Characteristic Research Of Novel Six-Phase Axial Flux Permanent Magnet Synchronous Machines

Since the axial flux permanent magnet synchronous machines(AF-PMSM) have advantages of high efficiency, high power density and compact structure, the AF-PMSM have gained more and more attention in research and practical application. For the applications such as wind generation, marine propulsion and more electric aircraft, the PM machines are required to have strong fault-tolerance ability. So it is important to study the AF-PMSM with strong fault-tolerance ability for improving the performance of PM machines used in military and civilian areas. This paper studies the novel 6-phase AF-PMSM from the following aspects:Firstly, the fault-tolerance characteristics of 6-phase PMSM are analyzed. When one phase is open circuit, the neutral point connection of 6-phase PMSM and the common fault-tolerant control method are summarized. Under the minimum current fault-tolerant control and minimum copper loss fault-tolerant control, the effects of different neutral point connection on electromagnetic loss, torque and voltage of 6-phase PMSM are separately analyzed. The effects of minimum current fault tolerance control and minimum copper loss on the performance of 6-phase PMSM are also compared.Then, a novel 6-phase detached winding is proposed to improve the fault-tolerance ability of machine. The design method of 6-phase detached winding is firstly given, and the available slot-pole combination and the corresponding winding factor for 6-phase detached winding are also given for reference. The winding factor difference between 6-phase conventional winding and 6-phase detached winding is explained.Then, the effect of 6-phase conventional winding and 6-phase detached winding on the performance of AF-PMSM is compared. Performance in aspect of the EMF, rotor eddy current loss, iron loss, torque and inductance under normal operation is compared. Comparison of performance including rotor eddy current loss, torque and rotor unbalanced axial force under fault-tolerance operation is also mentioned. The different effects of two 6-phase windings on the performance of the motor are explained in the theory.An AF-PMSM prototype with 6-phase detached winding is design. The no-load test is performed to verify the proposed winding structure.