Single-Switch Coupled-Inductor-Based Two-Channel LED Driver with a Passive Regenerative Snubber
Abstract
In this paper, a single-switch coupled-inductor-based two-channel light-emitting diode (LED) driver with a passive regenerative snubber is presented. In the proposed LED driver, the energy-transferring capacitor is not only used to step up the voltage gain but also to achieve the current balance a LED strings. Moreover, a passive regenerative snubber is added not only to recycle the leakage inductance energy but also to improve the voltage gain. As compared with the prior work, only one switch is required. Thus, the configuration of the proposed LED driver is simpler. Since the proposed LED driver has a higher voltage gain than the prior work, the turns ratio of the proposed LED driver can be lower. Thus, the magnetic core size can be reduced. In addition, both LED drivers have the same component count. Finally, the operating principle, analysis and experimental results are provided to verify the effectiveness of the proposed LED driver.
EXISTING SYSTEM :
Recently, the capacitive LED current sharing methods are presented to overcome the drawbacks of the inductive LED current sharing methods., the capacitors with the same values are employed in LED strings to achieve current balance. However, the current balancing performance is influenced by the capacitance mismatch, the capacitor current sharing circuit with the interleaved control is presented. With the help of the interleaved control of the LED circuit switches and the charge balance of the capacitors, the LED current balance can be achieved. However, the presented method needs many switches and control drivers, which results in complexity and high cost. In, a dc blocking capacitor is connected with secondary side winding of the transformer. Therefore, with the help of the charge balance principle of capacitor, the LED currents can be automatically balanced. The main power structures used in these LED drivers contain the full bridge and half bridge topologies, which are used to generate an ac current source. This method features simple current sharing technique, low cost, and precise LED current balance. However, the structures used are more suitable for high input voltage applications. It is difficult to be used in low input voltage and low power applications. Therefore, a two channel non-isolated LED driver with low input voltage and low power applications is presented as shown in Fig. 1. In this LED driver, the dc blocking capacitor is connected with one side of the coupled inductor. Thus, based on the capacitor charge balance, the two LED string currents can be balanced naturally without any additional active component and current sharing transformer used. Moreover, the dc blocking capacitor also plays a role to step up the input voltage. Therefore, this LED driver can be used in the low input voltage applications. When the main switch is turned on, the leakage inductance will store energy. When the main switch is turned off, the leakage inductance will be transferred to the snubber capacitor. Therefore, the voltage spike across the switch can be suppressed.
PROPOSED SYSTEM:
In this paper, based on the structure the active clamp circuit in the non-isolated two-channel LED driver is replaced by a passive regenerative snubber. As compared with the LED driver presented in, the leakage inductance energy of the proposed LED driver can be directly transferred to the output LEDs. Therefore, the passive regenerative snubber cannot only be used to suppress the voltage spike but also to improve the voltage gain. Under the same system specifications as shown in the proposed LED driver can use a smaller coupled inductor core size. Moreover, compared with the LED driver presented in [27], only one switch is required for the proposed LED driver. Sequentially, the operating principles, analysis, and experimental results are given to demonstrate the effectiveness of the proposed LED drive
CONCLUSION
A single-switch non-isolated two-channel LED driver with a passive regenerative snubber is presented. Based on the nonisolated two-channel LED driver, the active clamp circuit in the non-isolated two-channel LED driver is replaced by a passive regenerative snubber. With the help of the passive regenerative snubber, the leakage inductance energy can be directly transferred to LEDs. Therefore, the voltage spike across the switch can be suppressed, and the voltage gain can be improved. Also, the coupled inductor core size can be smaller. Moreover, only one switch is required for the proposed LED driver, which can simplify the circuit. To sum up, the proposed single-switch non-isolated two-channel LED driver features a high voltage gain and a simple structure.
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