Pulse Width Modulation DC-DC Research Articles

A new lossless passive snubber with simple structure for pulse width modulation DC-DC converters

A new lossless passive snubber for pulse width modulation converters is introduced in this paper. This snubber is established zero current switching condition for main switch in the converters for turning on distance. This snubber does not impose any additional current stress on the switch. The snubber can be applied to all single-switch DC-DC converters. A boost converter with the proposed snubber is analyzed and to verify theoretical analysis a 200 W sample is implemented and tested, also the experimental results are presented. In order to investigate the effect of snubber circuit in the converter in terms of efficiency, the boost converter with the proposed snubber has been compared in terms of efficiency with the conventional boost converter and the results show that the efficiency has increased by about 7% despite the snubber.

Time-domain Dynamic-performance-improvement Method for Pulse-width-modulated DC-DC Converters Based on Eigenvalue and Eigenvector Sensitivity

For pulse-width modulated (PWM) DC-DC converters, the input voltage fluctuation and load variation in practical applications make it necessary for them to have better dynamic performance to meet the regulation requirements of the system. The dynamic-performance-improvement method for PWM DC-DC converters is mainly based on indirect dynamic performance indices, such as the gain margin and phase margin. However, both settling time and overshoot in the time domain are important in practical engineering. This makes it difficult for designers to obtain a clear understanding of the time-domain dynamic performance that can be achieved with improved control. In this study, a direct analysis of the time-domain dynamic characteristic of PWM DC-DC converters is performed. A dynamic-performance-improvement method based on eigenvalues and eigenvector sensitivity (E <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> S-based DPIM) is proposed to directly improve the time-domain dynamic performance index of PWM DC-DC converters. By considering a boost converter with proportional-integral control as an example, an additional virtual inductor current feedback control was designed using the proposed dynamic-performance-improvement method. Simulation and experimental results verify the validity and accuracy of the proposed dynamic-performance-improvement method.

Simplified Nonlinear Current-Mode Control of DC-DC Cuk Converter for Low-Cost Industrial Applications.

This paper presents a robust nonlinear current-mode control approach for a pulse-width modulated DC-DC Cuk converter in a simple analog form. The control scheme is developed based on the reduced-state sliding-mode current control technique, in which a simplified equivalent control equation is derived using an averaged power converter model in continuous conduction mode. The proposed controller does not require an output capacitor current sensor and double proportional-integral compensators as in conventional sliding-mode current controllers; thus, the cost and complexity of the practical implementation is minimized without degrading the control performance. The simplified nonlinear controller rejects large disturbances, provides fast transient response, and maintains a constant switching frequency. The nonlinear control scheme is developed using an analog circuit with minimal added components, which is suitable for low-cost industrial applications. The control law derivation, control circuit design, controller gains selection, and stability analysis are provided. The proposed control methodology is verified via simulating the closed-loop nonlinear power converter model in MATLAB/SIMULINK under abrupt changes in load current and input voltage. The simulation results show that the proposed control scheme provides robust tracking performance, a low percentage overshoot, fast transient response, and a wide operating range. The maximum percentage overshoot and settling time of the closed-loop power converter response during line disturbance are 5.6% and 20 ms, respectively, whereas the percentage overshoot and settling time during load disturbance are 2.8% and 15 ms, respectively.

Interval Type-2 Fuzzy Logic Controlled Shunt Converter Coupled Novel High-Quality Charging Scheme for Electric Vehicles

The deployment of electric vehicle charging stations degrades the quality of power in the distribution grid. This article proposes an interval type-2 fuzzy logic controlled shunt converter coupled novel high-quality charging scheme for electric vehicles. This system includes three-phase bidirectional front-end ac-dc pulsewidth modulation (PWM) converter, backend dc-dc PWM converter and three-phase three-wire distribution static compensator. The bidirectional converters help to perform both grid to vehicle and vehicle to grid mode of operations. The combination of dc-link voltage with decoupled current control technique is exploited for ac-dc converter. A multistep constant current control technique is proposed for the dc-dc converter to charge and discharge the battery. A fuzzy logic controller based instantaneous reactive power theory control method is proposed for shunt converter. The performance of type-1, interval type-2, and real coded genetic algorithm optimized fuzzy logic controllers are evaluated by the shunt converter dc-link voltage and the total harmonic distortion of the source current. Lithium-ion batteries are utilized as an energy storage device for electric vehicles in the proposed system. The entire system is modeled and evaluated in the MATLAB/Simulink environment. An interval type-2 and real coded genetic algorithm optimized fuzzy logic controller affords the better performance during V2G and G2V operations, respectively.

