Self-commutated auxiliary circuit ZVT PWM converters

This paper introduces a novel class of zero voltage transition (ZVT) DC/DC pulse-width modulation (PWM) converters that use a resonant inductance-capacitance (L-C) circuit connected to the auxiliary switch, which is termed a self-commutated auxiliary circuit. It provides a simple and reliable means of achieving zero-current conditions (ZCS) for auxiliary switch commutations under wide line and load ranges, without the inclusion of any kind of DC voltage source. Furthermore, this auxiliary circuit is placed in parallel with the main power converter, retaining the ZVT characteristics. The self-commutated auxiliary circuit ZVT PWM boost is analyzed, and its feasibility and reliability are confirmed by experimental results obtained from laboratory prototypes rated at 1 kW and 100 kHz.     

Design and analysis of a novel zero-voltage-transition interleaved boost converter for renewable power applications

High-efficiency stepping up operation is an important feature of the converters used in renewable power applications due to the low voltage level of photo-voltaic arrays and fuel cells. Decreasing the switching losses of the converters is an effective solution for increasing the converter efficiency, especially in high-power applications. This article presents a novel zero-voltage-transition (ZVT) interleaved dc–dc boost converter that can be used in renewable power sources to reduce switching losses. The auxiliary circuit used in the proposed converter is composed of only one auxiliary switch and a minimum number of passive components without an important increase in the cost and complexity. The main advantage of the proposed converter is that it not only provides ZVT in the boost switches but also provides soft switching in the auxiliary switch. Another advantage of the proposed topology is that the semiconductor devices used in the converter do not have any additional voltage or current stresses. Also, it has a simple structure, low cost and ease of control. In this article, a detailed steady-state analysis of the proposed converter is presented. The theoretical analysis is verified via simulation and experimental studies which are in very good agreement.     

A new ZVT-ZCT-PWM DC-DC converter

In this paper, a new active snubber cell is proposed to contrive a new family of pulse width modulated (PWM) converters. This snubber cell provides zero voltage transition (ZVT) turn on and zero current transition (ZCT) turn off together for the main switch of a converter. Also, the snubber cell is implemented by using only one quasi resonant circuit without an important increase in the cost and complexity of the converter. New ZVT-ZCT-PWM converter equipped with the proposed snubber cell provides most the desirable features of both ZVT and ZCT converters presented previously, and overcomes most the drawbacks of these converters. Subsequently, the new converter can operate with soft switching successfully at very wide line and load ranges and at considerably high frequencies. Moreover, all semiconductor devices operate under soft switching, the main devices do not have any additional voltage and current stresses, and the stresses on the auxiliary devices are at low levels. Also, the new converter has a simple structure, low cost and ease of control. In this study, a detailed steady state analysis of the new converter is presented, and this theoretical analysis is verified exactly by a prototype of a 1-kW and 100-kHz boost converter.     

Novel zero-voltage-transition current-fed full-bridge PWM converterfor single-stage power factor correction

A novel zero-voltage-transition (ZVT) current-fed full-bridge pulsewidth modulation (PWM) power converter for single-stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter. A simple auxiliary circuit which includes only one active switch provides a zero-voltage-switching (ZVS) condition to all semiconductor devices (two active switches are required for the previous ZVT converter). This leads to reduced cost and a simplified control circuit compared to the previous ZVT converter. The ZVS is achieved for wide line and load ranges with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed power converter are presented and verified by the experimental results from a 1.5 kW 100 kHz laboratory prototype     

A zero-voltage transition boost converter using a zero-voltage switching auxiliary circuit

A soft switching boost converter with zero-voltage transition (ZVT) main switch using zero-voltage switching (ZVS) auxiliary switches is proposed. Various operating intervals of the converter are presented and analyzed. Design considerations are discussed. A design example with experimental results obtained from a 300-W, 250-kHz, 300-V output DC-DC converter is presented. A modified gating scheme to utilize the auxiliary switch in the main power processing is discussed. A 600-W, 100-kHz, 380 V output, 90-250 V AC, power factor corrected, AC-to-DC, boost converter with the modified gating scheme is presented. Results show that the main switch maintains ZVT while auxiliary switches retain ZVS for the complete specified line and load conditions. Parasitic oscillations existing in the converters proposed in the literature are completely removed.     

