stage for injecting power to the grid. It is an economical solution to add the function of power quality conditioning to the grid-connected VSI in the low-voltage distribution system. Two multifunctional VSIs are studied in this paper, that is, inductive-coupling VSI and capacitive-coupling VSI, which are named after the fundamental frequency impedance of their coupling branch. The operation voltages of the two VSIs are compared when they are used for renewable energy integration and power quality conditioning simultaneously. The operation voltage of the capacitive-coupling VSI can be set much lower than that of the inductive-coupling VSI when reactive power is for compensating inductive loads. Since a large portion of the loads in the distribution system are inductive, the capacitive-coupling VSI is further studied. The design and control method of the multifunctional capacitive-coupling VSI are proposed in this paper. Simulation and experimental results are provided to show its validity.
Dai, NingYi; Lam, Chi-Seng; Zhang, WenChen
2014-01-01
In order to utilize the energy from the renewable energy sources, power conversion system is necessary, in which the voltage source inverter (VSI) is usually the last stage for injecting power to the grid. It is an economical solution to add the function of power quality conditioning to the grid-connected VSI in the low-voltage distribution system. Two multifunctional VSIs are studied in this paper, that is, inductive-coupling VSI and capacitive-coupling VSI, which are named after the fundamental frequency impedance of their coupling branch. The operation voltages of the two VSIs are compared when they are used for renewable energy integration and power quality conditioning simultaneously. The operation voltage of the capacitive-coupling VSI can be set much lower than that of the inductive-coupling VSI when reactive power is for compensating inductive loads. Since a large portion of the loads in the distribution system are inductive, the capacitive-coupling VSI is further studied. The design and control method of the multifunctional capacitive-coupling VSI are proposed in this paper. Simulation and experimental results are provided to show its validity.
Teruya, Daisuke; Masukawa, Shigeo; Iida, Shoji
We propose a novel inverter that can be operated either as a Current Source Inverter (CSI) or as a Voltage Source Inverter (VSI) by changing only the control signals. It is proper to apply it to the interconnecting system with renewal energy, such as photovoltaic cells or wind generation systems, to a grid. This inverter is usually operated as the CSI connected to the grid. Even if the energy source has a lower voltage than the grid, the energy can be supplied to the grid through the proposed inverter. The power factor can be briefly maintained at almost unity. When power supply from the grid is interrupted, the proposed circuit should be operated as the VSI in the stand-alone operation mode. In this way, the circuit can maintain a constant output voltage to the loads. In this paper, the proposed circuit configuration and the control schemes for both the CSI and the VSI are described. Further, the circuit characteristics for both are discussed experimentally.
Power angle control of grid-connected voltage source converter in a wind energy application
Energy Technology Data Exchange (ETDEWEB)
Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering
1995-12-31
In this thesis, the connection of a voltage source converter to the grid in a wind energy application is examined. The possibility of using a cheap control system without grid current measurements, is investigated. The control method is based on controlling the voltage angle of the inverter, which governs the active power flow. The highest frequency of the power variation, coming from wind turbine, is approx. 5 Hz. Since the proposed control method easily can handle such power variations it is very well suited for wind turbine applications. The characteristics of the system depend on the DC-link capacitor, the grid filter inductance and resistance. Large values of the resistance damp the system well but increase the energy losses. A high inductance leads to a reduced harmonic level on the grid but makes the system slower. By using feed-forward of the generator/rectifier current signal, the performance is increased compared to an ordinary PI-control. Combining the Linear Quadratic (LQ) control method with Kalman filtered input signals, a robust control method with a good performance is obtained. The LQ controller controls both the phase displacement angle and the modulation index, resulting in higher bandwidth, and the typical power angle resonance at the grid frequency disappears. 22 refs, 109 figs, 14 tabs
Nonlinear control of voltage source converters in AC-DC power system.
Dash, P K; Nayak, N
2014-07-01
This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations.
Effect of embedded voltage source converter on power system oscillation damping
Institute of Scientific and Technical Information of China (English)
R; DUNN
2010-01-01
This paper presents the damping torque analysis of power system oscillation stability as affected by the dynamic and control functions of an embedded voltage source converter(VSC).The objective of the study is to explain why and how the dynamic and basic control functions of the embedded VSC,ac and dc voltage regulation,provide damping to power system oscillations.The most important conclusion obtained in the paper is that both the dynamics and the dc voltage control of the VSC contribute a variable damping torque,which can be positive or negative,at different levels of system load conditions.More positive damping torque can be provided by the VSC at a heavier load condition.There exists a point of system load condition where the VSC provides no damping torque to power system oscillation hence dose not impose any influence on power system oscillation stability.The VSC studied in the paper can be the power-electronics-based interface of various FACTS(flexible ac transmission systems) devices,energy storage systems and renewable power generation units,although the focus of the discussion presented in this paper is the effect of the dynamics and basic control functions of the VSC themselves on power system oscillation damping.To demonstrate the analytical conclusions obtained in the paper,results of eigenvalue computation and nonlinear simulation of an example power system with STATCOM(static synchronous compensator) are given.
Improved Passive-Damped LCL Filter to Enhance Stability in Grid-Connected Voltage-Source Converters
DEFF Research Database (Denmark)
Beres, Remus Narcis; Wang, Xiongfei; Blaabjerg, Frede;
2015-01-01
This paper proposes an improved passive-damped LCL filter to be used as interface between the grid-connected voltage-source converters and the utility grid. The proposed filter replaces the LCL filter capacitor with a traditional C-type filter with the resonant circuit tuned in such a way that sw...
Directory of Open Access Journals (Sweden)
Chen Guoqiang
2016-01-01
Full Text Available Aiming at analysis complexity, a simulation model is built and presented to analyze and demonstrate the characteristics of the direct current (DC link current of the three-phase two-level inverter with the random space vector pulse width modulation (SVPWM strategy. The developing procedure and key subsystems of the simulation model are given in detail. Several experiments are done using the simulation model. The results verify the efficiency and convenience of the simulation model and show that the random SVPWM scheme, especially the random switching frequency scheme, can efficiently suppress the harmonic peaks of the DC link current.
PWM调制下无刷直流电机的转矩脉动抑制%Torque Ripple Reduction of Brushless DC Motors by PWM Modes
Institute of Scientific and Technical Information of China (English)
孟光伟; 李槐树; 熊浩
2011-01-01
分析无刷直流电机在PWM调制下稳态时的换相过程,通过在换相期间的PWM调制来实现高、低速条件下的换相转矩脉动补偿控制,确定了保持换相期间非换相相电流幅值不变的换相时间.分析PWM调制方式对三相六状态二二导通无刷直流电机控制系统的影响,提出了在PWM-ON-PWM调制方式下的换相转矩脉动补偿控制,不但能够完全消除非换相期间由于关断相出现电流而引起的电磁转矩脉动,而且能够完全补偿由于换相而引起的转矩脉动,实现电机在低速和高速时的无转矩脉动控制.%The steady commutation process of brushless DC motor by PWM modes was analyzed, and realized phase conversion torque ripple compensation control under both low speed and high speed operation by PWM control in commutation period,and confirmed commutation time to hold amplitude of current in commutation period. The effect by PWM modes on a three-phase six-state 120°conduction brushless DC motor was analyzed,and proposed torque ripple compensation control in PWM_ON_PWM mode, which can not only entirely eliminate torque ripple resulted from the current emerging in the turn-off phase during non-commutation period but also compensate torque ripple caused by the commutation current during commutation period. The torque ripple can be effectively reduced under both low speed and high speed operation using torque ripple compensation control in PWM ON PWM mode.
Three-phase tectonic evolution of the Andaman backarc basin
Digital Repository Service at National Institute of Oceanography (India)
KameshRaju, K.A
A three-phase evolutionary scheme since Late Oligocene for the Andaman backarc basin is proposed based on the multibeam swath bathymetry, magnetic and seismological data. A SW–NE trending spreading ridge bisects the basin. The tectonic evolution...
Energy Technology Data Exchange (ETDEWEB)
Singh, Bhim; Kasal, Gaurav Kumar [Department of Electrical Engineering, Indian Institute of Technology, Delhi, Hauz-Khas, New Delhi 110016 (India)
2008-06-15
This paper deals with a neural network-based solid state voltage controller for an isolated asynchronous generator (IAG) driven by constant speed prime mover like diesel engine, bio-gas or gasoline engine and supplying three-phase four-wire loads. The proposed control scheme uses an indirect current control and a fast adaptive linear element (adaline) based neural network reference current extractor, which extracts the real positive sequence current component without any phase shift. The neutral current of the source is also compensated by using three single-phase bridge configuration of IGBT (insulated gate bipolar junction transistor) based voltage source converter (VSC) along-with single-phase transformer having self-supported dc bus. The proposed controller provides the functions as a voltage regulator, a harmonic eliminator, a neutral current compensator, and a load balancer. The proposed isolated electrical system with its controller is modeled and simulated in MATLAB along with Simulink and PSB (Power System Block set) toolboxes. The simulated results are presented to demonstrate the capability of an isolated asynchronous generating system driven by a constant speed prime mover for feeding three-phase four-wire loads. (author)
Maetani, Tatsuo; Isomura, Yoshinori; Watanabe, Akihiko; Iimori, Kenichi; Morimoto, Shigeo
This paper describes an ungrounded common-mode equivalent circuit for a motor driven by a voltage-source PWM inverter. When the capacitance of the rotor was is small, the reversal of the polarities of the common-mode voltage and shaft voltage is observed. In order to model this reversal, a bridge-type equivalent circuit is proposed. On the basis of calculations and experiment, it is found the values and polarity of the shaft voltage can be are accurately determined with the proposed equivalent circuit. Furthermore, the capacitance value of the insulated rotor required to make the shaft voltage equal to or less than the dielectric breakdown voltage of the bearing grease is obtained.
Energy Technology Data Exchange (ETDEWEB)
She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William
2016-12-13
A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.
VFT PHASE VOLTAGE MEASUREMENT IN THREE-PHASE ENCLOSED GIS
Institute of Scientific and Technical Information of China (English)
邹建华; 岳子丁; 李洋
2002-01-01
The measuring of VFT phase voltage in three-phase enclosed GIS is more complex and difficult than in single-phase ones. There are 3 capacitive sensors in the measuring system, the outputs of which are with a linear relation to the three phase voltages. This linear relation is presented with a factorial matrix. Because each capacitive sensor is coupled with the electric field of three phases (A, B, and C), the electric coupling coefficients are introduced. In order to determine the matrix of electric coupling coefficients, the numerical calculation method can be used. From the discussion on two types of three-phase enclosed GIS bus, i.e. standard arrangement and biased arrangement, the dominant electric coupling coefficients are named, which can be simply and approximately calculated by an analytic expression. Finally, as an example, the waveforms of VFT phase voltage generated on a three-phase enclosed GIS bus model are displayed. When a capacitive sensor is located at the 'shortest point' of phase A (or B, or C), the VFT phase voltage VA (or VB, or VC) can almost be measured by that capacitive sensor alone.
Three-phase multilevel solar inverter for motor drive system
Bhasagare, Mayuresh P.
This thesis deals with three phase inverters and the different control strategies that can be associated with an inverter being used together. The first part of this thesis discusses the present research in the fields of PV panels, motor drive systems and three phase inverters along with their control. This control includes various strategies like MPPT, Volts-Hertz and modulation index compensation. Incorporating these techniques together is the goal of this thesis. A new topology for operating an open end motor drive system has also been discusses, where a boost converter and a flyback converter have been used in cascade to run a three phase motor. The main advantage of this is increasing the number of levels and improving the quality of the output voltage, not to mention a few other benefits of having the proposed circuit. A new algorithm has also been designed for starting and stopping the motor, which controls the current drawn from the power source during starting.
Single-to-three phase induction motor sensorless drive system
Directory of Open Access Journals (Sweden)
Z.M.S. El-Barbary
2012-06-01
Full Text Available This paper presented a single to three-phase induction motor drive system to provide variable output voltage and frequency. The proposed drive system employs only six IGBT switches, which form the front-end rectifier and the output inverter for the one step conversion from single-phase supply to output three-phase supply. The front-end rectifier permits bidirectional power flow and provides excellent regulation against fluctuations in source voltage. Moreover, it incorporates active input current shaping feature. The control strategy of the proposed drive system of three-phase induction motor is based on speed sensorless vector control technique. A low cost of motor drive and much more advantages can be achieved using the proposed drive system. Simulation and experimental results are carried out to analysis and explore the characteristics of the proposed drive system.
Research on three-phase unbalanced distribution network reconfiguration strategy
Hu, Shuang; Li, Ke-Jun; Xu, Yanshun; Liu, Zhijie; Guo, Jing; Wang, Zhuodi
2017-01-01
With the development of social economy, the loads installed in the distribution network become more and more complex which may cause the three-phase unbalance problems. This paper proposes an optimal reconfiguration approach based on mixed integer quadric programming (MIQP) method to address the three-phase unbalance problem. It aims to minimize the total network losses of the system. By using several square constraints to substitute the circular constraint, the original optimization problem is linearized and converted into a mixed-integer linear programming (MILP) model. Then this MILP problem is solved in general algebraic model system (GAMS) software using CPLEX solver. The additional losses caused by three-phase unbalanced are also considered. An IEEE 34 nodes test system is used to demonstrate the feasibility and effectiveness of the proposed method. The results show that the losses and the voltage violation mitigation in the network can be reduced significantly.
Three-phase bone scintigraphy in Pellegrini-Stieda disease.
Liu, R S; Chou, C S; Yeh, S H
1987-01-01
In a patient with Pellegrini-Stieda disease, radiographs of the knees were unremarkable at the time the three-phase bone scintigraphy was abnormal. The results of follow-up radiographs three months later remained normal in the left knee, where local steroid injection was given, but revealed typical positive results in the right knee with no treatment. The three-phase bone scintigraphic pattern is rather typical and antedates the radiographic changes. Thus, the radionuclide technique would provide a useful procedure for the early diagnosis and treatment of Pellegrini-Stieda disease.
Research of Hybrid Three-phase equilibrium Technology
Xu, K.; Liu, Z. Z.; Qi, G. Z.; Hou, Y. J.
2016-08-01
This paper puts forward a kind of managerial method based on the combination of PPF (passive power filter) and APF (active power filter) for the problem of three-phase current balance in three-phase four-wire system. This method uses two special reactors to filter zero- sequence current and uses APF to filter negative-sequence fundamental current, positive- sequence and negative-sequence harmonic current. It is more effective, reliable and economic. This paper proves feasibility of the method by the simulation results.
EMC Increasing of PWM Rectifier in Comparison with Classical Rectifier
Directory of Open Access Journals (Sweden)
R. Dolecek
2008-12-01
Full Text Available Pulse width modulated rectifier is a very popular topic nowadays. The modern industrial production demands continuous and lossless conversion of electrical energy parameters. This need leads to wide spread of power semiconductor converters. The rapid development in power electronics and microprocessor technology enables to apply sophisticated control methods that eliminate negative side effects of the power converters on the supply network. The phase controlled thyristor rectifiers overload the supply network with higher harmonics and reactive power consumption. That is why the PWM rectifier is being examined. In comparison with the phase controlled rectifier it can be controlled to consume nearly sinusoidal current with power factor equal to unity. Another advantage is its capability of energy recuperation. The PWM rectifier can assert itself for its good behavior in many applications, for example as an input rectifier in indirect frequency converter, or in traction. Traction vehicles equipped with PWM rectifier do not consume reactive power, do not load the supply network with higher harmonics, and the recuperation is possible. The paper deals with the PWM rectifier functional model realization and examination. Electromagnetic compatibility of PWM rectifier and classical phase controlled rectifier is compared on the basis of the input current harmonic analysis.
Noise Shaping Filter Compensating PWM Distortion for Fully Digital Amplifier
Yoneya, Akihiko
The full-digital audio amplifiers have several merits such as a high power enabling a small size of the amplifier and digital implementation of the signal processing which allows desired precision of the processing except for the final stage switching amplifiers. Unfortunately, the pulse width modulation (PWM) causes signal distortions because of the non-linearity of the modulation from the viewpoint of the transient response. This paper proposes a compensation method of the PWM distortion with feedback approach. In the noise-shaping filter of the delta-sigma modulator to calculate the pulse codes for the PWM, the distortion caused by the PWM is evaluated and fed it back to compensate the distortion. Eventually the filter is implemented as a state-variable filter with non-linear feedback from the quantizer. The calculation of the filter elements is also described. By using proposed filters, PWM signals with small distortions and small floor noise can be obtained to realize high-fidelity audio amplifiers.
Losses in armoured three-phase submarine cables
DEFF Research Database (Denmark)
Ebdrup, Thomas; Silva, Filipe Miguel Faria da; Bak, Claus Leth
2014-01-01
The number of offshore wind farms will keep increasing in the future as a part of the shift towards a CO2 free energy production. The energy harvested from the wind farm must be brought to shore, which is often done by using a three-phase armoured submarine power cable. The use of an armour...
Overhead three-phase transmission lines - Non-diagonalizable situations
Energy Technology Data Exchange (ETDEWEB)
Faria, J.A.B. (Centro de Electrotecnia da U.T.L. - Instituto Superior Tecnico, 1096 Lisboa (PT))
1988-10-01
Physically realizable transmission lines exist to which the standard modal theory does not apply since the ZY diagonalization cannot always be undertaken successfully. In this paper the non-diagonalizing conditions for typical overhead three-phase lines are established. Algorithms are described and implemented to synthesize concrete non-diagonalizable configurations, numerical examples being presented and discussed.
Lattice Boltzmann modeling of three-phase incompressible flows
Liang, H.; Shi, B. C.; Chai, Z. H.
2016-01-01
In this paper, based on multicomponent phase-field theory we intend to develop an efficient lattice Boltzmann (LB) model for simulating three-phase incompressible flows. In this model, two LB equations are used to capture the interfaces among three different fluids, and another LB equation is adopted to solve the flow field, where a new distribution function for the forcing term is delicately designed. Different from previous multiphase LB models, the interfacial force is not used in the computation of fluid velocity, which is more reasonable from the perspective of the multiscale analysis. As a result, the computation of fluid velocity can be much simpler. Through the Chapman-Enskog analysis, it is shown that the present model can recover exactly the physical formulations for the three-phase system. Numerical simulations of extensive examples including two circular interfaces, ternary spinodal decomposition, spreading of a liquid lens, and Kelvin-Helmholtz instability are conducted to test the model. It is found that the present model can capture accurate interfaces among three different fluids, which is attributed to its algebraical and dynamical consistency properties with the two-component model. Furthermore, the numerical results of three-phase flows agree well with the theoretical results or some available data, which demonstrates that the present LB model is a reliable and efficient method for simulating three-phase flow problems.
A cascaded three-phase symmetrical multistage voltage multiplier
Energy Technology Data Exchange (ETDEWEB)
Iqbal, Shahid [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Singh, G K [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Besar, R [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Muhammad, G [Faculty of Information Science and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)
2006-10-15
A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM.
Neural network based PWM AC chopper fed induction motor drive
Directory of Open Access Journals (Sweden)
Venkatesan Jamuna
2009-01-01
Full Text Available In this paper, a new Simulink model for a neural network controlled PWM AC chopper fed single phase induction motor is proposed. Closed loop speed control is achieved using a neural network controller. To maintain a constant fluid flow with a variation in pressure head, drives like fan and pump are operated with closed loop speed control. The need to improve the quality and reliability of the drive circuit has increased because of the growing demand for improving the performance of motor drives. With the increased availability of MOSFET's and IGBT's, PWM converters can be used efficiently in low and medium power applications. From the simulation studies, it is seen that the PWM AC chopper has a better harmonic spectrum and lesser copper loss than the Phase controlled AC chopper. It is observed that the drive system with the proposed model produces better dynamic performance, reduced overshoot and fast transient response. .
Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage
DEFF Research Database (Denmark)
Oleschuk, Valentin; Blaabjerg, Frede
2002-01-01
PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM...
SYNTHESIS OF VOLTAGES OF UNIFORM PWM IN TIME REGULATION
Directory of Open Access Journals (Sweden)
A. G. Stryzhniou
2014-01-01
Full Text Available The article describes a process of synthesis and qualitative assessment of the harmonic composition of voltages of multiple and single PWM pulses in time regulation, being, along with amplitude, frequency and phase method, one of control methods of an asynchronous motor. The main point of time regulation is that a pause after any two single PWM pulses with different polarity or after any two groups of multiple PWM pulses with different polarity changes during a process of regulation. Feature of time regulation is that a motor has fast response in the range of small-signal of control and good linearity of speed-torque characteristics in the whole control range. Analytical expressions of parameters of PWM pulses ai and ti are obtained which allow to simplify considerably a process of formation and implementation of time regulation using tabular or indexed-tabular methods. These expressions allow not only to define voltage amplitude of harmonic but also to perform qualitative assessment of harmonic composition of output voltages at time regulation. It is specified that harmonic frequencies wi = w0/q change in inverse proportion to magnitude of parameter q during a process of regulation and there is a replacement of a fundamental frequency by frequencies of higher harmonics.The offered approach allows to synthesize voltage of uniform single and multiple PWM pulses and to perform their comparative and qualitative analysis and the obtained expressions can be used at modeling of AC motor work. Voltage of multiple PWM pulses which is formed using stepped reference voltage with even quantity of steps in a half period and a pause on a zero level has the best parameters by criterion of a minimum of harmonic components and a maximum of a factor of anharmonicity Kнс at time regulation.
DEFF Research Database (Denmark)
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2014-01-01
This paper addresses the interaction between harmonic resonant controllers and active damping of LCL resonance in voltage source converters. A virtual series R-C damper in parallel with the filter capacitor is proposed with the capacitor current feedback loop. The phase lag resulting from the dig...... crossover frequency defined by the proportional gain of current controller. This is of particular interest for high-performance active harmonic filtering applications and low-pulse-ratio converters. Case studies in experiments validate the theoretical analysis....
Grid-Current-Feedback Active Damping for LCL Resonance in Grid-Connected Voltage-Source Converters
Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang
2016-01-01
This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis in the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is equivalent to adding a virtual impedance across the grid-side inductance. This added impedance is more precisely represented by a series RL branch in parallel with a negative inductance. The negative inductance helps...
Design of A 0.5V Op-Amp Based on CMOS Inverter Using Floating Voltage Sources
Wang, Jun; Lee, Tuck-Yang; Kim, Dong-Gyou; Matsuoka, Toshimasa; Taniguchi, Kenji
2008-01-01
This letter presents a 0.5 V low-voltage op-amp in a standard 0.18 µm CMOS process for switched-capacitor circuits. Unlike other two-stage 0.5 V op-amp architectures, this op-amp consists of CMOS inverters that utilize floating voltage sources and forward body bias for obtaining high-speed operation. And two improved common-mode rejection circuits are well combined to achieve low power and chip area reduction. Simulation results indicate that the op-amp has an open-loop gain of 62 dB, and a h...
Directory of Open Access Journals (Sweden)
Riyadh G. Omar
2014-12-01
Full Text Available Four-leg voltage source inverter is an evolution of the three-leg inverter, and was ought about by the need to handle the non-linear and unbalanced loads. In this work Matlab/ Simulink model is presented using space vector modulation technique. Simulation results for worst conditions of unbalanced linear and non-linear loads are obtained. Observation for the continuity of the fundamental inverter output voltages vector in stationary coordinate is detected for better performance. Matlab programs are executed in block functions to perform switching vector selection and space vector switching.
Zhang, Jianghan; Luo, Hui; Zhao, Jin; Wu, Feng
2015-02-01
This paper develops a novel method for the detection and isolation of open-transistor faults in voltage-source inverters feeding induction motors. Based on analyzing the load currents trajectories after Concordia transformation, six diagnostic signals each of which indicates a certain switch are extracted and a fuzzy rule base is designed to perform fuzzy reasoning in order to detect and isolate 21 fault modes including single- and double-transistor faults. In addition, the fuzzy rules are rearranged and each of them is set to a reasonable value representing the fault modes. The simulation and experiment are carried out to demonstrate the effectiveness of the proposed fuzzy approach.
Phase-lock loop of Grid-connected Voltage Source Converter under non-ideal grid condition
DEFF Research Database (Denmark)
Wang, Haojie; Sun, Hai; Han, Minxiao;
2015-01-01
phase information cannot be accurately tracked. Based on analysis of the cause of double-frequency ripple when unbalance exists in main grid, a phase-locked loop (PLL) detection technique is proposed. Under the conditions of unsymmetrical system voltage, varying system frequency, single-phase system......It is a normal practice that the DC micro-grid is connected to AC main grid through Grid-connected Voltage Source Converter (G-VSC) for voltage support. Accurate control of DC micro-grid voltage is difficult for G-VSC under unbalanced grid condition as the fundamental positive-sequence component...
Hernandez, Gabriel D.
2016-01-01
Approved for public release; distribution is unlimited For an Energy Management System (EMS)-controlled microgrid that uses a single-phase voltage source inverter (VSI) configuration to supply power for AC loads from DC energy storage devices, the DC link connecting the VSI to the DC energy storage devices experiences a voltage ripple that is a second-order harmonic of the AC frequency. When the EMS has a battery bank as the only DC energy storage device, the DC link voltage ripple causes ...
Analysis of Capacitive Parasitism in PWM Inverter-Fed Motor
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
The effects of parasitic capacitance in induction motor system are unnoticed when it is fed from the AC line. but they are obvious when supplied directly from a PWM inverter. Consequently. many parasitic problems occur, such as motor-to-earth leakage current, bearing current, incoming line current distortion and uneven distribution of electrical stresses along the winding. On the ba sis of the uniform transmission line principle, a complete equivalent circuit of the PWM inverter-fed motor system is presented, based on which all the capacitive parasitic problems mentioned above are analyzed and simulated by means of PSPICE. All the results are consistent with the existing ones.
Small-signal, continuous, exact model of PWM voltage regulators
Burkhardt, W.; Maranesi, P.; Varoli, V.
1985-02-01
The small-signal time-continuous open-loop response of buck, boost, and buck-boost pulse-width-modulation (PWM) voltage regulators using MOSFET switches in their power stages is modeled, applying a time-domain sampling theorem (Woodward, 1953) to obtain the Fourier open-loop transfer function corresponding to the comb function describing the response at the chopping instants only. The results are presented graphically along with simplified circuit diagrams of the PWM devices, and the accuracy and computational efficiency of the analytical approach are indicated.
Low Loss Passive Snubber in Push-pull Voltage Source Inverter%一种用于推挽式电压型逆变器的低损耗无源吸收电路
Institute of Scientific and Technical Information of China (English)
伍家驹; 杉本英彦
2006-01-01
A low loss passive snubber is developed for the PWM push-pull Voltage Source Inverter (VSI). In order to avoid the superposition of the high frequency discharge energy on the output voltage, an independent discharge circuit is introduced to feed back part of the energy in the capacitor to DC source. Due to the voltage clamp on the capacitor, there is,for the doubled voltage of the push-pull circuit, no additional loss in the snubber. Details of design and a 200V DC input,30kW VSI application example are also presented.Experimental results show that the circuit topology is a good choice in low loss snubber design.%提出并实现了一种推挽式PWM电压型逆变器用无源吸收电路;设有独立的放电回路让缓冲电容器上的能量部分地回馈到直流电源中,高频放电能量不会叠加在输出电压上;缓冲电容器的电压被钳位,使得推挽电路特有的倍压不会在吸收电路上造成额外的损耗.给出吸收电路参数的设计准则和计算实例,在200VDC和30kW级的中压中功率逆变装置中发挥了推挽拓扑的优点.理论分析和实验验证了所提方法的有效性.
Three phase partitioning leads to subtle structural changes in proteins.
Rather, Gulam Mohmad; Gupta, Munishwar Nath
2013-09-01
Three phase partitioning consists of precipitation of proteins due to simultaneous presence of ammonium sulphate and t-butanol. The technique has been successfully used for purification and refolding of proteins. There are however indications that the structures of proteins subjected to three phase partitioning are different from native structure of proteins. Taking several proteins, the present work examines the structural changes in proteins by comparing their thermal stabilities, secondary structure contents, surface hydrophobicities, hydrodynamic radii and solubilities in the presence of ammonium sulphate. The results show that while the nature or extent of structural changes may vary, in all the cases the changes are rather subtle and not drastic in nature. Hence, the technique can be safely used for protein purification and refolding.
Accurate parameter estimation for unbalanced three-phase system.
Chen, Yuan; So, Hing Cheung
2014-01-01
Smart grid is an intelligent power generation and control console in modern electricity networks, where the unbalanced three-phase power system is the commonly used model. Here, parameter estimation for this system is addressed. After converting the three-phase waveforms into a pair of orthogonal signals via the α β-transformation, the nonlinear least squares (NLS) estimator is developed for accurately finding the frequency, phase, and voltage parameters. The estimator is realized by the Newton-Raphson scheme, whose global convergence is studied in this paper. Computer simulations show that the mean square error performance of NLS method can attain the Cramér-Rao lower bound. Moreover, our proposal provides more accurate frequency estimation when compared with the complex least mean square (CLMS) and augmented CLMS.
Enhanced control of DFIG-used back-to-back PWM VSC under unbalanced grid voltage conditions
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
This paper presents a unified positive- and negative-sequence dual-dq dynamic model of wind-turbine driven doublyfed induction generator (DFIG) under unbalanced grid voltage conditions. Strategies for enhanced control and operation of a DFIG-used back-to-back (BTB) PWM voltage source converter (VSC) are proposed. The modified control design for the grid-side converter in the stationary αβ frames diminishes the amplitude of DC-link voltage ripples of twice the grid frequency, and the two proposed control targets for the rotor-side converter are alternatively achieved, which, as a result, improve the fault-ride through (FRT) capability of the DFIG based wind power generation systems during unbalanced network supply. A complete unbalanced control scheme with both grid- and rotor-side converters included is designed. Finally, simulation was carried out on a 1.5 MW wind-turbine driven DFIG system and the validity of the developed unified model and the feasibility of the proposed control strategies are all confirmed by the simulated results.
Directory of Open Access Journals (Sweden)
Mohammad Sadegh Orfi Yegane
2017-02-01
Full Text Available This paper investigates multi-carrier PWM methods in multi-level inverters. Two new MCPWM methods are introduced. This study proposes a new optimized MCPWM method to improve the output voltage characteristics like THD and LOH. The proposed method is based on variable frequency with a specific range. It means each carrier wave has a determined frequency. It is calling Variable Frequency Triangular Carrier-PWM. MOPSO algorithm is used to optimize the answers. This work considers some different levels of inverters like five, seven and nine levels. The results are compared with SPWM method.
Institute of Scientific and Technical Information of China (English)
王宝忠; 孙健涛; 要丹
2011-01-01
Exactly detecting of rotor position was required during the control of brushless DC motor, and back EMF detecting method was a simple, effective way to detect the position-sensorless rotor position of brushless DC motor. A back EMF detecting method based on the H_PWM-L_PWM modulation model by analyzing the freewheeling condition of a non-conducted phase of this model was raised. This back EMF detecting method needed not to detect the center voltage of the three-phase winding, and gained a two times of the back EMF of a non-conducted phase. The simulation under MATLAB software environment and experimental results showed that this method had good performance in low speed control of brushless DC motor.%无刷电机的控制需要准确检测到转子的位置,反电动势法是检测无位置传感器无刷直流电机转子位置的一种简单、有效的方法.采用二相导通星形三相六状态的控制模式,通过分析在H_PWM-L PWM调制方式下不导通相的续流情况,提出了基于该调制方式的反电动势检测方法.该反电动势检测法不需要检测三相绕组中点电压,所获得的是不导通相的两倍的反电动势.MATLAB仿真和试验结果证明,该检测方法具有良好的低速控制性能.
