有源箝位五电平逆变器CHMPWM及悬浮电容电压控制

CHMPWM for active-neutral-point-clamped five-level converter and flying capacitor voltage control

针对降低功率器件的开关频率而带来电流谐波较大的问题,提出采用特殊设计的优化脉冲调制策略。通过深入研究五电平有源箝位(ANPC)逆变器电流谐波最小脉冲宽度调制(PWM)策略,设计一种基于遗传算法(GA)的优化脉冲调制开关角计算方案,该方案相比传统牛顿迭代法具有更好的电流谐波特性;对于五电平有源箝位逆变器存在的悬浮电容电压波动问题,提出一种基于冗余开关状态切换的悬浮电容电压滞环控制策略,通过合理分配冗余开关状态的作用时间,能够将悬浮电容电压有效稳定在参考值附近。仿真和实验结果验证了理论分析的正确性及所提控制方法的有效性。

It is necessary to decrease the switching frequency of the power devices in order to reduce the switching losses of the high-capacity inverters. However, it brings about large current harmonics, and special optimized PWM strategies need to be adopted. The current harmonic minimum pulse width modulation (PWM) strategy of five-level active neutral-point clamped (ANPC) inverter was studied in depth. A computing method of the optimized PWM switching angles based on the genetic algorithm (GA) was proposed. Compared with the traditional Newton iterative method, the proposed method can achieve better current harmonic characteristics. A hysteresis control scheme based on redundant switching states switching was proposed to restrain the fluctuation of the floating capacitor voltage of the five-level ANPC inverter. The floating capacitor voltage is effectively stabilized along its reference value by allocating the switching time of the redundant switching states reasonably. Finally, the validity of the theoretical analysis and effectiveness of the proposed control method are verified by simulation and experiments.