Comparison of Flux Regulation Ability of the Hybrid Excitation Doubly Salient Machines

A hybrid excitation doubly salient machine (DSM) (HEDSM) can adjust the air gap flux with the limited field exciting ampere-turns. There are a few studied structures with different air gap flux regulation abilities. In this paper, several HEDSMs with different structures are analyzed by using an equivalent magnetic circuit method to compare the regulation effects of the wound-field excitation ampere-turns on the air gap flux. Moreover, the consumptions of the permanent magnet are also studied. It is shown that the hybrid excitation structure with different main poles (MPs) has excellent flux regulation ability. Two reasonable combinations of the MPs are presented: The 4PM + 1WF 18/12-pole structure can realize the minimal excitation power, and the 2PM + 1WF 18/12-pole structure, with the unidirectional field current, can simplify the design of the field current controller. A 30/20-pole hybrid excitation prototype machine is used to conduct the no-load and loading experiments, and the results show the good agreement with the analysis based on the equivalent magnetic circuit.