混合导通模式三相三电平VIENNA整流器控制策略

摘要

对三相三电平VIENNA型整流器进行物理解耦,进而分析单相三电平整流电路分别在连续和断续导通模式下的数学模型,针对该拓扑结构提出了一种适合用于混合导通模式的前馈控制策略。定参数电流环仅适用于一个电流工作模式,出现混合导通模式时,其控制效果很差。而在电流控制环中引入前馈,将理论上想要的占空比叠加在原电流环的输出端,新的控制环便能适应不同电流工作模式,从而大大降低电流总谐波失真度（THDi）。最后通过5kW三相实验样机,验证了该控制策略的可行性和有效性,在混合导通模式满载时的功率因数（PF）接近于1。%In this paper,three-phase three-level VIENNA rectifier is decoupled in topology.By analyzing of single-phase three-level rectifier operating in continuous and discontinuous conduction mode,an improved control method based on feedforward is proposed to achieve unit power factor(PF) and reduce the harmonic of the input current in mixed conduction mode(MCM).The problem of parameters conflicted in different modes is solved by adding the desired duty ratio to the output of original current-loop.So the improved current-loop could automatically switch between continuous and discontinuous conduction mode.Finally,an experimental prototype of 5kW is built to verify the feasibility of this strategy.The PF value is close to unity at full load when the converter operates at MCM and the total harmonic distortion of input-current(THDi) is significantly reduced.