Working Principle, Simulation and Measurement Results of a Novel Hybrid Cascaded H-Bridge Inverter for STATCOM and AHF Purposes

Abstract:
The change to a decentralized grid due to the fast growth in renewable energy systems and the increasing number of non-linear loads like electrical vehicle chargers, bring new challenges to maintain a high grid quality. A former gap in the standardization of harmonic emissions in the frequency range between 2kHz and 150kHz led to a shift of modern inverters into this range. This trend is intensified by newer power transistors with better switching characteristics. Today common active filter topologies are two- or three-level inverters, which can’t compensate harmonics in this frequency range. Their dynamic behavior is limited by the maximum switching frequency of the required power switches with high blocking voltage. Therefore there is a need for new, high-dynamic and cost-effective active filter topologies. This paper proposes such a new topology based on a hybrid cascaded H-bridge. The basic function principle, its benefits and limitations are explained. The function principle of the topology is verified with simulation and measurements on a demonstrator.