Automatic d-Axis Estimation of Magnetic-Geared Motor Utilizing Position Sensorless Control

Abstract

　This paper describes an automatic d-axis estimation of a magnetic-geared motor using position sensorless control. The magnetic flux due to the permanent magnet appears in the q axis as well as in the d axis in a magnetic-geared motor when a load is applied to the low-speed rotor. Therefore, 2 position sensors are needed to detect the direction of the total permanent magnet flux. In this paper, an automatic d-axis estimation method for a magnetic-geared motor using sensorless control is proposed. The electric circuit equation of a magnetic-geared motor is shown, and mathematical sensorless control model based on an extended electromotive force model is described. Finally, the effectiveness of the proposed d- axis estimation method is investigated by the comparison of the mathematical simulation, finite element analysis, and measurements on a prototype.