Efficiency Improvement Study on an Isolated Modular Boost Converter in Low Output Operation

Abstract

An isolated modular boost converter is proposed as one of the solutions to efficiently deliver power from low voltage renewable energy sources such as photovoltaic cells to a high voltage battery. The converter consists of multiple boost modules, each of which comprises a phase shifted full bridge converter, a transformer and a diode rectifier. Both high boost ratio and high efficiency are achieved by connecting the output of the boost modules in series. The fundamental characteristics of the converter are demonstrated. In addition, parallel boost modules operation with imbalanced output power is proposed for further efficiency improvement. It is experimentally confirmed that the proposed power unbalancing scheme between two parallel boost modules improves the efficiency over wide operating ranges without any drawbacks.