Abstract：With the increase of the output voltage and power level of the cascaded H-bridge (CHB) multilevel inverter, it is of great significance to increase the utilization ratio of DC side voltage under carrier phase shift pulse width modulation (CPS-PWM) strategy and to improve the poor harmonic performance in low-key system. By analyzing the principle and output voltage characteristics of Sinusoidal pulse width modulation (SPWM) and trapezoid wave pulse width modulation (TPWM), an improved CPS-PWM strategy based on the control of carrier freedom is proposed. According to the shape freedom of phase-shifting carrier, this strategy uses the improved multi-carrier instead of triangle carrier in original CPS-SPWM for modulation, which can significantly improve the DC voltage utilization of output voltage. This strategy can reduce the total distortion rate (THD) of the output voltage while achieving power balance of each cascade unit at all levels. In addition, the switching frequency and loss of each unit are the same, and the working stress of each switch tube is also the same, thereby improving the reliability of the system. The analysis of the fundamental amplitude and power balance of the output voltage of the improved CPS-PWM strategy is analyzed. Moreover, three strategies are listed for comparison, and the strategy is verified by simulation and experiment.
叶满园, 任威, 李宋, 魏麒文, 宋桂智. 基于控制载波自由度的级联H桥逆变器改进型PWM技术[J]. 电工技术学报, 2021, 36(14): 3010-3021.
Ye Manyuan, Ren Wei, Li Song, Wei Qiwen, Song Guizhi. Improved PWM Technology of Cascaded H-Bridge Inverter Based on Control of Carrier Degree of Freedom. Transactions of China Electrotechnical Society, 2021, 36(14): 3010-3021.
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2021, Vol. 36 
