Three-Port Flyback Converter for Photovoltaic Module Integration in Bipolar DC Microgrids

摘要

The focus is on bipolar dc microgrids with distributed photovoltaic energy generation. Flyback converter with two outputs is used as a photovoltaic module-level interface into the bipolar dc microgrid of much higher voltage. Sigma-delta modulation is proposed to enable one of the converter outputs for balancing the bipolar dc microgrid naturally. This modulation is synchronous with PWM of the input side power switch that is controlled with duty cycle duration calculated by a maximum power point tracking algorithm. As a result, no PI controllers are required in the proposed control system and, thus, stability is ensured. The proposed concept is verified through numerical simulations in PSIM 11 software.