Research On 200W LED Driver

With environmental contamination and energy source crisis are deteriorating continuously, energy conservation has become a widespread topic. As an important aspect of energy consumption,lighting is about 19% of the world's total energy consumption, so the more and more attention is given to green energy-efficient lighting. LED, a solid illuminant, has become a new kind of green illuminating product due to its distinct advantages, such as high efficiency, long life, environmental friendliness. To replace current traditional lighting by LED lighting will play a pivotal role to current energy environmental degradation and energy shortage.LED is cold light source driven by low-voltage and its performance is influenced by the environment and performance of drivers, so a special driver is needed to provide power for LEDs. Currently, the LED power supplies are suffered by several problems, such as low reliability, low efficiency, unacceptable EMC(Electro Magnetic Compatibility) performance. The research and development of high efficiency LED driver hold a strong theoretical and practical significance.Based on the analysis of LED electronic characteristic, a 200W LED driver is proposed. Key techniques involved in the LED driver are also researched, such as power factor correction, LLC resonant converter, Electro Magnetic Compatibility. Two-stage converter program is employed: PFC (Power Factor Correction) stage and DC/DC converter stage. The boost topology is adopted by PFC converter. To obtain the optimal design, PFC stage is accomplished with critical conduction mode and continuous conduction mode separately. DC/DC converter stage is accomplished with LLC resonant converter. The dual amplifier and voltage reference is adopted in current and voltage feedback to regulate the output. At first, the fundamental of critical conduction mode and continuous conduction mode PFC are analysised; the design method of each converter's key parameters is also brought forward. Secondly, the fundamental and key parameters of LLC resonant converter are analysised; the external circuit of LLC resonant half-bridge controller and the detailed parameters of the resonant network are designed; Thirdly, the factors leading to EMI(Electro Magnetic Interruption) are analysised, EMC design considerations of the driver and the reliability design of key components are also provided.At the test of the 200W LED driver, the waveforms of key points are collected and analyzed. The test results indicate that the LED driver works stably, the power factor more than 0.98, and efficiency more than 91%.