Efficiency analysis of planetary coupling drive system with dual motors on electric bus

This paper focuses on system efficiency analysis of the planetary coupling drive system with dual motors on an electric bus. This work is motivated by high efficiency and compact structure of the planetary coupling drive system, which has been recognized as one of the most popular drivetrain in hybrid electric vehicles (HEVs). This paper seeks to improve the system efficiency, while satisfying the driving power demand. First, the structure and working principle of the planetary coupling drive system with dual motors are proposed, including single-motor mode and dual-motor mode. Second, we use the motor efficiency map to determine work area of different working modes, mode switching curve, and the motor control speed in dual-motor mode. Finally, based on standard city suburban cycle, we examine the performance of planetary coupling drive system with dual motors through control strategy considering the efficiency. The result demonstrates that the electric bus with dual motors can effectively improve system efficiency through optimal control strategy.