Analysis and Verification of the Doubly Salient Brushless DC Generator for Automobile Auxiliary Power Unit Application

The doubly salient brushless dc generator (DS-BLDCG) is constituted by a doubly salient electromagnetic generator (DSEG) and the associated rectifier circuit. The DS-BLDCG is suitable for the automobile auxiliary power unit (APU) application due to its merits of simplicity, high robustness, low cost, and flexible control. Since no constraint is imposed to the number of phases of the onboard brushless dc generator, the polyphase DSEG can be employed. In this paper, a 3-phase 12/8-pole DSEG and a 4-phase 16/12-pole DSEG with a rectifier circuit for the APU application are proposed. The taper stator pole and broadened rotor pole structure utilized to increase maximum output power is introduced in the four-phase DSEG design. Based on the two-dimensional (2-D) finite-element method (FEM) and field-circuit coupling analysis, a comprehensive comparison is presented. The 16/12-pole DS-BLDCG with broadened rotor pole exhibits lower peak value of the phase inductance yet larger negative phase current commutation overlapping angle. The rectifier circuit of the 16/12-pole DS-BLDCG is more complex and the copper consumption of the 12/8-pole DS-BLDCG is slightly less. A prototype 12/8-pole DS-BLDCG for the APU application is designed and developed. Both the simulation and experimental results indicate that the developed DS-BLDCG is a promising option for automobile APU application.