Three-phase flow of submarine gas hydrate pipe transport
Institute of Scientific and Technical Information of China (English)
李立; 徐海良; 杨放琼
2015-01-01
In the hydraulic transporting process of cutter-suction mining natural gas hydrate, when the temperature−pressure equilibrium of gas hydrate is broken, gas hydrates dissociate into gas. As a result, solid−liquid two-phase flow (hydrate and water) transforms into gas−solid−liquid three-phase flow (methane, hydrate and water) inside the pipeline. The Euler model and CFD-PBM model were used to simulate gas−solid−liquid three-phase flow. Numerical simulation results show that the gas and solid phase gradually accumulate to the center of the pipe. Flow velocity decreases from center to boundary of the pipe along the radial direction. Comparison of numerical simulation results of two models reveals that the flow state simulated by CFD-PBM model is more uniform than that simulated by Euler model, and the main behavior of the bubble is small bubbles coalescence to large one. Comparison of numerical simulation and experimental investigation shows that the values of flow velocity and gas fraction in CFD-PBM model agree with experimental data better than those in Euler model. The proposed PBM model provides a more accurate and effective way to estimate three-phase flow state of transporting gas hydrate within the submarine pipeline.
Okedu, Kenneth Eloghene; Muyeen, S. M.; Takahashi, Rion; Tamura, Junji
Recent wind farm grid codes require wind generators to ride through voltage sags, which means that normal power production should be re-initiated once the nominal grid voltage is recovered. However, fixed speed wind turbine generator system using induction generator (IG) has the stability problem similar to the step-out phenomenon of a synchronous generator. On the other hand, doubly fed induction generator (DFIG) can control its real and reactive powers independently while being operated in variable speed mode. This paper proposes a new control strategy using DFIGs for stabilizing a wind farm composed of DFIGs and IGs, without incorporating additional FACTS devices. A new current controlled voltage source converter (CC-VSC) scheme is proposed to control the converters of DFIG and the performance is verified by comparing the results with those of voltage controlled voltage source converter (VC-VSC) scheme. Another salient feature of this study is to reduce the number of proportionate integral (PI) controllers used in the rotor side converter without degrading dynamic and transient performances. Moreover, DC-link protection scheme during grid fault can be omitted in the proposed scheme which reduces overall cost of the system. Extensive simulation analyses by using PSCAD/EMTDC are carried out to clarify the effectiveness of the proposed CC-VSC based control scheme of DFIGs.
Directory of Open Access Journals (Sweden)
P.Narasimhulu
2014-09-01
Full Text Available A reduced rating voltage-source converter with a zig-zag transformer as a distribution static compensator is proposed for power-quality improvement in the three-phase four-wire distribution system. The source voltages in the distribution systems are also experiencing power quality problems, such as harmonics, unbalance, flicker, sag, swell, etc. The distribution static compensator (DSTATCOM is proposed for compensating power quality problems in the current, and the dynamic voltage restorer (DVR is used for mitigating the power quality problems in the voltage. The zig-zag transformer is used for the neutral current compensation. Distribution systems are facing severe power-quality (PQ problems, such as poor voltage regulation, high reactive power and harmonics current burden, load unbalancing, excessive neutral current, etc. The zig-zag transformer is used for providing a path to the zero-sequence current. The DSTATCOM is used to improve the quality of power to the non linear loads. By using both zig-zag transformer and DSTATCOM in the distribution system the rating of the voltage source converter can be reduced. Hence it can be also called reduced rating device. The performance of the DSTATCOM is validated through extensive simulations using MATLAB software with its Simulink and power system block set toolboxes.
Studies in Three Phase Gas-Liquid Fluidised Systems
Awofisayo, Joyce Ololade
1992-01-01
Available from UMI in association with The British Library. The work is a logical continuation of research started at Aston some years ago when studies were conducted on fermentations in bubble columns. The present work highlights typical design and operating problems that could arise in such systems as waste water, chemical, biochemical and petroleum operations involving three-phase, gas-liquid -solid fluidisation; such systems are in increasing use. It is believed that this is one of few studies concerned with "true" three-phase, gas-liquid-solid fluidised systems, and that this work will contribute significantly to closing some of the gaps in knowledge in this area. The research work was experimentally based and involved studies of the hydrodynamic parameters, phase holdups (gas and solid), particle mixing and segregation, and phase flow dynamics (flow regime and circulation patterns). The studies have focused particularly on the solid behaviour and the influence of properties of solids present on the above parameters in three-phase, gas-liquid-solid fluidised systems containing single particle components and those containing binary and ternary mixtures of particles. All particles were near spherical in shape and two particle sizes and total concentration levels were used. Experiments were carried out in two- and three-dimensional bubble columns. Quantitative results are presented in graphical form and are supported by qualitative results from visual studies which are also shown as schematic diagrams and in photographic form. Gas and solid holdup results are compared for air-water containing single, binary and ternary component particle mixtures. It should be noted that the criteria for selection of the materials used are very important if true three-phase fluidisation is to be achieved: this is very evident when comparing the results with those in the literature. The fluid flow and circulation patterns observed were assessed for validation of the generally
PWM Regulation of Grid-Tied PV System on the Base of Photovoltaic-Fed Diode-Clamped Inverters
Directory of Open Access Journals (Sweden)
Oleschuk V.I.
2015-12-01
Full Text Available Investigation of grid-tied photovoltaic system on the base of two diode-clamped inverters, controlled by specific algorithms of pulse-width modulation (PWM, has been done. This system includes two strings of photovoltaic panels feeding two diode-clamped inverters. The outputs of inverters are connected with the corresponding windings on the primary side of three-phase transformer, connected with a grid. In order to reduce phase voltage distortion and to increase efficiency of operation of the system, special scheme of control and modulation of inverters has been used, providing minimization of common-mode voltages and voltage waveforms symmetries under different operating conditions. Detailed simulation of processes in this photovoltaic-fed power conversion system has been executed. The results of simulations verify good performance of photovoltaic system regulated in accordance with specific strategy of control and modulation.
A new Zero-Voltage-Transition PWM switching cell
Energy Technology Data Exchange (ETDEWEB)
Grigore, V. [Electronics and Telecommunications Faculty `Politebuica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics
1997-12-31
In this paper a new Zero-Voltage-Transition (ZVT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus an auxiliary circuit (consisting of one active switch and some reactive components). The auxiliary circuit is inactive during the ON and OFF intervals of the switches in the normal PWM switch. However, the transitions between the two states are controlled by the auxiliary circuit. Prior to turn-on, the voltage across the active switch in the PWM cell is forced to zero, thus the turn-on losses of the active switch are practically eliminated. At turn-off the auxiliary circuit behaves like a non-dissipative passive snubber reducing the turn-off losses to a great extent. Zero-Voltage-Transition switching technique almost eliminates switching losses. The active switch operates under ZVT conditions, the passive switch (diode) has a controlled reverse recovery, and the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 6 refs.
A new Zero-Current-Transition PWM switching cell
Energy Technology Data Exchange (ETDEWEB)
Grigore, V. [Electronics and Telecommunications Faculty, `Politechnica` University Bucharest (Romania); Kyyrae, J. [Helsinki University of Technology, Otaniemi (Finland): Institute of Intelligent Power Electronics
1997-12-31
In this paper a new Zero-Current-Transition (ZCT) PWM switching cell is presented. The proposed switching cell is composed of the normal hard-switched PWM cell (consisting of one active switch and one passive switch), plus as auxiliary circuit. The auxiliary circuit is inactive during the ON ad OFF intervals of the switches in the normal PWM switch. The transitions between the two states are controlled by the auxiliary circuit. Prior to turn-off, the current through the active switch in the PWM cell is forced to zero, thus the turn-off losses of the active switch are practically eliminated. At turn-on the auxiliary circuit slows down the growing rate of the current through the main switch. Thus, turn-on losses are also very much reduced. The active switch operates under ZCT conditions, the passive switch (diode) has a controlled reverse recovery, while the switch in the auxiliary circuit operates under Zero-Current-Switching (ZCS) conditions. (orig.) 3 refs.
Spread Spectrum Modulation by Using Asymmetric-Carrier Random PWM
DEFF Research Database (Denmark)
Mathe, Laszlo; Lungeanu, Florin; Sera, Dezso;
2012-01-01
This paper presents a new fixed carrier frequency random PWM method, where a new type of carrier wave is proposed for modulation. Based on simulations and experimental measurements, it is shown that the spread effect of the discrete components from the motor current spectra and acoustic spectra i...
Simple PWM modulator topology with excellent dynamic behavior
DEFF Research Database (Denmark)
Poulsen, Søren; Andersen, Michael Andreas E.
2004-01-01
This paper proposes a new PWM modulator topology. The modulator is used in switch mode audio power amplifiers, but the topology can be used in a wide range of applications. Due to excellent transient behavior, the modulator is very suited for VRMs or other types of DC-DC or DC-AC applications....
单周期控制三相VIENNA整流器%Three-Phase VIENNA Rectifier by One-Cycle Control
Institute of Scientific and Technical Information of China (English)
冯鑫振; 高捷
2012-01-01
The attention devoted to reducing grid harmonic pollution is increasing. Power tactor correction （PFC） is an effective method to reduce harmonic current in power grid. This paper researches a three-phase VIENNA PWM rectifier based on one-cycle control（OCC）. The control rules of a three-phase VIENNA rectifier by one-cycle control are deduced. Compared with other control program does not require multipliers, without the power supply voltage detection, so this control logic is relatively simple and can be achieved with congtant switching frequency, the unit power factor correction and low current distortion. The simulation results verify the theoretical analysis.%电网谐波污染已经引起世界各国的高度重视,功率因数校正（PFC）是治理谐波的一种有效方法。文章对基于单周期控制的三相VIENNA整流器进行了研究,推导了单周期控制三相VIENNA整流器的控制规律,与其它控制方案相比不需要乘法器,不需对电源电压进行检测,控制逻辑比较简单并且以恒定开关频率工作,能够实现单位功率因数校正和低电流畸变。仿真结果验证了理论分析的正确性。
A Single Phase to Three Phase PFC Half-Bridge Converter Using BLDC Drive with SPWM Technique.
Directory of Open Access Journals (Sweden)
Srinu Duvvada
2014-07-01
Full Text Available In this paper, a buck half-bridge DC-DC converter is used as a single-stage power factor correction (PFC converter for feeding a voltage source inverter (VSI based permanent magnet brushless DC motor (BLDC drive. The front end of this PFC converter is a diode bridge rectifier (DBR fed from single-phase AC mains. The BLDC is used to drive a compressor load of an air conditioner through a three-phase VSI fed from a controlled DC link voltage. The speed of the compressor is controlled to achieve energy conservation using a concept of the voltage control at DC link proportional to the desired speed of the BLDC. Therefore the VSI is operated only as an electronic commutator of the BLDC. The stator current of the BLDC during step change of reference speed is controlled by a rate limiter for the reference voltage at DC link. The proposed BLDC drive with voltage control based PFC converter is designed, modeled and its performance is simulated in Matlab-Simulink environment for an air conditioner compressor driven through a 1.5 kW, 1500 rpm BLDC motor. The evaluation results of the proposed speed control scheme are presented to demonstrate an improved efficiency of the proposed drive system with PFC feature in wide range of the speed and an input AC voltage.
Three-Phase High-Power and Zero-Current-Switching OBC for Plug-In Electric Vehicles
Directory of Open Access Journals (Sweden)
Cheng-Shan Wang
2015-06-01
Full Text Available In this paper, an interleaved high-power zero-current-switching (ZCS onboard charger (OBC based on the three-phase single-switch buck rectifier is proposed for application to plug-in electric vehicles (EVs. The multi-resonant structure is used to achieve high efficiency and high power density, which are necessary to reduce the volume and weight of the OBC. This study focuses on the border conditions of ZCS converting with a battery load, which means the variation ranges of the output voltage and current are very large. Furthermore, a novel hybrid control method combining pulse frequency modulation (PFM and pulse width modulation (PWM together is presented to ensure a driving frequency higher than 10 kHz, and this will reduce the unexpected inner resonant power flow and decrease the total harmonic distortion (THD of the input current under a light load at the end of the charging process. Finally, a prototype is established, and experiments are carried out. According to the experimental results, the conversion efficiency is higher than 93.5%, the THD about 4.3% and power factor (PF 0.98 under the maximum power output condition. Besides, a three-stage charging process is also carried out the experimental platform.
Institute of Scientific and Technical Information of China (English)
Mary Kaye; Chris Diduch; Qing-rong ZENG; Idris Gadoura; Liu-chen ZHANG
2011-01-01
Voltage space vector pulse-width modulation(SVPWM) has been widely applied to control current in threephase vohage source inverters (VSI).However,as a voltage type modulator,SVPWM has certain drawbacks compared with current type modulators for grid-connected applications.For a grid-connected VSI,the performance of existing current controllers based on SVPWM is compromised by grid harmonics,control delay and system nonlinearities such as switching dead time.Moreover,unlike current type PWM,SVPWM does not inherently have over-current protection.A novel SVPWM-based current controller is proposed for three-phase grid-connected VSIs for small wind turbine applications.To overcome the drawbacks of SVPWM,a grid harmonic compensation method is proposed along with compensation for control delays.Both simulation and experimental results have established excellent steady-state response and fast dynamic response of the current controller.In addition,the DSP-based control system has both improved real-time control performance and fast response for over-current protection.
Research of VIENNA-type Three-phase There-level PWM Rectifier%VIENNA型三相三电平PWM整流器研究
Institute of Scientific and Technical Information of China (English)
周奖; 陆翔; 权运良
2013-01-01
分析了VIENNA型三相三电平PWM整流器的拓扑及其数学模型,以及三电平变换器的状态空间矢量调制技术(SVPWM).提出了基于PI控制的双闭环的控制策略(即电压外环、电流内环),并引入中点电位因子r对中点电压进行平衡控制.为了验证所提控制策略的可行性,搭建了VIENNA型三相三电平PWM整流器的仿真平台以及1.6 kW的实验样机进行仿真与实验研究.仿真及实验结果表明,所提出的调制方法及控制策略是可行的.该整流器具有控制简单、易于数字化实现、在稳态条件下谐波畸变率小于3％、功率因数接近1等特点.
DEFF Research Database (Denmark)
Han, Yang; Luo, Mingyu; Chen, Changqing;
2016-01-01
The moving average filter (MAF) is widely utilized to improve the disturbance rejection capability of the phase-locked loops (PLLs), which is of vital significance for the grid-integration and stable operation of power electronic converters to the electric power systems. However, the open-loop...... among the advanced MAF-based PLL algorithms is presented, which includes HPLL, MPLC-PLL, QT1-PLL, and DMAF-PLL. Various grid voltage disturbance scenarios, such as grid voltage sag, voltage flicker, and harmonics distortion, phase-angle and frequency jumps, DC offsets and noise, are considered...
Three-Phase PLLs: A Review of Recent Advances
DEFF Research Database (Denmark)
Golestan, Saeed; Guerrero, Josep M.; Vasquez, Juan C.
2017-01-01
A phase-locked loop (PLL) is a nonlinear negativefeedback control system that synchronizes its output in frequency as well as in phase with its input. PLLs are now widely used for the synchronization of power electronics-based converters and also for monitoring and control purposes in different e...... engineering fields. In recent years, there have been many attempts to design more advanced PLLs for three-phase applications. The aim of this paper is to provide overviews of these attempts, which can be very useful for engineers and academic researchers....
Additional losses in three-phase transformer cores
Valković, Z.
1984-02-01
The influences of T-joint design and of the holes in yoke lamination on the magnetic properties have been investigated on scale models of three-phase three-limbed transformer core. Four variants of V-45° T-joint have been compared, and it has been found that they have virtually equal power losses, while the differences in magnetizing currents amount up to 60%. The variations of losses and magnetizing currents with hole diameter and flux density in the core are given. In distribution transformers of usual dimensions, a 2-4% increase of power losses due to holes in the yoke has been estimated.
A DSP controlled one-to-three phase matrix converter
Energy Technology Data Exchange (ETDEWEB)
Dubovsky, J.; Dobrucly, B; Tabacek, R.; Havrila, R. [Department of Electric Traction and Energetics Faculty of Electrical Engineering, University of Zilina (Slovakia)
1997-12-31
This paper deals with the theoretical analysis computer simulation and experimental results of IM fed by a one-to-three phase matrix converter which offers a unique solution for single phase electric traction applications. The proposed drive in comparison with currently used conventional drives reduces the number of power switching elements of the converter, which increases drives dependability and brings lower investment in power electronics used in drive. Further advantage is that the converter is controlled with nearly unity power factor which cuts down the operational expenses and offers higher overall performance of the drive. (orig.) 6 refs.
Evaluation of Three-Phase Transformerless Photovoltaic Inverter Topologies
DEFF Research Database (Denmark)
Kerekes, Tamas; Liserre, Marco; Teodorescu, Remus
2009-01-01
This paper analyzes and compares three transformerless photovoltaic inverter topologies for three-phase grid connection with the main focus on the safety issues that result from the lack of galvanic isolation. A common-mode model, valid at frequencies lower than 50 kHz, is adopted to study...... the leakage current paths. The model is validated by both simulation and experimental results. These will be used to compare the selected topologies, and to explain the influence of system unbalance and the neutral conductor inductance on the leakage current. It will be demonstrated that the later has...
Program for three-phase power transformer design
Directory of Open Access Journals (Sweden)
Olivian Chiver
2011-12-01
Full Text Available This paper presents a program developed for designing three-phase power transformers used in power systems. The program was developed in Visual Basic because this programming language allows us to realize a friendly and suggestive interface with minimum effort. The second reason, which is the most important, is to use Visual Basic, because this language is recognized by the used finite elements analysis (FEA software, MagNet produced by Infolytica. This software package is designed for calculation of the magnetic field of electromagnetic devices and machines. The 3D components of the numerical model are carried out using CATIA program, automatically, based on the calculated main geometric data.
Three-Phase Load Flow for Unbalanced Systems.
Chang, Yih-Ping
Traditionally, transmission systems are assumed to be balanced in power system analysis. A single phase positive sequence circuit is used in transmission system load flow analysis to simplify the study. However, when untransposed transmission lines are used in a power system due to economic considerations, space limitation; or when large unbalanced load is on the system; or when an unbalance contingency occurs on the system, this assumption may not hold true. The unbalance condition in some isolated systems are so precarious that disaster can result. One such incident occurred on a generator unit of the third nuclear power plant of Taipower in 1985. In that particular case, the turbine blades were broken and a spark ignited the liquid hydrogen when the blade vibration resonated with the 120.5 Hz rotor current. One cause of this rotor current generation is system unbalance. The unbalanced three-phase load flow program is needed in today's power system analysis. An advanced three-phase unbalanced transmission load flow program, capable of locating the unbalanced problem of large electric network systems, was proposed to be developed and tested in this research. Features of this program include simultaneous power flow of multiple voltage levels on an individual phase basis; PV bus generator, cogenerator, transformer simulation, and load modeling. It is found that delta-grounded wye step-up transformer reduces the convergence speed greatly. When too many delta-grounded wye step-up transformers exist in a large scale system and a quick approximate result of the unbalance conditions is needed, these step-up transformers can be substituted by grounded-wye to grounded-wye type transformers. This is tested on a Taipower system case which included 345KV, 161KV and 69KV feeders, network transformers, 34 PV bus generators and 188 three-phase buses. Impending unbalance problems in Taipower system were located. When not too many delta-grounded wye type transformers are in the
Energy Technology Data Exchange (ETDEWEB)
Svensson, Jan [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Electric Power Engineering
1996-12-01
In this paper the hybrid wind farm connected to a weak grid is investigated. By combining different electrical wind power plant systems a cost-efficient solution is obtained. The point of common connection voltage level can be controlled by injecting reactive power from a phase-compensating capacitor battery and a voltage source inverter (VSI). If the short-circuit impedance ratio is lower than 1, the demanded reactive power injection to keep the voltage at nominal level is unrealistic. For short-circuit impedance ratios of 2 or higher the demanded reactive power level is acceptable. When using both induction generators and thyristor inverters the reactive power injector VSI size should be about 0.2 pu. If the hybrid farm consists of THYs, IGs and VSIs and the active power is equally shared between the systems, the VSI had to be scaled up by 5% to handle both active and reactive power. 7 refs, 10 figs, 2 tabs
Sinthusonthishat, S.; Kinnares, V.
This paper proposes a new modulation scheme providing unbalanced output terminal voltages of a standard three-leg voltage source inverter (VSI) for unsymmetrical type two-phase induction motors. This strategy allows a control method of the output voltages with typically constant V/Hz for a main winding and with voltage boost to compensate magnitude of current for an auxiliary winding. Harmonic voltage characteristics and the motor performance are investigated under a wide range of operating conditions. Practical verification is presented to confirm correctness and capabilities of the proposed technique. All results are compared to those of a conventional two-leg half bridge topology. The results show that the simulation results well agree with the experimental ones, and also the proposed scheme is superior to the conventional drive.
Inverter Output Filter Effect on PWM Motor Drives of a Flywheel Energy Storage System
Santiago, Walter
2004-01-01
NASA Glenn Research Center (GRC) has been involved in the research and development of high speed flywheel systems for small satellite energy storage and attitude control applications. One research and development area has been the minimization of the switching noise produced by the pulsed width modulated (PWM) inverter that drives the flywheel permanent magnet motor/generator (PM M/G). This noise can interfere with the flywheel M/G hardware and the system avionics hampering the full speed performance of the flywheel system. One way to attenuate the inverter switching noise is by placing an AC filter at the three phase output terminals of the inverter with the filter neutral point connected to the DC link (DC bus) midpoint capacitors. The main benefit of using an AC filter in this fashion is the significant reduction of the inverter s high dv/dt switching and its harmonics components. Additionally, common mode (CM) and differential mode (DM) voltages caused by the inverter s high dv/dt switching are also reduced. Several topologies of AC filters have been implemented and compared. One AC filter topology consists of a two-stage R-L-C low pass filter. The other topology consists of the same two-stage R-L-C low pass filter with a series connected trap filter (an inductor and capacitor connected in parallel). This paper presents the analysis, design and experimental results of these AC filter topologies and the comparison between the no filter case and conventional AC filter.
Hydrodynamic Behavior of Three-Phase Airlift Loop Slurry Reactor
Institute of Scientific and Technical Information of China (English)
任飞; 王金福; 王铁峰; 金涌
2002-01-01
A novel fiber optic probe system and a set of commercial ultrasonic Doppler velocimeters have been used to study the hydrodynamic behavior of a three-phase airlift loop (TPAL) slurry reactor. Experiments have been carried out in a loop reactor with 100 mm inner diameter and 2.5 m height, in which air, tap water and silica gel particles are used as the gas, liquid and solid phase, respectively. The radial profile of gas holdup, bubble size, bubble rising velocity, liquid circulating velocity, and the influence of the main operating conditions such as superficial gas velocity and solids concentration have been studied experimentally in the TPAL slurry reactor. The experimental results show that the bubble characteristics are different in various flow regimes and the radial profiles of some hydrodynamic parameters in the TPAL slurry reactor are more uniform than those in traditional three-phase reactors. The distribution of the bubble size and bubble rising velocity can be described by a lognormal function. The influence of superficial gas velocity on the hydrodynamic parameters is more remarkable than that of the solids concentration.
A novel three-phase model of brain tissue microstructure.
Directory of Open Access Journals (Sweden)
Jana L Gevertz
Full Text Available We propose a novel biologically constrained three-phase model of the brain microstructure. Designing a realistic model is tantamount to a packing problem, and for this reason, a number of techniques from the theory of random heterogeneous materials can be brought to bear on this problem. Our analysis strongly suggests that previously developed two-phase models in which cells are packed in the extracellular space are insufficient representations of the brain microstructure. These models either do not preserve realistic geometric and topological features of brain tissue or preserve these properties while overestimating the brain's effective diffusivity, an average measure of the underlying microstructure. In light of the highly connected nature of three-dimensional space, which limits the minimum diffusivity of biologically constrained two-phase models, we explore the previously proposed hypothesis that the extracellular matrix is an important factor that contributes to the diffusivity of brain tissue. Using accurate first-passage-time techniques, we support this hypothesis by showing that the incorporation of the extracellular matrix as the third phase of a biologically constrained model gives the reduction in the diffusion coefficient necessary for the three-phase model to be a valid representation of the brain microstructure.
DEFF Research Database (Denmark)
Teodorescu, Remus; Blaabjerg, Frede
2004-01-01
This paper is describing the recently introduced proportional-resonant (PR) controllers and their suitability for grid-connected converters current control. It is shown that the known shortcomings associated with PI controllers like steady - state error for single-phase converters and the need...... of decoupling for three-phase converters can be alleviated. Additionally, selective harmonic compensation is also possible with PR controllers. Suggested control-diagrams for three-phase grid converters and active filters are also presented. A practical application of PR current control for a photovoltaic (PV...
The Analysis and Compensation of Output Error for Voltage Source PWM Inverter%电压型PWM逆变器输出误差分析及其补偿
Institute of Scientific and Technical Information of China (English)
陈硕; 薛昭武
2001-01-01
由于死区时间和电力电子器件IGBT非理想特性的影响，PWM逆变器存在输出误差，使得众多的调速方案在低速运行时性能不佳或无法实现调速。本文详细分析死区时间和IGBT非理想特性对输出电压的影响，提出测量IGBT非理想特性方法和输出误差补偿法，并通过实验验证了误差补偿法的有效性。%Because a tWM inverter has an output error due to the dead time and the non-tdeal characteristic of IGBT, a number of variable speed schemes cannot obtain a good performance or operate at low speed. This paper analyzes the influence of the dead time and the non-ideal characteristic on the output voltage in detail, and proposes a measurement of IGBT and a compensating algorithm for the inverter. The validity of the proposed method has been verified by experimentation.
Dynamic Simulation of Induction Motor Fed by SVPWM Voltage Source Inverter%SVPWM电压源逆变器供电异步电动机的动态仿真
Institute of Scientific and Technical Information of China (English)
张贻旭; 谢卫; 屈鲁; 卢颖娟
2012-01-01
The dynamic model of three-phase induction motor is established in the d-q coordinate. Sinusoidal pulse width modulation （SPWM） technique and space vector pulse width modulation （SVPWM） technique which used to control induction motor are introduced. Dynamic simulation model of three - phase induction motor fed by SPWM and SVPWM voltage source inverter are established respectively, and the simulation results under these two control techniques are comparatively analyzed. The simulation results demonstrate that SVPWM induction motor drive system can start faster, the torque ripple is smaller and the stator current harmonics is smaller compared with SPWM control. The system has good steady and dynamic performance.%建立了三相异步电动机在d-q坐标系下的动态数学模型,并介绍了控制异步电动机运行的两种控制技术：正弦波脉宽调制（SPWM）技术和空间电压矢量脉宽调制（SVPWM）技术。在Matlab/Simulink环境下,分别建立SPWM和SVPWM电压源型逆变器供电的三相异步电动机的动态仿真模型,比较分析了在这两种控制方式下的仿真结果。结果表明,较之SPWM控制方式,SVPWM的异步电动机变频调速系统启动快,转矩脉动小,定子电流谐波小,具有较好的动态性能和稳态性能。
On the Well-posedness of the PWM Control System
Institute of Scientific and Technical Information of China (English)
FAN Qi-fu; SHI Song-jiao
2006-01-01
One of the basic issues in the study of hybrid systems is the well-posedness (existence and uniqueness of solutions) problem of discontinuous dynamical systems.This paper addresses this problem for a class of piecewise affine discontinuous systems with affine inequalities such as systems with pulse-width modulator under the definition lexicographic inequalities and the smooth continuation property of solutions.Furthermore,it is clear that when carrier signal h(t)=0,closed-loop pulse-width modulation (PWM) DC-DC converters are not well posed,and when some condition is satisfied,the closed-loop PWM DC-DC converters with a P controller are well posed.
OFDM-PWM scheme for visible light communications
Zhang, Tian; Ghassemlooy, Zabih; Rajbhandari, Sujan; Popoola, Wasiu O.; Guo, Shuxu
2017-02-01
In this paper, we propose an improved hybrid optical orthogonal frequency division multiplexing (O-OFDM) and pulse-width modulation (PWM) scheme for visible light communications. In this scheme, a bipolar O-OFDM signal is converted into a PWM format where the leading and trailing edges convey the frame synchronization and modulated information, respectively. The proposed scheme is insensitive to the non-linearity of the light emitting diode (LED) as LEDs are switched 'on' and 'off' between two points. Therefore, the tight requirement on the high peak-to-average-power-ratio (PAPR) in O-OFDM is no longer a major issue. The simulation and experimental results demonstrate that the proposed scheme offers an improved bit error rate performance compared to the traditional asymmetrically clipped O-OFDM (ACO-OFDM).
Intelligent System for Diagnosis of a Three-Phase Separator
Directory of Open Access Journals (Sweden)
Irina Ioniţă
2016-03-01
Full Text Available Intelligent systems for diagnosis have been used in a variety of domains: financial evaluation, credit scoring problem, identification of software and hardware problems of mechanical and electronic equipment, medical diagnosis, fault detection in gas-oil production plants etc. The goal of diagnosis systems is to classify the observed symptoms as being caused by some diagnosis class while advising systems perform such a classification and offer corrective remedies (recommendations. The current paper discuss the opportunity to combine more intelligent techniques and methodologies (intelligent agents, data mining and expert systems to increase the accuracy of results obtained from the diagnosis of a three-phase separator. The results indicate that the diagnosis hybrid system benefits from the advantages of each module component: intelligent agent module, data mining module and expert system module.
Realization of station for testing asynchronous three-phase motors
Wróbel, A.; Surma, W.
2016-08-01
Nowadays, you cannot imagine the construction and operation of machines without the use of electric motors [13-15]. The proposed position is designed to allow testing of asynchronous three-phase motors. The position consists of a tested engine and the engine running as a load, both engines combined with a mechanical clutch [2]. The value of the load is recorded by measuring shaft created with Strain Gauge Bridge. This concept will allow to study the basic parameters of the engines, visualization motor parameters both vector and scalar controlled, during varying load drive system. In addition, registration during the variable physical parameters of the working electric motor, controlled by a frequency converter or controlled by a contactor will be possible. Position is designed as a teaching and research position to characterize the engines. It will be also possible selection of inverter parameters.
Advanced nonlinear control of three phase series active power filter
Directory of Open Access Journals (Sweden)
Abouelmahjoub Y.
2014-01-01
Full Text Available The problem of controlling three-phase series active power filter (TPSAPF is addressed in this paper in presence of the perturbations in the voltages of the electrical supply network. The control objective of the TPSAPF is twofold: (i compensation of all voltage perturbations (voltage harmonics, voltage unbalance and voltage sags, (ii regulation of the DC bus voltage of the inverter. A controller formed by two nonlinear regulators is designed, using the Backstepping technique, to provide the above compensation. The regulation of the DC bus voltage of the inverter is ensured by the use of a diode bridge rectifier which its output is in parallel with the DC bus capacitor. The Analysis of controller performances is illustrated by numerical simulation in Matlab/Simulink environment.
Three-Phase Unbalanced Load Flow Tool for Distribution Networks
DEFF Research Database (Denmark)
Demirok, Erhan; Kjær, Søren Bækhøj; Sera, Dezso;
2012-01-01
This work develops a three-phase unbalanced load flow tool tailored for radial distribution networks based on Matlab®. The tool can be used to assess steady-state voltage variations, thermal limits of grid components and power losses in radial MV-LV networks with photovoltaic (PV) generators where...... most of the systems are single phase. New ancillary service such as static reactive power support by PV inverters can be also merged together with the load flow solution tool and thus, the impact of the various reactive power control strategies on the steady-state grid operation can be simply...... investigated. Performance of the load flow solution tool in the sense of resulting bus voltage magnitudes is compared and validated with IEEE 13-bus test feeder....
