Research On The Key Techniques Of Doubly Salient Hybrid Excitation Generator For Auxiliary Power Unit

Doubly salient hybrid excitation generator has the advantages of simple rotor structure,high reliability,high power density and wide high-efficient operation area,which has attracted more and more attention from scholars and experts at home and abroad.Combined with the application background of auxiliary power unit,this paper will focus on the characteristics of hybrid doubly salient hybrid excitation motor(DSHEM),for the research target of high voltage quality and low vibration.And this paper will conduct a comprehensive and in-depth analysis around the unified mathematical model of doubly salient motor,fast optimization method of DSHEG,suppression of voltage ripple and vibration.Firstly,the basic structure and principle of doubly salient generator with DC voltage are presented and the universal mathematical model is derived,with a description of similarity between switched reluctance generator(SRM)and DSHEG.On this basis,the mathematical model of inductance and a unified principle of I-? loci curves for doubly salient motor are given.And an advanced angle optimization selection strategy is derived.The inductance characteristics identification methods of doubly salient motor are summarized.The flux linkage and inductance characteristics of DSHEG with magnetic bridge under different operating states are discussed by using the frozen-permeability method for flux decoupling analysis.Simulink simulation model of the double salient-pole hybrid excitation generator considering both three phase asymmetry and saturation is built and its steady-state operation characteristics,dynamic characteristics and working characteristics are analyzed.Secondly,a fast optimization method based on improved Taguchi method is proposed.According to the technical requirements for auxiliary power unit and in combination with the steady-state performance and operating characteristics of DSHEG,Taguchi method is conducted to explore the influence of motor parameter factors on the quality factor mean voltage,voltage regulation coefficient and voltage ripple.Parameter factors include number of turns of armature windings and excitation windings,length,stator inner diameter,stator pole arc angle,the width and thickness of the permanent magnets.The interaction effect of the permanent magnet excitation and electric excitations is discussed.An improved Taguchi method with a multi-objective normalized complex function with weighted coefficients is put forward for simplification of final judgement.The method is applied to the design of a "III" typed DSHEG.It has referential significance for further rapid optimization in subsequent chapters.The theoretical analysis and performance of DSHEG is preliminaryly validated by experiments.Thirdly,the voltage harmonic model and inductance asymmetric model of DSHEG are put forward and established.The main cause of DC voltage ripple of "III" Typed DSHEG are analyzed with uncontrolled rectifier.Through the harmonic analysis of DSHEG,a kind of "LTL" type stator optimization model is displayed in the view of the asymmetric three-phase inductance coefficient compensation.A DSHEG is optimized by single-objective Taguchi method for bus voltage ripple suppression.The influence of stator tooth optimization on voltage quality and efficiency was verified by comparison of the experimental results between "III" and "LTL" DSHEG prototypes.The optimization based on inductance asymmetric analysis model is also applicable to other "C" and "E" shaped doubly salient motor.At last,the electromagnetic vibration model of the DSHEG is established and the main causes of electromagnetic vibration are analyzed.The analyses of distribution and harmonic composition of radial magnetic force are given,and the vibration mode and circumferential vibration model of the motor are established.A circular cylindrical shell model based on the correction coefficient is proposed to establish the linear superposition model of circumferential vibration considering the effect of stator tooth on natural frequency.The influence of "LTL" stator parameters on the second resonant frequency is explored.The results show that the second harmonic component of radial magnetic force and the second resonant frequency of stator have a great influence on the circumferential vibration of the motor.The simulation and experiment have proved the effect of "LTL" tooth on restraining the circumferential vibration.The universal mathematical model of the doubly salient machine,the improved Taguchi optimization design method,the "LTL" type stator optimization and vibration analysis model proposed in this paper are the key technical problems of research on DSHEG for APU.The settlements of these problems have great significance for further application and promotion of DSHEG in the auxiliary power unit.