The Structure, Principle And Characteristics Of New Type Doubly Salient DC Generators

The Doubly Salient Machine (DSM) is a new type Variable Reluctance Machine (VRM) based on the Switch Reluctance Machine (SRM) with salient in double sides of the gap between rotation part and state part. The Doubly Salient DC Generator (DSDCG) is a Brushless DC generator (BLDCG), which is composed by a DSM and the static rectifier connected with the machine's armature windings. There is no permanent magnet or exciting windings in the rotor that is fabricated by lapped ferrosilicon sheet. Both the exciting device (permanent magnet, exciting windings) and armature windings are embedded on the stator slots. This machine's structure guarantees the sum of the overlapping angle of stators and rotors at any time is constant. Such that the DSDCG can boasts of its advantages: simple construction, high reliability, high speed, high power density, no orienting torque when static exciting, no excited e.m.f. in the exciting windings, etc. This paper adopts a methodology combined by simulation and lab verification. Simulation for DSDCGs in this paper is all based on the Transient FEM.This paper first makes a precise and essential review on the development of research and application of DSM in the recent score years; then from analysis of machine topologies on, systematically establish the theory on the DSM structure and principle. This paper, which discusses the single phase, two/four phase DSM, three phase DSM, five phase with fault tolerance capability, and poly-phase such as six or seven phase DSM, including both wound field, permanent magnet excited DSM and the differences about the design thumb, emphasizes the physical nature and relation between the machine structure and static parameters. This paper also introduces the detail of the hybrid type's typical structure and operation mode; makes a concise definition of four generation modes; and the concepts of the Doubly Salient Motor and Starter/Generator.This paper then analyzes the operation characteristics in detail of the 12/8-2 three phase wound field DSDCG in the aero-starter/generator system, including nonload characteristics, short-circuit characteristics, external characteristics and regulation characteristics with three different generation modes; typically, studies the influence of exciting current, speed, armature winding turns per phase, machine core length, gap length and load types to the external characteristics with switch reluctance generation mode. Commutation overlapping and armature reaction, which are coupled with each other mechanismly, is the significant phenomena of DSDCG under real loads. At last this paper comparatively studies the numerical relationship between increasing machine cells and increasing output power, based on the concept of the cell machines composing one DSM; and when the gap, exciting A.t. per machine cell, speed and armature diameter is kept constant, the functional relationship between the number of stator and rotor poles and the DSDCG's output power; then a conclusion is made that a maximum number exists, such that it provides a beneficial reference for boosting DSDCG's output power.