Phase Lead Compensation of a Phase-Locked Loop in an IPMSM for Air-Conditioner Compressors

Abstract

In this study, an interior permanent magnet synchronous motor (IPMSM) for single-rotor air conditioner compressors with small inertia is studied, which adopts a sensorless control based on the phase-locked loop (PLL). Owing to the large periodic motor speed fluctuations, the speed and rotor angle of these compressors calculated by the PLL have inherent lagging phase shift and amplitude attenuation, which deteriorates the field weakening control performance and leads to larger speed fluctuations and current oscillations. In this study, a novel phase lead compensated PLL (PLC-PLL) was proposed to reduce the angle error between the real rotor position and estimated rotor position as well as to improve the performance of field weakening control. This method compensates the phase shift of the calculated angle and then reduces the angle error and speed fluctuations. Furthermore, the method of setting parameters for the PLC-PLL is also given. The experimental results confirm that this scheme can greatly reduce the angle error and the fluctuations of speed and currents, which improves the performance of the controller.