A true ZCZVT commutation cell for PWM converters

This paper introduces a true zero-current and zero-voltage transition (ZCZVT) commutation cell for DC-DC pulsewidth modulation (PWM) converters operating with an input voltage less than half the output voltage. It provides zero-current switching (ZCS) and zero-voltage switching (ZVS) simultaneously, at both turn on and turn off of the main switch and ZVS for the main diode. The proposed soft-switching technique is suitable for both minority and majority carrier semiconductor devices and can be implemented in several DC-DC PWM converters. The ZCZVT commutation cell is placed out of the power path, and, therefore, there are no voltage stresses on power semiconductor devices. The commutation cell consists of a few auxiliary devices, rated at low power, and it is only activated during the main switch commutations. The ZCZVT commutation cell, applied to a boost converter, has been analyzed theoretically and verified experimentally. A 1 kW boost converter operating at 40 kHz with an efficiency of 97.9% demonstrates the feasibility of the proposed commutation cell     

An improved ZCS-PWM commutation cell for IGBT's application

An improved zero-current-switching pulsewidth-modulation (ZCS-PWM) commutation cell is proposed, which is suitable for high-power applications using insulated gate bipolar transistors (IGBTs) as the power switches. It provides ZCS operation for active switches with low-current stress without voltage stress and PWM operating at constant frequency. The main advantage of this cell is a substantial reduction of the resonant current peak through the main switch during the commutation process. Therefore, the RMS current through it is very close to that observed in the hard-switching PWM converters. Also, small ratings auxiliary components can be used. To demonstrate the feasibility of the proposed ZCS-PWM commutation cell, it was applied to a boost converter. Operating principles, theoretical analysis, design guidelines and a design example are described and verified by experimental results obtained from a prototype operating at 40 kHz, with an input voltage rated at 155 V and 1 kW output power. The measured efficiency of the improved ZCS-PWM boost converter is presented and compared with that of hard-switching boost converter and with some ZCS-PWM boost converters presented in the literature. Finally, this paper presents the application of the proposed soft-switching technique in DC-DC nonisolated power converters     

An improved family of ZVS-PWM active-clamping DC-to-DC converters

A new family of DC-to-DC converters featuring clamping action, PWM modulation and soft-switching (ZVS) in both active and passive switches, is proposed to overcome the limitations of clamped mode DC-to-DC converters. The new family of converters is generated and the new circuits are presented. As the resonant circuits absorb all parasitic reactances, including transistor output capacitance and diode junction capacitance, these converters are suitable for high-frequency operation. Principle of operation of the boost converter, theoretical analysis, simulation and experimental results are presented, taken from a laboratory prototype rated at 1600 W, input voltage of 300 V, output voltage of 400 V, and operating at 100 kHz. The measured efficiency at full load was 98%     

A Soft-Switched Full-Bridge Single-Stage AC-to-DC Converter With Low-Line-Current Harmonic Distortion

A single-phase high-frequency transformer-isolated soft-switching single-stage ac-to-dc converter with low-line-current distortion is presented. The circuit configuration is obtained by integrating two discontinuous current mode (DCM) boost converters with a DCM full-bridge buck converter. The zero-voltage switching for the top switches is achieved automatically, whereas bottom switches are aided by zero-voltage transition circuits. The output voltage is regulated by duty-cycle control at constant switching frequency. The intervals of operation and steady-state analysis are presented. A systematic design procedure is presented with a 1-kW converter design example. PSPICE simulation and experimental results obtained from a 1-kW laboratory prototype are presented for a wide variation in line and load conditions.     

A family of low EMI unity power factor converters

A new family of soft-switching unity power factor converters with high input power factor and isolated output is presented. A feature of the converters is a significant reduction of conducted electromagnetic interference (EMI). Six converter topologies have been identified that share a zero-voltage-switching (ZVS) phase arm on the input boost converter stage. Detailed analysis and experimental results are presented on the double ZVS phase-arm resonant transition converter     

Large-signal modeling of hysteretic current-programmed converters

Large-signal dynamic models for hysteretic current-programmed buck, boost, and buck-boost converters are proposed. The model is expressed by a single differential equation. The small-signal transfer functions of these three converters are also derived, based on the large-signal model. The analysis shows that under the hysteretic current-programmed control, the output voltage of the buck converter is independent of the supply voltage, and there is a right-halfplane (RHP) zero in the control-to-output transfer function of boost and buck-boost converters. An experimental prototype is breadboarded to verify the analysis     

