基于DSP的微逆变器双频率控制方法及实现

传统交错反激微逆变器原边电流峰值与变压器体积、损耗较大。针对此问题,提出了一种基于原边峰值电流控制且电感电流断续模式(DCM)的双频率控制策略。推导了DCM模式下的参考电流表达式,并在此基础上,详细分析了双频率控制策略中开关频率切换点的选取原则,推导了其选取表达式。该策略可根据负载大小变化自动调节开关频率,在减小峰值电流的同时最大程度上减少开关次数,减小开关损耗。最后,通过PSIM仿真分析验证了设计的有效性,并研制出了以数字信号处理器(DSP)为核心控制器的实验平台。实验结果表明,该控制策略在减小原边电流峰值的同时能保证系统效率并实现较小的并网电流谐波畸变率(THD)。

Dual Frequency Control Method and Implementation of Micro Inverter Based on DSP

The peak value of the primary side current, the volume and the loss of the transformer in the conve-ntional interleaved flyback inverters are relatively large. To solve these problems, an dual frequency control strategy based on the primary peak current control and the inductor discontinuous current mode(DCM) was proposed. First, the expression of reference current in DCM mode was derived. On this basis, the selection principle of switching frequency switching point in dual frequency control strategy was analyzed in detail, and the expression of selection was derived. This method can automatically adjust the switching frequency according to the change of the load size. Then the number of switches is reduced and the switching loss is reduced to the maximum extent. Finally, the validity of the design is verified by PSIM simulation analysis, and an experimental platform with a digital signal processor(DSP) as the core controller is developed. The experimental results show that the control strategy can reduce the peak value of the primary current and ensure the system efficiency, achieve a lower current harmonic distortion rate(THD).