Zero current switching. (ZCS). Full bridge series output series resonant dc/dcconverter ... dc/dcconverter using gate turn off devices. (a) Buck-derived. Zero- current .... showing the ripple-free input bridge current, ii. Input bus voltage. = 200Vdc, ...
A fast-response single-inductor dual-output hysteresis-current-controlled DC?DCbuck is proposed for enhancing the transient characteristics of switching DC?DCconverters and fabricated with TSMC 0.35??m DPQM CMOS processes. By adopting a hysteresis-current-controlled DC?DCbuckconverter, it is demonstrated that the hysteresis-current-controlled technique have improved dynamic response of load variations whether the load current is light or heavy. Fast-response structure achieves 5??s response with load variation which betweens 10 and 110?mA. Also proposed single-inductor dual-output structure is a time-multiplexing circuit to decrease the influence of cross regulation than that of previous designs. With a 3.6?V input power supply, the DC?DCbuckconverter precisely provides an adjustable...
Power amplifier supplied with constant supply voltage has very low efficiency in the transmitter. A DC-DCconverter in series with a linear regulator can be used to obtain voltage modulation. Since this converter should be able to change the output voltage very fast, a multiphase buckconverter with...
This paper presents a high efficiency, high switching frequency DC?DCbuckconverter in AlGaAs/GaAs technology, targeting integrated power amplifier modules for wireless communications. The switch mode, inductor load DC?DCconverter adopts an interleaved structure with negatively coupled inductors. Analysis of the effect of negative coupling on the steady state and transient response of the converter is given. The coupling factor is selected to achieve a maximum power efficiency under a given duty cycle with a minimum penalty on the current ripple performance. The DC?DCconverter is implemented in 0.5??m GaAs p-HEMT process and occupies 2??2.1?mm2 without the output network. An 8.7 nH filter inductor is implemented in 65??m thick top copper metal layer, and flip chip bonded to the DC?DC c...
The 42 VY_20°/J28 V, 175 W, 50 kHz PWM buckdc/dcconverter was operated both at room temperature ... output (load) current for continuous ... [2], to provide a design margin for the output ripple voltage .... devices such as the zero-voltage ...
The paper considers a DC-DCbuck power converter employing pulse width modulation and voltage feedback control. Global asymptotical stability of a periodical operating mode is examined. It is shown that the stability analysis can be reduced to study of a feasibility problem of semidefinite programming.
In the paper a new electrothermal average model of the diode-transistor switch operating in any dc-dcconverter is proposed. With the use of this model the non-isothermal characteristics of dc-dcconverters in the steady-state can be obtained. The method of formulation of such a model and its structure are described in detail. The correctness of the elaborated model was verified by comparing the SPICE simulated characteristics of the buck and boost converters operating both in the continuous and discontinuous conducting mode, obtained by the electrothermal dc analysis with the proposed model and by the electrothermal transient analysis with the physical models of the diode and the transistor.
This paper shows that using a recent introduced generic paralleling structure for commutation cells one can get multiple levels of total current for dc-dcconverters. This opens a new research field in power electronics area, which the paper names current multilevel converters. This new approach has been applied to a level buckconverter along with theoretical, simulated and experimental results. The application of the new concept is extended to the remainder of the dc-dcconverters following a brief discussion of particularities. As can be attained for the voltage multilevel converters the new current multilevel dc-dcconverters can be adapted to produce small harmonics content and total current sharing among the employed communication cells. (author) 12 refs., 13 figs.
The new method of formulating non-linear average electrothermal models of dc-dcconverters is presented in the paper. These models take into account both: non-linearity of diode and transistor characteristics and electrical inertia of these elements. The form of the models for buck and boost converters is presented and their correctness is verified by comparing the characteristics of the considered converters obtained with the proposed model and the classic transient analysis.
Main objective are the DC-DCconverters and the analysis of today's systems. A new topology is developed and the main DC-DCconverters are designed and simulated and the results are explained. , ?????????????? ????? DC-DC ???????????? ??????????? ??? ??????????? ??? ??????? ??? ??????????? ??? ????????...
In this work, several DC-DCconverters were designed and built. The converters are BuckBuck-Boost, Cuk, Flyback, and full-bridge zero-voltage switched. The total ionizing dose radiation and single event effects on the converters were investigated. The experimental results for the TID effects tests show that the voltages of the BuckBuck-Boost, Cuk, and Flyback converters increase as total dose increased when using power MOSFET IRF250 as a switching transistor. The change in output voltage with total dose is highest for the Buckconverter and the lowest for Flyback converter. The trend of increase in output voltages with total dose in the present work agrees with those of the literature. The trends of the experimental results also agree with those obtained from PSPICE simulation. For the full-bridge zero-voltage switch converter, it was observed that the dc-dcconverter with IRF250 power MOSFET did not show a significant change of output voltage with total dose. In addition, for the dc-dcconverter with FSF254R4 radiation-hardened power MOSFET, the output voltage did not change significantly with total dose. The experimental results were confirmed by PSPICE simulation that showed that FB-ZVS converter with IRF250 power MOSFET's was not affected with the increase in total ionizing dose. Single Event Effects (SEE) radiation tests were performed on FB-ZVS converters. It was observed that the FB-ZVS converter with the IRF250 power MOSFET, when the device was irradiated with Krypton ion with ion-energy of 150 MeV and LET of 41.3 MeV-square cm/mg, the output voltage increased with the increase in fluence. However, for Krypton with ion-energy of 600 MeV and LET of 33.65 MeV-square cm/mg, and two out of four transistors of the converter were permanently damaged. The dc-dcconverter with FSF254R4 radiation hardened power MOSFET's did not show significant change at the output voltage with fluence while being irradiated by Krypton with ion energy of 1.20 GeV and LET of 25.97 MeV-square cm/mg. This might be due to fact that the device is radiation hardened.
Fuel cell DC/DCconverters often have to be able to both step-up and step-down the input voltage, and provide a high efficiency in the whole range of output power. Conventional negative output buck-boost and non-inverting buck-boost converters provide both step-up and step-down characteristics. In this paper the non-inverting buck-boost with either diodes or synchronous rectifiers is investigated for fuel cell applications. Most of previous research does not consider the parasitic in the evaluation of the converters. In this study, detailed analytical expressions of the efficiencies for the system composed of fuel cell system and interfacing converter, considering the parasitics, are presented. It is concluded that the implementation with synchronous rectifiers provides the highest efficiency in the whole range of the fuel cell power, and its efficiency characteristic is more suitable for fuel cell applications than the implementation with diodes.
A new topology for utility-interactive, dc-ac inverters is explored. The approach is presently limited by available devices to the single-phase, 2 to 10 kW power levels typical of residential photovoltaic applications. The approach combines two of the three basic inverter operations - waveshaping and regulation - in a single dc-dcconverter stage. The output of this stage is a full-wave rectified (unipolar) sine wave. An inversion stage follows, performing the third basic inverter operation. The output is a current sine wave. This approach features unity power factor and less than 2% total current harmonic distortion. A 1-kW prototype was constructed, using a buck (down) converter for the dc-dc stage switching at approximately 20 kHz. Efficiency was generally above 90% with a peak efficiency of 94%. A cost breakdown of the prototype indicated the inverter could be built to meet the DOE cost goals for this class of inverter.
The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DCbuckconverters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buckconverter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility.
The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DCbuckconverters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buckconverter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility.
In DC/DCconverters with low output voltage and high output current, the technique of synchronous rectification is widely used for improving the output efficiency. However, SR buckconverters can experience the abnormal phenomenon called “self turn-on” which will occur in the low-side switch under some circuit conditions. “Self turn-on” is a malfunction of the low-side switch, basically caused by the resonance of the parasitic inductance and the parasitic capacitance. It results in noticeable power dissipation. In this paper, the phenomenon will be clearly described and investigated. With the theoretical analysis and the experimental verification, strategies that can suppress this phenomenon are proposed.
An interleaved pulse-width modulation (PWM) zero voltage switching (ZVS) converter is presented in this article. Two converter modules with an interleaved PWM scheme are used in the proposed circuit to achieve load current sharing and to reduce the ripple currents on the input and output capacitors such that the size of the output choke and capacitor is reduced. For each module, two buck-type dc-dcconverters with only two switches are used to reduce the current rating of transformer winding and share the load current. Two buck-type converters in each module use the same switching devices to regulate the output voltage. The ZVS turn-on of the switches is achieved by utilising the transformer leakage inductance and output capacitance of switches. Thus, the switching losses of the proposed c...
This article presents a grid-connected photovoltaic (PV) system using the classical DC-DCbuckconverter, which is responsible for stepping down the resulting voltage from several series-connected panels. Besides, the structure provides high power factor operation by injecting a quasi-sinusoidal current into the grid, with near no displacement in relation to the line voltage at the point of common coupling among the PV system and the loads. A CSI employing thyristors is cascaded with the DC-DC stage so that AC voltage results. The inverter output voltage level is adjusted by using a low-frequency transformer, which also provides galvanic isolation. The proposed system is described as mathematical approach and design guidelines are presented, providing an overview of the topology. An experi...
The photovoltaic generator exhibits a non-linear i-v characteristic and its maximum power point (MPP) varies with solar insolation. An intermediate switch-mode dc-dcconverter is required to extract maximum power from the photovoltaic array. In this paper buck, boost and buck-boost topologies are considered and a detailed mathematical analysis, both for continuous and discontinuous inductor current operation, is given for MPP operation. The conditions on the connected load values and duty ratio are derived for achieving the satisfactory maximum power point operation. Further, it is shown that certain load values, falling out of the optimal range, will drive the operating point away from the true maximum power point. Detailed comparison of various topologies for MPPT is given. Selection of the converter topology for a given loading is discussed. Detailed discussion on circuit-oriented model development is given and then MPPT effectiveness of various converter systems is verified through simulations. Proposed theory and analysis is validated through experimental investigations.
The photovoltaic generator exhibits a non-linear i-v characteristic and its maximum power point (MPP) varies with solar insolation. An intermediate switch-mode dc-dcconverter is required to extract maximum power from the photovoltaic array. In this paper buck, boost and buck-boost topologies are considered and a detailed mathematical analysis, both for continuous and discontinuous inductor current operation, is given for MPP operation. The conditions on the connected load values and duty ratio are derived for achieving the satisfactory maximum power point operation. Further, it is shown that certain load values, falling out of the optimal range, will drive the operating point away from the true maximum power point. Detailed comparison of various topologies for MPPT is given. Selection of the converter topology for a given loading is discussed. Detailed discussion on circuit-oriented model development is given and then MPPT effectiveness of various converter systems is verified through simulations. Proposed theory and analysis is validated through experimental investigations.
This paper studies switched dynamical systems based on a simplified model of two-paralleled dc-dcbuckconverters in current mode control. In the system, we present novel four switching rules depending on both state variables and periodic clock. The system has piecewise constant vector field and piecewise linear solutions: they are well suited for precise analysis. We then clarify parameter conditions that guarantee generation of stable 2-phase synchronization and hyperchaos for each switching rule. Especially, it is clarified that stable synchronization is always possible by proper use of the switching rules and adjustment of clock period. Presenting a simple test circuit, typical phenomena are confirmed experimentally.
A procedure is established for the small-signal modelling of n-connected current-programmed parallel-input/series-output pulse-width modulated bridge-based buckdc-dcconverters operating in the continuous-current conduction mode. State-space averaging is used to represent the power stage while current-mode control is modelled using a modified new continuous-time technique. Approximate analytical expressions of the major small-signal transfer functions that include the number of modules as a variable are proposed. PSpice simulations are carried out to validate the analysis.
This paper discusses the quantification of parasitic components inherent in printed circuit board (PCB) wiring, which can be of considerable value in power conversion circuits. The influence of parasitic inductance and mutual coupling are evaluated in terms of electromagnetic compatibility (EMC) for the switching operation of power MOSFETs in a dc-dcbuckconverter. The parasitic components are identified based on the partial element equivalent circuit (PEEC) method and modeled with circuit simulation. The estimated effect of the parasitic component on the switching operation of a power MOSFET is validated by comparing it with experimental results.
This paper is aimed to investigate the operating characteristics of a static synchronous compensator (STATCOM) integrated with superconducting magnetic energy storage (SMES) for high power applications in the transmission network level. The STATCOM controller topology comprises multi-level multi-pulse neutral-point clamped-type (NPC) voltage source inverters (VSIs) using the harmonics cancellation technique, and incorporates a SMES coil. An innovative two-quadrant multi-level dc-dcconverter is proposed to effectively interface the STATCOM with the superconducting coil using a buck-boost topology with neutral point voltage control capabilities; thus enabling to simultaneously control both active and reactive power exchange with the high voltage power system. A detailed analysis of major sy...
The invention provides a power system using series connected regulators. Power from a source, such as a solar array, is processed through the regulators and provided to corresponding buses used to charge a battery and supply loads. The regulators employ a bypass loop around a DC-DCconverter. The bypass loop connects a hot input of the converter to a return output, preferably though an inductor. Part of the current from the source passes through the bypass loop to the power bus. The converterbucks or boosts the voltage from the source to maintain the desired voltage at the bus. Thus, only part of the power is processed through the converter. The converter can also be used without the bypass loop to provide isolation. All of the converters can be substantially identical.
The main purpose of applying soft switching techniques to DC-DCconverters is to reduce the considerable switching losses of conventional PWM converters. There are two ways to use this benefit. One of them is to develop a converter with increased efficiency. The other one is to increase the switching frequency as to get smaller reactive components, which lets shrink the converter volume. Another reason to use soft switching techniques is the improved electromagnetic compatibility (EMC) compared with hard switching PWM converters. Most of this techniques provide softened current and voltage waveforms for the switches and diodes. In this report different techniques to reduce switching losses by using resonance are investigated. The characteristics of these techniques are compiled in tables for easier comparison. Most of the techniques are applied to a buck-type converter, simulated with parasitic effects and their key waveforms are presented. Because of the fast progress in semiconductor capabilities and the variety of applications for DC-DCconverters as well as the resonant techniques it is not possible to give a final assignment of techniques and applications. To choose the best technique for every specific application it is necessary to compare all of them. And after this, the best soft switching solution must be compared with an optimized conventional PWM converter. (author) figs., tabs., 7 refs.
The objective of this paper is to present a work concerning a digital control loop system for satellite medium power DC-DCconverters that is done in Space Research Centre. The whole control process of a described power converter bases on a high speed digital signal processing. The paper presents a development of a FPGA digital controller for voltage mode stabilization that was implemented using VHDL. The described controllers are a classical digital PID controller and a bang-bang controller. The used converter for testing is a simple model of 5-20 W, 200 kHz buck power converter. A high resolution digital PWM approach is presented. Additionally a simple and effective solution of filtering of an analog-to-digital converter output is presented.
The performance of a 42/28 V, 175 W, 50 kHz pulse-width modulated buckdc/dc switching power converter at liquid nitrogen temperature (LNT) is compared with room temperature operation. The power circuit as well as the control circuit of the converter, designed with commercially available components, were operated at LNT and resulted in a slight improvement in converter efficiency. The improvement in power MOSFET operation was offset by deteriorating performance of the output diode rectifier at LNT. Performance of the converter could be further improved at low temperatures by using only power MOSFET's as switches. The use of a resonant topology will further improve the circuit performance by reducing the switching noise and loss.
The concept of the switching cell is first introduced and utilized to study the local aspects of the switching process such as the influence of parasitic elements, switching losses, and the soft switching principle. A study is presented in order to show that this concept can be a useful tool for studying the topology of converters. It is demonstrated that from the qualitative point of view, the switching cell concept allows generalization of two principles of soft switching by dc-dcconverters at all the classic topologies, thus generating a whole family of converters. Analyses are presented of quasi-resonant switching cells using thyristors, thyristor-diodes, dual thyristors, and thyristor-dual diodes. Four topologies of non-reversible choppers are considered: buck, boost, buck-boost, and boost-buck. Above all, it is seen that the quantitative study (in particular the calculation of the natural output characteristics, the determination of constraints and consequently the design) can be conducted at the level of the single switching cell and can then be extended to different topologies. 4 refs., 16 figs., 1 tab.
The doubly fed induction generators (DFIGs) are preferred over other variable speed generators because of their advantages in terms of economy and control. One of the problems associated with high wind power penetration DFIG systems, however, is the inability of their converters to work properly under extreme low voltage conditions. This article presents a decoupled P-Q control strategy of a supercapacitor energy storage system, interfaced through a STATCOM, for low voltage ride through as well as damping enhancement of the DFIG system. The STATCOM meets the reactive power need under the depressed voltage condition, while the supercapacitor caters to the real power unbalance. An extensive dynamic model of the DFIG system including a supercapacitor DC-DCbuck-boost converter and the STATCOM...
This paper presents an advanced power converter employs a sinusoidal voltage absolute value tracking buck-boost DC-DCconverter in the first power processing stage and a polarity changing full-bridge inverter in the second stage. The proposed power conversion system has the capability of delivering good quantitative and qualitative sinusoidal output current and voltage waveforms with good output voltage regulation. Consequently, the complete voltage regulator system, which is mainly suitable for new energy generation systems as well as energy storage systems, can be constructed compactly and inexpensively without DC link electrolytic capacitor. Also, the paper presents an auxiliary passive resonant circuit for soft switching operation. Simulation results using PSIM software are presented t...
In this paper, a new method is proposed for mathematical modeling of buck-boost dc-dcconverter in continuous conduction mode (CCM). In proposed method, using the Laplace transform the relations of inductor current and output voltage are obtained. In the next step, in each switching interval using the Z-transform the initial values of inductor current and output voltage are calculated. Then, the transient and steady states responses of these quantities are calculated. In addition, the effect of the values of converter components on each of these responses is investigated. Finally, the simulation results in PSCAD/EMTDC software as well as the experimental results are used to reconfirm the validity of the theoretical analysis.
A buckDC—DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current, and it can operate with an input range of 4.5 to 30 V. At light load current, the converter operates in skip mode. The converter enters PWM mode operation with increasing load current. It reduces the switching loss at light load and standby state, which results in prolonging battery lifetime and stand-by time. Meanwhile, externally adjustable soft-start minimizes the inrush supply current and avoids the overshoot of output voltage at initial startup. The regulator is fabricated by a 0.6 ?m CDMOS process. The test results show that, under the condition of 3.3 V output, the efficiency is up to 64% at 5 mA and the maximum efficiency is 95.5%.
A buckDC-DC switching regulator with high efficiency is implemented by automatically altering the modulation mode according to load current, and it can operate with an input range of 4.5 to 30 V. At light load current, the converter operates in skip mode. The converter enters PWM mode operation with increasing load current. It reduces the switching loss at light load and standby state, which results in prolonging battery lifetime and stand-by time. Meanwhile, externally adjustable soft-start minimizes the inrush supply current and avoids the overshoot of output voltage at initial startup. The regulator is fabricated by a 0.6 {mu}m CDMOS process. The test results show that, under the condition of 3.3 V output, the efficiency is up to 64% at 5 mA and the maximum efficiency is 95.5%.
Careful inspection of efficiency in a DC-DCconverter and its dependence on different parameters have been key concerns for power electronic specialists for a long time ago. Although extensive research has been done on the estimation of power loss for different components in a DC-DCconverter separately, there isn't any comprehensive study regarding power loss analysis in a DC-DCconverter. In this research, detailed description and necessary considerations in order to analyze the power loss of all components in a Push-Pull DC-DCconverter are presented. Push-Pull topology is the best choice for investigating efficiency issues, since it exhibits all different types of power loss that are usually encountered in DC-DCconverters. This research proposes and verifies appropriate power loss models for all components in a DC-DCconverter that dissipate power. For this purpose, conduction and switching loss models of all the relevant components are fully developed. The related equations are implemented in MATLAB environment to simulate all possible causes of power loss in the converter. In order to provide a test bed for evaluation of the proposed loss models and the converter efficiency, a 50W Push-Pull DC-DCconverter was designed and implemented. The experimental results are in full accordance with the simulation results in different input voltages, load conditions and switching frequencies. It was finally shown that the proposed models accurately estimate the DC-DCconverter's efficiency.
We present in this thesis a study of a class of photovoltaic system by a bond graph approach. This study concerns the modelling, the analysis and the control of some configurations including PV generator, DC/DCconverters and DC motor-pumps. The modelling of the different elements of a photovoltaic system is an indispensable stage that must precede all application of sizing, identification or simulation. However, theses PV systems are of hybrid type and their modelling is complex. It is why we use a unified modelling approach based on the bond graph technique. This methodology is completely systematic and has a sufficient flexibility for allowing the introduction of different components in the system. In the first chapter, we recall the principle of functioning of a photovoltaic generator and we treat mainly the MPPT (Maximum Power Point Tracking) working. In the second chapter, we elaborate bond graph models of various photovoltaic system configurations. For the PV source, we elaborate, in a first stage, a complete model taking into account the various physical phenomena influencing the quality of the PV source. In a second stage, we deduce a reduced bond graph model more easy to use for analysis and control purposes. For the DC/DCconverters, we recall the bond graph modelling of switching elements and the average bond graph of the DC/DCconverters developed in the literature. Thus, we deduce the bond graphs models of the various DC/DCconverters to be used. The third chapter presents a dynamic study of some configurations stability in linear procedure. In the fourth chapter, we study the feasibility of non linear controllers by input/output linearization for some configurations of PV systems. In this study, we use the concept of inverse bond graph to determine, by a bond graph approach, the expression of the control input and the nature of the stability of the internal dynamics (dynamics of zeros). The fifth chapter is dedicated for the presentation of some experimental results. These results are relative to the achieved experimental devices: characterization system for photovoltaic modules and fields; photovoltaic system using a PV generator coupled to a DC motor-pump through a buckconverter. This system uses a non linear control for MPPT running. (authors)
For the improved three-level (TL) buck direct current-direct current (DC-DC) switching converter which is a high-order, discrete, non-linear, and time-variant dynamic system, the work multi-modalities and principle are analyzed, and the state space equation model is established by introducing the switch cycle averaging operator under low-frequency, small ripple, and small-signal assumption. The transfer function from control to output that is needed by closed-loop feedback system is deduced by introducing small-signal perturbation. The closed-loop control system is designed based on the transfer function model by applying feedback control theory. The experiment results show that closed-loop system has good dynamic and static performance, and further indicates that the mathematic models are...
A small-scale photovoltaic (PV) powered reverse osmosis (RO) plant is designed to operate at variable flow/pressure conditions for stand-alone applications in equatorial areas to desalinate brackish water. Two operation strategies for a PV array of 165 Wp (3 modules of 55 Wp) are simulated and compared: Plant 1 uses two modules for the RO pump and one module for the well pumping; Plant 2 uses the three modules for both applications. A DC?DCbuckconverter with maximum power point tracking (MPPT) was developed especially for Plant 2. Results show that Plant 2 has a better performance, such as: increase of 60% in the daily permeate production and of 32% in the daily operation period, 1.57 kWh.m?3 of average specific energy consumption and a PV power-permeate daily production rate of 0.64 Wp....
The historically high cost of crude oil price is stimulating research into solar (green) energy as an alternative energy source. In general, applications with large solar energy output require a maximum power point tracking (MPPT) algorithm to optimize the power generated by the photovoltaic effect. This work aims to provide a stand-alone solution for solar energy applications by integrating a DC/DCbuckconverter to a newly developed quadratic MPPT algorithm along with its appropriate software and hardware. The quadratic MPPT method utilizes three previously used duty cycles with their corresponding power outputs. It approaches the maximum value by using a second order polynomial formula, which converges faster than the existing MPPT algorithm. The hardware implementation takes advantage ...
Abstract A fuel cell-based power systems emulator designed to test devices and loads intended to interact with real prototypes is presented. The emulator uses a digital processing device and electrical power systems, evaluating the impact of using either switching or linear power stages in the emulator capabilities. A real fuel cell prototype is emulated using a parameterized physical fuel cell model, which is computed online by a digital device. Also, several power stages not previously used specifically for this application, with different efficiencies and performances, were developed and analysed. One of the power stages was based on a two-inductor step-down DC/DCconverter for a switching power stage instead of the classical buck structure that is more prone to duty cycle saturation in...
Many Embedded Systems are indeed Software Based Control Systems (SBCSs), that is control systems whose controller consists of control software running on a microcontroller device. This motivates investigation on Formal Model Based Design approaches for automatic synthesis of SBCS control software. We present an algorithm, along with a tool QKS implementing it, that from a formal model (as a Discrete Time Linear Hybrid System, DTLHS) of the controlled system (plant), implementation specifications (that is, number of bits in the Analog-to-Digital, AD, conversion) and System Level Formal Specifications (that is, safety and liveness requirements for the closed loop system) returns correct-by-construction control software that has a Worst Case Execution Time (WCET) linear in the number of AD bits and meets the given specifications. We show feasibility of our approach by presenting experimental results on using it to synthesize control software for a buckDC-DCconverter, a widely used mixed-mode analog circuit.
Many Embedded Systems are indeed Software Based Control Systems (SBCSs), that is control systems whose controller consists of control software running on a microcontroller device. This motivates investigation on Formal Model Based Design approaches for automatic synthesis of SBCS control software. In previous works we presented an algorithm, along with a tool QKS implementing it, that from a formal model (as a Discrete Time Linear Hybrid System, DTLHS) of the controlled system (plant), implementation specifications (that is, number of bits in the Analog-to-Digital, AD, conversion) and System Level Formal Specifications (that is, safety and liveness requirements for the closed loop system) returns correct-by-construction control software that has a Worst Case Execution Time (WCET) linear in the number of AD bits and meets the given specifications. In this technical report we present full experimental results on using it to synthesize control software for two versions of buckDC-DCconverters (single-input and ...
Much research has been done on resonance techniques, particularly in the field of DC/DC power conversion, which allow converters to operate at high frequencies. The focus of this thesis is the series resonant converter operating above its resonance freque...
An analog maximum power point tracking (MPPT) circuit for a thermoelectric generator (TEG) is proposed. We show that the peak point of the voltage conversion gain of a boost DC-DCconverter with an input voltage source having an internal resistor is the maximum power point of the TEG. The key characteristic of the proposed MPPT controller is that the duty ratio of the input clock pulse to the boost DC-DCconverter shifts toward the maximum power point of the TEG by seeking the peak gain point of the boost DC-DCconverters. The proposed MPPT technique provides a simple and useful analog MPPT solution, without employing digital microcontroller units.
An analog maximum power point tracking (MPPT) circuit for a thermoelectric generator (TEG) is proposed. We show that the peak point of the voltage conversion gain of a boost DC?DCconverter with an input voltage source having an internal resistor is the maximum power point of the TEG. The key characteristic of the proposed MPPT controller is that the duty ratio of the input clock pulse to the boost DC?DCconverter shifts toward the maximum power point of the TEG by seeking the peak gain point of the boost DC?DCconverters. The proposed MPPT technique provides a simple and useful analog MPPT solution, without employing digital microcontroller units.
The study of multi-state dc-dc power conversion techniques is restricted by the complicated inner switching behaviors. This paper presents a general and unified transient analysis for various sorts of multi-state dc-dcconverters from a viewpoint of their system energy characteristics. With the applications to the boost converters, the proposed analytical method has indicated its advantages of high convenience and practicability to the multi-state converters. The generalized concepts of system energy parameters of dc-dcconverters are introduced and applied to the transient analysis. Consequently, the expressions of system model parameters of multi-state dc-dcconverters are deduced. The new 2nd order transfer functions are obtained to describe the large- and small-signal mathematical mode...
Aiming an IC implementation of a DC-DCconverter which can provide a 4.5˜5 V stepped-up voltage for diode-lamps, a switched-capacitor (SC) DC-DCconverter is proposed in this paper. Different from a conventional approach employing doubler circuits, the proposed circuit provides the output voltage by achieving a 3/2 step-up conversion. Therefore, decline in power efficiency for the proposed circuit is gentle. The process of DC-DC conversion is analyzed theoretically. To confirm the validity of the circuit design, SPICE simulations are performed. For the input voltage 3.2˜4.5 V, the power efficiency is 73˜92 % in the output current about 150 mA.
the maximum output voltage of the DC-DCconverter. For example ... the input, and yet only use switching and filtering components ... zero volts, allowing operation as a current limiting .... operation in the CL mode to reduce the current ripple.
A Nonlinear Model for Designing Herschel-Quincke Waveguide Arrays to Attenuate Shock Waves from Transonic Turbofan Engines ..... Decentralized Nonlinear Controller Based SiC Parallel DC-DCConverter ... Mary Pate ( 281 ) 292 - 9903 ...
Modern control theories such as fuzzy control, sliding-mode control, optimal control, neural network control have been widely used in discrete-switching DC?DCconverters, While they are seldom used in monolithic integration. Under parameter variation, large supply and load disturbance, high slew-rate current transient, high nonlinearity in today and future power management integrated circuits, linear control theories used in traditional monolithic DC?DCconverters cannot satisfy required performance, which make it stringent to use modern control theories in monolithic DC?DCconverters. This paper proposes cascade controller which consists of PWM based sliding-mode-voltage control and current-mode control for high frequency DC?DCconverters. As long as the dynamic responses of the inner cur...
CLOSED?LOOP?CONTROLLED HIGH VOLTAGE DC?DCCONVERTER. ... power supply for a space electric propulsion system [1], with the added capability of ... This cryogenic beam supply was previously tested in terms of efficiency, output ...
Feb 23, 2006 ... The utilization of power electronics designed for and operated at low ... This would also result in reduced development time-and-effort and launch ... (PWM) controllers, and advanced commercial DC/DCconverter modules.
If a duty ratio, a load resistance and an input voltage in a boost DC-DCconverter are changed, the dynamic characteristics are varied greatly, that is, the boost DC-DCconverter has non-linear characteristics. In many applications of the boost DC-DCconverters, the loads cannot be specified in advance, and they will be changed suddenly from no load to full load. In the boost DC-DCconverter, a conventional single controller cannot be adapted to change dynamics and it occurs large output voltage variation. In this paper, an approximate 2-degree-of-freedom (A2DOF) digital controller for suppressing the change of step response characteristics and the variation of an output voltage in load sudden change is proposed. Experimental studies using a micro-processor for the controller demonstrate that this type of digital controller is effective to suppress the variations of the output voltages.
The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into the specifications. Based on these two documents, a set of 23 topologies was analysed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies were in further investigated by means of an initial design-iteration and simulations. Based on the results achieved in, an updated document (this) is created. The items of interest in this report are efficiency and component ratings (magnetics, transistors, diodes and capacitors). The topologies investigated in this report are: the normal full bridge DC/DCconverter, the MOHAN DC/DCconverter, the normal full bridge DC/AC inverter, and the modified SHIMIZU DC/AC inverter. The simulations carried out in this report reveals that the efficiencies for the two DC/DCconverters (together with the DC/AC inverter) are much similar to each other {approx} 72%. For that reason, none of them can be preferred above the other. On the other hand, when counting the components and estimating the cost for the two DC/DCconverter, the standard full bridge DC/DCconverter (cost: {approx} 197 DKk.) seems to be most advantageous that the MOHAN DC/DCconverter (cost: {approx} 213 DKk.). The modified SHIMIZU inverter seems to be better, in terms of efficiency, than the two mentioned DC/DCconverters together with the DC/AC inverter. During the design stage of this inverter, it emerged that the control circuit could be a limiting factor in terms of speed and accuracy. A deeper investigation should be carried out in order to state a more adequate conclusion about this novel inverter. The recommendation for the future is; to base the SolcelleInverter on the standard full bridge DC/DCconverter together with the standard full bridge DC/AC inverter, and the modified SHIMIZU DC/AC inverter should also be further investigated. (au)
In this paper, an improved Zero-Voltage-Transition PWM DC/DCconverter topology is proposed. The proposed ZVT PWM DC/DCconverter has an advantage of zero-voltage and zero-current switching of the auxiliary switches. The ZVS and ZCS operations can be achieved by using the saturable inductor and auxiliary capacitor. The operation principles are explained in detail and the validity of the proposed circuit is verified by the simulation results. (author). refs., figs.
A compact DC-DC convertor is proposed and fabricated in multilayer ferrite substrate using LTCC technology. The spiral conductors are buried into the ferrite substrate with a multilayer 3-D structure to reduce the volume of convertor. The passive integration of magnetic components and surface circuitry are achieved in a whole substrate and the size of module can be reduced markedly. The whole height of module is only 3mm, 1/3 of the height of conventional modules. Testing results indicate that the performance of the module is excellent in Point-of-Load (POL) field. The step-down DC-DCconverterconverts input voltage of 5V to output voltage of 3.3V. It is confirmed that the maximum conversion efficiency of 93.2% is sufficient for actual DC-DCconverter application. Such a compact DC-DC convertor provides a compact, low cost and high reliability approach for power supply and magnetic integration application.
This paper presents the bidirectional converter interface for a 6 kV battery energy storage test bench. The power electronic interface consists a two stage converter topology having a low voltage dc-ac grid connected converter and a new dual active bridge dc-dcconverter with high transformation ratio. The dc-dcconverter controls the battery charge/discharge current while the grid converter controls the common dc-link voltage and the grid current. The applied control structures and the hardware implementation of both converters are presented, together with their interaction. Experimental results of the test bench show good performance for the bidirectional power flow with a maximum operating power of 100 kW.
A power converter includes a boost converter, a DC/DCconverter and a coupler chain. The boost converter receives a rectified AC input and generates a high voltage output. The boost converter includes a zero-voltage-switching transistor that is operable to adjust the power factor of the rectified AC...
Hybrid electric vehicles (HEVs) offer many advantages, such as high fuel economy, low emissions, and silent operation. In HEVs, there are two or more different voltage buses for different purposes of the vehicle operation. There are needs of galvanically isolated bidirectional DC-DCconverter to link different DC voltage bus and transfer energy back and forth. For example, one of the DC-DCconvertersconvert the high voltage (200-300V) in the main battery to low voltage (-12V) for use in electrical equipment, while the other converts 300V battery voltage and supply the drive motor with 500V. High efficiency, compact size, lightweight, and reliability are all essential requirements for DC-DCconverters for electric and hybrid vehicles. This paper introduces a bidirectional, isolated DC-DCconverter for medium power applications. A dual full-bridge topology is developed to achieve the power rating. A 1kW prototype of the converter has been built and tested. The experimental results of the converter's steady state operation confirm the simulation analysis. This converter is a first step to understanding the design and build of a medium power DC-DCconverter.
Powering terminal should prevent signal inflow from the communication lines. Powered terminal in most wire communication systems needs to separate ac signals and dc supply power in its input part connected to the communication lines. Our original communication system consists of low-power dc-dcconverters. In our system, the direction of dc power is opposite in powering terminal at reception and powered terminal. Therefore, to use the same electronic choke for powering terminal and powered terminal, it is preferable that the electronic choke be bidirectional. So, we have proposed new electronic choke by the use of small inductors and an amplifier. From the viewpoint of power distribution, this system contains a parallel-connected dc power supply. In this paper, voltage-ripple attenuation characteristics at reception are presented on the dc power distribution system using buck-type converters and new electronic chokes. New electronic choke has an ability of good attenuation against signals. Even though switching frequencies are different, no beat is observed in the output dc voltage waveform of powered terminal. New electronic choke effectively removes circulation or interference by the ripple.
This paper presents an adaptive terminal sliding mode control (ATSMC) strategy for DC-DCbuckconverters. The idea behind this strategy is to use the terminal sliding mode control (TSMC) approach to assure finite time convergence of the output voltage error to the equilibrium point and integrate an adaptive law to the TSMC strategy so as to achieve a dynamic sliding line during the load variations. In addition, the influence of the controller parameters on the performance of closed-loop system is investigated. It is observed that the start up response of the output voltage becomes faster with increasing value of the fractional power used in the sliding function. On the other hand, the transient response of the output voltage, caused by the step change in the load, becomes faster with decreasing the value of the fractional power. Therefore, the value of fractional power is to be chosen to make a compromise between start up and transient responses of the converter. Performance of the proposed ATSMC strategy has been tested through computer simulations and experiments. The simulation results of the proposed ATSMC strategy are compared with the conventional SMC and TSMC strategies. It is shown that the ATSMC exhibits a considerable improvement in terms of a faster output voltage response during load changes. PMID:22877744
This study investigates multiple levels of impedance-matching methods for piezoelectric energy harvesting in order to enhance the conversion of mechanical to electrical energy. First, the transduction rate was improved by using a high piezoelectric voltage constant (g) ceramic material having a magnitude of g33 = 40 x 10(-3) V m/N. Second, a transducer structure, cymbal, was optimized and fabricated to match the mechanical impedance of vibration source to that of the piezoelectric transducer. The cymbal transducer was found to exhibit approximately 40 times higher effective strain coefficient than the piezoelectric ceramics. Third, the electrical impedance matching for the energy harvesting circuit was considered to allow the transfer of generated power to a storage media. It was found that, by using the 10-layer ceramics instead of the single layer, the output current can be increased by 10 times, and the output load can be reduced by 40 times. Furthermore, by using the multilayer ceramics the output power was found to increase by 100%. A direct current (DC)-DCbuckconverter was fabricated to transfer the accumulated electrical energy in a capacitor to a lower output load. The converter was optimized such that it required less than 5 mW for operation. PMID:17941391
Power converters capable of operation at cryogenic temperatures are anticipated to play an important role in the power system architecture of future NASA deep space missions. Design of such converters to survive cryogenic temperatures will improve the power system performance and reduce development and launch costs. Aerospace power systems are mainly a DC distribution network. Therefore, DC/DC and DC/AC converters provide the outputs needed to different loads at various power levels. Recently, research efforts have been performed at the NASA Glenn Research Center (GRC) to design and evaluate DC/DCconverters that are capable of operating at cryogenic temperatures. This paper presents a summary of the research performed to evaluate the low temperature performance of five DC/DCconverters. Various parameters were investigated as a function of temperature in the range of 20 to -196 C. Data pertaining to the output voltage regulation and efficiency of the converters is presented and discussed.
