| High torque density permanent magnet motors are the core and key components of electric drive systems for advanced equipment such as electric vehicles,robots,and computerized numerical control machine tools.Compared with traditional permanent magnet motors,permanent magnet vernier(PMV)motors operate on multiple magnetic field harmonics and have higher torque density,making them an important development direction for advanced electric drive systems.However,the application of PMV motors has been limited by the significant core losses caused by the magnetic field modulation effect.Therefore,based on the principle of magnetic field modulation,the coupling relationship between stator core loss and magnetic field harmonics passing through the airgap and magnetic leakage without passing through the airgap was studied in this thesis.A method for analyzing the stator core loss of PMV motors based on the inherent magnetic field modulation effect and special modulation pole structure using flux as a bridge has been established.The mechanism of the influence of magnetic field harmonics and leakage on stator core loss can be revealed by this method.On this basis,design guidance is provided for the suppression of motor stator core loss,achieving a balance between high torque density and low loss of the motor.Furthermore,this method was used to guide the design of an flux barrier motor and altered slot motor to achieve the effect of suppressing stator core loss,verifying the correctness of the proposed method.The research results of this thesis mainly include the following aspects:1.Based on the classical Bertotti core loss separation formula,the core loss in different parts of the stator was calculated.The flux density of the stator core was analyzed to determine the main source of stator core loss.The impact of the harmonic components of the stator core magnetic field on stator core loss was determined through harmonic analysis of the flux density.In addition,by decoupling the stator tooth magnetic field,the classical Bertotti core loss formula was further derived to reveal the mechanism of stator core loss from the perspectives of permanent magnet and armature magnetic fields.2.Considering the leakage generated by the armature magnetic field,an equivalent magnetic circuit model was established,and the airgap harmonic and leakage flux were expressed using magnetic flux balance.Expressions for the airgap harmonic and leakage in the stator teeth were derived,and their contributions to the stator tooth flux were calculated.Then,according to the impact on the electromagnetic performance of PMV motors,these two parts of flux were carefully classified,and based on this,a stator core loss analysis method using flux as a bridge was established.3.Based on the proposed stator core loss analysis method,a concept of stator loss suppression was established by suppressing non-working airgap harmonics and flux leakage.Two low stator core loss PMV motor topologies were designed,and the reasons for the decrease in stator core loss were analyzed from the perspective of suppressing non-working stator tooth flux.4.A comprehensive comparison was made between the original motor and the newly designed flux barrier motor,as well as several key electromagnetic properties of the altered slot motor.Through comparison,it was found that the stator core loss of the flux barrier motor and the altered slot motor decreased significantly,and the average torque was not affected.In addition,flux barrier motor can also reduce rotor loss,while altered slot motor’s rotor loss remains basically unchanged.5.Two PMV experimental prototypes were manufactured,including the original motor and the newly designed flux barrier motor.A testing platform was built,and important performance tests such as back electromotive force,electromagnetic torque,and loss were conducted through no-load and load experiments to verify the effectiveness of stator core loss analysis and suppression methods. |
PDF Full Text Request