Research on Voltage Control of Dual Motor Hybrid System 2024-01-2219

The paper introduces two methods for controlling motor voltage. One method requires the implementation of boost hardware, while the other allows for voltage control in battery failure mode without any additional hardware requirements. The boost voltage strategy for the hybrid system is based on managing boost modes, determining target voltages, and implementing PI control. The boost mode control includes different modes such as initial mode, normal mode, shutdown mode, and fault mode. Determining the boost target voltage involves regulating the boost converter with variable voltages depending on the operating states of the motor and generator. The second voltage control method without boost hardware is proposed in order to ensure that the vehicle can still function like a traditional car even under abnormal conditions of high-voltage battery failure in micro-mixing systems. In this mode, instead of conventional torque control, the generator operates in a voltage control mode where "voltage" becomes the controlled variable for its controller. The HCU controls the working mode switching of the motor and issues target voltage commands calibrated through actual tests. During system operation, the motor responds to these target voltages in real time. To evaluate the effectiveness of this voltage control strategy, tests were conducted on a sample car with a 2.0T displacement engine. The second voltage control strategy test results indicate that increasing the voltage from 250V to 450V significantly enhances power output at 6500rpm, resulting in a remarkable boost of approximately 117% (from 71 kW to 155 kW). This improvement leads to enhanced acceleration performance at high speeds and improved vehicle dynamics. The outcomes of the second voltage control strategy demonstrate that smoothly transitioning into voltage control mode and ensuring seamless operation when disconnecting the high voltage battery relay is achievable. This operational mode guarantees uninterrupted vehicle functionality even in cases of abnormality with the high-voltage battery. Additionally, serving as an auxiliary driving mode, it further strengthens the safety and robustness of the overall system.