This paper presents a high-efficiency grid-connected photovoltaic (PV) module integrated converter (MIC) system with reduced PV current variation. The proposed PV MIC system consists of a high-efficiency step-up DC-DCconverter and a single-phase full-bridge DC-AC inverter. An active-clamping flyback converter with a voltage-doubler rectifier is proposed for the step-up DC-DCconverter. The proposed step-up DC-DCconverter reduces the switching losses by eliminating the reverse-recovery current of the output rectifying diodes. To reduce the PV current variation introduced by the grid-connected inverter, a PV current variation reduction method is also suggested. The suggested PV current variation reduction method reduces the PV current variation without any additional components. Moreover, for centralized power control of distributed PV MIC systems, a PV power control scheme with both a central control level and a local control level is presented. The central PV power control level controls the whole power production by sending out reference power signals to each individual PV MIC system. The proposed step-up DC-DCconverter achieves a high-efficiency of 97.5% at 260 W output power to generate the DC-link voltage of 350 V from the PV voltage of 36.1 V. The PV MIC system including the DC-DCconverter and the DC-AC inverter achieves a high-efficiency of 95% with the PV current ripple less than 3% variation of the rated PV current. (author)
This paper presents a high-efficiency grid-connected photovoltaic (PV) module integrated converter (MIC) system with reduced PV current variation. The proposed PV MIC system consists of a high-efficiency step-up DC-DCconverter and a single-phase full-bridge DC-AC inverter. An active-clamping flyback converter with a voltage-doubler rectifier is proposed for the step-up DC-DCconverter. The proposed step-up DC-DCconverter reduces the switching losses by eliminating the reverse-recovery current of the output rectifying diodes. To reduce the PV current variation introduced by the grid-connected inverter, a PV current variation reduction method is also suggested. The suggested PV current variation reduction method reduces the PV current variation without any additional components. Moreover, ...
This paper presents a hysteretic (sliding mode) control IC for a buckDC/DCconverter for use as an envelope tracking power supply to increase the efficiency of an RF power amplifier. The IC integrates a high-bandwidth error amplifier, a comparator with hysteresis, and a high-side driver for an external N-channel power MOSFET. The total control loop delay using the implemented IC is 35ns, this is shown to be a 30% reduction compared to a state-of-the-art discrete IC based solution. The presented results also show that it is viable to integrate a 100MHz operational amplifier on the same die as a high-voltage MOSFET driver operating with slew rates in excess of 5V/ns. The IC is demonstrated in a tracking power supply with 30W output power and 3?s rise/fall time, running from a 40V input. The complete IC, including pads, takes up 4mm2 in a 0.35?m 50V CMOS process.
To reduce the supply current distortions and low power factor operations with a conventional diode bridge rectifier connected to the utility system, a novel three-phase single-way rectifier is presented in the paper. The circuit configuration is based on the buck-boost DC-DCconverter, in which AC flyback inductors play a role of the energy storage/transfer. If the simple pulse width modulation with uniform duty factor is introduced and if the rectifier operates in discontinuous current conduction mode, the supply currents can be sinusoidally waveshaped with a near unity power factor. Moreover, the step-up/step-down characteristics of the output voltage can easily be obtained by appropriately adjusting the duty factor of the switches. The experimental setup, employing insulated-gate bipolar transistors as the power switching devices, is implemented and the state-space method is introduced to predict the voltage and current waveforms and steady-state characteristics. The experimental and simulated results confirm the relevance of the presented circuit configuration as an useful rectifier with sinusoidal supply currents and step-up/down output voltage regulation. 9 refs., 8 figs., 1 tab.
The performance test of four different martial lead acid (Li-Acid), Nickel cadmium (Ni-Cd), lithium-ion (Li-Ion) and nickel metal hydride (NiMH) batteries for 4WD electric vehicle under several speeds variation constraints are presented in this paper. The battery materials model choice is a key item, and thanks to an increasing importance on vehicle range and performance, the Li-Acid, Ni-Cd,Li-Ion and NiMH batteries could become a viable candidate that's our proposal battery model in the present work , in this way the present paper show a novel strategy of 4WD electrical vehicle power electronics studies when the current battery take into account the impact of the direct torque based space vector modulation technique (DTC-SVM) in the several speed variations using the primitive battery SOC of 75 % state. The speed of four wheels is calculated independently during the turning with the electronic differential system computations which distributes torque and power to each in-wheel motor according to the requirements, adapts the speed of each motor to the driving conditions This paper focuses lead acid ,Lithium-ion and NiMH Batteries controlled by Buck Boost DC-DCconverter power supply for EV. The performances of the proposed strategy controller give a satisfactory simulation results. The proposed control law increases the utility EV autonomous under several roads topologies.
This paper uses compact models of power electronics converters to represent their EMC behavior. The model does not need any knowledge of the converter design since it is identified from external measurements. Three different DC-DCconverters will be identified and the model validated in various netw...
In this research, the converter rectifier unit of the inverter air conditioner is substituted into the bidirectional PWM converter. The DC/DC power converter is established on the DC link between the photovoltaic array and the inverter air conditioner, and the photovoltaic air conditioning system which can be parallel driven which utility is developed. (author). 35 ref., 112 figs.
We present data on the vulnerability of a variety of candidate spacecraft electronics to proton and heavy-ion induced single-event effects and proton-induced damage. Devices tested include optoelectronics, digital, analog, linear bipolar, hybrid devices, Analog-to-Digital Converters (ADCs), Digital-to-Analog Converters (DACs), and DC-DCconverters, among others.
Main inverter • Power. • Battery charge/ converts processor discharge. 160 Vdc. • Remote ..... requiring a mix of transformers, converters, ..... PARTIAL. AR RAY. SHUNT. SOUTH. ARRAY. DRIVE. ELECTRONICS u. J". _. 100V. BU_ .... to detect ground fault. Dc/dcconverters are used to interface with loads. A Navy standard, ...
The development at CERN of low noise DC-DCconverters for the powering of front-end systems enables the implementation of efficient powering schemes for the physics experiments at the HL-LHC. Recent tests made on the ATLAS short strip tracker modules confirm the full electromagnetic compatibility of the DC-DCconverter prototypes with front-end detectors. The integration of the converters in the trackers front-ends needs to address also the material budget constraints. The impact of the DC-DCconverters onto the material budget of the ATLAS tracker modules is discussed and mass reduction techniques are explored, leading to a compromise between electromagnetic compatibility and mass. Low mass shield implementations and Aluminum core inductors are proposed. Also, the impact on emitted noise due to a size reduction of critical components is discussed. Finally, material reduction techniques are discussed at the board layout and manufacturing levels.
The aim of the article is design of DC/DCconverter and discussing of problematic supply using electric power splitter. The electric power splitter with AC/DC converter is source for the DC/DCconverter, which is dedicated for charging and discharging of hybrid car drive super-capacitor energy storage. The electric power splitter is synchronous machine with two rotating parts. First rotor contains permanent magnet and the second rotor contains three-phase windings. The amplitude of output voltage depends on difference between first and second rotor speed. The main role of the DC/DCconverter is to optimize energy content in super-capacitor storage used to acceleration and deceleration driving period of the passenger car with hybrid electric vehicle (HEV) drive system using electric power splitter.
The conventional three-level high frequency phase-shifted dc/dcconverter has a disadvantage that a circulating current flows through transformer and switching devices during the freewheeling interval. Due to this circulating current and RMS current stress, conduction losses of transformer and switching devices increases. To alleviate these problems, we propose an improved three-level Zero Voltage and Zero Current Switching (ZVZCS) dc/dcconverter using a tapped inductor, a snubber capacitor and two snubber diodes attached at the secondary side of transformer. The proposed ZVZCS converter in verified on a 7kW, 30Hz experimental prototype. (author). 5 refs., 9 figs.
Simplifying the composition of the automotive HID lamp electronic ballast has been considered. This paper describes the novel electronic ballast that is composed of a DC/DCconverter, a capacitor connected to a lamp in series, a switch (S3) connected to the capacitor in parallel, a switch (S2) placed between the output terminals of the DC/DCconverter and also connected in parallel to the lamp and the capacitor in series, and an igniter. All MOSFETs (S1 in the DC/DCconverter, S2 and S3) in the ballast are operated on the common voltage position (GND) of the circuit. The DC/DCconverter is operated intermittently and the operation of S2 synchronizes with the operation of it to supply the lamp with an alternate square wave voltage. Operating an automotive HID lamp succeeded using the novel ballast and by setting some issues below. 1) The occurrence of the power loss when S2 is turned on. 2) The occurrence of extinction of gas discharge. This paper describes how the loss can be decreased if a part of the energy stored in the output capacitor of the DC/DC conveter is used to operate the lamp before S2 is turned on. It also describes how an inductor and a capacitor were added to the proposed electronic ballast to raise the lamp voltage in order to prevent the current from disappearing.
This study focused on three simplified models, namely (1) one set of single-phase DC-DCconverter, (2) two sets of parallel connection single-phase DC-DCconverter, and (3) two sets of series connection single-phase DC-DCconverter. The purposes are: (1) to propose the simplification conditions and procedures for the three-phase AC-DC converter; (2) propose a set of new simplification steps for modeling, and present the examples of different three-phase AC-DC circuit topologies, detailed discussion on the simplification steps for modeling of a three-phase AC-DC converter is offered, to help people simplify and analyze the simplified model easily; (3) according to three types of simplified modeling in the three-phase AC-DC converter, this study established a useful reference for the design and analysis of the control systems of the three-phase AC-DC converter simply; (4) to acquire PWM control strategy beforehand based on PFC-Controlled property; (5) to reduce the switching loss for the PWM control strategy of the simplified model; (6) to maintain the original circuit topology and verify that the theory can extensively apply the knowledge of single-phase DC-DCconverter to the simplified modeling of three-phase AC-DC converter.
One solution to the low specific power of hybrid electric vehicular batteries is a hybrid energy storage system (HESS) that takes advantage of the high specific power performance of ultra-capacitors. The design of a type of zero current transition (ZCT) soft switching bidirectional direct current-direct current (DC-DC) power converter that can be used as an ultra-capacitor-battery interface in an active parallel schema of a HESS is described. The circuit operation of the ZCT DC-DC power converter is depicted in detail. The HESS controller is designed as a two-layered hierarchical control structure: the first layer is responsible for working mode control of the HESS, and the second layer is responsible for DC-DC power converter control in which a fuzzy logic PID algorithmis employed. Simula...
A novel zero current soft-switching (ZCS)-PWM cell-assisted half-bridge DC-DCconverter topology with a high frequency link is proposed in this paper. The newly-proposed DC-DCconverter consists of a PWM-controlled single-ended half-bridge high frequency (HF) inverter and a current doubler rectifier linked with a HF transformer. In order to attain the wide range of ZCS-PWM operation in the primary-side HF inverter, an active edge resonant snubber cell composed by a switched capacitor and a lossless inductor is adopted in the half-bridge leg, providing ZCS commutation for a wide range of output power. The operation characteristics of the DC-DCconverter proposed here are described, and its feasibility data is demonstrated and evaluated with simulation and experimental results.
This article describes a direct current (DC) isolated network that is infed with distributed generation from renewable sources and cogeneration units. The sources are connected to the network via DC/DCconverters to keep the voltage within a defined range and to ensure the required power flow. The consumption is directly connected to the DC network, without any DC/DCconverter. The storage is located at a single point in the network. A simulation analysis based on a DC-network model shows that it is possible to operate a DC network with standard elements used for the generation side as well as for the consumption side. The key elements are the DC/DCconverters, which control the voltage of the network and optimize the operation of the sources. (author)
In this paper, an analytical technique is presented for time domain analysis (transient and steady-state response) of perturbed PWM push-pull DC-DCconverter using interesting corollary on Kharitonov?s theorem. The main advantage of the proposed analysis is that even though the transfer function model of a PWM push-pull DC-DCconverter is perturbed, the complete analysis has been done on a linear transfer function model of a PWM push-pull DC-DCconverter. The proposed analysis is verified using MATLAB simulation. This analysis will be very much useful to power electronics engineers, since the technique is very simple and computationally efficient and easily applicable in precise applications such as aerospace applications.
In this paper, a novel switched-capacitor DC-DCconverter with pulse density and width modulation (PDWM) is proposed with reduced output ripple at variable output voltages. While performing pulse density modulation (PDM), the proposed PDWM modulates the pulse width at the same time to reduce the output ripple with high power efficiency. The prototype chip was implemented using 65nm CMOS process. The switched-capacitor DC-DCconverter has 0.2-V to 0.47-V output voltage and delivers 0.25-mA to 10-mA output current from a 1-V input supply with a peak efficiency of 87%. Compared with the conventional PDM scheme, the proposed switched-capacitor DC-DCconverter with PDWM reduces the output ripple by 57% in the low output voltage region with the efficiency penalty of 2%.
The Capacitor Coupled Converter (Ccc) Is A Dc-DcConverter Which Produce A Dc Source As The Output. It Has Two Input Terminals For Connection To A Dc Voltage Source, Two Output Terminals For Connection To A Load, And A Plurality Of Circuit Control Terminals For Receiving A Plurality Of Control Wavef...
High voltage transistors in DC-DCconverters are prone to catastrophic Single Event Burnout in the LHC radiation environment. This paper presents a systematic methodology to analyze single event effects sensitivity in converters and proposes solutions based on de-rating input voltage and output current or voltage.
An AC/DC power converter includes a pair of input terminals, a boost unit, a DC/DCconverter, a coupler chain, and a discharge chain. The pair of input terminals connect to a pulsating DC source. The boost unit is coupled to the input terminals and generates a voltage higher than the voltage at the ...
In this thesis a predefined design parameters are used to present theoretical guidelines for design of low voltage, and low power DC-DCconverter with high power efficiency and low levels of EMI (Electro-Magnetic Interference). This converter is used to alter the DC voltage supplied by the power sou...
Very small manually wound transformers for subwatt dc-dcconverters are notorious for their relatively high cost and low reliability. In this paper, an isolated low-profile low-power 8 MHz soft-switching power converter using a coreless printed circuit board (PCB) transformer is described. Coreless ...
We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders the feasible introduction of this equipment in undergraduate laboratories.
An asymmetrical duty-cycle dc-dc power converter was proposed recently, which allows zero-voltage switching while keeping the switch conduction losses as low as in standard hard switched PWM converters. Further developments now allow the asymmetrical circuit to exhibit lower conduction losses than standard PWM circuits.
This paper shows the analysis and implementation of a hybrid DC–DC power converter. The proposed topology consists of a series linear voltage regulator in parallel with a switching step-down converter. This topology can provide small ripple at the output voltage, fast responses for load variations a...
A novel technique for efficiently extracting the maximum output power from a solar panel under varying meteorological conditions is presented. The methodology is based on connecting a pulsewidth-modulated (PWM) DC/DC SEPIC or Cuk converter between a solar panel and a load or battery bus. The convert...
In this paper, an ultra-low voltage and power DC/DCconverter is presented. This converter harvests energy from a Microbial Fuel Cell (MFC) in order to feed another circuit such as an autonomous wireless sensor. The MFC behaves as a voltage generator of 475mV open-circuit voltage with a 600? serial ...
The research reported in this dissertation focuses on the development of optimization tools for the design of subsystems in a modern aircraft power distribution system. The baseline power distribution system is built around a 270V DC bus. One of the distinguishing features of this power distribution system is the presence of regenerative power from the electrically driven flight control actuators and structurally integrated smart actuators back to the DC bus. The key electrical components of the power distribution system are bidirectional switching power converters, which convert, control and condition electrical power between the sources and the loads. The dissertation is divided into three parts. Part I deals with the formulation of an optimization problem for a sample system consisting of a regulated DC-DCbuckconverter preceded by an input filter. The individual subsystems are optimized first followed by the integrated optimization of the sample system. It is shown that the integrated optimization provides better results than that obtained by integrating the individually optimized systems. Part II presents a detailed study of piezoelectric actuators. This study includes modeling, optimization of the drive amplifier and the development of a current control law for piezoelectric actuators coupled to a simple mechanical structure. Linear and nonlinear methods to study subsystem interaction and stability are studied in Part III. A multivariable impedance ratio criterion applicable to three phase systems is proposed. Bifurcation methods are used to obtain global stability characteristics of interconnected systems. The application of a nonlinear design methodology, widely used in power systems, to incrementally improve the robustness of a system to Hopf bifurcation instability is discussed.
This paper presents a DC/DCconverter topology for renewable energy systems. The proposed DC/DCconverter can be used to obtain a well-regulated output voltage from low-voltage power source, such as wind turbine, photovoltaic array, fuel cell, etc. It has the merits of high efficiency, low device stresses, and low current ripple. The operating principle, theoretical analysis, and design criteria are provided in this paper. A laboratory prototype was successfully implemented. The simulation and experimental results are given to verify the feasibility of the proposed scheme. Copyright Copyright 2008 John Wiley & Sons, Ltd.
P-type low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) integrated driver circuits are proposed for low-cost chip-on-glass (COG) panel. In order to reduce the process cost of panel, gate driver employing level-shifter, shift register and DC–DCconverter is integrated by p-type polycrystalline silicon (poly-Si) TFTs. The gate drivers are composed of the level-up and level-down voltage shifters and the robust two-clock shift registers. The DC–DCconverters are designed using diode-connected type charge pumps and regulators. The proposed p-type circuits were verified successfully by the simulations and the measurements.
Analysis and modeling of common mode conducted ElectroMagnetic Interference (EMI) in the Radio Frequency (RF) range (10 KHZ--30MHZ) of a ZVT (DC-DC boost Zero Voltage Transition) PWM converter and a conventional PWM (DC-DC boost) converter are compared. Noise signal measurement is carried out by means of a LISN (Line Impedance Stabilization Network). To compute the noise spectrum of LISN output in RF range, direct simulation of equivalent noise circuits is implemented as well as an analysis in the frequency domain.
This paper deals with the dc-dc boost converter operating at constant frequency, modulated by the peak-current mode control technique, for duty-cycle larger than 50%. Theoretical analysis is presented along with detailed design procedure and example. A dc-dc boost converter with a universal input voltage range (90-250 V), rated at 400 W, operating at 67 kHz, with a dc output voltage equal to 340 V is designed, simulated, and implemented in laboratory. The experimental and simulation results confirm the validity of the proposed design methodology. (author) 2 refs., 13 figs.
A multiple-input switched-capacitor DC-DCconverter which can realize long battery runtime is proposed in this letter. Unlike conventional converters for a back-lighting application, the proposed converter drives some LEDs by converting energy from solar cells. Furthermore, the proposed converter can charge a lithium battery when an output load is light. The validity of circuit design is confirmed by theoretical analyses, simulations, and experiments.
Several standard tests to evaluate key (direct current) DC/DCconverter parameters were performed on different models of hybrid radiation-hard DC/DCconverters. These tests were done to assess both performance and reliability during space applications that operate the converters at temperatures below the lower military range of -55 C. One of the converters failed near -110 C, but another DC/DCconverter model started normally at temperatures as low as 140 C. The latter showed acceptable performance during turn-on, load transient, and synchronization tests even though some minor anomalies were observed. These results show good promise for its use in applications where the DC/DCconverters will be operated at lower temperatures. An application circuit was also built and preliminary tests were performed on a commercial (low drop out) LDO type of DC to DC converter with adjustable output voltage. These can be used in point of load (POL) applications. This latter device functioned properly on the few tests that were performed; however, more testing is needed to identify potential issues with space use of this and similar devices.
The purpose of this thesis was to investigate the applicability and effects of digital control to line connected switched mode power supplies with power factor correction. The main approach was cost effectiveness with high efficiency. This involved hardware design for increased switching frequency to reduce the size of the magnetic components. A description of different grid regulations was given followed by a set of converter topologies and controllers. Different control techniques were pointed out. Among the listed topologies and control solutions few were selected for further analysis, design and implementation. Many of different hardware and control solutions available on the market were investigated. Most of the commercial power supplies are controlled by dedicated analog controllers in form an integrated circuit. Thus a survey was conducted to analyze the available state-of-art analog controllers and their implemented control algorithms. As digital control has to be competitive with the existing solutions it was investigated what digital signal processing solutions exist. A performance and cost comparison was also presented. The chosen converter topologies were thoroughly analyzed. Different converters were chosen for different power levels. At low power simple boost converter as power factor corrector (PFC) and a RCD-clamped forward converter was chosen as DC-DCconverter. This with has double output and coupled lter inductor. To design a digital controller with the tools of the classical control theory a small signal linearized model of the converter is needed. Detailed modeling and linearizing of the boost converter is presented. At high power level interleaving technique is frequently used to reduce the current stress on the switching components. Though the number of magnetic components is increased they became smaller in size resulting in smaller current ripple through them. An interleaved boost converter with two legs is selected as PFC converter. It was shown that the small signal model of theinterleaved converter is similar to the simple boost converter. Only the simple inductor has to be replaced by the paralleled inductors of each leg. This statement is valid only if the total inductor current is controlled rather than controlling the current in each leg. As second stage a phase-shifted full-bridge converter with synchronous rectication and current doubler was selected. It was shown that for output current and voltage control this topology can be modeled as a interleaved synchronous buckconverter. As it can be seen interleaving technique is also present in this topology. For this topology a fuzzy logic voltage controller is proposed and compared to the traditional PI controller. After modeling the converters controllers can be designed. The controller design was interconnected with the hardware design and control platform. Thus two dfferent prototypes were designed and built with two dierent digital controllers and the controller design, analysis and implementation was based on these two case studies. The first prototype was a 70 W two-stage PFC and DC-DCconverter with boost and forward converters. Average current mode control was selected, designed, simulated an implemented for the boost PFC converter. The two-loop control structure (fast internal current loop and lower bandwidth external voltage loop) was designed for nominal power but system behavior was also analyzed for low-load conditions. The controller was simulated in Matlab/Simulink using PLECS library and embedded Matlab function. All the parameters were treated and scaled just as they appear in the ADC interrupt of the 16 bit fixed point dsPIC30F1010 microcontroller. Peak current control was implemented for the forward converter, using analog comparator module of the digital-signal controller. The waveforms, eciency and power factor results were compared to the performance of an identical two stage 70 W power supply controlled with an analog PFC/PWM integrated circuit. The second prototype was a 600 W two-stage PFC and DC-DCconverter with interleaved boost and phase-shifted full-bridge (PSFB) converters. Average current mode control was designed simulated and implemented for both converters. The sum of the boost inductor current was controlled to shape the line current and the sum of the lter inductor currents in the PSFB converter was controlled to limit over-currents. Low bandwidth PI controllers control the boost DC and the output DC voltages. A fuzzy logic output voltage controller was also simulated and compared to the performance of the PI controller. All four control loops were implemented in a 16 bitfixed point dsPIC33FJ32GS406 microcontroller driving at the same time 8 PWM channels. Finally a brief analysis was done on the eect of the grid disturbances, especially voltage sags on the digital controller. Dierent grid codes and compatibility requirements and system behavior through a boost converter with digital control was presented. In this thesis a deep knowledge of design and digital control of line connected switched mode power supplies with power factor correction was gathered and appropriate solutions were presented. The advancement of this thesis will enable improved design and digital control of high frequency switched mode power supplies in the future. It is concluded that the digital signal processors available today are competitive in performance with the state-of-art analog ICs. The economic reasons for using digital control is not so clear but with falling prices of microcontrollers and increasing demands on the performance of power converters introducing digital control seems to be a reasonable option for the future development of power converters. Advanced control structures can be implemented to improve the performance of switched-mode power-supplies and power factor corrector circuits.
Abstract in spanish En la última década se ha reportado la estrategia de control Zero Average Dynamics (ZAD) como una alternativa al control de los convertidores de potencia, garantizando frecuencia fija de conmutación y bajo error. Sin embargo la estabilidad del sistema depende fuertemente de la carga, por lo cual no es robusto. Cuando se pierde la estabilidad la frecuencia fija de conmutación se pierde también. En este artículo se presenta la generalización de la técnica ZAD dentro (more) del marco de la teoría de probabilidades. Usando este marco es posible recuperar el ZAD tal como ha sido analizado hasta ahora y se pueden generar nuevas estrategias de control, las cuales son más estables que las usadas en el ZAD. Por este motivo a esta técnica se le ha llamado Generalized Zero Average Dynamics (GZAD). Presentamos algunas simulaciones del GZAD aplicado a un convertidor de potencia reductor. Esta nueva estrategia no puede ser obtenida con el ZAD clásico. Las simulaciones numéricas muestran buen desempeño del controlador con bajo error de regulación y robustez ante cambio en la carga. Abstract in english The Zero Average Dynamics (ZAD) strategy has been reported in the last decade as an alternative for controlling power converters. This technique has the advantage of guaranteeing fixed frequency switching. However, the stability of the controller is highly dependent on the load value, and when the stability is lost, the fixed frequency switching is lost too. In this paper we generalize ZAD strategy using the probabilities framework through the expectation operator. Thus, (more) we recover classical sliding mode control classical ZAD strategy, and new control methods can be defined, which are more stable than the others previously used. For this reason, this technique is entitled Generalized Zero Average Dynamics (GZAD). We will show several simulations regarding an application to a DC-DCBuckconverter within the generalized ZAD strategy, which cannot be deduced from the classical ZAD. Numerical simulations show good regulation features and a wide range of stability.
An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.
Maximizing electrical energy generation through waste heat recovery is one of the modern research questions within automotive applications of thermoelectric (TE) technologies. This paper proposes a novel concept of distributed multisection multilevel DC?DC conversion networks based on thermoelectric generators (TEGs) for automotive applications. The concept incorporates a bottom-up design approach to collect, convert, and manage vehicle waste heat efficiently. Several state-of-the-art thermoelectric materials are analyzed for the purpose of power generation at each waste heat harvesting location on a vehicle. Optimal materials and TE couple configurations are suggested. Moreover, a comparison of prevailing DC?DC conversion techniques was made with respect to applications at each conversion...
The cost challenges being faced by promoters of new traffic compatible vehicles were looked at with regard to regenerative controllers, dc/dcconverters, chargers, single-point watering and the bigger batteries and motors required to speed up electric vehicles. A preview of what the electric vehicle industry of the United Kingdom will be offering in the next 5 years is given.
A novel technique for efficiently extracting maximum power from photovoltaic (PV) panels is presented. The power conversion stage, which is connected between a PV panel and a load or bus, is a SEPIC or Cuk dc/dcconverter operating in discontinuous inductor-current or capacitor-voltage mode. The met...
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a DC-DCconverter and their degradation was monitored over an extended period of ... ements of a switched mode power supply that fails more fre- quently and has a ... The output ripple voltage and leakage current are pre- sented as a function .... The residuals have a mean very close to zero and a variance of 2.1829. This ...
Several DC-DCconverters based on voltage multipliers have been recently published with advantages such as high voltage gain and few inductors used. This paper presents a generalized topology from which several of the state of the art and new topologies may be derived.
In a review paper [1] (El Aroudi, et al., 2005), two stability conditions for DC-DCconverters are presented. However, these two conditions were published years earlier at least in a journal paper [2] (Fang and Abed, 2001). In this note, the similar texts of [1] and [2] are compared.
Battery/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC/DCconverter, to regulate output voltage from different inputs. The proposed multi-input conver...
A novel technique for efficiently extracting the maximum output power from a solar panel under varying meteorological conditions is presented. The methodology is based on connecting a pulse-width-modulated (PWM) dc/dc SEPIC or Cuk converter between a solar panel and a load or battery bus. The conver...
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This paper presents the design of digital controls of PWM DC-DCconverters on a digital signal processor (DSP) based platform. Three digital control approaches are being investigated: discretisation of analog control, digital proportional-integral-derivative (PID) control, and deadbeat control. Simu...
A basic experiment was carried out on a supplementary power supply, in which solar cells and electric double layer capacitors(EDLC) were combined for a DC/DCconverter, for the use of a solar-electric vehicle (S-EV); and in actuality, an S-EV was loaded with the power supply with a running test conducted on a public road. The EDLC was found effective and useful for avoiding temporary lowering of voltage and momentary break. An electric supply was thereby made possible for an emergency light without the use of the DC/DCconverter. However, in a tunnel or a night driving and in case of failure of the DC/DCconverter, an operating time of only 7 minutes or so was affordable with the EDLC having a capacity of 100F. Moreover, particularly with a heavy load, it was impossible to maintain a voltage for many hours. Under the circumstances, an S-EV design would primarily require two sets of independent DC/DCconverter loaded in the future. The EDLC, young after it was developed, still has a small energy density compared with a lead storage battery. Yet, an EDLC with a higher performance being developed, there is a possibility that it will be applied to S-EV`s by utilizing its characteristics such as a high efficiency and a long service life. 4 refs., 8 figs.
A switching frequency of 5 MHz allows the integration in a chip of a low power (10W) DC/DCconverter. Although this switching frequency would make feasible a voltage mode control with 1MHz bandwidth, the parasitics and robustness don't allow such a high frequency bandwidth. This paper proposes a fas...
The recent magnetics research and development including micromachine, magnetic meterial and biomagnetics fields has come to the new deveropment stage. The representative studies are outlined from these fields. First, Micro dc motor is mentioned as an example of the machine application. Next, miniaturized DC-DCconverter using the magnetic thin film inductor are explained. Finally, the magnetic field effect to the organism is introduced.
In this paper a comparison among three control strategies is presented, with application to a boost DC-DCconverter. The control strategies are developed on the switched boost circuit model and validated on the nonlinear model by use of simulations. The classical PID, a 2dof-IMC (two degree of freed...
By adding a suitable LC filter to the input of a Buckconverter, it is possible to force the converter into discontinuous-input-voltage mode operation. A Buckconverter in this mode of operation has useful properties such as power factor correction and soft turn-off switching. The operation, modelin...
Fuel cell is one of the promising renewable and sustainable power sources because of its high power density and very low emission. It can be utilized as a clean power source for various applications such as portable electronic appliances, transportation and residential building. In order to design a highly efficient fuel cell power system, a suitable DC-DCconverter is required. Among the various topologies of DC-DCconverters, interleaved boost converter (IBC) has been proposed as a suitable interface for fuel cells to convert low voltage high current input into a high voltage low current output. The advantages of interleaved boost converter compared to the classical boost converter are low input current ripple, high efficiency, faster transient response, reduced electromagnetic emission ...
At the end of October 2009, KELK Ltd. started a field test of the thermoelectric generation system at a carburizing furnace of Komatsu Ltd., Awazu Plant. Residual carburizing gas based on CO, H2 and N2 is burned resulting that 20-30 kW range of flame constantly heats up the hot side of TEG. A single unit of TEG consists of 16 of the Bi-Te thermo-modules, each of which has a size of 50 × 50 × 4.2 mm3 and can generate 24W under the circumstance of 280 °C and 30 °C of hot side and cold side temperature, respectively [1]. 16 modules are separated into 4 groups and they are connected electrically depending on design concept, namely in case of focusing on reliability, parallel connection are used and in case of on simplicity and high-voltage transmission, series connection is preferably employed. The module is being life-time tested at various conditions. For instance, 10,000 of heat cycling under the hot side temperature between 250 and 50 °C with a constant cold side temperature at 30 °C gives within a few percent degrade. Both buck-and booster-type DC/DCconverters controlled by one chip computer were set up and Maximum Power Point Tracking (MPPT) was well facilitated to search for the maximum output power depending on the hot and cold temperature. The electric output power from the 16 modules is summed up to charge 4 lead storage batteries (12V-65Ah) and then through DC/AC inverters electricity goes to LED light tubes inside the factory. 214 W can be generated and 180 W is delivered to the batteries.
A comparison of an analog and a digital controller driven 70 W two-stage power factor corrector converter is presented. Both controllers are operated in average current-mode-control for the PFC and peak current control for the DC-DCconverter. Digital controller design and converter modeling is described. Results show that digital control can compete with the analog one in efficiency, PFC and THD.
A power converter architecture interleaves full bridge converters to alleviate thermal management problems in high current applications, and may, for example, double the output power capability while reducing parts count and costs. For example, one phase of a three phase inverter is shared between two transformers, which provide power to a rectifier such as a current doubler rectifier to provide two full bridge DC/DCconverters with three rather than four high voltage inverter legs.
We present data on the vulnerability of a variety of candidate spacecraft electronics to proton and heavy-ion induced single-event effects and proton-induced damage. We also present data on the susceptibility of parts to functional degradation resulting from total ionizing dose at low dose rates (0.003-0.33 Rads(Si)/s). Devices tested include optoelectronics, digital, analog, linear bipolar, hybrid devices, Analog to Digital Converters (ADCs), Digital to Analog Converters (DACs), and DC-DCconverters, among others.
A novel dc-dcconverter is presented, whose significant advantages are the single power switch, isolation, inherent overcurrent protection and operation at constant frequency in a conventional pulse width modulation. The new converter is suitable to operate over a very wide input voltage range and can be employed in power factor correction and multiple output power supply. Theoretical analysis and experimental results were taken from the converter rated at 300 W/50 kHz. (author) 4 refs., 10 figs.
This project was to produce innovative DC-DC power converter concepts which are appropriate for the power exchange between the Orbiter and the Space Station Freedom (SSF). The new converters must interface three regulated power buses on SSF, which are at different voltages, with three fuel cell power buses on the Orbiter which can be at different voltages and should be tracked independently. Power exchange is to be bi-directional between the SSF and the Orbiter. The new converters must satisfy the above operational requirements with better weight, volume, efficiency, and reliability than is available from the present conventional technology. Two families of zero current DC-DCconverters were developed and successfully adapted to this application. Most of the converters developed are new and are presented.
A series/parallel resonant dc-dcconverter with secondary-side resonance and a novel input ``boosting`` feature is described. In order to greatly reduced the conduction loss (factor of 4) due to circulating currents in the resonant components, the boost circuit, which requires no additional active switches, operates only when needed during transient input voltage dips. This reduces the effective input voltage range over which the converter must operate and allows optimization at the steady-state input voltage. The converter employs highly efficient resonant inductors and novel z-folded thin flex circuit transformer windings in order to meet a density of greater than 50 W/in{sup 3} with an efficiency approaching 95%. The dc-dcconverter was developed for use as a 270 to 50 V line converter for distributed power applications.
The trend toward high power density, high operating frequency, and low profile in power converters has exposed a number of limitations in the use of conventional wirewound magnetic component structures. Transformers made of the planar principle eliminate virtually some shortcomings of old?fashioned wire wound types, and thus planar magnetics, has in recent years, become increasingly popular in high frequency power converters. First, an overview of basic planar magnetics technology used in general dc?dcconverters is presented. PCB or flexible PCB windings as a main construction together with planar cores yield a number of advantages over the conventional magnetics. Meanwhile, some limitations of planar magnetics are also introduced. Secondly, fundamental characteristics of planar magnetics are investigated through winding conduction loss, core loss, leakage inductance and interwinding capacitance. Accordingly, a clear cognition for the intrinsic properties of planar magnetics has been given. Trade?offs is unavoidable in the magnetics design, and thus an analysis of tradeoffs is necessary for an optimum design in a high quality dc?dcconverter. In addition, an improved interwinding arrangement is proposed to further reduce winding conduction loss, leakage inductance, and even interwinding capacitance. With the development of multilayer PCB, the integrated magnetics with planar structure can be easily implemented. Hence, planar integrated magnetics technique as a major part of this thesis is investigated. The history and the evolution of integrated magnetics in power converters have been described. It is recalled, that integrated magnetics allows less number of parts, lower volume and cost of the converter, and higher efficiency. Many innovative ideas are proposed and experimentally verified. • E?I?E core structure with integrated transformers and inductors is applied into the two recent developed dc?dc topologies. • A new method to integrate the current balancing transformer with common input inductor for the primary?parallel dc?dcconverter is proposed. • A low profile and low cost integrated inductors with stacked I?cores for multiplephase interleaved dc?dcconverters is proposed. • Ultra?thin coupled inductors design for flexible PV module is introduced. A 1.5? mm thickness integrated coupled inductor with sandwich core structure is under investigation. • A “four quadrants integrated transformer” utilizing orthogonal flux to decouple the two primary windings has been applied to a dual?input isolated boost dc?dcconverter.
An integrated zero-voltage-switching (ZVS) DC-DCconverter with continuous input current and high voltage gain is proposed. The proposed converter can operate with soft switching, a continuous inductor current and fixed switching frequency. The voltage stress of the power switches is relatively low compared to the output voltage. Moreover, soft-switching characteristic of the proposed converter reduces switching loss of active power switches and raise the conversion efficiency. The reverse-recovery problem of output rectifiers is also alleviated by controlling the current changing rates of diodes with the use of the leakage inductance of a coupled inductor. The operation and performance of the proposed DC-DCconverter were verified on an 115 W experimental prototype operating at 100 kHz.
This article deals with pulse width modulation (PWM) and pulse position modulation (PPM) DC to DC converters. A tri-phase PWM converter is made of 6 simple DC/DCconverters grouped together into 3 reversible converters of the same type: 1 - single-quadrant voltage lowering converters (hydraulic analogy, study with ideal elements, full scheme with input and output filters); 2 - single-quadrant voltage raising converters (hydraulic analogy, operation); 3 - two quadrants reversible converters (structure construction, quadrants of operation, reversible converter connected to a DC motor); 4 - four-quadrants reversible converters; 5 - other converters structure (current converters and converters with intermediate storage, asymmetrical converters, converters with capacitive storage, insulated converters, resonating converters, status); 6 - conclusion. (J.S.)
Based on the association of super-capacitors with an electrochemical battery, this energy storage system developed by the Federal Polytechnic School of Lausanne (Switzerland) offers the advantages of both components: an important quantity of energy stored, and an instantaneous power much greater than the one suppliable by a normal battery. This super-battery requires the use of static converters (reversible DC-DCconverters) and of a voltage regulator to manage both energy sources. (J.S.)
Power MOSFETs used as synchronous rectifiers in isolated DC to DC converters allow to design energy efficient power supplies. In order to improve the efficiency of the isolated DC-DCconverter of about 5%, the synchronous controller rectifier designed by International Rectifier is based on a predictive method in order to generate the appropriate signals for the driving of the secondary stage MOSFETs. In addition, the PWM architecture of the primary stage is not modified. (J.S.)
This paper deals with the implementation of an output current estimator for a DC-DC Multiplier Boost Converter (MBC). For that purpose, a real time platform is used for solving the dynamic equations of a nonlinear adaptive observer. Excellent performance is achieved even during demanding conditions. In particular, a reliable estimation is obtained when an experimental nonlinear dynamic system is utilized as an electric load connected at the converter terminals.
