高频隔离微网互联变流器控制系统的设计与实现

Design and Implementation of Control System of High-Frequency Isolated Interconnection Converter of Microgrids

高性能的控制系统是交直流混合微网高频隔离互联变流器可靠运行的先决条件。由于高频隔离互联变流器拓扑复杂,开关器件数量多,常规控制方式无法满足其控制要求。为了解决这一问题,基于DSP和CPLD设计了一种高频隔离交直流混合微网互联变流器的控制系统。DSP在控制系统中负责信号采样、处理、控制环路补偿以及控制策略的PWM实现。CPLD负责过渡过程中开关器件的电压电流特征监测。通过反馈调节控制,实现高频隔离变压器磁芯偏置抑制和交流微网侧波形的控制。根据控制信号和交流侧换流过程的模态转换,实现变流器的零电流关断软开关。最后实现了设计方案并进行了实验验证,实验结果表明了所设计的控制系统的可行性。

Control system with high performance is indispensable for high-frequency isolated interconnection converter for AC/DC hybrid microgrid.Traditional control can’t meet the requirement because of the complex topology and the multitudinous switches of it.In order to solve the problem,a control system based on DSP and CPLD for the interconnection converter is designed.In the control system,the DSP is in charge of signal sampling,processing,control loop compensation,and PWM strategy implementation,while the CPLD is in charge of monitoring the characteristic of the voltage and current of the switching devices during the transient process.The control system reduces the flux bias in the core of the transformer and regulates the current waveforms at the AC side by feedback control.It also realizes zero current turning-off soft-switching of the converter according to the control signals and the transient modes of the switching device.Finally,a prototype is implemented and tested.The experimental results verify the feasibility of the proposed control system.