Research On Design And Performance Improvement Of Brushless DC Motor For Refrigerator

The brushless DC motor has the advantages of simple structure,small size,high efficiency,reliable operation,etc.It has been widely used in the field of refrigerator fans.However,the key parameters such as the brushless DC motor winding are generally based on the experience of design,the inaccurate selection of the Hall sensor installation position and the large torque wave pulsation in the commutation process,thereby seriously affecting the performance of the box.This article focuses on the design and performance improvement of the three-phase brushless DC motor and single-phase brushless DC motor commonly used in refrigerators.The main tasks are as follows:(1)The development status of brushless DC motors and their application in refrigerators are expounded.The research status of brushless DC motor design and torque pulsation suppression at home and abroad is summarized.(2)The structure of the brushless DC motor control system is given.The operation principle of the brushless DC motor control system is described and the mathematical model of the brushless DC motor is deduced.For three-phase brushless DC motors for refrigerators,according to the actual engineering requirements,based on the principle of three-phase brushless DC motors,the motor parameters that meet the motor design requirements were determined.According to the established three-phase brushless DC motor parameters,a two-dimensional finite element analysis model of three-phase brushless DC motor was established using ANSYS Maxwell software,and the influence of the number of turns and the winding resistance on the mechanical performance of the motor was analyzed.The relationship between the torque characteristics of the three-phase brushless DC motor and the number of turns of the coil and the resistance of the coil was obtained by the least squares method.According to the performance requirements of the three-phase brushless DC motor,determine the number of turns and winding resistance of the motor.In order to ensure the reliable operation of the three-phase brushless DC power,the positional installation principle of the Hall sensor is discussed.In order to ensure that the Hall sensor accurately measures the rotor position,the installation position of the Hall sensor is determined through three-dimensional finite element simulation and space magnetic field measurement experiments.The finite element simulation results show that the designed three-phase brushless DC motor parameters meet the motor design requirements and the Hall sensor installation position meets the design requirements.(3)Aiming at single-phase brushless DC motor for refrigerator,the bipolar winding drive circuit of the motor was given.The reasons of the torque ripple generated during the motor commutation were analyzed.The influence of the motor inductance on the rate of change of the current in the commutation process was deduced.The back EMF,cogging torque,phase current and electromagnetic torque of a single-phase brushless DC motor were obtained through finite element simulation.In order to reduce the torque pulsation in the commutation phase of singlephase brushless DC motor,a phase-leading commutation control strategy was proposed,and the optimal lead commutation angle was theoretically deduced.The single-phase brushless DC motor for refrigerator was simulated by finite element method,and a noise test platform was built to test the running noise of single-phase brushless DC motor.The simulation results show that the proposed control strategy based on phase advance commutation reduces the torque ripple by 17.3%.The noise measurement results show that the proposed control strategy based on phase advance commutation reduces the motor noise by 1.5d B(A).Simulation and experimental results verify the effectiveness of the control strategy based on phase lead commutation.