Inductive decoupling-based multi-channel LED driver without electrolytic capacitors

Light-emitting diode (LED) drivers in outdoor street lighting applications suffer from short-lifetime because of the prolonged exposure to harsh environmental conditions such as high operating temperature, high humidity etc. A long-lifetime multi-channel LED driver consisting of front-end AC-DC boost power factor correction (PFC) converter followed by a DC-DC power conversion stage with dimming capability for LED-based street light is proposed in this study. This LED driver uses an inductor-based auxiliary decoupling circuit at the output of the AC-DC converter for mitigating the double-line-frequency power ripple present in the DC bus. The inductive ripple power storage circuit has a longer lifetime than a conventional capacitive storage circuit which is usually implemented by electrolytic capacitors. A digital control method is proposed to realise the decoupling control along with PFC control by a single non-digital signal processor micro-controller ST STM32F103RBT6. The proposed LED driver for street lighting is analysed and validated on a 150 W test setup. A comparison of active decoupling AC- DC converters for eliminating secondary-harmonic power ripple is displayed.