Controller Design for a Dc-microgrid Pv Converter Based on Asymmetrical Γ-source Inverter Considering the Sun Tracker Operation

This paper presents a power electronic interface (PEI) converter with three ports to connect a Photovoltaic system and a DC-microgrid to the main grid. The proposed converter is based on asymmetric Γ-source inverter, which makes two controllable ports in its DC side without utilizing any excessive DC/DC converters, which make it interesting for multi-port applications. The PEI system is expected to regulate DC-microgrid voltage to its reference voltage while keeping PV voltage to its reference value provided by maximum power point tracking (MPPT) algorithm in a certain direction of the PV panel determined by sun tracker controller (STC). For avoiding interference between STC system and MPPT algorithm, the PV voltage controller is designed much faster than STC, therefore until the next updating of the PV panel direction, the PV voltage controller can change PV voltage in some steps to find maximum power point. To this aim, the dynamic model of the PEI system is obtained using average state model and the appropriate control system is designed based on dynamic model of the system. According to the two degree of freedom in asymmetric Γ-source inverter pulse width modulation composed of inverter modulation index and inverter shoot through duty cycle, the control system are able to control DC-microgrid and PV voltage independently. The inverter shoot through duty cycle is used to control the PV voltage while the inverter modulation index, which is generated in AC current controller, is utilized for regulating the DC-microgrid voltage. The performance of the proposed control system for creating a DC-microgrid PV system is evaluated using simulation in MATLAB/Simulink.