Improved Markov Model for Reliability Assessment of Isolated Multiple-Switch PWM DC-DC Converters

This paper proposes a comprehensive Markov model to study the reliability performance of the conventional isolated multiple-switch pulse width modulation DC-DC (IMSDC-DC) converters including full-bridge, half-bridge and push-pull DC-DC topologies. The suggested model helps to achieve more precise outcomes with a better reflection of the real-world operation characteristics by (i) relying on self-embedded fault tolerant capability of the IMSDC-DC converters, (ii) considering the probability of both short and open circuit (SC and OC) faults in each component, (iii) assessing the effect of semiconductors’ SC/OC probability on the converters’ reliability, (iv) analyzing the continuous and discontinuous conduction modes, (v) updating the operational characteristics of the converters after each fault occurrence, and (vi) evaluating control of the converters to have more durable power transfer in some post-fault cases. Then, the model is applied to assess the effects of duty cycle, output power, voltage gain and transformer turns ratio on the overall reliability and mean time to failure. Practical analytic conclusions are followed by some experimental results to verify the accuracy of the proposed model.

Reliability Assessment of Conventional Isolated PWM DC-DC Converters

This paper sets forth the reliability analysis of conventional isolated pulse width modulation DC-DC (IDC-DC) converters. The IDC-DC converters are categorized into isolated single-switch DC-DC (ISSDC-DC) or multiple-switch DC-DC (IMSDC-DC) converters. The proposed framework encompasses analyzing the impacts of duty cycle, input voltage, output power, transformer turns ratio, components characteristics and time duration on the overall reliability performance of the IDC-DC converters. The suggested reliability assessment is centered on Markov models characterized by taking into consideration all open and short circuit faults on the components in both continuous and discontinuous conduction modes. We further investigate the self-embedded fault tolerant capability of the IMSDC-DC converters under open circuit fault scenarios on the switches, diodes and blocking capacitors, where we offer new reliability analytics. Along with extensive analyses and comparisons, several experimental results are provided to verify the self-embedded fault tolerant capability of IMSDC-DC converters.

Thermal analysis of non‐isolated conventional PWM‐based DC–DC converters with reliability consideration

This paper proposes analytics for reliability assessment of non-isolated conventional pulse width modulation DC-DC (NIDC-DC) converters. This class of converters consists of conventional Buck, Boost, Buck–Boost, Cuk, Sepic and Zeta topologies. The proposed analytics are founded based on the Markov process principles and can effectively capture the effects of duty cycle, input voltage, output power, voltage gain, components characteristics and aging on the overall reliability performance and mean time to failure of the NIDC-DC converters. Furthermore, the suggested framework takes both continuous and discontinuous conduction modes of each converter into account, with which the open and short circuit faults in the components are analysed. As an important outcome, the most reliable operation region of the NIDC-DC converters are obtained with respect to different operational parameters, which is useful in design procedure. Eventually, extensive thermal experiments with an appropriate reflection of reliability metric are conducted to measure the components’ temperatures and verify their performance in different operating conditions.

A soft switching with reduced voltage stress ZVT-PWM full-bridge converter.

This paper introduces a novel active snubber cell for soft switching pulse width modulation DC-DC converters. In the proposed converter, the main switch is turned on under zero voltage transition and turned off under zero voltage switching (ZVS). The auxiliary switch is turned on under zero current switching (ZCS) and turned off under zero current transition. The main diode is turned on under ZVS and turned off under ZCS. All of the other semiconductors in the converter are turned on and off with soft switching. There is no extra voltage stress on the semiconductor devices. Besides, the proposed converter has simple structure and ease of control due to common ground. The detailed theoretical analysis of the proposed converter is presented and also verified with both simulation and experimental study at 100 kHz switching frequency and 600 W output power. Furthermore, the efficiency of the proposed converter is 95.7% at nominal power.

