Research On MCU - Based Digital LED Driver

Under the background of global energy shortage, the traditional lighting sources will be replaced by LED lighting source, which has the advantages of green environmental, high efficiency and long life. With the development of intelligent lighting technology, the LED products with digital controlled are widely used in public lighting and smart home. So it is significant to study the LED driver with digital control.Firstly, according to the electrical characteristics and the driving requirements of LED, the two stage circuit configuration is used. The first stage is the power factor correction(PFC) circuit using Boost topology and the second one is a DC-DC converter using Flyback topology. Both the PFC and Flyback circuit are controlled by the low-cost ARM chip STM32F103 RB. PFC circuit is controlled by digital average current control method and the DC-DC converter is control by the improved average current control method. Secondly, according to the operational principle of the circuit, mathematical models of Boost-PFC and Flyback circuit are both set up based on small signal model analysis and switched networks average model. According to these two mathematical models, the digital controllers of Boost-PFC circuit and flyback circuit are designed respectively under the steady condition. PSIM software is used to simulate Boost-PFC circuit and flyback circuit, simulation results show that the above theoretical analysis is correct and the design of circuit is feasible. Finally, the actual prototype is built by designing hardware circuits and software algorithms, experimental results reveal that the theoretical analysis is correct.