Sensorless Induction Motor Drive Using Indirect Vector Controller and Sliding-Mode Observer for Electric Vehicles

This paper presents a sensorless control system for an electric-vehicle (EV) induction-motor (IM) drive embedded with an indirect vector controller and a fixed-boundary-layer sliding-mode (FBLSM) observer. No speed or even voltage measurements are required. This novel FBLSM observer could accurately estimate the speed and flux even without known load torque, where chattering on estimations due to switching functions in normal sliding-mode observers is almost completely eliminated. The proof of observability in a wide speed range (including very low speeds) is given. The indirect vector controller with feedforward compensation is responsible for tracking motor speed or torque commands, which manages to accelerate algorithm processing and to enhance transient performance. The experimental results based on a high-power driver-load motor configuration validate the accuracy of the observer and the dynamical performance of the controller under multitrapezoidal speed and vehicle driving cycle torque-speed commands, taking into consideration unexpected parameter disturbances.