Experimental validation of 3D magnet eddy current loss prediction in surface mounted permanent magnet machines

This paper presents the experimental validation of 3D Fourier method employed for predicting magnet eddy current loss in surface mounted permanent magnet (SPM) machines. The magnet loss is measured for a 12-slot,14-pole SPM machine from experimental tests when the machine is operated with inverter under locked rotor conditions by repeating tests with two rotors, one with magnets and one without. The eddy current loss associated with each significant harmonic in the captured armature currents is predicted separately employing the developed method and the total magnet loss is evaluated by applying the principle of superposition. The magnet loss at real operating conditions of the machine is predicted from the method using the phase current captured when the SPM is operating at its maximum speed conditions. The result is used as example to devise an effective means of further reduction in the total magnet loss.