Stability Analysis With Considering the Transition Interval for PWM DC-DC Converters Based on Describing Function Method

The nonlinearity of the switching process in DC–DC converters can result in the inaccuracy and invalidation of traditional stability criterion based on linear modeling, which is very harmful in practice, especially for the DC-DC converters with high stability requirements. In this paper, the describing function method is adopted for the modeling of switching process, namely, pulse width modulation (PWM), in DC–DC converters, and the describing function of the PWM is derived in detail. Considering the nonlinear items in the obtained describing function of PWM, the selection of the parameters in these nonlinear items are first provided and proved in this paper. With the obtained describing function, the stability of the PWM DC–DC converter can be analyzed exactly. Taken a PWM boost converter as an example, the nonlinear model based on describing function and the linear model are established, respectively; furthermore, the stability analysis based on these two kinds of models are carried out. Comparing with the traditional linear stability criterion, the simulation and experimental results validate the effectiveness and accuracy of the stability analysis based on describing function method. Furthermore, the transition interval of the PWM DC–DC converter from a stable region to an unstable region can be determined exactly by the proposed stability analysis method, which is helpful to determine the stability margin in real engineering applications. Therefore, this paper provides a practical stability analysis method for PWM DC–DC converters.

High-Frequency Soft-Switching PWM DC-DC Converter with Active Output Rectifier Operating as a Current Source for Arc Welding Applications

This paper introduces a high-frequency soft-switching pulse-width modulation DC-DC power converter with secondary active rectifier tested as a DC current source for arc welding applications. The soft-switching DC-DC converter consists of a high-frequency full-bridge inverter, high-frequency power transformer, and a controlled output rectifier with new secondary energy recovery turn-off snubber. Circulating currents in the converter are reduced by using active rectifier, and RMS values of the currents in primary and secondary switches are decreased by utilizing a novel control algorithm. The experimental results of a 4.5 kW DC-DC converter working at switching frequency of 100 kHz are presented.

Accurate Modeling of Nonideal Low-Power PWM DC-DC Converters Operating in CCM and DCM using Enhanced Circuit-Averaging Techniques

The development of enhanced modeling techniques for the simulation of switched-mode Pulse Width Modulated (PWM) DC-DC power converters using circuit averaging is the main focus of this article. The circuit-averaging technique has traditionally been used to model the behavior of PWM DC-DC converters without considering important nonideal characteristics of the switching devices. As a result, most of these existing approaches present simplified models that are ideal or linearized, and do not accurately account for the performance characteristics of the converter. This is especially problematic for low-power applications. In this article, we present an enhanced nonideal behavioral circuit-averaged model that makes the simulation of DC-DC converters both computationally efficient and accurate, thereby presenting an important tool for circuit designers. Experimentally, we show that our Verilog-A-based new model allows for accurate simulation of both Buck- and Boost-type PWM converters operating in either CCM or DCM modes while providing more than one order of magnitude speedup over the transistor-level simulation.

Family of single‐switch soft‐switching pulse‐width modulation DC–DC converters with reduced switch stress

In this study, a new family of pulse width modulation DC-DC converters is introduced. The proposed converters have one switch that turns on at zero current switching condition and turns off at zero voltage switching condition. The proposed auxiliary circuit can be used instead of converter switch in any non-isolated and isolated DC-DC converter. The buck converter from this converter family is analysed and its operating modes are discussed. The design considerations are presented and a prototype is realised. The experimental results confirm the validity of theoretical analysis.

ZCS-PWM Converter for Reducing Switching Losses

Zero-current (ZC) switching pulse-width modulated (PWM) fly back DC-DC converter is an extended version of the single switch fly back converter with an auxiliary circuit. The main switch and auxiliary switch operate at ZCS turn-on and turn-off conditions, and all uncontrolled devices in the converter operate at zero-voltage-switching (ZVS) turn-on and turn-off. Soft switching techniques are used in PWM DC-DC converters to reduce switching losses and electromagnetic interference (EMI). The circulating current for the soft switching flows only through the auxiliary circuit, the conduction loss and current stress of the main switch are minimized. The general principle of operation of ZCS flyback converter, its merits and demerits, experimental setup and results has been summarized.

Control-to-output transfer function of peak current-mode controlled pulse-width modulated dc–dc buck converter in continuous conduction mode

The control-to-output transfer function is essential for the design of the compensator in the outer-voltage loop as it represents the plant for the outer-voltage loop in the peak current-mode-controlled converters. The control-to-output transfer function for the peak current-mode-controlled pulse-width-modulated (PWM) dc-dc buck converter is derived using power-stage transfer functions and the modulator transfer function in the inner-current loop. Experimental Bode plots are presented to verify the derived transfer function. The required critical path open-loop duty cycle-to-inductor current and duty cycle-to-output voltage transfer functions for a peak current-mode controlled dc-dc PWM buck converter are derived and experimentally verified. The theoretical results were in good agreement with all the measured Bode plots.

