高效率单相全桥软开关整流器

单相全桥整流器工作在硬开关状态时,随着开关频率和输出功率的增大,开关损耗会显著增大,影响整流器效率的提高.为解决这一问题,提出了一种单相全桥软开关整流器,在整流器处于死区状态时,将要开通的主开关并联的谐振电容的电压能减小至零,主开关动作时能完成零电压软切换,双向辅助开关动作时能完成零电流软切换.分析了整流器的换流过程,实验结果表明主开关和辅助开关完成了软切换动作.因此,该单相全桥软开关整流器在高开关频率下能实现高效率运行.     

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.     

单相全桥三电平节能逆变器

随着开关频率的提高,单相全桥逆变器处于硬开关切换时的开关损耗也会明显增大,将导致逆变器处于低效率运行.为解决这一问题,提出了一种单相全桥三电平节能逆变器.通过设置辅助换流电路,利用谐振使主开关并联的电容的电压下降到零,主开关可实现零电压切换,而且在换流过程中,两组双向辅助开关可分别实现零电压切换和零电流切换.分析了电路的工作状态,实验结果表明主开关和辅助开关都能实现软切换.因此该单相全桥三电平逆变器可实现高效率运行.     

中小功率三相高频节能型谐振直流环节逆变器

为使中小功率三相逆变器实现在高开关频率下的节能运行,首次提出了一种新型三相谐振直流环节逆变器拓扑结构.设置在逆变器直流环节的辅助电路参与换流过程时,桥臂输入端的直流环节电压能周期性形成零电压状态,主开关和辅助开关都能完成零电压软切换.在高频金属氧化物半导体场效应晶体管（Metal Oxide Semiconductor Field Effect Transistor,MOSFET）作为该逆变器的开关器件时,实现零电压软切换能消除MOSFET的容性开通损耗,有利于优化逆变器效率.文中分析了电路的工作流程.2.5kW样机上的实验结果表明开关器件都处于零电压软切换.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.     

节能型三相桥式零电流开关整流器

为使三相桥式整流器实现节能运行,提出了一种节能型三相桥式零电流开关整流器拓扑结构,在各相桥臂上的辅助谐振电路处于工作状态时,整流器的开关器件能完成零电流软关断.三相桥式整流器通常以绝缘栅双极型晶体管（Insulated Gate Bipolar Transistor,IGBT）作为开关器件,实现零电流软关断能消除IGBT拖尾电流产生的关断损耗.分析了电路工作过程,在三相3kW样机上的实验结果表明开关器件实现了零电流软切换.因此,该拓扑结构可实现以IGBT作为开关器件的三相桥式整流器的节能运行.     

高效率三相谐振极逆变器

为优化三相逆变器的性能,提出了一种高效率三相谐振极逆变器.在各相桥臂上增设的辅助谐振电路参与逆变器的换流过程时,桥臂上的各主开关并联的谐振电容的电压能周期性形成零状态,使主开关能完成零电压软切换,而且辅助谐振电路中的各开关器件也能完成零电流软开通和零电压软关断.开关器件实现软切换能降低开关损耗,从而使逆变器实现高效率运行.文中分析了电路的工作流程.3kW样机上的实验结果表明主开关和辅助开关都处于软切换.因此,该拓扑结构对于研发高性能三相逆变器具有借鉴价值.     

辅助电路与主开关并联的单相全桥节能逆变器

为了改善逆变器的性能,提出了一种辅助电路与主开关并联的单相全桥节能逆变器.逆变器采用受限单极式正弦脉宽调制（Sinusoidal Pulse Width Modulation,SPWM）方法,在每个开关周期,只需要控制1个主开关和1个辅助开关的切换,辅助开关可以采用固定占空比控制,而且不需要设定谐振电流阈值来控制辅助开关.在每个开关周期的换流过程中,需要切换的主开关所并联的谐振电容的电压能变化到零,主开关能实现零电压软开通.辅助电路中无器件直接串联在直流母线上,可有效降低辅助电路通态损耗.分析了电路工作原理,实验结果表明主开关和辅助开关都实现了软切换.因此该拓扑能有效降低开关损耗和提高逆变器效率.     

节能型谐振直流环节逆变器

为改善逆变器的运行效率,提出了一种节能型三相谐振直流环节软开关逆变电路,在直流环节增设了辅助电路.当主开关需要切换时,提前使辅助电路进入谐振状态,将直流环节电压变化到零,保证主开关完成零电压软切换,并且辅助开关也能完成软切换.通过控制辅助开关切换的间隔时间来调节直流环节电压保持为零的时间,使逆变器能根据需要来调整脉宽调制策略.详细说明了电路的工作过程.实验结果表明逆变器主开关和辅助开关能完成软切换.因此,该拓扑结构对于研发高性能谐振直流环节逆变器具有借鉴意义.     

