Research And Design Of LED Drive Power Supply Based On ARM7

Under the environment of the current energy crisis, LED which takes advantage of highefficiency and energy saving is applied more and more widely and diversely, and the LEDpower supply is developing towards the direction of modularity and intelligence. In thissubject the basic principles, structures and characteristics of linear current source andswitching current source have been studied deeply; and two different schemes are designed,the first one switching voltage source and the linear constant current source connected in series,linear DC current source is the output stage. By its small output ripple and fast response, theaccuracy of the current can be improved. The switching DC voltage source real-time adjust theoutput voltage to reduce the voltage difference of the output stage regulator transistor andimprove the efficiency of the whole system. The second scheme is switching current sourcewith a bigger ripple and high stability. The two schemes are simulated in the simulinkrespectively and through analysis and comparison, then a kind of numerical controlled LEDdrive power supply based onARM7are designed according to the second scheme.In the aspect of control strategy, to keep dynamic performance and robustness of thesystem, this subject adopt fuzzy PID control algorithm, and design the fuzzy rules table.According to technical requirements of the power supply, the design of buck converter circuitcomponents parameters are accomplished. The simulation of the fuzzy PID controlled buckconverter model in the simulink verified the correctness of the control strategies and thereliability of the system. Finally the LED drive power supply with the LPC2138as the corecontrol system is designed, the hardware design mainly includes the main circuit, samplingcircuit, infrared hardware circuit and MOSFET drive circuit and so on. Software using themodularization design method, respectively designed the main program, the AD samplingprogram, fuzzy PID algorithm, PWM output procedure, the infrared decoding program, andwireless dimmer. The test results of experiment show that theoretical analysis of converter iscorrect, the control strategy is feasible and the performance meet the design requirement.