Control scheme for electric drives based on synchronous reluctance machines with a non-linear MTPA controller

This dissertation focus on a Maximum Torque per Ampere (MTPA) control scheme for a non-linear synchronous reluctance motor (Sync-Rel). Due to the absence of permanent magnets, Sync-Rel motors have poor torque production capability and relatively low power factor. Therefore, it is important to maximize the torque given the maximum current of the power inverter. In the classical solution to the MTPA control problem, the d-q current components are considered equal. This solution assumes a linear magnetic circuit for the Sync-Rel motor. In practical applications, the Sync-Rel motor has a non-linear magnetic core. As a consequence, the linear solution to the MTPA problem is not the best one anymore. In this dissertation, we model a non-linear Sync-Rel motor using a simplified magnetic model, taking into account the magnetic saturation. Then, we design a non-linear MTPA controller. The Sync-Rel motor drive is simulated, and the performance of both linear and non-linear controller are compared.