The accuracy of the classical machine phasor diagram and on-line measurements for permanent magnet machines

In this paper test results are presented which explore the accuracy of the classical phasor diagram and on-line measurements for permanent magnet machines. The Jones-Bridge inductance measurement test is described and used to provide synchronous inductance measurements. These are combined with measurements made with a commercial power analyzer and with online parameter estimations, allowing for reconstruction of the phasor diagram. The predicted load angles and terminal voltages are compared to the measured and estimated values, allowing for an evaluation of both the phasor diagram predictions and the estimation techniques. While validating the estimation techniques presented, the results show that the classical phasor diagram does not accurately predict the performance of the permanent magnet machine even at relatively low speed and low current operation. Reasons for this are presented along with suggestions for future work to address this inaccuracy.