Dual-Gap Dual-Pole Composite Machine for Mechanical Rotor Position Estimation

Position sensorless control has been widely studied for electrical rotor position estimation. However, because of the magnetic periodicity, mechanical rotor position sensorless control of multipole electric machine was hardly reported. By increasing the control dimensions, this article proposes novel machine topologies named as dual-gap dual-pole composite machines, where the mechanical rotor position can be demodulated from the electrical rotor positions of two air gaps. The machine topologies and corresponding control theory are elaborated, and one of the topologies is selected as the primary prototype, which is composed of a permanent magnet synchronous machine with six poles and a variable reluctance resolver with four poles. Detailed design and analysis on the prototype along with the control strategy are presented. Finally, experiments are carried out based on the prototype to verify the feasibility of the proposed methodology.