A new soft-switched PWM boost converter with a lossless auxiliary circuit

A soft-switching scheme for the PWM boost converter is newly proposed to obtain the desirable features of both the conventional PWM boost and resonant converters such as ease of control, reduced switching losses and stresses, and low EMI. In order to achieve the soft-switching action, the proposed scheme employs an auxiliary circuit, which is added to the conventional boost converter and used to achieve soft-switching for both the main switch and the output diode while not incurring any additional losses due to the auxiliary circuit itself. The basic operations, in this paper, are discussed and design guidelines are presented. Through a 100?KHz, 60?W prototype, the usefulness of the proposed scheme is verified.     

Two Types of KY Buck–Boost Converters

A novel voltage-bucking/boosting converter, named as KY buck–boost converter (i.e., 2D converter), is presented herein. Unlike the traditional buck–boost converter, this converter possesses fast transient responses, similar to the behavior of the buck converter with synchronous rectification. In addition, it possesses the nonpulsating output current, thereby not only decreasing the current stress on the output capacitor but also reducing the output voltage ripple. Furthermore, it has the positive output voltage, different from the negative output voltage of the traditional buck–boost converter. Above all, there are two types of KY buck–boost converters presented herein. In this paper, the basic operating principles of the proposed converters are first illustrated in detail, and second, some experimental results are offered to verify the effectiveness of the proposed topologies.      

Properties and synthesis of passive lossless soft-switching PWMconverters

This paper derives general topological and electrical properties common to all lossless passive soft-switching power converters with defined characteristics, and proposes a synthesis procedure for the creation of new power converters. The synthesis procedure uses the properties to determine all possible locations for the resonant inductors and capacitors added to achieve soft switching. A set of circuit cells is then used to recover the energy stored in these resonant elements. This paper also explains the operation of the circuit cells and the many new passive lossless soft-switching power converters. A family of soft-switching boost converters is given as an example of the synthesis procedure. Experimental waveforms are also shown for a new soft-switching Cuk converter     

Family of Soft-Switching PWM Converters With Current Sharing in Switches

In this paper, a new family of soft-switching pulsewidth modulation (PWM) converters is introduced. In this family of converters, two switches operate out of phase and share the output current while providing soft-switching condition for each other. A buck converter, from this family of converters, is analyzed and its operating modes are discussed. The adoption of regular PWM control circuit to the proposed converters is presented. A prototype converter is implemented and its experimental results are illustrated.     

An Interleaved Boost Converter With Zero-Voltage Transition

This paper proposes a novel soft-switching interleaved boost converter composed of two shunted elementary boost conversion units and an auxiliary inductor. This converter is able to turn on both the active power switches at zero voltage to reduce their switching losses and evidently raise the conversion efficiency. Since the two parallel-operated elementary boost units are identical, operation analysis and design for the converter module becomes quite simple. A laboratory test circuit is built, and the circuit operation shows satisfactory agreement with the theoretical analysis. The experimental results show that this converter module performs very well with the output efficiency as high as 95%.     

Design and Application for PV Generation System Using a Soft-Switching Boost Converter With SARC

In order to improve the efficiency of energy conversion for a photovoltaic (PV) system, a soft-switching boost converter using a simple auxiliary resonant circuit, which is composed of an auxiliary switch, a diode, a resonant inductor, and a resonant capacitor, is adopted in this paper. The conventional boost converter decreases the efficiency because of hard switching, which generates losses when the switches are turned on/off. During this interval, all switches in the adopted circuit perform zero-current switching by the resonant inductor at turn-on, and zero-voltage switching by the resonant capacitor at turn-off. This switching pattern can reduce the switching losses, voltage and current stress of the switching device. Moreover, it is very easy to control. In this paper, we have analyzed the operational principles of the adopted soft-switching boost converter, and it is designed for PV generation system. Simulation and experimental results are presented to confirm the theoretical analysis.      

