Analysis and design of a multi-channel constant current light-emitting diode driver based on high-frequency AC bus

To obtain sufficient luminance and achieve higher reliability, light-emitting diodes (LEDs) are usually arranged in parallel strings in many high-power applications. Since current imbalance should be avoided among the parallel LED strings, a multi-channel constant current LED driver based on high-frequency AC bus is proposed in this study. The proposed driver is composed of one resonant inverter followed by passive resonant rectifiers according to the number of LED strings. The amplitude of the high-frequency AC bus voltage is regulated by the resonant inverter and each LED string is individually powered with constant current by its corresponding passive resonant rectifier. The proposed driver is characterised by low cost and high efficiency. Finally, a prototype is built to verify the performance of the proposed driver.