EXCITATION AND CONTROL ANALYSIS OF LEVITATION FORCE WINDING FOR MAGNETIC SUSPENSION BEARINGLESS MOTORS
WANG Bao-guo, WANG Feng-xiang (School of Electrical Engineering, Shenyang University of Technology, Shenyang 110023, China)
In this paper excitation modes and control stra-tegies of levitation force winding for magnetic suspension bearingless motors are analyzed. From the operation principle of a beaingless motor, the relation between pole-number selec-tion of windings and two equivalent motors operation modes can be obtained by using the equivalence of the motor to two equivalent motors with different pole numbers and studying the relative motion between magnetic field and the rotor. The relation between pole-number selection of windings and excita-tion modes of levitation force winding can be further derived. From the relations, it is concluded that pole-number selection of windings not only determines direction of electrical energy transfer for levitation force winding, but also does its excitation modes. For two kinds of excitation modes and control methods existing in levitation force winding, the paper mainly discusses how to control current in levitation force winding operating under self-excitation mode. A novel method of a capacitor in parallel with inverter is presented, in which current in levitation force winding can be controlled by PWM technique. Finally, experimental results are shown in the paper.