Rotor geometry design of an interior permanent-magnet synchronous machine for more accurate sensorless control

Sensorless control of permanent magnet synchronous machines (PMSM) is often carried out by evaluating current ripples resulting from the supply of high-frequency voltage test pulses. Simulations of a sensorless drive are usually based on a state-space model with constant q and d inductances and no mutual inductances. In this paper, this technique is improved by calculating the inductance matrix from several finite element models (FEM), which allows to study the effect of variable q and d inductances and cross saturation on the performance of the sensorless control. The rotor design is discussed in order to reduce the estimation error caused by cross-saturation.