Regulation of Electric Vehicle Speed Oscillations Due to Uneven Drive Surfaces Using ISMDTC

Abstract

An unbalance in the electromagnetic torque and the load torque occurs when Electric Vehicles (EVs) are driven through uneven terrains. This leads to non-periodic and time-varying speed oscillations. As a result, torsional vibrations increase and leads to passenger discomfort and mechanical stress on the EV body. The EV drive control should be designed to mitigate these speed oscillations. In this paper, an Integral Sliding Mode Control Based Direct Torque Control (ISM-DTC) of Induction Motor (IM) is proposed to inherit the intrinsic properties of disturbance rejection, robustness against parametric variations, operational uncertainties, and improve the conventional Proportional-Integral (PI)-based DTC (PIDTC) performance in uncertain EV drive conditions. The proposed control is integrated with PIDTC, which maintains the speed and acts as a nominal control. The non-linear ISM loop cancels out the speed fluctuations by balancing the electromagnetic torque with dynamic load torque demand. The proposed control cancels out the matched uncertainties without amplifying the unmatched uncertainties in system dynamics. An analysis of the uncertainty decomposition and control gain derivation is presented. The proposed ISMDTC is verified through simulations and experiments considering different scenarios of torque, reference speed variations, uncertainties, and the standard New European Driving Cycle (NEDC) and Urban Dynamometer Driving Schedule (US) drive test cycles.