Simplified Current Control Strategy for Permanent-Magnet Synchronous Motors With Rotor Flux Distortion

In permanent-magnet synchronous motor (PMSM) drives, many current control strategies are presented to compensate the effects of rotor flux distortion on torque performance. These strategies are usually realized in the synchronously rotating reference frame and at least two-phase current sensors are used. Although the technique of phase current reconstruction enables three-phase currents to be obtained with a single dc-link current sensor, two-phase current controllers and complex coordinate transformations are still necessary. In this article, a simplified current control strategy for low-power PMSM drives is proposed. First, a torque allocation law is designed to resolve the reference electromagnetic torque into the reference three-phase currents with compensation for rotor flux distortion. Second, the reference three-phase currents are further converted into the reference dc-link current according to the averaging theory. Third, the amplitude and waveform control of three-phase currents are fulfilled by using dc-link current controller and ac-side pulsewidth modulation, respectively. This strategy can compensate the effects of rotor flux distortion on torque performance and is easy to implement with only one current sensor and one controller. Simulation and experimental results demonstrate the effectiveness of the proposed strategy.