| Interior permanent magnet synchronous motor(IPMSM)is widely used in the field of drive motors for electric vehicles because of its advantages such as wide speed range,wide high-efficiency zone,high power density and low vibration and noise.With the development of electric vehicle manufacturing industry and the continuous improvement of users’ pursuit of comfort,the Noise、Vibration、Harshness(NVH)performance solution of drive motor for electric vehicle has become one of the current research focuses.Therefore,the study of electromagnetic performance and vibration noise of IPMSM for electric vehicles is of great significance and application value.To study the influence of different rotor topologies on the electromagnetic performance of IPMSM,this thesis takes the 8-pole 48-slot permanent magnet synchronous motor(PMSM)as an example and establishes finite element models of PMSM with single and double-layer permanent magnets for two types of built-in rotors.To ensure the rationality of the comparison,these two motor models are identical except for the rotor structure,and the rotor structure was optimized for the torque ripple and the cogging torque of these motors respectively and the optimized rotor punches were checked for mechanical strength.Then,the difference between these two motors was analyzed from the perspective of the magnetic circuit structure,and the dq axis mathematical model of the inductance was established.The electromagnetic characteristics of these two motors were analyzed and compared by using the finite element method.The sources of each component of the air-gap flux density as well as the wave frequency and spatial order of the radial electromagnetic force were analyzed according to the potential-permeability method and the Maxwell tensor method respectively.The finite element method was used to calculate the air-gap flux density as well as radial electromagnetic force and its harmonic content,and to analyse and compare the spatial and temporal distribution characteristics of the air-gap flux density and radial electromagnetic force of these two motors under no-load and load conditions.Two models were established,including the stator core model of the motor and the stator assembly model composed of the stator core and the hosing.And the modal vibration shapes and natural frequencies were calculated respectively to analyze whether the motor will resonate and the influence of the casing on the natural frequency.To analyze the electromagnetic vibration and noise characteristics of the two motors in this thesis,a joint electromagnetic-structure-vibration-noise simulation model was established,and the radial electromagnetic force was mapped to the harmonic response model as the excitation.The causes of electromagnetic vibration and noise were analyzed and the performance of these two motors in terms of electromagnetic vibration and noise was compared. |
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