Circulating Current Minimization for Dual Three Phase Motor Integrated Battery Charger

The use of six-phase motors is an attractive option for electric and hybrid electric vehicles due to its modularity. Demand for high power density and lower costs for electric traction drives has led to the idea of integrating the battery charging function into the traction drive. When the main battery for dual motor type electric and hybrid electric vehicles is being charged, the equivalent power converter system is two converters that act as rectifiers and are connected in parallel. Feeding these converters from the AC grid with interleaved discontinuous PWM schemes can result in the appearance of a significant amount of circulating current flowing between the converters. Such circulating current increases converter component stresses and reduces battery-charging efficiency. In the paper, a PWM scheme based on discontinuous PWM methods is proposed to mitigate this circulating current. The proposed scheme does not require additional passive elements and maintains the benefits of discontinuous PWM. Simulation and experimental results are presented to validate the proposed scheme.