A comprehensive analysis and closed-loop control of a non-isolated boost three-port converter for stand-alone PV system

Abstract

This study critically investigates analysis and control of non-isolated boost three-port DC to DC converter (TPC) for standalone PV system. The converter is controlled such that regulates flow of power from PV array to load and batteries as storage devices. According to PV power, there are four operating modes of operation of converter. Simple reduced-order dynamic models of the converter in various modes of operation are obtained using state-space averaging and small-signal techniques. In this work, the controllers of the closed-loop scheme are designed and only two controllers are used to achieve output voltage regulation, and to extract maximum power from PV array under different operating conditions. Closed-loop system simulation is studied to verify the operation of converter with the designed controllers in different modes. Transition between modes is presented with solar radiation variation and change of connected loads. Experimental verification of control systems at different modes of operation is investigated. The experimental results show that the controllers can regulate the power flow between TPC three ports and regulate output voltage under PV irradiance variation and load changing. The controller shows good performance measures such as maximum settling time of 0.06 s, maximum steady-state ripples of ±0.8 %, and 99.3 % power efficiency.

Keywords

• State-space model
• Closed-loop control
• Stability
• Maximum power extraction
• Photovoltaic system