Common-Mode Voltage Suppression Strategy for CHB-Based Motor Drive Based on Topology and Modulation Optimization
Zizhe Wang, Jiaxun Teng, Min Zhang, Zemin Bu, Xinpo Lin, Lei Qi, Wei Zhao, Xin Li, Xiaofeng Sun
Abstract
This article proposes a common-mode voltage (CMV) suppression strategy for the cascaded H-bridge (CHB) based motor drive. CMV can be categorized into two components: the low-frequency component associated with the motor frequency, and the high-frequency component related to the switching frequency. Low-frequency CMV primarily originates from the voltage fluctuations of submodules (SMs), and a topology method of CHB cascading four-port dual-active bridges (CHB-FDAB) is proposed. The CHB-FDAB, in conjunction with synchronous modulation of FDAB three full-bridges cascading with three-phase SMs, can effectively mitigate SM voltage fluctuations and prevent the occurrence of low-frequency CMV, which can also create a reduction for cost and volume of system. High-frequency CMV is generated by the modulation of CHB-stage, and a novel carrier phase-shift pulse-optimization PWM (CPSPO-PWM) strategy is proposed. The CPSPO-PWM can ensure that the difference between the output voltage sums of the left and right arms of the all three-phase SMs is zero, effectively suppressing the generation of high-frequency CMV. Additionally, CPSPO-PWM exhibits minimal increases in current ripple, torque ripple, and system power loss. As a result, the complete suppression of CMV throughout the entire speed range of motor can be achieved. Finally, simulation and experimental results validate the effectiveness of the proposed strategy.