Optimal anisotropic three-phase conducting composites: Plane problem
Cherkaev, Andrej
2010-01-01
The paper establishes tight lower bound for effective conductivity tensor $K_*$ of two-dimensional three-phase conducting anisotropic composites and defines optimal microstructures. It is assumed that three materials are mixed with fixed volume fractions and that the conductivity of one of the materials is infinite. The bound expands the Hashin-Shtrikman and Translation bounds to multiphase structures, it is derived using the technique of {\\em localized polyconvexity} that is a combination of Translation method and additional inequalities on the fields in the materials; similar technique was used by Nesi (1995) and Cherkaev (2009) for isotropic multiphase composites. This paper expands the bounds to the anisotropic composites. The lower bound of conductivity (G-closure) is a piece-wise analytic function of eigenvalues of $K_*$, that depends only on conductivities of components and their volume fractions. Also, we find optimal microstructures that realize the bounds, developing the technique suggested earlier ...
Mass transfer in three-phase fluidized beds
Energy Technology Data Exchange (ETDEWEB)
Wu, B.W.; Cheng, Y.L.; Perini, J.R.; Roux-Buisson, J.L.
1978-04-26
The effects of superficial liquid and gas velocity, particle diameter, liquid viscosity, and column diameter on liquid dispersion (E/sub L) and mass transfer (K/sub L/a) in three-phase fluidized beds were investigated using a water--glycerol/oxygen--nitrogen (or oxygen--argon)/glass-bead system. Overall mass transfer coefficients were calculated based on plug flow, dispersed plug flow, and continuously stirred tank models. k/sub L/a was found to increase with gas velocity and particle diameter, but no correlation of K/sub L/a with liquid velocity was observed. At low liquid velocities, K/sub L/a was lower for the more viscous liquid; the reverse was true at high liquid flow rates. E/sub L/ increased rapidly for liquid flow rates at two to three times the minimum fluidization velocity.
Transient regimes of the three-phase power transformers
Directory of Open Access Journals (Sweden)
Olivian Chiver
2015-12-01
Full Text Available The transient regimes of a three-phase power transformer will be studied in this paper. The transient currents in the windings will be determined both analytically and by finite elements method (FEM. The no load and short circuit regimes will be considered. The current dependence of the instantaneous phase voltage and of the initial current value will be highlighted, by FEM. In order to determine analytically the transient currents, for inductances the analytical and FEM values will be used. The inductances are determined with FEM through the simulation of experimental tests. With FEM, the transient currents will be determined using transient analysis. Finally, the FEM and analytical results will be compared and discussed.
One dimensional speckle fields generated by three phase level diffusers
Cabezas, L.; Amaya, D.; Bolognini, N.; Lencina, A.
2015-02-01
Speckle patterns have usually been obtained by using ground glass as random diffusers. Liquid-crystal spatial light modulators have opened the possibility of engineering tailored speckle fields obtained from designed diffusers. In this work, one-dimensional Gaussian speckle fields with fully controllable features are generated. By employing a low-cost liquid-crystal spatial light modulator, one-dimensional three phase level diffusers are implemented. These diffusers make it possible to control average intensity distribution and statistical independence among the generated patterns. The average speckle size is governed by an external slit pupil. A theoretical model to describe the generated speckle patterns is developed. Experimental and theoretical results confirming the generation of one-dimensional speckle fields are presented. Some possible applications of these speckles, such as atom trapping and super-resolution imaging, are briefly envisaged.
Comparative assessment of three-phase oil relative permeability models
Ranaee, Ehsan; Riva, Monica; Porta, Giovanni M.; Guadagnini, Alberto
2016-07-01
We assess the ability of 11 models to reproduce three-phase oil relative permeability (kro) laboratory data obtained in a water-wet sandstone sample. We do so by considering model performance when (i) solely two-phase data are employed to render predictions of kro and (ii) two and three-phase data are jointly used for model calibration. In the latter case, a Maximum Likelihood (ML) approach is used to estimate model parameters. The tested models are selected among (i) classical models routinely employed in practical applications and implemented in commercial reservoir software and (ii) relatively recent models which are considered to allow overcoming some drawbacks of the classical formulations. Among others, the latter set of models includes the formulation recently proposed by Ranaee et al., which has been shown to embed the critical effects of hysteresis, including the reproduction of oil remobilization induced by gas injection in water-wet media. We employ formal model discrimination criteria to rank models according to their skill to reproduce the observed data and use ML Bayesian model averaging to provide model-averaged estimates (and associated uncertainty bounds) of kro by taking advantage of the diverse interpretive abilities of all models analyzed. The occurrence of elliptic regions is also analyzed for selected models in the framework of the classical fractional flow theory of displacement. Our study confirms that model outcomes based on channel flow theory and classical saturation-weighted interpolation models do not generally yield accurate reproduction of kro data, especially in the regime associated with low oil saturations, where water alternating gas injection (WAG) techniques are usually employed for enhanced oil recovery. This negative feature is not observed in the model of Ranaee et al. (2015) due to its ability to embed key effects of pore-scale phase distributions, such as hysteresis effects and cycle dependency, for modeling kro observed
Directory of Open Access Journals (Sweden)
Vargese Jegathesan
2008-01-01
Full Text Available This paper presents an efficient and reliable Genetic Algorithm-based solution for Specific Harmonic Elimination (SHE switching pattern. This method eliminates considerable amount of lower order line voltage harmonics in Pulse Width Modulation (PWM inverter. The determination of pulse pattern for the elimination of some lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Genetic Algorithm is used to solve nonlinear transcendental equations for PWM-SHE. In this proposed method, harmonics up to 17th are eliminated using Genetic Algorithm without using Dual transformer. Simulations using Matlab 7.0 and PSIM 6.1 are carried out so as to validate the solution.
Analysis of Dither in PWM Control on Electro-hydraulic Proportional Valve
Directory of Open Access Journals (Sweden)
Guoping LIU
2013-11-01
Full Text Available Plus with modulation (PWM is widely used in proporational control systems for it is efficient, flexible and anti-interference. Due to the friction and hysteresis of electromagnet, hysteresis exists when hydraulic valve in steady-state, and hysteresis influences the dynamic characteristics of the valve seriously,the hysteresis can be improved by superimposing dithers with certain frequency and amplitude to the valve coil. Aiming at the character of anti-unloading power driver circuit ,this paper analyzed the parasitic dither which exists in ±24V PWM control，besides，the experiment shows that in a high frequency PWM, dither with independent frequency and amplitude can be generated by changing the frequency of the PWM, in this way, the dithers and average current of coil can be adjusted separately by changing PWM frequency and PWM duty cycle.
Power electronic converters PWM strategies and current control techniques
Monmasson, Eric
2013-01-01
A voltage converter changes the voltage of an electrical power source and is usually combined with other components to create a power supply. This title is devoted to the control of static converters, which deals with pulse-width modulation (PWM) techniques, and also discusses methods for current control. Various application cases are treated. The book is ideal for professionals in power engineering, power electronics, and electric drives industries, as well as practicing engineers, university professors, postdoctoral fellows, and graduate students.
Dynamics of IGBT based PWM Converter A Case Study
Directory of Open Access Journals (Sweden)
Vijay Shukla
2012-04-01
Full Text Available Optimizing the efficiency and dynamics of power converters is a critical tradeoff in power electronics. The increase of switching frequency can improve the dynamics of power converters, but theefficiency may be degraded as well as the switching losses. As power semiconductor devices like diodes, MOSFETS, IGBTs, Thyristors, BJTs have their own characterstics and dynamic responses. It is desired toanalyze and observe the dynamics of different semiconductor devices before they actually employed in the model. Inclusion of different PWM techniques help in the removal of power line interferences like harmonic losses, unwanted ripples, chopped frequencies, spikes. In this paper, we have studied and analyzed the dynamics of IGBT based PWM converter with subjected to different conditions like transient state, steady state feeding the RLC load. Snubber circuits are used to reduce the switching losses. The IGBT based PWM converter reflects the better dynamics with improved efficiency and reduced harmonics as compared to some other power semiconductor devices when FFT is performed and subjected to standard parameterized RLC load understeady state and transient analysis.
Analysis and Simulation of a High Performance Quasi Resonant PWM Inverter for Solar Power Generation
Institute of Scientific and Technical Information of China (English)
Yun-Parn Lee; Yu-Huang Lin; Yu-Lun Lin
2016-01-01
A quasi resonant pulse width modulation (PWM) inverter is used in a solar power system to convert the solar panel and battery charger’s direct current (DC) output to alternating current (AC). Although much has been published about DC to AC PWM inverters, none of the previous work has shown modeling and simulation results for DC to AC inverters. In this study, we suggest a new topology for a quasi resonant PWM inverter. Experimental results are also presented.
Controlling DC Motor using Microcontroller (PIC16F72) with PWM
Shruti Shrivastava, Jageshwar Rawat, Amit Agrawal
2012-01-01
Motion control plays a vital role in industrial atomization. Different types of motors AC, DC, SERVO or stepper are used depending upon the application; of these DC motors are widely used because of easier controlling. Among the different control methods for DC motor armature voltage control method using pulse width modulation (PWM) is best one. We can realize the PWM using H-bridge built with IGBT switches or transistors. To generate PWM signals we use PIC16F7...
Synthesis of Voltages of Multiple Uniform PWM, Generated by Trapezoidal and Sinusoidal Functions
Directory of Open Access Journals (Sweden)
A. Ctryzhniou
2013-01-01
Full Text Available The problem of synthesis and qualitative estimation of the harmonic composition of voltages of multiple uniform PWM pulses generated by trapezoidal and sinusoidal functions is considered. Analytical expressions for PWM pulses parameters ai and ti have been received and they can be used for program-based generation of multiple uniform PWM, determination of n-harmonic magnitude in pulse-width regulation and AC motor operation simulation.
High-Frequency Link Inverter for Fuel Cells Based on Multiple-Carrier PWM （to continue）
Institute of Scientific and Technical Information of China (English)
无
2004-01-01
C. Operation of a PWM Cycloconverter The concepts in Section Ⅱ-B, present a progression of solutions to known design difficulties. To incorporate these benefits and eliminate the redundant conversion step shown in Fig. 6, we propose the PWM cycloconverter shown in Fig. 7. It will be shown in Section Ⅲ. that the conventional PWM inverter can be unified through a multiple-carrier PWM framework. The control concept introduced is extended to demonstrate that multiple-carrier PWM methods lead to HF link inverters that are nearly as simple to control as conventional PWM inverters.
Dimensional similitude and the hydrodynamics of three- phase fluidized beds
Safoniuk, Michael
It is proposed that scaling of three-phase fluidized bed hydrodynamics can be carried out based on geometric similarity and matching of a set of five dimensionless groups: (i)the M-group, M = g.Δρ.μ L4/(ρL2.σ 3); (ii)an Eötvös number, Eo = g.Δρ.d p2/σ (iii)the liquid Reynolds number, Re L = ρL.dp.UL/μ L; (iv)a density ratio, βd = ρp/ρ L; and (v)a superficial velocity ratio, βu = U g/UL. These were varied in an experimental study where four dimensionless hydrodynamic parameters were measured: (i)gas hold-up, ɛ g; (ii)bed expansion ratio, βbe (iii)the ratio of mean bubble diameter to particle diameter, db/dp ; and (iv)the ratio of mean bubble rise velocity to gas superficial velocity, Ub/Ug. This approach was validated experimentally by matching the dimensionless operating conditions from a kerosene-nitrogen-ceramic three-phase system with those in an aqueous magnesium sulphate solution-air-aluminum particle fluidized bed. There was good agreement between the gas hold-ups and bed expansion ratios in the two systems. A pilot-plant scale cold-flow co-current upwards-flowing three-phase fluidized bed column of inside diameter 292 mm was built and operated using three different liquids (tap water, an aqueous 44 mass % glycerol solution, and an aqueous 60 mass % glycerol solution), air, and cylindrical aluminum particles of diameter 4 mm and length 10 mm. The fluids and solids were carefully selected to result in dimensionless group values in the range of those of an industrial hydroprocessor. Specially built conductivity probes and pressure transducers were used to measure the hydrodynamic properties for different gas and liquid superficial velocities. Special attention was required to provide for drift and calibration when recording and analyzing data from the conductivity probes. Gas hold-ups were in the range of 5 to 20% by volume and were correlated as a function of liquid-phase Reynolds number and superficial velocity ratio. The gas hold-ups were a
Three-phase flow simulations in discrete fracture networks
Geiger, S.; Niessner, J.; Matthai, S. K.; Helmig, R.
2006-12-01
Fractures are often the key conduits for fluid flow in otherwise low permeability rocks. Their presence in hydrocarbon reservoirs leads to complex production histories, unpredictable coupling of wells, rapidly changing flow rates, possibly early water breakthrough, and low final recovery. Recently, it has been demonstrated that a combination of finite volume and finite element discretization is well suited to model incompressible, immiscible two-phase flow in 3D discrete fracture networks (DFN) representing complexly fractured rocks. Such an approach has been commercialized in Golder Associates' FracMan Reservoir Edition software. For realistic reservoir simulations, however, it would be desirable if a third compressible gas phase can be included which is often present at reservoir conditions. Here we present the extension of an existing node-centred finite volume - finite element (FEFV) discretization for the efficient and accurate simulations of three-component - three-phase flow in geologically realistic representations of fractured porous media. Two possible types of fracture networks can be used: In 2D, they are detailed geometrical representations of fractured rock masses mapped in field studies. In 3D, they are geologically constrained, stochastically generated discrete fracture networks. Flow and transport can be simulated for fractures only or for fractures and matrix combined. The governing equations are solved decoupled using an implicit-pressure, explicit-saturation (IMPES) approach. Flux and concentration terms can be treated with higher-order accuracy in the finite volume scheme to preserve shock fronts. The method is locally mass conservative and works on unstructured, spatially refined grids. Flash calculations are carried out by a new description of the Black-Oil model. Capillary and gravity effects are included in this formulation. The robustness and accuracy of this formulation is shown in several applications. First, grid convergence is
Voltage Control Scheme for Three Phase SVM Inverter Fed Induction Motor Drive Systems
Directory of Open Access Journals (Sweden)
U. SOWMMIYA
2010-12-01
Full Text Available This paper presents an efficient implementation scheme for the closed-loop voltage control of an induction motor incorporating ‘Space Vector Pulse Width Modulation (SVPWM‘. Voltage control is required to meet the variation in the input voltage and to regulate the output of the inverter. Space Vector Modulation (SVM is an algorithm for the control of Pulse Width Modulation (PWM. Comparative study has been made between SVM and PWM techniques. From the simulation results, SVM has reduced THD compared to pulse width modulation techniques. Thus, SVM gives better harmonic response and higher efficiency.
Lee, Ho-Young; Kang, In Man; Shon, Chae-Hwa; Lee, Se-Hee
2015-05-01
A variable inductor with magnetorheological (MR) fluid has been successfully applied to power electronics applications; however, its thermal characteristics have not been investigated. To evaluate the performance of the variable inductor with respect to temperature, we measured the characteristics of temperature rise and developed a numerical analysis technique. The characteristics of temperature rise were determined experimentally and verified numerically by adopting a multiphysics analysis technique. In order to accurately estimate the temperature distribution in a variable inductor with an MR fluid-gap, the thermal solver should import the heat source from the electromagnetic solver to solve the eddy current problem. To improve accuracy, the B-H curves of the MR fluid under operating temperature were obtained using the magnetic property measurement system. In addition, the Steinmetz equation was applied to evaluate the core loss in a ferrite core. The predicted temperature rise for a variable inductor showed good agreement with the experimental data and the developed numerical technique can be employed to design a variable inductor with a high-frequency pulsed voltage source.
Energy Technology Data Exchange (ETDEWEB)
Lee, Ho-Young; Kang, In Man, E-mail: imkang@ee.knu.ac.kr [School of Electronics Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Shon, Chae-Hwa [Korea Electrotechnology Research Institute, Changwon 642-120 (Korea, Republic of); Lee, Se-Hee, E-mail: shlees@knu.ac.kr [Department of Electrical Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of)
2015-05-07
A variable inductor with magnetorheological (MR) fluid has been successfully applied to power electronics applications; however, its thermal characteristics have not been investigated. To evaluate the performance of the variable inductor with respect to temperature, we measured the characteristics of temperature rise and developed a numerical analysis technique. The characteristics of temperature rise were determined experimentally and verified numerically by adopting a multiphysics analysis technique. In order to accurately estimate the temperature distribution in a variable inductor with an MR fluid-gap, the thermal solver should import the heat source from the electromagnetic solver to solve the eddy current problem. To improve accuracy, the B–H curves of the MR fluid under operating temperature were obtained using the magnetic property measurement system. In addition, the Steinmetz equation was applied to evaluate the core loss in a ferrite core. The predicted temperature rise for a variable inductor showed good agreement with the experimental data and the developed numerical technique can be employed to design a variable inductor with a high-frequency pulsed voltage source.
Datta, Aniket; Narayanan, G.
2016-12-01
Insulated gate bipolar transistor (IGBT) based voltage source converters use copper plates with insulating sheets in between them (sandwich bus-bar arrangement) for connecting the different device terminals in the power circuit. In such converters, the parasitic inductances in the power circuit are crucial as they cause overvoltage spikes across the device. Also, the parasitics affect the current sharing between IGBTs when they are connected in parallel in high power converters. The conduction path through plates and fasteners in the bus-bar assembly is three-dimensional and quite complex, making analytical evaluation of the stray inductance quite challenging. The first objective here is to present a simple experimental setup and experimental procedure, which are convenient for power electronic engineers, to measure the bus-bar inductance. The next objective is to carry out experimental studies on the inductances offered by different components and sub-assemblies in a bus-bar assembly. This includes evaluation of inductances of the different conduction paths in typical bus-bar plates. The third objective is to experimentally evaluate the parasitic inductances in the bus-bar assembly of a commercial 250 kVA high power converter. Each leg of this converter consists of two 300 A/1200 V IGBTs connected in parallel. The effective inductance seen by the individual device modules are determined experimentally.
Deterministic approach to microscopic three-phase traffic theory
Kerner, B S; Kerner, Boris S.; Klenov, Sergey L.
2005-01-01
A deterministic approach to three-phase traffic theory is presented. Two different deterministic microscopic traffic flow models are introduced. In an acceleration time delay model (ATD-model), different time delays in driver acceleration associated with driver behavior in various local driving situations are explicitly incorporated into the model. Vehicle acceleration depends on local traffic situation, i.e., whether a driver is within the free flow, or synchronized flow, or else wide moving jam traffic phase. In a speed adaptation model (SA-model), driver time delays are simulated as a model effect: Rather than driver acceleration, vehicle speed adaptation occurs with different time delays depending on one of the three traffic phases in which the vehicle is in. It is found that the ATD- and SA-models show spatiotemporal congested traffic patterns that are adequate with empirical results. It is shown that in accordance with empirical results in the ATD- and SA-models the onset of congestion in free flow at a...
Mathematical modeling of a three-phase trickle bed reactor
Directory of Open Access Journals (Sweden)
J. D. Silva
2012-09-01
Full Text Available The transient behavior in a three-phase trickle bed reactor system (N2/H2O-KCl/activated carbon, 298 K, 1.01 bar was evaluated using a dynamic tracer method. The system operated with liquid and gas phases flowing downward with constant gas flow Q G = 2.50 x 10-6 m³ s-1 and the liquid phase flow (Q L varying in the range from 4.25x10-6 m³ s-1 to 0.50x10-6 m³ s-1. The evolution of the KCl concentration in the aqueous liquid phase was measured at the outlet of the reactor in response to the concentration increase at reactor inlet. A mathematical model was formulated and the solutions of the equations fitted to the measured tracer concentrations. The order of magnitude of the axial dispersion, liquid-solid mass transfer and partial wetting efficiency coefficients were estimated based on a numerical optimization procedure where the initial values of these coefficients, obtained by empirical correlations, were modified by comparing experimental and calculated tracer concentrations. The final optimized values of the coefficients were calculated by the minimization of a quadratic objective function. Three correlations were proposed to estimate the parameters values under the conditions employed. By comparing experimental and predicted tracer concentration step evolutions under different operating conditions the model was validated.
ISOBUTANOL FROM SYNGAS IN A THREE PHASE SYSTEM
Energy Technology Data Exchange (ETDEWEB)
Peter Tijrn
2002-12-29
With growing interest in oxygenates as octane booster for automotive fuels, various synthesis routes for these chemicals are being investigated. Among others, alternative routes to isobutene, the C4-components in MTBE-synthesis are under investigation. A promising path to isobutene is the heterogeneously catalyzed CO-hydrogenation to isobutanol with following dehydration (Fig. 1). As shown by thermodynamical studies, the heterogeneously catalyzed CO-hydrogenation to isobutanol is not expected to experience any thermodynamic constraints. However, heterogeneous hydrogenation of CO is a very exothermic process, a problem which can only be partly solved when being conducted in a plug flow reactor. When carried out in reaction vessels with moving catalyst bed (e.g. three phase stirred tank), heat transfer problems can be resolved, along with additional benefits connected with this reactor type. Several heterogeneous catalytic systems have been under investigation for their capability of isobutanol synthesis from syngas. Most promising catalysts for an active and selective isobutanol synthesis from CO are modified high temperature methanol catalysts.
Description of the three-phase contact line expansion
Directory of Open Access Journals (Sweden)
Váchová Tereza
2014-03-01
Full Text Available Knowledge of bubble-particle interaction is important in many industrial processes such as in flotation. While the collision (first interaction sub-process between bubbles and particles is influenced only by hydrodynamic forces, the bubble behaviour during the attachment (second sub-process is influenced both by hydrodynamic and surface forces. This work is focused on the study of the three-phase contact (TPC line expansion during bubble adhesion on hydrophobic surface and on its experimental and mathematical description. The experiments were carried out in pure water where mobile bubble surface is expected. The rising bubble was studied in dynamic arrangement, whereas the stationary bubble was analysed in static arrangement. The attachment process was recorded using a high-speed digital camera and evaluated using image analysis. The diameter of the expanding TPC line as well as the dynamic contact angle was determined. Two approaches - the hydrodynamic and the molecular-kinetic - were used for mathematical description of the TPC line expansion. According to our results, the hydrodynamic model is suitable for the description of the initial fast phase of the expansion. The molecular-kinetic model was assessed as appropriate for almost whole range of TPC expansion. Parameters of the model were evaluated and compared for both types of arrangement.
Three-phase inverter for small high speed motors
Mccormick, John A.; Valenzuela, Javier A.
1991-01-01
A high-frequency three-phase inverter is being developed to drive a miniature centrifugal compressor which is a key component in a long-life space-borne cryocooler. The inverter is a unique transformer-coupled design, tailored to the low-voltage high-current characteristic of the compressor's induction motor. The design and performance demonstration of a breadboard model of the inverter are described. The cryocooler uses a reverse-Brayton cycle with turbomachines to provide 5 watt of cooling at 70 K. The design target for input power to the compressor motor is 175 watts. Line-to-neutral phase voltage waveforms to be supplied by the inverter have an amplitude of 15 volt-rms at a frequency of 8 kHz. DC power at 28 volt is supplied to the inverter. The breadboard inverter was tested with a preliminary development model of the compressor. It drove the compressor over a range of operating conditions encompassing frequencies of 5 to 9 kHz at powers of 56 to 437 watt. Inverter efficiencies, calculated from experimentally verified loss models, ranged from 89 to 95 percent over the tests. The design target on efficiency is 90 percent. The inverter was demonstrated to supply starting current adequate to overcome the starting friction of the compressor's self-acting gas bearings by a safe margin.
Description of the three-phase contact line expansion
Váchová, Tereza; Brabcová, Zuzana; Basařová, Pavlína
2014-03-01
Knowledge of bubble-particle interaction is important in many industrial processes such as in flotation. While the collision (first interaction sub-process) between bubbles and particles is influenced only by hydrodynamic forces, the bubble behaviour during the attachment (second sub-process) is influenced both by hydrodynamic and surface forces. This work is focused on the study of the three-phase contact (TPC) line expansion during bubble adhesion on hydrophobic surface and on its experimental and mathematical description. The experiments were carried out in pure water where mobile bubble surface is expected. The rising bubble was studied in dynamic arrangement, whereas the stationary bubble was analysed in static arrangement. The attachment process was recorded using a high-speed digital camera and evaluated using image analysis. The diameter of the expanding TPC line as well as the dynamic contact angle was determined. Two approaches - the hydrodynamic and the molecular-kinetic - were used for mathematical description of the TPC line expansion. According to our results, the hydrodynamic model is suitable for the description of the initial fast phase of the expansion. The molecular-kinetic model was assessed as appropriate for almost whole range of TPC expansion. Parameters of the model were evaluated and compared for both types of arrangement.
Institute of Scientific and Technical Information of China (English)
章勇高; 邝光健; 龙立中
2013-01-01
The common-mode suppression techniques with nonzero vector pulse width modulation (NZPWM) for three-phase inverters are studied. They are random state pulse width modulation (RSPWM), active zero state PWM1 (AZSPWM1), active zero state PWM3 (AZSPWM3) and near state PWM (NSPWM). Firstly, the operation areas of modulation factor and reference voltage vector with different modulation strategies are analyzed. The results show that RSPWM has a smaller operation area than other three NZPWM and is suitable for the application with lower modulation ratio. Secondly, the DC voltage utilization rate and output harmonic of different NZPWM are researched and compared with that of traditional space vector modulation (SVM) by using theoretical analysis and simulation. The results show that AZPWM1, AZPWM3 and NSPWM can not only suppress the common mode voltage of three-phase inverters efficiently, but also maintain high DC voltage utilization rate. However, three-phase inverters with NSPWM have the higher output harmonic comparing with the traditional SVM. The research results provide theoretical basis and instruction for the selection of common mode voltage suppression technique with NZPWM for three-phase inverters and its further study.% 研究了三相逆变器的 RSPWM、AZSPWM1、AZSPWM3和 NSPWM 无零矢量共模电压抑制技术。首先,分析了不同调制策略的调制因数和参考电压矢量的工作区间,说明了 RSPWM 的工作区间较小,适用于低调制比工作场合。再次,利用理论分析和仿真方法,研究了无零矢量调制策略的直流电压利用率和输出谐波特性,并与传统 SVM 调制策略比较。结果表明,AZSPWM1、AZSPWM3和 NSPWM 调制策略能够有效地抑制三相逆变器共模电压,同时保持了较高的直流电压利用率。但相对 SVM 调制策略,三相逆变器的输出谐波含量有所增大。研究结果为三相逆变器的无零矢量共模电压抑制技术的选用及进一步研究提供了理论依据和指导。
Institute of Scientific and Technical Information of China (English)
朱晋; 韦统振; 李东; 贾东强; 马明
2013-01-01
Alternate-arm multi-level converter (A2MC) is a new voltage source converter high voltage direct current transmission (VSC-HVDC) converter topology. This paper describes the principle of a improved full-bridge alternate-arm multi-level converter. Sub-unit capacitance parameters are designed based on the energy balancing of the arm. A simple and effective voltage control strategy and bridge arm inductance parameter selection method is given to balance the sub-unit capacitor voltage. The correctness and feasibility of the present control strategy and capacitance and inductance parameter design method are verified by the three-phase simulation model built in PSIM and single-phase prototype built in the laboratory.% 变桥臂多电平变流拓扑(alternate-arm multi-level converter，A2MC)是应用于电压源换流器直流输电的新型多电平换流器拓扑。该文阐述了一种新型全桥变桥臂多电平变流拓扑(full-bridge alternate-arm voltage source converter, FA2MC)的工作原理；针对该新型换流器拓扑，从桥臂能量平衡的角度，对其子单元电容参数进行了合理设计，并针对各子单元电容电压均衡的问题，给出了一种简单有效的电压控制策略及桥臂电感参数选取依据。对该拓扑进行了三相并网模型 PSIM 仿真，并在实验室制作了单相样机，得到的仿真及实验波形验证了该拓扑结构的电容电感参数设计及子单元电容恒压策略的正确性和可行性。
Energy Technology Data Exchange (ETDEWEB)
Suul, Jon Are
2012-03-15
Three-Phase Voltage Source Converters (VSCs) are finding widespread applications in grid integrated power conversion systems. The control systems of such VSCs are in an increasing number of these applications required to operate during voltage disturbances and unbalanced conditions. Control systems designed for grid side voltagesensor-less operation are at the same time becoming attractive due to the continuous drive for cost reduction and increased reliability of VSCs, but are not commonly applied for operation during unbalanced conditions. Methods for voltage-sensor-less grid synchronization and control of VSCs under unbalanced grid voltage conditions will therefore be the main focus of this Thesis. Estimation methods based on the concept of Virtual Flux, considering the integral of the converter voltage in analogy to the flux of an electric machine, are among the simplest and most well known techniques for achieving voltage-sensor-less grid synchronization. Most of the established techniques for Virtual Flux estimation are, however, either sensitive to grid frequency variations or they are not easily adaptable for operation under unbalanced grid voltage conditions. This Thesis addresses both these issues by proposing a simple approach for Virtual Flux estimation by utilizing a frequency-adaptive filter based on a Second Order Generalized Integrator (SOGI). The proposed approach can be used to achieve on-line frequency-adaptive varieties of conventional strategies for Virtual Flux estimation. The main advantage is, however, that the SOGI-based Virtual Flux estimation can be arranged in a structure that achieves inherent symmetrical component sequence separation under unbalanced conditions. The proposed method for Virtual Flux estimation can be used as a general basis for voltage-sensor-less grid synchronization and control during unbalanced conditions. In this Thesis, the estimated Virtual Flux signals are used to develop a flexible strategy for control of active
三相ZVS逆变器磁链轨迹%Locus of Flux Linkage for Three-Phase ZVS Inverter
Institute of Scientific and Technical Information of China (English)
陈国呈; 许春雨; 孙承波; 屈克庆; Taniguchi Katsunori
2005-01-01
ZVS(zero voltage switching) PWM(pulse width modulation) inverters have attracted much attention recently. The basic idea is to use ZVS circuit as the main circuit of inverter resonance at the beginning of every carrier period so that each power device can commutate when voltage of the main circuit' s DC bus line is zero. To ensure the resonant circuit to operate properly, sawtooth with alternate slope (positive or negative) is used as carrier. But the time of zero voltage vectors with such PWM pattern is greatly different from traditional hard-switching PWM pattern. This paper discusses the locus of flux linkage under soft-switching PWM pattern by using space voltage vector. It is pointed out that, under the hard-switching PWM pattern, speed of flux linkage is adjusted by zero space voltage vector. When soft-switching PWM pattern is used, however, effective time of space voltage vector varies considerably, sometimes even without zero space voltage vector. Therefore non-zero space voltage vector has been used to make the speed of flux linkage locus equal to that of hard-switching PWM pattern. The cause of current distortion in soft-switching PWM inverters is also discussed. Based on the flux linkage locus circle, corresponding compensation methods are proposed. Experimental results show that the described method can effectively improve output current waveform of inverter.
A novel three-phase UPS system with a single-phase resonant HF link
Darwish, MK
2006-01-01
This paper presents a new three-phase uninterruptible power supply (UPS) system based on a single-phase resonant high frequency (HF) link and a single-phase transformer. The three-phase output voltage is constructed and regulated from a three-phase cycloconverter fed from the constant amplitude, constant frequency link voltage. The generation of a novel switching stategy for the three-phase cycloconverter is presented. The simulation of the proposed system is carried out and verified with exp...
