| Multiport Power Electronic Interface (MPEI) which links the distributable power sources with its necessary storage units, acts as the active power node within the DC microgrid, therefore is able to realize the systematic control and synthesized management of generating, storing and consuming process. Based on the DC microgrid system linking the photovoltaic (PV) sources, energy storage units and terminal loads together, this research focuses on the MPEI with Buck-Boost cell and presents the fundamental control system strategy and power management scheme.Firstly, topology of elemental power cell which constitutes the MPEI is proposed and the PWM mode of MPEI is analyzed. Furthermore, based on the characteristics of the DC microgrid, satisfactory mathematical model of the MPEI is deduced from different operation modes using state space averaging method and small signal analysis. On the other hand, characteristics of PV port are provided and therefore the Maximum Power Point Tracking (MPPT) scheme is introduced. Circuit parameters of MPEI and features of the control target are proposed. Apart from this, the specification of bus voltage control is analyzed and control strategy is designed. A MPEI control system is designed which is able to connect one PV, two storage units and microgrid bus. In order to distribute power flow first-handedly and efficiently, active distributive factor is conceived and integrated into the control algorithm. Control system design and circuit operation are verified by MATLAB/SIMULINK model-based simulation and Simulink-PLECS circuit-based simulation respectively.Prototype of MPEI is made and the validity of system is proven by experimental results. Moreover, bus voltage control strategy and transient energy management scheme are also tested. |
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