无锁相环三相DC/AC变流器直接功率预测控制

Predictive Direct Power Control of Three-phase DC/AC Converter Without Phase Locked Loop

以三相DC/AC变流器为研究对象,给出了一种无锁相环直接功率预测控制方法,能实现对并网功率的无差拍控制,并且为降低锁相环对控制性能的影响,实现无锁相环控制。根据采样控制导致的两拍延时,采样控制频率为载波频率两倍,精确计算得到下一拍的变流器状态量,然后针对给定功率参考值根据公式直接计算得到三相变流电路的输出。推导得到控制系统设定的频率与电网频率的偏差对所提出控制方法的性能没有影响,论证了无锁相环的可行性。最后构建了三相并网变流器Simulink仿真模型和实验样机,利用Simulink中的Embedded Coder模块实现控制系统仿真模型到DSP硬件控制系统C语言程序的转换,通过仿真和实验验证了控制方法的有效性。

A predictive direct power control method without the phase locked loop（PLL）is presented,the research object of which is the three-phase DC/AC converter.This method can achieve the deadbeat control of grid-connected power.In order to reduce the influence on the control performance by PLL,the method without PLL is realized.According to the two-beat delay resulting from the sampling control,the sampling frequency which is twice the carrier frequency is adopted to calculate the grid voltage,the grid-connected power and current after one cycle accurately.The output of the converter is calculated by the formula given in the paper.The deviation between the frequency set by the control system and the grid frequency has no influence on the performance of the control method proposed in this paper.The feasibility of the absence of phase locked loop（PLL）is demonstrated.The three-phase grid-connected converter simulation model and experimental prototype are built.The conversion from a control system simulation model into the C language program of DSP is realized by the Embedded Coder block of Simulink.The control method is validated and analyzed by simulation and experiment.