Capacitor voltage balancing with online controller performance-based tuning for a switch-sharing-based multilevel inverter
Document Type
Article
Publication Date
5-1-2021
Abstract
Switch-sharing-based multilevel inverters offer great advantages in terms of efficiency improvement and output quality enhancement for low-power photovoltaic (PV) applications. However, the capacitor voltage balancing issue may critically deteriorate the output voltages, and thus could nullify the aforementioned benefits. Hence, this paper proposes a capacitor voltage balancing solution based on a buck-boost converter with performance-based tuning controllers to address the issue. The proposed controllers are designed based on the proportional-integral (PI) configuration equipped with an online tuning mechanism. The main purpose of the online tuning mechanism is to fine tune the proportional gain according to the DC input voltage, based on the measured output current total harmonic distortion (THD) performance of the inverter, while at the same time preventing the controller from reaching a state of saturation. By using the actual measurement of current THD performance, online tuning accuracy can be improved since no ideal condition is assumed, and thus, the associated error can be minimized. Simulation and experimental results reveal that the capacitor voltages can be balanced at high modulation indexes with improved current harmonic performance able to be be acquired at the inverter's output.
Keywords
Buck-boost converter, Capacitor voltage balancing, Online tuning, Switch-sharing-based multilevel inverter
Divisions
umpedac
Publication Title
Applied Sciences
Volume
11
Issue
10
Publisher
MDPI
Publisher Location
ST ALBAN-ANLAGE 66, CH-4052 BASEL, SWITZERLAND