Design Of The Rare-Earth Permanent Magnet Brushless DC Motor

The rare-earth PM (permanent magnet) brushless DC motor uses the rare-earth permanent materials of high magnetic energy product, and uses the electronic commutation technology in place of mechanical commutation. So it has a simple structure, reliable operation, small volume, light weight, small loss, high efficiency, excellent operating characteristics and so on, thus widely used in aerospace, precision instruments, industrial control and many other places where the requirements of the motor operating performance are high. So the study of rare-earth PM brushless DC motor has great significance.The rare-earth PM brushless DC motor was designed by electromagnetic design and the finite element analysis software ANSYS. In electromagnetic design the motor parameters were confirmed by circuit calculation, operating characteristics calculation, equivalent magnetic circuit calculation. The motor parameters included the main dimensions, such as the inner and outer diameter of the stator, the length of the core, the height of the permanent magnet, ande the terminal voltage of winding, the coil number of winding in series, electromagnetic torque and so on. The finite element analysis software ANSYS was used to simulate electromagnetic field of the rare-earth PM brushless DC motor, and the four primary coefficients including no-load flux leakage coefficient, calculation of the armature length, calculation of pole-arc coefficient, air-gap coefficient were calculated by the post-processing of electromagnetic field. And the four coefficients influencing the rare-earth PM brushless DC motor design were discussed. Finally the software ANSYS was used to simulate the rare-earth PM brushless DC motor’s rotor magnetized. The factors effecting the magnetizing performance including the wire diameter and the coil number of magnetizing coil, the magnetizing voltage, the selection of core material, the axial distribution of magnetic field and so on, were discussed. The primary parameters of magnetizing coil magnetized were confirmed by simulating the electromagnetic field when the magnet ring of rotor was magnetized. The magnetizing coil was made basing on the primary parameters, and the magnet ring of rotor was magnetized. The test result validated the correctness of simulation result by testing the magnetizing result.The primary parameters of motor and rotor’s magnet ring magnetized were obtained by the electromagnetic design of rare-earth PM brushless DC motor and the finite element analysis design of ANSYS. The four primary parameters in electromagnetic design were confirmed by the finite element analysis method of software ANSYS is more intuitionist than tradition calculation method. The research show that using the finite element analysis software ANSYS can shorten the circular period of permanent motor rotor’s magnetizing design, the design results are very intuitionist and exact, and it has the quite significant practical application value.