Directory of Open Access Journals (Sweden)
Wu Cao
2015-02-01
Full Text Available Compared with the three-phase, two-split-capacitor active power filter (3P2C-APF, the three-phase, four-leg active power filter (3P4L-APF has been widely used in three-phase, four-wire grid utility for power quality control due to its numerous advantages, such as higher current output capability, particularly in phase N, lower current and easier voltage control on the DC-side. However, designing the grid-connecting interface, which is between the voltage source converter (VSC and grid utility, is rather difficult due to the higher requirement for current ripple filtering in phase N, cross-coupling in four phases and lack of relevant design methodology and specification. In this paper, a four-branch LCL-type (4B-LCL grid-connecting interface is proposed for 3P4L-APF, which features better current ripple filtering performance without decreasing the current output capability in all phases. First, this paper describes the mathematical models of 4B-LCL in the fully-complex-vector form from the zero and non-zero sequence perspective, resulting in two independent and uniform equivalent circuits without cross coupling terms. Then, the 4B-LCL parameter design method based on the most comprehensive performance index is proposed, including three main stages as the specification: performance index requirement determination, fulfillment of that requirement, and verification. Finally, the validity and effectiveness of the proposed design are proven by the simulated and experimental results of a 3P4L-APF with 4B-LCL.
ADVANCED COMPUTATIONAL MODEL FOR THREE-PHASE SLURRY REACTORS
Energy Technology Data Exchange (ETDEWEB)
Goodarz Ahmadi
2004-10-01
In this project, an Eulerian-Lagrangian formulation for analyzing three-phase slurry flows in a bubble column was developed. The approach used an Eulerian analysis of liquid flows in the bubble column, and made use of the Lagrangian trajectory analysis for the bubbles and particle motions. The bubble-bubble and particle-particle collisions are included the model. The model predictions are compared with the experimental data and good agreement was found An experimental setup for studying two-dimensional bubble columns was developed. The multiphase flow conditions in the bubble column were measured using optical image processing and Particle Image Velocimetry techniques (PIV). A simple shear flow device for bubble motion in a constant shear flow field was also developed. The flow conditions in simple shear flow device were studied using PIV method. Concentration and velocity of particles of different sizes near a wall in a duct flow was also measured. The technique of Phase-Doppler anemometry was used in these studies. An Eulerian volume of fluid (VOF) computational model for the flow condition in the two-dimensional bubble column was also developed. The liquid and bubble motions were analyzed and the results were compared with observed flow patterns in the experimental setup. Solid-fluid mixture flows in ducts and passages at different angle of orientations were also analyzed. The model predictions were compared with the experimental data and good agreement was found. Gravity chute flows of solid-liquid mixtures were also studied. The simulation results were compared with the experimental data and discussed A thermodynamically consistent model for multiphase slurry flows with and without chemical reaction in a state of turbulent motion was developed. The balance laws were obtained and the constitutive laws established.
High flexibility and low cost digital implementation for modern PWM strategies
DEFF Research Database (Denmark)
Mathe, Laszlo; Sera, Dezso; Kerekes, Tamas
2011-01-01
like AZSPWM, NSPWM, or ACRPWM. By using a conventional PWM unit from a microcontroller, these modern modulation techniques are often difficult, or even impossible, to implement. The proposed method can be used to implement PWM strategies even for those microcontrollers which are not equipped...
Development of a PWM precision spraying controller for unmanned aerial vehicles
This paper presents a new pulse width modulation (PWM) controller for unmanned aerial vehicle (UAV) precision sprayer for agriculture using a TL494 fix-frequency pulse width modulator together with a data acquisition board and developed software. The PWM controller was implemented through the guidan...
Influence of PWM Modes on Commutation Torque Ripples in Sensorless Brushless DC Motor Control System
Institute of Scientific and Technical Information of China (English)
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.
Control Strategies for Trap Filter Interfaced Three-Phase Grid Connected Converters
DEFF Research Database (Denmark)
Min, Huang
In order to utilize renewable energy systems power electronics are needed to convert the energy to grid. The AC-DC and DC-AC power conversion are dominant in wind power system and photovoltaic system. However, the use of PWM scheme introduces undesirable harmonics. In order to enhance the grid in...
DEFF Research Database (Denmark)
Xiao, Lei; Huang, Shoudao; Lu, Kaiyuan
2013-01-01
Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this......Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load....... In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component...
Instantaneous Power Compensation in Three-Phase Systems by Using p-q-r Theory
DEFF Research Database (Denmark)
Kim, Hyosung; Blaabjerg, Frede; Bak-Jensen, Birgitte;
2002-01-01
Three linearly independent instantaneous powers have been defined in the time domain in three-phase four-wire systems with the use of p-q-r theory. Any three-phase circuit can be transformed into three single-phase circuits by the p-q-r transformation Thus the instantaneous powers in any three-phase...... systems can be analysed as the same way of instantaneous power in single-phase systems.This paper analyses the instantaneous powers spectrally in the frequency domain for single-phase systems and three-phase systems. Each instantaneous power in three-phase systems has its own spectral pattern...... that is characterized by the spectral distribution of the system voltages and currents. The instantaneous power in single-phase systems has its own spectral pattern different from that of three-phase systems.From the spectral analysis of the instantaneous powers, powers are newly defined in the frequency domain...
Single-phase vs. Three-phase High Power High Frequency Transformers
Xue, Jing
2010-01-01
This thesis proposes one comparison methodology for single and three-phase high power high frequency transformers in power conversion systems. The objective is to compare the volume of the transformers. And single and three-phase Dual Active Bridge Converter (DAB1 and DAB3) topologies with single and three-phase isolating transformers are selected for the transformer comparison. Design optimization of power transformer has been studied and simplified models have been built for the single and ...
Vector Control of Three-Phase Induction Motor with Two Stator Phases Open-Circuit
Seyed Hesam Asgari; Mohammad Jannati; Tole Sutikno; Nik Rumzi Nik Idris
2015-01-01
Variable frequency drives are used to provide reliable dynamic systems and significant reduction in usage of energy and costs of the induction motors. Modeling and control of faulty or an unbalanced three-phase induction motor is obviously different from healthy three-phase induction motor. Using conventional vector control techniques such as Field-Oriented Control (FOC) for faulty three-phase induction motor, results in a significant torque and speed oscillation. This research presented a no...
Soft-switching PWM full-bridge converters topologies, control, and design
Ruan, Xinbo
2014-01-01
Soft-switching PWM full-bridge converters have been widely used in medium-to-high power dc-dc conversions for topological simplicity, easy control and high efficiency. Early works on soft-switching PWM full-bridge converter by many researchers included various topologies and modulation strategies. However, these works were scattered, and the relationship among these topologies and modulation strategies had not been revealed. This book intends to describe systematically the soft-switching techniques for pulse-width modulation (PWM) full-bridge converters, including the topologies, control and
Synchronization of the distributed PWM carrier waves for modular multilevel converters
DEFF Research Database (Denmark)
Burlacu, Paul Dan; Mathe, Laszlo; Teodorescu, Remus
2014-01-01
The half-bridge modular multilevel converter has proven itself to be a suitable solution for HVDC application. In order to achieve high modularity and fault tolerance, distributed control strategy is one possible solution and is discussed in this paper. When distributed control strategy is used, ...... the PWM outputs of each sub-module increasing the total harmonic distortion of the output voltage. This paper presents a solution to synchronize the PWM outputs of the MMC submodules using EtherCAT communication protocol focusing on phase shifted PWM modulation technique....
Parallel Interleaved VSCs: Influence of the PWM Scheme on the Design of the Coupled Inductor
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Maheshwari, Ram Krishan;
2014-01-01
-linkage in the CI is presented in this paper. The maximum flux density and the core losses, being the most important parameters for the CI design, are evaluated for continuous PWM and discontinuous pulsewidth modulation (DPWM) schemes. The effect of these PWM schemes on the design of the CI is discussed....... To limit the circulating current, magnetic coupling between the interleaved legs of the corresponding phase is provided by means of a Coupled Inductor (CI). The design of the CI is strongly influenced by the Pulsewidth Modulation (PWM) scheme used. The analytical model to evaluate the flux...
Efficiency analysis on a two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Geng, Pan; Wu, Weimin; Huang, Min;
2013-01-01
for non-conventional inverters with special shoot-through state is introduced and illustrated through the analysis on a special two-level three-phase quasi-soft-switching inverter. Efficiency comparison between the classical two-stage two-level three-phase inverter and the two-level three-phase quasi......-soft-switching inverter is carried out. A 10 kW/380 V prototype is constructed to verify the analysis. The experimental results show that the efficiency of the new inverter is higher than that of the traditional two-stage two- level three-phase inverter....
Single Phase Bidirectional PWM Converter for Microgrid System
Directory of Open Access Journals (Sweden)
C.Kalavalli
2013-06-01
Full Text Available Smart grid is a newly flourishing research area because of its viable applications and expected to address the drawback of existing grid. Microgrids are the part of the Smart grid and they are designed to supply electricity for a small community such as residential areas, universities or industrial sites. Power electronics plays a vital role for connecting the renewable energy sources to Microgrid system. This paper deals the Microgrid connected single phase Bidirectional PWM converter which operates in Rectification and Inverting mode. This converter helps to connect renewable energy sources to loads as well as excess power are given to power grid. Double Loop PID control technique is used for controlling the converter for both modes. The designed Converter is simulated in MATLAB/Simulink software and results are verified using the Hardware.
Parametric algorithms for frequency estimation in PWM converter systems
Energy Technology Data Exchange (ETDEWEB)
Lobos, T.; Hejke, I.; Rezmer, J.; Sikorski, T.; Kostyla, P. [Dept. of Electrical Engineering, Wroclaw University of Technology, Wyb. Wyspianskiego 27, 50-370 Wroclaw (Poland)
2009-11-15
Proper estimation of voltage parameters has a significant meaning for power converters control systems. One of the measured parameter, directly associated with control process, is frequency of the basic voltage component at the converter output. Unfortunately, power converters generate a wide spectrum of harmonics as well as interharmonics, that makes difficulties in estimation this frequency. Measurement carried out in industrial applications exhibits complex nature of investigated signals often corrupted by resonances or overvoltages phenomena. It entails searching a new digital algorithms for frequency measurement. This work presents algorithm using modification of high-resolution Prony method connected with digital filtering. The investigations was based on simulations and real measured signals recorded in two different commercial PWM converters. Obtained results indicate accuracy of the method as well as its fast response. (author)
Stator insulation systems for medium voltage PWM drives fed motors
Energy Technology Data Exchange (ETDEWEB)
Gao, G.; Chen, W. [TECO-Westinghouse Motor Co., Round Rock, TX (United States)
2005-07-01
Adjustable speed drives (ASD) are commonly used in power electronics and control systems. It is estimated that more than 15 per cent of medium voltage motors are currently fed by such drives worldwide. A research project was conducted to examine the influence of medium voltage pulse width modulated (PWM) ASD on motor stator insulation systems. The findings, based on accelerated laboratory tests, have helped designers to improve the capabilities of the insulation system used for ASD-fed motors. Repetitive, high magnitude voltage spikes with fast rise time create significant stress on insulation systems. Gradual deterioration and premature failure of the motor insulation can result from surge voltages which generate surface discharges between phase windings/end windings, or partial discharges between stator turns. However, there is no industrial standard to evaluate motor insulation life under ASD-cable-motor conditions. Several material manufacturers have developed their own version of corona resistant material. However, the insulation life of ASD-fed motors does not depend solely on the raw materials. Rather, it depends on the complete insulation system, including the stator manufacturing process. In order to address this problem, TECO-Westinghouse Motor Company has developed special design criteria and manufacturing practices in order to reduce winding insulation temperature and to compensate for the additional heat generated by high frequency contents in the PWM voltage waveform. A patent pending new cooling system should reduce winding temperature by 15 to 20 degrees C. This paper presented design considerations for turn insulation, groundwall insulation, and a voltage stress grading system. A new thermal class H insulation system was also described. 6 refs., 2 tabs., 5 figs.
Indian Academy of Sciences (India)
M Vijayakumar; S Vijayan
2014-08-01
This paper proposes a Photovoltaic (PV)-based three-phase four-wire Series Hybrid Active Power Filter (SHAPF), it comprises of a Series Active Power Filter (SAPF) and an LC shunt passive filter. The proposed system eliminates both the current and voltage harmonics and compensates reactive power, neutral current and voltage interruption. A SAPF demands a source of energy for compensating the voltage sag/swell. This system found a new topology for SHAPF which utilizes the PV with DC–DC boost converter as a source of DC power for the series active filter. The compensation current reference evaluation is based on the twin formulation of the vectorial theory of electrical power theorem with Fuzzy Logic Controller (FLC). The PV array/battery managed DC–DC boost converter is employed to step up the voltage to meet the DC bus voltage requirement of the three-leg Voltage Source Inverter (VSI). The foremost benefit of the proposed system is that, it will provide uninterrupted compensation for the whole day. This system utilizes the renewable energy; accordingly saves the energy and provides the uninterruptable power supply to critical/sensitive load, through the PV array/battery bank during both day time and night time. An experimental model was established and results were obtained, which indicated the capability of the proposed control scheme.
Institute of Scientific and Technical Information of China (English)
毛惠丰; 孔德鹏; 陈增禄; 杨旭; 王兆安
2015-01-01
提出了一种单相 H 桥电压型逆变器三电平滞环电流跟踪控制方法。该控制方法具有载波移相PWM调制效果以及无死区效应的特点。在稳态条件下，误差电流被严格限制在内环中。当指令电流发生突变并且达到外环的上或下阈值时，逆变器输出最高或最低电平以使误差电流以最快速度趋近于0。与传统的三电平滞环电流控制方法相比，该控制方法能进一步改善逆变器输出电流的波形。通过仿真和实验结果验证了该方法的有效性。%ABSTRACT:A new three-level hysteresis current controller for single-phase H-bridge voltage source inverters (VSI) is proposed here. The proposed hysteresis current controller has successfully combined the advantage of the symmetrical unipolar carrier-based PWM and no dead-time effects. Under steady-state conditions, the current error will be confined within the inner band. When the commanded current step changes so that the current error exceeds the outer hysteresis band, the extreme voltage level is selected to force the current error towards zero quickly. Compared with the conventional three-level hysteresis current controller, the proposed hysteresis current controlled single-phase H-bridge voltage source inverters can further improve the inverter output current waveform. Simulated and experimental results have been given to demonstrate the validity and features of the novel hysteresis current controller with the improved switching scheme.
PWM Switching Frequency Effects on Eddy Current Sensors for Magnetically Suspended Flywheel Systems
Jansen, Ralph; Lebron, Ramon; Dever, Timothy P.; Birchenough, Arthur G.
2003-01-01
A flywheel magnetic bearing (MB) pulse width modulated power amplifier (PWM) configuration is selected to minimize noise generated by the PWMs in the flywheel position sensor system. Two types of noise are addressed: beat frequency noise caused by variations in PWM switching frequencies, and demodulation noise caused by demodulation of high order harmonics of the switching voltage into the MB control band. Beat frequency noise is eliminated by synchronizing the PWM switch frequencies, and demodulation noise is minimized by selection of a switching frequency which does not have harmonics at the carrier frequency of the sensor. The recommended MB PWM system has five synchronized PWMs switching at a non-integer harmonic of the sensor carrier.
Leakage Current Elimination of Four-Leg Inverter for Transformerless Three-Phase PV Systems
DEFF Research Database (Denmark)
Guo, Xiaoqiang; He, Ran; Jian, Jiamin;
2016-01-01
Eliminating the leakage current is one of the most important issues for transformerless three phase photovoltaic (PV) systems. In this paper, the leakage current elimination of a three-phase four-leg PV inverter is investigated. With the common mode loop model established, the generation mechanism...
Three-Phase and Six-Phase AC at the Lab Bench
Caplan, George M.
2009-01-01
Utility companies generate three-phase electric power, which consists of three sinusoidal voltages with phase angles of 0 degrees, 120 degrees, and 240 degrees. The ac generators described in most introductory textbooks are single-phase generators, so physics students are not likely to learn about three-phase power. I have developed a simple way…
Diagnosis of the three-phase induction motor using thermal imaging
Glowacz, Adam; Glowacz, Zygfryd
2017-03-01
Three-phase induction motors are used in the industry commonly for example woodworking machines, blowers, pumps, conveyors, elevators, compressors, mining industry, automotive industry, chemical industry and railway applications. Diagnosis of faults is essential for proper maintenance. Faults may damage a motor and damaged motors generate economic losses caused by breakdowns in production lines. In this paper the authors develop fault diagnostic techniques of the three-phase induction motor. The described techniques are based on the analysis of thermal images of three-phase induction motor. The authors analyse thermal images of 3 states of the three-phase induction motor: healthy three-phase induction motor, three-phase induction motor with 2 broken bars, three-phase induction motor with faulty ring of squirrel-cage. In this paper the authors develop an original method of the feature extraction of thermal images MoASoID (Method of Areas Selection of Image Differences). This method compares many training sets together and it selects the areas with the biggest changes for the recognition process. Feature vectors are obtained with the use of mentioned MoASoID and image histogram. Next 3 methods of classification are used: NN (the Nearest Neighbour classifier), K-means, BNN (the back-propagation neural network). The described fault diagnostic techniques are useful for protection of three-phase induction motor and other types of rotating electrical motors such as: DC motors, generators, synchronous motors.
Electrical Discharge Machining Flyback Converter using UC3842 Current Mode PWM Controller
Directory of Open Access Journals (Sweden)
Nazriah Mahmud
2014-10-01
Full Text Available This paper presents a current mode Pulse Width Modulation (PWM controlled Flyback converter using UC3842 for Electrical Discharge Machining current generator control circuit. Circuit simplicity and high efficiency can be achieved by a Flyback converter with current mode PWM controller. The behaviors of the system's operation is analyzed and discussed by varying the load resistance. Matlab sofware is used to simulate the Flyback converter where a prototype has been built and tested to verify it's performance.
Analysis of VCO based noise shaping ADCs linearized by PWM modulation
Hernandez, Luis; Prefasi, , Enrique; Paton , Susana; Rombouts, Pieter
2012-01-01
Nonlinearity is one of the main problems associated with VCO based noise shaping ADCs. Their open loop architecture does not permit correction of the nonlinear voltage to frequency response of the VCO by feedback. Recently, linearization of a VCO ADC by Pulse Width Modulation (PWM) precoding has been proposed. Here, the input signal is encoded by a PWM modulator to drive the VCO with a 2-level signal, thus eliminating the nonlinearity of the VCO. This paper analyzes the remaining inherent dis...
Positioning Error of Optoelectronic Telescope Compensated by Bipolar PWM Driving Mode
Institute of Scientific and Technical Information of China (English)
LI Xiao-yan; ZHOU Hui; FU Hong; HOU Yun-hai
2005-01-01
The optoelectronic telescope has two sets of control systems: azimuth one and elevation one, and both are driven by PWM power amplifier with high efficiency and wide speed regulation range. The diagram of the azimuth control system is demonstrated, the nonlinear factors is analyzed at low speed, and some related experiments are carried out. The results show that the positioning error with unipolar is 86 codes(106.21″),while 18 codes (22. 23″) is with bipolar PWM driver.
Design of benchmark voltage source based on single N-type process%基于N型工艺的基准电压源设计
Institute of Scientific and Technical Information of China (English)
李仲秋
2011-01-01
A kind of generating benchmark voltage circuit is designed integrating with only n-type active device and passive components process by using op-amp of the feedback closed-loop control method to generate benchmark voltage based on the traditional complementary type bandgap benchmark voltage source in only n-type active device technology.It provides a good power supply rejection ratio characteristics and the benchmark voltage source circuit of effectively compensating the negative temperature coefficient on n-type device pressure drop changes for only existing n-type MOS or NPN transistor,no P type device,difficultly using conventional bandgap voltage source structure to produt specific technology of accurate reference voltage,and the measures to improve the feedback loop stability are put forward.%针对传统互补型带隙基准电压源在只有N型有源器件工艺中的局限性,采用运放反馈的闭环控制方法来产生基准电压,设计了一种可以集成于只有N型有源器件和无源元件工艺中的基准电压源产生电路。为只存在N型MOS或者NPN型晶体管、没有P型器件、难以用传统的带隙电压源结构来产生精确参考电压的特定工艺,提供了一种具有良好的电源抑制比特性和有效地补偿N型器件结压降变化的负温度系数的基准电压源电路;并提出了提高反馈回路稳定性的措施。
30 CFR 75.901 - Protection of low- and medium-voltage three-phase circuits used underground.
2010-07-01
... auto-transformer is used. (see Figure III in Appendix A to subpart J of this part) (3) Each three-phase...-fault current transformers. (5) Each three-phase circuit interrupting device must be provided with a...-voltage three-phase circuits used underground. (a) Low- and medium-voltage three-phase...
Directory of Open Access Journals (Sweden)
Ufa Ruslan A.
2014-01-01
Full Text Available The motivation of the presented research is based on the needs for development of new methods and tools for adequate simulation of Flexible Alternating Current Transmission System (FACTS devices and High Voltage Direct Current Transmission (HVDC system as part of real electric power systems (EPS. For that, a hybrid approach for advanced simulation of the FACTS and HVDC based on Voltage Source is proposed. The presented simulation results of the developed hybrid model of VSC confirm the achievement of the desired properties of the model and the effectiveness of the proposed solutions.
A modified two-level three-phase quasi-soft-switching inverter
DEFF Research Database (Denmark)
Liu, Yusheng; Wu, Weimin; Blaabjerg, Frede;
2014-01-01
to reduce the extra conduction power loss and the voltage stress across the DC-link capacitor, a modified two-level three-phase quasi-soft-switching inverter is proposed by using a SiC MOSFET instead of an IGBT. The principle of the modified two-level three-phase quasi-soft-switching inverter is analyzed...... in detail. And the performance is verified through simulations and experiments on a 5 kW/380 V three-phase prototype....
DPC controlled three-phase active filter for power quality improvement
Energy Technology Data Exchange (ETDEWEB)
Chaoui, Abdelmadjid; Krim, Fateh [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif (Algeria); Gaubert, Jean-Paul; Rambault, Laurent [Laboratoire d' Automatique et d' Informatique Industrielle (LAII-ESIP), Universite de Poitiers (France)
2008-10-15
This paper presents a new control method entitled direct power control (DPC) for shunt active power filtering (5th, 7th, 11th,..) (SAPF), which is applied to eliminate line current harmonics and compensate reactive power. Its main goal is to rebuild active and reactive powers to be compared to references values using hysteresis control. The outputs of hysteresis controllers associated with a switching table, control the instantaneous active and reactive power by selecting the optimum switching state of the voltage source inverter (VSI). A theoretical analysis with a complete simulation of the system and experimental results are presented to prove the excellent performance of the proposed control technique. (author)
Three-phase anti-interference unbalanced electronic load simulator%三相抗干扰性不平衡电子负载模拟装置
Institute of Scientific and Technical Information of China (English)
田铭兴; 刘芳
2011-01-01
A three-phase unbalanced load electronic simulator is designed,which applies an AC/DC/AC bidirectional PWM inverter as its main circuit and the decoupled active and reactive power controls to simulate the three-phase unbalanced load and realize the bidirectional power flow. Based on the three-phase instantaneous reactive power theory,the command current is deduced by the real-time detection of single -phase current harmonies and reactive current to eliminate the impact of grid voltage initial phase for improving its anti-interference performance. Simulation with Matlab demonstrates the feasibility and rationality of its design and the simulative waveforms show that,with excellent anti-interference performance,the simulator eliminates the disturbances from power grid.%设计了一种三相不平衡电子负载模拟装置.该装置采用AC/DC/AC双PWM变流器为主电路结构,通过有功功率和无功功率的解耦控制来模拟三相不平衡电子负载特性,同时能实现能量的双向流动.提出以三相电路瞬时无功功率理论为基础的单相电路谐波和无功电流实时检测方法来推导指令电流,使指令电流不受电网电压初始相位的影响,从而提高装置的抗干扰性.通过Matlab仿真来验证该装置设计方案的可行性和合理性,仿真波形说明该电子负载模拟装置能够消除电网扰动所带来的干扰,具有较强的抗干扰作用.
Analysis of Single Phase PWM Rectifier for Different Applications
Mitra, Arkendu; Chowdhuri, Sumana
2016-06-01
This research work investigates the various applications of a PWM rectifier based on its input power factor. Most of the cases, the papers describe the operation of the rectifier used for unity power factor (UPF) operation. Beside this mode of operation, this paper compiles the application of the rectifier as STATCOM also, where the rectifier deals only with reactive power exchange. In this work, the controller is implemented by inserting a loop for reference input of phase angle which will be compared with the actual one, so that user can operate the rectifier at any power factor. Some basic formulae are derived for the input current, active power and reactive power based on which the control circuit is to be designed. Here two Proportional-Integral (PI) controllers are used. A brief description of tuning these two PI controllers is incorporated in this paper. Also some calculations are given to determine the harmonic factors of the input line current from which it is found that the rectifier when operated in each mode operation, the order of the harmonics are very low.
Institute of Scientific and Technical Information of China (English)
张伟龙; 谢新胜; 李帅
2013-01-01
With the continuous development of power electronics technology and mature, As the importance of power electronics technology and simulation applications. PWM and SPWM technology and PSIM software will certainly be with the power electronics technology development is recognized by more and more people. This paper simply introduces the technology of the most basic concepts, with PSIM software to deepen the understanding of them, Let us in the future life and work have a basic understanding of and cognition, also make a foundation for future learning.%随着电力电子技术的不断发展与成熟，电力电子在各个方面都得到了广泛的应用。而作为电力电子技术的重要技术和仿真应用软件，PWM与SPWM技术及PSIM软件必然会随着电力电子技术的发展被越来越多的人所认识。本文通过简单地介绍这项技术的最基本概念，并用PSIM软件来加深对它们的理解，让大家在日后的生活和工作有一个基本的了解和认识，也为今后的学习打一个基础。
PWM-Statcom system additionally having active filter function
Energy Technology Data Exchange (ETDEWEB)
Matsui, K.; Kojima, H.; Yamamoto, I.; Hasegawa, M. [Chubu Univ., Kasugai Aichi (Japan); Ando, K. [Nitto Kogyo Corp., Nagakute, Aichi (Japan)
2006-07-01
The harmonic characteristics of static synchronous compensators (Statcom) were discussed with particular reference to the difference between symmetrical and asymmetrical modulation strategies that influence a quality of output waveform. The asymmetrical modulation strategy is the better approach in higher power factor applications such as alternating current (AC) motor drives. It was noted that in cases requiring a passive filter with a very large scale Statcom, a symmetrical modulation strategy is superior. Therefore, in this study, a symmetrical modulation was preferred for a neutral point clamped (NPC) pulse width modulation (PWM) inverter. Due to switching in a limited narrow frequency band, such output harmonics can be eliminated using a simple passive filter and harmonics such as the fifth and the seventh, can be suppressed using the proposed Statcom scheme in which the feedback signals for the fifth and seventh harmonics are injected into the Statcom. Using these feedback signals, the harmonics in the power system were significantly reduced. This result was also confirmed by simulation. It was concluded that, in addition to the proper operation of the Statcom, it is possible to perform an active filtering function . 10 refs., 1 tab., 9 figs.
Vector Control of Three-Phase Induction Motor with Two Stator Phases Open-Circuit
Directory of Open Access Journals (Sweden)
Seyed Hesam Asgari
2015-06-01
Full Text Available Variable frequency drives are used to provide reliable dynamic systems and significant reduction in usage of energy and costs of the induction motors. Modeling and control of faulty or an unbalanced three-phase induction motor is obviously different from healthy three-phase induction motor. Using conventional vector control techniques such as Field-Oriented Control (FOC for faulty three-phase induction motor, results in a significant torque and speed oscillation. This research presented a novel method for vector control of three-phase induction motor under fault condition (two-phase open circuit fault. The proposed method for vector control of faulty machine is based on rotor FOC method. A comparison between conventional and modified controller shows that the modified controller has been significantly reduced the torque and speed oscillations.
A reverse mode of three-phase asynchronous motors with hexaphase windings
Directory of Open Access Journals (Sweden)
V.D. Lushchyk
2014-04-01
Full Text Available A reverse operation feasibility in three-phase asynchronous motors with the stator hexaphase windings is proved. In the reverse mode, the hexaphase windings are shown to keep all their declared advantages.
MODELING OF SYMMETRIC THREE-PHASE ASYNCHRONOUS ELECTRIC MOTOR IN ASYMMETRIC CONNECTION TO NETWORK
Directory of Open Access Journals (Sweden)
V. I. Lukovnikov
2005-01-01
Full Text Available The paper shows how to solve the problem concerning reveal of changes in mathematical models and electric parameters of symmetric three-phase short-circuited asynchronous electric motors in case of their connection to single- or two-phase network in comparison with their connection to three-phase network. The uniform methodological approach permitting to generalize the known data and receive new results is offered in the paper.
Kerner, B. S.; Klenov, S. L.; Brakemeier, A.
2007-01-01
A testbed for wireless vehicle communication based on a microscopic model in the framework of three-phase traffic theory is presented. In this testbed, vehicle motion in traffic flow and analyses of a vehicle communication channel access based on IEEE 802.11e mechanisms, radio propagation modeling, message reception characteristics as well as all other effects associated with ad-hoc networks are integrated into a three-phase traffic flow model. Based on simulations of this testbed, some stati...
A Three-Phase Bidirectional DC-DC Converter for Automotive Applications
Energy Technology Data Exchange (ETDEWEB)
Su, Gui-Jia [ORNL; Tang, Lixin [ORNL
2008-01-01
This paper presents a three-phase soft-switching, bidirectional dc-dc converter for high-power automotive applications. The converter employs dual three-phase active bridges and operates with a novel asymmetrical but fixed duty cycle for the top and bottom switches of each phase leg. Simulation and experimental data on a 6-kW prototype are included to verify the novel operating and power flow control principles.
The analysis of magnesium oxide hydration in three-phase reaction system
Energy Technology Data Exchange (ETDEWEB)
Tang, Xiaojia; Guo, Lin; Chen, Chen; Liu, Quan; Li, Tie; Zhu, Yimin, E-mail: ntp@dlmu.edu.cn
2014-05-01
In order to investigate the magnesium oxide hydration process in gas–liquid–solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid–solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH){sub 2} precipitation, Mg(OH){sub 2} peeling off from MgO particle and leaving behind fresh MgO surface. - Graphical abstract: There was existence of a peeling-off process in the gas–liquid–solid (three-phase) MgO hydration system. - Highlights: • Magnesium oxide hydration in gas–liquid–solid system was investigated. • The experimental data in three-phase system could be fitted well by two models. • The morphology analysis suggested that there was existence of a peel-off process.
Three-Phase Capillary Pressure, Hysteresis and Trapping in a Porous Glass-Bead Column
Andersson, L.; Schlüter, S.; Li, T.; Brown, K. I.; Helland, J. O.; Wildenschild, D.
