Nonlinear torque control of the induction motor in hybrid electric vehicle applications

In this paper, the torque tracking problem of the induction motor for hybrid electric vehicle (HEV) applications is addressed. Because the standard field oriented control (FOC) provides poor performance under rotor resistance uncertainty, a new robust controller-observer combination is designed in this paper in order to improve the overall performance. Our controller is based on a new PI-based extension of the FOC controller while our flux observer is based on the sliding mode technique. Simulation results show robustness with respect to rotor resistance uncertainty. A new optimal flux reference is derived to minimize the consumption of electrical energy, rather than the commonly used standard flux reference that maximizes motor torque. This choice is justified by the use of our controller in HEV applications. Simulation results show a significant reduction (35%) in energy losses.