A novel single-phase voltage sag restorer with diode-clamped multilevel bridge

Abstract

A novel single-phase voltage sag restorer with diode-clamped multilevel bridge is presented. In the proposed circuit, traditional two-level half bridge inverter is replaced by multilevel diode-clamped inverter, in which the dc-bus voltage is split into several levels by series-connected bulk capacitors. Although the multilevel circuit has more component count than the two-level circuit it is more suitable for high voltage applications. The restorer is bypassed under normal operating conditions and is connected to the load depending upon voltage sag detection. The switches of the inverter are controlled by PWM signals. In the paper the operation of the multilevel circuit is simulated in SABER to study the operating capability of the multilevel inverter. A comparative study between the traditional two-level circuit and the proposed multilevel circuit is provided to highlight the performance of the multilevel circuit.