| Starter generator technology is the core technology of more electric/all electric aircrafts.The aerospace,military vehicles and other industries raise higher requirement for the reliability of starter generator system,and even requested that the machine have the fault-tolerant ability to operate with equal or derating capability in case of failure.One important technique to improve the reliability and achieve the fault-tolerant function of the starter-generator is to design multi-phase machines.Since the doubly salient electromagnetic machine(DSEM)have a good characteristic of voltage regulating and is suitable to be a starter generator,it is very necessary to carry out the study of fault-tolerant technology with this type of multi-phase starter-generator.This thesis contains the follows:To improve motor fault tolerance and prevent the spread of the fault,the redundancy structure with multi-phase and fault isolation technique should be adopted with the analysis of the DSEM failure.Based on the design requirements for DSEM,the relationship between performance parameters and topology parameters that includes stator pole,rotor pole and their pole arc coefficient was analyzed.The constraint rules of the machine stator pole,rotor pole and their pole arc coefficient for multiphase doubly salient machine was given.In the conventional multi-phase DSEM,the phase with short magnetic circuit has large phase inductance,and the phase with long magnetic circuit has little phase inductance.In order to solve this phase asymmetry problem,a new DSEM with short pitch field windings was proposed by winding three armature coils of one phase in different locations.A new five-phase Doubly Salient Electromagnetic Generator(DSEG)with the field winding curling around three stator poles was proposed in this paper.To calculate the airgap magnetic flux density,the analytical model of the air length in the magnetic path in different positions was deduced,which includes airgap,stator slot air length and rotor slot air length.The analytical model has a high accuracy to analyze the static magnetic characteristics of DSEG.A novel six-phase DSEM with little commutation torque ripple and complementary dual channel was proposed.It was pointed out that only the six-phase DSEM with field winding wound across one pole has symmetrical phases.And the analytical model of the pole overlap angle was deduced to express the inductance models for the six-phase DSEM.As a typical example,the analytical models of the inter-turn short-circuit current both in generator state and motor state were proposed,which showed that the short-circuit current should be diagnosed and isolated quickly.A four-phase DSEM fault-tolerant power converter with five arms was proposed.It can take the advantage of working in half cycle of the DSEM,and achieve fault tolerance with single-tube open and single-phase open circuit.Two IPMs were used to build a six-phase dual-channel fault-tolerant converter to realize the fault tolerance with single-tube,single-phase and single-channel open circuit.The rectifier topologies of the multi-phase fault-tolerant DSEG were presented.Take the four-phase DSEM as an example,the fault-tolerant characteristics were analyzed when it was normal,have a fault of single-tube or single-phase open circuit.The Matthew effect on current of the DSEG was pointed out,which makes the larger phase current larger and larger.The prototype machines with 24/18-pole four-phase and 12/10-pole six-phase DSEG have been developed with the above characteristic.And an experimental platform was set up to carry out the verify experiments for the multi-phase Doubly Salient Electromagnetic Starter Generator(DSES/G)and its bi-directional converter. |
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