Performance Comparison of AFDS PMSG During Voltage Regulation by Mechanical Field-weakening in Extended-speed-range

Abstract

Background: Axial-flux permanent magnet synchronous generators (AFDS PMSG) have been found suitable in wind energy conversion system and electric vehicle owing to its compactness, high torque capability at low speed, high torque to inertia ratio, modular geometry, and high magnet usability index. Such applications require the generator to operate in Extended Speed Range (ESR). In ESR, voltage regulation is achieved by generator field-weakening. Usually, negative daxis current is injected in the armature winding of the generator to achieve field-weakening. However, in the axial-flux machine field-weakening by current injection is not substantial due to the low inductance of the machine and use of permanent magnets with high coercivity. We have revised all patents related to field-weakening methods applied to axial-flux permanent magnet generators. Methods: Therefore, this paper emphasizes field-weakening using mechanical methods. This paper compares the performance of AFDS PMSG topologies based on its mechanical-field-weakeningbased voltage regulation capability. In this paper, generator field-weakening is achieved by angularly displacing, one of the stators with respect to the other via a mechanical actuator. Results: The experimental results show that during voltage regulation of the DS PMSG with perfectsinusoidal back-emf characteristic, least amount of harmonics is injected in the generated output power. Conclusion: Thus, the same is best suited to design an automotive generator based on MFW method for wind energy conversion system and electric vehicle running in ESR.