| Traditional offline simulation model of brushless DC wheel motor on matlab simulink can not accurately reflect the performance of motor, this is mainly because the electromagnetic parameters such as flux, inductance and resistance are changing along with the motor operation. There are electric, magnetic and thermal field in the motor and the coupling field can influence the above parameters. The eddy current losses generated by the harmonic of the magnetic flux density in the air gap cause the rise of temperature in the permanent magnet which can make the magnetism weaken, when the temperature rises to above the Curie temperature, the demagnetization occurs, such that the flux decreases, the inductance increases. The alternating magnetic field generates core loss, the current in the winding causes copper loss, all of that will make the temperature of the stator and winding increase. The permeability of silicon steel changes as temperature arises, thus affecting the flux of permanent magnet and the inductance of the windings. The current of windings may cause the demagnetization of permanent magnet and nonlinear magnetic saturation of the stator core, which can influence the flux and inductance. The resistivity of windings rises because of the rise of temperature which makes the resistance larger, and the skin effect caused by the variational frequency of current impacts the resistance. Therefore, to establish the precise offline simulation model of wheel motor, we must analyze the variation of the electromagnetic parameters.The electromagnetic parameters are affected by temperature of motor, and the temperature distribution is inconsistent due to heat production and heat dissipation, which makes the analysis of temperature influence to electromagnetic parameters is more complicated. Taking into account that the finite element model of the motor can be set to various parts of the material properties, it can separate the influence of various parts of the material, and the paper establishes brushless DC wheel motor finite element model to analyze the impact of the various parts’ temperature characteristic to the electromagnetic parameters. the model is verified and corrected to obtain a more accurate finite element model of the wheel wheel motor through anti dragged and load test.The paper builds analytical model of brushless DC wheel motor in matlab simulink, we can see that the analytical model does not accurately reflect changes in motor performance by comparing the simulation with experimental results, and analyze the influence of the magnitude of the flux, inductance, resistance on motor performance.Use coupled finite element model of wheel motor to simulate variation of electromagnetic flux and inductance with the temperature of permanent magnets, stator core silicon steel sheet and internal temperature of the motor, and the resistance with temperature and analyze the impact of the skin effect to resistance and analyze the variation of inductance by nonlinear magnetic saturation phenomena caused by the armature winding.Based on the finite element analysis of electromagnetic flux and inductance variation with temperature of motor, the paper carries out the experimental study of electromagnetic flux and inductance variation with temperature, and the experimental study of the temperature distribution inside the motor. |
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