Solar PV Energy System Based on Series Interleaved Three-Level Boost Converter and Five-Level MLC2 Inverter

This paper presents the design and analysis of a standalone power electronic system for converting solar photovoltaic (PV) energy to feed three-phase AC loads at 60 Hz standard voltage. The system consists of a front-end series interleaved three-level boost (ITLB) DC-DC converter fed by two PV arrays and connected to the dc bus of a three-phase five-level multilevel-clamped multilevel converter (MLC
²
). Each PV array is also connected to a buck-boost converter that functions as energy flow regulator to a battery pack or some other type of load, and also keeps the total inverter dc bus constant. The series ITLB converter is used for maximum power point tracking (MPPT) and dc bus voltages balance. The MLC
²
inverter is built up by switch legs of three-level neutral-point clamped (NPC) type. Two MPPT algorithms, Perturb and Observe (P &O) and Beta method, were implemented in C language. Digital simulations with PSIM software were performed in order to evaluate the performance of the energy conversion system under each combination of MPPT method and control switching technique. While solar irradiation is varied, capacitor voltages balance, voltage ripple and inductor currents are assessed. The potentiality of the proposed energy conversion system is evaluated for off-grid applications.