2015-12-01
Enhanced oil recovery (EOR) strategies employing water-alternate-gas (WAG) injections may improve oil mobility and production recovery. WAG injections for EOR create regions in the reservoir with simultaneous flow of oil, water and air dominated by capillary and gravity forces. As a result of the dynamics in the transition zones, the invading fluid may snap off compartments of the displaced fluid which could then be trapped in the pore space, contributing to the hysteresis of the three-phase capillary pressure curves. Three-phase capillary pressure curves are needed to model the three-phase transition zone movements in the reservoir. In reservoir simulation models, the common practice has been to implement three-phase capillary pressure curves based on two-phase gas-oil and oil-water capillary pressure data. However, experimental and modelling studies of three-phase fluid distributions at the pore scale have shown that this procedure is not always valid; three-phase capillary pressure curves exhibit hysteresis and depend on the saturation history of the three phases which cannot be derived from two-phase capillary pressure curves. We have developed three-phase experiments that provide capillary pressures and 3D-image data of fluid distributions in the entire saturation space of oil, water and air in water-wet porous glass-bead columns; a time-consuming and technically challenging exercise. The 3D data with a resolution of 6.38 μm were derived from high-resolution synchrotron x-ray computed micro-tomography (CMT), collected at the GSECARS beam line 13-BM-D at the Advanced Photon Source, Argonne National Laboratory. In particular, we discuss how three-phase pore-scale mechanisms, such as oil layer existence and multiple displacement events, affect the mobility and trapping of oil in the porous medium. We also show that wettability-alterations of the porous medium in contact with the three-phase fluid system and exposure to x-rays can be avoided by using iodine
高电源电压抑制比基准电压源的设计%Design of reference voltage source with high power supply rejection ratio
Institute of Scientific and Technical Information of China (English)
李承蓬; 许维胜; 王翠霞
2014-01-01
在此通过对带隙基准电压源电路进行建模分析，针对逆变电路的中低频使用环境，设计了一个应用于高压逆变器电路中的高电源电压抑制比，低温度系数的带隙基准电压源。该电路采用1μm，700 V高压CMOS工艺，在5 V供电电压的基础上，采用一阶温度补偿，并通过设计高开环增益共源共栅两级放大器来提高电源电压抑制比，同时使用宽幅镜像电流偏置解决因共源共栅引起的输出摆幅变小的问题。基准电压源正常输出电压为2.394 V，温度系数为8 ppm/℃，中低频电压抑制比均可达到-112 dB。%Based on modeling and analysis of the bandgap reference voltage source circuit,a bandgap reference voltage source with high power supply rejection ratio and low temperature coefficient was designed for high-voltage low-frequency inverter circuit. CMOS process of 1 μm and 700 V high-voltage is used in this circuit,which adopts first-order temperature compensa-tion at 5 V voltage. A cascode two-stage amplifier with high open-loop gain was designed to improve the power supply rejection ratio. The wide mirror current bias circuit is used to solve the problem that the output swing becomes smaller due to the cascode circuit. The normal output voltage of the reference voltage source is 2.394 V,its temperature coefficient is 8 ppm/℃,and its low-medium frequency voltage rejection ratio can reach -112 dB.
Institute of Scientific and Technical Information of China (English)
郭艳清; 冯占伟; 袁天驰
2015-01-01
In the voltage type PWM AC/DC/AC conversion , the DC side energy-storage filtering capacitor′s parame-ter selection is one of the key factors for stable operation of the converter .In view of the certain inaccuracy in the DC capacitor′s selection , this paper analyzed the principle of the DC side capacitor′s charge and discharge when the AC/DC/AC conversion circuit in steady state , and studied the voltage relationship between the DC side and the AC side of the converter .A mathematical model between capacitor ripple voltage and three-phase power supply voltage deviation is established .Thus, the capacitance parameter selection method based on the three-phase power supply voltage devi-ation is proposed .This paper respectively gives the appropriate analysis and calculations of filter capacitance when three phase and single phase uncontrolled rectifier circuit provides dc power .And through simulation and experimental verification of the DC filter capacitor energy storage method verifies the validity of arguments .%在电压型PWM AC／DC／AC变换中，直流侧储能滤波电容参数的选取是变换器稳定运行的关键因素之一。针对目前直流侧电容选取存在一定的不精确性，分析了AC／DC／AC变换电路稳态时直流电容充放电的原理，对变换器交直流侧电压的关系进行研究，建立了电容纹波电压与三相供电电压偏差之间的数学模型，提出了基于三相供电电压偏差选取直流侧电容参数的方法。分别对单相和三相不可控整流电路提供直流电源时直流侧电容C的合理选取给出了相应的分析和计算，并通过仿真和试验验证了直流储能滤波电容参数确定方法的有效性。
One-, two- and three-phase viscosity treatments for basaltic lava flows.
Harris, Andrew J L; Allen, John S
2008-01-01
Lava flows comprise three-phase mixtures of melt, crystals, and bubbles. While existing one-phase treatments allow melt phase viscosity to be assessed on the basis of composition, water content, and/or temperature, two-phase treatments constrain the effects of crystallinity or vesicularity on mixture viscosity. However, three-phase treatments, allowing for the effects of coexisting crystallinity and vesicularity, are not well understood. We investigate existing one- and two-phase treatments using lava flow case studies from Mauna Loa (Hawaii) and Mount Etna (Italy) and compare these with a three-phase treatment that has not been applied previously to basaltic mixtures. At Etna, melt viscosities of 425 ± 30 Pa s are expected for well-degassed (0.1 w. % H(2)O), and 135 ± 10 Pa s for less well-degassed (0.4 wt % H(2)O), melt at 1080°C. Application of a three-phase model yields mixture viscosities (45% crystals, 25-35% vesicles) in the range 5600-12,500 Pa s. This compares with a measured value for Etnean lava of 9400 ± 1500 Pa s. At Mauna Loa, the three-phase treatment provides a fit with the full range of field measured viscosities, giving three-phase mixture viscosities, upon eruption, of 110-140 Pa s (5% crystals, no bubble effect due to sheared vesicles) to 850-1400 Pa s (25-30% crystals, 40-60% spherical vesicles). The ability of the three-phase treatment to characterize the full range of melt-crystal-bubble mixture viscosities in both settings indicates the potential of this method in characterizing basaltic lava mixture viscosity.
AC Motor Drive Fed by Renewable Energy Sources with PWM
Directory of Open Access Journals (Sweden)
J. Pavalam
2014-01-01
Full Text Available In this fast aproaching nature of technology the ned of Electricity becomes a mandatory in developing technology. The ned of Electricity increases the power demand where the power demand met by the conventional sources of energy has some disadvantage of polution, this disadvantage can be decreased by the use of the Renewable energy sources like Fuel Cel and available solar energy. When a FUEL cel produces AC power, basicaly two stages are required for conversion first a bosting stage and second is inversion stage. In this paper the Bost inverter topology is achieved where in the conventional methods the normal DC - AC power conversion method is used where as in this paper the PWM based DC - AC inverter has ben used which is useful in reducing the harmonics in the output of the Inverter. The voltage controled output is produced in the bost inverter the curent controled output is taken from dc-dc bidirectional converter. The Fuel cel canot be relied as a whole so a Solar PV module is conected acros the Load so while the Sunlight days the PV arays generate power and in the night time the Fuel cel is used to generate power for the load. Since, the Fuel cel and PV arays can generate power in Partial load they are prefered than any other sources. When the output from the Solar PV aray is low or when the sunlight available is not eficient in generating the power a automatic switch over is provided in the junction betwen the Solar PV aray and Fuel cel so that whenever it hapens the switch automaticaly switch over to another source. The simulation results are presented to confirm the operational feature of the proposed system.
High Frequency Soft Switching Of PWM Boost Converter Using Auxiliary Resonant Circuit
Directory of Open Access Journals (Sweden)
C. P. Sai Kiran
2014-10-01
Full Text Available This thesis presents High frequency Soft Switching DC-DC boost Converter. The circuit consists of a general Boost Converter with an additional resonant circuit which has a switch, inductor, capacitor and a diode.In general Boost Converter circuits have snubber circuits where switching losses are dissipated in external passive resistors; which is known as hard switching. As the switching frequency of PWM converters is increased its switching losses and conduction losses also increases. This restricts the use of PWM technique. New Zero Voltage Transition-Zero Current Transition (ZVT-ZCT PWM converter equipped with the snubber provides the most desirable features of both ZVT and ZCT converters presented previously. Moreover all semiconductors devices operate with soft switching and hence losses are reduced.
Design hardware calculator in PWM peripherals of nios Ⅱ with verilog HDL
Institute of Scientific and Technical Information of China (English)
XU Yang; XIANG Min
2009-01-01
The Plus Width Module (PWM) in microprocessors is commonly used in motor control field. If the ordinary PWM peripherals output PWM waveform, the software must calculate the period and duty cycle number based on the microprocessor's system clock cycle first, and then write them into the registers. As all known, the microprocessor without hardware calculator consume very long time in multiplication and division. In order to reduce the CPU's running time, a calculation hardware unit was designed to calculate the waveform parameters. The software only need to write the period (Hz units) to the period register and the duty cycle (% units)to its register. This hardware unit was designed with Verilog HDL and running in the Nios II system successfully.
EVALUATION OF VARIOUS UNIPOLAR MULTICARRIER PWM STRATEGIES FOR FIVE LEVEL FLYING CAPACITOR INVERTER
Directory of Open Access Journals (Sweden)
B. SHANTHI
2012-06-01
Full Text Available This paper presents the comparison of unipolar multicarrier Pulse Width Modulation (PWM techniques for the Flying Capacitor Multi Level Inverter (FCMLI. Due to switch combination redundancies, there are certain degrees of freedom to generate the five level AC output voltage. This paper presents the use of Control Freedom Degree (CFD combination. The effectiveness of the PWM strategies developed using CFD are demonstrated by simulation and experimentation. The results indicate that the multilevel inverter triggered by the developed USHPWM strategy exhibits reduced harmonics. PWM strategies developed are implemented in real time using dSPACE/Real Time Interface (RTI. The simulation and experimental output closely match with each other validating the strategies presented.
Isolated PDM and PWM DC-AC SICAMs[Pulse Density Modulated; Pulse Width Modulated
Energy Technology Data Exchange (ETDEWEB)
Ljusev, P.
2004-03-15
In this report a class of isolated PDM and PWM DC-AC SICAMs is described, which introduce the audio reference only in the output stage. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitor. Isolation from the AC mains is achieved using a high frequency (HF) transformer, receiving the HF voltage pulses from the input 'inverter' stage and transferring them to the output 'rectifier+inverter' stage, which can use either PDM or PWM. The latter stage is then interfaced to the load using an output low-pass filter. Each of the dedicated stages is discussed in detail. Measurements on the master/slave PWM DC-AC SICAM prototype are presented to help benchmarking the performance of this class of SICAMs and identify the advantages and drawbacks. (au)
DEFF Research Database (Denmark)
Zhang, Gang; Yang, Yongheng; Iannuzzo, Francesco
2016-01-01
of the 3L-ANPC topology. This paper presents a novel loss balancing modulation strategy - Splitting Switching Loss Distribution PWM (SSLD-PWM) strategy to achieve more even loss distribution in the 3L-ANPC converter. Basically, in the proposed PWM strategy, the switching-on losses and switching-off losses...
Energy Technology Data Exchange (ETDEWEB)
Garza Macias, Anibal [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)
1988-12-31
In the Mexico`s Gulf Coast and in the North East part of the country there are severe pollution problems on the electric distribution power systems insulators. To solve this problem, in specialized laboratories are reproduced the pollution conditions for their quantitative and qualitative analyses. In general terms, for this purpose special voltage transformers have been used that, for being imported, are very expensive; furthermore there is no defined selection criterion that allows the voltage source to supply the current recommended by the IEC (International Electrotechnical Commission). In this article, a proposal is presented to select a transformer that fulfills the IEC requirements. This equipment, because of its acquisition easiness and economy, permits that any teaching or research institution have a voltage source that allows the experimentation of the pollution phenomena at a minimum cost. [Espanol] En la costa del Golfo de Mexico y en el noroeste del pais hay severos problemas de contaminacion en los aisladores de los sistemas electricos de distribucion. Para solucionar este problema, se reproducen, en laboratorios especializados, las condiciones de contaminacion para su analisis cualitativo y cuantitativo. En general, con este proposito se han utilizado transformadores especiales de voltaje que por ser de importacion son muy costosos; ademas, no existe un criterio definido de seleccion que permita suministrar a la fuente de voltaje la corriente recomendada por el IEC (International Electrotechnical Commission). En este articulo se presenta una propuesta para seleccionar un transformador que cumpla con los requerimientos del IEC. Esta, por su facilidad de adquisicion y economia, permite que cualquier institucion docente o de investigacion cuente con una fuente de voltaje que permita la experimentacion de los fenomenos contaminantes con un costo minimo.
Energy Technology Data Exchange (ETDEWEB)
Boehm, Christine
2015-01-14
Atomic masses and hence binding energies of nuclides are of great importance for studies of nuclear structure since they reflect all effective interactions in a nucleus. Within this thesis the masses of seven nuclides, namely {sup 194}Au, {sup 194}Hg, {sup 190,193,198}Tl and {sup 202,208}Pb, were determined at the Penning-trap mass spectrometer ISOLTRAP at ISOLDE/CERN. The thallium region in the chart of isotopes is of special interest due to the occurrence of nuclear structure effects like low-lying isomers, level inversion, shape coexistence and deformations. These effects are investigated by applying finite-difference mass formulas, such as the two-neutron separation energies or the so-called empirical pairing gaps. The second topic addressed within the present thesis is an ultra-stable voltage source, called StaReP (Stable Reference for Penning Trap Experiments), which was developed at the Max-Planck-Institut fuer Kernphysik. It is one of the key components of the high-precision mass spectrometer PENTATRAP, containing a tower of five Penning traps. A 25-channel voltage source with a relative stability of few 10{sup -8} over a period of 10 minutes in the range of 0 to -100V is mandatory for PENTATRAP aiming for mass measurements with relative mass uncertainties of ≤ 10{sup -11}. Mass values with such a high precision allow for stringent tests of quantum electrodynamics in strong electric fields, testing Einstein's mass-energy relation E = mc{sup 2} as well as measurements of decay energies (Q-values) with applications in neutrino physics.
Inflow performance relationship curves in two-phase and three-phase flow conditions
Energy Technology Data Exchange (ETDEWEB)
Sukarno, P.
1986-01-01
This research investigates inflow performance relationship IPR curves for two and three-phase flow conditions, using a one-dimensional, three-phase cylindrical reservoir simulator. Using the simulator, a new method for predicting future IPR curves was developed. IPR curves for two-phase flow conditions from a well producing from low permeability formations are also presented. The purpose of this investigation is to predict the IPR curves at pseudo-steady state conditions using flowing test data obtained during the transient period. The new equations have also been applied to data from the simulator with good agreement. Three-phase IPR curves are also determined by using the simulator, and seven different hypothetical three-phase reservoir cases were studied. Three-hundred and eighty five data points were collected using 5 different values of water cut. Regression analysis techniques were applied to the data points and the new equations for predicting the three-phase IPR curves were developed. Comparison of the new equations to results from the simulator show excellent agreement.
Compositional modeling of three-phase flow with gravity using higher-order finite element methods
Moortgat, Joachim
2011-05-11
A wide range of applications in subsurface flow involve water, a nonaqueous phase liquid (NAPL) or oil, and a gas phase, such as air or CO2. The numerical simulation of such processes is computationally challenging and requires accurate compositional modeling of three-phase flow in porous media. In this work, we simulate for the first time three-phase compositional flow using higher-order finite element methods. Gravity poses complications in modeling multiphase processes because it drives countercurrent flow among phases. To resolve this issue, we propose a new method for the upwinding of three-phase mobilities. Numerical examples, related to enhanced oil recovery and carbon sequestration, are presented to illustrate the capabilities of the proposed algorithm. We pay special attention to challenges associated with gravitational instabilities and take into account compressibility and various phase behavior effects, including swelling, viscosity changes, and vaporization. We find that the proposed higher-order method can capture sharp solution discontinuities, yielding accurate predictions of phase boundaries arising in computational three-phase flow. This work sets the stage for a broad extension of the higher-order methods for numerical simulation of three-phase flow for complex geometries and processes.
Compositional modeling of three-phase flow with gravity using higher-order finite element methods
Moortgat, Joachim; Sun, Shuyu; Firoozabadi, Abbas
2011-05-01
A wide range of applications in subsurface flow involve water, a nonaqueous phase liquid (NAPL) or oil, and a gas phase, such as air or CO2. The numerical simulation of such processes is computationally challenging and requires accurate compositional modeling of three-phase flow in porous media. In this work, we simulate for the first time three-phase compositional flow using higher-order finite element methods. Gravity poses complications in modeling multiphase processes because it drives countercurrent flow among phases. To resolve this issue, we propose a new method for the upwinding of three-phase mobilities. Numerical examples, related to enhanced oil recovery and carbon sequestration, are presented to illustrate the capabilities of the proposed algorithm. We pay special attention to challenges associated with gravitational instabilities and take into account compressibility and various phase behavior effects, including swelling, viscosity changes, and vaporization. We find that the proposed higher-order method can capture sharp solution discontinuities, yielding accurate predictions of phase boundaries arising in computational three-phase flow. This work sets the stage for a broad extension of the higher-order methods for numerical simulation of three-phase flow for complex geometries and processes.
PID Controller Design for UPS Three-Phase Inverters Considering Magnetic Coupling
Directory of Open Access Journals (Sweden)
Yu Zhang
2014-11-01
Full Text Available In three-phase inverters used in uninterruptible power supplies (UPSs, three-limb inductors and three-limb transformers are commonly used in consideration of cost and size. However, magnetic coupling exists between the three phases of the inverter, which can result in complex models. When instantaneous feedback control strategies are introduced to achieve high quality output waveforms, the transient analysis of the closed-loop inverters becomes difficult. In this paper, the phenomenon of magnetic coupling in three-phase inverters due to three-limb inductors and three-limb transformers is analyzed. A decoupled dynamic model is derived based on the instantaneous symmetrical components transformation, which comprises three decoupled equivalent circuits of instantaneous symmetrical components. Analyses based on this model indicate that magnetic coupling may have a significant impact on the performance of three-phase inverters under unbalanced load conditions and transient responses. For three-phase inverters in UPSs with Proportional-Integral-Differential (PID closed-loop control strategies, the interactive influence between instantaneous closed-loop regulation and magnetic coupling is researched. Finally, a method of reliability analysis and PID controller design for inverters with magnetic coupling is derived. Simulation and experiment results validate the model and conclusions.
Led spectral and power characteristics under hybrid PWM/AM dimming strategy
DEFF Research Database (Denmark)
Beczkowski, Szymon; Munk-Nielsen, Stig
2010-01-01
In order to dim LEDs the pulse width modulation (PWM) or amplitude modulation (AM) dimming scheme is typically used. Previous studies show that these dimming schemes can have opposite effects on diodes peak wavelength shift. An experimental study was conducted to test the behavior of InGaN diodes...... and phosphor-converted white diodes under hybrid PWM/AM modulation. Feed forward control schemes that provide stable peak wavelength position during dimming and the ability to compensate the thermally induced color shifts and the decrease of the luminous flux are investigated....
Performance Comparison of Phase Shifted PWM and Sorting Method for Modular Multilevel Converters
DEFF Research Database (Denmark)
Haddioui, Marcos Rejas; Máthé, Lászlo; Burlacu, Paul Dan;
2015-01-01
Modular Multilevel Converters (MMC) are the solution of preference in HVDC applications due to modularity, scalability, low losses and low filtering requirement. Carrier-based (PWM) and carrier-less (nearest level control) modulation can be applied. By using advanced sorting methods focusing...... on keeping the capacitor voltage ripple under some limit, unnecessary switching events are eliminated leading to reduced switching losses. This paper presents a comparison between the steady-state performances in terms of output voltage THD and equivalent switching frequency of the Phase Shifted Carrier PWM...
Soft Switching Full-Bridge PWM DC/DC Converter Using Secondary Snubber
Directory of Open Access Journals (Sweden)
Jaroslav Dudrik
2009-05-01
Full Text Available A novel full-bridge PWM DC/DCconverter with controlled secondary side rectifier usingsecondary snubber is presented in this paper.Limitation of the circulating current as well as softswitching for all power switches of the inverter isachieved for full load range from no-load to shortcircuit by using controlled rectifier and snubber on thesecondary side. Phase shift PWM control strategy isused for the converter. The principle of operation isexplained and analyzed and the experimental resultson a 1kW, 50 kHz laboratory model of the converterare presented.
Elimination of output voltage oscillations in DC-DC converter using PWM with PI controller
Directory of Open Access Journals (Sweden)
Sreenivasappa Veeranna Bhupasandra
2010-01-01
Full Text Available In this paper the SIMULINK model of a PWM controlled DC-DC converter is modeled using switching function concept to control the speed of the DC motor. The presence of the voltage oscillation cycles due to higher switching frequency in the DC-DC converter is identified. The effect of these oscillations on the output voltage of the converter, Armature current, Developed torque and Speed of the DC motor is analyzed. In order to minimize the oscillation cycles the PI controller is proposed in the PWM controller.
Directory of Open Access Journals (Sweden)
Olivier Barre
2015-06-01
Full Text Available Mutual inductance is a phenomenon caused by the circulation of the magnetic flux in the core of an electrical machine. It is the result of the effect of the current flowing in one phase on the other phases. In conventional three-phase machines, such an effect has no influence on the electrical behaviour of the device. Although these machines are powered by power inverters, no problem should occur. The result is not the same for multi-star machines. If these machines are using a conventional winding structure, namely distributed windings, and are powered by voltage source converters, current ripples appear in the power supply lines. These current ripples are related to magnetic couplings between the stars. Designers should check these current ripples in order to stay within the limits imposed by the specifications. These electric current disturbances also provide torque ripples. With concentrated windings, a new degree of freedom appears; the configuration—number of slots/number of poles—can have a positive impact. The circulation of the magnetic flux is the initial phenomenon that produces the mutual inductance. The main goal of this discussion is to describe a design method that is able to produce not only a machine with low mutual inductance between phases, but also a multi-star machine where the stars and the phases are magnetically decoupled or less coupled. This discussion only takes into account the machines that use permanent magnets mounted on the rotor surface. This article is part of a study aimed at designing a high efficiency generator using fractional-slot concentrated-windings (FSCW.
Fuzzy-Expert Diagnostics for Detecting and Locating Internal Faults in Three Phase Induction Motors
Institute of Scientific and Technical Information of China (English)
DONG Mingchui; CHEANG Takson; SEKAR Booma Devi; CHAN Sileong
2008-01-01
Internal faults in three phase induction motors can result in serious performance degradation and eventual system failures if not properly detected and treated in time. Artificial intelligence techniques, the core of soft-computing, have numerous advantages over conventional fault diagnostic approaches; therefore, a soft-computing system was developed to detect and diagnose electric motor faults. The fault diagnostic system for three-phase induction motors samples the fault symptoms and then uses a fuzzy-expert forward inference model to identify the fault. This paper describes how to define the membership functions and fuzzy sets based on the fault symptoms and how to construct the hierarchical fuzzy inference nets with the propagation of probabilities concerning the uncertainty of faults. The designed hierarchical fuzzy inference nets efficiently detect and diagnose the fault type and exact location in a three phase induction motor. The validity and effectiveness of this approach is clearly shown from obtained testing results.
A Novel Unit Power Factor Rectifier Based on Three-phase Digital PLL
Directory of Open Access Journals (Sweden)
Xuegui Zhu
2013-07-01
Full Text Available A novel three-phase phase-locked loop solution is proposed based on D-Q transformation aiming at the AC-DC rectifier with high efficiency and high power factor. The phase-locked loop is implemented digitally using the Xilinx blockset integrated with Matlab/Simulink. The three-phase digital phase-locked loop (TDPLL is elaborately designed with the parameters defined in detail. The AC-DC converter (rectifier model with the TDPLL is built and simulated in the high-speed VHS-ADC simulation platform from Canada. The simulation and test results show the TDPLL is locked right after the different three-phase voltage disturbances and very suitable for control of the rectifier with high parallelism through space vector pulse width modulation (SVPWM.
Kolla, Sri R; Altman, Shawn D
2007-04-01
This paper presents results from the implementation and testing of a PC based monitoring and fault identification scheme for a three-phase induction motor using artificial neural networks (ANNs). To accomplish the task, a hardware system is designed and built to acquire three-phase voltages and currents from a 1/3 HP squirrel-cage, three-phase induction motor. A software program is written to read the voltages and currents, which are first used to train a feed-forward neural network structure using the JavaNNS program. The trained network is placed in a LabVIEW based program formula node that monitors the voltages and currents online and displays the fault conditions and turns the motor off. The complete system is successfully tested in real time by creating different faults on the motor.
Phase field modeling and simulation of three-phase flow on solid surfaces
Zhang, Qian; Wang, Xiao-Ping
2016-08-01
Phase field models are widely used to describe the two-phase system. The evolution of the phase field variables is usually driven by the gradient flow of a total free energy functional. The generalization of the approach to an N phase (N ≥ 3) system requires some extra consistency conditions on the free energy functional in order for the model to give physically relevant results. A projection approach is proposed for the derivation of a consistent free energy functional for the three-phase Cahn-Hilliard equations. The system is then coupled with the Navier-Stokes equations to describe the three-phase flow on solid surfaces with moving contact line. An energy stable scheme is developed for the three-phase flow system. The discrete energy law of the numerical scheme is proved which ensures the stability of the scheme. We also show some numerical results for the dynamics of triple junctions and four phase contact lines.
High Efficiency Three-phase Power Factor Correction Rectifier using Wide Band-Gap Devices
DEFF Research Database (Denmark)
Kouchaki, Alireza
2016-01-01
Improving the conversion efficiency of power factor correction (PFC) rectifiers has become compelling due to their wide applications such as adjustable speed drives, uninterruptible power supplies (UPS), and battery chargers for electric vehicles (EVs). The attention to PFCs has increased even more...... design that has lower parasitic elements. To fulfill the grid regulations (e.g. IEEE-519) high order filters are normally used. Achieving an optimum filter design is vital for having an efficient converter. Reducing low frequency harmonics can improve both the efficiency and also the power quality...... hardware design using WBG devices to improve the conversion efficiency and 2) Identifying the impact on the efficiency by current controller. Part 1 is presented in Chapter 3. The converter topology is a two-level bidirectional boost voltage source converter (VSC). SiC devices (i.e. MOSFET and diode...
Power quality improvement using DPC controlled three-phase shunt active filter
Energy Technology Data Exchange (ETDEWEB)
Chaoui, Abdelmadjid [Laboratoire d' Automatique et d' Informatique Industrielle (LAII-ESIP), Universite de Poitiers (France); Gaubert, Jean-Paul; Krim, Fateh [Laboratoire d' Electronique de Puissance et Commande Industrielle (LEPCI), Universite de Setif (Algeria)
2010-06-15
This paper presents a new control method entitled direct power control (DPC) for shunt active power filter (APF), which is applied to eliminate line current harmonics and compensate reactive power. Its main goal is to rebuild active and reactive source powers to be compared to references values using hysteresis control. The active power reference is issue of DC-side of inverter and reactive power reference is set to zero for unity power factor. The outputs of hysteresis controllers associated with a switching table, control the instantaneous active and reactive power by selecting the optimum switching state of the voltage source inverter (VSI). A theoretical analysis with a complete simulation of the system and experimental results are presented to prove the excellent performance of the proposed technique. (author)
Institute of Scientific and Technical Information of China (English)
宋平岗; 王锴; 兰洁; 李澄
2014-01-01
In this paper, the direct power control (DPC ) is applied to a three-phase grid-connected photovoltaic system to analyze the PV characteristics, establish voltage PWM Rectifier mathematical mode, and study the principle of the DPC system. By the analysis of the deficiencies of the traditional switching table, the paper also proposes a new switching table. Using Matlab / Simulink simulation to compare the performance of the three-phase photovoltaic grid-based the traditional switching table DPC with new switching table DPC, the results show thatthe performance of the three-phase photovoltaic grid system can be improved based on new switching table DPC, it has a certain significance for photovoltaic system.%将直接功率控制（DPC）应用于三相光伏并网系统中，分析了光伏特性，建立了电压型PWM整流器的数学建模，研究了DPC系统的原理，通过分析传统开关表的不足，提出了一种新型的开关表。利用Matlab/Simulink仿真，比较了基于传统开关表的DPC与基于新型开关表的DPC在三相光伏并网中的性能。结果表明：基于新型开关表的DPC可以较好的改善三相光伏并网系统的性能，对光伏并网系统具有一定的意义。
Effect of spreading coefficient on three-phase relative permeability of nonaqueous phase liquids
Keller, Arturo A.; Chen, Mingjie
2003-10-01
Three-phase flow conditions are encountered regularly, for example, during migration of released NAPL through the vadose zone, certain stages of soil vapor extraction, bioslurping, or generation of gases by microbes. To model three-phase flow, a common approach is to construct three-phase relative permeabilities based on a combination of two-phase relative permeabilities. Although this circumvents a lack of experimental data, it can lead to serious underprediction or overprediction of residual NAPL saturation. This can mislead decision makers that need to predict whether a particular spill will reach the water table or predict the speed of a NAPL front or conduct an assessment of the performance of remediation actions. Experimental data to estimate three-phase relative permeabilities is sparse. A study by [2000a] generated significant experimental information. Their analysis focused on the high NAPL saturation region, given their emphasis on oil reservoir engineering. For environmental applications the low saturation region is of more interest. Using this data set, we derived a set of empirical relations that relate NAPL three-phase relative permeability krn to NAPL saturation Sn and spreading coefficient Cs for Sn less than about 0.1, such that krn = ? where A1 = 0.012 exp (-1.3Cs) and A2 = 2.1 - 0.60Cs + 0.036Cs2. At higher Sn, krn ≈ Sn4, independent of Cs. We present a pore-scale conceptual model that provides a phenomenological basis for the use of Cs as a predictor of krn at low Sn. We then present a number of simulated case studies that highlight the effect of these three-phase relative permeabilities on risk assessment or remediation design.
Single-phase DECT with VNCT compared with three-phase CTU in patients with haematuria
Energy Technology Data Exchange (ETDEWEB)
Park, Jung Jae; Park, Byung Kwan; Kim, Chan Kyo [Sungkyunkwan University School of Medicine, Department of Radiology, Samsung Medical Center, Seoul (Korea, Republic of)
2016-10-15
To retrospectively evaluate the diagnostic performance of single-phase dual-energy CT (DECT) with virtual non-contrast CT (VNCT) compared with three-phase CT urography (CTU) in patients with haematuria. A total of 296 patients underwent three-phase CTU (NCT at 120 kVp; nephrographic phase and excretory phase DECTs at 140 kVp and 80 kVp) owing to haematuria. Diagnostic performances of CT scans were compared for detecting urothelial tumours and urinary stones. Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU Dose-length product (DLP) was compared in relation to single-phase DECT and three-phase CTU. Sensitivity and specificity for tumour were 95 % (19/20) and 98.9 % (273/276) on CTU, 95 % (19/20) and 98.2 % (271/276) on nephrographic phase DECT, and 90 % (18/20) and 98.2 % (271/276) on excretory phase DECT (P > 0.1). Of the 148 stones detected on NCT, 108 (73 %) and 100 (67.6 %) were detected on nephrographic phase and excretory phase VNCTs, respectively. The mean size of stones undetected on nephrographic and excretory VNCTs was measured as 1.5 ± 0.5 mm and 1.6 ± 0.6 mm, respectively. The mean DLPs of three-phase CTU, nephrographic phase DECT and excretory phase DECT were 1076 ± 248 mGy . cm, 410 ± 98 mGy . cm, and 360 ± 87 mGy . cm, respectively (P < 0.001). Single-phase DECT has a potential to replace three-phase CTU for detecting tumours with a lower radiation dose. (orig.)
Sliding mode control for a three phase multicellular inverter dedicated to renewable energy systems
Hemici, K.; Zegaoui, A.; Djahbar, A.; Bokhtache, A. Aissa; Kessaissia, F. Z.; Allouache, H.; Mahmoudi, M. O.; Aillerie, M.
