采用虚拟开关时间的五相逆变器PWM策略

PWM strategy with virtual switching time for five-phase inverter

针对五相电压源型逆变器的脉冲宽度调制控制技术,提出一种基于虚拟开关时间的电压调制方法。该方法利用虚拟开关时间的概念推导出一个时间自由度与逆变器各相实际开关时间的关系。在一个开关周期内,通过对该自由度及各相开关时间的合理安排,可以有效的提高系统的调制系数。该方法既简单易懂,又容易数字化实现,无需进行扇区和目标矢量位置的判断,避免了计算量大的问题;通过一个额外自由度的运用,可以方便地在各种类型的脉冲宽度调制间实现无缝切换,并且在一定程度上也揭示了载波型脉冲宽度调制和空间矢量脉冲宽度调制的内在联系。仿真结果验证了该方法的有效性。

The pulse width modulation （ PWM ） approach for five-phase voltage source inverter （VSI） is presented in this paper based on the concept of virtual switching time with a detailed explanation. The re- lationship between time degree of freedom and the actual inverter switching time of each phase is derived by using this concept. Through reasonable arrangement of the degree of freedom and switching time of each phase, the modulation factor in one switching cycle can be improved effectively. Various PWM schemes can be implemented with lower computational burden through this approach, as it＇ s easy to be understood and realized, and furthermore, a seamless change from one modulation scheme to another be- comes feasible. And to some extent, the internal relations of carrier-based PWM and space vector pulse width modulation （SVPWM） are also revealed. The proposed modulation strategy is proved to be effective through using numerical simulations.