Reduction of power converter EMI emission using soft-switchingtechnique

Measurements of conducted and radiated electromagnetic interference (EMI) emission from hard-switched and soft-switched buck, boost, and flyback converters of similar power ratings are presented. Results indicate that EMI emission can be substantially reduced by using a soft-switching technique in power converters. Thus, the soft-switching technique provides a practical and useful solution to reduce EMI emission from switched-mode power circuits. A comparison of EMI emission on the three classes of converters is also included. The flyback converter is found to be the least EMC friendly among the converters tested     

Novel Family of PWM Soft-Single-Switched DC–DC Converters With Coupled Inductors

In this paper, a novel family of pulsewidth-modulation soft-single-switched dc–dc converters without high voltage and current stresses is described. These converters do not require any extra switch to achieve soft switching, which considerably simplifies the control circuit. In all converter family members, the switch is turned on under zero-current condition and is turned off at almost zero-voltage condition. From the proposed converter family, the boost topology is analyzed, and its operating modes are explained. The presented experimental results of a prototype boost converter confirm the theoretical analysis.      

Design and analysis of a proposed transformerless/non-isolated high-‎gain DC-DC converter for renewable energy applications

ABSTRACT

This paper proposes a transformerless/non-isolated, high-gain DC-DC converter required to increase low voltages in renewable energy applications. The converter topology uses only a single-switch with minimum voltage stress over the semiconductors. The design is obtained by integrating both the boost and the quadratic boost converter topology. Operating principles of the converter circuit topology are detailed, and the steady-state performance is analysed. The design results in lower switching voltage that significantly improves the efficiency of the controlled switches. The results obtained by computer simulation demonstrate that the high voltage gain is obtained at lower values of duty ratio with an efficiency of more than 94%. The merits of the proposed converter are given in comparison with other high-gain DC-DC converters. Finally, a laboratory model is built using the digital signal processor [dSPACE (DS-1104)] to verify the converter theory. The theoretical, simulation and experimental results that indicate the claimed converter performance and capability are given.     

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。     

Lossless passive soft-switching methods for inverters andamplifiers

This paper proposes lossless passive soft-switching methods for inverters developed from a synthesis procedure applicable to all pulsewidth modulation (PWM) converters. The lossless passive soft-switching converter properties and synthesis procedure are derived for inverters. Promising full-bridge and half-bridge soft-switching inverter examples are shown from the synthesis results. These include a new soft turn-on full bridge that contains only six components and a new soft turn-on and turn-off half bridge that contains 12 components. The voltage stress across the active switches can be easily maintained below 125% of V_bus. Additionally, no transformers are used for energy recovery, eliminating their associated diode stress and leakage inductance problems. The theoretical and experimental waveforms and analysis are given     

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     

Soft switching active snubbers for DC/DC converters

A soft-switching active snubber is proposed to reduce the turn-off losses of the insulated gate bipolar transistor (IGBT) in a buck power converter. The soft-switching snubber provides zero-voltage switching for the IGBT, thereby reducing its high turn-off losses due to the current tailing. The proposed snubber uses an auxiliary switch to discharge the snubber capacitor. This auxiliary switch also operates at zero-voltage and zero-current switching. The size of the auxiliary switch compared to the main switch makes this snubber a good alternative to the conventional snubber or even to passive low-loss snubbers. The use of the soft-switching active snubber permits the IGBT to operate at high frequencies with an improved RBSOA. In the experimental results reported for a 1 kW, 40 kHz prototype, combined switching/snubbing losses are reduced by 36% through the use of the active snubber compared to a conventional RCD snubber. The use of an active snubber allows recovery of part of the energy stored in the snubber capacitor during turn-off. The generic snubber cell for the buck power converter is generalized to support the common nonisolated DC/DC power converters (buck, boost, buck-boost, Cuk, sepic, zeta) as well as isolated DC/DC power converters (forward, flyback, Cuk, and sepic)     

Input impedance analysis of single-phase PFC converters

The input impedance of single-phase boost power factor corrected (PFC) AC-DC converters is modeled and analyzed in this paper. A large-signal model is presented for the input impedance which overcomes the limitations of traditional piece-wise linearized models. The model is valid at frequencies ranging from the crossover frequency of the output voltage loop to half the switching frequency of the converter. Experimental results from a boost single-phase PFC converter are provided to validate the model. Input characteristics of typical boost PFC converters, such as input impedance dipping, leading phase of the input current, and responses to distorted input voltages are studied by using the model. A simple compensation technique to reduce the dipping in the input impedance, thereby improving converter performance and minimizing the potential for undesirable interactions with the input filter or the ac source, is also presented.