Electronic step down (220/110 V) transformer using a new quantumseries resonant converter

A novel quantum series resonant converter (QSRC) topology for a pure sinewave 60 Hz AC chopper is proposed. It has three bidirectional switches and operates at high switching frequency with low switching loss. Bidirectional power flow is possible, and the switches can operate in either zero current switching (ZCS) mode or zero voltage switching (ZVS) mode by slight modification. The QSRC is thought to be suitable for such a system with fixed voltage conversion ratio. The proposed converter is applied to an electronic 220/110 V transformer. Detailed analyses and experimental results for 1 kVA are presented     

Composite soft switching configuration for inverters using bridge leg modules

The use of either lossless snubbers or resonant zero voltage switching (ZVS) and zero current switching (ZCS) techniques can increase efficiency and reduce electromagnetic interference (EMI) and noise of industrial power equipment at high switching frequencies. This paper presents an adaptive composite soft switching configuration which combines snubber functions and resonant ZCS circuits for switches in inverters using power bridge leg modules. Simulation and experimental results are included.     

Zero-Voltage Switching DC Link Single-Phase Pulsewidth-Modulated Voltage Source Inverter

A zero voltage switching (ZVS) dc link, single-phase, pulsewidth- modulated voltage source inverter (VSI) is proposed. Operating principle and various operating intervals of the converter are presented and analyzed. Design considerations are discussed and a design example of a 300 VA VSI is given. Experimental results from a laboratory prototype model are presented. ZVS is achieved for forward and reverse power flow, without increasing the voltage stress on the inverter devices.     

An improved self-resonant PWM forward converter

This paper presents a forward converter with a nondissipative cell which provides a soft switching converter operation. This approach is based on the principle of self-resonance, that is: an auxiliary voltage source feeds the resonant circuit, charging a capacitor which provides the condition for zero voltage switching (ZVS) turn on and turn off of the switches. The complete operating principle, relevant equations, simulation, and experimental results are presented     

Analysis of Two Continuous Control Regions of Conventional Phase Shift and Transition Phase Shift for Induction Heating Inverter under ZVS and NON-ZVS Operation

This paper proposes an analysis of two continuous control regions of conventional phase shift and transition phase shift for a full-bridge series resonant inverter operating under zero voltage switching (ZVS) and nonzero voltage switching (NON-ZVS) conditions with the load of induction heating. A number of circuit operations for the cases of conventional phase-shift and transition phase-shift control regions under ZVS and NON-ZVS conditions are analyzed first. Various voltage and current equations of the operating circuits are then obtained and used for calculation of the waveforms with the aid of the MATLAB program. The calculated waveforms make possible the consideration of some important circuit parameters that are used to determine ZVS or NON-ZVS conditions. The theoretical results and the proposed method are also verified by experiments, using a prototype test set in our laboratory.      

Single-stage electronic ballast with high-power factor

This article proposes a single-stage electronic ballast circuit with high-power factor. The proposed circuit was derived by sharing the switches of the power factor correction (PFC) and the half-bridge LCC resonant inverter. This integration of switches forms the proposed single-stage electronic ballast, which provides an almost unity power factor and a ripple-free input current by using a coupled inductor without increasing the voltage stress. In addition, it realises zero-voltage-switching (ZVS) by employing the self-oscillation technique. The saturable transformer constituting the self-oscillating drive limits the lamp current and dominates the switching frequency of the ballast. Therefore, the proposed single-stage ballast has the advantage of high-power factor, high efficiency, low cost and high reliability. Steady-state analysis of the PFC and the half-bridge LCC resonant inverter are described. The results of experiments performed using a 30 W fluorescent lamp are also presented to confirm the performance of the proposed ballast.     

High-power-factor electronic ballast with constant DC-link voltage

This paper presents a high-power-factor (HPF) electronic ballast based on a single power processing stage with constant DC-link voltage. The switching frequency is controlled to maintain the DC-link voltage and the voltage across the switches constant, independently of changes in the AC-input voltage. This control method assures zero-voltage switching (ZVS) for the specified AC-input-voltage range. Besides, with an appropriate design of the fluorescent lamps' drive circuit, the lamps' power can be kept close to the rated value. The power-factor-correction (PFC) stage is formed by a boost power converter operating in the discontinuous conduction mode, which naturally provides HPF to the utility line. The fluorescent lamps are driven by an unmodulated sine-wave current generated from an LC parallel resonant power converter which operates above the resonant frequency to perform ZVS. Theoretical analysis and experimental results are presented for two series-connected 40 W fluorescent lamps operating from 127 V -15% to +10% 60 Hz utility line. The switching frequency is changed from 25 to 45 kHz to maintain the DC-link voltage regulated at 410 V, which leads to a constant output power. The experimental results confirm the high efficiency and HPF of this electronic ballast     