Novel ZVT-PWM converters with active snubbers

An active snubber cell is proposed to contrive zero-voltage-transition (ZVT) pulsewidth-modulated (ZVT-PWM) converters. Except for the auxiliary switch, all active and passive semiconductor devices in a ZVT-PWM converter operate at zero-voltage-switching (ZVS) turn on and turn off. The auxiliary switch operates at ZVS turn off and near zero current-switching (ZCS) turn on. An analytical study on a boost ZVT-PWM converter with the proposed active snubber cell is presented in detail. A 750 W 80 kHz prototype of the boost ZVT-PWM converter has been built in the laboratory to experimentally verify the analysis. Six basic ZVT-PWM converters can be easily created by attaching the proposed active snubber cells to conventional PWM converters. A detailed design procedure of the proposed active snubber cell is also presented in this paper     

Integrated ZVT auxiliary commutation circuit for input stage of double-conversion UPSs

This paper proposes an integrated zero voltage transition (ZVT) auxiliary commutation circuit applied to a universal input ac/dc system with a bidirectional converter for dc bus and battery bank interface. With the bidirectional converter it is possible to reduce the cost of the battery bank and virtually eliminate both low and high frequency current ripple in the batteries. An integrated ZVT auxiliary commutation circuit has been included to the system to achieve ZVT commutation at the main switches in all operation modes. In addition, this auxiliary commutation circuit controls the di/dt of the resonant process, allowing the utilization of slow diodes [intrinsic diodes of metal oxide semiconductor field effect transistors (MOSFETs)] in the bidirectional converter and, therefore, reducing the overall system cost. Integrated commutation circuit is based on a new concept in which the energy involved in one or more commutation processes is utilized to assist another commutation processes. Moreover, a control system has been developed and analyzed for the correct operation of the proposed system. Experimental results based on a 580-W prototype are presented to demonstrate the good performance of the proposed system.     

一种新型软开关DC-DC PWM升压变换器设计

为提高转换效率并降低电源开关的电流应力,提出一种基于新型有源缓冲电路的PWM DC-DC升压变换器。该有源缓冲电路使用ZVT—ZCT软开关技术,分别提供了总开关ZVT开启及ZCT闭合、辅助开关ZCS开启及ZCT闭合。消除了总开关额外的电流及电压应力,消除了辅助开关电压应力,且有源缓冲电路的耦合电感降低了电流应力。另外,通过连续将二极管添加到辅助开关电路,防止来自共振电路的输入电流应力进入总开关。实验结果表明,相比传统的PWM变换器,新的DC-DC PWM升压变换器在满负荷时电流应力降低且总体效率能达到98.7%。     

Zero-Voltage-Transition PWM Converters With Synchronous Rectifier

In this paper, a family of zero-voltage-transition (ZVT) pulsewidth-modulated converters with synchronous rectifier (SR) is introduced. The SR decreases the conduction losses, while it increases the achieved soft switching range. In this family of converters, zero-voltage-switching (ZVS) condition is attained for the main and rectifier switches. Also, zero-current switching is achieved for the auxiliary switch. In addition, the applied ZVS technique can eliminate the reverse recovery losses of the rectifier switch body diode. The ZVT buck converter with SR is analyzed, and the presented experimental results confirm the theoretical analysis.      

软开关PWM变换器发展综述

软开关技术已从基本谐振变换器,准谐振变换器和谐振直流环节变换器发展到软开关ＰＷＭ变换器。软开关ＰＷＭ变换器综合了软开关技术和ＰＷＭ技术各自的优点,构成新一类目前发展和应用前景的变换器。本文系统地综述了谐振直流环变换器,零电压和零电流开关ＰＷＭ变换器,零电压转换ＰＷＭ变换器和零电流转换ＰＷＭ变换器的工作原理和特点。     

A Comparative Study of Zero-Current-Transition PWM Converters

Zero-current-transition pulsewidth-modulation (ZCT-PWM) boost converters are conventional boost converters that use an active auxiliary circuit to turn off the main power switch with zero-current switching; the operation and properties of these converters are the focus of this paper. In this paper, the general operating principles behind all ZCT-PWM converters are reviewed, and the operation and properties of specific converters are discussed. The strengths and weaknesses of each converter are stated, and a new and improved ZCT-PWM boost converter is proposed and discussed. Experimental results obtained from an experimental ZCT-PWM boost converter prototype implemented with several of the auxiliary circuits discussed in this paper are presented, and the results confirm the superior performance of the proposed converter     

A zero-voltage-switched PWM boost converter with an energyfeedforward auxiliary circuit

A zero-voltage-switched (ZVS) pulsewidth-modulated (PWM) boost converter with an energy feedforward auxiliary circuit is proposed in this paper. The auxiliary circuit, which is a resonant circuit consisting of a switch and passive components, ensures that the converter's main switch and boost diode operate with soft switching. This converter can function with PWM control because the auxiliary resonant circuit operates for a small fraction of the switching cycle. Since the auxiliary circuit is a resonant circuit, the auxiliary switch itself has both a soft turn on and turn off, resulting in reduced switching losses and electromagnetic interference (EMI). This is unlike other proposed ZVS boost converters with auxiliary circuits where the auxiliary switch has a hard turn off. Peak switch stresses are only slightly higher than those found in a conventional PWM boost converter because part of the energy that would otherwise circulate in the auxiliary circuit and drastically increase peak switch stresses is fed to the load. In this paper, the operation of the converter is explained and analyzed, design guidelines are given, and experimental results obtained from a prototype are presented. The proposed converter is found to be about 2%-3% more efficient than the conventional PWM boost converter     

A zero voltage transition boost converter employing a soft switching auxiliary circuit with reduced conduction losses