Asymmetric control scheme is an approach to achieve Zero Voltage Switching (ZVS) for half bridge isolated DC-DCconverters. Due to the switching property included in their structure, DC-DCconverters have a nonlinear behavior and their controller design is accompanied with complexities. But by employing the average method it is possible to approximate the system into a linear system and then linear control methods can be used. Dynamic performance of half bridge converters output voltage can be controlled by Pole placement and PID controllers. In this paper, Genetic Algorithm is used to optimize the system to achieve the optimum dynamic response. Matrix coefficients and dominant poles of closed loop transfer function is selected based on Genetic Algorithm. The results show an improvement in...
Purpose - The purpose of this paper is to suggest a new analytical methodology for transient analysis of DC-DC power converters. The closed-form solution obtained following this methodology is suitable both for design of passive elements of the converter and for the development of control techniques. Design/methodology/approach - The methodology is based on a mixed use of Laplace transform and z-transform. The expressions of variables of the set of equations, characteristic of a DC-DCconverter, are first evaluated in the Laplace domain for the generic switching interval. The solutions obtained are then z-transformed in order that they match in each contiguous time interval, to form the complete transient response. Findings - The new solution methodology allows the analytical determination...
In this paper the development of a new laboratory prototype for the emulation of a photovoltaic (PV) field is presented. The proposed system is based on a DC/DC step-down converter topology and allows to obtain the solar array I-V curves, taking into account the environmental changes in solar irradiance and cell temperature. The DC/DCconverter control strategy is deduced by using a comprehensive mathematical model of the PV field whose parameters are obtained from the knowledge of: (a) maximum power point data, measured when the PV plant power converter is running, (b) open circuit voltage and short-circuit current, measured off-line. This approach allows the most accurate representation of the PV source. Computer simulations and experimental results demonstrate that the proposed circuit ...
This letter presents the design of a window successive approximation (SAR) analog-to-digital converter (ADC) using an ultra-fast, offset-cancelled auto-zero comparator for digital DC???DCconverters. It is designed in a standard CMOS 0.18 ?m process. The ADC has a dynamic reference voltage range to reduce power consumption. The auto-zero scheme of the comparator is realized internally with a preamplifier stage and a latch stage. Post-layout simulation shows that the response time of the comparator from low-to-high and high-to-low is 3.78 ns and 2.47 ns, respectively. The resolution of the proposed window SAR ADC is 7.5 mV. The ADC is fabricated as part of a digital DC???DCconverter integrated circuit and measurement results show that an average power consumption of 0.8 ?W is achiev...
A new design approach achieving very high conversion efficiency in low-voltage high-power isolated boost dc-dcconverters is presented. The transformer eddy-current and proximity effects are analyzed, demonstrating that an extensive interleaving of primary and secondary windings is needed to avoid high winding losses. The analysis of transformer leakage inductance reveals that extremely low leakage inductance can be achieved, allowing stored energy to be dissipated. Power MOSFETs fully rated for repetitive avalanches allow primary-side voltage clamp circuits to be eliminated. The oversizing of the primary-switch voltage rating can thus be avoided, significantly reducing switch-conduction losses. Finally, silicon carbide rectifying diodes allow fast diode turn-off, further reducing losses. Detailed test results from a 1.5-kW full-bridge boost dc-dcconverter verify the theoretical analysis and demonstrate very high conversion efficiency. The efficiency at minimum input voltage and maximum power is 96.8%. The maximum efficiency of the proposed converter is 98%.
A voltage-mode DC-DCconverter with a novel oscillator and ramp generator is presented. The proposed oscillator and ramp generator has a simple structure and does not need an external reference signal generator to set the upper and lower levels of the ramp signal. The DC-DCconverter was fabricated in a standard 0.5µ m CMOS process. The converter can operate from 465kHz to 556kHz with a supply voltage from 3 to 5.5V, which is appropriate for portable electronic devices that are powered by a single-cell lithium-ion battery. The output ripple voltage is about 10mV with a 10µ F off-chip capacitor and a 10µ H off-chip inductor. The power conversion efficiency is over 80% for load currents from 30 to 400mA.
In this paper, a ring-type SC DC-DCconverter with novel bootstrapped gate transfer switches is proposed. The bootstrapped gate transfer switches are used to achieve higher efficiency. In the proposed bootstrap circuit, maximum voltage of the power converter is charged to a capacitor via maximum circuits constructed with diodes. By connecting the charged-capacitor between the gate terminals of power-switches and the output terminal of the maximum circuit, the bootstrap circuit avoids the threshold voltage drop of power-switches. Concerning the DC-DCconverter designed by a 1.2 ?m CMOS technology, SPICE simulations are performed to investigate the characteristics of the circuit. The SPICE simulations show that the efficiency of the DC-DCconverter with proposed bootstrap circuits is more than 90 % when the output load Ro satisfies Ro > 200 ?. When Ro = 100 ?, the proposed circuit can improve efficiency up to 8.7 % of a conventional converter. The validity of the circuit design for the bootstrap circuit is also confirmed by experiments.
Energy harvesting systems stimulate the development of power management for low power consumption applications. Improving the converter efficiency of power management circuits has become a significant issue in energy harvesting system design. This paper presents a variable step-down conversion ratio switched capacitor (SC) DC-DCconverter to advance the converter efficiency of charge on the stored capacitor in a wireless monitoring system of orthopedic implants. The converter is designed to work at 1 MHz switching frequency and achieves 15 to 2 V conversion. Measurement results show that the converter efficiency can reach 42% including all circuit power consumption, which is much higher than previous work. (semiconductor integrated circuits)
In this paper the development of a new laboratory prototype for the emulation of a photovoltaic (PV) field is presented. The proposed system is based on a DC/DC step-down converter topology and allows to obtain the solar array I-V curves, taking into account the environmental changes in solar irradiance and cell temperature. The DC/DCconverter control strategy is deduced by using a comprehensive mathematical model of the PV field whose parameters are obtained from the knowledge of: (a) maximum power point data, measured when the PV plant power converter is running, (b) open circuit voltage and short-circuit current, measured off-line. This approach allows the most accurate representation of the PV source. Computer simulations and experimental results demonstrate that the proposed circuit acts as a highly accurate and efficient laboratory simulator of the photovoltaic array electrical characteristics both in steady state and transient conditions. Partial shading and fluctuating conditions can be reproduced too. Moreover the dynamic behaviour of the proposed laboratory emulator is suitable to its effective connection to power electronic interface to the utility or to load through a DC/DC boost converter. (author)
This work deals with the performances and responses of a grid-connected photovoltaic (PV) plant in normal and disturbed modes. The system is composed of a solar array, a dc-dcconverter and a three-phase inverter connected to the utility grid. On the one hand a suitable control of the dc-dcconverter is developed in order to extract the maximum amount of power from the PV generator. On the other hand an active and reactive power control approach (PQ) has been presented for the inverter. This method can provide a current with sinusoidal waveform and ensure a high power factor. Therefore, the grid interface inverter transfers the energy drawn from the PV into the grid by ensuring constant dc link voltage. Modeling and controlling were carried out using the informational graph of causality an...
In this work, we investigate the use of the Dynamical System Theory to increase the efficiency of the satellite power supply subsystems. The core of a satellite power subsystem relies on its DC/DCconverter. This is a very nonlinear system that presents a multitude of phenomena ranging from bifurcations, quasi-periodicity, chaos, coexistence of attractors, among others. The traditional power subsystem design techniques try to avoid these nonlinear phenomena so that it is possible to use linear system theory in small regions about the equilibrium points. Here, we show that more efficiency can be drawn from a power supply subsystem if the DC/DCconverter operates in regions of high nonlinearity. In special, if it operates in a chaotic regime, is has an intrinsic sensitivity that can be exploited to efficiently drive the power subsystem over high ranges of power requests by using control of chaos techniques.
In this work, we investigate the use of the Dynamical System Theory to increase the efficiency of the satellite power supply subsystems. The core of a satellite power subsystem relies on its DC/DCconverter. This is a very nonlinear system that presents a multitude of phenomena ranging from bifurcations, quasi-periodicity, chaos, coexistence of attractors, among others. The traditional power subsystem design techniques try to avoid these nonlinear phenomena so that it is possible to use linear system theory in small regions about the equilibrium points. Here, we show that more efficiency can be drawn from a power supply subsystem if the DC/DCconverter operates in regions of high nonlinearity. In special, if it operates in a chaotic regime, is has an intrinsic sensitivity that can be explo...
A new (12+1)-channel block-addressing driving method and a cost-effective drive IC have been successfully developed. The power consumption of the new block-addressing driving method is nearly 50% less than that of the conventional block-addressing method. The panel integrated dc/dcconverter for the voltage of transistor-turning-off (Voff) enabled us to reduce the size and the manufacturing cost of the driver IC. On the basis of these technologies, a 1.89? active-matrix liquid crystal display with 240 × RGB × 320 pixels was fabricated with a data driver, a dc/dcconverter for Voff, a gate driver, and a level shifter for a gate driver. The power consumption of the panel using the low-voltage driving liquid crystal is typically 13 mW.
In this paper, a new control method for maximum power point tracking (MPPT) in stand-alone-type PV generaton systems is proposed. In this control method, the operations detecting the maximum power point and tracking its point are alternately carried out by using a step-up DC—DCconverter. This method requires neither the measurement of temperature and insolation level nor PV array model. In a stand-alone-type application with a battery load, the design method for the boost inductance L of the step-up DC—DCconverter is described, and the experimental results show that the use of the proposed MPPT control increases the PV generated energy by 14.8% compared to the conventional system.
A digital Nonlinear Proportional-Integral-Derivative (NPID) control algorithm was proposed to control a 1-kW, PWM, DC/DC, switching power converter. The NPID methodology is introduced and a practical hardware control solution is obtained. The design of the controller was completed using Matlab (trademark) Simulink, while the hardware-in-the-loop testing was performed using both the dSPACE (trademark) rapid prototyping system, and a stand-alone Texas Instruments (trademark) Digital Signal Processor (DSP)-based system. The final Nonlinear digital control algorithm was implemented and tested using the ED408043-1 Westinghouse DC-DC switching power converter. The NPID test results are discussed and compared to the results of a standard Proportional-Integral (PI) controller.
NTT has developed a portable fuel cell system (PFCS) for telecommunications systems. The PFCS consists of a small fuel cell, a hydrogen cylinder, a 55 V DC-DCconverter and a carrier. The PFCS supplies 250 W of DC power for 5 hours using the 10.5 l hydrogen cylinder. The system can be moved easily by using the carrier. The DC-DCconverter can allocate the current equally to each PFCS, and the parallel connections between the PFCSs increase the power that can be generated for telecommunications equipment. Simultaneous operation of three PFCSs provides enough power to operate a telecommunications system in a building. The operation remains stable whether commercial power is discontinued intentionally or unintentionally. The PFCS generates power quietly and cleanly, find proved to be used as an indoor emergency power source for telecommunications systems. 12 refs., 8 figs., 2 tabs.
A novel scheme for the speed control of a permanent magnet (PM) dc motor drive incorporating artificial neural network (ANN) is proposed. The drive system includes an ANN speed controller, micro-processor based dc-dcconverter and a laboratory PM dc motor. A multi-layer artificial neural network structure with a feedback loop is designed in order to precisely operate the control circuit for the dc-dcconverter. The complete drive system is simulated and implemented in real time. Both the simulation and experimental results prove the inherent capability of the ANN which makes it possible to maintain desired speed control in the presence of parameter variations and load disturbances. The performances of the ANN based PM dc drive system are compared with the simulated results of the conventionally controlled drive system. This clearly indicates the better performance of the ANN based PM dc motor drive system, particularly in case of parameter and load variations.
Abstract-In this paper, an extended run time DC UPS system structure with fuel cell and supercapacitor is investigated. A wide input range bi-directional dc-dcconverter is described along with the phase-shift modulation scheme and phase-shift with duty cycle control, in different modes. The delivered power and peak current are analyzed and calculated. The key parameters of the bi-directional dc-dcconverter, the relationships between the input voltage, phase-shift angle, ratio of the transformer and leakage inductance are analyzed and optimized. Build the system mathematic model and a novel input voltage combined with load current feedback using PI controller with anti-windup scheme to realize closed-loop control of the whole system, and verify the feasibility of the control scheme proposed by simulation. A 1kW prototype controlled by TMS320F2808 DSP is implemented and tested. Experimental results show the validity of design.
A digital Nonlinear Proportional-Integral-Derivative (NPID) control algorithm was proposed to control a 1-kW, PWM, DC/DC, switching power converter. The NPID methodology is introduced and a practical hardware control solution is obtained. The design of the controller was completed using Matlab (trademark) Simulink, while the hardware-in-the-loop testing was performed using both the dSPACE (trademark) rapid prototyping system, and a stand-alone Texas Instruments (trademark) Digital Signal Processor (DSP)-based system. The final Nonlinear digital control algorithm was implemented and tested using the ED408043-1 Westinghouse DC-DC switching power converter. The NPID test results are discussed and compared to the results of a standard Proportional-Integral (PI) controller.
This paper presents the performance analysis method for the DC-DCconverter with the MHz band transformer. In this method 3D electromagnetic field analysis employing finite element method (FEM), in which the displacement current is taken into consideration, is coupled with the circuit analysis. The performances of the transformer, such as input/output power and efficiency, are computed, and the validity of this method is confirmed through comparison of the computed and measured results. Furthermore the performances of a DC-DCconverter with the transformer are calculated using the equivalent circuit of the transformer obtained from the results of FEM analysis. As the results, it is found that the calculated and measured input/output performances are in good agreement.
Power generated from a piezoelectric material usually comes with poor characteristics such as high voltage, low current and high impedance. In order to drive the embedded sensor circuit, piezoelectric power needs to be characterized and regulated. In this paper, we present an analysis on the power generation characteristics and the efficiency of power conversion of the stiff lead zirconate titanate (PZT) ceramics. Moreover, a power circuit design is put forward in the application where PZT elements are used for power generation in a TKR implant. A hybrid direct current (DC)?DC, comprising a switched capacitor (SC) DC?DCconverter and a low dropout (LDO) linear voltage regulator, is presented. The variable ratio SC converter has been taped out with 0.35??m CMOS technology. The test results ...
Methods and algorithms used for the simulation of elementary power conditioning units buck, boost, and buck-boost, as well as shunt PWM are described. Definitions are given of similar converters and reduced parameters. The various parts of the simulation to be carried out are dealt with; local stability, corrective network, measurements of input-output impedance and global stability. A simulation example is given.
A charge-average type DC-DCconverter for cellular phones is proposed in this paper. The converter is designed by using switched-capacitor (SC) techniques. In the proposed power converter, the DC-DC conversion is performed by iterating the following processes. Firstly, an input voltage Vin is charged in capacitors which are connected in series. In this timing, an output voltage is taken out from arbitrary terminals of the capacitors. Next, the electric charges are equalized by connecting the capacitors in parallel. Therefore, different from conventional converters such as a series-parallel type converter and a Dickson-type converter, the proposed converter can provide stepped-down and stepped-up voltages which are expressed by (Q/P)×Vin (P ? {1, 2,..., N} and Q ? {1, 2,..., N}). Furthermore, the hardware cost for the proposed converter is smaller than that for the conventional SC power converters such as a ring-type converter and a series-parallel type converter. Concerning 3-stage power converters, SPICE simulations are performed to confirm the validity of the circuit design. For the input voltage 3.6 V, the power efficiency of the proposed circuit is about 90 % in the output current about 300 mA.
This paper describes a novel speed control scheme to operate a current source inverter (CSI) driven surface-mounted permanent magnet synchronous machine (SPMSM) for hybrid electric vehicles (HEVs) applications. The idea is to use the angle of the current vector to regulate the rotor speed while keeping the two dc-dcconverter power switches on all the time to boost system efficiency. The effectiveness of the proposed scheme was verified with a 3 kW CSI-SPMSM drive prototype.
The flexibility of a three-phase ac to dc rectifier topology is presented in this paper. The rectifier can be adapted to suite the desired application, by simply using different dc-dcconverter topologies. The control of the rectifier remains simple in spite of the modifications. This paper presents the robustness of the rectifier to unbalances in the utility voltages and its application to high power and voltage levels. 5 refs, 4 figs
The small-signal transfer functions of DC/DC switch-mode converters are defined in the frequency domain via a two-port model of the whole closed-loop system (i.e., power cell, error-amplifier, PWM modulator) and via a three-port model of the open-loop power cell plus PWM modulator. Applications of these functions in power-system design are shown. Measurement techniques are discussed in detail and relevant results are reported.
The liquid-nitrogen temperature (77 K) operation of a 55 W, 200 kHz, 48/28 V zero-voltage switching multi-resonant dc/dcconverter designed with commercially available components is reported. Upon dipping the complete converter (power and control circuits) into liquid-nitrogen, the converter performance improved as compared to the room-temperature operation. The switching frequency, resonant frequency, and the characteristic impedance did not change significantly. Accordingly, the zero-voltage switching was maintained from no-load to full-load for the specified line variations. Cryoelectronics can provide high density power converters, especially for high power applications.
A DC-DCconverter is designed according to the request of the electric propulsion system for a fuel cell sightseeing car. The converter adopts a simple topography - full bridge circuit. The main switch transistors are driven by the module TL494, based on pulse-width modulation method. A high accuracy linear optical coupler is used to isolate analogy signal in order to guarantee the stabilization of the converter. Experiments show that the converter can satisfy the requirements of the power match between the fuel cell and the motor under the ordinary operation conditions.
Large power conditioning mass reductions will be required to enable megawatt power systems envisioned by the Strategic Defense Initiative, the Air Force, and NASA. Phase 1 of a proposed two phase interagency program has been completed to develop an 0.1 kg/kW DC/DCconverter technology base for these future space applications. Three contractors, Hughes, General Electric (GE), and Maxwell were Phase 1 contractors in a competitive program to develop a megawatt lightweight DC/DCconverter. Researchers at NASA Lewis Research Center and the University of Wisconsin also investigated technology in topology and control. All three contractors, as well as the University of Wisconsin, concluded at the end of the Phase 1 study, which included some critical laboratory work, that 0.1-kg/kW megawatt DC/DCconverters can be built. This is an order of magnitude lower specific weight than is presently available. A brief description of each of the concepts used to meet the ambitious goals of this program are presented.
To improve the power sequencing performance of the system-on-a-chip (SOC), a novel embedded soft-start circuit is presented. A seamless soft-start reference voltage is obtained with 7 bits DAC, which can not only restrain the turning point overshoot, but also improve the output accuracy and the poor loading capability, reduce the pin number and save PCB area. The whole DC-DCconverter has been fabricated in a 0.35 {mu}m CMOS process. The measurement results show that the chip starts up successfully with 250 {mu}s soft-start time under conditions of 400 kHz switching frequency, 2.5 V DC-DC output and 1.8 V LDO output. Stable operation after soft-start is also shown. (semiconductor integrated circuits)
Maximizing electrical energy generation through waste heat recovery is one of the modern research questions within automotive applications of thermoelectric (TE) technologies. This paper proposes a novel concept of distributed multisection multilevel DC-DC conversion networks based on thermoelectric generators (TEGs) for automotive applications. The concept incorporates a bottom-up design approach to collect, convert, and manage vehicle waste heat efficiently. Several state-of-the-art thermoelectric materials are analyzed for the purpose of power generation at each waste heat harvesting location on a vehicle. Optimal materials and TE couple configurations are suggested. Moreover, a comparison of prevailing DC-DC conversion techniques was made with respect to applications at each conversion level within the network. Furthermore, higher-level design considerations are discussed according to system specifications. Finally, a case study is performed to compare the performance of the proposed network and a traditional single-stage system. The results show that the proposed network enhances the system conversion efficiency by up to 400%.
The electricity produced by a thermoelectric generator (TEG) must satisfy the requirements of specific loads given the signal level, stability, and power performance. In the design of such systems, one major challenge involves the interactions between the thermoelectric power source and the power stage and signal-conditioning circuits of the load, including DC?DC conversion, the maximum power point tracking (MPPT) controller, and other power management controllers. In this paper, a survey of existing power electronics designs for TEG systems is presented first. Second, a flat, wall-like TEG system consisting of 32 modules is experimentally optimized, and the improved power parameters are tested. Power-conditioning circuitry based on an interleaved boost DC?DCconverter is then developed fo...
This book deals with the analysis of power electronic converters and of their conducted disturbances, in particular the emission of harmonic currents. The basic electrical and electrotechnical knowledge is recalled first (power distribution systems, transformers..) and then the different types of converters are presented in a first chapter and illustrated with a description and a numerical analysis of each of them: DC-DC, AC-AC, AC-DC and DC-AC converters. A second chapter is devoted to low voltage single-phase and tri-phase distribution systems and transformers. (J.S.)
The boost converter with the three-state switching cell seems to be a good candidate for a dc-dc stage for non-isolated generators based on alternative energy sources. It provides a high voltage gain, a reduced voltage stress on transistors and limited input current ripples. In this paper the focus is on performance improvement of this type of the converter. Use of foil windings helps to reduce conduction losses in magnetic components and to reduce size of these components. Also it has been demonstrated that the regulation range of this type of converter can be increased by operation with duty cycle lower than 50%.
This paper presents a bidirectional dc/dcconverter operated with batteries both in the input and output. Primary parallel isolated boost converter (PPIBC) with transformer series connection on the high voltage side is preferred due to its ability to handle high currents in the low voltage side. The converter has been modeled using non-ideal components and operated without any additional circuitry for startup using a digital soft-start procedure. Simulated and measured loop gains have been compared for the validity of the model. On-the-fly current direction change has been achieved between input and output battery banks with a defined ramp.
A current-mode buckDC-DC controller based on adaptive on-time (AOT) control is presented. The on-time is obtained by the techniques of input feedforward and output feedback, and the adaptive control is achieved by a sample-hold and time-ahead circuit. The AOT current-mode control scheme not only obtains excellent transient response speed, but also achieves the independence of loop stability on output capacitor ESR. In addition, the AOT current-mode control does not have subharmonic oscillation phenomenon seen in fixed frequency peak current-mode control, so there is no need of the slope compensation circuit. The auto-skip pulse frequency modulation (PFM) mode improves the conversion efficiency of light load effectively. The controller has been fabricated with UMC 0.6-mum BCD process successfully and the detailed experimental results are shown.
The conference presents papers on dc-dc power topologies, inverters and cycloconverters, power semiconductor devices, high-power conversion, dc-to-dc converters, systems and simulation, static power converters, ac drives, analysis and controls. Specific topics include 500 V BIMOS technology and its applications, state plane analysis of a parallel resonant converter, the application of power MOSFET at 10 MHz, the automatic interconnection between solar cells and an inverter, bipolar power flow in a dc/ac converter with only one high-frequency switch pair, high-power asymmetrical thyristors, a series resonant converter using flyback control, and an electronic power conditioner for carcionotrons. Papers are also presented on the fast transient behavior of thyristor switches, a novel sine wave in an ac-to-dc converter with high-frequency transformer isolation, high-Q approximations in the small signal analysis of resonant converters and straightforward discrete modeling for power converter systems.
The goal of this paper is to evaluate an interleaved buck topology for driving high current light-emitting diodes. Low output capacitor value allows the use of non-electrolytic capacitors extending the lifetime of the converter. Converter is operated as a constant, regulated current source which increases luminous efficacy of LED compared to PWM dimmed system. Because of the low dynamic resistance of LEDs the duty cycle of the converter does not change greatly with controlled current. By setting the input voltage of the buckconverter to around twice the voltage of diode strings, converter can be operated close to the 50% duty cycle, where the ripple attenuation is the highest.
Attention is given to several multikilowatt power electronic components developed by TRW for the Space Station Power Management and Distribution test bed at NASA Lewis Research Center. These components include a 12.5-kW DC-DCconverter, a 6.25-kW battery charge/discharge regulator, an 82-channel sequential shunt unit, a 10-A remote power controllers, and three different types of 1-kW load converters. TRW is also monitoring the development of 120-V fuses for space applications. The authors discuss these developments and provide steady-state and dynamic performance parameters.
Box-level total dose testing of the FOG (Fiber Optic Gyro) by IXSEA at ESA's GammabeamFacility were abruptly terminated at 8krad (Si) due to catastrophic failure (complete shutdown). This was unexpected because all components within the gyro were supposedly radiation tolerant. Further testing showed that the components responsible for the failure were two DC-DCconverters, manufactured by Interpoint, that stopped regulating shortly before shutdown. This paper summarizes diagnostic test results for the converters to determine the underlying cause of the unexpected failure at low levels of radiation.
A new method for achieving self-oscillating, self-interleaved operation of class E derived resonant DC/DCconverters is presented. The proposed method is suitable for operation at frequencies in the Very High Frequency (VHF) band. Interleaved and self-oscillating modes of operation are achieved at the same time with very small number of additional passive components in the interconnection network. To verify the proposed technique, a 110MHz prototype resonant boost converter was designed; experimental results and comparison with SPICE simulation are presented. Peak measured efficiency was 89% in continuous operation.
Output voltage regulation problem of DC-DC boost power converters is studied based on an averaged model with a practical inductor. This paper exploits the effect of inductor's parasitic resistance on the performance of an existing parallel-damped (PD) passivity-based controller (PBC) under load variations. As an attempt to apply the passivity-based framework to the converter with parasitic resistance we have combined a new proportional-integral (PI) controller with the PBC. Simulation results show that the combined (PBC and PI) dynamic output feedback controller successfully achieves the performance improvement under reference step changes and load variations.
This paper compares four assembly solutions for power converters operating in sealed enclosures with tight temperature specifications. The specific application of interest is one of the DC/DCconverters of a power supply system to be used in high-energy-physics experiments: the sealed case must not significantly alter the temperature of the surrounding components (detectors and their electronics). The comparison is made using 3D Finite Element thermal modeling. The standard FR4 board solution is shown not to be viable under these tight temperature specs; we therefore explore alternative assemblies for the stack connecting the active devices to the heat-sink.
A new on-chip current sensing circuit suitable for step-down switch-mode power converters (SMPC) is presented in this paper. It can be used in a high speed SMPC. The sense voltage is quite accurate and temperature independent. The structure is very simple. Only eight transistors and a sensing resistor are used. This current sensing technique has been fabricated with a standard 0.5µm DPDM CMOS process. Experimental results show that the proposed circuit can work well in DC-DCconverters such that the loading current can be managed through control theories.
A new on-chip current sensing circuit suitable for step-down switch-mode power converters (SMPC) is presented in this paper. It can be used in a high speed SMPC. The sense voltage is quite accurate and temperature independent. The structure is very simple. Only eight transistors and a sensing resistor are used. This current sensing technique has been fabricated with a standard 0.5µm DPDM CMOS process. Experimental results show that the proposed circuit can work well in DC-DCconverters such that the loading current can be managed through control theories.
This paper presents a new boost dc-dcconverter with high efficiency by using a partial resonant circuit. The switching devices in the proposed converter are operated by a soft-switching technique (ZCS; zero current switching, or ZVS; zero voltage switching) of a new partial resonant circuit. The partial resonant circuit makes use of a step-up inductor and a loss-less snubber capacitor. The switching control technique is simplified for the switches to drive in constant switching frequency with PWM (pulse width modulation). The results are that the switching power loss is very low and the system efficiency is high.
Battery/Ultra-capacitor based electrical vehicles (EV) combine two energy sources with different voltage levels and current characteristics. This paper focuses on design and control of a multiple input DC/DCconverter, to regulate output voltage from different inputs. The proposed multi-input converter is capable of bi-directional operation and is responsible for power diversification and optimization. A fixed switching frequency strategy is considered to control its operating modes. A portion of New York City Cycle that includes these operation modes is used to perform the analyses.
This paper presents a new non-insulated three-level DC-DC boost converter with quadratic static gain. The quadratic feature is interesting for applications where a wide voltage range is necessary. The voltage across the switches is smaller then the output voltage. Since it is a current-source converter, its application in fuel cell energy conversion systems seems interesting, but other applications where the involved voltages are higher is very possible. Theoretical analysis for CCM of operation and experimental results are presented. A comparison between the two cascaded boost converter, the single switch quadratic boost converter and the proposed converter is made regarding commutated power. By experimental results is shown that the efficiency of the proposed converter is higher than two cascaded boost converters, even with less installed semiconductor power.
This paper presents a new grid connected inverter for fuel cells. It consists of a two stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25 V-45 V) this volt- age must be transformed to around 350-400 V in order to invert this dc power into ac power to the grid. The proposed converter consists of an isolated dc-dcconverter cascaded with a single phase H-bridge inverter. The dc-dcconverter is a current-fed push-pull converter. A new dedicated voltage mode startup procedure has been developed in order to limit the inrush current during startup. The inverter is controlled as a power factor controller with resistor emulation.Experimental results of converter efficiency, grid performance and fuel cell response are shown for a 1 kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92%) and the inverter operates with a near unity power factor and a low current THD.
A new "model-free" control methodology is applied for the first time to power converters, and in particular to a buckconverter, and to a Cuk converter. We evaluate its performances regarding load and supply variations. Our approach, which utilizes "intelligent" PI controllers, does not require any ...
The conventional grid-connected photovoltaic (PV) inverter that steps up low DC voltage to high DC voltage and cascades with the high frequency inverter is complicated in control and of low efficiency due to two stages. This paper presents a novel PV inverter system formed by a hybrid DC-DCconverter and a full-bridge DC-AC converter. The hybrid DC-DCconverter combines the boost and flyback topologies to produce a semi-sinusoidal output current and to achieve the high step-up objective. A full-bridge DC-AC converter controlled with low-frequency switching techniques is then used to convert the current into sinusoidal form and to feed power to the grid with unity power factor. The overall efficiency of the designed system is high due to the losses of both stages are reduced. In this paper, the circuit operating theory of the proposed PV inverter is firstly addressed then an 80W prototype system is designed and built. The feasibility and effectiveness of the proposed circuit are confirmed with some simulation and experimental results.
Abstract This paper proposes a new circuit topology for a high-efficiency isolated DC/DCconverter using series compensation. The proposed converter consists of a high-efficiency resonance half-bridge converter and a series converter. The series converter regulates the output voltage and provides only the differential voltage between the input voltage and output voltage. Therefore, the circuit achieves high efficiency when the input voltage is almost equal to the output voltage, because then only the resonance converter will operate. In this paper, the approach employed to achieve high efficiency by using the proposed series compensation method is introduced. In addition, the fundamental operation and the method of designing the proposed circuit are described. The suitability of the propos...
Abstract in spanish Este trabajo propone el análisis y diseño de dos estrategias de control para un conversor CC-CC reductor de corriente permanente. Tal tipo de dispositivos de electrónica de potencia convierten una tensión continua a otra de menor magnitud y cuyas características de no linealidad son evidenciadas. Se presentan entonces, dos técnicas de control no lineal, la primera propuesta es un control óptimo PI (error proporcional e integral del error) convencional, basado en la (more) minimización del criterio ITSE (integral del cuadrado del error ponderado en el tiempo). Para ello se obtiene un modelo de la planta en un punto de operación. La segunda propuesta es un control difuso cuyos conjuntos de entrada y salida son también definidos minimizando el criterio ITSE en el sistema general, y estableciendo como entradas el error proporcional y la integral del error. A continuación se realiza una variación de la carga para establecer la eficiencia del sistema con los dos controladores mencionados. Se debe tener en cuenta que este tipo de sistemas no debe presentar sobretensiones considerables, ya que puede ocasionar daño en él. En este sentido, los parámetros encontrados en el diseño de los dos controladores corresponden a una metodología analítica y descriptiva. Los resultados obtenidos en simulación, y estableciendo como figura de mérito el índice de desempeño mencionado (ITSE) y el consumo de potencia, muestra que la respuesta del sistema para el control difuso presenta un mayor consumo de potencia que el control óptimo, mientras que el ITSE obtenido es mayor para el control óptimo que para el difuso. Se concluye que la exploración de este tipo de conversores, utilizando técnicas de control no lineal y minimizando los diferentes índices de desempeño, es aplicable. Abstract in english This document proposes analysing and designing two control strategies for permanent current DC-DCbuckconverter. These kinds of electronic devices convert a constant-voltage to a lower constant-voltage (nonlinearity characteristics being demonstrated). Two nonlinear control techniques are shown. The first is a conventional optimal proportional error and integral error (PI) controller based on minimising integral of time per squared errors (ITSE) criteria. A model of the (more) plant at an operation point was thus obtained. The second one was fuzzy control where input and output sets were also defined by minimising ITSE criteria in the overall system and establishing inputs such as proportional error and integral error. Load was then varied to establish the system's efficiency with both the aforementioned controllers. It must be borne in mind that such systems should not present supervoltage since this can cause damage. The parameters found in designing both controllers thus corresponded to analytical and descriptive methodology. Simulation results, the performance index mentioned above (ITSE) and power consumption showed that the system's response for the fuzzy control drew more power consumption than the optimal controller; otherwise, obtained ITSE was larger for the optimal control than the fuzzy control. It is concluded that exploring these types of converter is applicable when using nonlinear control techniques and minimising the different performance indices.
A plasma ignition system for an internal combustion engine having a plasma ignition plug within each of the engine cylinders, which comprises: (a) a low DC voltage supply such as a vehicle battery; (b) a high surge voltage generator which generates and distributes a high surge voltage having a negative peak value of about minus 15 kilovolts into one of the plasma ignition plugs according to a predetermined ignition order so as to generate a spark discharge at the plasma ignition plug; (c) a DC-DCconverter which boosts the low DC voltage sent from the low DC voltage supply to a high DC voltage; (d) a plurality of plasma ignition energy charging means each of which charges the high DC voltage supplied from the DC-DCconverter; (e) a plurality of thyristors each for connecting the plasma ignition energy charging means to the corresponding plasma ignition energy charging means to the corresponding plasma ignition plug in response to a first trigger signal applied thereat; (f) a trigger signal generator which generates and outputs the first trigger signal into the gate terminal of one of the thyristors according to the predetermined ignition order so as to turn on said thyristor and a second trigger signal for halting the high DC voltage from outputting from the DC-DCconverter; (g) a plurality of inductors for producing an oscillation on a basis of the high DC voltage outputted from the corresponding plasma ignition energy charging means; and (h) a high DC voltage charging and discharging means for extending the turn-on interval of one of the thyristors which is triggered by the first trigger signal from the trigger signal generator, whereby the plasma ignition always occurs without misfire.
In this paper three dc/dcconverter topologies suitable for high-power-density high-power applications are presented. All three circuits operate in a soft-switched manner, making possible a reduction in device switching losses and an increase in switching frequency. The three-phase dual-bridge converter proposed is seen to have the most favorable characteristics. This converter consists of two three-phase inverter stages operating in a high-frequency six-step mode. In contrast to existing single-phase ac-link dc/dcconverters, lower turn-off peak currents in the power devices and lower rms current ratings for both the input and output filter capacitors are obtained. This is in addition to smaller filter element values due to the higher-frequency content of the input and output waveforms. Furthermore, the use of a three phase symmetrical transformer instead of single-phase transformers and a better utilization of the available apparent power of the transformer (as a consequence of the controlled output inverter) significantly increase the power density attainable.
Aspects of power electronics are addressed. The general topics discussed include: inverters and converters, modelling and analysis, motor drives, power conditioning appliances, power semiconductor devices, and power components and protection. Individual subjects considered include: dual-mode forward/flyback converter; a solar cell power supply system using a boost-type bidirectional DC-DCconverter; complete DC analysis of the series resonant converter; variable structure control with sliding mode for DC drive speed regulation; a low-cost single-phase induction generator. Also covered are: small-signal modelling of a push-pull current-fed converter; programmable power processor for high-power space applications; high efficiency 3kW switch mode battery charger; comparison of BIMOS device types; power MOSFET temperature measurements; protection of power transistors in electric vehicle drives; general purpose variable frequency inverter using integrated power modules and LSI. For individual items see A84-18377 to A84-18408
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/dcconverters 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 is to minimize the input admittance in order to make the grid converter more robust to grid disturbance.
In this paper, a novel isolated current-fed DC-DCconverter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy, the proposed converter can draw power from two different DC sources with lower voltage and deliver it to the higher voltage DC bus or load individually and simultaneously. The detailed operation principle of the proposed converter has been analyzed in dual-input mode and single-input mode, respectively. Furthermore, the method to increase the number of input ports, the magnetic integration structure, and ground loop decoupling are discussed. Experimental results from the lab prototype converter with two DC voltage sources verify the validity of the theoretical analysis and design of the converter.
Due to the increased use of renewable energy and power elctronic applications, more multilevel converters (MLC) are developed. A Neutral Point Clamped (NPC) inverter is one of the most used multilevel topologies for wind turbine (WT) and photovoltaic (PV) applications. One of the most crucial points in this type of converter is dc-voltage control. In this paper, a novel multi output dc-dcconverter connected to a diode clamped topology is presented. This converter, for a given duty cycles, is able to regulate the capacitor voltage to provide an appropriate input voltage for NPC regardless of load changes which can avoid neutral point balancing problem in such converters. In addition, the presented topology is suitable for renewable energy systems to boost the low rectified output-voltage. In order to verify the proposed topology, steady state analysis, modelling and simulations are carried out.
A hysteresis-current-controlled (HCC) buckconverter with active current-sensing and phase-frequencylocked techniques is presented in this paper. The proposed active current-sensing technique can not only consume less power than previous techniques, but also fully sense the inductor current. Although the buckconverter is HCC, the switching frequency can be constant due to the devised phase-frequency-locked technique. The proposed converter has been designed and implemented with TSMC 0.35 microm DPQM CMOS processes. It is shown in the experimental results that the HCC buckconverter features the following characteristics: 1) up to 800 mA of load current, 2) wide input and output voltage range, 3) high power efficiency, and 4) constant-frequency operation. PMID:18467220
The design, implementation and testing of a purely super-capacitors energy storage system for automotive system having a fuel cell as main source are presented. The system employs a super-capacitive storage device, composed of six components (3500 F, 2.5 V, 400 A) associated in series. This device is connected to automotive 42 V DC bus by a 2-quadrant DC-DCconverter. The control structure of the system is realised by means of analogical and digital control. The experimental results show that super-capacitors are suitable as energy storage device for fuel cell automotive electrical system. (authors)
Abstract Conventional cell/module voltage equalizers or equalization chargers based on traditional DC-DCconverters require numerous switches or transformers as the number of series connections increases; therefore, their cost and complexity tend to increase and their reliability decreases as the number of connections increases. This paper proposes a novel voltage equalization charger that consists only of passive components such as capacitors, diodes, and a transformer. The fundamental operating principle, major features, and derivation of equivalent DC circuits are presented. A symmetrical configuration is also proposed to mitigate the RMS current flowing through energy storage cells in the charging process. Simulations and experimental charging and cycle tests were performed on series-c...
