Design Methodology for a Medium Voltage Single Stage LLC Resonant Solar PV Inverter

TL;DR

This paper presents a design methodology for a medium voltage single-stage LLC resonant inverter for solar PV systems, emphasizing reduced switching losses and validated through MATLAB/Simulink simulations.

Contribution

It introduces a novel design procedure for LLC resonant converters tailored for high-power medium voltage grid-tied PV inverters, focusing on loss reduction and filter optimization.

Findings

Resonant converter achieves ZVS, reducing switching losses.

Simulation results confirm THD compliance and effective filtering.

Design adaptable to various load and input voltage conditions.

Abstract

An inverter is generally employed with MV LFT to connect to the grid in a grid-tied PV system. However, in some single-stage topologies, the LFTs are replaced by HFT combined with an unfolder inverter. Generally, these topologies have limited use at high-power MV grids due to high switching losses on the primary side. This study proposes an LLC resonant converter-based single-stage inverter design procedure. Resonant converters make use of ZVS to reduce switching losses. The design includes both the resonant tank as well as output filter components. The design is verified by simulations in MATLAB/Simulink for various loads and input voltages at 13.8kV grid output voltage. THD simulations validate the filter design.