Modulation Modes of Promoted Modulators and Their Impacts on Torque of Electrical Machines

This paper introduces the vector magnetic circuit theory into the general airgap field modulation theory (GAFMT). Two new modulators, namely magductance and hysteretance, are proposed, and their vector modulation effects in frequency, amplitude, and phase are clarified. The modulation modes — frequency, amplitude, and phase modulations — are defined. They provide new insight into the modulation effects of various modulators. The effects of modulation modes on torque performance are investigated through specific machine cases, with a particular emphasis on phase modulation. Links among modulation modes, behaviors, and results are established, revealing the similarities and differences among modulators. Guidance on modulator applications is thus developed and demonstrated. The effectiveness of the proposed study is verified through finite element analysis (FEA) and experiments.