The Equivalent Magnetic Circuit Of Dual Consequent Hybrid Excitation Machine And Influence Of The Thickness Of Yoke On The Ability Of Magnetic Regulation

Compared to the electric excitation motor,permanent magnet synchronous motor(PMSM)produces magnetic field through permanent magnet,which saves the excitation device and improves the efficiency of the motor.But the air gap magnetic field of PMSM is difficult to adjust,which is the key factor that restricts the development of permanent magnet motor.Hybrid excitation machine contains both permanent magnets and electric excitation windings,and the main magnetic field of motor is generated by the interaction of two magnetic potential sources.It can regulate and control the air gap magnetic field of motor,thus improving the performance of motor.At present,the hybrid excitation synchronous motor adopts DC magnetic regulation,but the DC magnetic field will cause the asymmetry of the bidirectional excitation range of the hybrid excitation synchronous motor,and the weak magnetic capacity is lower than the increasing magnetic capacity.Based on the hybrid excitation framework,if the phase of the excitation magnetic force can be flexibly adjusted changing with the resultant magnetomotive force(MMF)to increase or decrease magnetic field,in this way,two-way magnetic range will be symmetric,which can effectively improve the weakening capability of the motor,and improve the highest speed and power density of the motor.In order to realize this idea,a dual consequent hybrid excitation synchronous(DCHES)machine with double staggered structure is proposed.In this paper,the author first introduces the structure and AC magnetic flux modulation principle of the DCHES machine,describes the migration path of the magnetic flux under different magnetic conditions,and analyzes the d-q axis magnetic field distribution through three-dimensional finite element analysis(FEA)when the permanent magnet MMF,excitation MMF,and armature MMF works respectively.Second,the equivalent magnetic circuit(EMC)model of DCHES machine is established,and the armature back electromotive force(EMF)under no-load and load conditions is calculated,in comparison with the back EMF obtained by FEA,proving the feasibility of equivalent magnetic circuit method.Then the axial flux under no-load and load conditions of different thickness of the middle yoke is calculated by FEA,and the influence of the yoke thickness on the axial magnetic field is analyzed.Besides,we calculate the back EMF of armature winding of DCHES and consequent pole permanent magnet(CPPM)machine when the whole yoke thickness or middle yoke thickness change by FEA.According to the curve of back EMF along the change of excitation MMF,we comparethe magnetic regulation ability and the symmetry of magnetic regulation of CPPM machine with DCHES machine,analyzing the influence of yoke thickness on the ability of magnetic regulation.Finally,the EMC method and the FEA method are used to calculate the armature back EMF of the middle yoke at 6mm thickness,and the EMC model is verified again.