Design On Power Supply System Of Permanent Magnetic Actuator For Vacuum Circuit Breaker

With the development of power system in China,the demand of electrical production is becoming more rigorous.As an important part of power system,vacuum circuit breaker is no exception.Nowadays,the vacuum circuit-breaker is turning toward to the high voltage,the miniaturized direction develops,in view of this tendency,domestic and foreign electric power profession design new type of vacuum circuit-breaker.At the same time,the development of new vacuum circuit-breaker requests the adequate reliability,the low power consumption,the miniaturized of the electricity source.As the power system for vacuum circuit breaker, permanent magnetic actuator,which is principally accomplishes the function of opening, closing operation,is mainly used in design of new type vacuum circuit-breaker.In the system, power supply uses the switching power supply for the electrolytic capacitor charging. Electrolytic capacitor transfers the stored energy to the coil of the system.And the design and the reliability of power supply in permanent magnetism system is core technology which can spread into practical application.Firstly,this paper describes the working principle and the control mode of the forward, fly-back,half-bridge and full-bridge DC-DC converter.According to actual situation,fly-back converter has been chosen as a changing power.Through the formula of fly-back converters deducted for dynamic state process with large capacitive loads,it fully explains the superiority of the current power supply.Furthermore,theoretical basis is given for the design of capacitor charge power.According to the method of getting the power on line for the system,power induction coil is used.The work principle of power induction coil is analyzed and according to such a special condition,the empirical formula has been improvement.Based on the theoretical,a new method of design is proposed in this paper.In hardware part,the arrangement of power system,changing power circuit is designed based on design requirement. The major parameters of changing power and induction coil are shown in the paper.Through theoretical analysis,the prototype power system is installed and adjusted.The working state of power induction coil and system protection circuit are checked;key waveforms of charging power supply,change of voltage on the capacitor and ripple of voltage are shown.We can draw a conclusion by experimentation that fly-back converter is suit for charging capacitors with very low input voltage.The validity and reliability of permanent magnetic power system are proved.