Speed sensorless electric vehicle propulsion system using hybrid FOC-DTC induction motor drive

This paper describes a control scheme of speed sensorless hybrid field oriented and direct torque control of induction motor for electric vehicle (EV). EV requires fast torque response and high efficiency of the drive. The operating flux of the motor is chosen optimally for losses minimization and good dynamic response. The drive performance is studied for acceleration, braking and flux-weakening (above the rated speed). A control scheme for robust flux-weakening operation of motor drive is adopted. The basic idea is to adjust the flux reference on the basis of the q-axis stator current error, thus determining a spontaneous flux weakening. Furthermore, a loss-model-based controller (LMC) is applied to optimize the induction motor drive. Simulation results show that the proposed DTC is able to follow the reference speed with a reasonable dynamic and relatively low error.