Plug-In Hybrid Electric Vehicles (PHEV) require high power density energy storage system (ESS) for hybrid operation and high energy density ESS for Electric Vehicle (EV) mode range. However, ESS technologies to maximize power density and energy density simultaneously are not commercially feasible. The use of bi-directional DC-DCconverter allows use of multiple energy storage, and the flexible DC-link voltages can enhance the system efficiency and reduce component sizing. This will improve fuel consumption, increase the EV mode range, reduce the total weight, reduce battery initial and life cycle cost, and provide flexibility in system design.
This paper describes how mixed signal controllers combining a cheap microcontroller with a simple analogue circuit can offer high performance digital control for DC/DCconverters. Mixed signal controllers have the same versatility and performance as DSP based controllers. It is important to have an engineer experienced in microcontroller programming write the software algorithms to achieve optimal performance. Two mixed signal controller designs based on the same 8-bit microcontroller are compared both theoretically and experimentally. A 16-bit PID compensator with a sampling frequency of 200 kHz implemented in the 16 MIPS, 8-bit ATTiny26 microcontroller is demonstrated.
This paper will review the development of SiC power devices especially SiC power junction field-effect transistors (JFETs). Rationale and different approaches to the development of SiC power JFETs will be presented, focusing on normally-OFF power JFETs that can provide the highly desired fail-save feature for reliable power switching applications. New results for the first demonstration of SiC Power ICs will be presented and the potential for distributed DC-DC power converters at frequencies higher than 35MHz will be discussed.
High-frequency ripple (spike noise) effects in the qualitative properties of DC/DCconverter circuits. This study investigates the bifurcation structure of a chaotic attractor in a switched dynamical system with spike noise. First, we introduce the system dynamics and derive the associated Poincare map. Next, we show the bifurcation structure of the chaotic attractor in a system with spike noise. Finally, we investigate the dynamical effect of spike noise in the existence region of the chaotic attractor compare with that of a chaotic attractor in a system with ideal switching. The results suggest that spike noise enlarges an invariant set and generates a new bifurcation structure of the chaotic attractor.
This paper presents the analysis and design procedures of a new dc-dc full bridge PWM converter, using the ZVS-PWM communication cell to achieve soft switching. Experimental results obtained from a laboratory prototype rated 1500 W are also presented. It is demonstrated that the inclusion of the auxiliary switches do not modify the PWM switching pattern. Bench tests on the prototype confirm that the proposed circuit exhibits high efficiency and behaves as a constant voltage source over an extended power output range. (author) 8 refs., 9 figs.
A passivity based sliding mode control is proposed which achieves the output feedback stabilization of a realistic model of a switch-mode dc-dc power converter of the boost type. The possibilities of using a state observer of discontinuous nature is also explored in detail. Suitable `damping injections` and `energy shappings` are shown to be independently accomplished, via discontinuous feedback and discontinuous feed-forward output injections, for both the regulated plant and the sliding mode observer error dynamics respectively. (author) 10 refs., 1 fig.
A DC-DCconverter capable of generating outputs of 100 KV without a transformer comprises a silicon opening switch (SOS) diode connected to allow a charging current from a capacitor to flow into an inductor. When a specified amount of charge has flowed through the SOS diode, it opens up abruptly; and the consequential collapsing field of the inductor causes a voltage and current reversal that is steered into a load capacitor by an output diode. A switch across the series combination of the capacitor, inductor, and SOS diode closes to periodically reset the SOS diode by inducing a forward-biased current.
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.
This work presents a buck-boost zero-current-switched pulse width modulated quasi-resonant converter (buck-boost QRC-ZCS-PWM) using unidirectional current switch operating with high power factor. The input stage is controlled using a boost zero-current-switched pulse width modulated quasi-resonant converter with unidirectional current switch. In this stage the current is controlled in a sinusoidal way with zero displacement from the input voltage. This control is made using a IC 3524. A prototype was bread-boarded and the experimental results obtained. These results were compared with the theoretical results and the quasi-resonant converter proved to be a good choice. (author) 5 refs., 14 figs., 1 tab.
Based on a detailed study of the radiation tolerance of high-voltage transistors, 2 commercial CMOS technologies have been selected for the design of synchronous buck DCDC converter ASICs. Three prototype converters have been produced, embedding increasingly sophisticated functions. The electrical and radiation performance of these prototypes is presented.
In this paper, an interleaved multiphase buckconverter with minimum time control strategy for envelope amplifiers in high efficiency RF power amplifiers is proposed. The solution for the envelope amplifier is to combine the proposed converter with a linear regulator in series. High efficiency of en...
This paper proposes an interleaved multiphase buckconverter with minimum time control strategy for envelope amplifiers in high efficiency RF power amplifiers. The solution of the envelope amplifier is to combine the proposed converter with a linear regulator in series. High system efficiency ca...
A common limitation of power coupling effect in some known multiple-input dc-dcconverters has been addressed in many literatures. In order to overcome this limitation, a new concept for decoupling the primary windings in the integrated multiple-winding transformers based on 3-dimensional (3D) space orthogonal flux is proposed in this paper. And thus a new geometry core and relative winding arrangements are proposed in accordance with the rthogonal flux decoupling technology. Due to the four secondary windings are arranged in a quadratic pattern at the base core plate with the two perpendicular primary windings, a name of “four quadrants integrated transformers” (FQIT) is therefore given to the proposed construction. Since the two primary windings are uncoupled, the FQIT allows the two input power stages to transfer the energy into the output load simultaneously or at any timemultiplexing scheme, which can optimize the utilization of diversified power energy sources, simplify the system structure, improve the flexibility and reduce the overall cost, so they are attractive for the hybrid renewable power system. Section IV initiates a discussion for the advantages of the FQIT. In order to verify the feasibility of the FQIT in multiple-input converter, a dual-input isolated boost dc-dcconverter employing with the FQIT is designed and tested. The results have excellently demonstrated that the two input power stages can be operated independently and the correctness of all the analysis in the paper.
In this paper, a design procedure for photovoltaic/wind hybrid power generation system is presented. The hybrid system is composed of a DC/DCconverter for a photovoltaic energy conversion, a DC/DCconverter for a wind energy conversion, a four switch IGBT inverter converting the combined DC power to the AC power and a backup power battery. Here, it is very important to select the desired battery size to meet the stable output and economic cost aspect since this system utilizes fluctuating and finite energy resource. The purpose of this paper is to develop a sizing method for the PV/Wind energy hybrid system with load sharing operation. The method demonstrates a simple tool to determine the desired battery size that satisfies the energy demand from the user with the photovoltaic and wind natural source. The proposed method is verified on a 14kW hybrid power system including a 10kW PV generator and a 4kW wind generator established in Cheju island, Korea.
Systems that harvest or scavenge energy from their environments are of considerable interest for use in remote power supplies. A class of such systems exploits the motion or deformation associated with vibration, converting the mechanical energy to electrical, and storing it for later use; some of these systems use piezoelectric materials for the direct conversion of strain energy to electrical energy. The removal of mechanical energy from a vibrating structure necessarily results in damping. This research addresses the damping associated with a piezoelectric energy harvesting system that consists of a full-bridge rectifier, a filter capacitor, a switching DC-DC step-down converter, and a battery. Under conditions of harmonic forcing, the effective modal loss factor depends on: (1) the electromechanical coupling coefficient of the piezoelectric system; and (2) the ratio of the rectifier output voltage during operation to its maximum open-circuit value. When the DC-DCconverter is maximizing power flow to the battery, this voltage ratio is very nearly 1/2, and the loss factor depends only on the coupling coefficient. Experiments on a base-driven piezoelectric cantilever, having a system coupling coefficient of 26%, yielded an effective loss factor for the fundamental vibration mode of 2.2%, in excellent agreement with theory.
In this paper, a Dickson-type power converter with bootstrapped gate transfer switches is proposed. The circuit is designed by adding a polarity exchange circuit and N (N=2, 3, ...) power-switches to the conventional Dickson-type circuit. These additional circuits enable the converter to provide not only a DC-DC output but a DC-AC output. In the process of DC-AC conversion, the circuit can generate various AC outputs by exploiting pulse amplitude modulation (PAM) method. Furthermore, high efficiency can be achieved by adopting novel bootstrap circuits to power-switches in the converter. Via maximum circuits constructed with diodes, the voltage of forward stage is charged to a capacitor in the bootstrap circuit. By connecting the charged-capacitor between the gate terminals of power-switches and the output terminal of the maximum circuit, the bootstrap circuits reduce the on-resistance of the power-switches. The SPICE simulations for the proposed circuit show the following results: 1. the voltage efficiency of DC-DC conversion is more than 90 % when the output load Ro = 500? and 2. various types of AC outputs can be generated.
This paper proposes a novel phase-shift plus duty cycle controlled hybrid bi-directional DC-DCconverter based on fuel cells and supercapacitors. The described converter employs two high frequency transformers to couple the half-bridge and full-bridge circuits together in the primary side and voltage doubler circuit in secondary side. Boost type converter can limit the output ripple current of the fuel cells; hybrid full-bridge structure can change operating modes according to the different input voltage; phase-shift with duty cycle control scheme is utilized to control the bidirectional power flow flexibly. All the switches can turn on under zero-voltage-switching condition (ZVS). The operating principles of the converter are described in details, and the experimental results based on the prototype controlled by DSP are presented to verify the validity of the analysis and design.
This paper presents a low-cost bidirectional isolated dc–dcconverte, derived from dual-active-bridge converter for the power sources with variable output voltage like supercapacitors. The proposed converter consists of push-pull-forward circuit half-bridge circuit (PPFHB) and a high-frequency transformer; this structure minimizes the number of the switching transistors and their associate gate driver components. With phase-shift control strategy, all the switches are operated under zero-voltage switching (ZVS) condition. Furthermore, in order to optimize the converter performance and increase efficiency, optimal design methods and criteria are investigated, including coupled inductors design, bidirectional power flow analysis, harmonics analysis, and ZVS range extension. Based on all the optimal parameters, higher efficiency can be achieved. Finally, prototypes are built in laboratory controlled by digital signal processor for comparison purpose. Detailed test results verify the theoretical analysis and demonstrate the validity of optimization design method.
This paper describes the analysis and design of a DC-DCconverter topology which is operational at frequencies in the Very High Frequency (VHF) band ranging from 30 MHz ? 300 MHz. The presented topology, which consists of a class E inverter, class E rectifier, and self-oscillating gate driver, is inherently resonant, and switching losses are greatly reduced by ensuring Zero Voltage Switching (ZVS) of the power semiconductor devices. A design method to ensure ZVS operation when combining the inverter, rectifier, and gate driver is provided. Several parasitic effects and their influence on converter operation are discussed, and measurement results of a 100 MHz prototype converter are presented and evaluated. The designed prototype converter verifies the described topology.
There are many applications for high gain dc-dcconverters. In several of these applications galvanic isolation is not required, but there are some safety issues regarding missing isolation and leakage current. Usage of a half-bridge inverter and a dual dc-link may solve this issues. In this paper very simple dual output non-isolated boost converter is presented. Single active switch is used to control both, positive and negative output voltages. The converter is desired to boost unregulated low input voltage 25-50 Vdc to regulated high voltage ±400 Vdc in dual dc-link. In this paper proposed topology is analyzed and explained. Obtained experimental results prove good performance of the converter over wide range of input voltage and output power.
Soft-switching phase-shifted PWM converters have been attracted much attention because of their low switching losses, constant frequency operation and simple control. However, a circulating current flows through the transformer and the primary bridge circuit during the freewheeling interval, resulting in relatively high current stresses for the transformer and switching devices compared with those of conventional hard-switching PWM converters. This paper presents an improved soft-switching PWM DC-DCconverter which can substantially reduce the circulating current by employing a tapped inductor for output low-pass filter. The principle of operation and the role of the tapped inductor are illustrated. The effectiveness of the tapped inductor is evaluated through simulating analysis. Moreover, a 500W-100kHz prototype converter is implemented to demonstrate the excellent performances of both low switching and low conduction losses. 11 refs., 12 figs.
Abstract The two-switch flyback DC-DCconverter is an extended version of the conventional single-switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single-switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two-switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed analysis and design procedure of the diode-clamped two-switch flyback converter operated in discontinuous-conduction mode (DCM). A comparison of power losses of the two-switch and the single-switch flybac...
Abstract A new two-transformer active-clamping forward converter with parallel-connected current doubler rectifiers (CDRs) is proposed in this paper. The presented DC-DCconverter is mainly composed of two active-clamping forward converters with secondary CDRs. Only two switches are required and each one is the auxiliary switch for the other. The circuit complexity and cost are thus reduced. The leakage inductance of the transformer or an additional resonant inductance is employed to achieve zero-voltage-switching (ZVS) during the dead times. Two CDRs at the secondary side are connected in parallel to reduce the current stresses of the secondary windings and the ripple current at the output side. Accordingly, the smaller output chokes and capacitors decrease the converter volume and increa...
Abstract The two-switch flyback DC-DCconverter is an extended version of the conventional single-switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single-switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two-switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed steady-state analysis and design procedure of the diode-clamped two-switch flyback converter operated in continuous-conduction mode (CCM). The power loss in each component of the two-switch flyback conver...
This paper deals with the design of controllers for the boost dc-dcconverter applied to active power factor correction. The study of three kinds of controllers for the current loop (inner loop) and three more for the converter output voltage loop (outer loop) are presented. In order to verify the theoretical results a prototype rated at 1500 W (nominal power) were built-up and tested. The converter behavior and performance for closed loop operation with some of controllers proposed were verified. The most important results and conclusions concerning the converter operation, as well as a straightforward procedure for the design of the proposed controller, are presented and commented at the end of the present report. (author) 9 refs., 9 figs., 2 tabs.
In this paper, a high accuracy, high efficiency, and wide current-sensing range current-mode PWM buckconverter with on-chip current-sensing technique is presented. The proposed current-sensing circuit uses simple switch technique to achieve high accuracy, high power efficiency, and high line regulation. The test chip is fabricated using TSMC 0.18µm 1P6M 3.3V CMOS process. The measurement results show that the buckconverter with on-chip current-sensing circuit can operate from 700kHz to 3MHz with a supply voltage of 1.5-5V and the output voltage of 0.5-4.5V for lithium ion battery applications. The accuracy of the proposed current-sensing circuit is exceeds 89.8% for load current from 50mA to 500mA and for temperature from 0°C to 100°C. The peak power efficiency of the buckconverter is up to 95.5%.
In this paper, a high accuracy, high efficiency, and wide current-sensing range current-mode PWM buckconverter with on-chip current-sensing technique is presented. The proposed current-sensing circuit uses simple switch technique to achieve high accuracy, high power efficiency, and high line regulation. The test chip is fabricated using TSMC 0.18µm 1P6M 3.3V CMOS process. The measurement results show that the buckconverter with on-chip current-sensing circuit can operate from 700kHz to 3MHz with a supply voltage of 1.5-5V and the output voltage of 0.5-4.5V for lithium ion battery applications. The accuracy of the proposed current-sensing circuit is exceeds 89.8% for load current from 50mA to 500mA and for temperature from 0°C to 100°C. The peak power efficiency of the buckconverter is up to 95.5%.
This paper deals with the problem of the analysis of boost and buckconverters at the steady state with the use of the method of average models. The usefulness of this method is examined by comparing the boost and buckconverters characteristics at the steady-state obtained both with the transient analysis with physical models of semiconductor devices and the examined method as well. The accuracy of the method of the average models is investigated with respect to the values of the circuit load resistance, the pulse-duty factor and the frequency of the signal controlling the power switch. Copyright Copyright 2009 John Wiley & Sons, Ltd.
This paper presents a buckconverter with a switch-on-demand modulator (SOM) for achieving a fast transient response, small voltage ripple, and high power efficiency over a wide load range. Switching power MOS on or off depending on the energy demand of the load circuit results in a hybrid operation of pulse width modulation (PWM) and pulse frequency modulation (PFM). The proposed buckconverter uses 90nm CMOS process and can achieve a transient response time of less than 2µs and a voltage ripple of 18mV at a load current range of 10mA?500mA with a power efficiency above 88%.
This paper shows a loss-less commutation cell that uses a non-linear resonant inductor. The principle of the non-linear resonant inductor is applied to a QRC-ZCS-PWM buckconverter with objective of reducing the peak current in the main switch, maintaining the ZCS characteristics of the QRC-ZCS-PWM buckconverter. This is achieved by un-saturating the core of the non-linear resonant inductor limiting its peak value. Mathematical equations, circuit operation and experimental results are also presented 4 refs., 16 figs., 1 tab.
This work deals with the performances and responses of a grid-connected photovoltaic (PV) plant in normal and disturbed modes. The system is composed of a solar array, a dc-dcconverter and a three-phase inverter connected to the utility grid. On the one hand a suitable control of the dc-dcconverter is developed in order to extract the maximum amount of power from the PV generator. On the other hand an active and reactive power control approach (PQ) has been presented for the inverter. This method can provide a current with sinusoidal waveform and ensure a high power factor. Therefore, the grid interface inverter transfers the energy drawn from the PV into the grid by ensuring constant dc link voltage. Modeling and controlling were carried out using the informational graph of causality and the macroscopic energy representation methods. The simulation under MATLAB/SIMULINK and the experimental results show the control performance and dynamic behavior of grid-connected PV system in normal and disturbances modes. (author)
Abstract in spanish Este artículo propone un pre-amplificador basado en convertidores DC-DC conectados en paralelo para la reducción de armónicos inyectados a fuentes de potencia. Las principales características del pre-amplificador son la reducción del rizado de corriente de entrada en convertidores de potencia, incrementado además la eficiencia del sistema de conversión. Se describe el cálculo de las condiciones óptimas de operación del pre-amplificador, así como su modelado mat (more) emático y control para operar en las condiciones seleccionadas. Así mismo, se analiza el pre-amplificador con un convertidor elevador clásico, obteniendo una reducción significativa en el rizado de corriente inyectado a la fuente, así como un incremento en la eficiencia del sistema. Finalmente, los análisis teóricos se confirman a través de simulaciones circuitales y resultados experimentales. Abstract in english An efficient pre-amplifier based on interleaved DC-DC boost switching converters to mitigate high-frequency harmonics injection to power sources is proposed. The main features of the pre-amplifier are mitigate the ripple of power converters input-current and improving the efficiency of the whole power conversion chain. The pre-amplifier optimal operating conditions are calculated, and the circuit is modeled and controlled to operate in such conditions. The pre-amplifier i (more) nteracting with a classical single boost is analyzed, obtaining a strong reduction in the current ripple injected to the source, and also improving the efficiency of the initial conversion system. Finally, the theoretical analyses are confirmed by means of circuital PSIM simulations and experimental results.
Conference paper.See also ADA548241. Annual Conference of the Prognostics and Health Management Society (PHM 2010) Held in Portland, Oregon on October 10- 14, 2010. U.S. Government or Federal Purpose Rights License., The original document contains color images.Understanding the ageing mechanisms of electronic components critical avionics systems such as the GPS and INAV are of critical importance. Electrolytic capacitors and MOSFET's have higher failure rates among the components of DC-DC power converter systems. Our current work focuses on analyzing and modeling electrolytic capacitor degradation and its effects on the output of DC-DCconverter systems. The output degradation is typically measured by an increase in ESR (Equivalent Series Resistance) and decrease in the capacitance value over long periods of use even under nominal operating conditions. Typically the primary effect of degradation is increased ripple current and this has adverse effects on downstream components. For example, in avionics systems where the power supply drives a GPS unit, ripple currents can cause glitches in the GPS position and velocity output, and this may cause errors in the Inertial Navigation (INAV) system, causing the aircraft to fly off course. In this paper, we present the details of our ageing methodology along with details of experiments and analysis of the results.
This thesis focuses on the development of a fuel cell-based hybrid electric powertrain for smaller (2 kW) hybrid electric vehicles (HEVs). A Hardware-in-the-Loop test rig is designed and built with the possibility to simulate any load profile for HEVs in a realistic environment, whereby the environment is modeled. Detailed simulation models of the test rig are developed and validated to real physical components and control algorithms are designed for the DC/DC-converters and the fuel cell system. A state-feedback controller is developed for the DC/DC-converters where the state-space averaging method is used for the development. For the fuel cells, a gain-scheduling controller based on state feedback is developed and compared to two conventional methods. The design process of an HEV with regard to a given load profile is introduced with comparison between SuperCaps and batteries. The HEV is also evaluated with an introduction to different power management concepts with regard to fuel consumption, dynamics, and fuel cell deterioration rate. The power management methods are implemented in the test rig and compared. (orig.)
In recent years, various countermeasures have been studied to reduce the switching loss caused by the application of higher frequencies in high-frequency link DC-DCconverters. In this report, regarding a flyback-system as of high-frequency link DC-DCconverters and from a viewpoint of soft switching, the steady-state zero current switching (ZCS) operation characteristics as well as the starting switching operation duty in the transient-state were investigated with a comparison in contrast between the result of numerical analysis and the experimental result. As a result, the steady-state ZCS operation region was elucidated in the normalized [mu] -[lambda] plane for soft switching. Furthermore, not only a ZCS operation on the active main switch but also a zero voltage switching operation at turn off were clarified to be feasible in a ZCS operation boundary region. Also, as the characteristics of steady-state ZCS operation output were made clear: in relation to the normalized frequency and load, guidelines for output voltage regulation were presented. 6 refs., 16 figs., 1 tab.
This paper focuses on the production of electricity using a thermoelectric generator placed on the human body connected to a dc-dcconverter. The small difference in temperature between the hot heat source (e.g. the human body, Tb = 37 °C) and the cold heat source (e.g. ambient air, Ta = 22 °C), associated with a poor quality thermal coupling (mainly with the cold source), leads to a very low temperature gradient at the thermoelectric generator terminals and hence low productivity. Under these use conditions, the present article proposes an analysis of various ways to improve productivity given a surface capture system. Furthermore, we demonstrated, in this particular context, that maximizing the recovered electric power proves to be a different problem from that of maximizing efficiency, e.g. the figure of merit Z. We therefore define a new factor ZE, depending on the physical characteristics of thermoelectric materials, that maximizes electric power in the particular case where the thermal coupling is poor. Finally, this study highlights the benefit of sub-optimization of the power extracted from the thermoelectric generator to further improve efficiency of the overall system. We show that, given the conversion efficiency of the dc-dcconverter, the maximum power point of the overall system is no more reached when the output voltage of the thermoelectric generator is equal to half of its electromotive force.
Ultracapacitors or double layer capacitors are a recent technology based on the well-known electrochemical phenomenon of extremely high capacitance/unit area in an electrode-electrolyte interface and the high surface area achievable in activated carbon fibers. Capacitors have been tested with a rated capacitance value of 470 F and a rated voltage of 2.3 V. Test voltages as high as 3V (30% above rated) have been used without any short term effect on measured capacitance. At 3 V the total energy storage capacity of one capacitor is 2,100 Joules. With a total volume of 245 cm{sup 3}, the specific energy of this capacitor is 8.5 J/cm{sup 3}. To tap this entire energy store would require running the capacitor to zero voltage. Of course, few loads to which a capacitor bank might be connected can tolerate any drop in input voltage. To remedy this problem a DC/DCconverter between the capacitor bank and load is proposed. This paper describes optimization of capacitor bank configurations when supplying a constant power load through a DC/DCconverter.
High-voltage dc power supplies are often required to operate with highly dynamic loads, such as arcs. A switch-mode dc power supply can offer significant advantages over conventional thyristor-based dc power supplies under such conditions. It can quickly turn off the supply to extinguish the arc, and it can quickly recover after the arc. It has a relatively small output filter capacitance, which results in small stored energy available to the arc. A 400-kW, 50-kV switch-mode dc power supply for an electron-beam gun that exploits these advantages was designed and tested. It uses four 100-kW, current-source-type dc-dcconverters with inputs in parallel and outputs in series. The dc-dcconverters operate at 20 kHz in the voltage regulator part and 10 kHz in the inverter, transformer, and output rectifier part of the circuit. Insulated gate bipolar transistors (IGBTs) are used as the power switches. Special techniques are used to protect the power supply and load against arcs and hard shorts. The power supply has an efficiency of 93%, an output voltage ripple of 1%, and fast dynamic response. In addition, it is nearly one-third the size of conventional power supplies.
A novel on-chip frequency compensation circuit for a voltage-mode control DC/DCconverter is presented. By employing an RC network in the two signal paths of an operational transconductance amplifier (OTA), the proposed circuit generates two zeros to realize high closed-loop stability. Meanwhile, full on-chip integration is also achieved due to its simple structure. Hence, the number of off-chip components and the board space is greatly reduced. The structure of the dual signal path OTA is also optimized to help get a better transition response. Implemented in a 0.5 ?m CMOS process, the voltage mode control DC/DCconverter with the proposed frequency compensation circuit exhibits good stability. The test results show that both load and line regulations are less than 0.3%, and the output voltage can be recovered within 15 ?s for a 400 mA load step. Moreover, the compensation components area is less than 2% of the die's area and the board space is also reduced by 11%. The efficiency of the whole chip can be up to 95%.
In this paper, an interleaved soft-switched active-clamped L-L type current-fed half-bridge isolated dc-dcconverter has been proposed. The L-L type active-clamped current-fed converter is able to maintain zero-voltage switching (ZVS) of all switches for the complete operating range of wide fuel cell stack voltage variation at full load down to light load conditions. Active-clamped circuit absorbs the turn-off voltage spike across the switches. Half-bridge topology maintains higher efficiency due to lower conduction losses. Soft-switching permits higher switching frequency operation, reducing the size, weight and cost of the magnetic components. Interleaving of the two isolated converters is done using parallel input series output approach and phase-shifted modulation is adopted. It reduce...
This paper presents a new method to improve light load efficiency and minimize output ripple of switched-capacitor (SC) DC/DCconverters. In order to improve light load efficiency, this paper proposes adaptive frequency modulation to scale down gate-drive losses as load current reduces. Adaptive duty cycle modulation is proposed to minimize output ripple as the converter works under different gain hopping mode. Furthermore, this work optimized switching frequency, the dead time of 2-phase non-overlapping clocks and switching transistor size for efficiency enhancement. A new compensation circuit is also proposed to make system stable. A transistor level implementation of the proposed SC converter in Chartered 0.35 ?m CMOS process is provided. Measurement results shows: maximum ripple voltag...
Among innovative conversion systems for alternative energy, Fuel Cells (FCs) are ideal in applications as distributed power generation or automotive. The connection of FCs to domestic or industrial loads requires a DC/AC converter also acting as a energy buffer to match the different dynamics of FCs and loads. In the last years, a new type of electrolytic capacitors called Super- Capacitors (SCs), has been designed using double layers technology. Such components are able to store more energy than electrolytic capacitors maintaining the capability to swap it at high power levels. Firstly, different solution used to connect SCs to a FC based conversion system are considered. Then, a comparison of bi-directional DC/DCconverters designed to manage SCs energy is performed. Finally, the converter design and a laboratory prototype of the adopted solution are reported. (authors)
This paper investigates the effect of several frequency modulation profiles on conducted-noise reduction in dc-dcconverters with programmed switching controller. The converter is operated in variable frequency modulation regime. Twelve switching frequency modulation profiles have been studied. Some of the modulation data are prepared using MATLAB software, and others are generated online. Moreover, all the frequency profiles have been designed and implemented using FPGA and experimentally investigated. The experimental results show that the conducted-noise spreading depends on both the modulation sequence profile and the statistical characteristics of the sequence. A substantial part of the manufacturing cost of power converters for telecommunication applications involves designing filters to comply with the EMI limits. Considering this investigation significantly reduces the filter size.
This paper introduces a family of ring-type switched-capacitor (SC) converters, which produces 0.75˜2.3 V outputs by being stepped-down from a 3.6 V input. The circuit consists of 2 series-connected DC-DC conversion blocks. Since the input voltage is converted twice by these blocks, the proposed circuit can provide more various types of output-voltages than conventional ring-type converters. Furthermore, the efficiency and the hardware-cost are improved since the number of driver circuits can be reduced. As an example, the circuit is designed with 17 types of output voltages in the range of 0.75˜2.3 V. The SPICE simulations show that the power efficiency is more than 80 % in the output current range from about 110 to 360 mA.
In this paper a modular power electronic transformer (PET) for feeding critical loads is presented. The PE-based transformer is a multi-cellular step-down converter that can directly connect to medium voltage levels on the primary side and provide a low voltage, highly stable interface for consumer applications. The presented structure consists of three stages: a cascaded H-bridge (CHB) rectifier, an isolation stage, and an output stage. The CHB rectifier serves as an active rectifier to ensure that the input current is sinusoidal, and it converts the high AC input voltage to low DC voltages. The isolated DC/DCconverters are then connected to the DC links and provide galvanic isolation between the HV and LV sides. Finally, a three-phase inverter generates the AC output with the desired am...
This paper investigates the effect of several frequency modulation profiles on conducted-noise reduction in dc-dcconverters with programmed switching controller. The converter is operated in variable frequency modulation regime. Twelve switching frequency modulation profiles have been studied. Some of the modulation data are prepared using MATLAB software, and others are generated online. Moreover, all the frequency profiles have been designed and implemented using FPGA and experimentally investigated. The experimental results show that the conducted-noise spreading depends on both the modulation sequence profile and the statistical characteristics of the sequence. A substantial part of the manufacturing cost of power converters for telecommunication applications involves designing filters to comply with the EMI limits. Considering this investigation significantly reduces the filter size.
This paper presents a design of buck-current-fed full-bridge zero current switching converters which are suitable for high-power high-voltage DC applications. This study shows the capability of incorporating the step-up transformer parasitic components to get the zero current turn-off characteristics for full-bridge switches. The buck stage of the converter uses pulse-width-modulation control to regulate the output voltage and the full-bridge stage operates at a constant on time mode to implement soft-switching commutations. In this study, the converter model is derived, and this model is implemented in an IsSpice circuit, which can reveal the transient characteristics of the converter. Steady state analysis of the converter is also presented. Finally, the simulation results of this converter for the application of coupled cavity traveling wave tube are given and major design issues are discussed.
A step-down DC-DCconverter with charge-average processes is proposed in this paper. The converter is designed by using switched-capacitor (SC) techniques. Different from conventional converters such as a series-parallel type power converter and a Dickson-type power converter, the ripple noise of the proposed converter is small, because the output voltage is always obtained irrespective of the states of the clock pulses. The output voltage of the proposed converter is expressed by (Q/P) × Vin (P ?{1, 2,..., N} and Q?{1, 2,..., N}). Furthermore, when the number of the capacitors is small, the hardware-cost for the proposed circuit is less than that for the conventional converters such as a series-parallel type power converter and a ring-type power converter. Concerning 3-stage power converters, SPICE simulations are performed to confirm the validity of the circuit design. For the input voltage 3.6 V, the power efficiency of the proposed circuit is 92.7 % in the output current about 320 mA.
A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dcconverter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dcconverter modules are phase activated such that for n modules, each module is activated equally 360.degree./n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load.
This paper describes the design and implementation of zero voltage transition (ZVT) pulse width modulated (PWM) bidirectional buck-boost converter. The simplicity of the control and the reduction of voltage and current stresses on the main switches are the main features of the proposed converter. The additional component of the converter consists of two auxiliary switches and coupled inductors. They provide a zero voltage switching condition for all switching elements regardless of the power flow direction, making the energy conversion highly efficient. The calculated efficiency of the suggested converter is more than 96% at full load in both buck and boost modes. In addition, the same auxiliary circuit can be used in other basic non-isolated bidirectional converters such as Cuk, Sepic/Zet...
The electricity produced by a thermoelectric generator (TEG) must satisfy the requirements of specific loads given the signal level, stability, and power performance. In the design of such systems, one major challenge involves the interactions between the thermoelectric power source and the power stage and signal-conditioning circuits of the load, including DC-DC conversion, the maximum power point tracking (MPPT) controller, and other power management controllers. In this paper, a survey of existing power electronics designs for TEG systems is presented first. Second, a flat, wall-like TEG system consisting of 32 modules is experimentally optimized, and the improved power parameters are tested. Power-conditioning circuitry based on an interleaved boost DC-DCconverter is then developed for the TEG system in terms of the tested power specification. The power electronics design features a combined control scheme with an MPPT and a constant output voltage as well as the low-voltage and high-current output characteristics of the TEG system. The experimental results of the TEG system with the power electronics stage and with purely resistive loads are compared. The comparisons verify the feasibility and effectiveness of the proposed design. Finally, the thermal-electric coupling effects caused by current-related heat source terms, such as the Peltier effect etc., are reported and discussed, and the potential influence on the power electronics design due to such coupling is analyzed.
Abstract in spanish El propósito de este artículo es presentar un análisis alternativo de circuitos conmutados para diseñar generadores de onda cuadrada, SWG (del Inglés Square Wave Generator). Un SWG puede ser diseñado usando componentes electrónicos de bajo costo, lo cual permite al lector comprender como los convertidores DC-DC y DC-AC basados en la aproximación conmutada es una opción económica para introducir conceptos del análisis de redes. Los resultados experimentales mues (more) tran que las técnicas usadas permiten calcular el rango de operación no solo de los componentes electrónicos sino también del efecto que el valor de la fuente de alimentación tiene en el desempeño de los generadores. Abstract in english The purpose of this paper is to present an alternative analysis of switched circuit to design square wave generators (SWG). A SWG may be designed by using low-cost electronic components, which allows to the readers to understand how DC-DC and DC-AC converters based on the switched approach is an economic option to introduce network analysis concepts. Experimental results show that used techniques allow calculate the frequency range operation not only of the electronic components but also the effect of the power supply value on the generators' performance.
Study is conducted of a photovoltaic/fuel-cell hybrid system whose power storage is a hydrogen storage that uses a hydrogen absorbing alloy. In a simulation in this research, the solar cell conversion efficiency is changed from 15.0% to 21.0% and the fuel cell power conversion efficiency from 40.0% to 50.0%, and the resultant changes in the capacity and operation rate are investigated for each of the devices in the system. The findings follow. A 1.0% change in the solar cell conversion efficiency results in a 4.8kW change in the solar cell capacity and a 1.6-ton change in the hydrogen storage capacity. With a 1.0% change in the fuel cell power conversion efficiency, there is a 14.7kW change in the solar cell capacity and a 5.3-ton change in the hydrogen storage capacity. The fuel cell capacity is not dependent on the solar cell conversion efficiency or fuel cell power conversion efficiency but on the maximum load in each of the load form factors. The rate of occurrence of an operation rate of less than 30% is 54.7% both in DC/DCconverter and hydrogen generator, 24.6% in fuel cells, and 16.7% in the DC/DC inverter. 7 refs., 7 figs., 1 tab.
Thanks to CO2 emission reduction policies and increasing prices of fossil fuels a significant growth in field of sustainable energy sources (SES) is being observed during last decade. A government support and take-off projects in Europe and US shall ensure an increasing trend in future too. Some of SES based plants , like hydro-, geothermal-, biofuel-plants, use synchronous generators directly connected to the grid. But some other SES technologies, like fuel cell or photovoltaic, require a power electronic converter between the energy source and the load or the grid. Work presented in this thesis concentrates on dc-dc non-isolated converters suitable for high voltage gain applications, like uninterruptible power supply (UPS) and some of sustainable energy sources. A special attention is on reduction of power losses and efficiency improvements in non-isolated dc-dc step-up converters. During literature study many different non-isolated dc-dc step-up topologies were found, however not all of them are desiredfor high voltage gain applications. It’s found that converters based on an inductor and a coupled-inductor principle (a boost and a center tapped boost converters) as well as converters derived from isolated converters (a non-isolated flyback-boost, a non-isolated push-pull-boost and a non-isolated two-inductor-boost converters) are good candidates for future investigation. Analysis and comparison of selected, most promising topologies indicated that a non-isolated push-pull-boost and a non-isolated two-inductor-boost converters are the best candidates for applications requiring a high voltage gain. Design of a high efficiency converter requires a detailed knowledge and accurate prediction of power losses. For this purpose average steady-state models of selected topologies and component loss models are developed and implemented in MATLAB. Converter models base on analysis of ideal waveforms and are built-up from set of equations describing values essential for power loss calculation, e.g. average or rms current values. These data are used by component models to calculate losses in particular components. It’s important that component models use parameters from datasheets in most cases. It enables performance comparison of different topologies as well as comparison of different components. The proposed modeling approach was verified using a basic boost converter breadboard. With small modification these models may be used for design purposes, like search for optimum output power and optimum switching frequency for given topology and given MOSFETs. Using developed tools and models the converter breadboard was designed. The breadboard demonstrated a very high efficiency, comparable with present state-of-the-art isolated converters. A modular converter concept and its influence on a fuel cell converter overall efficiency were investigated too. Based on simulation and measurement results it was demonstrated that the parallel modular converter used in a fuel cell application achieves a high efficiency over wide range of the output power. Moreover, the efficiency increases while the output power decreases, which is opposite to a solid converter solution.
This translates into a higher efficiency due to reduced switching and conduction ... The three-level do-dc buckconverter is shown in Fig.I As can ... is shown in ' fable I. The different modes refer to: I- zero phase- shift (^): 2- ... where : Al is the peak-to-peak ripple of the inductor Current. ... where: i is the full load output current.
In this paper we propose a sliding mode control scheme that allows robust control of the output voltage in a class of nonlinear switched converters that includes the Non-Inverting Buck-Boost, the Watkins-Johnson and the Inverse of Watkins-Johnson. Using a full-state reference profile-based sliding s...
