Small-Signal Model and Controller Design of Interleaved Isolated Boost Converter for PV Application

The interleaved isolated boost converter (IIBC) with voltage-doubler provides voltage boosting, galvanic isolation, and low risk of transformer saturation issue in case of mismatched gate signals. These good features make the IIBC a good candidate as a first stage in microinverter architectures, where the photovoltaic (PV) module voltage needs to be boosted up at the input of a second stage dc-ac inverter. Although the topology is well-known, no research has been conducted on the dynamics and the closed-loop control of this converter. This paper presents the small-signal model and a control system design in the specific case of photovoltaics. Step-by-step small-signal modeling is reported, as well as the design of a finite dc-gain controller, which is discussed in detail. Both the open-loop control-to-output analytical model and the closed-loop results including the PV source have been validated with simulations.