Influence Of Winding Type On Electromagnetic Thermal Performance Of Permanent Magnet Motor

Compared with electrically excited motors,permanent magnet motors have the advantages of simple structure,high power factor,and high efficiency.They have been widely used in electric drive systems such as aerospace and new energy electric vehicles.However,the slot full ratio of permanent magnet motors is power density needs to be further improved.At the same time,large winding losses not only limit the improvement of the efficiency of the permanent magnet motor,but also cause excessive temperature rise of the motor.Temperature rise will make permanent magnets prone to high-temperature demagnetization,which will affect the safe and stable operation of the motor.How to improve the performance of permanent magnet motors through winding design has become one of the key issues in the design and development of permanent magnet motors.This dissertation studies the electromagnetic and thermal performance of permanent magnet motors with two winding forms,round winding and strip winding.Aiming at the problems of low slot full ratio,large winding loss,and temperature rise of traditional round winding permanent magnet motors,combined with the characteristics of the winding structure,a comparative analysis of strip winding and round winding permanent magnet motors is carried out.According to the rated power and the size of the punching piece,the electromagnetic and thermal performance of a round winding and three different sizes of strip winding permanent magnet motors are analyzed;the transient analysis magnetic fields of the four winding types of permanent magnet motors are established respectively model,analyze and calculate armature current,winding loss,iron core loss,permanent magnet loss and efficiency map,etc.;establish an open-loop constant voltage-frequency ratio control permanent magnet motor field-circuit coupling model,and propose a constant voltage compensation based on stator voltage.The voltage-frequency ratio control method analyzes the electromagnetic torque and speed during the start-up process of motors with different winding forms,and reveals the influence of winding forms on the starting performance of permanent magnet motors.Aiming at the problem of large eddy loss in strip windings,the influence of skin effect and proximity effect on the current density distribution of strands in different windings is analyzed,and a method for winding splitting to reduce eddy loss is proposed.Study the influence of stator slot lip height and slot lip width on the eddy current loss of strip windings,and verify the effectiveness of the proposed method through simulation.Put forward the twisted-end strip winding technology,analyze and calculate the circular current and circular current loss of the proposed winding form.Establish equivalent thermal network models of permanent magnet motors with different winding forms,fully consider the distribution of winding losses,calculate the changes in the steady-state and transient temperature of the motor,and analyze the effects of factors such as winding form and strand size on the temperature of the permanent magnet motor impact of the field.