Approximative real-time suitable solution of the direct-axis current setpoint problem for magnetically anisotropic permanent magnet synchronous machines during field weakening

Abstract:
In this article, a method is presented with which a suitable direct-axis current setpoint can be determined in real time for magnetically anisotropic permanent magnet synchronous machines in the field weakening range. The aim here is to provide a predetermined torque setpoint utilizing the available maximum voltage with the lowest possible stator current setpoint space vector magnitude. The focus here is on finding a suitable approximation for the relevant zero of a fourthdegree polynomial with low effort and in real time. Measurement results confirm the efficiency of the method presented.