三电平NPC变流器虚拟空间矢量调制策略与载波调制策略的内在关系研究

Research on Internal Relation Between Virtual Space Vector Pulse Width Modulation Strategy and Carrier Sinusoidal Pulse Width Modulation Strategy for Three-Level Neutral Point Clamped Converter

分析了虚拟空间矢量调制(virtual space vector pulse width modulation,VSVPWM)策略的基本原理,推导了三电平VSVPWM策略与单相双调制波三电平正弦脉冲宽度调制(sinusoidal pulse width modulation,SPWM)策略的内在联系,建立了两者间的调制波等效关系。应用调制波等效关系分析了VSVPWM策略的输出电压总谐波畸变率(total harmonic distortion,THD)、直流电压利用率和关器件损耗。后,提出了基于调制波等效关系的三电平VSVPWM快速实现方案。仿真和实验结果验证了理论分析的正确性。

In the modulation strategies for three-level NPC converter, neutral point voltage control under the entire modulation index and full power factor can be achieved by virtual space vector pulse width modulation （VSVPWM） strategy. In this paper the basic principle of VSVPWM is analyzed, then the intemal relation between three-level VSVPWM strategy and single-phase dual modulation based three-level sinusoidal pulse width modulation （SPWM） strategy is derived and the modulation-wave equivalence between the two modulation strategies is established. Using the established modulation-wave equivalent relation, the total harmonic distortion （THD） of output voltage, DC voltage utilization rate and switch device losses under VSVPWM strategy are analyzed. Finally, a fast implementation of three-level VSVPWM strategy based on modulation-wave equivalence is proposed. The correctness of the theoretical analysis is verified by both results from simulation and experiments.