A 1-MHz Resonant LED Driver With Charge-Pump-Based Power Factor Correction

Abstract

This article presents the design and implementation of a resonant LED driver. The driver structure comprises a charge-pump-based power factor correction (PFC) converter and a class-DE dc–dc converter. The PFC converter uses a charge-pump circuit that achieves PFC inherently. The class-DE converter comprises a series-resonant tank and a high-frequency transformer. Both the converters share the same half-bridge and gate-driving circuit, resulting in an integrated-stage architecture. The inherent PFC operation limits the controller responsibility to the regulation of the output current. The overall converter operates with zero-voltage switching (ZVS) across the entire load range, allowing for increased switching frequencies with reduced switching losses. A 1-MHz prototype using wide bandgap (WBG) switching devices is built and tested. The prototype delivers up to 42 W of output power, with a power density of 1.8 W/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . A power factor of 0.99 and a total harmonic distortion (THD) of 6% are achieved, with an efficiency of 90% at full load. The input current harmonic magnitudes are well within the IEC 61000-3-2 standard limits for class-C devices. Burst-mode (ON/OFF) modulation is used for output current regulation between 20 and 900 mA for dimming functionality.