Impact of position sensor accuracy on the performance of IPM drives

In this paper, the influence of rotor position sensor accuracy on the performance of an Interior Permanent Magnet (IPM) motor drive for automotive propulsion is presented. Analytical equations describing the torque production in IPM machines show the need for rotor position feedback with high accuracy and resolution, especially for operation in the flux weakening region. Finite element analysis was performed to substantiate this conclusion and also to estimate the torque and power degradation due to the position sensor error. The dynamic angle error of various high resolution/accuracy sensors was measured on the test bench at various operating speeds and temperatures and the measured data was used for computing the impact of angle error on the torque ripple. The details of these results are presented in the paper.