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

With the significant development in the manufacturing process of LEDs, LEDs are promising for various lighting applications. In order to achieve better performance and higher reliability, the multiple LED strings structure is adopted in many applications, such as street lighting and tunnel lighting. This paper is aimed to describe a multi-channel constant current LED driver which is composed of a master AC source and some slave passive constant current sources according to the number of LED strings. The high frequency resonant inverter is controlled to operate as the master AC source, whose output forms the high frequency AC bus, each LED string is individually powered by its corresponding salve passive constant current source driven by the high frequency AC bus. By employing the LED´s u-i model instead of the constant resistive load, the performance and characteristics of the driver are analyzed in detail and the experimental results are provided to verify the concept.