Analysis, control, and modeling of the three-port converter without port voltage constraint for photovoltaic/battery system application

For a photovoltaic (PV)/battery power system consisting of PV module, energy storage system, and local load, using a three-port converter (TPC) instead of several single-input converters is more desirable, such as simpler circuit, higher efficiency, lower cost, and centralized control without communication circuit. In this paper, a TPC is proposed and analyzed, which includes operating modes, steady-state performance, and parameter design. Compared with other converters, the proposed TPC has a low cost, compact structure, and a more flexible voltage relationship among all ports. Moreover, energy management and control methods are further proposed for PV/battery systems based on the proposed converter, which can achieve maximum power point tracking (MPPT) of PV module and constant output voltage. In order to design the control loop and realize multivariable optimal control, a small-signal model of the converter is obtained in each operation mode. Then a detailed decoupling design approach based on a small-signal model is provided to allow a separate controller design for the proposed converter. Finally, the validity of the proposed converter and its energy management and control method are verified by experimental results.

Automated summary

This paper introduces a three-port converter (TPC) and its application in energy management and control methods for a PV/battery system, achieving lower costs, compact structure, and more flexible voltage relationships between ports.