多电平直流链电力电子变压器控制策略研究

多电平直流链电力电子变压器(PET)中间级子模块拓扑包括半桥和双有源桥两部分。直流链两端电路不同的结构和控制策略会造成直流链电压的波动和不稳定。传统控制策略需要大量电流传感器,并且控制链路上的低通滤波器影响了系统的动态响应。文中提出了一种多电平直流链PET的控制策略,由串并联功率模块中的半桥电路稳定直流链总输出电压,由双有源桥电路实现直流链不同模块之间的均压。同时,所提控制策略只需要中压直流端口连接电感处的一个电流传感器,所有功率模块均不使用电流传感器,节省了系统的成本。仿真结果验证了所提控制策略的正确性和有效性。

Control strategies for the multi-level DC-link power electronic transformer

Different structures and control strategies will cause fluctuation and instability for DC-link voltage of the power electronic transformers. Traditional control strategy require a large number of current sensors, and the low-pass filter on the control link affects the dynamic response of the system. A control strategy for the multi-level DC-link power electronic transformer is proposed in this paper. The voltage sharing of DC link between power modules is realized by half-bridge circuit, and the current sharing of output current between modules is realized by DAB circuit. At the same time, the proposed control strategy only needs a current sensor at the inductance of the medium voltage DC port. All power modules do not use current sensors, which saves the cost of the system. The simulation results verify the correctness and effectiveness of the proposed control strategy.