GaN HEMTs-based compact power factor corrected 96.1% peak efficiency LED driver with gate assisted circuit

LED drivers of present day demand high power factor (PF), high power efficiency, low total harmonic distortion, very low electromagnetic interference and high reliability but still struggling with low operating frequency and voltage, low efficiency, large size, lack of fully soft switching, low reliability, high cost, shoot-through and switching oscillations. In this paper, an LED driver is presented for high input voltage with low bus voltage that features very low noise, low total harmonic distortion (THD), high PF and high power efficiency by using fully soft switching mechanism, i.e. the negligible switching losses. The driver is based on two boundary conduction mode (BCM) boost circuits with common inductor that perform natural power factor correction and enhance the reliability of proposed driver. For mitigation of switching oscillations and shoot-through, a novel gate assisted circuit (GAC) is embedding by performing the mathematical analysis and modeling for shoot-through in half bridge configuration. Furthermore, the proposed driver transformer has two independent secondary windings with coupled inductor to independently drive two separate strings of LEDs. The experimental results demonstrated THD of 11.2%, PF as high as 0.99, 96.1% peak power efficiency under full load, bus voltage 410 V, fully soft switching with very small noise.