Analysis of cross-connected half-bridges multilevel inverter for statcom application

Abstract

This paper suggested a single-phase cross-connected half-bridges multilevel inverter (CCHB-MLI) topology for static synchronous compensator (STATCOM) applications. The proposed MLI structure consists of cross-connected multilevel cells connected in series with a more optimized number of devices to synthesize a higher number of voltage steps. Each cell in the structure consists of a set of switches and a DC-capacitor. Typically, when several DC-capacitors are used in an inverter, the DC voltages fluctuation occurs due to tolerance between passive element and asymmetric switch losses. A dual-loop control technique has been proposed with level-shifted pulse width modulation PWM to overcome these issues. The proposed methodology balances the DC-voltages using a proportional-integral controller by adjusting the switch duty cycle. The control method helps offset the issue of aggravated fluctuation while preserving the delivered reactive power distributed equally among the DC-capacitors at the same time. A thorough comparison is made between the proposed inverter concerning the number of components and efficiency to demonstrate the effectiveness of previous topologies. Moreover, a simulation model built in simulink and experimental results take from laboratory prototype to confirm the effectiveness of proposed structure and its control technique.