Soft switching boost converter for DC input LED drivers

LED lighting has attained maximum acceptance in the recent past for indoor, outdoor and special purpose applications. In most of the battery driven / PV based applications, efficient constant current driving of LED arrays is essential. Therefore, adopting soft switching for the power switch is important to achieve greater efficiency at higher frequencies, simultaneously realizing better power densities. In this paper, a technique is proposed which results in the complete soft switching of the power switch without any auxiliary switch and /or elaborate control mechanisms. Only an additional transformer is introduced to recycle the switching power to the output load. The concept is validated by building a 100W LED driver with 24 VDC input and 135 VDC output operating at 110 KHz. About 6 percent improvement in the efficiency was achieved with this technique.