脉冲直流环节三相逆变器零区效应与补偿

Zero Portion Effects and Compensation of Three Phase Inverters With the Pulsating DC-Link

为解决恒定直流环节三相逆变器中电解电容寿命较短的问题,采用一种基于混合脉宽调制策略的脉冲直流环节三相逆变器拓扑结构,但电解电容的取消会对最终输出电压造成不利影响;通过构建输出电压在三角载波周期内的平均数学模型与偏差电压在调制波周期内的傅里叶解析数学模型,对不同前后级载波频率差异、零区宽度和调制度下输出电压谐波性能、直流电压利用率和直流偏置的变化规律进行深入探究,进而基于时域仿真对输出电压的时变波形进行零区效应量化分析,最终基于输出电压平均数学模型,提出一种调制波分段补偿策略,并通过仿真与样机试验,验证了理论分析的正确性与补偿策略的可行性。

This paper presented a three phase inverter with the pulsating dc-link based on the hybrid modulation strategy. It relieved the need of dc-link electrolytic capacitors, reducing the volume and improving the lifetime. However, eliminating dc-link capacitors resulted in negative effects on output voltages. Then by establishing the average model of output voltages in a carrier cycle and the Fourier analytical model of deviation voltages in a modulation wave cycle, the harmonic distortion, efficiency of the dc voltage and the dc offset of output voltages were explored with different carrier frequency differences, zero portion widths and modulation indexes. And further quantitative analysis was carried out by the time-domain simulation method. Subsequently, a piecewise compensation strategy was proposed based on the average model, and the correctness of theory analysis and feasibility of the compensation strategy were verified by the simulation and experimental results.