Research On Mining Intrinsically Safe Switching Power Supply

Intrinsically safe power supply is mainly used for monitoring and communication equipment in mines.It is a key component of mining electrical equipment and plays a vital role in coal mine safety production.Comparing with the mining linear power supply,the mining switching power supply has many advantages such as smaller size,lighter weight and higher efficiency,so it has a broad application prospect.For the traditional intrinsically safe switching power supply,there are some problems such as small output power and slow dynamic response of the circuit and so on.The paper conducts in-depth research on the intrinsically safe switching power supply for mining based on DART(Dynamic Arc Recognition and Termination)technology.The following research work has been done:For the measures of output protect,traditional intrinsically safe switching power supply adopted the voltage limiting and current limiting,so there were problems of slow response and low output power.The paper used DART technology to detect circuit dynamic parameters,current rate of conversion,and to predict circuit failure status in advance.When the rate of current conversion exceeded the critical value specified by the system,the system transitioned to a safe state quickly.Because the response time of the power supply was greatly shortened,the arc energy generated at this time was much smaller than the minimum ignition energy(MIE).Then the paper analyzed the basic principles of DART technology in detail,and further discussed the Power-i system formed by the development of DART technology.On the other hand,some key equipment in the coal mine needs uninterrupted power supply.So a mining intrinsically safe switching power supply,only output was intrinsically safe,was designed.The wide voltage input range was from 60VAC to 180VAC,and the output was 18VDC/1.3A.The whole system adopted the online uninterruptible power supply structure,the front input part was a Flyback converter,the energy storage part adopted the lithium battery,using bidirectional DC/DC converter to exchange energy with the bus bar.And the output part adopted a Buck-Boost converter.In matlab software,the control loop compensation design of the discrete system was carried out,and the circuit was simulated in Simulink software.At the last,experimental prototype was produced to verify the circuit design.The protection circuit was designed based on DART technology,and the circuit had the soft start,the self-recovery and other functions.The circuit parameters were simulated in Pspice simulation software,also the experimental prototype was made.For the resistive load,the rated output was 18VDC/1.3A,and the circuit would be protected within 5?s only when faults occurred.The arc energy was 0.1073mJ,which was much smaller than the minimum ignition energy and met the design requirements.