一种DNPC三电平PFC整流器的控制方法

固态变压器是一种采用高频隔离电路实现中压交流到低压直流的功率变换装置,具备高效率、高功率密度、模块化和易扩展等优点,在高耗能的直流工业应用中越来越具备吸引力。SST的模块可采用三电平单向功率因数校正电路,较传统全桥拓扑相比具备更高的电压承受能力,成本较双向拓扑更低。该文提出一种适用于三电平PFC变换器的控制方法,可消除工频中点电压波动,减少中间直流链接(dc-link)电容至传统的1/3,大幅降低体积,可简化器件选型,降低成本。提出一种基于FPGA控制芯片的实现方法。在10 kW三电平模块和单相三模块级联的SST样机上对该文提出的方案进行实验验证。

Solid State Transformer(SST)is a power conversion device for converting the medium voltage alternating current(MVAC)into the low voltage alternating current(LVAC).SST has advantages of high efficiency and power density,modularity and scalability,and becomes more attractive to high energy consumption industry.Three-level unidirectional power factor correction(PFC)rectifier can be used as the module of the SST system.It can take higher voltage stress than conventional full-bridge topology and has lower cost than bidirectional topology.This article proposed a control method which can almost eliminate the neutral-point(NP)voltage ripple and can save up to 2/3 dc-link capacitor volume,compared with the conventional method.Furthermore,the proposed control method can decrease the cost of switching devices.A simple implementation method based on FPGA controller is proposed.The proposed methods are experimentally verified on a 10 kW silicon carbide based three-level converter cell and a single-phase multi-cell SST prototype.