Ripple free operation of two-stage boost type DC-DC converter

In this paper, the ripple free operating method of two-stage boost type dc-dc converter is proposed which is suitable for PV and fuel cell systems. The ripple free two-stage boost type dc-dc converter (RFTSBC) is composed of a conventional interleaved boost converter and a cascade boost type chopper. The primary stage is driven at a fixed duty ratio to make the input current ripple of the RFTSBC close to zero. The second stage moreover boosts the voltage, and controls the output voltage. In addition, the two inductors in the primary stage can be miniaturized within continuous current mode (CCM) by adjusting the switching frequency. As a result, the equivalent series resistance (ESR) of the inductors in the primary stage can be reduced. The operation of the RFTSBC has been confirmed by reduced scale circuit experiment.