The Design Of The DC High Voltage Power Supply Based On Cable Fault Distance Measuring Instrument

The normal operation of the cable line ensures efficient transmission of power and real-time transmission of signals,it will interrupt the transmission of electricity and communications when the failure occurs.What is the most important to have an effectively repairing of the cable fault and accurately positioning fault point in order to protect the normal work of the cable line.Therefore,cable fault range finder has important application value for the cable line detection and maintenance.This design of the DC high voltage power supply mainly used in cable fault range finder,which can provide continuously adjustable DC voltage in the 0-1kV.The ripple coefficient is less than 0.1 and load adjustment rate of not more than 0.1%.The Key function units of the DC high voltage power includes four parts:the design of main circuit in the form of the forward-flyback single end,the production of high-frequency transformer,the control circuit of switch on and off,the design voltage doubler rectifier filter circuit.The device takes 12V(lithium battery)DC as input Then the DC voltage is converted into impulse wave through the circuit of a forward-flyback single end which will be input to the high frequency high voltage transformer to get 0-250V AC.Finally,the 4 times rectifier filter circuit outputs the 0?1kV adjustable DC voltage.So the difficulty of making the transformer coil will be reduced.To improve the stability of the device,the feedback voltage which can be collected by a voltage divider in the high voltage output will be compared with the given voltage to adjust the control voltage.ICM7555 controls the duty cycle and pulse width of the output pulse by the hybrid modulation to achieve voltage regulation.Further,the design of entire closed-loop control circuit makes the device has a strong resistance to external interference.The system has functions which includes over-current protecion and real-time display of output voltage to ensure safe operation of power and load.In the experimental period,all circuit units are tested in order to optimize the design.Finally,the experiment shows that DC high voltage power supply has reached the technical indicators.It has advantages of stable performance,safe and reliable,simple circuit structure,low cost.Now,it is being mass produced to meet the needs of cable fault range finder.