Comparative study of half-bridge LCC and LLC resonant DC-DC converters for ultra-wide output power range applications

The Half-Bridge (HB) LCC resonant DC-DC converter and HB LLC resonant DC-DC converter circuit are comparatively studied for high efficiency ultra-wide output power range application in this paper. The output voltage ranges from minimum output voltage to twice that value. And the output current ranges from 10% load to 100% load. So the output power spans over a wide range, from minimum to 20 times that. The detailed resonant tank characteristics analysis for HB LCC and LLC resonant converter is provided. Through the 150W hard prototype experiments validation, it is shown that HB LLC resonant DC-DC converter can achieve better performance with flat efficiency, narrow switching frequency range compared with HB LCC resonant DC-DC converter for wide output current application at both 75V & 150V output voltage from 10% output current to 100 % output current conditions. HB LLC resonant DC-DC converter is more preferred power conversion circuit topology to achieve high performance with flat efficiency, narrow switching frequency range in ultra-wide output power range applications.