Compact Wind Energy Conversion System Using a Passive Diode-Bridge Rectifier Without Filter in the Dc-Link

A passive three-phase diode-bridge rectifier, though simple and reliable, generates high harmonics and has an unregulated dc-link voltage. Typically, bulky LC filters and dc/dc boost converters are used to mitigate these issues, which increases system size and complexity. This paper proposes a compact wind energy conversion system (WECS) using a passive rectifier on the generator side, integrated with a grid-connected Full-Bridge Modular Multilevel Converter (FBMMC). The FBMMC can naturally provide boost capability and by optimizing the FBMMC's internal control, it can serve as an active dc filter, injecting compensating currents to reduce harmonics and smooth dc-link and generator phase currents. This eliminates the need for traditional bulky LC filters, resulting in a more efficient and compact WECS. The proposed strategy's effectiveness is validated through experimental testing, showcasing its potential to replace conventional hardware components in the dc-link with a software-based solution for improved performance and reduced system size, and complexity.