Analysis of a Novel Hybrid Excitation Synchronous Generator With AC Field Winding

In this paper, a novel hybrid excitation synchronous generator with AC field winding (AC-HESG) is proposed to improve the flux-regulation range and maintain constant output voltage. The distinguishing feature of the proposed generator is a hollow magnetic barrier on the rotor and two sets of windings on the stator. The armature winding generates sinusoidal voltage, and the field winding is connected to an excitation converter, which can adjust both the amplitude and phase of the field current. Theoretical analysis of flux-regulation principle is conducted by studying the relationship between field magnetomotive force, rotor reluctance, and air gap flux density. Quantitative analysis is performed using a simplified equivalent magnetic circuit method (MEC). Subsequently, magnetic field, no-load and load characteristics are investigated through finite element analysis. The impacts of speed, field current amplitude and phase, and load on output voltage and field-regulation efficiency are analyzed. Finally, a 1.5 kVA, 1500 r/min prototype is developed and tested. The test results show good flux-regulation capability and stable voltage output performance of the proposed generator.