Optimal System Efficiency and Fault-Tolerant Control of AFPM Machines Drive for Electric Bus Propulsion

The battery electric bus needs the electric motor to run efficiently over the entire speed range. And it also expects the motor has the ability of fault-tolerant operation. This paper aims at the demands for high efficiency and the fault-tolerant operation of propulsion system. With the good performance of axial-flux permanent magnet (AFPM) machine, the multi-disc AFPM machines are selected. According to different torque demand, road condition and the motor efficiency map, the electric vehicle (EV) controller promptly adjusts the number of working AFPM machines and the output torque of modular AFPM machine to improve the overall energy-efficiency. Based on the modular motor operation condition, the fault-tolerant strategy is adopted to remove the faulted motor in time to enhance the propulsion system reliability.