| The permanent magnet brushless DC motor(PMBLDCM)used as an in-wheel motor are widely used in many kinds of vehicle models due to its high efficiency and flexible driving mode,especially the electric bicycle(E-Bike).The application of electric motor makes the noise of electric bicycle less than that of other means of transportation,which leads to the lack of warning of its noise.The electromagnetic noise is the main source of the motor noise,so it is necessary to explore the electromagnetic noise of PMBLDCM.(1)Analytical modeling and analysis of electromechanical magnetic wave of PMBLDCM used as an in-wheel motor in full working condition.The rotational speed and current double closed loop control model of PMBLDCM is established.The current of the motor in full working condition is obtained.The analytical model of the air gap magnetic field under both steady and unsteady conditions is established by applying the magnetic potential multiplied with the complex relative permeance.And the analytical model of the electromagnetic force wave is established by the maxwell stress tensor method.The electromagnetic finite element model is established,the air-gap magnetic field and electromagnetic force wave of the motor are simulated.And the accuracy of the analytical model is verified.The results of research indicate that the main frequency components of the current are(6h±1)f_c in the low frequency band and kf _s±(6h±1)f_c near the switching frequency.The spatial order characteristics and the frequency characteristics of the air-gap magnetic field and electromagnetic force wave are the same under steady and unsteady conditions.(2)Modeling and analysis of multi-physical field of electromagnetic noise of PMBLDCM used as an in-wheel motor in full working condition.The modal test of motor rotor assembly and end cap is carried out,and the modal of motor is calculated by finite element method.The prediction model of electromagnetic vibration and electromagnetic noise are established,and the electromagnetic noise characteristics of the motor in full working condition are simulated and analyzed.The influence of eccentric fault on electromagnetic noise is analyzed.The influence of Doppler effect on electromagnetic noise of the motor with external rotor structure is analyzed.The results of research indicate that the peak of electromagnetic noise under different working conditions occurs at order138,which is the result of current harmonic field effect.Eccentricity will affect the electromagnetic noise characteristic of motor.The electromagnetic noise emitted by external rotor motor during rotation exist special side frequency order.(3)Experimental study on no-load back electromotive force and electromagnetic noise of PMBLDCM used as an in-wheel motor.The analytical model and the finite element model of the no-load back electromotive force of the motor were established.The accuracy of the air-gap magnetic field analytical model and the finite element model of the motor were indirectly verified by the no-load back electromotive force test.The experiment of electromagnetic noise collection is carried out.The electromagnetic noise under different working conditions is collected,which verifies the accuracy of the multi-physical field model.The results of research show that the peak of electromagnetic noise under different working conditions occurs at order 204,which is the result of permanent magnetic field effect.When the motor under an unsteady state,the peak of electromagnetic noise occurs when the electromagnetic noise of order 204 passes through the first resonance zone. |
