An LQR based optimal tuning method for IMP-based VSI controller for electric vehicle traction drives

The electric motor drive system is one of the most important portions of an Electric Vehicle (EV) where the electric motor is supplied by a Voltage Source Inverter (VSI) as an option which is frequently used in single- and three-phase powertrain configurations. This paper illustrates a new method for VSI linear controller coefficient tuning that ensures tracking of the output voltage versus applied reference voltage command in two controller strategies (Proportional-Integral (PI) and Proportional-Resonant (PR)) corresponding to single- and three-phase VSI system case studies. Those controllers are placed within a general structure offered by the Internal Model Principle (IMP) of control theory. The proposed method in this paper is based on redefining the LQR problem in order to improve its capability of addressing the optimal tracking problem. Two specific examples of the method are provided, one for a single-phase VSI and the other for a three-phase VSI. The method as applied to the tuning of a PR and a PI controller, respectively, are studied in detail. Simulation and CHIL (controller hardware in the loop) results are provided for validation of the analytical derivations.