变压器辅助换流的三相节能型谐振极逆变器

在谐振极软开关逆变器辅助电路的换流过程中,为避免剩磁通的累积导致变压器铁心饱和,提出了一种变压器辅助换流的三相节能型谐振极逆变器的拓扑结构,在二极管反向阻断的作用下,变压器的磁化电流无法形成稳态环流,从而使变压器中的能量全部向负载转移,磁化电流最终变化到零,实现了变压器的去磁复位.此外,逆变器的主开关和辅助开关可以分别完成零电压软切换和零电流软切换.分析了电路的换流过程.实验结果表明逆变器的开关器件完成了软切换,变压器磁化电流能减小到零.该拓扑结构对于研发高性能谐振极逆变器具有一定的参考价值.     

新型单相软开关AC-DC-AC变换器

为改善单相AC-DC-AC变换器的性能,提出了一种单相谐振直流环节零电压开关AC-DC-AC功率变换器拓扑结构,由图腾柱式单相整流器,位于直流环节的辅助谐振电路和单相全桥逆变器组成.利用同一组辅助电路能分别将整流器输出端电压和逆变器输入端电压变化到零,使整流器和逆变器桥臂上的开关器件分别实现零电压切换.分析了电路的工作流程,在1.2kW样机上的实验结果表明开关器件完成了软切换.该拓扑结构对于研发节能型单相AC-DC-AC变换器具有借鉴意义.     

Analysis, designing, and experimentation of a transformer-assistedPWM zero-voltage switching pole inverter

This paper proposes a transformer-assisted pulsewidth modulation (PWM) zero-voltage switching pole inverter. As the auxiliary-resonant-commutated pole inverter (ARCPI), the proposal guarantees zero-voltage switching of the main switch and zero-current switching of the auxiliary switch, with a small power auxiliary circuit and full PWM capability. In particular, problems outstanding with the ARCPI such as control complexity, auxiliary switch protection, and center-tap potential variation, etc., are solved in the proposal. The commutation process is discussed step by step in the paper. A detailed analysis for the auxiliary circuit with regard to commutation duration/duty-cycle limitation, auxiliary switch peak current/RMS current, resonant capacitor RMS current, as well as pole output voltage loss are presented afterwards. A design methodology for the auxiliary circuit is recommended based on the analysis. The proposal is experimentally verified with a 4.25 kW half-bridge inverter prototype     

具有低能耗辅助电路的并联谐振直流环节逆变器

为提高逆变器的转换效率,提出了一种具有低能耗辅助谐振电路的并联谐振直流环节逆变器.在传统硬开关逆变器的直流环节添加辅助谐振电路,使直流母线电压周期性地归零,实现逆变桥主开关器件的零电压开关,而且辅助开关器件也可以实现零电压关断和零电流开通.此外,其辅助谐振电路只有一个辅助开关器件,控制简单;辅助开关和谐振元件都位于直流母线的并联支路上,有利于降低辅助谐振电路的能耗.对其工作原理进行分析,给出不同工作模式下的等效电路图和软开关的实现条件.制作一个5kW的实验样机,通过实验结果验证该软开关逆变器的有效性.     

A novel ZCS-PWM power-factor preregulator with reduced conduction losses

This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Nine transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 50 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.3% and power factor over 0.99 has been measured. Analysis, design, and the control circuitry are also presented in this paper.     

The three-phase resonant DC link inverter with soft-switching function

ABSTRACT

In order to realise the energy-saving operation of the three-phase inverter, a three-phase resonant DC link inverter with soft-switching function is proposed. The auxiliary resonant circuit on the DC side participates in the commutation process, so that the DC link voltage can change to zero before the main switch on the bridge arm is switched. Therefore, the main switch can complete the zero-voltage soft-switching and realise the energy-saving operation of the inverter by reducing the switching power loss. The circuit workflow and parameter design rules in each switching period are analysed. As indicated from the experimental results, the switching device is in the soft-switching state when it is switched, and when the output power reaches the rated value of 2.5 kW, the efficiency of the prototype is 98.4%, which is higher than that of the same type of soft-switching inverters. Thus, the auxiliary resonant circuit structure has reference value for the research and development of energy-saving three-phase inverters.     

A new single-phase ZCS-PWM boost rectifier with high power factor and low conduction losses

This paper proposes a new single-phase high-power-factor rectifier, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the active switches and zero-voltage switching (ZVS) in the passive switches. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved because of the following reasons: 1) the circulating current for the soft switching flows only through the auxiliary circuit; 2) a minimum number of switching devices are involved in the circulating current path; and 3) the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM-switch model is used to predict the system performance. A prototype rated at 1 kW, operating at 60 kHz, with an input alternating current voltage of 220 V/sub rms/ and an output voltage of 400 V/sub dc/, has been implemented in laboratory. An efficiency of 98.3% and a power factor over 0.99 have been measured. Analysis, design, and the control circuitry are also presented in this paper.