Zero-voltage switching for three-level capacitor clamping inverter

A zero-voltage switching (ZVS) scheme for a three-level capacitor clamping inverter based on the true pulsewidth modulation (PWM) pole is proposed in this paper. With this scheme, the main switches work with ZVS through the assistance of a small rating zero current switching (ZCS) lossless auxiliary circuitry without imposing any voltage/current spikes on the main devices or any extra control complexities. Consequently, a three-level capacitor clamping inverter system can operate at a promoted switching frequency and becomes more eligible to be considered for high-power advanced applications, for example, in high-speed drives or power active filter areas. In this paper, the main circuit operation issues as regards the clamping voltage stability, damping capacitor stress, and output voltage spectrum are shortly reviewed first, after which the commutation principle, auxiliary circuitry stress analysis, and auxiliary circuitry designing methodology are presented in detail. Experimental results from a 700 V supply 3 kW half-bridge three-level capacitor clamping inverter are demonstrated which conform well to the proposal     

中小功率三相高频节能型谐振极逆变器

作为中小功率发电系统重要环节的三相逆变器的开关频率增大时,开关损耗也显著增大,不利于节能。为实现中小功率三相逆变器的高频化和节能化,提出了一种三相零电压开关谐振极逆变器拓扑结构.当桥臂上的辅助谐振电路处于工作状态时,开关器件并联的电容的电压能周期性变化到零,使开关器件完成零电压软切换,这有利于高频金属氧化物半导体场效应晶体管（Metal Oxide Semiconductor Field Effect Transistor,MOSFET）作为逆变器的开关器件.分析了电路的工作流程,实验结果表明开关器件处于零电压软切换.因此,该拓扑结构对于研发高性能的中小功率三相逆变器具有参考价值.     

High-efficiency low-stress electronic dimming ballast for multiplefluorescent lamps

An electronic dimming ballast with a lead-lag tank operation (LLTO) having the properties of high efficiency and low stress is introduced in this paper. The ballast is configured with a voltage-fed half-bridge series-resonant parallel-loaded inverter (SRPLI) acting as a lamp driver. It is loaded with resonant tanks which are designed and operated to be capacitive and inductive to theoretically achieve both zero-voltage switching (ZVS) and zero current switching (ZCS) and to eliminate the reactive current circulating through the switches, resulting in low switching and conduction losses. Moreover, the merit of a successive lamp ignition can be attained with the proposed operation scheme so that current stress imposed on the switches can be reduced. With the plasma model of fluorescent lamps, the analysis, operating principle, and dimming control strategy of the electronic ballast are described in detail. On the other hand, the limitations of the proposed scheme are pointed out. Computer simulation results and experimental measurements are used to verify the theoretical prediction and analytical discussion     

Resonant link bidirectional power converter. I. Resonant circuit

This paper proposes a novel resonant circuit capable of PWM operation with zero switching losses. The resonant circuit is aimed at providing zero voltage intervals in the DC link of the PWM converter during the required converter device switching periods, and it gives minimum DC bus voltage stresses and minimum peak resonant current. It requires only two additional switches compared to a conventional PWM converter. It is observed that the resonant circuit guarantees the soft switching of all the switching power devices of converters including the switches for resonant operation. Simulation results and experimental results are presented to verify the operating principles     

Parallel resonant DC link circuit-a novel zero switching losstopology with minimum voltage stresses

A parallel resonant DC link (PRDCL) circuit topology is proposed as an approach to realizing zero switching loss DC-AC high switching frequency power conversion. The proposed circuit is used as an interface between the DC voltage supply and a voltage source pulse width modulated (PWM) inverter to provide a short zero voltage period in the DC link of the inverter to allow zero voltage switchings to take place in the PWM inverter. The peak voltage stress on the PWM inverter switches is limited to the DC supply voltage. Another significant advantage of the circuit is that the inverter can be controlled by the conventional PWM strategy. The proposed circuit is systematically analyzed and its operation principle is explained. Design considerations and design formulas are presented. A complete zero voltage switching DC-AC system consisting of the proposed circuit and a PWM inverter was simulated on a computer     

