Comparative Evaluation of Individual and Coupled Inductor Arrangements for Input Filters of PV Inverter Systems

Photovoltaic systems (PV) of higher power are connected to the grid through three-phase inverters via output filters which are designed to limit Electromagnetic Interference (EMI), in order to comply with international standards. With the purpose of reducing the volume of this converter, this paper evaluates 3 configurations of bridge legs and output magnetic components and identifies the most compact options for a system of 10kVA. A single bridge leg and two interleaved bridge legs with coupled or uncoupled inductors are considered in the comparison. Switching frequency and total silicon area are fixed and the volume of the passive components and the heatsink are evaluated as well as the system efficiency. The analysis developed in this paper show that the configuration with interleaved bridge legs and coupled inductors has a total volume close to 70% when compared to the configuration with interleaved bridge legs and uncoupled inductors, but it has a similar total volume when compared to the configuration with a single bridge leg. Although it is reported in the literature that systems with coupled inductors usually have a lower volume, the case at hand has the output filters designed to comply with EMI standards and it will be shown that, like this, the volume reduction of magnetic components provided by coupled inductors is compensated by the increase on the volume of capacitors.