Reduction of Estimated Rotor Position Error of PM Synchronous Motor by Real Time Inductance Estimation

In sensorless control systems based on the extended back emf of a permanent magnet synchronous motor, errors between the motor parameters in the estimator and the real system lead to inaccuracies in the estimated rotor speed and position. One of the primary causes of errors in the estimated rotor position is the variation in inductance resulting from magnetic core saturation as the current increases. This study proposes a real-time inductance estimation algorithm to minimize errors in the estimated rotor position. The dq inductances are derived from the current variations in response to injected high-frequency voltages. Simulation and experimental results show that the inductances are accurately estimated, which leads to a reduction in errors in the estimated rotor position.