Study On Electromagnetic Principle And Characteristics Of Coarse And Precise Coupling Axial Reluctance Resolver

Axial reluctance resolver is a kind of precise control micro motor in automatic device.In control system of motor,it is mainly used for data transmission of rotor angle.The axial reluctance resolver has the advantages of high precision,small volume,small moment of inertia,anti-interference,high temperature resistance and high humidity resistance,so it can be widely used in the fields of national defence,spaceflight,automobile,etc.signal,which can not complete high-precision measurement.Multiple pole pairs single channel axial reluctance resolver can carry out high-precision measurement,which can not achieve signal output of absolute position.In order to ensure absolute measurement of rotor position information under high precision,this paper takes a kind of coarse and precise coupling axial reluctance resolver(CPCARR)as the study object.The problems of electromagnetic principle analysis of CPCARR,inductances calculation,analysis and calculation of electromagnetic field,analysis and optimization of signal windings EMF of precise machine,influence of eccentricity and offset of stator and rotor on measurement precision are studied.This paper mainly includes the following parts:a new structure of CPCARR is put forward.Winding types of excitation winding and signal windings,type of stator core,magnetic wavestrip structure of rotor are determined.In ideal state,the coupling area between stator and rotor is derived by analytical method.The variation law of air gap permeance of CPCARR is obtaned when angle of rotor changes.Through above studies,voltage equation and equivalent circuit are established.The results show that output EMF of signal windings of coarse machine are in accordance with characteristics of 1 time sine function and 1 time cosine function,and output EMF of signal windings of precise machine are in accordance with characteristics of P times sine function and P times cosine function,which proves the feasibility of design concept of CPCARR.According to the structure complexity and the calculation difficulty of inductance parameters of CPCARR,the winding function method is used to derive inductances of CPCARR under equal turns winding type and sine winding type.Variation laws of self inductances and mutual inductances of two different winding types are comparatively analyzed.The relationship between inductances of windings and errors of CPCARR is got,which provides theoretical basis for improving the measurement precision of CPCARR.Corresponding experiments prove analysis results of inductances and simulation results of inductances are basically consistent with measurement results of inductances,which illustrates the feasibility and validity of inductance calculation method of CPCARR.By using finite element method to analyze the electromagnetic field of CPCARR,the influence of various structural parameters on magnetic field distribution of CPCARR is revealed,which provides guidance for improvement of electromagnetic property of CPCARR.According to establishing voltage equation of CPCARR under the condition of slot effect and uneven distribution of magnetic field,output characteristics of CPCARR and THD influence factors of output EMF of precise machine are obtained.The suppression effect of different structural parameters on THD of output EMF of precise machine is analyzed.The results show that structural improvement of CPCARR can make the magnetic field distribution more uniform.THD of output EMF of precise machine can be effectively suppressed by correcting parameters,such as length of air gap,number of stator teeth,ratio of precision and coarseness of rotor,relative phase angle of rotor.The method of superimposing harmonics in shape function of rotor can also suppress THD of output EMF of precise machine.Under equal turns winding type and sine winding type,assembly problems of stator radial eccentricity,rotor radial eccentricity and rotor axial offset of CPCARR are studied by finite element method.And the influence of above problems on measurement errors of CPCARR is analyzed.Experiments of a prototype of 15 pole pairs CPCARR are carried out,which verify the effects of three kinds of assembly problems on measurement errors.The variation law of output EMF under different eccentricities is obtained,which provides a reference for the compensation of angle measuring circuit in the following work.The experiment results show that,in the case of ensuring rotor axial offset within 50% of stator tooth height,rotor axial offset does not make output EMF of signal windings of precise machine generate additional error.However,rotor axial offset can reduce the output EMF amplitude of signal windings of precise machine.Radial eccentricity of stator and rotor could result in additional function error of output EMF of precise machine signal windings.In the same time,radial eccentricity of stator also causes additional zero position error.