The novel resonant DC link three-level soft-switching inverter

ABSTRACT

In the paper, the novel topology of the resonant DC link three-level soft-switching inverter is proposed to reduce switching losses and improve the efficiency of three-level inverter at high switching frequency. Symmetrical auxiliary resonant circuits are set in the DC link of three-level hard-switching inverter. Moreover, the terminal voltage of the resonant capacitors between the DC buses periodically drops to zero via the resonance of auxiliary circuits. Furthermore, under such condition, the main switches of the three-level inverter would be operated, in order to achieve zero-voltage switching. Based on the equivalent circuits in different operating modes, the paper analyses the working process of the soft-switching inverter in detail. In addition, a 3 kW laboratory prototype of resonant DC link three-phase three-level soft-switching inverter is built. The experimental results show that the main switches and auxiliary switches of the inverter are operated under soft-switching conditions, and the efficiency is significantly improved compared with the three-level hard-switching inverter. Therefore, the proposed topology can effectively reduce switching losses and prove to be more practical in engineering.     

New zero voltage switching DC converter with flying capacitors

A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at V_in/2. Therefore, power metal–oxide–semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.     

A Novel Control Method for Piezoelectric-Transformer Based Power Supplies Assuring Zero-Voltage-Switching Operation

In this paper, a new control strategy that allows zero-voltage-switching (ZVS) operation of power converters using piezoelectric transformers (PTs) is proposed. The control circuit operates in a closed loop by measuring the phase between the PTs resonant current and the switching pattern and adjusting the switching frequency to the optimum value so that ZVS operation is assured. An innovative nonlinear regulator based on an analog multiplexer is presented. The regulator automatically swaps the signs of the sensed signal and the reference signal to allow generation of the adequate control action. A laboratory prototype for a 6 W resonant inverter was tested; obtained experimental results are also shown.     

Modular design of soft-switching circuits for two-level and three-level inverters

This paper presents a negative-bus auxiliary resonant circuit (NBARC) and novel mirror symmetrical pair of resonant link modules for soft commutation of two-level and three-level inverters. The NBARC topology reduces the power device counts and requires low device power ratings. While the basic NBARC resonant circuit is conceived and analyzed for zero-voltage switching (ZVS) of two-level inverters, the topology and modular design approach are extended to form a pinched-link resonant stage of ZVS for three-level inverters using mirror-symmetrical pair of resonant modules. The circuit is also designed as an optional module that can be attached to a standard inverter bridge and converted into a soft-switched inverter. Experimental results verify our circuit analysis and implementation.     

Analysis and implementation of active clamp SEPIC converter with synchronous rectifier

An active clamp SEPIC converter with synchronous rectifier is presented to achieve zero voltage switching (ZVS). The active clamp circuit is adopted in the proposed converter to absorb the energy stored in the leakage inductance of the transformer and limit the peak voltage stress on the switching devices. The resonance during the transition interval between the switching devices will help the power switches to turn on at ZVS. Therefore, the switching losses of switches are effectively reduced. The synchronous rectifier is used at the secondary side of the transformer to further reduce the conduction loss. The principle of operation and the steady-state analysis of the proposed converter are presented. Finally, the experimental results taken from a laboratory prototype with 240 W (12V/20A) rated power are presented to verify the effectiveness of the proposed converter.     

Analysis and design of class E isolated DC/DC converter using classE low dv/dt PWM synchronous rectifier

A class E isolated DC/DC power converter for regulating the output voltage at a fixed switching frequency is presented, analyzed and experimentally verified. It consists of class E series-resonant inverter, high-frequency transformer and class E low dv/dt pulse width modulation (PWM) synchronous rectifier. By controlling the conduction time of the controlled switch in the rectifier, high-frequency AC current is rectified and the output voltage can be controlled at the same time. The zero voltage switching (ZVS) condition of all switches can be maintained from full-loaded to open-loaded. The theoretical predictions were in good agreement with the experimental measurements and the maximum efficiency measured at a switching frequency of 1 MHz was 91.2%     

Quasi-parallel resonant DC link inverter with improved PWMcapability

A quasi-parallel resonant DC-link (QPRDCL) circuit with improved PWM capability is proposed for the zero voltage switching (ZVS) three phase PWM inverter. The circuit has minimum voltage stresses and improved PWM capability due to the flexible selectability of the on/off instants of the resonant link     

具有软开关功能的三相谐振直流环节逆变器

为实现三相逆变器节能运行,提出一种具有软开关功能的三相谐振直流环节逆变器.直流侧的辅助谐振电路将参与换流过程,使直流环节电压在桥臂上的主开关动作之前变化到零,主开关能完成零电压软切换动作,通过降低开关损耗来实现逆变器节能运行.分析了1个开关周期内的电路工作流程.实验结果显示开关器件动作时处于软切换.因此,该辅助谐振电路结构对于研发节能型三相逆变器具有参考价值.