Optimal Parameter Analysis of Limited Angle Permanent Magnet Brushless DC Motor Operating Mechanism

A limited angle three-phase permanent magnet brushless DC (BLDC) motor operating mechanism for the 126kV high voltage vacuum circuit breaker is proposed and designed. The simulation model of motor operating mechanism is established by using the transient finite element method in according with the counter-force and the moment of inertia. The influence factors of the output mechanical characteristics is calculated and carried out, such as the rotor excitation structure, flux density, pole embrace, length-diameter ratio, turns-diameter ratio of the armature winding under the same poles etc. The simulation results indicated that the type of rotor excitation is employed the inset permanent magnet, which using the radial magnetization, the range of length-diameter ratio is 1.85 to 2.5, the pole embrace is bigger than 0.844, and the turns- diameter ratio of armature winding under the same slot is 14.28 to 23.7. So a larger air-gap flux density about 0.9T can be obtained, and the output mechanical properties parameters (such as output torque, speed and angle) meet with the requirement of circuit breaker.