This paper presents a zero-voltage-transition (ZVT) boost converter using a soft switching auxiliary circuit for power factor correction (PFC) applications. The improvement over existing topologies lies in the positioning of the auxiliary circuit capacitors and the subsequent reduction in the resonant current and therefore the conduction losses as compared to other similar topologies. The proposed converter operates in two modes - Mode 1 and Mode 2. It is shown in the paper that the converter should be designed using the constraints obtained in Mode 1 to achieve low-loss switching. The converter is analyzed and characteristic curves presented which are then used in a detailed design example. Experimental results from a 250 W, 127 V input laboratory prototype switching at 100 kHz verify the design process and highlight the advantages of the proposed topology. The proposed converter is suitable for single-phase, two stage power factor correction circuits with universal input voltage range and power levels up to 3 kW.     

Family of Zero-Current Transition PWM Converters

In this paper, a new auxiliary circuit is introduced for applying to buck, buck-boost, zeta, forward, and flyback converters. This auxiliary circuit provides a zero-current switching condition for all switching elements. The proposed zero-current transition (ZCT) pulsewidth-modulated buck converter is briefly described. Also, a ZCT flyback converter is analyzed, and its different operating modes are presented. Design considerations are explained, and a design example along with the experimental results of the ZCT flyback converter is presented.     

Differential-Mode EMI Reduction in a Multiphase DCM Flyback Converter

Switched converters are a source of electromagnetic interference (EMI) due to the hard switching and abrupt edges in the current and voltage waveforms. Multiphase converters can reduce the EMI at the source, minimizing the conducted EMI generation, without changing dramatically the normal operation of the circuit. Input filter can be greatly reduced, radiated EMI is lower, and internal EMI problems are minimized. This paper is focused on exploring multiphase converters as a topological technique to reduce conducted differential-mode EMI generation at the source, considering some nonidealities of the multiphase converter.      

Implementation of single-phase boost power-factor-correctioncircuits in three-phase applications

A three-phase rectifier employing three single-phase boost power-factor-correction circuits is analyzed. Each converter operates in the continuous conduction mode (CCM), which allows a high power factor and a small EMI filter. Current sharing is ensured by a common voltage loop driving the individual current loops of the three converters. A suitable circuit arrangement is devised to limit phase interaction. The zero-voltage-transition technique (ZVT) is successfully applied to each converter, in order to obtain zero turn on losses and soft turnoff of the freewheeling diodes. Results of a 1800-W 100-kHz experimental prototype are reported, which confirm the theoretical forecasts     

Zero-Voltage and Zero-Current Switching Full-Bridge DC–DC Converter With Auxiliary Transformer

A novel zero-voltage and zero-current switching (ZVZCS) full-bridge phase-shifted pulsewidth modulation (PWM) converter using insulated gate bipolar transistors (IGBTs) with auxiliary transformer is proposed to improve the properties of the previously presented converters. ZVZCS for all power switches is achieved for full load range from no-load to short circuit by adding active energy recovery snubber and auxiliary circuits. The principle of operation is explained and analyzed and experimental results are presented. The features and design considerations of the converter are verified on a 3-kW, 50-kHz IGBT based experimental circuit.     

IBC Using a Single Resonant Inductor for High-Power Applications

In this paper, an interleaved boost converter (IBC) with a zero-voltage-transition (ZVT) cell using a single resonant inductor in continuous conduction mode is proposed. The IBC with the proposed ZVT cell has advantages such as a simple circuit, reduced size, and low cost by using a single resonant inductor. It is more suitable for high-power applications. The proposed ZVT cell circuit and principles for the IBC are explained in detail. The validity of the IBC with the proposed ZVT cell is verified through experimental results.     

Novel zero-voltage and zero-current-switching (ZVZCS) full-bridge PWM converter using coupled output inductor

A novel zero-voltage and zero-current-switching (ZVZCS) full-bridge pulse-width-modulated (PWM) converter is proposed to improve the previously proposed ZVZCS full-bridge PWM converters. By employing a simple auxiliary circuit with neither lossy components nor active switches, soft-switching of the primary switches is achieved. The proposed converter has many advantages such as simple auxiliary circuit, high efficiency, low voltage stress of the rectifier diode and self-adjustment of the circulating current, which make the proposed converter attractive for the high voltage and high power applications. The principles of operation and design considerations are presented and verified on the 4 kW experimental converter operating at 80 kHz.     

Zero-Voltage Transition Current-Fed Full-Bridge PWM Converter

In this paper, a new zero-voltage transition current-fed full-bridge converter with a simple auxiliary circuit is introduced for high step-up applications. In this converter, for the main switches, zero-voltage switching condition is achieved at wide load range. Furthermore, all semiconductor devices of the employed simple auxiliary circuit are fully soft switched. The proposed converter is analyzed and a prototype is implemented. The experimental results presented confirm the validity of the theoretical analysis. Finally, the proposed auxiliary circuit is applied to other current-fed topologies such as current-fed push-pull and half-bridge converters to provide soft switching.