基于三电平拓扑的电力电子变压器研究

Research on Power Electronic Transformer Based on Three-level Topology

提出一种改进的基于三电平拓扑的电力电子变压器(PET)。输入级、隔离级与输出级结构分别采用二极管箝位式三电平PWM整流器、零电压开关半桥三电平DC/DC变换器和两电平逆变器。与两电平PET相比,可在有效提高输入电压等级的同时降低开关损耗。针对变压器各环节结构特点设计了控制方案,并在配电系统环境下对其进行了建模和仿真。仿真结果表明,在稳态运行及电源波动、负载投切等动态运行条件下,三电平PET均能保持初、次级良好的电压电流波形,且能维持输出电压恒定,有效抑制了电网与负载的扰动,实现了良好的电能质量调节。

An improved power electronic transformer（PET） based on the three-level topology is proposed.The input stage, isolation stage and output stage use diode-clamped three-level PWM rectifier, zero-voltage-switching half-bridge three-level DC/DC converter and two-level inverter respectively.Compared with traditional two-level PET,the three- level PET can increase the rated input voltage and reduce losses of the switch devices.The control scheme of each stage is proposed for the structural features.Then modeling and simulation are made in the distribution system.Simu- lation results show that the three-level PET can not only guarantee good voltage and current waveforms in both pri- mary and secondary sides but also maintain a constant output voltage in the condition of steady-state operation and dynamic operation such as power supply fluctuation and load swithing.As a result,it can suppress the disturbances from grid and load effectively and achieve a good power quality regulation.