2017-02-01
In this paper, Sliding Mode controller has been sized to control multi-cell converters configured as a three-phase multicellular inverter. Unlike traditional inverters, multicellular inverters have the following advantages: lower switching frequency, high number of output levels, and less voltage constraints on the power switch. Significant performances are provided with this structure, which is constituted with flying capacitors. The main purpose of this paper is to present the model and generate commutation sliding-surfaces based on a Lyapunov function. The performed simulations point the efficiency of the proposed strategy with a three-phase multicellular inverters and allow to assess the performances and the robustness of the synthesized controller.
Three-Phase Modulated Pole Machine Topologies Utilizing Mutual Flux Paths
DEFF Research Database (Denmark)
Washington, Jamie G.; Atkinson, Glynn J.; Baker, Nick J.
2012-01-01
This paper discusses three-phase topologies for modulated pole machines (MPMs). The authors introduce a new threephase topology, which takes advantage of mutual flux paths; this is analyzed using 3-D finite-element methods and compared to a three-phase topology using three single-phase units...... stacked axially. The results show that the new “combined-phase MPM” exhibits a greater torque density, while offering a reduction in the number of components. The results obtained from two prototypes are also presented to verify the concept; the results show that the “combined-phase” machine could provide...
Novel, Four-Switch, Z-Source Three-Phase Inverter
DEFF Research Database (Denmark)
Antal, Robert; Muntean, Nicolae; Boldea, Ion
2010-01-01
) value as in six switch standard three-phase inverter. The article presents the derivation of the equations describing the operation of the converter based on space vector analysis, validation through digital simulations in PSIM and preliminary experimental results on a laboratory setup with a dsPIC30F......, besides the self-boost property, has low switch count and it can operate as a buck-boost inverter. In contrast to standard four-switch three-phase inverter which operates at half dc input voltage the proposed four-switch z-source inverter, by self boosting, brings the output voltage at same (or higher...
MAGNETIZING CURRENT INRUSH IN THREE PHASE POWER TRANSFORMERS DURING INCOMPLETE PHASE SWITCHING
Directory of Open Access Journals (Sweden)
V. I. Novash
2005-01-01
Full Text Available The paper provides investigation results of magnetizing current inrushes in three-phase transformer during one-phase switching. Numerical experiments have been carried out with the help of a mathematical model developed on the basis of the second dissipation theory. It is shown that a magnetizing current inrush in the phase to be switched with absence of a residual induction exceeds an analogous inrush values by 1.4…1.6-fold in the case of simultaneous switching of all three phases.
Approximate Calculation of Voltage in Three-Phase Primary Distribution Feeder
Iioka, Daisuke; Iwata, Kubou; Kondo, Hisashi; Sakaguchi, Takuma; Shigetou, Takaya; Matsumura, Toshiro
An approximate method to calculate voltage in three-phase primary distribution feeder has been proposed. Generally, nonlinear simultaneous equations have been solved to calculate the voltage in power system since the dependence of electrical equipment on voltage is represented by exponential model such as constant power load, constant current load and constant impedance load. The nonlinear simultaneous equations were transformed to linear simultaneous equations by the proposed method. As a result, the proposed method can calculate the voltage without convergence calculations. It was found that the approximate value of voltage in the three-phase primary distribution feeder is in good agreement with the exact value.
Juvenile Dermatomyositis Diagnosed by {sup 99m}Tc-HDP Three-phase Bone Scintigraphy
Energy Technology Data Exchange (ETDEWEB)
Kim, Ja Hye; Song, Ho Chun; Yoo, Su Ung; Ha, Jung Min; Chong, A Ri; Oh, Jong Ryool; Min, Jung Joon; Bom, Hee Seung; Jeong, Eun Hui; Lee, Min Chul [Chonnam National University Hospital, Gwangju (Korea, Republic of)
2009-12-15
Juvenile dermatomyositis is a common inflammatory muscle disease of childhood, characterized by weakness in proximal muscles and specific skin rash. In case of juvenile dermatomyositis without characteristic clinical features, non-invasive imaging tools such as {sup 99m}Tc-HDP three-phase bone scan are very helpful in diagnostic workup of myopathies. We report a case of 13-year old female with juvenile dermatomyositis, in which {sup 99m}Tc-HDP three-phase bone scan was useful in diagnosis and assessing therapy response.
Area Based Approach for Three Phase Power Quality Assessment in Clarke Plane
Directory of Open Access Journals (Sweden)
S. CHATTOPADHYAY
2008-03-01
Full Text Available This paper presents an area-based approach for electric power quality analysis. Some specific reference signals have been defined and areas formed by the real power system data with the reference signal have been calculated wherefrom contributions of fundamental waveform and harmonic components have been assessed separately. Active power, reactive power and total harmonic distortion factors have been measured. Clarke transformation technique has been used for analysis in three-phase system, which has reduced the computational effort to a great extent. Distortion factors of individual phase of a three-phase system have also been assessed.
A Study of Novel ZVZCT SoftSwitching PWM Boost Converters%新型ZVZCT软开关PWM Boost 变换器的研究
Institute of Scientific and Technical Information of China (English)
林国庆; 张冠生; 陈为; 黄是鹏
2000-01-01
The paper presents a novel ZVZCT softswitching PWM converter:the voltage and current waveforms of the transistor are laddershaped and stagger each other,and auxiliary switches are turned on and off under zero current.It is very attractive for high power application where IGBT is predomi nantly used as the power switches.Theoretical analysis,parameters selection,comp uter simulation,and experiment results are presented to explain the proposed sch eme.
Lee, S. H.; Efendiev, Y.
2016-10-01
Three-phase flow in a reservoir model has been a major challenge in simulation studies due to slowly convergent iterations in Newton solution of nonlinear transport equations. In this paper, we examine the numerical characteristics of three-phase flow and propose a consistent, "C1-continuous discretization" (to be clarified later) of transport equations that ensures a convergent solution in finite difference approximation. First, we examine three-phase relative permeabilities that are critical in solving nonlinear transport equations. Three-phase relative permeabilities are difficult to measure in the laboratory, and they are often correlated with two-phase relative permeabilities (e.g., oil-gas and water-oil systems). Numerical convergence of non-linear transport equations entails that three-phase relative permeability correlations are a monotonically increasing function of the phase saturation and the consistency conditions of phase transitions are satisfied. The Modified Stone's Method II and the Linear Interpolation Method for three-phase relative permeability are closely examined for their mathematical properties. We show that the Linear Interpolation Method yields C1-continuous three-phase relative permeabilities for smooth solutions if the two phase relative permeabilities are monotonic and continuously differentiable. In the second part of the paper, we extend a Hybrid-Upwinding (HU) method of two-phase flow (Lee, Efendiev and Tchelepi, ADWR 82 (2015) 27-38) to three phase flow. In the HU method, the phase flux is divided into two parts based on the driving forces (in general, it can be divided into several parts): viscous and buoyancy. The viscous-driven and buoyancy-driven fluxes are upwinded differently. Specifically, the viscous flux, which is always co-current, is upwinded based on the direction of the total velocity. The pure buoyancy-induced flux is shown to be only dependent on saturation distributions and counter-current. In three-phase flow, the
An Integrated Inductor for Parallel Interleaved VSCs and PWM Schemes for Flux Minimization
DEFF Research Database (Denmark)
Gohil, Ghanshyamsinh Vijaysinh; Bede, Lorand; Teodorescu, Remus;
2015-01-01
The interleaving of the carrier signals of the parallel Voltage Source Converters (VSCs) can reduce the harmonic content in the resultant switched output voltages. As a result, the size of the line filter inductor can be reduced. However, in addition to the line filter, an inductive filter is oft...
Energy Technology Data Exchange (ETDEWEB)
Ramos, Mario Cesar E.S.; Tatizawa, Hedio [Universidade de Sao Paulo (USP), SP (Brazil); Ramos, Mario Cesar Giacco [Universidade de Mogi das Cruzes (UMC), SP (Brazil)
2009-04-15
National and international methodologies are presented existing for determination of the yield of industrial three phase induction motors, viewing the energy consumption reduction and assessment of possible equipment replacement. So, measurement results were analysed, conducted by five enterprises specialized on motor efficiency. Also, it is presented a case study using the described methodologies.
Performance improvement of three phase rectifier by employing electronic smoothing inductor
DEFF Research Database (Denmark)
Singh, Yash Veer; Rasmussen, Peter Omand; Andersen, Torben O.
2014-01-01
An electronic smoothing inductor (ESI) is very attractive circuit topology to improve power factor and to reduce the total harmonic distortions (THDs) of the ac mains current in a three phase diode bridge rectifier. The ESI reduces the low frequency ripples and controls the intermediate dc...
Analysis of Three-Phase Rectifier Systems with Controlled DC-Link Current Under Unbalanced Grids
DEFF Research Database (Denmark)
Kumar, Dinesh; Davari, Pooya; Zare, Firuz
2017-01-01
Voltage unbalance is the most common disturbance in distribution networks, which give undesirable effects on many grid connected power electronics systems including Adjustable Speed Drive (ASD). Severe voltage unbalance can force three-phase rectifiers into almost single-phase operation, which de...
The analysis of magnesium oxide hydration in three-phase reaction system
Tang, Xiaojia; Guo, Lin; Chen, Chen; Liu, Quan; Li, Tie; Zhu, Yimin
2014-05-01
In order to investigate the magnesium oxide hydration process in gas-liquid-solid (three-phase) reaction system, magnesium hydroxide was prepared by magnesium oxide hydration in liquid-solid (two-phase) and three-phase reaction systems. A semi-empirical model and the classical shrinking core model were used to fit the experimental data. The fitting result shows that both models describe well the hydration process of three-phase system, while only the semi-empirical model right for the hydration process of two-phase system. The characterization of the hydration product using X-Ray diffraction (XRD) and scanning electron microscope (SEM) was performed. The XRD and SEM show hydration process in the two-phase system follows common dissolution/precipitation mechanism. While in the three-phase system, the hydration process undergo MgO dissolution, Mg(OH)2 precipitation, Mg(OH)2 peeling off from MgO particle and leaving behind fresh MgO surface.
Analysis of a Three Phase Induction Motor Directly from Maxwell's Equations
Bhattacharjee, Shayak
2011-01-01
The torque developed in a three phase AC squirrel cage motor is usually expressed in terms of resistances and reactances of the stator, the rotor, and the motor as a whole. We use Maxwell's equations to find the torque in terms of geometrical parameters. This allows us to estimate the torque developed by a motor without knowing the details of its circuitry.
Teaching Qualitative Research for Human Services Students: A Three-Phase Model
Goussinsky, Ruhama; Reshef, Arie; Yanay-Ventura, Galit; Yassour-Borochowitz, Dalit
2011-01-01
Qualitative research is an inherent part of the human services profession, since it emphasizes the great and multifaceted complexity characterizing human experience and the sociocultural context in which humans act. In the department of human services at Emek Yezreel College, Israel, we have developed a three-phase model to ensure a relatively…
Optimal Power Flow in three-phase islanded microgrids with inverter interfaced units
DEFF Research Database (Denmark)
Sanseverino, Eleonora Riva; Quang, Ninh Nguyen; Di Silvestre, Maria Luisa
2015-01-01
In this paper, the solution of the Optimal Power Flow (OPF) problem for three phase islanded microgrids is studied, the OPF being one of the core functions of the tertiary regulation level for an AC islanded microgrid with a hierarchical control architecture. The study also aims at evaluating...
Three-phase scintigraphy in epicondylitis of the lateral lower humerus
Energy Technology Data Exchange (ETDEWEB)
Koppers, B.; Riel, K.
1982-08-01
Ten patients with tennis elbow were examined by three-phase scintigraphy, using sup(99m)Tc-MDP. In agreement with the histological findings of H. Schneider (14), there was no uptake during the perfusion and soft tissue phase. In the phase, there was focal bone uptake in one patient only.
Three-phase inductive-coupled structures for contactless PHEV charging system
Lee, Jia-You; Shen, Hung-Yu; Li, Cheng-Bin
2016-07-01
In this article, a new-type three-phase inductive-coupled structure is proposed for the contactless plug-in hybrid electric vehicle (PHEV) charging system regarding with SAE J-1773. Four possible three-phase core structures are presented and subsequently investigated by the finite element analysis. To study the correlation between the core geometric parameter and the coupling coefficient, the magnetic equivalent circuit model of each structure is also established. In accordance with the simulation results, the low reluctance and the sharing of flux path in the core material are achieved by the proposed inductive-coupled structure with an arc-shape and three-phase symmetrical core material. It results in a compensation of the magnetic flux between each phase and a continuous flow of the output power in the inductive-coupled structure. Higher coupling coefficient between inductive-coupled structures is achieved. A comparison of coupling coefficient, mutual inductance, and self-inductance between theoretical and measured results is also performed to verify the proposed model. A 1 kW laboratory scale prototype of the contactless PHEV charging system with the proposed arc-shape three-phase inductive-coupled structure is implemented and tested. An overall system efficiency of 88% is measured when two series lithium iron phosphate battery packs of 25.6 V/8.4 Ah are charged.
A laboratory grid simulator based on three-phase four-leg inverter
DEFF Research Database (Denmark)
Li, Fei; Wang, Xiongfei; Chen, Zhe
2011-01-01
This paper presents the design and implementation of a laboratory grid simulator which is used to test the grid-connected devices according to the strict standards. Three-phase four-leg inverter with direct voltage control in Natural Frame is adopted in this grid simulator, which significantly re...
Morphological modelling of three-phase microstructures of anode layers using SEM images.
Abdallah, Bassam; Willot, François; Jeulin, Dominique
2016-07-01
A general method is proposed to model 3D microstructures representative of three-phases anode layers used in fuel cells. The models are based on SEM images of cells with varying morphologies. The materials are first characterized using three morphological measurements: (cross-)covariances, granulometry and linear erosion. They are measured on segmented SEM images, for each of the three phases. Second, a generic model for three-phases materials is proposed. The model is based on two independent underlying random sets which are otherwise arbitrary. The validity of this model is verified using the cross-covariance functions of the various phases. In a third step, several types of Boolean random sets and plurigaussian models are considered for the unknown underlying random sets. Overall, good agreement is found between the SEM images and three-phases models based on plurigaussian random sets, for all morphological measurements considered in the present work: covariances, granulometry and linear erosion. The spatial distribution and shapes of the phases produced by the plurigaussian model are visually very close to the real material. Furthermore, the proposed models require no numerical optimization and are straightforward to generate using the covariance functions measured on the SEM images.
Comparison of two-phase and three-phase methanol synthesis processes
van de Graaf, G.H; Beenackers, A.A C M
1996-01-01
A comparison is made between the ICI (two-phase) methanol synthesis process and a three-phase slurry process based on a multi-stage agitated reactor. The process calculations are based on a complete reactor system consisting of the reactor itself, a recycling system and a gas-liquid separator. The b
THREE-PHASE ENERGY SUPPLY SYSTEMS SIMULATION FOR THE TOTAL POWER LOSSES COMPONENTS ASSESSMENT
Directory of Open Access Journals (Sweden)
D.V. Tugay
2016-09-01
Full Text Available Purpose. The goal is to optimize a structure of Matlab-model of the three-phase energy supply system with power active filter. The mathematical model that describes the energy supply system modes of operation which contains additional losses is proposed. Methodology. We have applied concepts of the electrical circuits theory, mathematical modeling elements based on linear algebra and vector calculus, mathematical simulation in Matlab package. Results. We have developed two models of three-phase energy supply system. The first one is based on a vector representation, and the second one on the matrix representation of energy processes. Using these models we have solved the problem of maintaining unchanged the average useful power for 279 cases of energy supply system modes of operation. Originality. We have developed methods of mathematical analysis of a three-phase energy supply systems with polyharmonic voltages and currents in the symmetric and asymmetric modes. Practical value. We have created Matlab-model of a three-phase energy supply system with automated calculation of a correction factor. It allows reducing more than one order the time for energy processes elucidation in multiphase systems.
Influences of Medium Structure of Three-Phase Seabed Deposit on Sound Velocity
Institute of Scientific and Technical Information of China (English)
徐长节; 蔡袁强
2001-01-01
Based on the former research, the mechanism of the influence of the medium structure on the sound velocity of the three- phase seabed deposit is discussed by theoretical method. Through analysis of several structure models of three-phase seabed deposit, an equation of sound velocity is presented, which can describe the effect of structure of three-phase deposit on its acoustic velocity. Seen form the derived equation, the equations of the sound velocity of the deposits with different medium structures are different, the influence of the medium structure on the sound velocity is apparent. The equation in the paper provides the theoretical basis to understand the mechanics properties through sound velocity test, and it can be easily adopted in engineering. The influences of the parameters of deposits, void ratio, gas concentration and modulus on sound velocity through the deposit are investigated by numerical analysis of the acoustic velocity. Numerical result shows that the sound velocity of three-phase medium is affected by void ratio, gas concentration and body modulus, and the sound velocity generally increases with the gas concentration increasing. The results of the paper can be helpful to the acoustic method.
High Efficiency Three-phase Power Factor Correction Rectifier using Wide Band-Gap Devices
DEFF Research Database (Denmark)
Kouchaki, Alireza
2016-01-01
. Therefore, current controllers are also important to be investigated in this project. In this PhD research work, a comprehensive design of a two-level three-phase PFC rectifier using silicon-carbide (SiC) switches to achieve high efficiency is presented. The work is divided into two main parts: 1) Optimum...
Frequency Adaptive Repetitive Control of Grid-Tied Three-Phase PV iInverters
DEFF Research Database (Denmark)
Zhou, Keliang; Yang, Yongheng; Blaabjerg, Frede
2016-01-01
in the presence of practical time-varying grid frequency. This paper explores frequency adaptive repetitive control strategy for grid-interfaced converters, which employs fractional delay filter to adapt to the change of grid frequency. Case studies with experimental results of three-phase grid-connected...... converter systems are provided to verify the proposed controller....
Secondary Voltage Unbalance Compensation for Three-Phase Four-Wire Islanded Microgrids
DEFF Research Database (Denmark)
Tang, Fen; Zhou, Xiao; Meng, Lexuan;
2014-01-01
This paper proposes a secondary voltage unbalance control approach that compensate voltage unbalances in three-phase four-wire islanded microgrid systems. It is implemented in the secondary control level of the microgrid hierarchical control structure. By sending information through low...
Three-phase diode rectifiers with low harmonics current injection methods
Pejovic, Predrag
2007-01-01
Presents results of numerous research papers in the area of current injection based rectifiers. This book discusses the principles of current injection, followed by an analysis of various magnetic current injection devices. It concludes with a chapter where the results are generalized to three-phase full-bridge thyristor rectifiers.
Design and comparison of three-level three-phase T-source inverters
DEFF Research Database (Denmark)
Shults, T.; Husev, Oleksandr; Blaabjerg, Frede
2015-01-01
This paper presents guidelines for component design of recently proposed topologies of the three-level three-phase T-source inverters. Two different topologies are considered: T-source inverters with discontinuous input current and T-source inverters with continuous input current. Steady state...
Institute of Scientific and Technical Information of China (English)
何秀琼; 黄昆; 于品华; 张超; 谢铿; 李鹏飞; 王娟; 安震涛; 刘会洲
2012-01-01
Abstract A new mixer-settler-mixer three chamber integrated extractor is proposed in this work for liquid-liquid- liquid three phase countercurrent and continuous extraction. Experiments revealed the influences of the structural design of the three-liquid-phase extractor and some key operational parameters on three-phase partition of two phenolic isomers, p-nitrophenol （p-NP） and o-nitrophenol （o-NP）. The model three-liquid-phase extraction system used here is nonane （organic top-plaase）-polyethylene glycol （PEG 20UU） （polymer mlddle-phase）-（NH4）2SO4 aqueous solution （aqueous bottom-phase）. It is indicated that agitating speed and retention time in three-phase mixer are key parameters to extraction fraction of nitrophenol. Dispersion band behavior is related to agitating intensity, and its occurrence does not affect the extraction fraction of target compounds. The present work highlights the possibility of a feasible approach of scaling up of the proposed three-phase extraction apparatus for future in- dustrial-aimed applications.
Voltage unbalance mitigation in LV networks using three-phase PV systems
DEFF Research Database (Denmark)
Garcia Bajo, Cristina; Hashemi Toghroljerdi, Seyedmostafa; Bækhøj Kjær, Søren;
2015-01-01
In this paper a new method is proposed to mitigate voltage unbalance caused by single-phase solar inverters in low voltage (LV) networks. The method is based on uneven reactive power absorption and injection by three-phase solar inverters. Independent control of each phase is performed to achieve...
Active and reactive power control of a current-source PWM-rectifier using space vectors
Energy Technology Data Exchange (ETDEWEB)
Salo, M.; Tuusa, H. [Tampere University of Technology (Finland). Department of Electrical Engineering, Power Electronics
1997-12-31
In this paper the current-source PWM-rectifier with active and reactive power control is presented. The control system is realized using space vector methods. Also, compensation of the reactive power drawn by the line filter is discussed. Some simulation results are shown. (orig.) 8 refs.
New PWM method and commutation strategy for HF-link converters for fuel cells and photovoltaics
DEFF Research Database (Denmark)
Ljusev, Petar; Andersen, Michael Andreas E.
2005-01-01
This paper presents a new PWM method and commutation strategy for HF-link converters, which leads to safe commutation of the load current in the output bidirectional bridge. The proposed implementation is independent of the particular HF-link converter topology and bidirectional switch selection...
Six-Phase Vehicular Drive with Renewable DC Sources and Hybrid PWM Control of Four Inverters
DEFF Research Database (Denmark)
Oleschuk, Valentin; Ermuratskii, Vladimir; Blaabjerg, Frede
2015-01-01
The paper presents results of research of quad-inverter-based automotive system with combined scheme of PWM control of inverters, supplied by two renewable dc sources (by fuel cells and by battery). It has been shown, that hybrid switching techniques can be used successfully for control of vehicle...
PWM Flow Rate Control of ER Valve and its Application to ER Actuator Control
Nakano, Masami; Minagawa, Shuji; Hagino, Katsuya
The PWM (Pulse Width Modulation) control of ER valve consisting of two parallel electrodes has been investigated to continuously control the flow rate of an electrorheological (ER) suspension containing sulfonated polymer particles in silicone oil. PWM wave voltages are applied to the electrodes of the ER valve. It is possible to control continuously the flow rate by changing the duty ratio of the PWM wave from 1 to 0, where the duty ratio of 1 corresponds to the state to stop the flow. A miniature bellows actuator driven by a pair of PWM controlled ER valves has been developed, and the control characteristics of the actuator have been investigated. The duty ratios of both ER valves have been proposed to be changed alternately in proportion to the control voltage V to control the flow rate into and out of the bellows chamber, and also an overlap duty ratio Dov at V=0V has been introduced. The introduction of the overlap duty ratio Dov was found to be very important to smoothly control the actuator and to improve the control performance.
DEFF Research Database (Denmark)
Mathe, Laszlo; Cornean, Horia; Sera, Dezso
2011-01-01
of the transfer ratio. The difference between most of the proposed modulation methods like sine-triangular, SVM, and 120 - 60 - 30 Discontinuous PWM consists in the redistribution of the time-length applied for the zero voltage vectors during a fundamental frequency period. This paper presents a unified...
The efficiency of three-level Active NPC converter for different PWM strategies
DEFF Research Database (Denmark)
Floricau, D.; Gateau, G.; Leredde, A.;
2009-01-01
The efficiency of power conversion is an important factor to design static converters. The paper is focused on the calculus of total losses of 3L-NPC and 3L-Active-NPC converters for different PWM strategies. The calculus was made in the most critical operating points when certain switches have...
Realization of PWM Velocity Modulation in Hydraulic Elevator%PWM调速在液压电梯中的实现
Institute of Scientific and Technical Information of China (English)
唐国兴; 恽源世; 徐鸣谦
2001-01-01
This paper introduces the realization of velocity modulation control in hydraulic elevator by using PWM technology. It mainly includes two parts, one is about how to send out PWM signal via computer to perform the velocity modulation, and the other is about the design of manual PWM velocity modulation device.%介绍了运用PWM技术实现液压电梯的调速控制，主要包括两部分，一是用工控机发送PWM信号进行调速，二是手动PWM调速装置的设计。
Calderone, Luigi; Pinola, Licia; Varoli, Vincenzo
1992-04-01
The paper describes an analytical procedure to optimize the feed-forward compensation for any PWM dc/dc converters. The aims of achieving zero dc audiosusceptibility was found to be possible for the buck, buck-boost, Cuk, and SEPIC cells; for the boost converter, however, only nonoptimal compensation is feasible. Rules for the design of PWM controllers and procedures for the evaluation of the hardware-introduced errors are discussed. A PWM controller implementing the optimal feed-forward compensation for buck-boost, Cuk, and SEPIC cells is described and fully experimentally characterized.
Salehifar, Mehdi; Moreno-Equilaz, Manuel
2016-01-01
Due to its fault tolerance, a multiphase brushless direct current (BLDC) motor can meet high reliability demand for application in electric vehicles. The voltage-source inverter (VSI) supplying the motor is subjected to open circuit faults. Therefore, it is necessary to design a fault-tolerant (FT) control algorithm with an embedded fault diagnosis (FD) block. In this paper, finite control set-model predictive control (FCS-MPC) is developed to implement the fault-tolerant control algorithm of a five-phase BLDC motor. The developed control method is fast, simple, and flexible. A FD method based on available information from the control block is proposed; this method is simple, robust to common transients in motor and able to localize multiple open circuit faults. The proposed FD and FT control algorithm are embedded in a five-phase BLDC motor drive. In order to validate the theory presented, simulation and experimental results are conducted on a five-phase two-level VSI supplying a five-phase BLDC motor.
Directory of Open Access Journals (Sweden)
Bharati Raja
2012-12-01
Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-Δ induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.
Energy Technology Data Exchange (ETDEWEB)
Barbosa, Peter Mantovanelli
1993-10-01
This work introduces a new power supply by PWM, operating at constant frequency, with soft communication. The new topology uses only two active switches and absorbs the transformer leakage inductance. Besides, the soft communication takes place with no conduction loss penalty, in comparison with conventional hard switch PWM converters. Principle of operation, analysis, design and experimentation results taken from laboratory prototype rated at 400 W/48 v, 40 Khz, using IGBT are presented. (author) 10 refs., 71 figs.
Dynamic\tmodelling of catalytic three-phase reactors for hydrogenation and oxidation processes
Directory of Open Access Journals (Sweden)
Salmi T.
2000-01-01
Full Text Available The dynamic modelling principles for typical catalytic three-phase reactors, batch autoclaves and fixed (trickle beds were described. The models consist of balance equations for the catalyst particles as well as for the bulk phases of gas and liquid. Rate equations, transport models and mass balances were coupled to generalized heterogeneous models which were solved with respect to time and space with algorithms suitable for stiff differential equations. The aspects of numerical solution strategies were discussed and the procedure was illustrated with three case studies: hydrogenation of aromatics, hydrogenation of aldehydes and oxidation of ferrosulphate. The case studies revealed the importance of mass transfer resistance inside the catalyst pallets as well as the dynamics of the different phases being present in the reactor. Reliable three-phase reactor simulation and scale-up should be based on dynamic heterogeneous models.
CHROMIUM EXTRACTION BY MICROEMULSIONS IN TWO- AND THREE-PHASE SYSTEMS
Directory of Open Access Journals (Sweden)
K. R. O. Melo
2015-12-01
Full Text Available Abstract Microemulsion systems were used to remove chromium from an aqueous solution obtained from acid digestion of tannery sludge. The systems were composed by: coconut oil soap as surfactant, 1-butanol as cosurfactant, kerosene as the oil phase, and chromium solution as the aqueous phase. Two- and three-phase microemulsion extraction methods were investigated in the experiments. Viscosity, effective diameter of the droplets, and extraction and re-extraction efficiencies were evaluated for each system. Two- and three-phase systems showed small variations in droplet diameter, which can be attributed to the formation of micellar structures. Chromium recovery efficiencies for the studied systems were over 96%. The re-extraction step showed that the stripping solution used can release more than 96% of the chromium from the microemulsion phase. Experimental results confirm that chromium can be recovered efficiently using microemulsion systems.
Axial dispersion of the liquid phase in a three-phase Karr reciprocating plate column
Directory of Open Access Journals (Sweden)
DEJAN U. SKALA
2004-07-01
Full Text Available The influence of the gas flow rate and vibration intensity in the presence of the solid phase (polypropylene spheres on axial mixing of the liquid phase in a three phase (gas-liquid-solid Karr reciprocating plate column (RPC was investigated. Assuming that the dispersion model of liquid flow could be used for the real situation inside the column, the dispersion coefficient of the liquid phase was determined as a function of different operating parameters. For a two-phase liquid-solid RPC the following correlation was derived: DL = 1.26(Af1.42 UL0.51 eS0.23 and a similar equation could be applied with ± 30 % confidence for the calculation of axial dispersion in the case of a three-phase RPC: DL = 1.30(Af0.47 UL0.42 UG0.03eS-0.23.
Institute of Scientific and Technical Information of China (English)
Ibrahim A. Abbas
2015-01-01
The present work is concerned with the solution of a problem on thermoelastic interactions in a functional graded material due to thermal shock in the context of the fractional order three-phase lag model. The governing equations of fractional order generalized thermoelasticity with three-phase lag model for functionally graded materials (FGM) (i.e., material with spatially varying material properties) are established. The analytical solution in the transform domain is obtained by using the eigenvalue approach. The inversion of Laplace transform is done numerically. The graphical results indicate that the fractional parameter has significant effects on all the physical quantities. Thus, we can consider the theory of fractional order generalized thermoelasticity an improvement on studying elastic materials.
Existence of three-phase interlines on a cerium dioxide surface
Osarinmwian, Charles
2013-01-01
The three-phase interline described by a statistical continuum limit (i.e. quasi-boundary) has been postulated to gain a deeper insight into the reduction of CeO2 to CeO1.940 in a LiCl-KCl eutectic melt. Fabrication of a CeO2 superstructure by a condensed-phase method provided a CeO2 (111) surface at the nanoscale, which allowed the three-phase interline to be identified given previously reported quantum confinement effects in quasi-stoichiometric CeO2 nanoparticles. Also, the CeO2 superstructure displays the same crystal lattice planes as a bulk CeO2 grain but the triply degenerate Raman-active peak of the grain is higher by a factor of ~ 2.5 with a wider full width at half maximum.
You, Hong; Luo, Wei-nan; Yao, Jie; Chen, Ping; Cai, Wei-min
2005-01-01
A novel three-phase internal circulating fluidized bed photocatalytic reactor was established and the radiation transformation in which was investigated. The experimental results indicate that with the interaction of gas and solid (gas flux > 0.3m3/h), the radiation transformation in the reactor along radial direction conforms to a definite exponential function, which agrees to formula Rose about the rules of light intensity distribution through evenly suspended particles. The value of radiation energy is affected by the initial light intensity, the concentration of photocatalyst and the thickness of liquid layer. The aerated gas amount only influence the state of the fluidized bed and has little effect on the distribution of light intensity along radical direction. Photocatalytic degradation of Rhodamine B indicate that the efficiency of three-phase internal circulating fluidized bed is much higher than slurry bed. The optimal catalyst concentration of this system is 10 - 12g/L.
A Smart Current Modulation Scheme for Harmonic Reduction in Three- Phase Motor Drive Applications
DEFF Research Database (Denmark)
Davari, Pooya; Zare, Firuz; Blaabjerg, Frede
2015-01-01
harmonic mitigation methods have been developed over the years, the total cost and complexity has become the main obstacle in employing prior-art methods for motor drive systems. This paper presents a novel current modulation method based on the electronic inductor concept for three-phase ac-dc systems......Electric motor-driven systems consume considerable amount of the global electricity. Majority of three-phase motor drives are equipped with conventional diode rectifier and passive harmonic mitigation, being witnessed as the main source in generating input current harmonics. While many active...... to reduce input current harmonics. The obtained results at simulation and experimental levels confirm the effectiveness of the proposed approach....