Neural networks are scarcely applied to power electronics. This attempt includes two different topics: optimal control and computerized simulation. The learning has been performed through output error feedback. For implementation, a buckconverter has been used as a voltage pulse generator. (D.L.) 7 refs.
The unavoidable nonidealities with switching delay in current-mode-controlled buckconverters have been reported in the literature. Investigations are carried out on the dynamical mechanism and its experimental validation on an interrupted circuit with switching delay. Switching delay is seen to influence a region of a two-valued function on a discrete map, and to induce the coexistence of a periodic orbit.
We show the main results obtained when applying the average theory to Zero Average Dynamic control technique in a buck power converter with pulse-width modulation (PWM). In particular, we have obtained the bound values for output error and sliding surface. The PWM with centered and lateral pulse con...
This paper presents an analysis on the effect of having different number of capacitors n in the first-stage switched-capacitor circuit of an improved hybrid switched-capacitor buckconverter for high-voltage-gain conversion. Various aspects of the topology, operation, and efficiency are investigated...
This paper presents an analysis on the effect of having different number of capacitors n in the first-stage switched-capacitor circuit of an improved hybrid switched-capacitor buckconverter for high-voltage-gain conversion. Various aspects of the topology, operation, and efficiency are investigated...
The control proposed and analyzed in this paper is based on the peak current mode control of the output capacitor current of a Buckconverter. The output capacitor current loop provides fast dynamic response to the control since it behaves as a feed-forward of the load current while the voltage loop...
In order to deliver near-field electromagnetic power to a biomedical device or an RFID tag efficiently, the downlink signal is preferred to be at a high voltage level. To reduce power consumption and meet low supply requirements, it is advantageous for the remote device power supply to step-down the input voltage following rectification, typically using switch-mode regulators. The output ripple of a switched capacitor converter is inversely proportional to the filtering capacitance at the output node and switching frequency. In this paper, a hybrid DC?DCconverter utilizing a switched capacitor regulator in master?slave configuration with a linear regulator is presented. Linear regulator actively cancels the switching ripple, while low frequency and DC current is provided by the switched c...
This paper describes the dynamics modelling of a practical and cost-effective DC/DCconverter, DC/AC inverter and AC/DC rectifier for an uninterruptible power supply (UPS) system with backup proton exchange membrane fuel cell (PEMFC) and battery. Furthermore, a dynamics modelling and intelligent comprehensive controller for the PEMFC is designed according to the change of the load, while the energy storage elements, such as battery and supercapacitor, are chosen to compensate the slow dynamic response of PEMFC and to meet the sudden peak load energy demand. The power converters based on dynamic modelling and controllers designed by feedback control theory can supply high quality power with flexible conversion functions, leading to the establishment of reliable power management for UPS appl...
Fuzzy logic or fuzzy set theory is recently getting increasing emphasis in process control applications. The paper describes an application of fuzzy logic in speed control system that uses a dc-dcconverter. The fuzzy control is used to linearize the family of external characteristics of the converter in discontinuous-conduction mode occurring at light load and/or high speed. In order to compare the conventional control with the fuzzy logic control, algorithms have been developed in detail and verified by Microsoft Excel simulation. The simulation study indicates that fuzzy control is a good alternative for conventional control methods, being used particularly in non-linear complex systems ill defined or totally unknown. Where the mathematical model exists, it is useful. The applications of fuzzy set theory in power electronics are almost entirely new; fuzzy logic seems to have a lot of premises in the large industrial control field. (orig.) 2 refs.
This paper proposes a high performance single-stage inverter topology for the autonomous operation of a solar photovoltaic system. The proposed configuration which can boost the low voltage of photovoltaic (PV) array, can also convert the solar dc power into high quality ac power for driving autonomous loads without any filter. An MPPT circuit with parallel connection is implemented so that the part of the energy generated is processed by the dc-dcconverter to supply dc loads. The line current total harmonic distortion (THD) obtained using this configuration is quite reasonable. The proposed topology has several desirable features such as low cost and compact size as number of switches used, are limited to four as against six switches used in classical two-stage inverters. In this paper analysis, simulation and experimental results are presented. (author)
This paper proposes a high performance single-stage inverter topology for the autonomous operation of a solar photovoltaic system. The proposed configuration which can boost the low voltage of photovoltaic (PV) array, can also convert the solar dc power into high quality ac power for driving autonomous loads without any filter. An MPPT circuit with parallel connection is implemented so that the part of the energy generated is processed by the dc-dcconverter to supply dc loads. The line current total harmonic distortion (THD) obtained using this configuration is quite reasonable. The proposed topology has several desirable features such as low cost and compact size as number of switches used, are limited to four as against six switches used in classical two-stage inverters. In this paper a...
Power generation with the help of Photovoltaic (PV) arrays is emphasized increasingly and regarded as an important resource of power energy in the coming years. As the power supplied by PV arrays depends upon the insolation, temperature and array voltage, it is necessary to control the operating point to extract the maximum power from the PV arrays. A number of methods for Maximum Power Point Tracking (MPPT) has been reported in the literature. This paper discusses an adaptive method as well as compares with the conventional fixed step size method, effectively improves the MPPT speed and accuracy simultaneously. An adaptive algorithm and two phase dc-dcConverter is exercised as a MPP tracker. Ripple reduction is possible at input and output side of the converter. Mathematical models of co...
The concept of passive hybrid, i.e. the direct electrical coupling between a fuel cell system and a battery without using a power converter, is presented as a feasible solution for powertrain applications. As there are no DC/DCconverters, the passive hybrid is a cheap and simple solution and the power losses in the electronic hardware are eliminated. In such a powertrain topology where the two devices always have the same voltage, the active power sharing between the two energy sources can not be done in the conventional way. As an alternative, control of the fuel cell power by adjusting its operating pressure is elaborated. Only pure H2/O2 fuel cell systems are considered in this approach. Simulation and hardware in the loop (HIL) results for the powertrain show that this hybrid power so...
A petrol driven moped is converted to an electric one by replacing the petrol engine by a three phase 1.5 HR, AC squirrel cage induction motor drive system. The motor voltage rating selected is 200 V to keep the DC boost voltage level to a reasonable value.f the power source used is a high energy density, 24 V, 110 Ah, Ni-Zn battery. A modified indirect current controlled step-up chopper as well as a standard push-pull DC-DC boost converter is studied for the boost scheme. A simple three phase quasi-square wave inverter is designed along with suitable protection for driving the motor. Successful trial test of the system has been conducted at the laboratory.
Abstract A new single-stage-isolated ac-dc converter that can guarantee both high efficiency and high power factor is proposed. It is based on a new dc-dc topology that has prominent conversion ratio similar to that of boost topology so that it is adequate to deal with the universal ac input. In addition, since it utilizes the transformer more than others based on the general flyback topology, the size of whole power system can be reduced due to the reduced transformer. Moreover, the voltage stresses on the secondary rectifiers can be clamped to the output voltage by adopting the capacitive output filter and clamp diode, and the turn-off loss in the main switch can be reduced by utilizing the resonance. Furthermore, since this converter operates at the boundary conduction mode, the line in...
Developmental progress of the residential solar-powered air conditioner systems was reported. For the uni-directional system with no regeneration of surplus power, the DC/DCconverter was adopted which can optimize a PV array voltage and boost it up to the DC voltage of inverter type air conditioners. As its performance was tested in a model house, nearly 51% of air conditioner power could be supplied in the summer by comparatively small-capacity PV array of 600 W. For the bi-directional system with regeneration, the full-bridge converter and band pass filter for a control loop were adopted to improve transient response characteristics at rapid change in air conditioner load or service interruption. As the effect of the uni-directional system was estimated under the assumption of its installation in all residences in Japan, it could bear nearly 10% of peak power in the summer and reduce CO2 by nearly 0.9% yearly. 7 refs., 15 figs., 1 tab.
This paper presents an adaptive fuzzy-proportional integral derivative (PID) controller for DC-DC boost converters used as voltage regulators in PV systems. This proposed controller maximizes the stable operating range by tuning the PID parameters ultimately at various loading conditions. Then, a fuzzy logic approach is used to add a factor of intelligence to the controller such that it can move among different values of proportional gain (Kp), integral gain (Ki) and derivative gain (Kd) based on the system conditions. This controller allows optimal control of boost converters at any loading condition with no need to retune parameters or possibility of failure. Moreover, the paper presents a novel technique to move between the PI and PID configurations of the controller such that the minim...
Single-phase stand-alone PV system is suitable for household applications in remote area. Hybrid battery/ultra-capacitor energy storage can reduce charge and discharge cycles and avoid deep discharges of battery. This paper proposes a compact seven switches structure for stand-alone PV system, which otherwise needs nine switches configuration, inclusive of one switch for boost converter, four switches for single-phase inverter and four switches for two DC/DCconverters of battery and ultra-capacitor. It is well-known that a bulky DC-link capacitor is always required to absorb second-order harmonic current caused by single-phase inverter. In the proposed compact topology, a small size DC-link capacitor can achieve the same function through charging/discharging control of ultra-capacitor to mitigate second-order ripple current. Simulation results are provided to validate the effectiveness of the topology and control schemes of the proposed system.
A design method using quantitative feedback theory (QFT) for robust control of PWM DC-DCconverters is developed. Parametric and nonparametric uncertainty can be described accurately with this technique. Besides, with the proposed method, the controller can consider both continuous and discontinuous conduction mode models (CCM and DCM respectively). Considering these sources of uncertainty results in a robust controller insensitive to parametric variations and also to different plant cases due to different conduction modes. A power converter satisfying a well-known industry standard is presented as a design example, in order to demonstrate that, with the proposed procedure, the performance of the regulated system can be tightly specified not only in terms of frequency requirements, but als...
This article describes a battery charger, which is powered by thermoelectric (TE) power modules. This system uses TE devices that directly convert heat energy to electricity to charge a battery. The characteristics of the TE module were tested at different temperatures. A SEPIC dc-dcconverter was applied and controlled by a microcontroller with the maximum power point tracking (MPPT) feature. The proposed system has a maximum charging power of 7.99W: that is better than direct charging by approximately 15%. The objectives are to study the principle of TE power generation and to design and develop a TE battery charger that uses waste heat or another heat source as the direct input power. (author)
Sampled-data analysis and harmonic balance analysis are applied to analyze switching DC-DCconverters under constant on-time control. Design-oriented boundary conditions for the period-doubling bifurcation and the saddle-node bifurcation are derived. The required ramp slope to avoid the bifurcations and the assigned pole locations associated with the ramp are also derived. The derived boundary conditions are more general and accurate than those recently obtained. Those recently obtained boundary conditions become special cases under the general modeling approach presented in this paper. Different analyses give different perspectives on the system dynamics and complement each other. Under the sampled-data analysis, the boundary conditions are expressed in terms of signal slopes and the ramp slope. Under the harmonic balance analysis, the boundary conditions are expressed in terms of signal harmonics. The derived boundary conditions are useful for a designer to design a converter to avoid the occurrence of the ...
In this paper, a simple control strategy for an optimal extraction of output power from grid connected variable speed wind energy conversion system (WECS) is presented. The system consists of a variable speed wind turbine coupled to a permanent magnet synchronous generator (PMSG) through a gear box, a diode bridge rectifier, a dc-to-dc boost converter and a current controlled voltage source inverter. The maximum power point tracker (MPPT) extracts maximum power from the wind turbine from cut-in to rated wind velocity by sensing only dc link power. The MPPT step and search algorithm in addition to the DC-DC and DC-AC converters PWM controllers are simulated using MATLAB-SIMULINK software. The obtained simulation results show that the objectives of extracting maximum power from the wind and ...
A Phase-Locked Loop (PLL)-based frequency synthesizer (FS) with adjustable duty cycle is presented. By employing digital processing circuitry and the ??? fractional-N technique, the FS is capable of generating arbitrary frequencies in a wide frequency range, and capable of adjusting the clock duty cycles. In addition, the switching between different frequencies is instant except when a very fine frequency resolution is required. The adjustable duty cycle and instant switching are desired features in applications such as time-interleaved Analog-to-Digital-Converters (ADCs), switched-capacitor circuits, and DC?DCconverters. The design was fabricated using a 0.13??m CMOS process. This paper gives the theories, analysis, implementation, and measurement results of this FS.
This work presents a study of a half-bridge dc-dcconverter using asymmetrical command on switches with dual thyristor characteristics. This topology can be derived from the conventional half-bridge converter, by allowing the switches to conduct during complementary time intervals in each period of operation. In this way, soft communication is achieved without a remarkable increase in conduction losses. Besides that, one can enlarge the load range in which soft communication is maintained by using a resonant pole. A design procedure is emphasized, in which the transitions of the resonant inductor, is done after a study of minimization of primary efficient current, thus achieving less conduction losses. Experimental results from a 576 W-10 A prototype are shown. (author) 9 refs., 16 figs.
Buck-boost operation of inverters is required for inverter-based PV systems in distributed grid-connected applications when variable resources can create large variations in the input voltage to inverters above and below the output AC voltage. This paper presented a general structure of a grid-connected PV system along with step-down and step-up operation of inverters. It also presented a newly developed, innovative single-phase, single-stage, flyback-based, buck-boost inverter for renewable energy conversion systems, especially for photovoltaic (PV) systems in both grid-connected and standalone applications. It focused on the analysis of the working principles, computer simulation of the operation, and design consideration of the inverter for grid-connected applications. The proposed buck-boost inverter has 4 switching devices. Three operation modes describe the operating principles of this buck-boost inverter. They are the charge mode, the positive half cycle (PHC) discharge mode, and the negative half cycle (NHC) discharge mode. It was concluded that the simple circuit topology of this inverter provides the possibility for a low cost and high efficiency dc-ac converter. The inverters have a low component count with only 3 power semiconductor switches to accomplish dc-ac conversion with a high output power quality. The inverter can accommodate a wide range of input dc voltage for better energy output from variable PV resources. The inverter separates the input source from the output grid through a flyback operation. Both the cost and size of the newly proposed inverter are lower than traditional buck inverters with line-frequency transformers, two-stage buck-boost inverters, and previous single-stage buck-boost inverters. The newly proposed inverted is therefore a more reliable and economical design for PV systems. The analysis of the working principles, and computer simulation of the operation for this inverter have proved its feasibility for dc-ac conversion in PV applications. However, the implementation and tests of the inverter are yet to be done. 4 refs., 1 tab., 22 figs.
In this paper, a non-isolated DC/DCconverter with high voltage ratio is proposed to allow the interface between a low voltage power source like fuel cell and a high voltage DC bus. To take into account the low voltage-high density characteristics of power sources, a cascaded structure composed of two sub-converters has been chosen and allows obtaining a high voltage ratio. The choice of each sub-converter is based on the requirements of the source and its performances. Consequently, we have chosen a three-interleaved boost converter as the 1st sub-converter whereas the 2nd sub-converter is a three-level boost converter. The control of the whole system is realized thanks to energetic trajectories planning based on flatness properties of the system. The control of both the current and the balance of voltage across the output serial capacitors of the three-level boost converter is ensured by non-linear controllers based on a new non-linear model. Experimental results allow validating the proposed power architecture and its associated control. (author)
The low temperature operation of a 48 W, 50 kHz, 36/12 V pulse width modulated (PWM) buck de-de power converter designed with standard commercially available components and devices is reported. The efficiency of the converter increased from 85.6% at room temperature (300 K) to 92.0% at liquid nitrogen temperature (77 K). The variation of power MOSFET, diode rectifier, and output filter inductor loss with temperature is discussed. Relevant current, voltage. and power waveforms are also included.
In this paper, a new two-input isolated boost dc-dcconverter based on a distributed multi-transformer structure which is suitable for hybrid renewable energy systems is investigated and designed. With a novel transformer winding-connecting strategy, the two input ports can be decoupled completely, so the proposed converter can draw the power from the two different dc sources, which have low output voltage, and transfer it to the dc bus, which has high voltage, separately or simultaneously. The detailed operation principles of the proposed converter have been analyzed in the dual-input mode and the single-input mode, respectively. The main advantage of the proposed topology is that the four transformers and the secondary rectifiers are fully utilized whether the converter is connected with two input power sources or only one input. Although the four transformers are employed, the nominal powers of each transformer and rectifier are both reduced by four times. Furthermore, some special issues on converter design, such as increasing number of the input ports, the magnetic integration and the ground loop decoupling are discussed. A 2 kW prototype was built and tested. Experiments on the converter’s steady-state and transient operations verified the validity of the analysis and design.
High power isolated DC/DCconverters have been extensively used in various applications. Significant research efforts have been devoted to increase the operating efficiency and power density of the converter. Soft switching full bridge converter has been proposed to meet these goals by establishing zero voltage switching condition across the power transistors. However, a significant inductor is required to facilitate the resonance condition, and results in increased loss and reduced power density of the converter. In this article, a full bridge converter with limited soft switching capability (1)-(3) and a coaxially-wound transformer are presented to improve the power density. With the coaxial winding structure, the coupling coefficient the transformer will be much higher than conventional transformer, and result in small leakage inductance. The duty cycle loss of the converter is also reduced thanks to the low leakage inductance of the coaxial transformer. Various coaxial structures are presented in this paper Detailed simulations using Ansoft are conducted to observe their magnetic characteristics. These coaxial transformers are constructed in the laboratory and tested with the full bridge converter under soft-switching conditions to evaluate the performance of the entire system.
A soft switching method with small switching loss was proposed for the purpose of increasing the efficiency of a DC-DC boost converter which converted a DC current generated by solar cells to a variable DC current. Existing current converters are supplemented by using a snubber circuit around the switch so as to protect the switch by a hard switching action. However, with an increase of the output current, snubber loss is increased, reducing the efficiency. In order to solve this problem, the partial resonant switch method was applied to the converter; with this method of partially forming a resonant circuit only at the time of turning on/off of the switch, the switching loss was reduced through the soft switching, thereby making the proposed converter operate with high efficiency. Moreover, the resonant element of the partial resonant circuit using a snubber condenser, the energy accumulated in the condenser was regenerated on the power supply side without loss of snubber. With the regenerated energy, the proposed converter was provided with a smaller ratio of switching to use than the conventional converter. 4 refs., 7 figs., 1 tab.
Eight In(AI)GaAs PN junctions grown epitaxially on the semi-insulating wafer were monolithically integrated in series to boost the approximately 0.4V photovoltage per typical In(Al)GaAs junction to over 3 volts for the 1 sq cm laser power converted (LPC) chip. Advantages of multijunction LCP designs include the need for less circuitry for power reconditioning and the potential for lower I(sup 2)R power loss. As an example, these LPC's have a responsivity of approximately 1 amp/watt. With a single junction LPC, 100 watts/sq cm incident power would lead to about 100 A/sq cm short-circuit current at approximately 0.4V open-cicuit voltage. One disadvantage is the large current would lead to a large I(sup 2)R loss which would lower the fill factor so that 40 watts/sq cm output would not be obtained. Another is that few circuits are designed to work at 0.4 volts, so DC-DC power conversion circuitry would be necessary to raise the voltage to a reasonable level. The multijunction LPC being developed in this program is a step toward solving these problems. In the above example, an eight-junction LPC would have eight times the voltage, approximately 3V, so that DC-DC power conversion may not be needed in many instances. In addition, the multijunction LPC would have 1/8 the current of a single-junction LPC, for only 1/64 the I(sup 2)R loss if the series resistance is the same. Working monolithic multijunction laser power converters (LPC's) were made in two different compositions of the In(x)Al(y)Ga(1-x-y)As semiconductor alloy, In(0.53)Ga(0.47)As (0.74 eV) and In(0.5)Al(0.1)Ga(0.4)As (0.87 eV). The final 0.8 sq cm LPC's had output voltages of about 3 volts and output currents up to about one-half amp. Maximum 1.3 micron power conversion efficiencies were approximately 22 percent. One key advantage of multijunction LPC's is that they have higher output voltages, so that less DC-DC power conversion circuitry is needed in applications.
The concept of a passive hybrid system consisting of fuel cell stacks, Li-ion battery packs, and two diodes was tested. The diodes take the place of the DC/DCconverter that is usually used to align fuel cell and battery voltages, thereby directly connecting the fuel cell and the battery. Prototype equipment was built for collecting characteristic data on the static and dynamic behavior of the hybrid system. The measurement results indicate that increasing the operation efficiency and simplifying the system were possible by applying the direct hybridization concept. The dynamic behavior results showed an interesting combination of output signals from the fuel cell stack and the battery pack. The quick response of the battery output completely compensated for the delay in fuel cell output r...
Necessitated by the dwindling supply of petroleum resources, various new automotive technologies have been actively developed from the perspective of achieving energy security and diversifying energy sources. Hybrid electric vehicles and electric vehicles are a few such examples. Such diversification requires the use of power control units essentially for power control, power conversion and power conditioning applications such as variable speed motor drives (dc-ac conversion), dc-dcconverters and other similar devices. Power control unit of a hybrid electric vehicle or electric vehicle is essentially the brain of the hybrid system as it manages the power flow between the electric motor generator, battery and gas engine. Over the last few years, the performance of this power control unit h...
This paper presents a model of a hybrid electric vehicle, based on a primary proton exchange membrane fuel cell (PEMFC) and an auxiliary Li-ion battery, and its dynamics and overall performance. The power voltage from the fuel cell is regulated by a DC/DCconverter before integrating with the Li-ion battery, which provides energy to the drive motor. The driving force for propelling the wheels comes from a permanent magnet synchronous motor (PMSM); where the power passes through the transmission, shaft, and the differential. The mathematical model, comprising the PEMFC, Li-ion battery, PMSM, and vehicular structure, was modeled in MATLAB/Simulink. A power management model was incorporated in the system such that the power output varies in different conditions; including high power, low powe...
A new closed-loop generalised scheme for an n-stage current-mode multiphase switched-capacitor converter (CMSC) is proposed by combining multiphase operation and pulse-width-modulation (PWM) control for step-up DC-DC conversion and output current regulation. The CMSC is composed of n-voltage doublers and one constant current source in series. The n-voltage doublers are in charge of boosting output voltage, and combined with multiphase operation to provide voltage gain of 2n at most. The current source is adopted mainly for supplying a constant current at the output terminal, and combined with PWM to reinforce output regulation as well as robustness to source/loading variation. The relevant theoretical analysis and design include: an n-stage CMSC model, steady-state/dynamic analysis, power ...
An on-chip charge pump (CP) DC-DCconverter applicable to potable displays is described. A merged 2x/3x booster eligible for both single-phase pumping and dual-phase pumping is developed. A closed-loop sensing scheme with analog/digital mixed-mode voltage regulation helps to ensure a low ripple output voltage and high power transfer efficiency. A test vehicle was implemented for a DC input range of 2.2-3.6V and the DC output of 5V with a load condition of 20mA in a standard 0.35-mm 2poly-4metal CMOS process. The test results reveal output ripple of less than 80mV and efficiency of 77.4% in the 2x dual phase mode.
Sensing and controlling current flow is a fundamental requirement for many electronic systems, including power management (DC?DCconverters and LDOs), battery chargers, electric vehicles, solenoid positioning, motor control, and power monitoring. Current shunt monitor (CSM) system enables current measurement across an external sense resistor (R S ) in series to current flow. Proposed CSM system can sense a system (power supply) current from 1 to 500 mA across a typical board Cu-trace resistance of 1 ? with less than 10 ?V input-referred offset, 150 nV/°C offset drift and 0.1% accuracy. Instead of using a costly zero-TC sense resistor (R S ) that is used in typical CSM systems; proposed method uses existing Cu board trace for sensing. The sense amplifier uses chopper stabilization in the si...
This thesis concerns an innovative photovoltaic system concept, which is modular am where the standardisation of all of the components is possible. Lead-acid batteries tare used to store the energy. The main objective of this project is the improvement of the battery management process in the system. As the batteries are the weak point of the system, a new battery charger is developed aiming at a longer life-span and a homogeneous ageing rate for all of them. This charger permits energy exchanges, which are co-ordinated by a communication system. We use a DC/DCconverter as power electronics for battery charging. PSpice simulations and tests verify its performance. Simulations with Matlab Simulink show the auto-equalization tendency of the chosen battery management method. In addition, an experimentation under real conditions validates the beneficial effect on the state of health of the batteries. (author)
This paper presents a generic approach for PV panel modeling. Data for this modeling can be easily obtained from manufacturer datasheet, which provides a convenient way for the researchers and engineers to investigate the PV integration issues. A two-stage power conversion system (PCS) is adopted in this paper for the PV generation system and a Battery Energy Storage System (BESS) can be connected to the dc-link through a bi-directional dc/dcconverter. In this way, the BESS can provide some ancillary services which may be required in the high penetration PV generation scenario. In this paper, the fault ride-through (FRT) capability is specifically focused. The integrated BESS and PV generation system together with the associated control systems is modeled in PSCAD and Matlab platforms and the effectiveness of the controller is validated by the simulation results.
A light electric vehicle (LEV) equipped a hybrid power system has been developed in the present work. The hybrid power system consisted of a proton exchange membrane (PEM) fuel cell and a lithium-ion battery. The former serves the major propulsion power, while the later takes some of the peak power requirement as well as allows regenerative braking. First, major components of the hybrid power system such as a fuel cell stack, a membrane humidifier, a lithium-ion battery pack, a microcontroller, a DC/DCconverter, and hydrogen storage canisters (HSCs) are developed and verified. Special attention will be placed on the implementation of the stack-humidifier assembly and the hydrogen storage canister. Then, a breadboard test to assess the efficiency of the hybrid power system is provided. Sub...
In this work, we show that chaos control techniques can be used to increase the region that can be efficiently used to supply the power requests for an artificial satellite. The core of a satellite power subsystem relies on its DC/DCconverter. This is a very nonlinear system that presents a multitude of phenomena ranging from bifurcations, quasi-periodicity, chaos, coexistence of attractors, among others. The traditional power subsystem design techniques try to avoid these nonlinear phenomena so that it is possible to use linear system theory in small regions about the equilibrium points. Here, we show that chaos control can be used to efficiently extend the applicability region of the satellite power subsystem when it operates in regions of high nonlinearity.
Sensing and controlling current flow is a fundamental requirement for many electronic systems, including power management (DC?DCconverters and LDOs), battery chargers, electric vehicles, solenoid positioning, motor control, and power monitoring. Current shunt monitor (CSM) system enables current measurement across an external sense resistor (R S ) in series to current flow. Proposed CSM system can sense a system (power supply) current from 1 to 500?mA across a typical board Cu-trace resistance of 1?? with less than 10??V input-referred offset, 150?nV/?C offset drift and 0.1% accuracy. Instead of using a costly zero-TC sense resistor (R S ) that is used in typical CSM systems; proposed method uses existing Cu board trace for sensing. The sense amplifier uses chopper stabilization in the si...
The purpose of this Letter is to show how a border-collision bifurcation in a piecewise-smooth dynamical system can produce a direct transition from a stable equilibrium point to a two-dimensional invariant torus. Considering a system of nonautonomous differential equations describing the behavior of a power electronic DC/DCconverter, we first determine the chart of dynamical modes and show that there is a region of parameter space in which the system has a single stable equilibrium point. Under variation of the parameters, this equilibrium may collide with a discontinuity boundary between two smooth regions in phase space. When this happens, one can observe a number of different bifurcation scenarios. One scenario is the continuous transformation of the stable equilibrium into a stable period-1 cycle. Another is the transformation of the stable equilibrium into an unstable period-1 cycle with complex conjugate multipliers, and the associated formation of a two-dimensional (ergodic or resonant) torus.
The purpose of this book is to assemble, in one place, the comprehensive tools necessary to meet the growing demands placed upon solid-state power conversion equipment. Aspects of transient analysis, circuit analysis, and waveforms are discussed, taking into account waveform relations, magnetic fields, dielectric fields, the RL circuit, the RC circuit, the RLC circuit, the RLCR circuit with a DC input, AC circuit analysis, and components scaling. Semiconductors and resistors are considered along with capacitors, transformers, inductors, conductors, rectifiers and filters, phase-control circuits, transistor inverters, thyristor inverters, switching regulators, DC-DCconverters, protection and safety, electromagnetic compatibility and grounding, semiconductor and equipment cooling, reliability and quality, regulated power supplies, and uninterruptible power systems. Attention is given to magnetic materials, toroid tape core transformers, permalloy powder cores, a six-phase dual bridge, thermal conduction and resistance, heat pipes, and thermoelectric coolers.
A high-power power supply produces a controllable, constant high voltage put under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dcconverter modules.
A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dcconverter modules.
A new single phase power factor correction rectifier/regulator with dc linked energy feedback circuit is proposed, which is capable of achieving the zero voltage switching (ZVS) of a boost rectifier stage without any auxiliary switch. The proposed rectifier/regulator gives the good power factor correction (PFC), low current harmonic distortion, and tight output voltage regulation. Moreover, with the proposed scheme, a low cost, high efficiency, and high power density single phase rectifier/regulator can be designed, which is superior to that of a conventional PFC ZVS boost rectifier followed by a ZVS half-bridge dc-dcconverter. The operation of the proposed rectifier/regulator is thoroughly analyzed. Also the control strategy and implementation are provided in details. The performance of the proposed rectifier/regulator is demonstrated through a 200W, 90 kHz prototype. This proposed rectifier/regulator with dc linked energy feedback circuit is particularly suited for distributed power system applications. (author). 13 refs., 15 figs., 1 tab.
This paper presents a control for a three phase five-level neutral clamped inverter (NPC) for grid connected PV system. The maximum power point tracking (MPPT) is capable of extracting maximum power from the PV array connected to each DC link voltage level. The MPPT algorithm is solved by fuzzy logic controller. The fuzzy MPPT is integrated with the inverter so that a DC-DCconverter is not needed and the output shows accurate and fast response. A digital PI current control algorithm is used to remain the current injected into the grid sinusoidal and to achieve high dynamic performance with low total harmonic distortion (THD). The validity of the system is verified through MATLAB/Simulink and the results are compared with three phase three-level grid connected NPC inverter in terms of THD.
The main objective of the EC funded HEATRECAR project is to reduce the energy consumption and curb CO2 emissions of vehicles by massively harvesting electrical energy from the exhaust system and re-use this energy to supply electrical components within the vehicle or to feed the power train of hybrid electrical vehicles. HEATRECAR is targeting light duty trucks and focuses on the development and the optimization of a Thermo Electric Generator (TEG) including heat exchanger, thermoelectric modules and DC/DCconverter. The main objective of the project is to design, optimize and produce a prototype system to be tested on a 2.3l diesel truck. The base case is a Thermo Electric Generator (TEG) producing 1 KWel at 130 km/h. We present the system design and estimated output power from benchmark Bi2Te3 modules. We discuss key drivers for the optimization of the thermal-to-electric efficiency, such as materials, thermo-mechanical aspects and integration.
Abstract Since the mechanical power extracted from wind is proportional to the cube of the wind speed, the output of the wind turbine generator system fluctuates considerably due to wind speed variations. Therefore, high penetration of wind power to the power grid causes fluctuation of the grid frequency, which has adverse effects on power system stability and reliability. Since a superconducting magnetic energy storage (SMES) system has the ability to provide both active and reactive power simultaneously and quickly, the SMES system can be an effective tool to mitigate frequency fluctuations under such conditions. In the present study, a PWM voltage source converter and two-quadrant DC-DC-chopper-controlled SMES system is proposed, which can significantly decrease the voltage and output p...
This dissertation proposes a new dc-dcconverter to provide two independently regulated dc outputs from a single dc voltage source using one power semiconductor switch. The operation is based upon the use of a low pass filter and a higher frequency band pass filter. The output voltage supplied from the low pass filter is regulated by controlling the duty cycle of the switch, while the other output voltage is controlled by changing the switching frequency. The state space averaged model is used to predict the circuit behavior. In addition, computer simulation is employed to confirm the theoretical results. Finally, an experimental model is constructed and implemented using an Intel 8096 microcontroller to demonstrate the actual circuit performance and to confirm the theoretical and simulation results.
The Electronic Systems Engineering Department of the Computing Division at the Fermi National Accelerator Laboratory is carrying out R&D investigations for the upgrade of the power distribution system of the Compact Muon Solenoid (CMS) Pixel Tracker at the Large Hadron Collider (LHC). Among the goals of this effort is that of analyzing the feasibility of alternative powering schemes for the forward tracker, including DC to DC voltage conversion techniques using commercially available and custom switching regulator circuits. Tests of these approaches are performed using the PSI46 pixel readout chip currently in use at the CMS Tracker. Performance measures of the detector electronics will include pixel noise and threshold dispersion results. Issues related to susceptibility to switching noise will be studied and presented. In this paper, we describe the current power distribution network of the CMS Tracker, study the implications of the proposed upgrade with DC-DCconverters powering scheme and perform noise susceptibility analysis.
The Electronic Systems Engineering Department of the Computing Division at the Fermi National Accelerator Laboratory is carrying out R&D investigations for the upgrade of the power distribution system of the Compact Muon Solenoid (CMS) Pixel Tracker at the Large Hadron Collider (LHC). Among the goals of this effort is that of analyzing the feasibility of alternative powering schemes for the forward tracker, including DC to DC voltage conversion techniques using commercially available and custom switching regulator circuits. Tests of these approaches are performed using the PSI46 pixel readout chip currently in use at the CMS Tracker. Performance measures of the detector electronics will include pixel noise and threshold dispersion results. Issues related to susceptibility to switching noise will be studied and presented. In this paper, we describe the current power distribution network of the CMS Tracker, study the implications of the proposed upgrade with DC-DCconverters powering scheme and perform noise susceptibility analysis.
A high-energy ignition device is described for an engine, the high energy ignition device comprising: a pickup for generating an output synchronous with operations of the engine; an ignition circuit including a switching device adapted to be turned on and off in accordance with the output from the pickup; an igniter coil including a primary coil connected to the switching device, a secondary coil in which a high voltage is generated in response to an abrupt turning on and off of electric current in the primary coil, and an iron core between the primary and secondary coils; and a DC-DCconverter including a transformer including by a primary coil, a secondary coil and an iron core between the primary and secondary coils, a switching element connected in series to the primary coil, and an oscillator for turning the switching element on and off at a predetermined frequency.
This study presents a symbolic method for the design of filter capacitors in DC?DC switching converters, using a combination of a ceramic and an electrolytic capacitor. Assuming that the overall capacitor is subject to a square wave-like current, and modelling each of the two parallel capacitors as the series of a capacitance C and a resistance R, analytical formulas are derived to express the ripple voltage on the capacitors and each of the two rms currents as a function of the capacitor parameters. For each fixed ceramic capacitor, an acceptability region for the electrolytic one can be drawn in the C?R electrolytic plane to represent the available set of capacitors, separating those feasible (complying with the design constraints, such as those on the ripple and rated voltage and on the...
In this study, a small portable fuel cell/battery hybrid system has been developed. The system consists of a single portable direct borohydride/peroxide fuel cell (DBPFC), NiMH battery and power management unit (PMU). The battery has been used as a primary power source and has been discharged at constant load. When its state of charge is reduced, the DBPFC charges the battery and powers the load simultaneously. A DC-DC Boost converter has been used as a PMU. The DBPFC has provided the total power of 0.21Wh into the system during the charge. During this experimental study fuel (NaBH"4) efficiency of 37% has been achieved in the hybrid system, while the system efficiency has been calculated as 34.5%.
Switch mode audio power amplifiers are showing up on market in still greater numbers because of advantages in form of high efficiency and low total system cost, especially for high power amplifiers. Several different modulator topologies have been made, ranging from standard PWM to various self oscillating and digital modulators. Performance in terms of low distortion, noise and dynamit range diffen significantly with the modulator topology ured. Highest system performance is generally achleved with analog modulators made as a modulator loop including at least the power stage of the amplifier, because of benefits from continuous time operation and mon-quantized resolution. This type of modulator uses no external carrier signal, and is called self oscillating modulators. The work presented in this paper refers to switch mode audio amplifier, but eau be used within a wide range of DC-DC or DC-AC converters as well. (au)
This paper presents a hybrid electric power system for a real surface tramway. The hybrid system consists of two electrical energy sources integrating a single dc/dcconverter to provide the power demanded by the tramway loads (four electric traction motors and auxiliary services): (1) a Polymer Electrolyte Membrane (PEM) fuel cell (FC) as the primary and (2) a rechargeable Ni-MH battery as electrical energy storage to supplement the FC over the driving cycle. According to the requirements of the real driving cycle of the tramway, it was considered a 200kW PEM FC system with two FCs connected in parallel and a 34 Ah Ni-MH battery. The PEM FC and Ni-MH battery models were designed from commercially available components. The power conditioning system provides the appropriate power for the tr...
Fuel cell power systems have increasingly become popular because of their inherent advantages over conventional energy systems. A fuel cell system typically requires some kind of power conditioning that usually includes a DC-DCconverter and a DC-AC inverter. In a single phase system, the operation of a single phase inverter introduces a second harmonic (120 Hz) current ripple into the system. This ripple has been found to be detrimental to the performance, life and efficiency of the fuel cell if it is not adequately controlled. This paper proposes an active filtering method to cancel the second harmonic current ripple drawn from the fuel cell source in a single phase fuel cell system. This approach provides an alternate path for the 120 Hz current preventing it from flowing through the fu...
Superconducting transmission line magnet test system for an injector accelerator of a staged VLHC proton-proton colliding beam accelerator has been built and operated at Fermilab. The 1.5 m long, twin-aperture, combined function dipole magnet of 2 Tesla field is excited by a single turn 100 kA transmission line superconductor. The 100 kA dc current is generated using dc-dc switching converters powered by a bulk 240 kW supply. A pair of horizontally placed conventional leads facilitates transfer of this current to the magnet transmission line superconductor operating at liquid helium temperature. Fabrication of magnet components and magnet assembly work are described. The magnet test system and its operation are presented, and the performance is summarized.
A switched capacitor step-down DC-DCconverter (charge pump) is proposed. High efficiency is achieved by combination of fractional conversion ratios (different step-down modes of operation), output voltage sensing and pulse skipping based digital control techniques. Two control techniques were implemented with automatic change between modes and their results are discussed and compared. The power module has 9 switches, implemented with 14 power transistors, and a current limit circuit to mitigate the in-rush current in startup phase. This circuit has been designed in AMS C35B4 (0.35um) CMOS process. The charge pump was designed to provide a maximum load current of 100mA. The peak-to-peak output voltage ripple is less than 30mV with two 3uF flying capacitors and one 20uF output capacitor. Peak and average efficiencies, with maximum load current, are over 80% and 68%, respectively.
