Vibration Reduction Method by Instantaneous Current Control in 120-degree Conduction Mode of Compressor Motor

This paper proposes the vibration suppression method for compressors driven in 120-degree conduction mode. The load torque characteristic of the compressor fluctuates in one period of the mechanical angle. Thus, the speed ripple occurs in the motor, and the compressor vibrates. Therefore, this paper proposes a vibration reduction method with an instantaneous current control with a disturbance observer for the compressor driven by the 120-degree conduction mode. The feature of this paper is that motor speed is estimated by the back electromotive force (EMF) of the open phase due to the 120-degree conduction mode drive. The proposed method is verified experimentally under a limited loaded condition of the compressor as a fundamental study. As a result, the proposed control method reduces the fundamental frequency component of the vibration by 66.4% at a low speed of 0.19 p.u.