ADRC Control of Cascaded H-Bridge Multilevel DC/AC Converters

Multilevel inverters have gained popularity in recent years for high power applications thanks to their better harmonic profile and higher power ratings. In this paper a Cascade H-Bridge Multilevel Inverter (CHMI) is presented to generate seven voltage levels to create sinusoidal voltages with extremely minimal harmonic distortion for use in an Uninterruptible Power Supply (UPS) system. The (CHMI) is controlled using two types of regulators. A first one based to the nonlinear backstepping approach and a second one based the active disturbance rejection control (ADRC), which is a new approach who operates by continuously estimating the disturbance signal in order to compensate for it effectively. The numerical simulation results obtained using Matlab/ Simulink prove that the (ADRC) strategy offers better performance compared to backstepping control in terms of stability, accuracy, and robustness.