Effects and compensation of magnetic saturation in permanent magnet synchronous motor drives

Abstract
The effects of magnetic saturation are examined, and the compensation of magnetic saturation is proposed for the PM (permanent magnet) motor drives. A speed control system is established based on a DSP, and drive tests were carried out on a prototype IPM (interior permanent magnet) motor. The q-axis inductance of a IPM motor is found to vary depending on the q-axis current because of the magnetic saturation. The terminal voltage exceeds the maximum value in the flux-weakening region and, as a result, the transient responses sometimes become unstable because of saturation of the current regulator. The q-axis inductance is simply modeled as a function of the q-axis current and this compensated value of L/sub q/ is used in the control algorithm. The control performances are greatly improved by the compensation of magnetic saturation.<>