Research on the Oscillation Reduction Control During High Voltage Battery Failure in Hybrid Electric Vehicles

In order to achieve seamless mode switching control for hybrid electric vehicles (HEVs) in the event of battery failure, we propose a motor voltage-controlled mode switching method that eliminates power interruptions. This approach is based on an analysis of the dual-motor hybrid configuration's mode switching. We analyze the overall vehicle operation when the high-voltage battery occurs in different hybrid modes. To ensure that the vehicle can still function like a conventional car under such circumstances, we introduce a novel "voltage control" mode. In this mode, instead of operating in its traditional torque control manner, the P1 motor adopts a voltage control strategy. The P1 controller's variable becomes "voltage," and VCU sends the motor's working mode switching request and PCM finishes the mode transition. During system operation, the P1 motor promptly responds to these target voltages to maintain bus voltage within a normal range. The P1 motor voltage is monitored and managed by PCM to ensure safe operation under load conditions and the driver torque request is satisfied by the engine. Tests were conducted on both a motor bench and a sample car to investigate how motor speed and 12V load affect voltage control mode performance. Results demonstrate that smooth mode transition and smooth entry into voltage control mode allow for uninterrupted operation of the motor without any issues or disruptions when disconnecting the high-voltage battery relay during abnormal situations with high-voltage batteries present. This operational approach ensures continued vehicle functionality even during abnormal high-voltage battery situations while enhancing system safety and robustness.