A Reliable and Controllable Motor Actuator Without Permanent Magnetic for 40.5 kV Vacuum Circuit Breakers

In order to solve the disadvantages of long start-up time and demagnetization of the traditional permanent magnetic (PM) actuators, this article presents a high reliable and controllable novel motor actuator without PM, which includes driving motor and its control circuit. The proposed driving motor is similar to the switched reluctance motor, which has the advantages of small rotational inertia and fast start-up. The difference is that there is an auxiliary coil, which is placed between the two-stator sets, can be energized by controllable direct current to adjust the air-gap flux density and then the output torque of motor and the velocity of movable contact are easier to control. Furthermore, a prototype of the novel motor actuator has been developed according to the analysis and calculation results of the dynamic characteristics of 40.5-kV vacuum circuit breaker (VCB), and which is tested on the platform in conjunction with a 40.5-kV VCB prototype to showcase the success of the proposed motor actuator and its control method.