A Cascaded Interleaved Bootstrapped Gate Driver Power Supply for Multilevel Photovoltaic Inverters

In addition to high conversion efficiency, low cost and compact size are also desirable for the wide-scale adoption of multilevel Photovoltaic (PV) inverters. Generally, the multilevel PV inverters employ a large number of power semiconductor devices, most of which are not ground referenced. The cost and size of PV inverters is expected to increase due to isolated power supplies for gate drivers of high side devices. A Bootstrapped gate driver supply eliminates the need for isolated power supplies by introducing relatively low cost and low size components, such as resistors, diodes, and capacitors. This paper proposes a methodology to design a bootstrapped gate driver power supply for multilevel PV inverters. The proposed approach is generic and applicable to a wide range of popularly known multilevel inverter topologies. The design guidelines and component sizing constraints for the proposed methodology are also presented. The proposed approach is also demonstrated for a single phase transformerless multilevel PV inverter. Its operation is validated by experimental studies.