Study On The Key Technologies Of High-power Led Control Based On DSP

Nowadays, the problem of energy and environment is becoming more and more serious, thus high-power LED in the field of lighting is attracting people’s attention. LED, a new type of semiconductor solid-state light sourece.It has the characteristics of high efficiency, energy saving, environmental friendly, long service life, flexible control, etc. Since it was invented in1960s, it had been widely applied in the area of lamps, traffic lights, large LED display, LCD backlight lamp, what’s more, the city landscape lighting and road lighting applied LED technology recently. The high-power and high brightness LED products can’t reflect the lighting advantage of LED in the lighting market nowadays. The technology of LED illumination is the main point the field, which mainly reflected in the efficiency, the control accuracy, and drive capability, reliability and so on.Based on the chracteristics of luminescence of LED, analyst of several commonly used current drive technologys on high-power LED has been made in terms of electricity and luminescence of high-power. Considering efficiency, precision of constant current and heat dissipation as the requirement of energy saving and high stability of high light efficiency in today’s LED technology, a high-power LED is designed which is driven by pulse constant current based on DSP control. The main circuit used SEPIC topology and pulse constant current drive mode. It has PWM dimming function and is suitable for driving high power LED lamp string. The input voltage range is12～24V, and current driving range is0～1.6A. Besides, a single strand of adjustable current is0～200mA and constant current control precision is within3%.The main content of the research includes:building mathematical modeling of SEPIC circuit under the environment of Matlab and verifying whether the parameters selected in the actual circuit meets the design requirements; establishing Sepic closed loop PID control model and a pulse constant-current driver model based on Sepic model and online tuning of PID parameters; giving voltage reference, current a soft start way, eliminating the influence caused by impulse voltage and current power in the LED lifetime; debugging DC/DC converter design parameter selection, the hardware circuit and the whole system. Control system uses32bit fixed-point DSP chip TMS320F28035of Ti to realize the control of the high power LED lamp string.Finally, we tested the system and analyzed the experiment results, and summarized the lessons of the design to propose the forecast of extension control in the area of high-power LED lighting.