Recently, it has been shown that complementarity models are an attracting tool for representing power converters in both open- and closed-loop configuration. A unique dynamical complementarity model captures all the modes of a power converter, without assuming the a priori knowledge of the sequence of modes or of the switching time instants. In this paper, we derive the complementarity model of a single-phase active filter with cascaded multilevel inverter. A combination of the unipolar and the phase-disposition PWM techniques is used with the goal of regulating the dc-link voltage. As benchmark for comparison, the time evolution of inductors currents and capacitors voltages computed with the complementarity procedure is compared with the ones obtained with PSIM software.