Stepdown LED drive circuit based on active ripple compensation and current square control

HU Chenglong，XUE Lingyun
（Department of Automation，Hangzhou Dianzi University，Hangzhou  310018，China）

Abstract： The ideal way to drive LED is constant current driving， and the electrolytic capacitor for filtering is adopted in output terminal， but the lifespan of electrolytic capacitor cannot match well with the LED′s Peak current control is a commonly used control mode to realize the constant driving for LED， but peak current control can only control the peak current which flows through the LED and can not precisely control its average current， thus the luminous efficiency and reliability of LED are greatly affected Aiming at solving these problems， the active ripple compensation structure omitting the filter capacitor and the current square control technique were applied in LED′s driving circuit Based on the average current， controlled by the current square control technique and the current ripple compensated by the active ripple compensation structure， the working principle of the driving circuit was researched and analyzed， and the simulation based on PSIM60 and the physical simulation was carried out at last The simulation results indicate that the current square control technique can precisely control the average current， and the active ripple compensation structure can fully compensate the current ripple which results from omitting the filter capacitor and makes the LED′s current approximately const
Key words： LED driving circuit; stepdown; active ripple compensation; current square control