Neural network controlled three-phase four-wire shunt active power filter
Energy Technology Data Exchange (ETDEWEB)
Elmitwally, A.; Abdelkader, S. [Mansura University (Egypt); El-Kateb, M. [Bath University (United Kingdom). Dept. of Electronic and Electrical Engineering
2000-03-01
A three-phase four-wire shunt active power filter for harmonic mitigation and reactive power compensation in power systems supplying nonlinear loads is presented. Three adaptive linear neurons are used to tackle the desired three-phase filter current templates. Another feedforward three layer neural network is adopted to control the output filter compensating currents online. This is accomplished by producing the appropriate switching patterns of the converter's legs IGBTs. Adequate tracking of the filter current references is obtained by this method. The active filter inject the current required to compensate for the harmonic and reactive components of the line currents. Simulation results of the proposed active filter indicate a remarkable improvement in the source current waveforms. This is reflected in the enhancement of the unified power quality index defined. Also, the filter has exhibited quite a high dynamic response for step variations in the load current assuring its potential for real-time applications. (author)
A Novel Harmonic Elimination Approach in Three-Phase Multi-Motor Drives
DEFF Research Database (Denmark)
Davari, Pooya; Yang, Yongheng; Zare, Firuz;
2015-01-01
industrial drives are still equipped with three-phase diode rectifiers. Thus, it is difficult to implement the prior-art harmonic control strategies for active front-ends. Moreover, the total cost and complexity has become an obstacle for these harmonic elimination approaches in multiple drive systems...... results have validated the effectiveness of the proposed approach in terms of harmonic elimination in three-phase multi-drive systems....... and may cause unnecessary losses in power system transformers. Both degradations are apt to occur in motor drive applications. As a consequence, it calls for advanced and intelligent control strategies for the power electronics based drive systems like adjustable speed drives in industry. At present, many...
Directory of Open Access Journals (Sweden)
Vrushali M. Kulkarni
2015-06-01
Full Text Available This work reports a novel approach where three phase partitioning (TPP was combined with microwave for extraction of mangiferin from leaves of Mangifera indica. Soxhlet extraction was used as reference method, which yielded 57 mg/g in 5 h. Under optimal conditions such as microwave irradiation time 5 min, ammonium sulphate concentration 40% w/v, power 272 W, solute to solvent ratio 1:20, slurry to t-butanol ratio 1:1, soaking time 5 min and duty cycle 50%, the mangiferin yield obtained was 54 mg/g by microwave assisted three phase partitioning extraction (MTPP. Thus extraction method developed resulted into higher extraction yield in a shorter span, thereby making it an interesting alternative prior to down-stream processing.
A model for wave propagation in a porous solid saturated by a three-phase fluid.
Santos, Juan E; Savioli, Gabriela B
2016-02-01
This paper presents a model to describe the propagation of waves in a poroelastic medium saturated by a three-phase viscous, compressible fluid. Two capillary relations between the three fluid phases are included in the model by introducing Lagrange multipliers in the principle of virtual complementary work. This approach generalizes that of Biot for single-phase fluids and allows to determine the strain energy density, identify the generalized strains and stresses, and derive the constitutive relations of the system. The kinetic and dissipative energy density functions are obtained assuming that the relative flow within the pore space is of laminar type and obeys Darcy's law for three-phase flow in porous media. After deriving the equations of motion, a plane wave analysis predicts the existence of four compressional waves, denoted as type I, II, III, and IV waves, and one shear wave. Numerical examples showing the behavior of all waves as function of saturation and frequency are presented.
Flexible voltage support control for three-phase distributed generation inverters under grid fault
DEFF Research Database (Denmark)
Camacho, Antonio; Castilla, Miguel; Miret, Jaume
2013-01-01
Operators describe the behavior of the energy source, regulating voltage limits and reactive power injection to remain connected and support the grid under fault. On the basis that different kinds of voltage sags require different voltage support strategies, a flexible control scheme for three phase grid......Ancillary services for distributed generation systems become a challenging issue to smartly integrate renewable energy sources into the grid. Voltage control is one of these ancillary services which can ride through and support the voltage under grid faults. Grid codes from the Transmission System...... connected inverters is proposed. In three phase balanced voltage sags, the inverter should inject reactive power in order to raise the voltage in all phases. In one or two phase faults, the main concern of the distributed generation inverter is to equalize voltages by reducing the negative symmetric...
Four-branch Star Hybrid Power Filter for Three-phase Four-wire Systems
DEFF Research Database (Denmark)
Blaabjerg, Frede; Teodorescu, Remus; Rodriguez, Pedro;
2008-01-01
This paper presents a new concept for filtering current harmonics in three-phase four-wire networks. The four-branch star (FBS) filtering topology presented in this work is characterized by a particular layout consisting of single-phase inductances and capacitors. Via this layout, a power filter...... results is conducted in order to verify and validate the good performance of the proposed four-branch star passive/hybrid power filter....
Modal analysis of untransposed bilateral three-phase lines -- a perturbation approach
Energy Technology Data Exchange (ETDEWEB)
Faria, J.A.B. [Inst. Superior Tecnico, Lisboa (Portugal). Centro de Electrotecnia Teorica e Medidas Electricas; Mendes, J.H.B. [Univ. de Los Andes, Merida (Venezuela). Escuela de Ingenieria Electrica
1997-01-01
Model analysis of three-phase power lines exhibiting bilateral symmetry leads to modal transformation matrices that closely resemble Clarke`s transformation. The authors develop a perturbation theory approach to justify, interpret, and gain understanding of this well known fact. Further, the authors show how to find new frequency dependent correction terms that once added to Clarke`s transformation lead to improved accuracy.
Sliding Mode Controller for Three-Phase Hybrid Active Power Filter with Photovoltaic Application
Blorfan, Ayman; Merckle, Jean; Flieller, Damien; Wira, Patrice; Sturtzer, Guy
2012-01-01
International audience; This paper presents a new three-phase hybrid active power filter configuration that interconnects a passive high-pass filter in parallel with an active power filter and a photovoltaic system. The proposed configuration can improves the filtering performance of the conventional active power filter, as well as simultaneously supply the power from the photovoltaic arrays to the load and utility. This paper will describe the proposed hybrid active power filter control usin...
Vector control of three-phase AC/DC front-end converter
Indian Academy of Sciences (India)
J S Siva Prasad; Tushar Bhavsar; Rajesh Ghosh; G Narayanan
2008-10-01
A vector control scheme is presented for a three-phase AC/DC converter with bi-directional power ﬂow capability. A design procedure for selection of control parameters is discussed. A simple algorithm for unit-vector generation is presented. Starting current transients are studied with particular emphasis on high-power applications, where the line-side inductance is low. A starting procedure is presented to limit the transients. Simulation and experimental results are also presented.
1990-08-01
37 Waste water management and sanitary engineering Airfields and pavements 38 O1 pollution removal and recovery3 Air polution ADVANCED BASE AND...utility systems at Ford Island, Barbers Point Naval Air Station, the Naval Shipyard, and the Naval Supply Center at Pearl Harbor, Hawaii. The main...Power Meter connected to a three-phase 4-wire amorphous core transformer under test at Barbers Point Naval Air Station. This testing procedure was
Energy Technology Data Exchange (ETDEWEB)
Sohn, Myung Hee; Jeong, Hwan Jeong; Lim, Seok Tae [Chonbuk National University Medical School, Jeonju (Korea, Republic of)
2007-02-15
A 44-year-old female underwent three-phase bone scintigraphy for an evaluation of right hip joint pain. The blood-flow and blood-pool images show a pelvic blush with a photopenic center (doughnut) prior to bladder filling. On the three hour delayed image, the pelvic uptake disappeared. The scintigraphic findings indicated the possibility of an early pregnancy. However, plain radiography demonstrated an intrauterine device. A uterine doughnut developed as a result of photon attenuation of intrauterine device.
Analysis of three-phase power transformer laminated magnetic core designs
Directory of Open Access Journals (Sweden)
M.I. Levin
2014-03-01
Full Text Available Analysis and research into properties and parameters of different-type laminated magnetic cores of three-phase power transformers are conducted. Most of new laminated magnetic core designs are found to have significant shortcomings resulted from design and technological features of their manufacturing. These shortcomings cause increase in ohmic loss in the magnetic core, which eliminates advantages of the new core configurations and makes them uncompetitive as compared with the classical laminated magnetic core design.
Analysis of Three-Phase Thyristor Phase Control Circuit with Series RLC Elements
Himei, Toyoji; Nakanishi, Sen-ichiro; Funabiki, Shigeyuki; Komatsubara, Hitoshi; Kurose, Osamu
1983-01-01
An ac phase control circuit by thyristor is widely used in industry, The characteristics of the singlephase circuit with series RLC elements are numerically analyzed, and is reported the interesting phenomenon of step-up voltage without transformer. However, the performance of three phase phase control circuit with series RLC elements is not made clear. In this paper, the performance of three-phasecontrol circuit of a balanced and an unbalanced load with series RLC elements is described. The ...
Design of materials with extreme thermal expansion using a three-phase topology optimization method
DEFF Research Database (Denmark)
Sigmund, Ole; Torquato, S.
1997-01-01
Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases...... materials having maximum directional thermal expansion (thermal actuators), zero isotropic thermal expansion, and negative isotropic thermal expansion. It is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion...
Dynamic quenchers in fluorescently labeled membranes. Theory for quenching in a three-phase system.
Omann, G M; Glaser, M
1985-05-01
The theory for quenching of fluorescently labeled membranes by dynamic quenchers is described for a three-phase system: a fluorescently labeled membrane, a nonlabeled membrane, and an aqueous phase. Two different experimental protocols are possible to determine quenching parameters. Using the first protocol, partition coefficients and bimolecular quenching constants were determined for a hydrophobic quencher in carbazole-labeled membranes in the presence of an unlabeled reference membrane. These parameters determined for 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE) using this three-phase analysis were in good agreement with values determined by a two-phase analysis without the reference lipid. Hence, the theory was verified. In the second protocol, the quencher partition coefficient was determined for unlabeled membranes in the presence of a carbazole-labeled reference membrane. Partition coefficients for DDE determined by this method were the same as partition coefficients determined for carbazole-labeled membranes using the two-phase analysis. The greater ease in determining partition coefficients and bimolecular quenching constants by the three-phase analysis and, in particular, the ability to determine the partition coefficient in unlabeled membranes make the three-phase analysis especially useful. This method was used to study the effect varying the membrane lipid composition has on the partition coefficient. The data indicate that partition coefficients of DDE in fluid membranes are not dramatically dependent upon polar head group composition, fatty acid composition, or cholesterol content. However, partitioning into gel-phase lipids is at least 100-fold less than fluid-phase lipids.
Origin and control of instability in SCR/triac three-phase motor controllers
Dearth, J. J.
1982-01-01
The energy savings and reactive power reduction functions initiated by the power factor controller (PFC) are discussed. A three-phase PFC with soft start is examined analytically and experimentally to determine how well it controls the open loop instability and other possible modes of instability. The detailed mechanism of the open loop instability is determined and shown to impose design constraints on the closed loop system. The design is shown to meet those constraints.
Controlling a Four-Quadrant Brushless Three-Phase dc Motor
Nola, F. J.
1986-01-01
Control circuit commutates windings of brushless, three-phase, permanent-magnet motor operating from power supply. With single analog command voltage, controller makes motor accelerate, drive steadily, or brake regeneratively, in clockwise or counterclockwise direction. Controller well suited for use with energy-storage flywheels, actuators for aircraft-control surfaces, cranes, industrial robots, and other electromechanical systems requiring bidirectional control or sudden stopping and reversal.
Modeling and control of three phase rectifier with electronic smoothing inductor
DEFF Research Database (Denmark)
Singh, Yash Veer; Rasmussen, Peter Omand; Andersen, Torben Ole
2011-01-01
controlled variable impedance. This increases power factor (PF) and reduces total harmonic distortions (THDs) in mains current. The ESI based rectifier enables compact and cost effective design of three phase electric drive as size of passive components is reduced significantly. In order to carry out...... stability and voltage regulation studies, the average, small-signal, dynamic model and control strategy of the ESI is developed and validated by simulation and laboratory measurements....
A Three-Phase Multiobjective Mechanism for Selecting Retail Stores to Close
Directory of Open Access Journals (Sweden)
Rong-Chang Chen
2016-01-01
Full Text Available To operate a successful and growing business, a retail store manager has to make tough decisions about selectively closing underperforming stores. In this paper, we propose using a three-phase multiobjective mechanism to help retail industry practitioners determine which stores to close. In the first phase, a geographic information system (GIS and k-means clustering algorithm are used to divide all the stores into clusters. In the second phase, stores can be strategically selected according to the requirements of the company and the attributes of the stores. In the third phase, a neighborhood-based multiobjective genetic algorithm (NBMOGA is utilized to determine which stores to close. To examine the effectiveness of the proposed three-phase mechanism, a variety of experiments are performed, based partly on a real dataset from a stock-list company in Taiwan. Results from the experiments show that the proposed three-phase mechanism can help efficiently decide which store locations to close. In addition, the neighborhood radius has a considerable influence on the results.
Safety performance of traffic phases and phase transitions in three phase traffic theory.
Xu, Chengcheng; Liu, Pan; Wang, Wei; Li, Zhibin
2015-12-01
Crash risk prediction models were developed to link safety to various phases and phase transitions defined by the three phase traffic theory. Results of the Bayesian conditional logit analysis showed that different traffic states differed distinctly with respect to safety performance. The random-parameter logit approach was utilized to account for the heterogeneity caused by unobserved factors. The Bayesian inference approach based on the Markov Chain Monte Carlo (MCMC) method was used for the estimation of the random-parameter logit model. The proposed approach increased the prediction performance of the crash risk models as compared with the conventional logit model. The three phase traffic theory can help us better understand the mechanism of crash occurrences in various traffic states. The contributing factors to crash likelihood can be well explained by the mechanism of phase transitions. We further discovered that the free flow state can be divided into two sub-phases on the basis of safety performance, including a true free flow state in which the interactions between vehicles are minor, and a platooned traffic state in which bunched vehicles travel in successions. The results of this study suggest that a safety perspective can be added to the three phase traffic theory. The results also suggest that the heterogeneity between different traffic states should be considered when estimating the risks of crash occurrences on freeways.
Cho, Y. S.; Choi, H. S.; Jung, B. I.
2010-11-01
A transformer-type superconducting fault current limiter (SFCL) can control fault current by adjusting a turn's ratio of the primary and secondary windings. In addition, by inserting a neutral line into the secondary winding, the power burden of the superconducting elements can be evenly distributed. We compared the operating and transient characteristics of the three-phase resistive and transformer-type SFCLs in the balanced and unbalanced faults that occur in power systems. In transformer-type SFCLs, where the primary and secondary windings of each phase were connected to one iron core, flux was induced to each winding of the normal phases by the fault current of the fault phase, thus causing simultaneous quench between superconducting elements. In the three-phase power systems, however, when faults occurred in more than two phases, the flux from fault current of the fault phase affected the other normal phase, thus decreasing the reduction ratio of fault current. We confirmed, however, that the fault current was reduced by 70% relative to cases without SFCLs. The results of the analysis of the transient characteristics of the three-phase transformer-type SFCL through the symmetrical component calculus showed that in the case of triple line-to-ground fault, a difference between positive and negative phase currents was large enough to cause an increase in the phase angle (δ) between the generator creating the power and the motor acting as a load. Thus, we expect that the transient stability deteriorates.
Directory of Open Access Journals (Sweden)
Girish Chandra Thakur
2015-05-01
Full Text Available This paper tends to develop for protection for costly appliances which require three-phase AC supply for operation. Failure of any of the phases or sudden change in voltage makes the appliance prone to erratic functioning and may even lead to failure. Hence it is of paramount importance to monitor the availability of the three-phase supply and proper voltage supply and switch off the appliance in the event of failure of one or two phases or if required voltage level is not available. The power to the appliance should resume with the availability of all phases of the supply with proper voltage level. The main advantage of this protector circuit is that it protects three-phase appliances from failure of any phase as well as from fluctuation of voltage. The concept in future can be extended to developing a mechanism to send message to the authority via SMS by interfacing GSM modem. Details description of all types of faults is given below.
Detection of stator winding faults in induction motors using three-phase current monitoring.
Sharifi, Rasool; Ebrahimi, Mohammad
2011-01-01
The objective of this paper is to propose a new method for the detection of inter-turn short circuits in the stator windings of induction motors. In the previous reported methods, the supply voltage unbalance was the major difficulty, and this was solved mostly based on the sequence component impedance or current which are difficult to implement. Some other methods essentially are included in the offline methods. The proposed method is based on the motor current signature analysis and utilizes three phase current spectra to overcome the mentioned problem. Simulation results indicate that under healthy conditions, the rotor slot harmonics have the same magnitude in three phase currents, while under even 1 turn (0.3%) short circuit condition they differ from each other. Although the magnitude of these harmonics depends on the level of unbalanced voltage, they have the same magnitude in three phases in these conditions. Experiments performed under various load, fault, and supply voltage conditions validate the simulation results and demonstrate the effectiveness of the proposed technique. It is shown that the detection of resistive slight short circuits, without sensitivity to supply voltage unbalance is possible.
Energy Technology Data Exchange (ETDEWEB)
Elizondo, Marcelo A.; Tuffner, Francis K.; Schneider, Kevin P.
2016-01-01
Unlike transmission systems, distribution feeders in North America operate under unbalanced conditions at all times, and generally have a single strong voltage source. When a distribution feeder is connected to a strong substation source, the system is dynamically very stable, even for large transients. However if a distribution feeder, or part of the feeder, is separated from the substation and begins to operate as an islanded microgrid, transient dynamics become more of an issue. To assess the impact of transient dynamics at the distribution level, it is not appropriate to use traditional transmission solvers, which generally assume transposed lines and balanced loads. Full electromagnetic solvers capture a high level of detail, but it is difficult to model large systems because of the required detail. This paper proposes an electromechanical transient model of synchronous machine for distribution-level modeling and microgrids. This approach includes not only the machine model, but also its interface with an unbalanced network solver, and a powerflow method to solve unbalanced conditions without a strong reference bus. The presented method is validated against a full electromagnetic transient simulation.
Institute of Scientific and Technical Information of China (English)
郭文杰; 林飞; 郑琼林
2006-01-01
该文以同步旋转坐标系模型为基础,设计了三相电压型PWM整流器的级联式非线性PI控制器.采用双环结构,用三个非线性PI环节实现了对整流器直流电压与功率因数的高性能控制.以误差的非线性函数与传统PI环节构成的级联式控制器,既提高了系统响应的快速性,又增强了抗扰能力,同时计算简单易于实现.与传统PI控制器的仿真对比表明该方法能够明显改善系统的动态性能,而实验结果也验证了非线性PI控制器的优良性能.
A AC-DC Inversion Power Design Based on PWM IC Controller%基于PWM IC芯片控制的开关电源设计
Institute of Scientific and Technical Information of China (English)
王玉德; 韩翠玲; 陈春廷; 孙洪海
2008-01-01
介绍了SG3525 PWM IC芯片的内部结构,基于该芯片设计了15V/36V的开关电源.设计中给出具体的设计电路和参数.经过实验验证该系统控制可靠,稳定性好,纹波系数低,能够很好地适应电源电压10%和负载20%的变化,具有一定的实际应用价值.
Alawasa, Khaled Mohammad
Voltage-source converters (VSCs) have gained widespread acceptance in modern power systems. The stability and dynamics of power systems involving these devices have recently become salient issues. In the small-signal sense, the dynamics of VSC-based systems is dictated by its incremental output impedance, which is formed by a combination of 'passive' circuit components and 'active' control elements. Control elements such as control parameters, control loops, and control topologies play a significant role in shaping the impedance profile. Depending on the control schemes and strategies used, VSC-based systems can exhibit different incremental impedance dynamics. As the control elements and dynamics are involved in the impedance structure, the frequency-dependent output impedance might have a negative real-part (i.e., a negative resistance). In the grid-connected mode, the negative resistance degrades the system damping and negatively impacts the stability. In high-voltage networks where high-power VSC-based systems are usually employed and where sub-synchronous dynamics usually exist, integrating large VSC-based systems might reduce the overall damping and results in unstable dynamics. The objectives of this thesis are to (1) investigate and analyze the output impedance properties under different control strategies and control functions, (2) identify and characterize the key contributors to the impedance and sub-synchronous damping profiles, and (3) propose mitigation techniques to minimize and eliminate the negative impact associated with integrating VSC-based systems into power systems. Different VSC configurations are considered in this thesis; in particular, the full-scale and partial-scale topologies (doubly fed-induction generators) are addressed. Additionally, the impedance and system damping profiles are studied under two different control strategies: the standard vector control strategy and the recently-developed power synchronization control strategy
Moment Stability of the Critical Case of PWM Feedback Systems with Stochastic Perturbations
Directory of Open Access Journals (Sweden)
Zhong Zhang
2012-01-01
Full Text Available This paper further studies the moment stability of pulse-width-modulated (PWM feedback system which is subjected to multiplicative and additive random disturbance modeled by the derivative of Wiener process. Different from the existing investigation, we focus on its critical case. The linear plant considered herein is assumed to be critically stable; that is, the plant has one and only one pole at the origin, and the rest of the poles are left half of complex plane. We establish several globally asymptotically stability criteria for such PWM feedback systems and then propose an algorithm to calculate the stability bound effectively. Furthermore, we present two numerical examples to show the effectiveness of the theoretical results.
Conversor Boost PWM Entrelaçado com Comutação Suave
Directory of Open Access Journals (Sweden)
Lúcio dos Reis Barbosa
2002-01-01
Full Text Available Este artigo apresenta uma topologia aprimorada de um conversor Boost PWM com comutação suave. O circuito proposto, tendo duas chaves ativas entrelaçadas, opera com chaveamento suave, sob odulação PWM (pulse-width-modulation. Além disso, este conversor fornece alta rendimento sob as condições de operação, para uma larga variação de carga, e operando à altas freqüências. Para ilustrar o princípio de operação deste novo conversor apresenta-se um estudo pormenorizado, incluindo simulações e resultados. A validade deste novo conversor é confirmada por meio dos resultados obtidos.
Fundamental Approach in Digital Circuit Design for 1-MHz Frequency PWM Gate Drive Application
Directory of Open Access Journals (Sweden)
Nor Zaihar Yahaya
2011-01-01
Full Text Available This paper discusses the design of a digital programmable logic circuit to produce a 5 V - output square wave pulses for four high power MOSFET switches using a fixed PWM circuit. It will be applied to drive the synchronous rectifier buck converter(SRBC circuit. The PWM signals with multiple fixed time delay of 15 ns, 232 ns, 284 ns and 955 ns are generated. The steps taken to analyze each propagation time delay of each logic gate used and its combination are carefully studied. A multiplexer is added at the output of the logic circuit to select and produce the desired output pulses of 20% duty ratio. The logic outputs are compared with the analog pulses and results match each other within 1% in difference.
Study of a New HighPowerFactor ThreePhase ACDC Converter%新型高功率因数三相ACDC变换器的研究
Institute of Scientific and Technical Information of China (English)
陈爱萍; 李朝健; 张深基
2001-01-01
提出一种新型高功率因数三相AC-DC变换器，由一个同步变压器（LIT）、两个三相二极管整流器、一个脉冲宽度调制（PWM）DC-DC变换器组成，输入变换器的交流电流频率固定且不连续，排除了三次、五次、七次谐波．通过LIT和平衡电抗器的电流是高频的，变压器可用小铁芯．分析了其电路拓扑结构、工作原理，并给出实验结果．%This paper proposes a new high-power-factor three-phase AC-DC converter, which is composed of a line interphase transformer (LIT) and two three-phase diode rectifiers, followed by a pulse width modulation (PWM) DC-DC boost converter. The active switch of the boost converter is gated at a constant frequency so that the AC input current is discontinuous. This procedure provides an input current shaping without the third, fifth, and seventh harmonics. The current that flows through the LIT and boost inductors has such a high frequency,and ferrite cores of a small size can be utilized in transformer. This paper analyzes it s circuit topological structure , principle of operation , and gives experimental result.
High-Frequency Link Inverter for Fuel CellsBased on Multiple-Carrier PWM
Institute of Scientific and Technical Information of China (English)
无
2005-01-01
A similar circuit as Fig. 12 can be realized with MOSFET or IGBT devices configured as bi-directional pairs in the output bridge. In this case, the complete process in Fig. 8 would be needed to generate the complete 50% gate drive pulses. The 50% gate pulses still support pulse transformer coupling, retaining the simplicity of the gate drive isolation. The PWM cycloconverter process scales directly to higher switching speeds possible with these devices.
Closed loop control of ZVS half bridge DC-DC converter with DCS PWM Control
Directory of Open Access Journals (Sweden)
JANAPATI SIVAVARA PRASAD
2012-10-01
Full Text Available
The main drawback of the conventional symmetric control is that both primary switches in the converter operate at hard switching condition. Moreover, during the off-time period of two switches, the oscillation between the transformer leakage inductance and junction capacitance of the switches results in energy dissipation and electromagnetic interference (EMI emissions due to reverse recovery of MOSFETs body diodes. The asymmetric (complementary control was proposed to achieve ZVS operation for HB switches. However, asymmetric stresses distribution on the corresponding components may occur due to the asymmetric duty cycle distribution for the two primary switches. A new control scheme, to be known as duty-cycle shifted PWM (DCS PWM control, is proposed and applied to the conventional HB dc–dc converters to achieve ZVS for both the switches without adding extra components and without adding asymmetric penalties of the complementary control. The concept of this new control scheme is shifting one of the two symmetric PWM driving signals close to the other, such that ZVS may be achieved for the lagging switch due to the shortened resonant interval. Moreover, based on the DCS PWM control, a new half-bridge topology is proposed to achieve ZVS for both the main switches and auxiliary switch by adding an auxiliary switch and diode in the proposed half bridge. ZVS for the switch is achieved by utilizing the energy trapped in the leakage inductance. There are two control schemes. One is open loop and the other is closed loop. In open loop scheme, the given dc-dc converter is operating under disturbance. This disturbance effect is eliminated in closed loop scheme.
Modelling of a double star induction motor for space vector PWM control
Energy Technology Data Exchange (ETDEWEB)
Hadiouche, D.; Razik, H.; Rezzoug, A. [Groupe de Recherche en Electrotechnique et Electronique de Nancy, G.R.E.E.N. - CNRS UPRES, University H. Poincare, Vandoeuvre-les-Nancy (France)
2000-08-01
In this paper, we present the analysis and the modelling of a Double-Star Induction Motor (DSIM). A steady-state model is first established in order to analyse its harmonic behaviour. Then, a new transformation matrix is proposed in order to develop a suitable dynamic model. In both cases, the study is made using an arbitrary shift angle between the two stars. At last, a space vector Pulse Width Modulation (PWM) control or the DSIM is simulated. (orig.)
A digitally controlled PWM/PSM dual-mode DC/DC converter
Institute of Scientific and Technical Information of China (English)
Zhen Shaowei; Zhang Bo; Luo Ping; Hou Sijian; Ye Jingxin; Ma Xiao
2011-01-01
A digitally controlled pulse width modulation/pulse skip modulation (PWM/PSM) dual-mode buck DC/DC converter is proposed.Its operation mode can be automatically chosen as continuous conduction mode (CCM) or discontinuous conduction mode (DCM).The converter works in PSM at DCM and in 2 MHz PWM at CCM.Switching loss is reduced at a light load by skipping cycles.Thus high conversion efficiency is realized in a wide load current.The implementations of PWM control blocks,such as the ADC,the digital pulse width modulator (DPWM) and the loop compensator,and PSM control blocks are described in detail.The parameters of the loop compensator can be programmed for different external component values and switching frequencies,which is much more flexible than its analog rivals.The chip is manufactured in 0.13 μm CMOS technology and the chip area is 1.21 mm2.Experimental results show that the conversion efficiency is high,being 90% at 200 mA and 67% at 20 mA.Meanwhile,the measured load step response shows that the proposed dual-mode converter has good stability.
A three-phase microfluidic chip for rapid sample clean-up of alkaloids from plant extracts
Tetala, K.K.R.; Swarts, J.W.; Chen, B.; Janssen, A.E.M.; Beek, van T.A.
2009-01-01
A three-phase microchip was developed for the rapid and efficient small-scale purification of alkaloids from plant extracts. As part of the development of such a three-phase microchip, first a two-phase microchip with two channels (3.2 cm and 9.3 cm) was used to study the extraction efficiency of st
零电压转换PWMDC/DC变换器的研究%Research on Zero-voltage-transition PWM DC/DC Converters
Institute of Scientific and Technical Information of China (English)
高原; 邱新芸
2005-01-01
介绍了PWM DC/DC变换器的软开关控制.阐述了零电压转换PWM DC/DC变换器的缺点.研究了带吸收电容的零电压转换PWM DC/DC变换器电路.给出了仿真电路和仿真结果.
Energy Technology Data Exchange (ETDEWEB)
Hong, Chae Moon; Ahn, Byeong Cheol; Choi, So Young; Kim, Do Hoon; Lee, Sang Woo; Kwon, Tae Geon; Lee, Jaetae [Kyungpook National Univ., Daegu (Korea, Republic of)
2012-09-15
Bisphosphonate (BP) related osteonecrosis of the jaw (BRONJ) is a well known serious complication of BP treatment. This study was undertaken to evaluate the diagnostic usefulness of three phase bone scintigraphy in patients with BRONJ. Forty one patients (48 lesions)with clinically proven BRONJ (2 males, 39 females, age 74.3{+-}6.7 years)under went Tc 99m HDP bone scintigraphy. Visual interpretation and semiquantitative analysis of uptakes using lesion to contralateral uptake ratios during the blood pool phase (BUR)and during the osseous phase (OUR)were performed, and relations were sought between these and various clinical parameters. Three phase bone scintigraphy showed increased perfusion and blood pooling in 21 (63.6%)and 27 (81.8%)of 33 lesions, respectively. The osseous phase was positive for 45 (93.8%)of the 48 lesions. Of the four inflammatory clinical parameters of BRONJ [pus discharge, pain, swelling, and erythrocyte sedimentation rate (ESR)], patients with three or more parameters had more positive findings in vascular and blood pool phase images (p=0.033, p=0.027). By semiquantitative analysis, patients with a positive ESR had statistically higher BUR and OUR (both p<0.001). Higher stage BRONJ lesions had higher OUR than lower stage lesions (p=0.003). In addition, bone scintigraphy revealed three clinically covert BRONJ lesions without bone exposure, and four patients were up staged based on bone scintigraphy. Bone scintigraphy provides a relatively sensitive means of detecting BRONJ, so it was helpful for accurate BRONJ staging. Furthermore, Increased uptakes in vascular and blood pool phases of three phase bone scintigraphy were related to the inflammatory activity of BRONJ.
