三电平变换器PWM控制通态损耗分析

Analysis of Conduction Losses in Three-level Converter with PWM Control

为了进一步优化变换器的热设计,分析研究了电压源中点钳位式三电平变换器的通态损耗,并提供了分析多电平变换器通态损耗的思路:根据电流、电压关系确定器件导通规律,进而求出器件通态占空比,并在此基础上推导出用于分析计算的通态损耗表达式。由所推导的表达式对正弦脉宽调制和空间矢量脉宽调制下的三电平变换器通态损耗进行了分析比较,并得到一些有意义的结论。

For optimum thermal design consideration, the conduction losses for neutral-point-clamped （NPC）three -level PWM voltage source converter was investigated, and an effective and straightway conduction-loss-analysis method was presented. The conduction losses expressions are derived based on the knowledge of conduction devices, which are determined by the working condition, and the conduction duty cycle. This method can be utilized to calculate conduction losses for different PWM modulation strategies. Sinusoidal PWM （SPWM） and space vector PWM （SVPWM） techniques are discussed with the calculations for conduction losses in the tran- sistors, diodes and the control system. Some interesting conclusions can be come to according to the analysis and compare.