A new type of power supply system for a gyrotron with collector potential depression (CPD) to enhance gyrotron efficiency was developed. The power supply system is composed of a main power supply (MPS) and an acceleration power supply (APS). The APS which provides the stable high field to the magnetron injection gun (MIG) of the gyrotron is the key point of the system. The DC-DCconverter technique is applied to the APS and it can output 100 kV of maximum voltage within {+-}0.5% stability and 300 mA of maximum current. The CPD gyrotron operation was successfully achieved with an efficiency of 48% and power of 350 kW for 5 s at 110 GHz. The stable gyrotron operation, without regulation of MPS, which provides the d.c. input power to the gyrotron, has been demonstrated by the combination of the APS and MPS. (orig.)
Described is a system that can provide electrical power to stacks of switching circuits while maintaining exceptional isolation between high voltage planes. High power laser diode bars are used to illuminate highly efficient photovoltaic cells. This is accomplished using efficient and cost-effective lens ducts and optical fiber segments. Such a system can be very efficient in transmitting optical power to the photocell. Using a glass lens duct we can achieve a theoretical isolation of 200 kV using a unit no bigger than a conventional dc-dcconverter with isolation of only 50 kV. The trade off being total electrical efficiency, which is predicted to still be as high as 44 percent.
Due to the severity of the global energy crisis and environmental pollution, the photovoltaic (PV) system has become one kind of important renewable energy source. Solar energy has the advantages of maximum reserve, inexhaustibleness, and is free from geographical restrictions, thus making PV technology a popular research topic. This study is aimed at developing a PV charging system for Li-ion batteries by integrating Maximum Power Point Tracking (MPPT) and charging control for the battery. In order to enable the solar cell to use the sunlight effectively, a DC/DC boost converter for solar power generation was first designed, which used the MPPT Algorithm of Variable Step Size Incremental Conductance Method (INC) to enable the solar cell to track the MPPT at any time. The output from the D...
Due to their higher efficiency and low emissions, fuel cells have distinct advantages over combustion engines for powering motor vehicles. However, to assess the overall efficiency of a fuel cell driven vehicle, all the elements of the chain must be taken into account. Besides the electromechanical conversion, power electronics is required for controlling the power output. In the present article the development of the conversion and charging electronics for a small electrically powered pleasure boat is reported. The system is composed of a fuel cell, a rechargeable battery, the electric motor and the electronics. The attained efficiencies were above 95 % for the battery charger and 93-98 % for the DC-DC-converter. The authors stress the need for optimized electronics in accordance with the electrochemical cells, implying the development of specific electronics for each type of cell.
In this study, a low temperature sintering thickness-vibration-mode multilayer piezoelectric transformer for a DC–DCconverter was manufactured using (Pb0.76Ca0.23Sr0.01)Ti0.96(Mn1?3Sb2?3)0.04O3 ceramics. Its electrical properties were investigated according to the variations in frequency and load resistance. The voltage step-up ratio of the multilayer piezoelectric transformer showed a maximum value at a resonant frequency of 1.444 MHz and increased with an increase in load resistance. The efficiency of the multilayer piezoelectric transformer showed the highest value at a load resistance of 17 ?. The output power increased with increasing input voltage. When the output impedance of the multilayer piezoelectric transformer coincided with the load resistance, output power showed the highest value of 18 W within a 20 °C temperature increase.
DC/DCconverters are widely used in consumer electronic devices where usually a single power source is available while the electronic board of the device requires different voltage levels in order to power-up different block functions. In this paper we present the design of a MEMS single-input multi-output voltage level shifter. The low-voltage to high-voltage conversion is based on the electrostatic transduction of variable capacitors built using interdigitated comb fingers. A 1 mm2 MEMS prototype has been designed and fabricated using the SOIMUMPs process. In this study we present the co-design and co-simulation of the whole system (the MEMS device and its dedicated charge-pump-circuit) in a single EDA environment through MEMS+ (a Coventorware® tool that allows the co-simulation of MEMS ...
This paper presents about an example of circuit design and characteristics of inverter according to the variable capacitance of the DC voltage source separation capacitor used in ZVS-HB type high frequency resonant inverter. The soft switching technology known as ZVS is used to reduce turn off loss at switching. In the event the capacitance of the DC voltage source separation capacitor is varied, the analysis of inverter circuit has generally described by using normalized parameter and operating characteristics have been evaluated in terms of switching frequency and parameters. According to the calculated characteristics value, a method of the circuit designs and operating characteristic of the inverter is also presented in this paper. In addition, this paper proves the validity of theoretical analysis through the experiment. This proposed inverter shows that it can be practically used in future as power source system for the lighting equipment of discharge lamp, DC-DCconverter etc. (author). 6 refs., 10 figs., 2 tabs.
DC/DCconverters are widely used in consumer electronic devices where usually a single power source is available while the electronic board of the device requires different voltage levels in order to power-up different block functions. In this paper we present the design of a MEMS single-input multi-output voltage level shifter. The low-voltage to high-voltage conversion is based on the electrostatic transduction of variable capacitors built using interdigitated comb fingers. A 1?mm2 MEMS prototype has been designed and fabricated using the SOIMUMPs process. In this study we present the co-design and co-simulation of the whole system (the MEMS device and its dedicated charge-pump-circuit) in a single EDA environment through MEMS+ (a Coventorware? tool that allows the co-simulation of MEMS ...
The extended run Uninterruptible Power Supply system (UPSs) which powered by fuel cells and supercapcitors, is a promising solution for future data centre to obtain environmentfriendly energy efficient and cost effective. There are many challenges in power electronic interface circuits, because of the characteristics of these two power sources: long warm-up stage and low dynamics for fuel cell, and variable terminal voltage for supercapacitors. The motivation for this project was to find ways which can overcome those limitations to integrate fuel cells and supercapcitors to the system with high efficiency and high reliability. Therefore, special focus is given to hybrid dc conversion circuits. From an overview of current state-of-the-art, based on the work of others, the thesis will show the methods utilized in this project to combining fuel cells and supercapcitors for the frontend dc system with cascaded structure and direct-couple structure. The challenges and advantages of the solutions proposed will be described. In order to achieve integrality of the system, the research work on three-phase three-level neutral-point-clamped (3LNPC) inverters will be included in the thesis as well. The contributions are: • Optimized design method for dual active bridge (DAB) converter and its derived circuits; • A novel hybrid dc-dcconverter and its corresponding optimal design method are proposed; • An improved dual input current-fed DC-DCconverter with bidirectional power conversion ability is investigated; • Extend the circuit level decoupling modulation scheme into 3LNPC inverter. As to the DAB converter, through the power factor and harmonics analysis, the dominated loss factor is found in variable input voltage range. Optimized parameter choosing method is used to decide the ac inductance and switching frequency. Considering the input impendence of fuel cell and super-cap, the small-signal stability of cascaded converter is analyzed. The system small-signal model is rebuilt and controllers for current loop and voltage loop are designed to obtain good transient performance. Through analysis and synthesis of the traditional cascaded converters, a novel hybrid bidirectional dcdc converter which combines a fuel cell with a boost-type half bridge converter, and supercaps with a DAB converter, is proposed. With phase-shift plus duty cycle, all the switches realize ZVS in a wide range of load variation. Duty cycle control reduces the circulating current due to the wide input voltage range. With particular transformer windings connection strategy, the proposed boost-type dual input bidirectional converter can draw power from two different dc sources with lower voltage and deliver it to the higher voltage DC bus or load individually and simultaneously. The multiinput ports extension method and its limitation are discussed. Through circuit level decoupling, the 3LNPC inverter can be decoupled into two DC-DCconverters in each region, making the controller design much simpler. It is possible to reduce the switching losses and achieve voltage balancing between the capacitors in the DC bus.
Abstract in spanish Un sistema de generación eólica para una aplicación aislada es presentado en este artículo. Una topología de convertidores electrónicos de potencia elevador y reductor conectados en cascada es propuesta para controlar la producción eólica en todo el rango de velocidades del viento. Para el rango de vientos suaves, la estrategia de control permite seguir el máximo coeficiente de potencia de turbina eólica mediante el ajuste de la velocidad de rotación del genera (more) dor. En el rango de vientos fuertes, la regulación de la potencia del sistema se hace igualmente por control de la velocidad de giro del generador. La acción de control es realizada mediante el convertidor DC/DC de potencia el cual modifica su tensión de entrada, cambiando así la tensión en los terminales de la máquina y por consecuencia variando la velocidad de rotación del generador. El sistema propuesto es validado mediante simulación por computador. Los resultados muestran que el sistema de control propuesto actúa de buena manera para su aplicación en sistemas autónomos de generación eólica. Abstract in english A controlled wind generation system for a stand alone application is presented in this paper. A cascaded step-up/step-down power electronic converters topology is proposed to control the wind power system in the whole wind speed range. For the low wind speed range, the control strategy is aimed to follow the wind turbine?s maximal power coefficient by adjusting the generator?s rotational speed. For high wind speeds, the system power regulation is also made by controllin (more) g the generator speed. This control is made by the DC/DC power electronic converter, which modifies its input voltage, changing the machine voltage and consequently varying the generator?s rotor speed. The proposed system is validated by computer simulation. The proposed control system shows a good performance for its application in autonomous wind energy systems.
Digital control of switch-mode power supplies and converters has within the last decade evolved from being an academic subject to an emerging market in the power electronics industry. This development has been pushed mainly by the computer industry that is looking towards digital power management in order to reduce the power consumption of servers and datacenters. The work presented in this thesis includes digital control methods for switch-mode converters implemented in microcontrollers, digital signal controllers and field programmable gate arrays. Microcontrollers are cheap devices that can be used for real-time control of switch-mode converters. Software design in the assembly language of the microcontroller is important because of the limited resources of the microcontroller. Microcontrollers are best suited for power electronics applications with low bandwidth requirements because the execution time of the software algorithm that realises the digital control law will constitute a considerable delay in the control loop. Digital signal controllers are powerful devices capable of performing arithmetic functions much faster than a microcontroller can. Digital signal controllers are well suited for digital control schemes involving multiple control loops such as digital control of a switch-mode power supply with several converter stages. Customised digital control solutions implemented in application specific integrated circuits are the best solution for high bandwidth digital control of non-isolated DC-DCconverters. A customised digital control solution for a voltage mode control scheme should include a digital pulse width modulator which can generate a pulse width modulated signal with high switching frequency and high resolution, a digital compensator with a short execution time and an analogue to digital converter with a short sampling time. A digital self-oscillating modulator is proposed in the present thesis. The modulator is a free-running modulator which operates without an external carrier signal. Customised digital control solutions offers the best performance for non-isolated DC-DCconverters. The best digital control solution presented in this thesis, which was implemented with the digital self-oscillating modulator, performs comparable to common analogue control IC solutions. It is however possible to achieve an even better performance with an analogue control circuit built with separate analogue components.
Abstract An indirect control variable for improving the control-to-output characteristics of a Pulse Width Modulation (PWM) buck-boost converter is introduced in this letter. The voltage gain and the small-signal model of the buck-boost converter are reviewed. The actual voltage command at one input of the PWM comparator is from the proposed indirect control variable and the peak value of the high-frequency PWM carrier. The resulted voltage gain function appears proportional to this indirect control command. Also the dependence of the DC gain of the control-to-output transfer function on the duty cycle is eliminated. Experimental results conform well to the theoretical analysis. Copyright 2010 John Wiley & Sons, Ltd.
Abstract in spanish Este artículo presenta el diseño, implementación y validación experimental de un emulador controlado digitalmente de pilas de combustible con membrana de intercambio protónico (PEM), tanto para comportamiento estático como dinámico, el cual es fácil de usar y proporciona autonomía y portabilidad a bajo costo. El emulador permite la evaluación de sistemas de potencia y estrategias de control en sistemas basados en pilas de combustible. Para la implementación del (more) emulador se seleccionó, ajustó y validó un modelo matemático apropiado. El modelo es procesado digitalmente en el emulador, el cual genera el comportamiento eléctrico apropiado a la carga. La etapa de potencia fue implementada usando un convertidor DC/DC conmutado de dos inductores, controlado directamente con el sistema de procesamiento digital. El artículo presenta el esquema eléctrico y diagrama de bloques de la etapa de potencia, y el comportamiento del emulador es ilustrado con resultados de simulación. Finalmente, el emulador es validado experimentalmente. Abstract in english This paper presents the design, implementation, and experimental validation of a digitally-controlled emulator of proton exchange membrane (PEM) fuel cells for static and dynamic behavior. The emulator is a low cost, easy to use, and portable device designed to evaluate power systems and control strategies for fuel cell-based generation systems. For the implementation of this emulator, an appropriate mathematical model is chosen, parameterized, and experimentally validate (more) d. The resulting model is processed digitally by the emulator, which generates the appropriate electrical behavior to a load. The emulator power stage is implemented by using a two-inductor step-down DC/DC switching converter, which is controlled directly by the digital processing system. Later, the electrical scheme of the power stage and the block diagram of the system are presented, and the behavior of the emulator is illustrated with a simulation. Finally, the emulator is validated using experimental data.
This paper presented a newly developed flyback buck-boost inverter for photovoltaic (PV) systems in single-phase applications. Inverters are required for grid-connected PV systems to convert DC sources to AC output. The most desired features for small, single-phase grid-connected inverters are low cost, simple structure and wide operation range. This newly developed inverter has a low component count and a simple structure that can accommodate a wide range of input DC voltage. It therefore presents a low cost alternative for small PV systems. The detailed working principles and control strategies of the buck-boost inverter were presented along with computer simulations and experimental findings. The development was based on a study of 2 control strategies regarding voltage pulse-width modulation and hysteresis current control. The operation of the buck-boost inverter has been tested over a wide range of input voltage in both grid-connected and standalone tests. In addition to being suitable for small single-phase PV systems, the novel buck-boost inverter can be controlled by voltage sinusoidal pulse-width modulation (SPWM) and by hysteresis current control in which the inductor current is controlled within specified range of signals. Experimental waveforms have identified the need for improving the output current waveforms in grid-connected applications. It was suggested that further studies using better control strategies are needed to improve the steady state current waveforms and dynamic performance of the inverter. 8 refs., 11 figs.
This is an animation of a capacitor-filtered half-wave rectifier circuit or buckconverter. Voltages and parts of the circuit of this 3-D animated gif are highlighted with different colors. Current is displayed by green arrows indicating directional flow. The animation requires a Web browser or other video player software capable of displaying gif animations. A link provides an optional Quicktime version of this same animation.Other 3-D Circuit Animations can be seen here.
Electrical power system in future uninterruptible power supply (UPS) or electrical vehicle (EV) may employ hybrid energy sources, such as fuel cells and super-capacitors. It will be necessary to efficiently draw the energy from these two sources as well as recharge the energy storage elements by the DC bus. In this paper, a bidirectional isolated DC-DCconverter controlled by phase-shift and duty cycle for the fuel cell hybrid energy system is analyzed and designed. The proposed topology minimizes the number of switches and their associated gate driver components by using two high frequency transformers which combine a half-bridge circuit and a full-bridge circuit together on the primary side. The voltage doubler circuit is employed on the secondary side. The current-fed input can limit the input current ripple that is favorable for fuel cells. The parasitic capacitance of the switches is used for zero voltage switching (ZVS). Moreover, a phase-shift and duty cycle modulation method is utilized to control thebidirectional power flow flexibly and it also makes the converter operate under a quasi-optimal condition over a wide input voltage range. This paper describes the operation principle of the proposed converter, the ZVS conditions and the quasi-optimal design in depth. The design guidelines and considerations about the transformers and other key components are given. Finally, a 1- kW 30~50-V-input 400-V-output laboratory prototype operating at 100 kHz switching frequency is built and tested to verify the effectiveness of the presented converter.
In this paper a modular power electronic transformer (PET) for feeding critical loads is presented. The PE-based transformer is a multi-cellular step-down converter that can directly connect to medium voltage levels on the primary side and provide a low voltage, highly stable interface for consumer applications. The presented structure consists of three stages: a cascaded H-bridge (CHB) rectifier, an isolation stage, and an output stage. The CHB rectifier serves as an active rectifier to ensure that the input current is sinusoidal, and it converts the high AC input voltage to low DC voltages. The isolated DC/DCconverters are then connected to the DC links and provide galvanic isolation between the HV and LV sides. Finally, a three-phase inverter generates the AC output with the desired amplitude and frequency. This paper introduces a new control strategy to maintain DC voltage balance among the CHB converter cells, even if the attached loads are different. The effects of voltage offsets and device mismatches on the equal load-current sharing are investigated, and an active load-current sharing method is presented to balance the load power among the parallel-output cells. The validity of the proposed controllers and the PET performance are verified by simulation and experimental results. (author)
In this paper, a random-switching controller using chaos generators is employed in a DC-DCconverter. By fluctuating the timing of the clock pulse for the converter, the controller can reduce the peaks of the power-spectrum of the output voltage. Different from the conventional controllers, the proposed controller exploits random noise generated by chaos generators. Therefore, the proposed controller can achieve effective reduction of the noise spectrum peak with small size of circuit. Concerning the controller designed by a 1.2 ?m CMOS technology, SPICE simulations are performed to investigate the characteristics of the circuit. The SPICE simulations show that 1. the noise spectrum peak of the output voltage of the power converter is reduced more than 10 dB by employing the controller and 2. the circuit size for the proposed controller is smaller than that for the conventional controller. Furthermore, the validity of the circuit design is confirmed by experiments. The proposed controller will be applicable for most of switching power converters without design modification for the other parts.
This paper presents a high efficiency non-isolated bidirectional converter which can be employed as an interface circuit between ultracapacitors or batteries and DC bus voltage. All semiconductor devices in the proposed converter are soft switched while the control circuit remains PWM. So, the energy conversion through the converter is highly efficient. The proposed converter acts as a zero-voltage transition (ZVT) buck to charge an ultracapacitor or battery and acts as a ZVT boost to discharge an ultracapacitor or battery. The performance of the proposed converter with respect to abrupt load and operating mode change is shown through computer simulation results. The results confirm the aforementioned advantages and features of the proposed converter.
Abstract in spanish Este artículo presenta el modelado y control de sistemas fotovoltaicos considerando perturbaciones en la irradiación solar y en la carga. Se consideran tres casos: sistemas con elevación/reducción usando un convertidor Buck/Boost no inversor, sistemas exclusivamente reductores usando un convertidor Buck, y sistemas exclusivamente elevadores usando un convertidor del Boost. Los sistemas son modelados para diseñar controladores de voltaje que regulen el panel fotovolta (more) ico de acuerdo con la referencia dada por un algoritmo para seguimiento del punto de máxima potencia, el cual busca maximizar la potencia producida. Los modelos propuestos son validados a partir del análisis de su respuesta en frecuencia, y el diseño de los controladores se validada a través de simulaciones detalladas realizadas con un simulador estándar de electrónica de potencia. Finalmente, la aplicabilidad de la solución propuesta se valida con resultados experimentales. Abstract in english This paper presents the modeling and control of photovoltaic systems considering disturbances in solar irradiance and load. Three cases are addressed: step-up/step-down systems using a non-inverting Buck-Boost converter interface, step-down systems using a Buckconverter interface, and step-up systems using a Boost converter. Control-oriented models are analytically derived to design controllers that regulate the voltage of the photovoltaic panel in agreement with the ref (more) erence provided by a maximum power point tracking algorithm, aimed at maximizing power production. The proposed models are validated by means of frequency response analyses, and the designed controllers are validated by means of detailed simulations performed in standard power electronics software. Finally, experimental results illustrate the applicability of the proposed approach to real cases.
In this paper, an interleaved soft-switched active-clamped L-L type current-fed half-bridge isolated dc-dcconverter has been proposed. The L-L type active-clamped current-fed converter is able to maintain zero-voltage switching (ZVS) of all switches for the complete operating range of wide fuel cell stack voltage variation at full load down to light load conditions. Active-clamped circuit absorbs the turn-off voltage spike across the switches. Half-bridge topology maintains higher efficiency due to lower conduction losses. Soft-switching permits higher switching frequency operation, reducing the size, weight and cost of the magnetic components. Interleaving of the two isolated converters is done using parallel input series output approach and phase-shifted modulation is adopted. It reduces the input current ripple at the fuel cell input, which is required in a fuel cell system and also reduces the output voltage ripples. In addition, the size of the magnetic/passive components, current rating of the switches and voltage ratings of the rectifier diodes are reduced. (author)
We examine a thermoelectric harvester that converts electrical energy from the naturally occurring temperature difference between ambient air and large thermal storage capacitors such as building walls or the soil. For maximum power output, the harvester design is implemented in two steps: source matching of the thermal and electrical interfaces to the energy source (system level) followed by load matching of the generator to these interfaces (subsystem level). Therefore, we measure thermal source properties such as the temperature difference, the air velocity, and the cutoff frequency in two application scenarios (road tunnel and office building). We extend a stationary model of the harvester into the time domain to account for transient behavior of the source. Based on the model and the source measurements, we perform the source and load matching. The resulting harvester consists of a pin fin heat sink with a thermal resistance of 6.2 K/W and a cutoff frequency 2.5 times greater than that of the source, a thermoelectric generator, and a DC/DC step-up converter starting at a total temperature difference of only ? T = 1.2 K. In a final road tunnel field test, this optimized harvester converts 70 mJ of electrical energy per day without any direct solar irradiation. The energy provided by the harvester enables 415 data transmissions from a wireless sensor node per day.
Current trends in satellite design are focused on developing small, reliable, and inexpensive spacecraft. To that end, a modular power management and distribution system is proposed which will help transition the aerospace industry towards an assembly line approach to building spacecraft. The modular system is based on an innovative DC voltage boost converter called the Series Connected Boost Unit (SCBU). The SCBU uses any isolating DC-DCconverter and adds a unique series connection. This simple modification provides the SCBU topology with many advances over existing boost converters. Efficiencies of 94--98%, power densities above 1,000 W/kg, and inherent fault tolerance are just a few of the characteristics presented. Imitations of the SCBU technology are presented, and it is shown that the SCBU makes an ideal photovoltaic array regulator. A set of photovoltaic power system requirements are presented that can be applied to almost any low Earth orbit satellite. Finally, a modular design based on the series connected boost unit is outlined and functional descriptions of the components are given.
Abstract in spanish Se presenta el diseño estático de un convertidor reductor-elevador bidireccional con tres conmutadores y conexión en cascada. La principal aplicación del convertidor es la administración de baterías en sistemas de alimentación ininterrumpida, controlando el flujo de energía y regulando la tensión de alimentación DC durante los diferentes modos de operación de la batería como fuente y sumidero. Abstract in english This paper shows a buck-boost converter static design with 3 switches and cascade connection. The main application of the converter is the battery management on uninterruptible power supplies, controlling energy flow and regulating the DC supply voltage for the different battery operation modes as source and sink.
In this paper, artificial neural networks are used to elaborate non-linear control of the average output voltage of Buck and Boost converters. The training of the regulator is based on the adjustment technique used by indirect adaptative command structures. These techniques require a system model and performances of inputs/outputs and state models are compared. It is shown that this approach allows to generate non-linear regulators for the converters under study, but it is preferable to introduce some modifications in order to facilitate the training of the regulator. (J.S.) 4 refs.
To raise the utilization ratio of lithium-ion battery in portable devices, a novel green-switch controller IC is proposed to constitute a 4-switch cascade buck-boost prototype, which is capable of outputting non-inverting step down and step up voltages. According to the relations between the input and output voltages through duty ratio, a finite state machine automatically determines the work method of converter namely buck method, boost method or transition method by combining peak and valley current programmed mode so as to improve the line regulation over the entire input voltage range. A three-phase seamless transition method is introduced into the controller. Its additional advantage is to lower output ripples. Furthermore, a special burst mode is added to reduce the power consumption...
A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFET junction capacitances and the reverse recovery of diodes, and enables the converters to operate at high frequencies. A dc analysis of the converter is carried out. The duality relationship between the zero-current switching technique and the zero-voltage switching technique is derived. The two techniques are compared using an example showing the duality between a current-mode quasi-resonant Buckconverter and a voltage-mode quasi-resonant boost converter. A 5-MHz 50 V to 5 V flyback converter employing the zero-voltage switching technique has been implemented. The circuit contains the smallest number of components possible, and yet maintains high efficiency at high switching frequency.
Abstract in portuguese Este artigo propõe uma metodologia de projeto aprimorada para determinação dos componentes auxiliares para o conversor ZVT CC-CC PWM snubber assisted auxiliary switch. O procedimento de projeto proposto é baseado na redução das perdas de condução no circuito auxiliar. Isto é somente possível devido à localização do capacitor snubber de bloqueio, o qual é compartilhado por ambas as chaves ativas. Através do procedimento de projeto proposto o rendimento do co (more) nversor pode ser aumentado. Uma análise comparativa do rendimento é apresentada e os resultados experimentais, obtidos de protótipos de laboratório de 1 kW, 100 kHz, mostram uma melhoria relevante em relação ao rendimento apresentado pelo projeto original. Além disso, os resultados experimentais também confirmam que o projeto proposto para o conversor ZVT snubber assisted auxiliary switch torna-o competitivo em relação ao conversor ZVT PWM com fonte auxiliar de tensão constante (true PWM ZVS pole). Abstract in english This paper proposes an improved design to calculate the snubber auxiliary elements of ZVT DC-DC PWM converters with snubber assisted auxiliary switch. The proposed improved design guidelines are based on the reduction of the conduction losses through the auxiliary circuit. It is accomplished by the unique location of the turn-off snubber capacitor, which is shared by both active switches. By means of this improved design guidelines the converter efficiency can be increase (more) d. An efficiency comparative analysis is carried out and the experimental results, obtained from 1 kW, 100 kHz laboratory prototypes, show a relevant improvement in converter efficiency compared to the original converter design. In addition, experimental results also confirm that with the improved design the ZVT PWM converters with snubber assisted auxiliary switch can be competitive with ZVT PWM converters with constant auxiliary voltage source (True PWM ZVS pole).
This paper describes a simple photo-voltaic (PV) tracking system which has been designed and manufactured using a pyramidal stand as a base. A rotating unit consisting of two pairs of modules fixed at an angle of 170{sup o} between them was installed at the upper edge of the stand. The four modules and a DC motor were connected to a bridge circuit making the system sensitive to solar tracking. The PV tracker has a DC-DC (24/2 V) converter, DC-AC (24/220 V) inverter and a battery. The modules are able to provide a maximum power of {approx}100 W, which feeds the converter, inverter and DC motor. Wind resistance of the tracker is quite low. The total area of the four modules is 1.26 m{sup 2}. The inclination angle between the modules and the horizontal plane is adjustable (34{sup o}{+-}11{sup o}) and the tracking angle is 120{sup o}. The system can track solar motion with an error of {+-}10{sup o}. The designed PV tracking system, with modules fixed at an angle of 170{sup o} to feed the load as well as the DC motor, exhibited it to be an efficient energy-conversion system. The fabricated system offers low wind resistance. The cost analysis data revealed that the proposed design was very economical and cost effective. (author)
Abstract in spanish El propósito de este artículo es doble. Por un lado, se presentan conceptos básicos de circuitos conmutados para diseñar un convertidor CD-CD y, por el otro, se rescatan definiciones de electrónica de potencia asociadas a redes eléctricas simples. En el análisis de esas redes es necesario tomar en cuenta no solo las no idealidades de los convertidores sino también cómo minimizar pérdidas de potencia. Porque las perdidas de potencia pueden ser minimizadas aumenta (more) ndo la frecuencia de reloj de los convertidores conmutados, se presentan resultados experimentales de generadores de reloj. Estos circuitos fueron implementados con componentes de bajo costo Abstract in english The purpose of this paper is twofold. On one hand, basics on switched circuits for designing a DC-DCconverter are presented and, on the other hand, power electronics definitions associated with simple electrical networks are mentioned. In the analysis of these networks, it is necessary to take into account not only converters' non-idealities but also how to minimize power losses. Since power losses may be minimized by increasing the clock frequency of switched-based conv (more) erters, experimental results of basic clock generators are presented. These generators were implemented with low-cost components
In the AC-AC power conversion system connecting two alternating current systems such as commercial AC lines and AC motors, etc., a PAM-PWM controlling system was proposed to obtain sinusoidal output by adding an operation to improve the waveform of inverter output to that of a DC-DCconverter while making the inverter get a wide period of repose, then the output voltage waveform was analysed. From the result of analysis, it was found out that the component included in the output voltage waveform consisted of the fundamental component and the sidebands of the carrier frequency and did not contain higher harmonics; also, the amplitude of the fundamental component increased 15 % more than that of a conventional sine-wave inverter, etc. Furthermore, a trial manufacture and an experiment of a sinusoidal output PAM inverter being composed of MOSFET were carried out. As a result, it was found out that the size of the heat dissipating equipment of the inverter could be minimized since each converter arm reposed the commutative operation during 240[degree] of the output cycle and the heat generated in the inverter was reduced. 10 refs., 9 figs., 1 tab.
Photovoltaic energy has nowadays an increased importance in electrical power applications, since it is considered as an essentially inexhaustible and broadly available energy resource. However, the output power provided via the photovoltaic conversion process depends on solar irradiation and temperature. Therefore, to maximize the efficiency of the photovoltaic energy system, it is necessary to track the maximum power point of the PV array. The present paper proposes a maximum power point tracker (MPPT) method, based on fuzzy logic controller (FLC), applied to a stand-alone photovoltaic system. It uses a sampling measure of the PV array power and voltage then determines an optimal increment required to have the optimal operating voltage which permits maximum power tracking. This method carries high accuracy around the optimum point when compared to the conventional one. The stand-alone photovoltaic system used in this paper includes two bi-directional DC/DCconverters and a lead-acid battery bank to overcome the scare periods. One converter works as an MPP tracker, while the other regulates the batteries state of charge and compensates the power deficit to provide a continuous delivery of energy to the load. The Obtained simulation results show the effectiveness of the proposed fuzzy logic controller. (author)
A 1 MW dc-dc power converter has been designed which has an input voltage of 5 kV +/-3 percent, an output voltage of 100 kV +/- 0.25 percent, and a run time of 1000 s at full power. The estimated system mass is 83.8 kg, giving a power density of 11.9 kW/kg. The system exceeded the weight goal of 10 kW/kg through the use of innovative components and system concepts. The system volume is approximately 0.1 cu m, and the overall system efficiency is estimated to be 87 percent. Some of the unique system features include a 50-kHz H-bridge inverter using MOS-controlled thyristors as the switching devices, a resonance transformer to step up the voltage, open-cycle cryogenic hydrogen gas cooling, and a nonrigid, inflatable housing which provides on-demand pressurization of the power converter local environment. This system scales very well to higher output powers. The weight of the 10-MW system with the same input and output voltage requirements and overall system configuration is estimated to be 575.3 kg. This gives a power density of 17.4 kW/kg, significantly higher than the 11.9 kW/kg estimated at 1 MW.
The design and testing of a purely super-capacitor energy storage device as auxiliary power source in electrical vehicle applications having a PEM fuel cell as main source are presented. The two control strategies are explained. The control algorithms are that fuel cell is simply operating in almost steady state conditions in order to lessen the mechanical stresses of fuel cell and to ensure a good synchronization between fuel flow and fuel cell current. Super-capacitors are functioning during absence of energy from fuel cell, transient energy delivery or transient energy recovery. The system utilizes two modules of SAFT super-capacitive storage device. This device is connected to a 42 V DC bus by a 2-quadrant dc/dcconverter, and fuel cell is connected to the dc bus by a boost converter. The system structure is realized by analogical current loops and digital control (dSPACE) for voltage loops and estimation algorithms. Experimental results with a 500 W PEM fuel cell point out the slow dynamics naturally of fuel cell because of thermodynamic and mechanical operation, and also substantiate that the super-capacitors can improve dynamics and power conditioning for automotive electrical system. (author)
A novel fuel cell based inverter for residential systems was presented. The inverter consisted of an isolated ZVS current-fed half bridge DC-DCconverter cascaded with a single phase quasi-resonant voltage source inverter. The 400 V DC output was converted to 220 V 50 Hz single-phase AC by means of a quasi-resonant PWM inverter stage. An output LC filter was used to produce a THD of AC waveform. The inverter stage was developed from a classical VSI inverter with an L-type full-wave resonant switch. The structure did not require any clamping circuit and was able to guarantee the stable oscillation of resonant links as well as the soft switching of the inverter only by using a discrete pulse width modulation of the inverter grid interface. This paper provided an analysis of the proposed topology of the inverter grid interface. The analysis was divided into 7 modes. Operation modes were based on the assumption that the currents were continuous, that all switching devices and resonant components were ideal. Transformer leakage inductance and magnetizing inductance were neglected. Four operating modes in each resonant cycle were considered, and solutions were presented for all modes. It was concluded that the inverter performed well in all the analyzed power ranges. 9 refs., 1 tab., 11 figs.
The trend toward high power density, high operating frequency, and low profile in power converters has exposed a number of limitations in the use of conventional wire-wound magnetic component structures. A planar magnetic is a low-profile transformer or inductor utilizing planar windings, instead of the traditional windings made of Cu wires. In this paper, the most important factors for planar transformer (PT) design including winding loss, core loss, leakage inductance, and stray capacitance have individually been investigated. The tradeoffs among these factors have to be analyzed in order to achieve optimal parameters. Combined with an application, four typical winding arrangements have been compared to illustrate their advantages and disadvantages. An improved interleaving structure with optimal behaviors is proposed, which constructs the top layer paralleling with the bottom layer and then in series with the other turns of the primary, so that a lower magnetomotive force ratio $m$ can be obtained, as wellas minimized ac resistance, leakage inductance, and even stray capacitance. A 1.2-kW full-bridge dc–dcconverter prototype employing the improved PT structure has been constructed, over 96% efficiency is achieved, and a 2.7% improvement, compared with the noninterleaving structure, is obtained.
This paper describes electrical design criteria and first operational results a 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching 20 kHz polyphase bridge, boost converter/modulator for klystron pulse application. The DC-DCconverter derives the buss voltages from a standard 13.8 kV to 2300 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. PWM (pulse width modulation) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt-peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. A review of these design parameters and the first results of the performance characteristics will be presented.
This paper describes the first operational results of the 140 kV, 1 MW average, 11 MW peak, zero-voltage-switching, 20 kHz polyphase bridge, boost converter-modulator for klystron pulse application. The DC-DCconverter derives the buss voltages from a standard 13.8 kV to 2100 Y substation cast-core transformer. Energy storage and filtering is provided by self-clearing metallized hazy polypropylene traction capacitors. Three ''H-Bridge'' Insulated Gate Bipolar Transistor (IGBT) switching networks are used to generate the polyphase 20 kHz transformer primary drive waveforms. The 20 kHz drive waveforms are chirped the appropriate duration to generate the desired klystron pulse width. Pulse-Width Modulation (PWM) of the individual 20 kHz pulses is utilized to provide regulated output waveforms with adaptive feedforward and feedback techniques. The boost transformer design utilizes amorphous nanocrystalline material that provides the required low core loss at design flux levels and switching frequencies. Resonant shunt peaking is used on the transformer secondary to boost output voltage and resonate transformer leakage inductance. With the appropriate transformer leakage inductance and peaking capacitance, zero-voltage-switching of the IGBT's is attained, minimizing switching losses. Reviews of these design parameters and an examination of the first operational results will be performed.
The distributed renewable energy generation and utilization are constantly growing, and are expected to be integrated with the conventional grid. The growing pressure for innovative solutions will demand power electronics to take an even larger role in future electric energy delivery and management systems, since power electronics are required for the conversion and control of electric energy by most dispersed generation systems Furthermore, power electronics systems can provide additional intelligent energy management, grid stability and power quality capabilities. Medium-voltage isolated dc-dcconverter will become one of the key interfaces for grid components with moderate power ratings. To address the demand of medium voltage (MV) and high power capability for future electric energy delivery and management systems, the power electronics community and industry have been reacting in two different ways: developing semiconductor technology or directly connecting devices in series/parallel to reach higher nominal voltages and currents while maintaining conventional converter topologies; and by developing new converter topologies with traditional semiconductor technology, known as multilevel converters or modular converters. The modular approach uses the well-known, mature, and cheaper power semiconductor devices by adopting new converter topologies. The main advantages of the modular approach include: significant improvement in reliability by introducing desired level of redundancy; standardization of components leading to reduction in manufacturing cost and time; power systems can be easily reconfigured to support varying input-output specifications; and possibly higher efficiency and power density of the overall system. Input-series output-parallel (ISOP) modular configuration is a good choice to realize MV to low voltage (LV) conversion for utility application. However, challenges still remain. First of all, for the high-frequency MV utility application, the low switching loss and conduction loss are must-haves for high efficiency, while bidirectional power flow capability is a must for power management requirement. To address the demand, the phase-shift dual-halfbridge (DHB) is proposed as the constituent module of ISOP configuration for MV application. The proposed ISOP DHB converter employs zero-voltage-switching (ZVS) technique combined with LV MOSFETs to achieve low switching and conduction losses under high frequency operation, and therefore high efficiency and high power density, and bidirectional power flow as well. Secondly, a large load range of high efficiency is desired rather than only a specific load point due to the continuous operation and large load variation range of utility application, which is of high importance because of the rising energy cost. This work proposes a novel DHB converter with an adaptive commutation inductor. By utilizing an adaptive inductor as the main energy transfer element, the output power can be controlled by not only the phase shift but also the commutation inductance, which allows the circulating energy to be optimized for different load conditions to maintain ZVS under light load conditions and minimize additional conduction losses under heavy load conditions as well. As a result, the efficiency at both light and heavy load can be significantly improved compared with the conventional DHB converter, and therefore extended high-efficiency range can be achieved. In addition, current stress of switch devices can be reduced. The theoretical analysis is presented and validated by the experimental results on a 50 kHz, 1 kW dc-dcconverter module. Thirdly, input-voltage sharing and output-current sharing are critical to assure the advantages of the ISOP modular configuration. To solve this issue, an identically distributed control scheme is proposed in this work. The proposed control scheme, using only one distributed voltage loop to realize both input-voltage and output-current sharing, provides plug-and-play capability, possible high-level fault tolerance, and easy implementatio
The reluctance interior permanent magnet (RIPM) motor is currently used by many leading auto manufacturers for hybrid vehicles. The power density for this type of motor is high compared with that of induction motors and switched reluctance motors. The primary drawback of the RIPM motor is the permanent magnet (PM) because during high-speed operation, the fixed PM produces a huge back electromotive force (emf) that must be reduced before the current will pass through the stator windings. This reduction in back-emf is accomplished with a significant direct-axis (d-axis) demagnetization current, which opposes the PM's flux to reduce the flux seen by the stator wires. This may lower the power factor and efficiency of the motor and raise the requirement on the alternate current (ac) power supply; consequently, bigger inverter switching components, thicker motor winding conductors, and heavier cables are required. The direct current (dc) link capacitor is also affected when it must accommodate heavier harmonic currents. It is commonly agreed that, for synchronous machines, the power factor can be optimized by varying the field excitation to minimize the current. The field produced by the PM is fixed and cannot be adjusted. What can be adjusted is reactive current to the d-axis of the stator winding, which consumes reactive power but does not always help to improve the power factor. The objective of this project is to avoid the primary drawbacks of the RIPM motor by introducing brushless field excitation (BFE). This offers both high torque per ampere (A) per core length at low speed by using flux, which is enhanced by increasing current to a fixed excitation coil, and flux, which is weakened at high speed by reducing current to the excitation coil. If field weakening is used, the dc/dc boost converter used in a conventional RIPM motor may be eliminated to reduce system costs. However, BFE supports a drive system with a dc/dc boost converter, because it can further extend the constant power speed range of the drive system and adjust the field for power factor and efficiency gains. Lower core losses at low torque regions, especially at high speeds, are attained by reducing the field excitation. Safety and reliability are increased by weakening the field when a winding short-circuit fault occurs, preventing damage to the motor. For a high-speed motor operating at 16,000-revolutions per minute (rpm), mechanical stress is a challenge. Bridges that link the rotor punching segments together must be thickened for mechanical integrity; consequently, increased rotor flux leakage significantly lowers motor performance. This barrier can be overcome by BFE to ensure sufficient rotor flux when needed.
