A BIFRED converter with a wide load range

In this paper, the boost integrated flyback rectifier energy DC-DC (BIFRED) power converter which incorporates power factor correction, output voltage hold-up and input-to-output isolation is examined. The particular problem of high bulk capacitor voltage at light loads is addressed and it is shown how this may be resolved if the boost and flyback sections of the power converter are allowed to operate discontinuously. The criteria for ensuring correct operation in the discontinuous mode are investigated. It is shown that operating in this mode places no restrictions on the minimum load and simplifies the control loop design. >