统一空间矢量PWM快速算法分析

根据SVPWM和载波PWM的内在关系,提出了一种三相逆变器统一SVPWM快速算法.该算法直接利用三相参考电压瞬时值计算PWM信号的开关状态切换时间,不需进行坐标变换、三角函数运算、扇区判断和有效矢量作用时间的计算,因此更易于各种SVPWM方法的数字化实现.实验结果证明了统一SVPWM快速算法的正确有效性.最后,对各种SVPWM方法的电压谐波特性进行对比分析的结果表明当调制比较大时,从谐波特性和开关损耗两方面综合考虑不连续SVPWM的性能较好.

The Analysis of the Unified SVPWM Fast Algorithm

A unified SVPWM fast algorithm, which is suitable for digitalization of all SVPWM strategies, is proposed according to the relationship between carrier-based PWM and SVPWM methods. The proposed algorithm is very simple and can be more easily implemented with a microprocessor because it calculates the actual gating times based on infant values of the three-phase reference voltages, with no need of complex coordinate transformations, trigonometric function calculations, sector number identification, and the recombination of actual gating times. The experimental results verify that the unified SVPWM is effective. At last, the voltage harmonic characteristics of different SVPWM methods is investigated. It is shown that discontinuous SVPWM strategies in the high modulation range have superior performance in view of the switching losses and harmonic characteristics.