Commercially available silicon carbide (SiC) Schottky diodes from different manufacturers rated at 200, 300, 600, and 1200 V, were electrically tested and characterized as a function of temperature up to 300 C. Electrical tests included both steady state and dynamic tests. Steady state tests produced forward and reverse I-V characteristic curves. Transient tests evaluated the switching performance of the diodes in either a hard-switched DC to DC buckconverter or a half-bridge boost converter. For evaluation and comparison purposes, the same tests were performed with current state-of-the-art ultra fast silicon (Si) pn-junction diodes of similar ratings and also a Si Schottky diode. The comparisons made were forward voltage drop at rated current, reverse current at rated voltage, and turn-off peak reverse recovery current and reverse recovery time. In addition, efficiency measurements were taken for the buck DC to DC converter using both the SiC Schottky diodes and the Si pn-junction diodes at different temperatures and frequencies. The test results showed that at high temperature, the forward voltage drop for SiC Schottky diodes is higher than the forward drop of the ultra fast Si pn-junction diodes. As the temperature increased, the forward voltage drop of the SiC Schottky increased while for the ultra fast Si pn-junction diodes, the forward voltage drop decreased as temperature increased. For the elevated temperature steady state reverse voltage tests, the SiC Schottky diodes showed low leakage current at their rated voltage. Likewise, for the transient tests, the SiC Schottky diodes displayed low reverse recovery currents over the range of temperatures tested. Conversely, the Si pn-junction diodes showed increasing peak reverse current values and reverse recovery times with increasing temperature. Efficiency measurements in the DC to DC buckconverter showed the advantage of the SiC Schottky diodes over the ultra fast Si pn-junction diodes, especially at the higher temperatures and higher frequencies.
This paper deals with a Lyapunov based control principle in a hybrid energy storage system for electric vehicle. The storage system consists on fuel cell (FC) as a main power source and a supercapacitor (SC) as an auxiliary power source. The power stage of energy conversion consists on a boost converter connected with the main source and a buck-boost converter connected with the auxiliary source. The converters share the same dc bus which is connected to the traction motor through an inverter. The aim is controlling power converters in order to satisfy the following requirements: i) tight dc bus voltage regulations, ii) perfect tracking of SC current to its reference, and iii) asymptotic stability of the closed loop system. It is clearly shown, using formal analysis and simulations that the designed controller meets all the objectives.
Device comprising an electric power converter circuit for converting electric energy. The converter circuit comprises a switch arrangement with two or more controllable electric switches connected in a switching configuration and controlled so as to provide a current drive of electric energy from an associated electric source connected to a set of input terminals. This is obtained by the two or more electric swiches being connected and controlled to short-circuit the input terminals during a part of a switching period. Further, a low pass filter with a capacitor and an inductor are provided to low pass the output from the switch arrangement and designed such that a high impedance at a frequency range below the switching frequency is obtained, seen from the output terminals. Switches implemented by normally-on-devices are preferred, e.g. in the form of a JFET. The converter circuit may be in different configurations such as half bridge buck, full bridge buck, half bridge boost, or full bridge boost. A current driven conversion is advantageous for high efficient energy conversion from current sources such as solar cells or where a voltage source is connected through long cables, e.g. powerline cables for long distance transmission of electric energy. In many applications the total size of filter components (capacitors and inductors) can be reduced compared to voltage driven topologies. One application is an audio amplifier arranged to drive a loudspeaker.
In this paper we clarify for the boost and the buck-boost converter that the ripple effect is not ignorable for the frequency response, and reveal that it causes the unexpected characteristics where either the phase lag or the phase lead appears depending on the shape of waveform of the ramp generator in the PWM circuit. Eventually the phase margin for the stability drastically changes depending on the slope direction (normal or reverse) of the sawtooth waveform of the ramp generator even in the same circuit configuration. For the ripple effects we propose the general analysis model and analyze them of the boost and the buck-boost converters. As the result we identify that the ripple effects are caused mainly by the variation of the slope and the average of the ripple, and reveal that the both converters have the asymmetric characteristics for the slope direction of the sawtooth waveform of the ramp generator and there is more advantage for the stability in case of the reverse slope direction than in case of the normal one. It also clarified that the effect of ESR of the output capacitor of the converter on the frequency response is different according to the shape of the sawtooth waveforms. The proposed analysis method is validated by the experiments and simulations.
Instantaneous power goes through zero twice every cycle. – Low frequency ... allows for regulation of the output bus voltage to be performed ... Switched User Loads ... Shows effectiveness of the DC-DC convertor current ripple suppression ...
In order to reduce power consumption of electronic equipment in stand-by mode, idle-mode and sleep-mode, a simple efficiency improvement technique for switching regulator in light load region is proposed. In this technique, under the light load, the small switching elements in a MOSFET driver circuit are used instead of the switching elements in a main regulator circuit to reduce driving losses. Of course, under the load heavier than light load, the MOSFET driver drives the switching elements in the main regulator circuit. The efficiency of a 2.5V/5A prototype buckconverter is improved from 47.1% to 72.7% by using the proposed technique.
This paper describes the design of a line conditioner for three phase ac-ac power conditioning. It is based on a three phase PWM ac-ac buck-boost converter. It has several advantages in terms of size, weight, efficiency and performance over state of the art line conditioners. Design specifications and relationships are presented. Analytical formulae for determining the efficiency of the line conditioner are presented. A controller design which features fast transient response is developed. Operation of the line conditioner in the presence of voltage sags and surges, load addition and rejection is illustrated by means of simulation. Experimental results verifying the operation of the power circuit are also presented.
This paper describes a maximum power point tracking (MPPT) circuit for thermoelectric generators (TEG) without a digital controller unit. The proposed method uses an analog tracking circuit that samples the half point of the open-circuit voltage without a digital signal processor (DSP) or microcontroller unit for calculating the peak power point using iterative methods. The simulation results revealed that the MPPT circuit, which employs a boost-cascaded-with-buckconverter, handled rapid variation of temperature and abrupt changes of load current; this method enables stable operation with high power transfer efficiency. The proposed MPPT technique is a useful analog MPPT solution for thermoelectric generators.
Small signal low frequency linear average model is derived for a multi-loop controlled two-winding buck/boost converter employing average techniques and the describing function method. The model reveals that a well-designed multi-loop control can provide a second-order zero adaptive to output filter parameter changes due to component tolerances, temperature changes, aging, and the effect of duty cycle modulation. It also can provide stabilization effect by shifting the positive zero to the left-half S-plane. Design guidelines are formulated to optimize regulator-loop dependent characteristics.
This paper discusses a new approach to making hybrid power electronic circuits by combining a low-temperature (850 C to 950 C) co-fired ceramic (LTCC) substrate, planar LTCC ferrite transformers/inductors and integrated passive components into a multilayer monolithic package using a ferrite-based LTCC material system. A ferrite tape functions as the base material for this LTCC system. The material system includes physically and chemically compatible dielectric paste, dielectric tape and conductor materials which can be co-fired with the base ferrite LTCC tape to create sintered devices with excellent magnetic coupling, high permeability ({approx}400), high resistivity (> 10{sup 12} {Omega} {center_dot} cm) and good saturation ({approx}0.3 T). The co-fired ferrite and dielectric materials can be used as a substrate for attaching or housing semiconductor components and other discrete devices that are part of the power electronics system. Furthermore, the ability to co-fire the ferrite with dielectric and conductor materials allows for the incorporation of embedded passives in the multilayer structure to create hybrid power electronic circuits. Overall this thick film material set offers a unique approach to making hybrid power electronics and could potentially allow a size reduction for many commercial dc-dcconverter and other power electronic circuits.
This paper discusses a new approach to making hybrid power electronic circuits by combining a low-temperature (850 C to 950 C) co-fired ceramic (LTCC) substrate, planar LTCC ferrite transformers/inductors and integrated passive components into a multilayer monolithic package using a ferrite-based LTCC material system. A ferrite tape functions as the base material for this LTCC system. The material system includes physically and chemically compatible dielectric paste, dielectric tape and conductor materials which can be co-fired with the base ferrite LTCC tape to create sintered devices with excellent magnetic coupling, high permeability ({approx}400), high resistivity (> 10{sup 12} {Omega} {center_dot} cm) and good saturation ({approx}0.3 T). The co-fired ferrite and dielectric materials can be used as a substrate for attaching or housing semiconductor components and other discrete devices that are part of the power electronics system. Furthermore, the ability to co-fire the ferrite with dielectric and conductor materials allows for the incorporation of embedded passives in the multilayer structure to create hybrid power electronic circuits. Overall this thick film material set offers a unique approach to making hybrid power electronics and could potentially allow a size reduction for many commercial dc-dcconverter and other power electronic circuits.
This paper described a hardware-in-the-loop (HIL) validation simulation system designed to evaluate hybrid control strategies. The system was designed to reduce development costs and improve the safety of hybrid vehicle control systems. Model-based design processes for power trains typically include a series of processes to assess the real time and physical limitations of control systems prior to in-vehicle testing. The study used a 70 kW nickel metal hydride battery; a 67 kW 3-phase induction traction motor; and, a high voltage DC-DCconverter within a fuel cell Chevrolet Equinox. Two physical vehicle controllers were used to interface with the virtual vehicle simulation in real time. System performance was monitored with a supervisory computer. A software in the loop (SIL) process was conducted to assess torque control and regenerative braking algorithm validation. An analysis of the controller code showed that a Simulink-native integrator block was updating too slowly. A custom integration term calculation was written. The charge control was then validated and tuned. It was concluded that use of the HIL system mitigated the risk of component damage through the identification and correction of unstable control logic. 10 refs., 2 tabs., 10 figs.
Superconducting accelerators, such as the International Linear Collider (ILC), rely on very high Q accelerating cavities to achieve high electric fields at low RF power. Such cavities have very narrow resonances: a few kHz with a 1.3GHz resonance frequency for the ILC. Several mechanical factors cause tune shifts much larger than this: pressure variations in the liquid helium bath; microphonics from pumps and other mechanical devices; and for a pulsed machine such as the ILC, Lorentz force detuning (pressure from the contained RF field). Simple passive stiffening is limited by many manufacturing and material considerations. Therefore, active tuning using piezo actuators is needed. Here we study a supply for their operation. Since commercial power amplifiers are expensive, we analyzed the characteristics of four power amplifiers: (iPZD) built by Istituto Nazionale di Fisica Nucleare (Sezione di Pisa); and a DC-DCconverter power supply built in Fermilab (Piezo Master); and two commercial amplifiers, Piezosystem jena and Piezomechanik. This paper presents an analysis and characterization of these amplifiers to understand the cost benefit and reliability when using in a large scale, pulsed beam accelerator like the ILC.
This paper presents the design and implementation of a supply and process-insensitive 12-bit Digital Pulse Width Modulator (DPWM) for digital DC-DCconverters. The DPWM is realized by a ring oscillator-based segmented tapped delay line and a counter-comparator. The number of delay cells required is reduced by employing a proposed delay cell reuse technique. The ring oscillator of the tapped delay line is made insensitive to supply and process variation by biasing the differential delay cells with a supply-insensitive replica bias circuit. Simulation results show that the variation of the switching frequency of the DPWM at 1.02MHz is 0.4% for supply voltage variation between 1.5V and 2.5V and 0.95% over the temperature range from -40°C to 90°C. Monte-Carlo simulation was also performed to account for the effect of mismatch between the transistors of the ring oscillator. The worst case delay of the delay cells is 0.87% for ±5% (3-?) mismatch. The design was fabricated in CMOS 0.18µm process and the fabricated DPWM achieved a supply sensitivity of 0.82% and a current consumption of 14µA.
There is vital need for a compact, lightweight, and efficient energy-storage system that is both affordable and has an acceptable cycle life for the large-scale production of electric vehicles (EVs) and hybrid electric vehicles (HEVs). Most of the current research employs a battery-storage unit (BU) combined with a fuel cell (FC) stack in order to achieve the operating voltage-current point of maximum efficiency for the FC system. A system block diagram is shown in Fig.1.1. In such a conventional arrangement, the battery is sized to deliver the difference between the energy required by the traction drive and the energy supplied by the FC system. Energy requirements can increase depending on the drive cycle over which the vehicle is expected to operate. Peak-power transients result in an increase of losses and elevated temperatures which result in a decrease in the lifetime of the battery. This research will propose a novel two-input direct current (dc) dc to dc converter to interface an additional energy-storage element, an ultracapacitor (UC), which is shown in Fig.1.2. It will assist the battery during transients to reduce the peak-power requirements of the battery.
Considering a set of two coupled nonautonomous differential equations with discontinuous right-hand sides describing the behavior of a DC/DC power converter, we discuss a border-collision bifurcation that can lead to the birth of a two-dimensional invariant torus from a stable node equilibrium point. We obtain the chart of dynamic modes and show that there is a region of parameter space in which the system has a single stable node equilibrium point. Under variation of the parameters, this equilibrium may disappear as it collides with a discontinuity boundary between two smooth regions in the phase space. The disappearance of the equilibrium point is accompanied by the soft appearance of an unstable focus period-1 orbit surrounded by a resonant or ergodic torus. Detailed numerical calculations are supported by a theoretical investigation of the normal form map that represents the piecewise linear approximation to our system in the neighbourhood of the border. We determine the functional relationships between the parameters of the normal form map and the actual system and illustrate how the normal form theory can predict the bifurcation behaviour along the border-collision equilibrium-torus bifurcation curve.
In this paper, a novel strategy of maximum power point tracking is presented for photovoltaic power generation systems based on Fibonacci search algorithm to realize simple control system to track the real maximum power point even under non-uniform or for rapidly changing insolation conditions. The Fibonacci search technique was modified in order to apply to time-variant P-V characteristics of the PV array. It is proved experimentally and through simulation results that the algorithm has good performances and very fast response even for partial shaded PV modules. The proposed technique can be applied to various types of PV power conditioners including dc-dc and dc-ac converters. It can be commonly used instead of the conventional MPPT techniques. This method requires neither the measurement of temperature and insolation level nor prior knowledge about the model of the used photovoltaic panel. The proposed method can track the global maximum power point in most cases by doing a wide-range search and more power can be extracted with partial shaded PV modules as compared to the other methods. Simulation and experimental results are presented to prove the feasibility of the proposed technique. (author)
Abstract in english Recent technological developments have created new devices that could improve and simplify the construction of stimulus isolators. HEXFET transistors can switch large currents and hundreds of volts in nanoseconds. The newer opto-isolators can give a pulse rise time of a few nanoseconds, with output compatible with MOSFET devices, in which delays are reduced to nanoseconds. Integrated DC/DCconverters are now available. Using these new resources we developed a new electric (more) al stimulus isolator circuit with selectable constant-current and constant-voltage modes, which are precise and easy to construct. The circuit works like a regulated power supply in both modes with output switched to zero or to free mode through an opto-isolator device. The isolator analyses showed good practical performance. The output to ground resistance was 1011 ohms and capacitance 35 picofarads. The rise time and fall time were identical (5 µs) and constant. The selectable voltage or current output mode made it very convenient to use. The current mode, with higher output resistance values in low current ranges, permits intracellular stimulation even with tip resistances close to 100 megaohms. The high compliance of 200 V guarantees the value of the current stimulus. The very low output resistance in the voltage mode made the device highly suitable for extracellular stimulation with low impedance electrodes. Most importantly, these characteristics were achieved with a circuit that was easy to build and modify and assembled with components available in Brazil.
Thin-film ferromagnetic inductors show great potential as the energy storage element for integrated circuits containing on-chip power management. In order to achieve the high energy storage required for power management, on-chip inductors require relatively thick magnetic yoke materials (several microns or more), which can be readily deposited by electroplating through a photoresist mask as demonstrated in this paper, the yoke material of choice being Ni45Fe55, whose properties of relatively high moment and electrical resistivity make it an attractive model yoke material for inductors. Inductors were designed with a variety of yoke geometries, and included both single-turn and multi-turn coil designs, which were fabricated on 200 mm silicon wafers in a CMOS back-end-of-line (BEOL) facility. Each inductor consisted of electroplated copper coils enclosed by the electroplated Ni45Fe55 yokes; aspects of the fabrication of the inductors are discussed. Magnetic properties of the electroplated yoke materials are described, including high frequency permeability measurements. The inductance of 2-turn coil inductors, for example, was enhanced up to about 6 times over the air core equivalent, with an inductance density of 130 nH/mm2 being achieved. The resistance of these non-laminated inductors was relatively large at high frequency due to magnetic and eddy current losses but is expected to improve as the yoke material/structure is further optimized, making electroplated yoke-containing inductors attractive for dc-dc power converters.
A simple numerical simulation of current flowing through electronic devices was examined for a hybrid power supply system composed of a DMFC and a capacitor connected in parallel. The simulation was investigated by representing a combination of ohmic resistance, charge transfer reaction resistance, mass transfer resistance and double layer capacitance of a DMFC as a simple ideal resistor, based on measured data when DMFC was generating electricity. The simulation result was found to agree with experimental measured current flowing through the DMFC and the capacitor, although a slight disagreement was observed because of the presence of ohmic resistance between circuit components. The simulation of DMFC-capacitor hybrid power supply system indicated the importance of the inner resistance of the capacitor. The hybrid simulation was also applied to a system assumed to consist of ?DMFC and micro electrochemical capacitor (MECC) system. The effect of applying a DC-DCconverter to the system was indicated. The simulation allows to predict the degree of improvement required without performing actual fabrication of ?DMFC and MECC.
A maximum power point tracker MPPT for photovoltaic systems is presented. The equipment can output up to 600 W and its control signals are generated by a PIC microcontroller. The principle of control is based on current and voltage sampling at the output terminals of the photovoltaic generator. From power comparison of two consecutive samples, it is possible to know how far from the optimal point the system is working. Output voltage control is used to force the system to work within the optimal area of operation. The microcontroller program sequence, the DC/DCconverter structure and the most relevant results are shown. [Spanish] En este trabajo se presenta el desarrollo de un controlador de potencia maxima para su aplicacion en sistemas fotovoltaicos (SFVs). El diseno alcanza una potencia de 600 W y sus senales de control son generadas con un controlador PIC. El principio de control se basa en el muestreo de la corriente y la tension en las terminadas del generador fotovoltaico GFV. De dos muestreos consecutivos, y por comparacion de las potencias, se determina que tan alejado del punto optimo opera el sistema. La operacion del sistema dentro de la zona de funcionamiento optimo se asegura mediante un control por tension. Se muestra la secuencia de programacion del microcontrolador, la estructura del convertidor CD/CD empleado y algunos resultados relevantes.
The introduction of Distributed Flexible Network Photovoltaic (DFNPV) system is going towards solving the shortcomings of stand-alone systems in remote areas. Three types of configurations of DFNPV system are studied: star, loop, and mesh. Each configuration has many subsystems, which are assumed to have the similar characteristics and location, and consist of PV panel, DC/DCconverter, and dc load.Comparative study had been carried out from the viewpoint of power losses in wires, wire length, and initial cost. First of all for estimating the size of DFNPV system within acceptable voltage drop, relations between wire length, power loss, wire cost, and cable types are discussed. The problem in DFNPV System is to find the best location of the battery bank from a many viewpoints, minimum extension cost and minimum losses in wires. This paper describes how to optimize the best location of the common battery bank from the viewpoints of the cost of power losses and the extension cost. The results of optimizing configurations show that a star configuration for initial installations is most effective, in future expansion; loop network is more cost effective. In addition, the economic study shows the final cost advantage of DFNPV system, for three types of configurations over stand-alone ones.
This paper presents an inductorless cascaded H- bridge multilevel boost inverter for EV and HEV applications. Currently available power inverter systems for HEVs use a DC- DC boost converter to boost the battery voltage for a traditional 3-phase inverter. The present HEV traction drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. An inductorless cascaded H-bridge multilevel boost inverter for EV and HEV applications is proposed in this paper. Traditionally, each H-bridge needs a DC power supply. The proposed inductorless cascaded H-bridge multilevel boost inverter uses a standard 3-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg which uses a capacitor as the DC power source. Fundamental switching scheme is used to do modulation control and to produce a 5-level phase voltage. Experiments show that the proposed inductorless DC-AC cascaded H-bridge multilevel boost inverter can output a boosted AC voltage.
This paper presents a cascaded H-bridge multilevel boost inverter for electric vehicle (EV) and hybrid EV (HEV) applications implemented without the use of inductors. Currently available power inverter systems for HEVs use a dc-dc boost converter to boost the battery voltage for a traditional three-phase inverter. The present HEV traction drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. A cascaded H-bridge multilevel boost inverter design for EV and HEV applications implemented without the use of inductors is proposed in this paper. Traditionally, each H-bridge needs a dc power supply. The proposed design uses a standard three-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg which uses a capacitor as the dc power source. A fundamental switching scheme is used to do modulation control and to produce a five-level phase voltage. Experiments show that the proposed dc-ac cascaded H-bridge multilevel boost inverter can output a boosted ac voltage without the use of inductors.
In this study, we investigated the capability of harvesting the electrical energy from mechanical vibrations in a dynamic environment through a “cymbal” piezoelectric transducer. Targeted mechanical vibrations lie in the range of 50–150 Hz with force amplitude in the order of 1 kN (automobile engine vibration level). It was found that under such severe stress conditions the metal–ceramic composite transducer “cymbal” is a promising structure. The metal cap enhances the endurance of the ceramic to sustain high loads along with stress amplification. In this preliminary study, the experiments were performed at the frequency of 100 Hz on a cymbal with 29 mm diameter and 1 mm thickness under a force of 7.8 N. At this frequency and force level, 39 mW power was generated from a cymbal measured across a 400 k? resistor. A DC–DCconverter was designed which allowed the transfer of 30 mW power to a low impedance load of 5 k? with a 2% duty cycle and at a switching frequency of 1 kHz.
The III-V nitrides have proved to be good materials for optoelectronic and electronic devices due to their large bandgaps, high breakdown voltages, and high carrier velocities. To further improve the device performance for outdoor lighting and wireless communication, it is essential that ohmic contacts with very low contact resistance be developed. The selective area growth (SAG) utilizing tunneling effect has been the most promising approach to obtaining the desired low resistance. However, there have been a number of problems, such as the desorption of GaN and diffusion of dopants. The main objective of this research is to investigate and develop stable and reproducible low ohmic contacts through careful monitoring of the GaN surface and distribution of dopants while employing SAG by plasma assisted molecular beam epitaxy (PAMBE). The work specifically involved thin film growth, film characterization, device fabrication and device characterization. To develop the SAG technique and study the effect of etchants on single crystal GaN layers during ohmic contact fabrication, surface bonding and surface morphology were examined. Another important phase of this work consisted of achieving the ohmic contact and device performance enhancement with SAG process and interface analysis by cross sectional TEM. The SAG technique was expanded to nonalloyed ohmic contacts proving that the SAG is crucial in fabrication of nonalloyed ohmic contacts. Finally, high electron mobility transistors (HEMTs) were demonstrated for a realistic DC-DC (direct current) converter.
This paper describes the operating characteristics of a stabilizing circuit using commercial electricity, those of a stabilizing circuit using solar cells, relation between the quantity of solar radiation and the maximum output of a semiconductor laser diode (LD), and simulation results of annual LD output in Sendai City. The stabilizing circuit for the solar-cell driven LD was structured such that the output of the solar cell panels was guided to a DC/DCconverter, that the voltage was set at a prescribed value and that the current was stabilized with the use of power MOSFET. The solar cells used in the experiment were monocrystal silicone solar cells with the maximum output of 53W each. In the experiment, the LD was protected by stabilizing the current at a set value when an excess current was supplied to the stabilizing circuit. As a result of the simulation of the annual LD output from the meteorological data of Sendai City, it was predicted that a solar cell of approximately 1kW was able to provide an annual output of 102MJ and that the efficiency was highest with four sheets of the solar cell. Consequently, consistency proved to be essential between the LD and the solar cell output. 3 refs., 7 figs.
Electronic circuits and systems designed for deep space missions need to operate reliably and efficiently in harsh environments that include very low temperatures. Spacecraft that operate in such cold environments carry a large number of heaters so that the ambient temperature for the onboard electronics remains near 20 C. Electronics that can operate at cryogenic temperatures will simplify system design and reduce system size and weight by eliminating the heaters and their associated structures. As a result, system development and launch cost will be reduced. At the NASA Glenn Research Center, an ongoing program is focusing on the development of power electronics geared for deep space low-temperature environments. The research and development efforts include electrical components design, circuit design and construction, and system integration and demonstration at cryogenic temperatures. Investigations are being carried out on circuits and systems that are targeted for use in NASA missions where low temperatures will be encountered: devices such as ceramic and tantalum capacitors, metal film resistors, semiconductor switches, magnetics, and integrated circuits including dc/dcconverters, operational amplifiers, voltage references, and motor controllers. Test activities cover a wide range of device and circuit performance under simple as well as complex test conditions, such as multistress and thermal cycling. The effect of low-temperature conditions on the switching characteristics of an advanced silicon-on-insulator field effect transistor is shown. For gate voltages (VGS) below 2.6 V, drain currents at -190 C are lower than drain currents at room temperature (20 C).
Power electronic circuits and systems designed for deep space applications and outer planetary exploration are required to operate reliably and efficiently under extreme temperature conditions. This requirement is dictated by the fact that the operational environments associated with some of the space missions would encompass temperatures as low as -183 C. The development and utilization of electronics capable of low temperature operation would not only fulfill the advanced technology requirements, but also would contribute to improving circuit performance, increasing system efficiency, and reducing development and launch costs. These benefits are generally achieved by the improved intrinsic properties of some of the electronic materials at low temperature, reduced device losses, and the elimination of heating elements used in conventional systems at low temperatures. Power electronic circuits are widely used in space power systems in the areas of power management, conditioning, and control. In this work, the performance of certain power electronic components and systems was investigated under low temperature. These include inductors, capacitors, pulse-width-modulation (PWM) controllers, and advanced commercial DC/DCconverter modules. Different properties were determined as a function of temperature in the range of 20 C to -140 C, at various current and voltages levels. The experimental procedures along with the experimental data obtained are presented and discussed in this paper.
Radioactive materials make up a significant part of the hazardous-material inventory of the United States Department of Energy. Much of the radioactive material will be inspected or handled by robotic systems that contain electronic circuits that may be damaged by gamma radiation and other particles emitted from radioactive material. To use a mobile robot in the vicinity of high-level gamma radiation requires a special design. Since materials and electronic circuits can withstand some radiation without failure, the simplest approach would be simply to use an unmodified commercial mobile robot in the radioactive environment but remove it before failure occurs. Unpowered backup is another method of extending system lifetime in an ionizing radiation environment. When the primary system fails or degrades sufficiently, the backup system can be switched in to maintain system operation. By careful design and production-lot testing, systems can be designed to meet moderate doses of radiation; however, randomly-selected off- the-shelf commercial parts cannot be guaranteed to meet a specified total-dose tolerance. We can define the Basic Radiation-Hardened System to be a teleoperated K3A transport capable of deploying a radiation-hardened video camera for initial entry and inspection applications. The electronics in the K3A mobile base has three essential modules: MA-2 Motor Amplifier Circuit, DC-I Drive Control Computer, and DC/DCConverter for powering the electronics. Design of the system will be discussed.
This paper presents the introduction of problem-based learning (PBL) in a power electronics course at the University of Oviedo, Gijon, Spain, by means of two practical projects: the design and construction of a switching-mode power supply (SMPS) prototype and the static study of a dc-dcconverter topology. The goal of this innovation was for students to apply in practice the knowledge they had acquired in theory classes. PBL is known to be a motivating, problem-centered teaching method that brings the real professional world closer to the student. The instructors thus considered PBL to be the most suitable methodology to obtain the desired results. The underlying methodology, task planning, and assessment of these projects will be presented. Furthermore, the influence of the introduction of PBL in practical sessions versus the traditional teaching method will be discussed. Finally, the instructors' reflections and conclusions regarding the application of PBL in this course from 2007-2009 will be presented. (Contains 1 table and 5 figures.)
Description of how to make PV modules so that they are less likely to turn into safety hazards. Making modules inherently safer with minimum additional cost is the preferred approach for PV. Safety starts with module design to ensure redundancy within the electrical circuitry to minimize open circuits and proper mounting instructions to prevent installation related ground faults. Module manufacturers must control the raw materials and processes to ensure that that every module is built like those qualified through the safety tests. This is the reason behind the QA task force effort to develop a 'Guideline for PV Module Manufacturing QA'. Periodic accelerated stress testing of production products is critical to validate the safety of the product. Combining safer PV modules with better systems designs is the ultimate goal. This should be especially true for PV arrays on buildings. Use of lower voltage dc circuits - AC modules, DC-DCconverters. Use of arc detectors and interrupters to detect arcs and open the circuits to extinguish the arcs.
The core of any electric vehicle (EV) is the electric drive train, intended as the energy conversion chain from the energy tank (typically some kind of rechargeable battery) to the electric motor that converts the electrical energy into the mechanical energy needed for the vehicle motion. The need for on-board electrical energy storage is the factor that has so far prevented pure electric vehicles from conquering significant market share. In fact electrochemical batteries, which are currently the most suitable device for electrical energy storage, have serious limitations in terms of energy and/or power density, cost and safety. All those characteristics reflect in pure electric vehicles being outperformed by standard internal combustion engine (ICE) based vehicles in terms of driving range, time needed to refuel and purchase cost. Electric vehicles do have their distinctive advantages, being intrinsically much more efficient, operating at zero emissions at the pipe, and offering a higher degree of controllability that can potentially enhance driving safety. No wonder then, that electric energy storage technology has attracted considerable R&D investments, resulting in new traction battery packs that are getting closer and closer to the industrial targets. In this scenario of EV technology gaining momentum, power electronics engineers have to come up with newer solutions allowing for more efficient and more reliable utilization of the precious on-board energy that comes in a form that cannot be directly utilized by the motor. At present, most of the research in the area of power electronics for automotive is focused in volume and cost reduction techniques. The increase in power density is pursued by developing components that can be operated at higher temperature, thus relieving the requirements on cooling. In this thesis, the focus is on the development of alternative topologies for the power electronics converters that make use of some peculiarities of the energy storage components and of the electrical drive train in general, rather than being a mere component-level optimization of well established topologies. A novel converter topology is proposed for hybridization of the energy source with a supercapacitor-based power buffer being used to assist the main traction battery. From the functional point of view, the topology implements a bidirectional DC/DCconverter. Making use of the fact that the battery terminal voltage is close to constant, an arrangement for the supercapacitors is devised allowing for bidirectional power flow by using power electronics devices of lower ratings than the ones needed in conventional DC/DCconverters. At the same time, much smaller magnetic components are needed. Theoretical analysis of the operation of the proposed converter is given, allowing for optimized design. A full-scale experimental prototype rated at 30 kW, intended for use in a pure EV, has been built and tested. Results validate the theory and show that no particular impediment exist to the deployment of the concept in practical applications. Another concept introduced in the thesis is an architecture where the traction inverter is embedded in the energy storage device. The latter is constituted by several modules, as in the case of modern Li-ion battery systems, and each module is equipped with a local power electronics interface, making it functionally equivalent to a controllable voltage source. The result is a modular, distributed system that can be engineered to have very high reliability and also to exhibit self-healing properties. A prototype with a minimum number of modules has been built and tested. Results confirm the effectiveness of the system, and make it a good candidate for deployment in applications where reliability is the most important requirement. (Author). 107 refs., 93 figs., 16 tabs
Conventional (type-1) fuzzy logic controllers have been commonly used in various power converter applications. Generally, in these controllers, the experience and knowledge of human experts are needed to decide parameters associated with the rule base and membership functions. The rule base and the membership function parameters may often mean different things to different experts. This may cause rule uncertainty problems. Consequently, the performance of the controlled system, which is controlled with type-1 fuzzy logic controller, is undesirably affected. In this study, a type-2 fuzzy logic controller is proposed for the control of buck and boost DCâ??DC converters. To examine and analysis the effects of the proposed controller on the system performance, both converters are also controll...
The steady-state and transient performance of PM and series motors coupled to centrifugal pump supplied from Photovoltaic source through intermediate buck-boost converter is analyzed. The effect of duty ratio selection based on maximum power operation of PV source and maximum daily gross mechanical power is investigated on the solar cell array operating point, motor armature voltage, armature current and motor efficiency variation. Studies are carried out by formulating the mathematical models for photovoltaic source, DC motors, power converter and load. Starting torque variation, Torque magnification factors expressions are derived and their variations plotted for the above two cases. Simulation software is developed for the transient and steady-state analysis of PV supplied DC motors for different duty ratios of power converter and solar insolations. Steady-state and transient performance characteristics are presented. The performance of PM DC motor is compared with the series motor operating under identical conditions.
This paper deals with three-phase matrix-reactance frequency converters (MRFCs). Their topologies are based on unipolar PWM AC matrix-reactance choppers (MRCs). In the discussed MRFCs the voltage matrix converter (MC) or current MC is used for electrical energy transfer instead of the source or load synchronous connected switches. As a result both a frequency change and the buck-boost voltage conversion are possible. It is important that electrical energy storage in the passive elements used in MRFCs is equal to zero in an AC voltage period; therefore these converters can be treated as ones without DC storage. The main purpose of this paper is to carry out a comprehensive comparison of basic properties of MRFCs using an low frequency (LF) transfer matrix modulation method, which are the FC...
The present contribution describes the CuK-converter. It is a bi-directional, high and low-changing DC-to-DC converter. It distinguishes itself by its design but it is not easy to control. A condition control system has been developed with various tools and a mathematical description of the converter (State-space averaging). It was proved that different tools (SIMPLORER, PSPICE, Matlab, C) and methods (discrete simulation, State-space averaging) support the design of the control system. The results were verified by comparative calculations (simulations). This is important, because the results of a simulation should always be tested for being plausible in order to avoid adjustment mistakes of the program or false modelling. Even though individual simulation tools have specific advantage, their functions resemble each other more and more due to very fast engineering. Hence it depends on the subjective criteria of the user, which simulation tool is used for a certain problem, e.g. if he knows the program or if a simple, almost intuitive handling is possible. (orig.) [German] Im vorliegenden Beitrag wurde der Cuk-Wandler vorgestellt. Es ist ein bidirektionaler, hoch- u. tiefsetzender DC/DC-Wandler. Er besticht durch seinen einfachen Aufbau, ist aber dennoch nicht einfach zu regeln. Mit verschiedenen Werkzeugen und einer mathematischen Beschreibung des Wandlers (State-space averaging) wurde eine Zustandsregelung entwickelt. Gezeigt wurde, dass verschiedene Werkzeuge (SIMPLORER, PSPICE, Matlab, C) und Methoden (diskrete Simulation, State-space averaging) den Reglerentwurf unterstuetzen. Dabei wurden die Ergebnisse mit Vergleichsrechnungen (Simulationen) verifiziert. Dieses ist wichtig, da die Ergebnisse einer Simulation immer auf Plausibilitaet geprueft werden sollten, um Einstellungsfehler des Programms oder eine fehlerhafte Modellierung zu vermeiden. Obwohl die einzelnen Simulationstools ueber spezifische Vorteile verfuegen, ueberdecken sie sich aufgrund ihrer rasanten Entwicklung in der Funktionalitaet immer staerker. Welches Simulationstool daher fuer ein bestimmtes Problem eingesetzt wird, haengt stark von subjektiven Kriterien des Benutzers ab, z.B. ob er das Programm kennt oder eine einfache, moeglichst intuitive Bedienung moeglich ist. (orig.)
