Modeling, simulation and control of a seamless two-speed automated transmission for electric vehicles

Power transfer and gear shifting control are the main duties of the transmission in a vehicle. This paper focuses on the modeling, simulation and control of a two speed automated transmission for electric vehicles having a seamless gear shifting specification. The transmission incorporates two-stage planetary gear sets and two braking mechanisms to control the gear shifting. Controlling the input power of the electric motor and the embedded brakes provides seamless flow of power during a gear change. The dynamic model of the mechanism has been developed by using the power and the kinematic equations of the planetary gear trains and the free body diagram of the mechanism. The simulation model has been built up in MATLAB/Simulink^® to investigate the performance of the proposed controller. The control algorithm is inspired by the two main control phases in Dual Clutch Transmissions (DCT), namely the torque phase and the inertia phase. An Input Output Feedback Linearization control technique with a PID controller are used for the torque phase and an optimal MIMO H_∞ controller is designed for the inertia phase. Simulation results show the ability of the proposed transmission with the control algorithm to have a smooth gear change without excessive oscillations in the output torque and speed.