Efficiency analysis by numerical calculation of moments and losses in a interior permanent magnets synchronous motor

Abstract

The paper presents a dynamic model of a synchronous motor with permanent magnets located inside the rotor (SMIPM) and with a concentrated type of stator winding. In order to improve drive efficiency, the accuracy of the model was increased by including losses and nonlinear parameters of the magnetic circuit in the motor model. The main advantage of SMIPM, compared to asynchronous and commutator motors, is achieved by providing a higher magnetic flux density in the air gap with less losses, which is reflected in higher mechanical energy delivered per unit volume of the motor, or increased motor efficiency. The paper performs numerical calculations of moments and losses in the motor by the finite element method for wide current. Accurate calculation of losses in the iron core is a very complex procedure, which is why many authors usually give the mean value of magnetic induction for the entire volume of the core. The great advantage of this calculation is that it gives a real 3D image of the machine losses for all operating conditions, at different frequencies and currents in the d and q axes. Finally, an example of measured and numerically calculated torque is given to confirm the correctness of the efficiency determination method.