Abstract: In order to validate the shift strategy of 2-speed automatic mechanical transmissions (2AMT) for electric vehicles, the powertrain test rig including high performance electric dynamometer is built up and experiments under different conditions are made. Then, a compound optimal control strategy is presented to improve the shift performance. In other words, a linear quadratic regulator is employed to actively compensate the drive motor torque and a nonlinear time-optimal control is used to track the actuator rotor position. The experiment results show that this optimal control strategy can not only reduce the driveline vibration, but also cut down period of the shift time. The coupled dynamic model of the driveline and shift actuator is precise enough for the analysis of shift process, and the compound optimal control strategy is effective to improve the shift quality.

Key words: 2-speed automatic mechanical transmissions (2AMT), combined control, shift shock, optimal control