Research On Permanent Magnet Linear Motor Operating Mechanism For Vacuum Circuit Breaker

With development of the intelligent electrical network by all countries, intelligent electrical apparatus are attracted more and more attention vacuum circuit breaker, as a key electrical switch element in transmission and distribution system, plays double roles in both control and protection. And its intelligentization receives much concern in recent years. Operation mechanism has conclusive effect on the reliability and intelligentization of vacuum circuit breaker. Permanent magnet linear motor operation mechanism is designed for 40.5kV vacuum circuit breaker with which the model number is TD-40.5/1600-31.5. This new type of operation mechanism provides a guarantee for intelligentization of the Vacuum circuit breaker.Based on the operating feature of vacuum circuit breaker, this paper puts forwards a new type of control mechanism:motor drived operating mechanism is proposed in this paper. Permanent magnet motor operating mechanism of vacuum circuit breaker was designed, based on the analysis of dynamics of operating mechanism. Force characteristic and motion quality was reduced, which as a basis to detemine motor performance, guide the design of motor. Combinating the characteristic of shot time and big force of vacuum circuit breaker, the whole structrue of permanent magnet linear DC motor, electromagnetic load, the length of air gap, the type of secondry slot, and the length of permanent magnet are designed. Electromagnetic load distribution of permanent magnet linear motor is analyed by finite element method to make sure the rationality of motor structrue. Meanwhile this paper combines local perturbation method. The effect of power load, cogging ratio and thickness of yoke on motor performance is analyzed. And the problem of motor design is adjusted, obtained the better design project. Because of the characteristic of shot time and fast operation of vacuum circuit breaker, permanent magnet linear motor is working at starting and braking, therefore dynamic characteristics is nesssery to analye and calculation. Dynamic math model of permanent magnet linear DC motor is analyed, the dynamic process of motor is calculated, and the relationgship of current, speed, displacement and time are obtained. Combining the relationship of motor secondry and moving contact, the motion characteristics of moving contact are calculated.The analysis results prove that permanent magnet linear motor operation mechanism is reasonable. And it is fit for the capability requirement of vacuum circuit breaker.