A Five-Level NPC Photovoltaic Inverter with an Actively Balanced Capacitive Voltage Divider

A new five-level photovoltaic Inverter is presented, implemented by associating a Multistage Stacked Boost Architecture (MSBA) with a 5-level NPC inverter. Ahead of the MSBA conversion stage, a conventional boost converter allows the operation of the PV cells with a variable voltage using a maximum power point tracking strategy (MPPT). The paper describes a robust voltage balancing principle for the MSBA-stage, which includes local feed-forward for the current control references of each balancing modules. The feed-forward signals are estimated from the inverter output current, with the help of the switching signals of the 5-level inverter. Simulation results are presented, as well as first experimental results.