一种适用于三电平逆变器的协调控制策略

A Coordinated Control Strategy for Three-level Inverter

针对中点箝位型三电平逆变器(NPC TLI)的中点电压和开关损耗问题,这里提出了一种适用于全调制度和全功率因数的多目标协调控制策略。TLI具有电流谐波小、开关应力低等优点,被广泛应用于中压大功率领域。首先,分析了TLI的工作原理和基于载波的非连续脉宽调制(CBDPWM)策略;其次,介绍了非连续脉宽调制(DPWM)策略的9种箝位模式及其对应的中点电流和开关损耗评价函数,提出了最小中点电压(NPV)波动和最小开关损耗的调制策略;再次,将两种调制策略进行函数化和归一化处理,建立了多目标协调控制函数模型;最后,通过实验验证了所提策略的可行性。

Aiming at midpoint voltage and switching loss problem of neutral point clamp three-level inverter(NPC TLI),a multi-objective coordinated control strategy suitable for full modulation degree and full power factor is proposed.TLIs have the advantages of small current harmonics and low switching stress,and are widely used in medium voltage and high power fields.Firstly,the working principle of the TLI and the carrier-based discontinuous pulse width modulation(CBDPWM) strategy are analyzed.Secondly,the nine clamp modes of discontinuous pulse width modulation(DPWM)strategy and their corresponding neutral point current and switching loss evaluation functions are introduced,and the modulation strategies of minimum neutral point voltage(NPV) fluctuation and minimum switching loss are proposed.Then,the two modulation strategies are functionalized and normalized,and a multi-objective coordinated control function model is established.Finally,the feasibility of the proposed strategy is verified experimentally.