一种基于晶闸管的串联LED故障保护电路的设计

Design of series LED fault protection circuit based on thyristor

为了避免LED串联回路因某盏灯故障断开而导致所有LED都熄灭,利用单向晶闸管、稳压二极管以及热敏电阻的工作特性,设计了具有断路保护与过热保护功能的保护电路。将设计的保护电路进行实物验证,证实了本方法的可行性。实验结果表明:保护电路会存在电流突变且仅适用于LED盏数多的电路,加入限流电阻可抑制电流突变,但需以消耗功率为代价。为了更好地抑制电流突变,设计了具有电流负反馈的闭环控制系统,在MATLAB/Simulink中搭建模型进行仿真,仿真结果证实了PWM变换器UPE可根据负载变化自动调节电流值,能解决电流突变且无功率损耗,具有一定的工程应用价值。

In order to prevent the LED series circuit from going out due to the failure of a certain lamp,the protection circuit with the function of circuit break and overheating protection is designed by using the working characteristics of one-way thyristor,voltage stabilizing diode and thermistor.The feasibility of this method is verified by the physical proof of the designed protection circuit.The experimental results show that the protection circuit has a current mutation,and it is only suitable for the circuit with a large number of LEDs.The addition of current limiting resistor can restrain the sudden change of current at the cost of power consumption.In order to restrain the current mutation better,a closed-loop control system with current negative feedback is designed.The model is built in MATLAB/Simulink for simulation.The simulation results show that the UPE of PWM converter can automatically adjust the current value according to the load change,and can solve the current mutation without power loss,which has a certain engineering application value.