Dimmable LED Assembly Driven by Passive LED Driver for Smart Lampposts

A light-emitting diode (LED) system comprises an LED driver and an LED assembly in which the LED modules are connected and mounted on the heatsink. Traditionally, the dimming function is provided by the LED driver. This paper presents a dimmable LED assembly so that even LED systems driven by non-dimmable LED drivers can become dimmable easily. The new concept can be applied to smart lampposts driven by non-dimmable passive LED drivers because the new dimmable LED assembly can be connected to smart controller mounted on the same lamppost. In the dimmable LED assembly, bypass switches can be used to selectively cut off power from some groups of LED modules for dimming purpose. The new dimming mechanism has been practically verified in a 110 W passive LED system, which achieves an input power factor above 0.9 and more than 88% efficiency across a wide dimming range.