Comparison and evaluation of different three-level inverter topologies for PV systems

Abstract

In this work different three-level topologies suitable for PV systems are analyzed. First the basic operation principles of the Neutral Point Clamped (NPC), Active Neutral Point Clamped (ANPC) and Mixed Voltage Neutral Point Clamped (MNPC) topologies are explained and the used PWM strategies are presented. All three topologies are realized in hardware on a modular test setup, so that it is possible to operate them under the same conditions. Efficiency measurements under different conditions (switching frequency fPWM = {16; 48; 90} kHz, output power, silicon carbide (SiC) semiconductors, driving circuits) are shown. Exceptional efficiencies of η16kHz = 99.1 % and η90kHz = 98.6 % are obtained.