一种带约束的电压空间矢量脉宽调制方法

Abstract

为解决传统调制方法中的最小脉宽问题,提出了一种带约束的电压空间矢量脉宽调制(SPACE VECTOr PulSE WIdTH MOdulATIOn,SVPWM)方法。首先,建立新的三相桥臂坐标,取消了扇区的划分和判断;其次,将基本电压空间矢量由8个减小为3个,并将其作用时间与三相桥臂的导通时间一一对应;再次,通过增加约束条件,将传统SVPWM方法的调制过程及其结果离散化,从而避免了窄脉宽的出现;最后,给出了一种快速的计算策略,其计算量仅与SVPWM方法一个扇区的计算量基本相同。相对于SVPWM方法,所提方法调制的基波与杂波在频谱上的分布更清晰,低次谐波较少,有利于进行低通滤波处理,更适合较高电压和较大电流的逆变要求。仿真及实验结果均验证了该方法的可行性。

To solve the problem of the minimum pulse width in traditional modulation methods, a space vector pulse width modulation(SVPWM) method with constraints is proposed.Firstly, a three-phase bridge-arm coordinate is established to cancel the traditional sector division and the judgment; secondly, the number of basic voltage space vectors is reduced from 8 to 3, and their actuation durations correspond to the on-times of three-phase bridge-arms respectively; thirdly, by means of adding constraint conditions the modulation process of traditional SVPWM and modulation results are discretized to prevent the appearance of narrow pulse width; finally a fast computational strategy is given and its calculated amount is basically same as to the calculated amount for one sector by SVPWM method.Relative to SVPWM method, the distribution of the fundamental wave and clutters modulated by the proposed method on the frequency spectrum is more clear and there are less low-order harmonics, so it is favorable to implement low-pass filtering, thus the proposed method is more suitable for PV inverters with higher voltage and larger current.The feasibility of the proposed method is verified by results of simulation and experiments.