Three-phase metal kinetics in terrestrial invertebrates exposed to high metal concentrations
Energy Technology Data Exchange (ETDEWEB)
Laskowski, Ryszard, E-mail: ryszard.laskowski@uj.edu.pl [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Bednarska, Agnieszka J. [Institute of Environmental Sciences, Jagiellonian University, Gronostajowa 7, 30-387 Krakow (Poland); Spurgeon, David; Svendsen, Claus [Centre for Ecology and Hydrology, Maclean Building, Benson Lane, Crowmarsh Gifford, Wallingford, Oxon, OX10 8BB (United Kingdom); Gestel, Cornelis A.M. van [Institute of Ecological Science, Vrije Universiteit, De Boelelaan 1085, 1081 HV Amsterdam (Netherlands)
2010-08-15
Models of metal toxicokinetics are critically evaluated using both newly generated data in the NoMiracle project as well as those originating from older studies. The analysis showed that the most frequently used one-compartment two-phase toxicokinetic model, with one assimilation and one elimination rate constant, does not describe correctly certain data sets pertaining particularly to the pattern of assimilation of trace elements. Using nickel toxicokinetics in carabid beetles and earthworms as examples, we showed that Ni in fact exhibits a three-phase kinetics with a short phase of fast metal accumulation immediately after exposure, followed by partial elimination to an equilibrium concentration at a later stage of a metal exposure phase, and by final elimination upon transfer to an uncontaminated food/soil. A similar phenomenon was also found for data on cadmium kinetics in ground beetles and copper kinetics in earthworms in data already published in the literature that was not accounted for in the earlier analysis of the data. The three-phase model suggests that the physiology of controlling body metal concentrations can change shortly after exposure, at least in some cases, by increasing the elimination rate and/or decreasing metal assimilation. Hence, the three-phase model, that allows for different assimilation and/or elimination rates in different phases of exposure to a toxicant, may provide insight into temporal changes in the physiology of metal handling. Consequently, this alternative model should always be tested when describing metal toxicokinetics when temporal patterns of internal metal concentration exhibit an initial 'overshoot' in body metal concentrations.
Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line.
Zhou, Qiang; He, Wei; Xiao, Dongping; Li, Songnong; Zhou, Kongjun
2015-12-30
A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid.
Study and Experiment on Non-Contact Voltage Sensor Suitable for Three-Phase Transmission Line
Directory of Open Access Journals (Sweden)
Qiang Zhou
2015-12-01
Full Text Available A voltage transformer, as voltage signal detection equipment, plays an important role in a power system. Presently, more and more electric power systems are adopting potential transformer and capacitance voltage transformers. Transformers are often large in volume and heavyweight, their insulation design is difficult, and an iron core or multi-grade capacitance voltage division structure is generally adopted. As a result, the detection accuracy of transformer is reduced, a huge phase difference exists between detection signal and voltage signal to be measured, and the detection signal cannot accurately and timely reflect the change of conductor voltage signal to be measured. By aiming at the current problems of electric transformation, based on electrostatic induction principle, this paper designed a non-contact voltage sensor and gained detection signal of the sensor through electrostatic coupling for the electric field generated by electric charges of the conductor to be measured. The insulation structure design of the sensor is simple and its volume is small; phase difference of sensor measurement is effectively reduced through optimization design of the electrode; and voltage division ratio and measurement accuracy are increased. The voltage sensor was tested on the experimental platform of simulating three-phase transmission line. According to the result, the designed non-contact voltage sensor can realize accurate and real-time measurement for the conductor voltage. It can be applied to online monitoring for the voltage of three-phase transmission line or three-phase distribution network line, which is in accordance with the development direction of the smart grid.
BASIC SOLUTION FOR THE THREE-PHASE COMPOSITE CONSTITUTIVE MODEL IN ANTIPLANE PIEZOELECTRICITY
Institute of Scientific and Technical Information of China (English)
Wang Xu; Shen Yapeng
2000-01-01
A basic solution in series form for the three-phase composite cylindrical model in antiplane piezoelectricity subjected to the action of a singularity in the intermediate matrix region is presented. The so lution is obtained through the complex potential approach in conjunction with the techniques of analytical con tinuation, singularity analysis, Laurent series expansion in an annular region and Cauchy integral formulae, etc. Based on the complex potentials obtained, explicit expressions for the distribution of stress and electric displacement in the three regions are also derived.
Sharing of nonlinear load in parallel-connected three-phase converters
DEFF Research Database (Denmark)
Borup, Uffe; Blaabjerg, Frede; Enjeti, Prasad N.
2001-01-01
In this paper, a new control method is presented which enables equal sharing of linear and nonlinear loads in three-phase power converters connected in parallel, without communication between the converters. The paper focuses on solving the problem that arises when two converters with harmonic...... compensation are connected in parallel. Without the new solution, they are normally not able to distinguish the harmonic currents that flow to the load and harmonic currents that circulate between the converters. Analysis and experimental results on two 90-kVA 400-Hz converters in parallel are presented....... The results show that both linear and nonlinear loads can be shared equally by the proposed concept....
PEBB Feedback Control Low Library. Volume 1: Three-Phase Inverter Control Algorithms
1999-01-01
ship propulsion electrical loads are powered from a common set of prime movers. Presently, the current generation of PEBB-like devices include high-power, fast-switching, high-bandwidth dc-dc converters and dc-ac inverters. This report summarized the algorithms required to control a conventional three-phase inverter. First, implementation issues regarding the Sine-Triangle Pulse-Width-Modulation and Space-Vector Modulation are presented with an emphasis placed on digital realizations. Then, two current control schemes are documented via analysis, design example, and
Three-phase heaters with common overburden sections for heating subsurface formations
Energy Technology Data Exchange (ETDEWEB)
Vinegar, Harold J [Bellaire, TX
2012-02-14
A heating system for a subsurface formation is described. The heating system includes three substantially u-shaped heaters with first end portions of the heaters being electrically coupled to a single, three-phase wye transformer and second end portions of the heaters being electrically coupled to each other and/or to ground. The three heaters may enter the formation through a first common wellbore and exit the formation through a second common wellbore so that the magnetic fields of the three heaters at least partially cancel out in the common wellbores.
Hydraulic conductance and viscous coupling of three-phase layers in angular capillaries
Dehghanpour, H.; Aminzadeh, B.; Dicarlo, D. A.
2011-06-01
Predicting three-phase relative permeability by network models requires reliable models for hydraulic conductance of films and layers stabilized by capillary forces at the pore level. We solve the creeping flow approximation of the Navier-Stokes equation for stable wetting and intermediate layers in the corner of angular capillaries by using a continuity boundary condition at the layer interface. We find significant coupling between the condensed phases and calculate the generalized mobilities by solving cocurrent and countercurrent flow of wetting and intermediate layers. Finally, we present a simple heuristic model for the generalized mobilities as a function of the geometry and viscosity ratio.
Nonuniform three-phase power lines: resonance effects due to conductor transposition
Energy Technology Data Exchange (ETDEWEB)
Brandao Faria, J.A.; Guerreiro das Neves, M.V. [Instituto Superior Tecnico, Lisbon (Portugal). Centro de Electrotecnia Teorica e Medidas Electricas
2004-02-01
This paper is concerned with nonuniform power line modelling. It deals with the resonance effects produced by conductor transposition in long overhead three-phase lines. A frequency- domain analysis is conducted showing that the modal propagation parameters characterising the transmission line structure exhibit a repetitive resonant behaviour for frequencies such that the overall transposition cycle length gets close to an integer multiple of one half wavelength. Consideration of these resonance phenomena is of major importance and should be taken into account in a variety of situations, for example, in power line carrier communications and line transient studies. (author)
A nonconventional method for fast starting of three phase wound-rotor induction motors
Energy Technology Data Exchange (ETDEWEB)
Badr, M.A.; Abdel-halim, M.A.; Alolah, A.I. [King Saud Univ., Riyadh (Saudi Arabia)
1996-12-01
This paper presents a nonconventional method for fast starting of three phase wound rotor induction motors. This is achieved through shunting the stator and rotor windings across the supply for a predetermined short period. By this connection, the motor produces an extremely high starting torque. The feasibility of this basic idea has been confirmed through investigating the starting transients corresponding to this mode of operation. For this purpose, a rigorous state space mathematical model has been developed and simulated. The validity of the proposed method and the findings from the mathematical model have been confirmed experimentally.
THREE -PHASE CIRCULATING FLUIDIZED BED EVAPORATOR FOR WHEAT STRAW BLACK LIQUOR EVAPORATION
Institute of Scientific and Technical Information of China (English)
Yuan-yuan Jia
2004-01-01
A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China′s papermaking industry. It is treated by alkali recovery,in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20% ～40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.
THREE -PHASE CIRCULATING FLUIDIZED BED EVAPORATOR FOR WHEAT STRAW BLACK LIQUOR EVAPORATION
Institute of Scientific and Technical Information of China (English)
Yuan-yuanJia
2004-01-01
A novel vapor-liquid-solid circulating fluidized bed evaporator, meaning for enhancing heat transfer and preventing fouling, is applied to wheat straw black liquor, which is the primary pollutant in China's papermaking industry. It is treated by alkali recovery, in which evaporation is a key process. The experimental results show that the vapor-liquid-solid three-phase boiling heat transfer coefficient is enhanced by 20%-40% than that of vapor-liquid two-phase boiling flow, also, the novel evaporator exhibits an excellent function of fouling prevention.
Intelligent power factor compensation equipment of three phase low voltage loads
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
An intelligent power factor correction scheme is presented for three phase low power factor loads. This new scheme is able to perform individual phase sensing of parameters by monitoring at all times to sense a change in system parameters and affects individual phase correction by applying the exact amount of reactive components needed for each phase, and can also reduce negative sequence current caused by the load to improve system balance. An optimization criterion is used for the proper calculation of reactive power steps in a power compensation installation of capacitor banks. The criterion is enabled by sampling measurements performed on the electrical plant examined within specific interval of time.
Optimal power flow based on glow worm-swarm optimization for three-phase islanded microgrids
DEFF Research Database (Denmark)
Quang, Ninh Nguyen; Sanseverino, Eleonora Riva; Di Silvestre, Maria Luisa
2014-01-01
This paper presents an application of the Glowworm Swarm Optimization method (GSO) to solve the optimal power flow problem in three-phase islanded microgrids equipped with power electronics dc-ac inverter interfaced distributed generation units. In this system, the power injected by the distributed...... generation units and the droop control parameters are considered as variables to be adjusted by a superior level control. Two case studies with different optimized parameters have been carried out on a 6-bus test system. The obtained results showed the effectiveness of the proposed approach and overcomes...
Sensorless Modeling of Varying Pulse Width Modulator Resolutions in Three-Phase Induction Motors
Marko, Matthew David; Shevach, Glenn
2017-01-01
A sensorless algorithm was developed to predict rotor speeds in an electric three-phase induction motor. This sensorless model requires a measurement of the stator currents and voltages, and the rotor speed is predicted accurately without any mechanical measurement of the rotor speed. A model of an electric vehicle undergoing acceleration was built, and the sensorless prediction of the simulation rotor speed was determined to be robust even in the presence of fluctuating motor parameters and significant sensor errors. Studies were conducted for varying pulse width modulator resolutions, and the sensorless model was accurate for all resolutions of sinusoidal voltage functions. PMID:28076418
SPEED CONTROL FOR THREE PHASE INDUCTION MOTOR USING ADALINE NEURAL NETWORKS
Directory of Open Access Journals (Sweden)
Bogdan Codreş
2015-12-01
Full Text Available The speed control of the three phase induction motor is still a challenging problem. Although the results obtained by means of the conventional control are very good, many researches in this area are ongoing. The authors propose a different control approach based on artificial intelligence. The control signals for speed, torque and flux regulation are computed using three ADALINE (Adaptive Linear Neuron neural networks. The numerical simulations are made in Simulink and the obtained results are compared with the conventional drive approach (cascaded PI controller
Vector Controlled Two Phase Induction Motor and To A Three Phase Induction Motor
Directory of Open Access Journals (Sweden)
K.krishna Rao (PG student
2014-12-01
Full Text Available This paper presents vector controlled of single phase induction motor. some problems are with vector controlled SPIM.As SPIM’s are typically to maintain speed and also about the complex implementation of vector controlled SPIM.the implemantion of the proposed vector controlled TPIM compared to the vector controlled SPIM. The general modal sutable for vector control of the unsymmentrical two phase induction motor and also stator flux oriented controlled strategies are analized. the comparative performance of both has been presented in this work with help of a practical three phase motor.
A parametric study on unbalanced three phase islanded microgrids with inverter interfaced units
DEFF Research Database (Denmark)
Sanseverino, Eleonora Riva; Quang, Ninh Nguyen; Zizzo, Gaetano;
2013-01-01
In this paper, the solution of the power flow for unbalanced three phase microgrids systems is proposed. The study aims at the integration of inverter interfaced units using the control law used for primary voltage and frequency regulation, so as to take into account possible small variations...... of these parameters to account for sudden load changes. The proposed study deals with unbalanced systems which is the typical case of small distribution systems and shows how the power losses term varies as the regulators parameters vary as well, thus showing that these are sensitive parameters that could have...... an important role in optimal management of such systems....
A Multipulse Pattern Modulation Scheme for Harmonic Mitigation in Three-Phase Multimotor Drives
DEFF Research Database (Denmark)
Davari, Pooya; Yang, Yongheng; Zare, Firuz;
2016-01-01
, which thus deteriorates the power grid quality and also lowers the conversion efficiency. Both degradations are apt to occur in motor drive applications. At present, many industrial drives are equipped with three-phase diode rectifiers and employ passive filtering techniques on the AC or DC side...... of the rectifier. In such topologies, it is difficult to implement the prior-art harmonic control strategies. Moreover, the total cost and complexity has become the main obstacle for these harmonic elimination approaches in multiple drive systems. Therefore, in this paper, a new cost-effective harmonic mitigation...
DEFF Research Database (Denmark)
Traeholt, C.; Veje, E.; Tønnesen, Ole
2002-01-01
A 10 m long high temperature superconducting (HTS) cable conductor was placed in a plane three-phase arrangement. The test-bed enabled us to study the conductor losses for different separations between the phases. The superconductor was fixed symmetrically in the centre, whilst the two outer conv...... a calorimetric technique where the temperature increase in the flowing LN2 was measured with a set of thermo-couples. Results indicate that the total AC loss increases significantly when the separation between the conductors is reduced....
PWM整流器的欠驱动特性与非线性控制%Underactuated Property and Nonlinear Control for PWM Rectifier
Institute of Scientific and Technical Information of China (English)
张晓华; 郭源博; 周鑫; 陈宏钧
2011-01-01
针对三相电压型脉宽调制（pulsewidthmodulation，PWM）整流器级联式双闭环控制系统结构的选择成因尚缺乏理论阐释的问题，基于欠驱动系统理论对此结构进行理论研究。建立PWM整流器在砌同步旋转坐标系下的数学模型，并对其欠驱动特性进行分析。给出PWM整流器驱动变量与欠驱动变量的选择方法，利用零动态分析理论与部分反馈线性化控制策略，设计电流内环控制器。为增强PWM整流器抵抗电网电压和负载扰动的能力，提出白抗扰比例积分电压外环非线性控制方案。所设计的PWM整流器控制系统具有较好的稳态和动态性能，特别是对电网电压／负载扰动具有很强的鲁棒性。仿真与实物实验结果证明了所提理论的正确性和控制策略的有效性。%Based on the underactuated system theory, the cascaded double-closed-loop control system structure of the three-phase voltage-type pulse width modulation （PWM） rectifier was studied theoretically for lack of effective interpretation for choosing this specific structure. The underactuated property of PWM rectifier was analyzed with its model in the dq synchronous reference frame. The choosing method for actuated and underactuated variables was given. Consequently, the current inner-loop controller was designed, based on the zero dynamics theory and partial feedback linearization control method. Moreover, auto-disturbance- rejection proportional integral （ADR-PI） voltage outer-loop controller was presented to reinforce the rejection ability for the AC voltage and DC load disturbances. The proposed PWM rectifier control system has better steady and dynamic performances, as well as strong robustness for the disturbances especially. Simulation and practical experiment results validate the correctness of the proposed theory and the effectiveness of the control strategy.
矩阵变换器的谐波注入PWM控制策略%Harmonic injected PWM control strategy for matrix converter
Institute of Scientific and Technical Information of China (English)
王汝田; 王秀云; 崔永恒
2013-01-01
The non-controlled rectification and HIPWM(Harmonic Injected PWM) are respectively applied to the virtual rectifier and virtual inverter of equivalent AC/DC/AC model for matrix converter.The virtual rectifier generates fluctuant DC voltage when symmetric or asymmetric three-phase voltages are supplied.The compensation function is deduced based on the concept of switching function for compensating the modulation wave to eliminate the effect of fluctuant DC voltage on the HIPWM output voltage of virtual inverter.Its hardware implementation is very simple.Results of simulation with MATLAB/Simulink show that,the voltage gain of matrix converter can reach to 0.866,the theoretical maximum,and there is no loworder harmonics in its output voltage,verifying the correctness and effectiveness of the proposed control strategy.%在矩阵变换器间接变换法等效的交直和直交2个虚拟的环节上,分别采用不控整流和谐波注入PWM(HIPWM)2种简单易实现的调制方式.在三相输入电压是对称或非对称的情况下,虚拟整流环节输出的是直流波动电压,为消除此直流波动电压对虚拟逆变环节HIPWM输出的电压波形的影响,利用开关函数概念推导了对HIPWM的调制波进行补偿的补偿函数,此控制策略的硬件实现电路非常简单.应用MATLAB/Simulink进行了仿真,仿真结果表明:应用HIPWM控制策略,矩阵变换器的电压增益能够达到理论最大值0.866,输出电压中不含低次谐波,验证了所提控制算法的正确性和有效性.
Institute of Scientific and Technical Information of China (English)
胡跃伟; 鲁明; 田利梅; 武登云
2014-01-01
控制力矩陀螺框架电机驱动电路采用的脉宽调制方式不同,所产生的电机转矩脉动也会不同.针对无刷直流电机驱动的控制力矩陀螺框架系统,从换相期间转矩脉动、非换相期间转矩脉动及脉宽调制方式的应用改进3个方面对不同脉宽调制方式进行分析,得出采用PWM_ON PWM方式的转矩脉动最小,适用于控制力矩陀螺框架系统的高精度控制要求.通过仿真验证了分析的正确性.
Design of 0.18 μm CMOS bandgap reference voltage source%0.18μm CMOS带隙基准电压源的设计
Institute of Scientific and Technical Information of China (English)
陈双文; 刘章发
2011-01-01
Reference voltage source can be used broadly in ADC, DAC, RAM, flash memory and other integrated circuit. This paper designed a high stability, low temperature coefficient and 0.6 V output bandgap reference voltage source using 0.18 μm CMOS.%基准电压源可广泛应用于A/D、D/A转换器、随机动态存储器、闪存以及系统集成芯片中.使用0.18 μm CMOS工艺设计了具有高稳定度、低温漂、低输出电压为0.6 V的CMOS基准电压源.
Analysis of Torque Ripple Caused by Three-Phase Unbalance in Claw Teeth Motors
Koyama, Takayuki; Nakatsugawa, Junnosuke; Enomoto, Yuji
A soft magnetic composite (SMC) has some advantages, namely, three-dimensional magnetic isotropy and low eddy current loss. Thus, it can be used to build a new type of motor with a three-dimensional structure, improved space factor of winding improved the power density. A claw teeth motor is one of the motors that have three-dimensional structure, and it is made of an SMC. Due to its structure, the claw teeth motor has an unbalanced three-phase magnetic circuit, which leads to low-order harmonic components in the torque waveform. For reducing the torque ripple, it is important to estimate the magnetic torque and the cogging torque because the total torque is the sum of these torques. In this study a method for decomposing the total torque under the load condition into the magnetic torque and cogging torque is presented. The proposed method can quantitatively estimate low-order harmonic components of the magnetic torque and cogging torque caused by an unbalanced three-phase magnetic circuit for each phase.
EXPERIMENTAL AND NUMERICAL SIMULATION OF THREE-PHASE FLOW IN AN AERATION TANK
Institute of Scientific and Technical Information of China (English)
Cheng Wen; Zhou Xiao-de; Song Ce; Min Tao; Murai Yuichi; Yamamoto Fujio
2003-01-01
Aeration plays an important role in the treatment of activated sludge due to the interactions among bubbles, sewage and activated sludge in an aeration tank. The aeration performance is directly concerned with the efficiency of sewage disposal. So the three-dimensional two-fluid model was established with emphasis on the phase interaction terms in this paper. This model, as an extension of the two-phase flow model, involved the motion laws of three-phases, and was compared with experimental studies. The finite volume method was used in the numerical simulation of gas-liquid two-phase flow and gas-liquid-solid three-phase flow. In order to discuss the influence of gas-phase, liquid-phase and solid-phase motions in an aeration tank on the sewage disposal, three kinds of boundary and initial conditions were adopted. The simulated results of the flow structure show qualitatively good agreement with the experimental data. And the theoretical basis for designing the best aeration tank was discussed according to the simulated results.
Three-phase bone studies in hemiplegia with reflex sympathetic dystrophy and the effect of disuse
Energy Technology Data Exchange (ETDEWEB)
Greyson, N.D.; Tepperman, P.S.
1984-04-01
Eighty-five patients with cerebral vascular accidents were assessed with three-phase bone scintigraphy of the hands and with whole-body delayed bone imaging. Nine patients (10%) had normal three-phase bone images. Fifty-five patients (65%) showed decreased blood flow and blood-pool images of the hands and wrists with normal delayed bone scintigrams, indicating the effect of paralysis or disuse. Twenty-one patients (25%) had diffuse increased uptake with periarticular accentuation, felt to be bone-scintigraphic evidence of reflex sympathetic dystrophy of the hands and wrists; in two patients this occurred before its clinical appearance. Thriteen of the 21 reflex sympathetic dystrophy syndromes (RDS)-involved limbs (62%) had increased blood flow, whereas 8 (38%) had decreased flow. Gross limb blood flow appears to be related to the degree of muscle activity, but flow may be altered by the presence of sympathetic changes. A possible dissociation between whole-limb flow and bone blood flow in paralyzed limbs involved with RDS is discussed.
Noise and Vibration Monitoring for Premium Efficiency IE 3 Three-Phase Induction Motors
Directory of Open Access Journals (Sweden)
NISTOR, C. G.
2015-08-01
Full Text Available The paper presents the original SV-100 platform that enables low-cost and very high accuracy determinations of noise and vibration levels. The aim of the proposed platform is to achieve an effective integration of the two topics of this analysis: vibrations and noises. To the best of our knowledge, no low price, dedicated compact platform with embedded measuring instruments exists. For proving the practical utility of the proposed platform, two induction motors of 7.5 kW and 11 kW, respectively, in single-layer winding, at 1000 rpm, with IE3 premium efficiency were analyzed. This analysis is required because, according to IEC60034-30 standard, the IE3 efficiency standard has become mandatory for induction motors of rated power greater than 7.5 kW. Therefore, in order to improve the motor operating efficiency, the power losses caused by noises and vibrations have to be reduced. Several variants of supply were studied, i.e., by the three-phase 50 Hz network and by a three-phase inverter at 40, 50 and 60 Hz, respectively. The experimental determinations of noises are presented comparatively, by using a Bruel&Kjaer sonometer and by using the new platform SV-100. The results are compared with the IEC60034 standard.
Three-phase interactions and interfacial transport phenomena in coacervate/oil/water systems.
Dardelle, Gregory; Erni, Philipp
2014-04-01
Complex coacervation is an associative liquid/liquid phase separation resulting in the formation of two liquid phases: a polymer-rich coacervate phase and a dilute continuous solvent phase. In the presence of a third liquid phase in the form of disperse oil droplets, the coacervate phase tends to wet the oil/water interface. This affinity has long been known and used for the formation of core/shell capsules. However, while encapsulation by simple or complex coacervation has been used empirically for decades, there is a lack of a thorough understanding of the three-phase wetting phenomena that control the formation of encapsulated, compound droplets and the role of the viscoelasticity of the biopolymers involved. In this contribution, we review and discuss the interplay of wetting phenomena and fluid viscoelasticity in coacervate/oil/water systems from the perspective of colloid chemistry and fluid dynamics, focusing on aspects of rheology, interfacial tension measurements at the coacervate/solvent interface, and on the formation and fragmentation of three-phase compound drops.
Mean-field Density Functional Theory of a Three-Phase Contact Line
Lin, Chang-You
A three-phase contact line in a three-phase fluid system is modeled by a mean-field density functional theory. We use a variational approach to find the Euler-Lagrange equations. Analytic solutions are obtained in the two-phase regions at large distances from the contact line. We employ a triangular grid and use a successive over-relaxation method to find numerical solutions in the entire domain for the special case of equal interfacial tensions for the two-phase interfaces. We use the Kerins-Boiteux formula to obtain a line tension associated with the contact line. This line tension turns out to be negative. We associate line adsorption with the change of line tension as the governing potentials change. We develop a geometrical interpretation to generalize our potential in order to study less symmetric systems as occur in some practical phase diagrams. A set of special cases of this new potential are linear transformations from our original potential. In those special cases, we can obtain solutions by scaling of our former results.
Improved modeling of new three-phase high voltage transformer with magnetic shunts
Directory of Open Access Journals (Sweden)
Chraygane M.
2015-03-01
Full Text Available This original paper deals with a new approach for the study of behavior in nonlinear regime of a new three-phase high voltage power supply for magnetrons, used for the microwave generators in industrial applications. The design of this system is composed of a new three-phase leakage flux transformer supplying by phase a cell, composed of a capacitor and a diode, which multiplies the voltage and stabilizes the current. Each cell. in turn, supplies a single magnetron. An equivalent model of this transformer is developed taking into account the saturation phenomenon and the stabilization process of each magnetron. Each inductance of the model is characterized by a non linear relation between flux and current. This model was tested by EMTP software near the nominal state. The theoretical results were compared to experimental measurements with a good agreement. Relative to the current device, the new systemprovides gains of size, volume, cost of implementation and maintenance which make it more economical.
Development of theory-based health messages: three-phase programme of formative research.
Epton, Tracy; Norman, Paul; Harris, Peter; Webb, Thomas; Snowsill, F Alexandra; Sheeran, Paschal
2015-09-01
Online health behaviour interventions have great potential but their effectiveness may be hindered by a lack of formative and theoretical work. This paper describes the process of formative research to develop theoretically and empirically based health messages that are culturally relevant and can be used in an online intervention to promote healthy lifestyle behaviours among new university students. Drawing on the Theory of Planned Behaviour, a three-phase programme of formative research was conducted with prospective and current undergraduate students to identify (i) modal salient beliefs (the most commonly held beliefs) about fruit and vegetable intake, physical activity, binge drinking and smoking, (ii) which beliefs predicted intentions/behaviour and (iii) reasons underlying each of the beliefs that could be targeted in health messages. Phase 1, conducted with 96 pre-university college students, elicited 56 beliefs about the behaviours. Phase 2, conducted with 3026 incoming university students, identified 32 of these beliefs that predicted intentions/behaviour. Phase 3, conducted with 627 current university students, elicited 102 reasons underlying the 32 beliefs to be used to construct health messages to bolster or challenge these beliefs. The three-phase programme of formative research provides researchers with an example of how to develop health messages with a strong theoretical- and empirical base for use in health behaviour change interventions.
MECHANICAL CHARACTERISTICS OF THREE-PHASE INDUCTION MOTORS WITH SINGLE-PHASE POWER SUPPLY
Directory of Open Access Journals (Sweden)
V.S. Malyar
2016-06-01
Full Text Available Aim. Development of a method for calculating mechanical characteristics of three-phase induction motors with single-phase power supply. Methods. The developed algorithm is based on the high-adequacy mathematical model of motor and projection method for solving the boundary problem for equations of electrical circuits balance presented in the three-phase coordinate system. As a result of asymmetry of power supply to the stator windings, in steady state, flux-linkage and current change according to the periodic law. They are determined by solving the boundary problem. Results. The developed mathematical model allows determining periodic dependence of coordinates as a function of slip and, based on them, mechanical characteristics of motors. Academic novelty. The developed method relies on a completely new mathematical approach to calculation of stationary modes of nonlinear electromagnetic circuits, which allows obtaining periodic solution in a timeless domain. Practical value. Using the developed calculation algorithm, one can select capacitance required to start an induction motor with single-phase power supply and calculate static mechanical characteristics at a given capacitance.
Caixeta, Cláudia E T; Cammarota, Magali C; Xavier, Alcina M F
2002-01-01
The anaerobic treatment of the wastewater from the meat processing industry was studied using a 7.2 1 UASB reactor. The reactor was equipped with an unconventional configuration of the three-phase separation system. The effluent was characterized in terms of pH (6.3-6.6), chemical oxygen demand (COD) (2,000-6,000 mg l(-1)), biochemical oxygen demand BOD5 (1,300-2,300 mg 1(-1)), fats (40-600 mg l(-1)) and total suspended solids (TSS) (850-6,300 mg l(-1)) The reactor operated continuously throughout 80 days with hydraulic retention time of 14, 18 and 22 h. The wastewater from Rezende Industrial was collected after it had gone through pretreatment (screening, flotation and equalization). COD, BOD and TSS reductions and the biogas production rate were the parameters considered in analyzing the efficiency of the process. The average production of biogas was 111 day(-1) (STP) for the three experimental runs. COD removal varied from 77% to 91% while BOD removal was 95%. The removal of total suspended solids varied from 81% to 86%. This fact supports optimal efficiency of the proposed three-phase separation system as well as the possibility of applying it to the treatment of industrial effluents.
Modeling and analysis of airlift system operating in three-phase flow
Hu, Dong; Kang, Yong; Tang, Chuan-lin; Wang, Xiao-chuan
2015-03-01
Based on the momentum theorem, the fluid governing equation in a lifting pipe is proposed by use of the method combining theoretical analysis with empirical correlations related to the previous research, and the performance of an airlift pump can be clearly characterized by the triangular relationship among the volumetric flux of air, water and solid particles, which are obtained respectively by using numerical calculation. The meso-scale river sand is used as tested particles to examine the theoretical model. Results of the model are compared with the data in three-phase flow obtained prior to the development of the present model, by an independent experimental team that used the physical conditions of the present approach. The analytical error can be controlled within 12% for predicting the volumetric flux of water and is smaller than that (±16%) of transporting solid particles in three-phase flow. The experimental results and computations are in good agreement for air-water two-phase flow within a margin of ±8%. Reasonable agreement justifies the use of the present model for engineering design purposes.
Plutonium partitioning in three-phase systems with water, granite grains, and different colloids.
Xie, Jinchuan; Lin, Jianfeng; Zhou, Xiaohua; Li, Mei; Zhou, Guoqing
2014-01-01
Low-solubility contaminants with high affinity for colloid surfaces may form colloid-associated species. The mobile characteristics of this species are, however, ignored by the traditional sorption/distribution experiments in which colloidal species contributed to the immobile fraction of the contaminants retained on the solids as a result of centrifugation or ultrafiltration procedures. The mobility of the contaminants in subsurface environments might be underestimated accordingly. Our results show that colloidal species of (239)Pu in three-phase systems remained the highest percentages in comparison to both the dissolved species and the immobile species retained on the granite grains (solid phase), although the relative fraction of these three species depended on the colloid types. The real solid/liquid distribution coefficients (K s/d) experimentally determined were generally smaller than the traditional K s/d (i.e., the K s+c/d in this study) by ~1,000 mL/g for the three-phase systems with the mineral colloids (granite particle, soil colloid, or kaolinite colloid). For the humic acid system, the traditional K s/d was 140 mL/g, whereas the real K s/d was approximately zero. The deviations from the real solid/liquid K s/d were caused by the artificially increased immobile fraction of Pu. One has to be cautious in using K s/d-based transport models to predict the fate and transport of Pu in the environment.
POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM
Directory of Open Access Journals (Sweden)
P.VASUKI,
2011-02-01
Full Text Available Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the power factor is less. To improve the power factor, the delayed current is shifted to the input voltage, through a modification of the classical sinusoidal pulse width modulation switching technique. In this way, the decrease in the phase angle between the input current and voltage is feasible, and consequently, high cost compensation capacitors can be avoided. The improvement of power factor through this switching technique on the proposed converter is investigated and verified via simulation using the software Matlab/Simulink.