Year
2024
Degree Name
Master of Philosophy
Department
School of Electrical, Computer and Telecommunications Engineering
Abstract
Magnetic linked converters play a significant role in the power electronics industry due to their high degree of control flexibility, energy-efficient power routing, galvanic isolation property, and modular functionality. A magnetic linked converter can be developed based on different topologies to suit various applications, such as an effective interface for renewable energy integration to the traditional power grid, more electric aircraft, electric vehicle charging implementation, etc. The basic principle of operating a magnetic linked converter is to control the phase angle difference of the modulating signals, which generate switching actions to drive the converter. Controlling the phase angle controls power transmission and power flow direction in the magnetic linked converter. Traditionally, the shifting of the phase angle can be controlled by different linear control techniques, like proportionalintegral (PI) control, disturbance feedforward control, and virtual direct power control. They commonly suffer from high voltage overshoot and undershoot under abrupt load change. Moreover, the controllers cannot ensure smooth bidirectional power routing and a high level of decoupling, which initiates unwanted control interactions. In the worst-case scenario, the controllers can be fully saturated and cause severe system-wide unbalancing issues.
In this research, the configuration of the multiport magnetic linked converter (MMLC) is adopted for the electric vehicle charging application. Compared with the traditional dual-port magnetic linked converter (DMLC), the MMLC provides higher degrees of control flexibility to supply multiple loads simultaneously while retaining the advantages of the DMLC in terms of soft-switching ability, galvanic isolation, and high-density power routing. An effective bidirectional power controller with a unique decoupled control mechanism is implemented to deal with the cross-coupling characteristics of the MMLC. Regarding the control method, an advanced non-linear model predictive controller (MPC) is proposed for the MMLC to ensure robust voltage control, smooth bidirectional power routing, and high degrees of decoupling to avoid any control interactions. The proposed controller facilitates robust and effective operation of the MMLC, where the voltages at the multiple ports can be perfectly balanced under rapid load change conditions so that the ports can be accessed in a plug-n-play manner. The performance of the controller is tested under different load change conditions at different ports of the MMLC at random time intervals in terms of dynamic response, voltage overshoot and undershoot, smooth bidirectional power handling capability, and decoupling range.
Recommended Citation
Qi, Zhipeng, Advanced Control Technique for Multiport Magnetic Linked Converters, Master of Philosophy thesis, School of Electrical, Computer and Telecommunications Engineering, University of Wollongong, 2024. https://ro.uow.edu.au/theses1/1838
FoR codes (2008)
0906 ELECTRICAL AND ELECTRONIC ENGINEERING
Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.