Design of Self-excitation Power Source with Automatically Switchable Winding Number of Secondary Coil
Power supply based on small CT for electronic current transducer is stable and cheap.However,the increasing quantity of heat production of self-excitation power sources with the bus current increasing is unacceptable.This limits the usage of CT-based sources.Aiming at the defect of existing CT-based power sources,a simplified and efficient energizing method which can vary the secondary winding with bus current is proposed.The voltage division circuit consisted of metal film resistor monitors the rectified voltage and the hysteresis switch composed of voltage comparator,MOSFET and relay will change the secondary windings according to different voltage range.Experimental results demonstrate the excellent performance of this method.
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