开关电容有源箝位型多电平逆变器的多电压区间调制方法及电容电压控制策略

Multi-voltage Interval Modulation and Capacitor Voltage Control for Switched-capacitor Active-neutral-point-clamped Multi-level Converter

针对一种开关电容有源箝位型(switched-capacitor active-neutral-point-clamped,SC-ANPC)多电平逆变器的冗余开关状态数量不足,造成电容电压平衡困难的问题,提出一种适用于该拓扑结构的多电压区间调制方法及电容电压控制方法,解决了现有调制方法计算复杂及开关频率受限的问题。首先分析了逆变器的工作原理,根据逆变器开关状态,提出了三电平区间开关状态组合模型,并设计了满足开关电容电压静态平衡约束条件的多电压区间载波移相调制方法。由于满足静态平衡条件,开关电容电压体积和纹波得到了减少,并且开关管的载波之间只有简单的移相关系,工程实现简单。在此基础上,扩展到三相系统,建立了电容电压的纹波模型,提出了相应的电容电压控制方法,通过调节占空比实现开关电容电压控制,注入零序电压实现母线电容电压控制。通过仿真和实验验证所提调制方法、控制方法的可行性。

Aiming at the problem of an insufficient number of redundant switching states in a switched-capacitor active-neutral-point-clamped multilevel inverter,which causes difficulties in capacitor voltage balancing,a method of multi-voltage interval modulation and capacitor voltage control applicable to this topology are proposed.This new method also solves the problems of complicated calculation and limited switching frequency of the existing modulation methods.This paper first analyzes the operating principle of the inverter.It proposes a three-level interval switching state combination model according to the inverter switching states.Also,a method for multi-voltage interval carrier phase shift modulation that satisfies the static balancing constraints of the switched capacitor voltage is designed.Since the static balance condition is satisfied,the switched capacitor voltage volumes and ripples are reduced,and there is only a simple phase-shifting relationship between the carriers of the switch,which makes the engineering implementation simpler.On this basis,when this method is extended to the three-phase system,the ripple model of the capacitor voltage is established,and the corresponding capacitor voltage control method is proposed to realize the switched capacitor voltage control by adjusting the duty cycle and the bus capacitor voltage control through injecting the zero-sequence voltage.The feasibility of the proposed modulation and voltage control method is verified by simulations and experiments.