Overview and design methodology of doubly salient brushless dc generators with stator-field winding

This study introduces a doubly salient brushless dc (DSBLDC) generator with stator-field winding, which incorporates the doubly salient electromagnetic (DSEM) machine and its associated rectifier. The configuration, operation principle, and armature reaction of different generating mode are overviewed. The sizing equation is derived for the initial dimension design of the DSEM machine. Then the non-linear varying-network magnetic circuit method for preliminary design is proposed to determine the fundamental geometric parameters, the corresponding field magnetomotive force, and winding configurations iteratively, in which the magnetic saturation is taken into account. Furthermore, optimal design of the geometric parameters is comprehensively investigated by finite-element analysis, and the optimised coefficients obtained for different generating mode. The operating characteristics of the DSBLDC generator with compensation capacitors are investigated to improve the voltage regulation performance. A prototype of 12 kW DSEM machine has been designed and optimised by the proposed design methods. Experiments are performed and the results verify the predictions and the design methods. Due to the simple and robust structure without permanent magnet, as well as convenient and flexible control, the promising DSEM machine is a desirable candidate for dc power generation.