Abstract
The modular multilevel converter (MMC) containing full-bridge submodules (FBSMs) can increase the modulation index to reduce the energy storage requirement. The MMCs containing FBSMs can also adjust the dc voltage to fit special applications. However, limited research explores the energy storage characteristics of MMCs with variable dc voltages, and few effective approaches can ensure low-energy storage requirements. This study proposes an approximate analysis method for the energy storage requirement in MMC with variable dc voltages. Results reveal that the energy variation under low dc voltages restricts the reduction effects of the increased modulation index on the energy storage requirement. Then, on the basis of the fact that the low ac component of the arm current under low dc voltages provides a large current margin, an optimal circulating current (OCC) is proposed to optimize the energy variation under low dc voltages. In addition, a practical curve-fitting approach is proposed to facilitate the calculation of OCC in real-time controllers. With these approaches, the energy storage requirement with variable dc voltage becomes similar to that with constant rated dc voltage. Simulation and experimental results verify the analysis.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
