Axial Modular Variable Flux Reluctance Starter Generator With Step-Staggered Rotor to Eliminate Phase-to-Phase Coupling

In this article, an axial modular variable flux reluctance starter generator (AMVFRSG) with dc field excitation is proposed, which can achieve physical isolation between field windings and armature windings comparing with conventional structure. The axial modular design theory is demonstrated via three-dimensional finite-element method, and the AMVFRSG is optimized to simultaneously achieve both starting and generating performance. Fault-tolerant capabilities including elimination of coupling, suppression of short-circuit current, and fault-tolerant operation are investigated and compared with conventional structures. Additionally, the influence of rotor poles on AMVFRSG performance is analyzed. Finally, a prototype is manufactured and tested, including no-load, starting performance, generating performance, fault and fault-tolerant operation tests to validate both the theoretical and finite-element analyses.