Semi-Zero Power Control of a Permanent Magnetic Suspension System with Constant Air Gap Length

This paper proposes a semi-zero power control method of a permanent magnetic suspension system using a flux path control mechanism with a constant air gap. This permanent magnetic suspension system consists of a disk-type permanent magnet, two “F� type iron cores, a rotary actuator with an encoder and a reducer, and a suspended object with a bar shape. In this system, the gravitational force of the suspended object is transmitted to the base part of the system, and the actuator only drives the permanent magnet rotate. Therefore, this system can realize the semi-zero power control. Moreover, when the mass of suspended object increases, the system just changes the bias angle of the permanent magnet, and maintains the air gap length constant. In another way, this system also can maintain the bias angle of magnet constant, and changes the air gap length short to realize the semi-zero power control. This paper focuses on the semi-zero power suspension characteristics of this system, elaborates the system’s mechanism, and analyzes the semi-zero power suspension performances with a constant air gap length.