| As the core component of the electric driving system of new energy vehicles,driving motor plays a vital role in the performance of vehicles.Affected by the price of rare earths,the cost of permanent magnet synchronous motors widely used new energy vehicles remains high.However,the synchronous reluctance motor does not need to use rare earth permanent magnets,which greatly reduces the cost of the motor and has high reliability.Therefore,this article analyzes and designs a synchronous reluctance motor for driving a certain miniature passenger car.First of all,based on the vehicle dynamics model,this paper analyzes the force of the vehicle under various working conditions,and calculates the vehicle’s dynamic index based on the actual parameters of the target vehicle.According to the driving demand,the performance of the motor is determined and a preliminary design of the synchronous reluctance motor based on the general theory of motor design,including the determination of the number of motor pole pairs,slot-pole coordination,winding form is carried out.And this paper uses the magnetic circuit method to calculate the relevant size of the stator slot and the optimal split ratio.Secondly,this paper analyzes the rotor structure of synchronous reluctance motor and the principle of torque generation,respectively analyzes the magnetic circuit of d-axis and q-axis,deduces the torque formula,and analyzes the factors affecting the torque of synchronous reluctance motor according to the formula,and puts forward the basic principle of designing synchronous reluctance motor.Then,this article analyzes the generation mechanism and influencing factors of the torque ripple and torque density of the synchronous reluctance motor.Aiming at the torque ripple,the positive and negative ripples are offset by each other to reduce the total torque ripple.Based on this idea,the calculation formula of the rotor magnetic barrier angle suitable for different slot poles and different magnetic barrier layers is derived to reduce the optimization time.The effects of the number of magnetic barrier layers,asymmetric rotor structure and stator gear cutting on torque ripple are studied.The effects of the number of magnetic barrier layers,asymmetric rotor structure and stator teeth cutting on torque ripple are studied.Aiming at the torque density,the core is to reduce the d-axis reluctance and increase the q-axis reluctance.The effects of magnetic barrier occupying capacity,radial magnetic rib and tangential magnetic bridge,slotting at the top of rotor and adding ferrite on torque were studied respectively.Based on the analysis results,a multi-objective genetic algorithm is used to optimize various parameters of the motor.Finally,this paper calculates the loss,efficiency and power of the motor,checks the mechanical strength of the rotor,analyzes the heat transfer process of the motor,and simulates the temperature field.The motor bench test is used to test the performance of the motor and the test error is analyzed. |
