High efficiency half-bridge converter with transient current build-up technique

Abstract

Recently, LED lights are used in various lighting applications due to their excellent characteristics. To increase the efficiency of the LED system, a high-efficiency LED driver is required. In addition, to reduce the production cost, a single LED driver needs to operate with wide output voltage conditions. Thus, LED driver needs to not only achieve high efficiency but should also operate in a wide output voltage. To satisfy the requirements, a high-efficiency half-bridge converter with a transient current build-up technique is proposed in this paper. The proposed converter employs an active clamp snubber on the rectifier diode of the half-bridge zeta (HBZ) converter. The auxiliary switch turns on momentarily in the transient region and the primary side current is built up to shape a rectangular current waveform. As a result, in the proposed converter, high efficiency can be obtained thanks to the low voltage stress on the diode and small RMS current. The proposed converter was verified through a 120-240W prototype with 400V input and 30-60V/4A constant current output.