| The interior permanent magnet synchronous motor(IPMSM)is widely used in pure electric vehicles because of its advantages such as strong weak magnetic ability,wide range of expa Nsion speed and high mechanical strength.There are a lot of harmonic currents in the armature winding of the motor under deceleration condition.The harmonic current will deteriorate the vibration and noise performance of the motor.Therefore,it is of great significance to study the electromagnetic characteristics of motor and optimize the motor under the condition of feedback braking.(1)The analytical analysis of permanent magnet synchronous electro-mechanical force based on equivalent magnetic network method.Firstly,the magnetic network solution model of slotless motor is established according to the magnetic map of slotless motor.The node voltage method is used to solve the magnetic circuit model with B-H curve of fixed rotor core as co Nstraint.Secondly,the influence of stator slots on the magnetic field is co Nsidered by using the complex air-gap ratio permeability function.Finally,the accuracy of the analytical results is verified by the finite element results.The results show that:the spatial order of no-load slotless magnetic field and the polar logarithm p of the motor meet the relation of(2n-1)p,the frequency of no-load slotless magnetic field and the mechanical rotation frequency of the motor meet the relation of 4(2n-1)f,n∈1,2,3....Stator slots will increase the order characteristics of magnetic field,but will not affect the frequency characteristics of magnetic field.The frequency of the tra Nsient current under the feedback braking condition satisfies the relatio Nship between f_s-2f_c,f_s-4 f_c,f_s+2 f_c and f_s+4 f_c,and the amplitude of the radial electromagnetic force satisfies the relatio Nship between f_c,2 f_c and 3 f_c.In the formula,is the f_c current base frequency,and f_s is the switching frequency of the inverter.(2)Simulation analysis and experimental verification of air gap magnetic field and electromagnetic wave.Firstly,the electromagnetic simulation software Jmag was used to simulate the motor with a speed of 4200 r/min,a current of 70 an initial angle of3.75°.Secondly,the magnetic field analysis results and finite element results are compared and analyzed.Finally,the time and precision of magnetic field analysis are compared with that of finite element analysis.The results show that the RMS value of radial airgap flux de Nsity can reach 95%and the accuracy of analytical model is good.The time of armature reaction is only 1/12 of that of finite element analysis.The equivalent magnetic network model proposed in this paper has reached more than 92%accuracy,and the time co Nsumption has been reduced by at least 20%,which has realized the purpose of this paper.(3)Multi-objective Optimization of feedback braking Force of built-in PERMANENT magnet Synchronous Motor.In the electromagnetic simulation software Jmag parametric modeling of the motor with permanent magnet length,the width of the permanent magnet motor,the Angle of the permanent magnets,magnetic bridge i Nsulation motor structure parameters such as width,the stator slot width as the optimization parameters,with motor to weaken the cogging torque of the motor,reduce the back emf harmonic amplitude,weaken the motor torque ripple,12 times to reduce electromagnetic force amplitude as the optimization goal.The multi-objective optimization of the motor is carried out by mea Ns of joint simulation.The results show that the stator tooth width has the greatest influence on the optimized target tooth torque,harmonic reverse electromotive force,torque fluctuation and average torque,and the air gap length has the greatest influence on the 12-fold frequency electromagnetic force.Multi-objective optimization of motor can be realized by mea Ns of joint simulation. |
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