Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
An LED Driver With Dynamic High-Frequency Sinusoidal Bus Voltage Regulation for Multistring Applications Abstract This paper presents an LED driver circuit consisting of resonant inverter and several LCL-T resonant rectifiers. In order to obtain sufficient luminance and achieve high reliability, light-emitting diodes (LEDs) are usually arranged in parallel strings in many high-power applications. Light-emitting diode (LED) are high efficiency and long lifetime when compared with the existing conventional lighting source. Since current imbalance should be avoided among the parallel LED strings, a multichannel constant current LED driver with dynamic highfrequency sinusoidal voltage regulation is proposed in this paper. The proposed driver is composed of one resonant inverter and several LCL-T resonant rectifiers. The number of the rectifiers equals to that of the LED strings. The rectifier whose output current is sensed and closed-loop controlled is called master rectifier and all the others slave rectifiers. The resonant inverter is used to convert dc voltage into high-frequency sinusoidal bus voltage and the LCL-T resonant rectifiers are included to drive LED strings with constant current. The amplitude of the high-frequency sinusoidal bus voltage is dynamically regulated to ensure the output current of the master resonant rectifier to be constant by a closed-loop controller. Since the output current of the slave rectifier is linear with the amplitude of the bus voltage as the master rectifier, there are not any auxiliary circuits included in the slave rectifier while the output current balancing is achieved. Finally, a 200-W prototype with one master and fifteen slave rectifiers is built to verify the performance of the proposed driver Existing Methods and It’s Drawbacks 1. Active method Constant current regulator Linear type Switched type Drawbacks of Active Method Linear type-High power loses and poor efficiency Switched type-complex and high cost 2. Passive current Balancing method Resister Capacitor Hybrid passive current balancing method Drawbacks of Passive Method Resister-Ballast resistor in series with each LED string to minimize the current difference will lead to large unnecessary loss of energy Capacitor-Required more transformers Hybrid passive current balancing method-High cost, limited output and seven passive components needed to achieve one output channel Proposed Method LED driver circuit consisting of one resonant inverter and several LCLT resonant rectifiers. Advantages of proposed system Full load and light load efficiency are maximized. Protects the system during full load operation. It can easily achieve the multichannel constant current output. High efficiency due to its soft switching characteristics. LED has long life time when compared with the existing conventional lighting. Applications Energy consumption. Automotive lighting. Architectural lighting. Display backlighting. LED based street light. Low loss led drive improves a system green foot point by boosting efficiency and battery life.