A novel switched-capacitor multilevel inverter offering modularity in design

A new topology of switched-capacitor (SC) multilevel inverter (MLI) which enables modular design is presented in this paper. By employing the series-parallel SC technique, the proposed MLI provides voltage step-up capability and self-balancing of the capacitor voltage. Since the maximum voltage stress of the capacitors and the switches is limited by the proposed topology and independent of the number of output voltage levels, the SCMLI can be modularized with low-voltage SC units to form a scalable inverter with substantial decrease in production cost. In this paper, the key features and operation principle of the proposed topology are described. The capacitor voltage ripples and the associated energy loss of the SCMLI with staircase modulation under different loading conditions and operating frequencies are analyzed and the consideration for component sizing is discussed. The operation of the proposed topology is verified by the simulation and experiment on a 9-level SCMLI with three SC units.