Input-output feedback linearization control of a Cascaded H-bridge multilevel inverter

This paper proposes a voltage controller for Cascaded H-bridge three-phase multilevel inverters operating in islanded mode with constant-amplitude constant-frequency output voltages. For this purpose, a non linear state-space model of the converter feeding a three-phase load via a second order LC filter is developed. Next, an input-output feedback linearization controller is designed so as to drive the output voltages to track the target references. Numerical simulations carried out on a 7 level inverter emphasize the effectiveness of the proposed model and control law. Based on feedback linearization strategy, the closed loop response of the system is stable even in case of disturbances. The transient state is extremely short and presents small overshoots.