Sensorless interior permanent magnet synchronous motor drive system for air conditioners

This paper proposes a new rotor position estimating method by detecting the stator currents under each PWM switching state for an interior permanent magnet synchronous motor drive system. The proposed sensorless drive system can be applied in an air conditioner without injecting any high-frequency sinusoidal or cosine voltage signal. The operating speed range can be effectively extended because the maximum available voltage is increased when compared to the high-frequency sinusoidal or cosine voltage injection method. A digital signal processor, TMS-320-F-2812, is used to execute the rotor position estimator and controller. Several experimental results are included to evaluate the theoretical analysis. The experimental results show that the proposed sensorless method can provide satisfactory performance for a closed-loop interior permanent magnet synchronous motor drive system applied in an air conditioner.