Modular Single-Stage Three-Phase Flyback Differential Inverter for Medium/High-Power Grid Integrated Applications

Area of Science:

• Electrical Engineering
• Renewable Energy Systems
• Power Electronics

Background:

• Grid-integrated solar photovoltaic (PV) systems require efficient and reliable power conversion.
• Existing inverters often involve multiple stages, increasing complexity and reducing efficiency.
• Medium/high power applications demand robust solutions with features like galvanic isolation and modularity.

Purpose of the Study:

• To propose and analyze a single-stage three-phase modular flyback differential inverter (MFBDI) for solar PV grid integration.
• To develop a mathematical model for the MFBDI considering time-varying duty cycle and frequency variations.
• To investigate harmonic compensation strategies for improved grid current quality.

Main Methods:

• Development of a novel single-stage three-phase modular flyback differential inverter (MFBDI) structure.
• Mathematical modeling and analysis of the MFBDI with time-varying duty cycle and frequency.
• Implementation of a low-pass filter (LPF)-based harmonic compensation strategy for second-order harmonic components (SOHC).
• Simulation (PSIM/Simulink) and experimental validation of the MFBDI with parallel flyback modules and SiC MOSFETs.

Main Results:

• The MFBDI demonstrates reduced component count, single-stage power processing, and high power density.
• Grid current Total Harmonic Distortion (THD) was reduced from 36% to 4.6% by mitigating SOHC from 51% to 0.8%.
• The SOHC compensation technique effectively eliminated third-order harmonic components from the DC input current.
• Modular operation was confirmed under a 15% parameter mismatch between flyback modules.
• SiC MOSFETs reduced switching losses at high frequencies.

Conclusions:

• The proposed MFBDI is a viable solution for medium/high power solar PV grid-integrated applications.
• The developed harmonic compensation strategy significantly improves grid current quality.
• The modular design offers flexibility, scalability, and improved reliability for renewable energy systems.