Duty-Ratio-Control-Aided LLC Converter for Current Balancing of Two-Channel LED Driver

Abstract

Duty-ratio-control-aided LLC converter for current balancing of two-channel light-emitting diode (LED) driver is proposed and analyzed. Conventional current-balancing methods have the limitation on the power density and losses from additional components. With the aid of duty ratio control of an LLC converter, the proposed driver does not require any additional component. The total output current is controlled with the frequency modulation, and the duty ratio control is added to obtain current balancing of each LED channel. The advantage of the proposed method is the high power density and high efficiency. Also, it does not affect design procedure of a conventional LLC converter. The prototype of two-channel LED driver with 400-V input and 150-100-V/0.3- A output for each channel verifies the effectiveness of the proposed driver.