A Split-Field-Windings Doubly Salient Brushless DC Generator With Reduced Excitation Capacity for Hybrid Electric Vehicles

Abstract

This paper proposes a split-field-windings doubly salient brushless dc generator (SDSBLDCG) to reduce excitation capacity. The series field winding connected at the dc side of the associated rectifier provides part of the field magnetomotive force. A split factor is introduced to indicate different combinations of the field windings based on the same slot fill and current density. Then, the influence of split factor on the generator performance is investigated by finite-element analysis. The dynamic characteristics of the SDSBLDCG system are also analyzed to evaluate the adoptable split factor. A 43 kW prototype SDSBLDCG with 24 stator poles and 16 rotor poles having optimized split factor, as well as its generator control unit, is designed and developed for the medium-duty hybrid electric bus. The capacity of the field current regulator is reduced by 45% compared with that of the conventional doubly salient brushless dc generator. The utility of the controller and the dynamic performance of the system are also verified. Both simulated and measured data show that the proposed SDSBLDCG is a promising candidate for the on-board generator system, particularly in medium- and heavy-duty hybrid electric vehicles.