Sliding Mode Control of A Dry-Type Two-Speed Dual Clutch Transmission for An Electric Vehicle During Optimal Power Transmission Process in Torque Phase

Abstract

In order to properly control slip-to-slip shift process of electric vehicles (EVs) equipped with dry dual-clutch transmissions (DDCT), dynamic modelling of a dry-type two-speed dual-clutch transmission for an electric vehicle in torque phase is proposed at first. Then, an optimal control strategy is proposed to investigate feasibility of non-shock shift process of torque phase without power interruption and power circulation. Optimal solutions of electric motor torque and dual clutch friction torques are derived in analytical form. And then, a dynamic model of fork-lever actuator is integrated into DDCT driveline dynamic model of EV, and an affine nonlinear shift dynamic model for the whole DDCT system is proposed to describe dynamic behaviours in torque phases of shift. Further, to solve problems in tracking inaccuracy induced by strong nonlinearities and modelling uncertainties ofthe dynamic model, sliding mode control strategy based on feedback linearization control theory is proposed. Accurate electric motor torque as well as motor currents imposed to affine nonlinear system are calculated through nonlinear feedback control law. Finally, tracking control accuracy of the affine nonlinear dynamic system is investigated through numerical simulation on MATLAB/Simulink platform. The simulation results verify that not only non-shock shift process of torque phase without power interruption and power circulation is realized, but also torque phase time can be adjusted to an arbitrary value based on actual requirement. Besides, high-precision tracings to optimal angular velocities of electric motor and dual clutch are realized by accurately modulating motor control currents and electric motor torque.