Study on inverter-fed three-pole active magnetic bearing

The most popular active magnetic bearing (AMB) system has four magnetic pole-pairs. In general, the sensors and the power amplifiers account for the major portion of the cost, and fewer power amplifiers are used for the AMB with fewer magnetic poles. Therefore some researchers proposed the three-pole AMB, and presented two control configurations. Herein the inverter-fed three-pole AMB was further studied. A linear analytical model considering the air gap eccentricity was presented. In this model, the force in the x and y direction are uncoupled and they could be divided into the controlled levitation force, the unilateral magnetic force and the bias force. Its accuracy was verified by the simulation results of Maxwell 2D based on finite element method. Owing to the decoupled analytical model, the traditional PID control method could be used in the three-pole AMB. The inverter-fed three-pole AMB control system with displacement control in the outer loop and hysteresis current control in the inner loop was proposed. Based on the simulator coupling technology, the simulation results of software SIMPLORER verify the performance of the control method.