Starting assistance device for directly-driven electric vehicle with variable-idle speed control

By introducing a novel permanent magnetic bi-stable electromagnetic clutch unit (PMBECU) in the driveline of directly-driven electric vehicle, a flexible connection between motor and hub is realized with characteristic of separated starting process of drive motor and wheel load. Firstly, the working principle and power supply scheme for the PMBECU is discussed. Then the assembly for the wheel-drive system with starting assistance device by the clutch is investigated. Considering the good dynamic performance of wheel motor, variable-idle speed scheme is presented and the simplified model for fast clutch engagement is built and analyzed. Finally, the proposed method for directly-driven electric vehicle launch is performed on the test rig. The experimental results indicate the shock intensity and electromagnetic impulsion during the starting process is decreased effectively by clutch-coupling startup, which results in good driving comfort and less heat in armature winding of drive motor.