Optimal speed control of an Interior Permanent Magnet Synchronous Motor including cross saturation

This paper presents the methodology to design an optimal speed controller (total losses minimization) of an IPMSM for traction applications. IPMSMs have high efficiency, however to exploit that efficiency it is required to design an optimal control, with the capability to accurately calculate and command the current components for the whole range. The speed controller is optimized by calculating the optimal trajectory between two points, defined by their torque and speed. The trajectory calculation is made in two stages: current space vector calculation based on the concept of maximum torque per ampere and optimal trajectory calculation. The first stage corresponds to the calculation of the optimal magnitude and angle of the current space vector for any given torque and speed point, maximum torque per ampere is the control technique selected for the IPMSM model inversion. The second stage involves calculating the currents that define the trajectory from one point to another, with minimal copper losses. The proposed optimization is numerical, constrained, based on the steepest descent method. Simulation and experimental results are presented to validate the proposed methodology.