Magneto-thermal Coupling Analysis And Optimization Efficiency Of High-speed Permanent Magnet Brushless DC Motor

With the energy conservation requirements continue to increase, high speed and high efficiency motor is the inevitable trend of development of China’s motor industry. The motor running at high speed resulting loss, temperature rise, low efficiency, and the life of the motor has a great impact on reliability, this article takes the ultra-high-speed micro drilling motor spindle interior permanent magnet brushless DC motor design for example, from the the efficiency optimization point of view of high-speed permanent magnet brushless DC motor prototype thermal magnetic coupling analysis and efficiency optimization, discover to improve high-speed permanent magnet brushless design theory and method of DC motor efficiency.The main work of the paper include:First, to described high-speed permanent magnet brushless DC motor structure, working principle and characteristics, Analysis of Electric spindle with high-speed permanent magnet brushless DC motor design features. Consider the protection of the rotor permanent magnet, the high-order harmonic of a high temperature alloy steel of high strength non-magnetic inclusions in the outer surface of the permanent magnet, effective shielding of the air-gap magnetic field, to reduce eddy current loss of the entire rotor and cooling are very favorable; high-speed spindle performance with the amount of interference and influence, to meet the design needs of high-speed spindle, the amount of interference with the motor rotor and spindle is analyzed and calculated. In addition to the field-circuit finite element method, the electromagnetic design parameters were calculated, tentatively set the overall design of the high-speed permanent magnet brushless DC motor.Secondly.set a high-speed permanent magnet brushless motor field circuit coupled model, to analysis the motor transient two-dimensional electromagnetic field, to obtain the run-time of the motor no-load and load characteristics; consider high-order harmonics and rotation of magnetization on the high-speed motor stator iron losses, the stator in different parts of the calculation of the equivalent flux density, and by means of harmonic analysis to calculate the amplitude of the flux density of different frequencies;Based on Bertotti discrete iron loss calculation model to analysis alternating magnetic field waveform iron loss, the loss of high-speed permanent magnet brushless DC motor is analyzed and calculated. According to the temperature field theory, the use of the Ansoft and Workbench finite element analysis software to build a high-speed permanent magnet brushless DC motor magneto-thermal coupling finite element analysis model, to analysis the key components of the motor stator, rotor, permanent magnet transient two-dimensional temperature field. The results show that:The temperature of the stator highest point of the stator tooth tip, the rotor portion temperature is higher than the temperature of the stator core; through research different sheath materials and thermal radiation on the motor temperature rise.Finally, in order to meet the design requirements of ultra-high-speed spindle permanent magnet brushless DC motor, from the perspective of the structural design of the motor,explore to reduce losses and improve efficiency methods.Consider from motor winding diameter and the length of stator and rotor core to reduce the stator winding copper consumption, to increase motor efficiency; also studied the impact of the loss of the core material of the stator and rotor of the motor. Motor efficiency as the optimization objective, the use of genetic algorithm to optimize the design of a0.6kW,200,000r/min high-speed permanent magnet brushless DC motor, effectively reducing the motor core loss and improve the operating efficiency of the motor.