An Electromagnetically Integrated LCL-EMI Filter for V2G Power Converters: Topology, Analysis, and Implementation

Abstract

High-frequency grid-tied inverters in vehicle-to-grid (V2G) systems often produce lots of high-frequency harmonics and electromagnetic interference (EMI) noise. Therefore, a filtering module, which consists of a harmonic filter and an additional EMI choke, is typically required to effectively restrain the aforementioned noises, but this passive module will inevitably raise size and cost of the converter, which goes against high-power density demand of electric vehicles (EVs). To address this issue without impairing the filter’s performance, this article proposes a decoupled electromagnetically integrated structure of a symmetrical LCL-EMI filter for grid-tied converters in V2G applications. EE-shape magnetic core and flexible multilayer foil (FMLF) technique are employed in the integration design, the FMLF windings for achieving a symmetrical LCL filter are wound on side limbs of the EE core, and the EMI choke windings are arranged on the central limb. The used proper terminal configuration of the windings can almost realize function-decoupling between the LCL unit and EMI choke. Moreover, magnetic decoupling can be achieved between converter- and grid-side inductors of the LCL unit through air-gap design in the EE core’s side limbs, which can preserve the LCL unit’s satisfactory harmonic attenuation performance. Performance analysis and design principles of the integrated module are introduced, and the experimental results from a 1-kW SiC-MOSFET high-frequency grid-tied converter confirm the feasibility and validity of the approach.