Hybrid electric vehicles (HEVs) are driven by at least two prime energy sources, such as an internal combustion engine (ICE) and propulsion battery. For a series HEV configuration, the ICE drives only a generator, which maintains the state-of-charge (SOC) of propulsion and accessory batteries and drives the electric traction motor. For a parallel HEV configuration, the ICE is mechanically connected to directly drive the wheels as well as the generator, which likewise maintains the SOC of propulsion and accessory batteries and drives the electric traction motor. Today the prime energy source is an ICE; tomorrow it will very likely be a fuel cell (FC). Use of the FC eliminates a direct drive capability accentuating the importance of the battery charge and discharge systems. In both systems, the electric traction motor may use the voltage directly from the batteries or from a boost converter that raises the voltage. If low battery voltage is used directly, some special control circuitry, such as dual mode inverter control (DMIC) which adds a small cost, is necessary to drive the electric motor above base speed. If high voltage is chosen for more efficient motor operation or for high speed operation, the propulsion battery voltage must be raised, which would require some type of two-quadrant bidirectional chopper with an additional cost. Two common direct current (dc)-to-dc converters are: (1) the transformer-based boost or buckconverter, which inverts a dc voltage, feeds the resulting alternating current (ac) into a transformer to raise or lower the voltage, and rectifies it to complete the conversion; and (2) the inductor-based switch mode boost or buckconverter [1]. The switch-mode boost and buck features are discussed in this report as they operate in a bi-directional chopper. A benefit of the transformer-based boost converter is that it isolates the high voltage from the low voltage. Usually the transformer is large, further increasing the cost. A useful feature of the switch mode boost converter is its simplicity. Its inductor must handle the entire current, which is responsible for its main cost. The new Z-source inverter technology [2,3] boosts voltage directly by actively using the zero state time to boost the voltage. In the traditional pulse width modulated (PWM) inverter, this time is used only to control the average voltage by disconnecting the supply voltage from the motor. The purpose of this study is to examine the Z-source's potential for reducing the cost and improving the reliability of HEVs.
The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into the specifications. Based on these two documents, a set of 23 topologies was analysed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies are in this report further investigated by means of an initial design-iteration and simulations. The items of interest in this report are efficiency and component ratings (magnetics, transistors, diodes and capacitors). The simulations reveal that DC-to-DC converters (for amplifying the PV-Module voltage) build on resonant technology (series-resonant and parallel-resonant) all suffers from high circulating currents inside the resonant tank; qua a low efficiency is the result. Whereas, the standard full-bridge converter and the novel MOHAN converter do not suffers from these severe currents, which also reflects into a higher efficiency. The ratings for the resonant converters are also somewhat larger than for the two other solutions. The two selected DC/DCconverters are, on the basis of these properties, the standard full-bridge converter and the MOHAN converter. The simulated DC-to-AC inverters (for modulating the sinusoidal grid current) both show excellent performance in terms of high efficiency and low ratings. However, it seems that the MOSFET equipped inverters has lower losses than the IGBT equipped one. The last inverter investigated is the novel Dual FlyBack Inverter, which both amplifies the PV-Module voltage and modulates the sinusoidal grid current in one single process. Unfortunately, this circuit suffers from a low efficiency due to a high internal current. However, the efficiency is expected to increase with an increasing switching frequency, so the inverter is also selected for further design. A novel 'single-step' solution emerged at the end of the period: the SHIMIZU topology. However, this solution is not simulated in this report, but it is believed to be high effective in terms of efficiency and ratings. (au)
This paper describes analyses using a status space method to verify fundamental characteristics of a three-phase step-up/down current-source rectifier. The analytical results were compared with experimental results to clarify the practicability of the circuitry. The circuitry used insulated-gate bipolar transistors (IGBT) as switching elements, and the DC circuit had buck boost converters and buckconverters connected longitudinally and used a PWM method. A simulation revealed that current flowing in the fly-back inductor is kept nearly constant, and the source current is controlled sinusoidally. The result of experiments on a circuit fabricated practically using IGBT showed a good agreement with the simulation result including from ripples to transient phenomena attributable to switching the self arc-extinguishing elements. It was found that low-order harmonics in the measurements and calculations have been suppressed to approximately 1% or lower. Measurements and theoretical values agreed approximately well with each other in static characteristics when modulation rates were varied, verifying that the step-up and down characteristics can be obtained as proposed in the circuitry. 8 refs., 9 figs.
This paper is aimed to develop a digital signal processor (DSP) for controlling a solar cell and wind-turbine hybrid charging system. The DSP consists of solar cells, a wind turbine, a lead acid battery, and a buck-boost converter. The solar cells and wind turbine serve as the system's main power sources and the battery as an energy storage element. The output powers of solar cells and wind turbine have large fluctuations with the weather and climate conditions. These unstable powers can be adjusted by a buck-boost converter and thus the most suitable output powers can be obtained. This study designs a booster by using a dsPIC30F4011 digital signal controller as a core processor. The DSP is controlled by the perturbation and observation methods to obtain an effective energy circuit with a full 100 W charging system. Also, this DSP can, day and night, be easily controlled and charged by a simple program, which can change the state of the system to reach a flexible application based on the reading weather conditions.
Half-bridge inverters, full-bridge inverters and bidirectional buckconverters share a common topological structure, in which two switches and two diodes are present. In such a topology, a dead time between the two signals controlling the switches is inserted. This influences the relationship between output voltage, input voltage and duty cycle as a function of the output current. In the literature, the dead-time effect has been studied in relation with inverters, active filters, voltage regulated modules and high-precision power amplifiers, and dead-time compensation techniques have been proposed. However, the measurement of the current is normally required for all dead-time compensation strategies, which can be a problem when the current approaches or crosses zero. In this paper, the operation of a bidirectional buckconverter in the region around zero current has been analytically analyzed. It has been shown that in a region around zero there is no dead-time effect. The analytical expression of the bordersbetween the areas where the dead-time effect is positive, zero or negative has been given. Moreover it has been shown that between these three areas, there are four other transitional areas. The analytical analysis has been confirmed by simulation and experimental results.
Phase 1 was a concept definition effort to extend space-type dc/dcconverter technology to the megawatt level with a weight of less than 0.1 kg/kW (220 lb./MW). Two system designs were evaluated in Phase 1. Each design operates from a 5 kV stacked fuel cell source and provides a voltage step-up to 100 kV at 10 A for charging capacitors (100 pps at a duty cycle of 17 min on, 17 min off). Both designs use an MCT-based, full-bridge inverter, gaseous hydrogen cooling, and crowbar fault protection. The GE-CRD system uses an advanced high-voltage transformer/rectifier filter is series with a resonant tank circuit, driven by an inverter operating at 20 to 50 kHz. Output voltage is controlled through frequency and phase shift control. Fast transient response and stability is ensured via optimal control. Super-resonant operation employing MCTs provides the advantages of lossless snubbing, no turn-on switching loss, use of medium-speed diodes, and intrinsic current limiting under load-fault conditions. Estimated weight of the GE-CRD system is 88 kg (1.5 cu ft.). Efficiency of 94.4 percent and total system loss is 55.711 kW operating at 1 MW load power. The Maxwell system is based on a resonance transformer approach using a cascade of five LC resonant sections at 100 kHz. The 5 kV bus is converted to a square wave, stepped-up to a 100 kV sine wave by the LC sections, rectified, and filtered. Output voltage is controlled with a special series regulator circuit. Estimated weight of the Maxwell system is 83.8 kg (4.0 cu ft.). Efficiency is 87.2 percent and total system loss is 146.411 kW operating at 1 MW load power.
The PHOTONERGY project (the former SolcelleInverter project) was initiated on the 1st of September 2001, with a state-of-the-art analysis, which concluded into specifications. Based on this 23 topologies were analyzed in for efficiencies. The results from this analysis was five candidates which all showed a somewhat good efficiency. These five topologies were in further investigated by means of an initial design-iteration and simulations. Two different solutions were picked up in due to their high efficiency and low cost. 1. The standard full-bridge phase shifted DC/DCconverter together with a standard DC/AC inverter, 2. A modified version of the novel Shimizu topology. A patent is pending on this modified version. These two inverters are in this document developed and made ready for prototyping. This includes design and selection of reactive- and switching-components, e.g. filter- and bulk-capacitors, low- and high-frequency inductors, high frequency transformers, MOSFETs and diodes. The design of auxiliary circuits is also included, e.g. gate drivers for the MOSFETs, measuring circuits for the grid-current and -voltage, PV-module-current and voltage, protection circuits, hardware near controllers and finally a switch mode power supply. However, the design of the various controllers, except the hardware near PV-current controller for the full bridge phase shifted converter, is not documented in this report but will come later on. This includes all controllers, e.g. maximum power point tracking for the PV-module, utility grid current controller, DC-link voltage controller, phase locked loops, and detection of islanding operation. All of these control loops are to be implemented in a micro-controller. (au)
A soft switching two-switch forward converter is presented to achieve zero voltage switching (ZVS) turn-on of switching devices. In the adopted converter, a buck-boost type of active clamp is connected in parallel with the primary winding of transformer. The energy stored in the transformer leakage inductance and magnetizing inductance can be recovered so that the peak voltage stress of switching devices is limited. The resonance between the transient interval of two main and auxiliary switches is used to achieve ZVS turn-on of all switches. The current doubler synchronous rectifier is used in the secondary side of transformer for reducing the root mean square value of output inductor current, transformer secondary winding current and output voltage ripple by cancelling the current ripple ...
In most cases, PWM power factor corrected (PFC) converters are constructed by a diode rectifier and an active power circuit such as a boost or buck-boost chopper. Besides the PFC operation, the active power circuit can control the dc output voltage. The output voltage of the PAM inverters are controlled by varying the level of dc input voltage. A PAM method reduces the voltage and current stresses of the inverter and motors. This paper proposes a new PAM inverter system with high power factor converter to obtain a sinusoidal input current. A Proposed PAM method to reduce the torque ripple in the induction motor can be reduced a switching losses by providing a pausing interval where the switching operation stops during a part of one period. 8 refs., 15 figs., 1 tab.
We derived a second-order S-switching iterative map describing the dynamics of simple feedback Buck switching regulator operating in continuous mode. Analysis of this map shows that chaos and bifurcations may occur along with the changing of values of some system parameters. By making the converter operating in chaos, the simulation results demonstrate that a reduction of spectral peak and consequent spreading of the spectrum can be shown, any desirable amount of reduction and consequent spreading of the spectrum can be obtained simply by varying the control parameter of the circuit and a optimization of system bifurcation parameters is designed to obtain better performances of the converter on electromagnetic compatibility (EMC). Moreover this will hardly influence to output voltage ripples.
Accurate identification of parasitic parameters on a printed circuit board (PCB) and establishment of an effective design method by considering the parasitic components in a power electronics circuit will become major technological issues to increase the power density of power converters. This study focuses on time domain reflectometry (TDR) method in order to identify and to measure the value of parasitic elements on the PCB in which circuit components are closely mounted. A printed circuit board for high power density converter can be effectively designed by using measured value of parasitic parameters. In this paper, two-step measuring method of measuring multiple parasitic inductances of those existing on a buck chopper PCB is proposed. In this method, a discrimination of the location of parasitic elements is identified on the first step, and the values of each parasitic component are measured on the second step. The accuracy of the measured parasitic inductances is verified through the comparison of experimental and simulation results.
Abstract in english This paper presents the integrated design and control of a buck boost converter (BBC). In the proposed methodology the design tool provides simultaneously the controller tuning and BBC design parameters in such a way that some closed-loop pre-specified static and dynamic behavior is obtained. This approach contrasts with the traditional methodology, where the design of BBC is performed without taking into account its dynamical behavior. An optimization procedure is used t (more) o obtain the electronic components of the BBC and the tuning parameters of the controller, minimizing an objective function that considers the set of performance specifications. Although the methodology can be applied to any converter and any control strategy, in this particular case an ideal BBC and a Sliding Model Control (SMC) strategy are used. Some simulation results show the advantages and principally the flexibility that can be obtained with this approach.
Fuel cells represent an important potential alternative to conventional thermal-mechanical- electrical energy transformations due to their highly efficient direct conversion of chemical energy, i.e. hydrogen or natural gas into electrical energy. Inverter systems that feed electrical power from fuel cells into the grid must convert the direct current of the fuel cell into the alternating current of the grid. In addition, these inverters have to adapt the different voltages of the fuel cell system to the grid. Inverter systems for fuel cells can be seen as an own field of research. Only a few results from other fields of research in power electronic circuits in the medium power range - like converters for electrical drives or power supplies - can be applied to inverter systems for fuel cells due to the different technical constraints. In this thesis, different topologies of appropriate inverter systems in the medium power range of 20 kW and higher are analyzed and compared to each other. This study includes transformerless inverters as well as two-stage inverter systems with high frequency transformers (DC/DCconverter combined with an inverter). In the beginning, this thesis shows the electrical characteristics of the fuel cell and of the main inverter components like power semiconductors and passive components. In addition, the principles of power semiconductor losses and methods of the semiconductor power loss calculation are shown. This work does not focus on the dimensioning of the passive components like capacitors, chokes and transformers. The main principles of the dimensioning of the passive components are shown but are not analyzed in detail. The summary of the demands of a fuel cell inverter system is followed by the analytical analysis of the different inverter topologies. In addition, the semiconductor loss calculations for the topologies will be derived. To gain practical experience and to verify parts of the theoretical analysis, the converters presented were built and tested in the laboratory. The characteristics of their laboratory performance are shown. Some details of the topologies could only be seen by looking at the experimental results as the semiconductor commutation behavior for example. Finally, the inverter topologies are analyzed regarding their suitability as inverter system for feeding electrical energy from fuel cells to the grid. This analysis takes the electrical characteristics of a fuel cell system into account. It is based on the inverters operating behavior, their semiconductor power rating, the inverter efficiency and experimental results from laboratory setups of the converters. The semiconductor power rating and efficiency are compared based on an analytical calculation of the semiconductor losses.
Interviewee: Paul Lombardo DNAi Location:Chronicle>Trial of Carrie Buck>players The only photograph of Carrie Buck with her mother Emma, taken the day before she would stand trial before the collective onslaught of the American eugenics movement.
Power conversion systems often require a dc voltage which must be derived from the AC mains voltage. The simplest approach, using a diode rectifier and a capacitive filter results in high input harmonic distortion and a load dependent power factor. The concept of ripple steering with a coupled inductor as used in DC/DC power conversion is extended to include AC systems. A model for coupled inductor capacitor filters for improvement of filtering in DC/DC conversion circuits is equally applicable for circuits containing AC quantities. A mathematical model of the coupled inductor shows improved results over a conventional LC input filler. 9 figs., 10 refs.
Abstract in spanish En este artículo se describe el diseño, modelado e implementación de un inversor monofásico conectado a la red a partir de fuentes renovables de energía. Se estudia el modelo en pequeña señal del convertidor para a continuación diseñar los lazos de control del mismo. Con el fin de controlar la inyección de energía a la red proveniente de la renovable, se propone utilizar un control de corriente media (ACC). Los controladores son obtenidos a través del análisi (more) s aplicado sobre el modelo en pequeña señal obtenido a partir del modelo del conmutador PWM y de la aproximación del inversor a un convertidor Buck. Finalmente se realizan simulaciones y pruebas experimentales con el fin de validar la respuesta transitoria y en estado estable del inversor. Abstract in english This paper describes the design, modeling and implementation of a single-phase inverter connected to the grid from renewable energy sources. We study the model in small signal to be below the control loops design it. In order to control the injection of energy into the grid from renewable is proposed for average current control (ACC). Drivers are obtained through the analysis applied to the small signal model obtained from the PWM switch model and the approach of the inve (more) stor to a Buckconverter. Finally, simulations and experimental tests conducted to validate the transient response and steady-state investor.
Topics covered include: Wind and Temperature Spectrometry of the Upper Atmosphere in Low-Earth Orbit; Health Monitor for Multitasking, Safety-Critical, Real-Time Software; Stereo Imaging Miniature Endoscope; Early Oscillation Detection Technique for Hybrid DC/DCConverters; Parallel Wavefront Analysis for a 4D Interferometer; Schottky Heterodyne Receivers With Full Waveguide Bandwidth; Carbon Nanofiber-Based, High-Frequency, High-Q, Miniaturized Mechanical Resonators; Ultracapacitor-Based Uninterrupted Power Supply System; Coaxial Cables for Martian Extreme Temperature Environments; Using Spare Logic Resources To Create Dynamic Test Points; Autonomous Coordination of Science Observations Using Multiple Spacecraft; Autonomous Phase Retrieval Calibration; EOS MLS Level 1B Data Processing Software, Version 3; Cassini Tour Atlas Automated Generation; Software Development Standard Processes (SDSP); Graphite Composite Panel Polishing Fixture; Material Gradients in Oxygen System Components Improve Safety; Ridge Waveguide Structures in Magnesium-Doped Lithium Niobate; Modifying Matrix Materials to Increase Wetting and Adhesion; Lightweight Magnetic Cooler With a Reversible Circulator; The Invasive Species Forecasting System; Method for Cleanly and Precisely Breaking Off a Rock Core Using a Radial Compressive Force; Praying Mantis Bending Core Breakoff and Retention Mechanism; Scoring Dawg Core Breakoff and Retention Mechanism; Rolling-Tooth Core Breakoff and Retention Mechanism; Vibration Isolation and Stabilization System for Spacecraft Exercise Treadmill Devices; Microgravity-Enhanced Stem Cell Selection; Diagnosis and Treatment of Neurological Disorders by Millimeter-Wave Stimulation; Passive Vaporizing Heat Sink; Remote Sensing and Quantization of Analog Sensors; Phase Retrieval for Radio Telescope and Antenna Control; Helium-Cooled Black Shroud for Subscale Cryogenic Testing; Receive Mode Analysis and Design of Microstrip Reflectarrays; and Chance-Constrained Guidance With Non-Convex Constraints.
Many small wind turbine generators (10 kW or less) consist of a variable speed rotor driving a permanent magnet synchronous generator (alternator). One application of such wind turbines is battery charging, in which the generator is connected through a rectifier to a battery bank. The wind turbine electrical interface is essentially the same whether the turbine is part of a remote power supply for telecommunications, a standalone residential power system, or a hybrid village power system, in short, any system in which the wind generator output is rectified and fed into a DC bus. Field experience with such applications has shown that both the peak power output and the total energy capture of the wind turbine often fall short of expectations based on rotor size and generator rating. In this paper, the authors present a simple analytical model of the typical wind generator battery charging system that allows one to calculate actual power curves if the generator and rotor properties are known. The model clearly illustrates how the load characteristics affect the generator output. In the second part of this paper, the authors present four approaches to maximizing energy capture from wind turbines in battery charging applications. The first of these is to determine the optimal battery bank voltage for a given WTG. The second consists of adding capacitors in series with the generator. The third approach is to place an optimizing DC/DC voltage converter between the rectifier and the battery bank. The fourth is a combination of the series capacitors and the optimizing voltage controller. They also discuss both the limitations and the potential performance gain associated with each of the four configurations.
The dissertation presents a new optimizing energy management concept for fuel cell-direct storage-hybrid systems. Initially, the characteristics of specific energy time series are investigated on the basis of real measurement data. A new concept for the multi-scale analysis, modelling and prediction of fluctuating photovoltaic supply and electric load demand profiles is developed. The second part of the dissertation starts with a discussion of the benefits of and the basic coupling and control principles for fuel cell-direct storage-hybrid systems. The typical characteristics of a PEM-fuel cell, a metal hydride hydrogen storage, a lithium-ion battery and a supercap unit are presented. A new modular DC/DC-converter is described. Results from experimental and theoretical investigations of the individual components and the overall hybrid system are discussed. New practicable models for the voltage-current-curve, the state of charge behaviour and the conversion losses are presented. The third part of the dissertation explains the new energy management concept. The optimization of power flows is achieved by a control-oriented approach, employing a) the primary control of bus voltage and fuel cell current, b) the secondary control to limit fuel cell current gradient and operating range and to perform direct storage charge control, and c) the system control to optimally adjust secondary control parameters aiming for a reduction of dynamic fuel cell stress and hydrogen consumption. Results from simulations and experimental investigations demonstrate the benefits and high capabilities of the new optimizing energy management concept. Examples of stationary and portable applications conclude the dissertation. (orig.)
The NASA Glenn Research Center, partner universities, and defense contractors are working to develop intelligent power management and distribution (PMAD) technologies for future spacecraft and launch vehicles. The goals are to provide higher performance (efficiency, transient response, and stability), higher fault tolerance, and higher reliability through the application of digital control and communication technologies. It is also expected that these technologies will eventually reduce the design, development, manufacturing, and integration costs for large, electrical power systems for space vehicles. The main focus of this research has been to incorporate digital control, communications, and intelligent algorithms into power electronic devices such as direct-current to direct-current (dc-dc) converters and protective switchgear. These technologies, in turn, will enable revolutionary changes in the way electrical power systems are designed, developed, configured, and integrated in aerospace vehicles and satellites. Initial successes in integrating modern, digital controllers have proven that transient response performance can be improved using advanced nonlinear control algorithms. One technology being developed includes the detection of "soft faults," those not typically covered by current systems in use today. Soft faults include arcing faults, corona discharge faults, and undetected leakage currents. Using digital control and advanced signal analysis algorithms, we have shown that it is possible to reliably detect arcing faults in high-voltage dc power distribution systems (see the preceding photograph). Another research effort has shown that low-level leakage faults and cable degradation can be detected by analyzing power system parameters over time. This additional fault detection capability will result in higher reliability for long-lived power systems such as reusable launch vehicles and space exploration missions.
The climatic and energy challenges were now clearly stated. The use of hydrogen is one of the best ways which gives many hopes. Fuel cells are an essential link in the chain of the use of hydrogen. Thus, a lot of studies have been undertaken throughout the world on fuel cells in many fields of physics. Concerning the field of power electronics, a lot of work on distributed generation technologies using fuel cells has been realised too and a great number of power converters dedicated to fuel cells have been studied. However, very few studies have been undertaken on the interactions between fuel cells and power converters. The goals of this work are to study interactions between fuel cells and power converters. Some requirements for the power electronic engineer can follow from this work. This work proposes high signal dynamic models of a H{sub 2}/O{sub 2} PEM fuel cell. These models include the different physical and chemical phenomena. Specific methods based on a limited number of original experiments (low frequency current sweeps) allow to extract the model parameters. These models are used to study the interactions between fuel cells and power converters which are the most used: buck chopper, boost chopper, inverters. The important part of the double layer capacitors has thus been underlined: they can filter the current harmonics created by the power converters. Finally, some choices of filtering elements to be connected to the fuel cell are proposed. (author)
This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can accurately produce the correct volt-sec average at its output, while simultaneously achieving inductive voltage boosting. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence no increase in switching losses. The proposed converter therefore offers a low cost alternative to sensitive applications that need to ride-through frequent input voltage sags. For confirming the converter performance, experimental testing using a constructed laboratory prototype is performed with its captured results presented in a later section of the paper.
DNAi location: Chronicle>Trial of Carrie Buck The 17 year-old protagonist of the Buck vs. Bell case, Carrie Buck, was pitted against an array of doctors, lawyers, and eugenicists who were intent on sterilizing her, including John Bell, the superintendent of the Virginia Colony for Epileptics and Feebleminded.
The Project Objective is to design innovative energy storage architecture and associated controls for high wind penetration to increase reliability and market acceptance of wind power. The project goals are to facilitate wind energy integration at different levels by design and control of suitable energy storage systems. The three levels of wind power system are: Balancing Control Center level, Wind Power Plant level, and Wind Power Generator level. Our scopes are to smooth the wind power fluctuation and also ensure adequate battery life. In the new hybrid energy storage system (HESS) design for wind power generation application, the boundary levels of the state of charge of the battery and that of the supercapacitor are used in the control strategy. In the controller, some logic gates are also used to control the operating time durations of the battery. The sizing method is based on the average fluctuation of wind profiles of a specific wind station. The calculated battery size is dependent on the size of the supercapacitor, state of charge of the supercapacitor and battery wear. To accommodate the wind power fluctuation, a hybrid energy storage system (HESS) consisting of battery energy system (BESS) and super-capacitor is adopted in this project. A probability-based power capacity specification approach for the BESS and super-capacitors is proposed. Through this method the capacities of BESS and super-capacitor are properly designed to combine the characteristics of high energy density of BESS and the characteristics of high power density of super-capacitor. It turns out that the super-capacitor within HESS deals with the high power fluctuations, which contributes to the extension of BESS lifetime, and the super-capacitor can handle the peaks in wind power fluctuations without the severe penalty of round trip losses associated with a BESS. The proposed approach has been verified based on the real wind data from an existing wind power plant in Iowa. An intelligent controller that increases battery life within hybrid energy storage systems for wind application was developed. Comprehensive studies have been conducted and simulation results are analyzed. A permanent magnet synchronous generator, coupled with a variable speed wind turbine, is connected to a power grid (14-bus system). A rectifier, a DC-DCconverter and an inverter are used to provide a complete model of the wind system. An Energy Storage System (ESS) is connected to a DC-link through a DC-DCconverter. An intelligent controller is applied to the DC-DCconverter to help the Voltage Source Inverter (VSI) to regulate output power and also to control the operation of the battery and supercapacitor. This ensures a longer life time for the batteries. The detailed model is simulated in PSCAD/EMTP. Additionally, economic analysis has been done for different methods that can reduce the wind power output fluctuation. These methods are, wind power curtailment, dumping loads, battery energy storage system and hybrid energy storage system. From the results, application of single advanced HESS can save more money for wind turbines owners. Generally the income would be the same for most of methods because the wind does not change and maximum power point tracking can be applied to most systems. On the other hand, the cost is the key point. For short term and small wind turbine, the BESS is the cheapest and applicable method while for large scale wind turbines and wind farms the application of advanced HESS would be the best method to reduce the power fluctuation. The key outcomes of this project include a new intelligent controller that can reduce energy exchanged between the battery and DC-link, reduce charging/discharging cycles, reduce depth of discharge and increase time interval between charge/discharge, and lower battery temperature. This improves the overall lifetime of battery energy storages. Additionally, a new design method based on probability help optimize the power capacity specification for BESS and super-capacitors. Recommendations include experimental implementation of the controller and energy storage systems in laboratory environment for further testing and verification, which will help commercialization of the proposed system design and controller.
A switch mode pulse width modulated DC-DC power converter comprises at least one first electronic circuit on a input side (1) and a second electronic circuit on a output side (2). The input side (1) and the output side (2) are coupled via at least two power transformers (T1, T2). Each power transformer (T1, T2) comprises a first winding (T1a, T2a) arranged in a input side converter stage (3, 4) on the input side (1) and a second winding (T1 b, T2b) arranged in a output side converter stage (5) on the output side (2), and each of the windings (T1a, T1 b, T2a, T2b) has a first end and a second end. The first electronic circuit comprises terminals (AO, A1) for connecting a source or a load, at least one energy storage inductor (L) coupled in series with at least one of the first windings (T1a, T2a) of the power transformers (T1, T2), and for each power transformer (T1, T2), an arrangement of switches being adapted to switch the current through the first winding (T1 a, T2a) between a first ON-state, a first OFF-state, a second ON-state with a polarity opposite to the first ON-state, and a second OFF-state, and/or being adapted to provide rectified current to the terminals (AO, A1) wherein the at least one energy storage inductor (L) is arranged so as to be charged, when all switches of the switching arrangements are conducting, and the current through the at least one first winding coupled in series to the energy storage inductor is in an OFF- state. The second electronic circuit comprises terminals (BO, B1) for connecting a load or a source, a single arrangement of switches being adapted to switch the current through the second windings (T1 b, T2b) of the power transformers (T1, T2) between a first ON-state, a first OFF-state, a second ON-state with a polarity opposite to the first ON-state, and a second OFF-state, and/or being adapted to provide rectified current to the terminals (BO, B1). The second windings (T1b, T2b) of the power transformers (T1, T2) are connected in series and coupled via the single arrangement of switches of the second circuit to the terminals (BO, B1) of the output side.
This paper presents the analysis of shaft voltage in different configurations of a doubly fed induction generator (DFIG) and an induction generator (IG) with a back-to-back inverter in wind turbine applications. Detailed high frequency model of the proposed systems have been developed based on existing capacitive couplings in IG & DFIG structures and common mode voltage sources. In this research work, several arrangements of DFIG based wind energy conversion systems (WES) are investigated in case of shaft voltage calculation and its mitigation techniques. Placements of an LC line filter in different locations and its effects on shaft voltage elimination are studied via Mathematical analysis and simulations. A pulse width modulation (PWM) technique and a back-to-back inverter with a bidirectional buckconverter have been presented to eliminate the shaft voltage in a DFIG wind turbine.
This paper presents a new z-source three phase inverter topology. The proposed topology combines the advantages of a traditional four-switch three-phase inverter with the advantages of the z impedance network (one front-end diode, two inductors and two X connected capacitors). This new topology, 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) 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 dsPIC30F3011 digital signal processor.
This paper discusses operation performance of a water pumping system consist of a brushless dc (BLDC) motor coupled a centrifugal pump and accompanying a Z-source inverter (ZSI) fed by a photovoltaic (PV) array, to be improved. Despite conventional double-stage power converters, this paper proposes utilizing a single-stage ZSI to extract the maximum power of the PV array and supply the BLDC motor simultaneously. Utilizing the ZSI provides some inherent advantages such as high efficiency and low cost, which is very promising for PV systems due to its novel voltage buck/boost capability. In addition, in order to precisely perform the maximum power point tracking (MPPT) of the PV array the fuzzy logic-incremental conductance (FL-IC) MPPT scheme is proposed. The proposed FL-IC MPPT scheme prov...
Abstract This paper proposes a full-bridge (d = 50%) cascaded buck topology which is a very suitable circuit for high voltage input-low voltage output applications with high output current. Benefiting from working under a large duty cycle, the proposed converter can easily achieve zero voltage switching turn-on and turn-off of active switches in a full bridge. Small-signal model of this topology is analyzed through its corresponding peak current mode control. Its small-signal transfer function is given, and the control loop design is discussed. Advantages of this topology and operation principles are analyzed. Design guidelines, drawn from this analysis, are applied on a low-voltage (3.3 V) output voltage prototype to validate the proposed concept. 2012 Institute of Electrical Engineers of...
An ultra-fast tracking power supply (UFTPS) for envelope tracking in a 50kHz 64-QAM Tetra2 base station power amplification system is demonstrated. A simple method for optimizing the step response of the PID+PD sliding-mode control system is presented and demonstrated, along with a PLL-based scheme for locking the switching frequency to an external clock. High UFTPS efficiency (up to 95%), very low ripple (5mVpp) and a fast step response (10?s) are obtained from a single-phase buckconverter with a 4th-order output filter. This ripple performance is demonstrated to be critical in the considered application. Also demonstrated is the effect of non-zero UFTPS output impedance on envelope tracking performance. At 13W average (156W peak) RF output, a reduction of DC input power consumption from 93W (14% efficiency) to 54W (24% efficiency) is obtained by moving from a fixed RF power amplifier supply to envelope tracking.
In this study, an integrated voltage regulation system including Maximum Power Point Tracking Algorithm (MPPT) is introduced to store and efficient use of the energy produced by renewable sources. A dsPIC is used as the main controller to obtain a rapid and stable decision-making system and to decrease the cycle time of the MPPT operation. In order to minimize the oscillations on the output voltage, a cuk converter is used that can be operated as both buck and boost modes. Thus, efficiency of the system has been increased considerably by storing the energy consistently. The experimental results validates that the system developed operates highly stable and is faster than the similar ones presented in recent literature.
This paper presents a duty cycle generator for an average model of buckconverter with current-mode control, which can simultaneously deal with both the continuous conduction model (CCM) and the discontinuous conduction mode (DCM). First, a duty cycle generator is mathematically derived, considering the transient-state of the current-loop. This technique plays an important role when the operating modes are changed under a considerable amount of step load change. Second, taking advantage of the analog behavioral modeling of PSpice, duty cycle generators for both the time and frequency domain analyses are built into a PSpice file. The accuracy of these models is verified through the computer simulations, which is compared to the actual circuit for the time domain analysis and the small signal model for the frequency analysis.
Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters, with another three types summarized for current-type inverters. These impedance networks can in principle be combined into a single generic network entity, before generalized cascading concepts are proposed for connecting multiple of them together to form energy converters with a higher output voltage gain and other unique advantages. It is anticipated that these concepts and their formed inverters can find applications in photovoltaic and other renewable systems, which in turn motivate the investigation initiated here on two-level and three-level generalized cascading concepts. In addition to their theoretical performance merits, practical shortcomings and relevant transient phenomena exhibited by the generalized concepts are discussed to provide a comprehensive knowledge base needed for weighing relevant tradeoffs before deciding on a particular application.
This paper presents the analysis of shaft voltage in different configurations of a doubly fed induction generator (DFIG) and an induction generator (IG) with a back-to-back inverter in wind turbine applications. Detailed high frequency model of the proposed systems have been developed based on existing capacitive couplings in IG & DFIG structures and common mode voltage sources. In this research work, several arrangements of DFIG based wind energy conversion systems (WES) are investigated in case of shaft voltage calculation and its mitigation techniques. Placements of an LC line filter in different locations and its effects on shaft voltage elimination are studied via Mathematical analysis and simulations. A pulse width modulation (PWM) technique and a back-to-back inverter with a bidirectional buckconverter have been presented to eliminate the shaft voltage in a DFIG wind turbine.
In this paper, a modulation strategy based on the circuit-level decoupling concept is proposed and investigated for the three-level four-leg neutral-point-clamped (NPC) inverter,with the aim of delivering power to all sorts of loads, linear/nonlinear and balanced/unbalanced. By applying the proposed modulation strategy, the four-leg NPC inverter can be decoupled into three three-level Buckconverters in each defined operating section. This makes the controller design much simpler compared to the conventional four-leg NPC inverter controllers. Also, this technique can be implemented with a simple logic and can be processed very quickly. Moreover, the switching loss is reduced substantially and the dc-link capacitors’ voltages balance is also achieved without any feedback control. The proposed modulation technique is verified by the experiment.
Abstract A half-bridge (HB) resonant inverter for driving a backlight module with multiple cold cathode fluorescent lamps (CCFLs) is proposed. Conventionally, a backlight module driving inverter is designed to operate with a low-input DC voltage. Therefore, a buckconverter is required to step down the high-output DC voltage of a power factor correction (PFC) pre-regulator. The circuit cost is high and the conversion efficiency is low. In this letter, a high-input-voltage HB resonant inverter with only one transformer is used to drive multiple lamps. Analysis and design considerations are discussed in detail. Simulations and experimental results are close to the theoretical prediction. Copyright 2010 John Wiley & Sons, Ltd.
Dynamics and stability of average current-mode control of buckconverters are analyzed by sampled-data and harmonic balance analyses. An exact sampled-data model is derived. A new continuous-time model "lifted" from the sampled-data model is also derived, and has frequency response matched with experimental data reported previously. Orbital stability is studied and it is found unrelated to the ripple size of the current-loop compensator output. An unstable window of the current-loop compensator pole is found by simulations, and it can be accurately predicted by sampled-data and harmonic balance analyses. A new S plot accurately predicting the subharmonic oscillation is proposed. The S plot assists pole assignment and shows the required ramp slope to avoid instability.
This paper applies new maximum-power-point tracking (MPPT) algorithms to a wind-turbine generator system (WTGS). In this paper, the WTGS is a direct-drive system and includes the wind-turbine, permanent-magnet (PM) synchronous generator, three-phase full bridge rectifier, buck-boost converter and load. The new MPPT method uses gradient approximation (GA) algorithm. Three methods based on GA for achieving MPPT are discussed in this paper: (1) full-sensor control with anemometer and tachometer, (2) rule-based method and (3) adaptive duty cycle method. The third method has merits of no PID parameters, proportional constant, anemometer, tachometer and characteristics of WTGS required. This method enables the permanent-magnet synchronous generator (PMSG) to operate at variable speeds to achieve good performance. Simulation results show that the tip-speed ratio (TSR) and power coefficient obtained by the adaptive duty cycle method with GA can be almost identical to the optimal values. (author)
Abstract in english A digital control algorithm for a current-mode (CM) and a voltage-mode (VM) synchronous buckconverter (SBC) is developed. In both cases, the design leads to a stable controller, even for a duty cycle larger than 50%. The desired output voltage and the transient response can be independently specified. Moreover, zero steady-state error in the output voltage can be obtained with the aid of additional dynamics. In both cases, the specification is done by pole placement usin (more) g complete state feedback. A discrete-time model is used to design the feedback gains. Both the stability and the small-signal transient response are analyzed. In another paper (Oliva et al., 2003) the control algorithms are experimentally validated with a DSP-controlled SBC.
The envelope following(EF) method is an approximate transient simulation technique which considers switching dynamics. It skips analysis of several switching cycles and considers the cycles by using, for example, the backward Euler or the trapezoidal type algorithm. It is more accurate than the averaging method because it considers switching ripples and it is still efficient. However it has been proposed only for non-autonomous systems. This paper proposes a new extended EF method which can also analyze autonomous systems which are typical in the power electronics field. It is extended by introducing a switching condition to the original one and the two conditions are solved simultaneously. In the numerical process, a Jacobian matrix is evaluated where switch timing sensitivities are considered. A hysteresis controlled buck and a C´uk converter examples are investigated and validated.
Future high voltage, high power systems in the early stages of planning include U.S. large accelerator programs such as the Next Linear Collider (NLC), Spallation Neutron Source (SNS), and international systems at DESY, CERN and KEK. There are also many nuclear fusion and multi-megawatt systems proposed for construction or upgrade. Each of these programs faces the challenge of distributing and controlling the high power required by tens to hundreds of RF amplifier tubes (e.g., klystrons) cost effectively. In this paper, we present a new approach for distributing and modulating power based upon recent technological developments in high voltage, high power, solid state switching. DTI's development of fast, high voltage, opening and closing solid state switches enable, for the first time at high voltage, a nearly lossless "DC transformer". With this DC transformer (i.e., down converter or buck regulator), it is now possible to distribute unregulated high voltage DC power in a large facility, and regulate and con...
This study was interested in the management of an energy production unit. A variable speed wind turbine (VSWT) was used as a principal source and a supercapacitor (SC) module was used as an energy storage system. Both were connected through a direct current bus. This unit was supplying a three-phase load using an inverter and an inductor and capacitor filter. In order to regulate the direct current bus voltage, the SC storage state was controlled by using a buck-boost converter according to load instructions and wind speed fluctuations. Then, a resonant controller was established to avoid any disturbances and to control the alternating line-to-line voltages of the load which may be unbalanced. This study has shown that the stability of the three-phase voltage source depends on the direct c...
