Design And Optimization Of Multiplexed Output Intrinsically Safe Power Supply For Coal Mine Based On NCP 1207

The coal mine’s complex conditions,tough environment,and the severe power supply voltage fluctuation,as well as the traditional linear power supply’s large volume and low efficiency,leads to the dissatisfaction of underground monitoring and inspecting,sensors and other low-voltage equipment’s power demand.At home,after decades’ development of the intrinsically safe power supply,the intrinsically safe theory and technology become more mature,which have a more significant impact on coal mine safety production,so researching a kind of intrinsically safe power supply with reliable performances has important practical value and significance.In this paper,the PWM control chip NCP1207 with soft-start and quasi-resonant functions is selected.With the flyback topology as the core,the intrinsically safe power supply rectification filter circuit,PWM control circuit,multiple output circuit and dual over-voltage over-current protection are designed.The important components of the circuits are also selected and optimized.Finally,the intrinsically safe power supply issimulated(Pspice simulation),going through experimental verification and spark ignition test.The output of the circuit and the waveform of the switch are measured and analyzed.The intrinsic safety performance of the circuit is also verified,and then comes to the following conclusions:(1)The components used including high frequency transformers are calculated and compared one by one to ensure their compatibility with other components and the stability of actual work.(2)The designed double over-voltage and over-current protection circuit simplifies the structure,and the actual protection effect has also been verified by tests and can meet the requirements of the intrinsically safe circuit.(3)The simulated and actually measured waveforms prove the rationality of the circuit design and can work reliably under actual conditions,and the waveform values can reach this design index.(4)The spark energy of the intrinsically safe power supply designed this time is not enough to ignite the mixed explosive gas,and its performance is proved to meet the requirements of intrinsic safety.