PROJECT TITLE :

Discrete-Time Sliding-Mode Observer for Capacitor Voltage Control in Modular Multilevel Converters - 2017

ABSTRACT:

This paper proposes a discrete-time sliding-mode observer (SMO) for equivalent capacitor voltages control in modular multilevel converters, aiming to scale back the Communication complexity in applications with many series-connected submodules. The observed voltages of the equivalent capacitors are utilized in the voltage control loops, resulting in a less complicated implementation, that demands low communication effort, since the individual capacitor voltages don't seem to be used in the central processor. The proposed SMO was obtained from discrete-time analysis with a stability improvement, differently from discretized observers previously proposed in the literature. A discrete-time methodology is presented to design the observer and guarantee the proper operation of the Control System. The proposed SMO style methodology in the discrete-time domain enables a simple design of the observer, guaranteeing transient and steady-state observer performances. Simulation results are presented to demonstrate an example of the proposed methodology, where the observer operates with the management system beneath distinct conditions. Additionally, experimental results are included to demonstrate the effectiveness of the proposed control system with discrete-time SMO for the equivalent capacitor voltages.