Summary of Machine Design and Current Regulation for the Parallel DPNV Bearingless Motor Winding

This paper provides a summary of investigations into the design of combined windings and precision current regulation techniques for bearingless motors. The parallel dual- purpose, no-voltage (DPNV) winding topology is used to realize both torque and force creation. For significant power applications, it is often advantageous to implement suspen- sion operation independent of the main motor drive. This paper shows that reasonable decoupled operation (force and torque) of combined windings using independent drives is possible through two means: 1) careful design of winding parameters such as number of slots, poles, winding factors, and geometric parameters, 2) careful current regulator design to reject disturbance voltages between the suspension and torque systems. For drives that are not independent (i.e., can transmit data between suspension and torque controllers in real-time), this paper shows that a controls-based direct voltage decoupling approach can be used to ideally decouple force and torque creation. To achieve the highest power density of the bearingless motor, the paper shows that the decoupling approach should be used. Analytical, simulation, and experimental results are presented to verify the results.