A permanent magnetic actuator with scheduled stroke curve for vacuum circuit breakers

The load characteristics of vacuum circuit breakers (VCB) are very close to the output characteristics of permanent magnetic actuator (PMA). The combination of PMA and VCB facilitates the development of phase-controlled switching technology because of its controllability. The operation time dispersion of PMA is very small, but when the actuator is impacted by the change of environment or its components, its dispersion will be unfit for phase-controlled switching. A new type of actuator driving system for PMA was proposed, which was combined with sensors, embedded system and capacitor controlled by high-current power electronic devices. The iron core trajectory of PMA was measured by a displacement sensor and compared to a scheduled action curve, the environment temperature is from a temperature sensor and the current from a Hall current sensor, then compensation to displacement was made based on the adaptive control algorithm and history data in order to match the optimal stroke curve of vacuum circuit breakers. In different conditions, the test results show that the stroke curve was in keeping with the scheduled curve and the operating time dispersion of VCB meets the requirement. The new type actuator driving system can supply an easy-controlled, constant-operating- time execution unit to controlled switching.