Research On Electromagnetic Performance Of Single Phase Line Start Permanent Magnet Synchronous Motor

In the field of home appliances,single phase induction motors still occupy a large market share due to the advantages of cost and application convenience,but the existence of eddy current losses in single phase induction motor windings makes the efficiency always low.Under the requirements of industrial upgrading and environmental protection,the highly efficient permanent magnet synchronous motor(PMSM)is the development direction of single phase motors.The single phase line start permanent magnet synchronous motor(SPLSPMSM)inherits the advantages of single phase induction motor line starting,and has the advantages of three phase PMSM with high power factor and efficiency.The SPLSPMSM is studied in this thesis,the main contents are as follows:First,the theoretical analysis of the motor is performed.The stator windings of the SPLSPMSM has an asymmetrical structure,so that the armature rotating magnetomotive force has a negative sequence component.Different treatments are carried out according to the stationary state period and the starting period.In the stationary state period,the SPLSPMSM of the asymmetric structure is converted into a symmetric motor.Under the assumption that the magnetic circuit of the motor is linear,SPLSPMSM is equivalent to a two phase PMSM with positive running and symmetrical stator windings,a two phase induction motor with negative running and symmetric stator windings.The positive and negative sequence currents and phase voltages obtained by the symmetrical component method are used as the phase current and phase voltage of the positive and negative sequence equivalent motors,respectively.Positive sequence motor analysis,using three phase PMSM analysis method;negative sequence motor analysis,using three phase asynchronous motor analysis method.For the nonlinear condition of the magnetic circuit,the frozen magnetic permeability method is considered to be the same at the same time as the SPLSPMSM and the equivalent positive and negative sequence motor.During the the starting period,since the rotor winding interacts with the fundamental wave components of the positive and negative sequence rotating magnetomotive force,the generated magnetomotive force component generates a positive and negative sequence rotating magnetic field due to the asymmetry of the magnetic circuit,so the motor is no longer equivalent to positive and negative sequence motors.the interaction between the positive sequence rotating magnetomotive force component of the armature and the rotor winding is analyzed according to the starting phase analysis method of the three phase asynchronous starting permanent magnet synchronous motor.The negative sequence rotating magnetomotive force component of the armature and The rotor magnetomotive force and torque components produced by the interaction of the rotor windings are analyzed by induction motor.Secondly,based on the theoretical analysis,the influences of different parameters on the performance of the SPLSPMSM are analyzed by finite element method.Use the finite element method to analyze the squirrel-cage SPLSPMSM of the built-in magnetic circuit structure according to the starting and steady state period,change the parameters of the armature winding turns and turns ratio,capacitance,permanent magnet thickness,load,etc.,and observe the starting load capacity of the motor.Performance indicators such as starting load capacity and steady state efficiency.Thirdly,according to the deficiencies of the squirrel-cage SPLSPMSM with built-in magnetic circuit structure,the surface-mounted and wound-rotor SPLSPMSMs are newly proposed and simulated by finite element method.Finally,the d-and q-axes inductances of SPLSPMSM are analyzed.This thesis refers to the inductive formula derivation process of three phase synchronous motor.The method of solving the inductive matrix eigenvalue and eigenvector is used to derive the d-and q-axes inductances and transformation matrix of the positive sequence equivalent motor.The frozen magnetic permeability method is used to calculate the positive and negative sequence.The equivalent motor's magnetic saturation is exactly the same.The armature reaction reactance of the positive sequence equivalent motor is used to represent the magnetizing reactance of the negative sequence equivalent motor,and then the magnetizing inductance is derived.The phase inductance is calculated by the finite element method,and the d-and q-axes inductances are obtained.