Influence of Bus Voltage on Motor Torque and Efficiency in Fuel Cell Hybrid Powertrain

Abstract

In order to evaluate the influence of bus voltage on motor torque and efficiency, bench experiments were designed on a dynamic dynamometer. The torque and efficiency of three-phase asynchronous induction motor were measured with the bus voltage changing between 400 V and 455 V. The result shows that (1) the motor efficiency is mainly affected by the bus voltage in low-efficiency area, actual motor torque has an average delay time of 0.5 sec compared to the target torque command; (2) actual torque is lower than target torque in high-bus voltage and high-motor speed range because of self-protection of the motor controller. Results in “Chinese typical city bus cycle” testing shows that the working points are mainly distributed in the high efficiency area which is affected by bus voltage slightly. As a result, the influence of bus voltage on motor efficiency could be ignored in city bus cycle analysis.