Grid-tied Power Conditioning System for Fuel Cell Composed of Three-phase Current-fed DC-DC Converter and PWM Inverter

This paper proposes a grid-tied power conditioning system for fuel cell, which consists of three-phase current-fed DC-DC converter and three-phase PWM inverter. The three-phase current-fed DC-DC converter boosts fuel cell voltage of 26-48 V up to 400 V with zero-voltage switching (ZVS) scheme, while the three-phase PWM(Pulse Width Modulation) inverter controls the active and reactive power supplied to the grid. The operation of the proposed power conditioning system with fuel cell model is verified through simulations with PSCAD/EMTDC software. The feasibility of hardware implementation is verified through experimental works with a laboratory prototype with 1.2 kW proton exchange membrane (PEM) fuel cell stack. The proposed power conditioning system can be commercialized to interconnect the fuel cell with the power grid.

High step-up zero-voltage switching current-fed isolated pulse width modulation DC–DC converter

This study presents a new zero-voltage switching (ZVS) current-fed isolated pulse width modulation DC-DC converter. In this converter all switches turn on under zero-voltage zero-current switching and turn off under almost ZVS. Furthermore, the voltage spike across the main switch due to leakage inductance of isolating transformer is absorbed. Considering high efficiency and voltage gain of this converter, it is suitable for green generated systems such as fuel cells or photovoltaic systems. The proposed converter operating modes are analysed and theoretical waveforms are shown. The presented experimental results confirm the integrity of the proposed converter.

An Autotuning Digital Controller for DC–DC Power Converters Based on Online Frequency-Response Measurement

This paper describes a hardware-description-language-coded autotuning algorithm for digital PID-controlled DC-DC power converters based on online frequency-response measurement. The algorithm determines the PID controller parameters required to maximize the closed-loop bandwidth of the feedback control system while maintaining user-specified stability margins and integral-based no-limit-cycling criteria, as well as ensuring single-crossover-frequency operation and sufficiently high loop gain magnitude at low frequencies. Experimental results are provided for five different pulsewidth-modulated DC-DC converters, including a well-damped synchronous buck, a lightly damped synchronous buck with and without a poorly damped input filter, a boost operating in continuous-conduction mode, and a boost operating in discontinuous-conduction mode.

Power converters and amplifiers (review of "Pulse-Width Modulated DC-DC Power Converters" by Kazimierczuk, M.K.; 2008) [Book News

This book is a comprehensive textbook in the areas of electrical, electronics, and telecommunications engineering. It consists of 17 chapters and two appendices. Some of the topics covered include: buck PWM DC-DC converters; boost PWM DC-DC converters; buck-boost-PWM DC-DC converters; half-bridge and full-bridge converters; push-pull PWM DC-DC converters; open-loop small-signal characteristics of boost converters for CCM; current-mode control of boost converters; silicon and silicon carbide power diodes; and soft-switching DC-DC converters. Appendix A is an introduction to SPICE and Appendix B provides an introduction to MATLAB. Answers to problems and the index are also included at the end of the book. The book is recommended for senior undergraduate and graduate students but also for practicing engineers working with switch-mode power supplies, within applications such as computers, telecommunications, industrial electronic systems, automobile electronics, medical equipment, radars, and aerospace power technology.

Fuzzy control of DC-DC switching converters: stability and robustness analysis

This paper presents the design of a fuzzy controller for PWM (pulse width modulation) DC-DC switching converter based on the Takagi-Sugeno (TS) fuzzy modelling approach. Stability and robustness conditions are derived for the fuzzy control system to help the design of the fuzzy controlled DC-DC converter. Simulation and experimental results on regulating a boost DC-DC converter subject to large load changes by using the proposed fuzzy controller are given. The transient response is compared to that controlled by a traditional PI controller.

Higher constant switching frequency-based HF-link half-bridge PWM DC-DC converter topology with ZCS commutations

A novel zero current soft switching (ZCS) pulse width modulation (PWM) half-bridge DC-DC converter is presented. ZCS commutation can be achieved for a wide load power setting with the asymmetrical PWM-based duty-cycle control scheme under a constant switching frequency. The effectiveness of the proposed converter topology and soft switching scheme are demonstrated with experimental results using the 0.8 kW - 55 kHz prototype.