US 12,445,060 B2
Positive and negative bipolar modular multilevel alternating current-alternating current frequency converter
Fujin Deng, Jiangsu (CN); and Haoran Yi, Jiangsu (CN)
Assigned to SOUTHEAST UNIVERSITY, Nanjing (CN)
Filed by SOUTHEAST UNIVERSITY, Jiangsu (CN)
Filed on May 31, 2025, as Appl. No. 19/224,792.
Application 19/224,792 is a continuation of application No. PCT/CN2024/079922, filed on Mar. 4, 2024.
Claims priority of application No. 202310214857.2 (CN), filed on Mar. 8, 2023.
Prior Publication US 2025/0293611 A1, Sep. 18, 2025
Int. Cl. H02M 5/16 (2006.01); H02M 5/297 (2006.01)
CPC H02M 5/16 (2013.01) [H02M 5/297 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A positive and negative bipolar modular multilevel alternating current (AC)-AC frequency converter, comprising a modular multilevel frequency converter and a three-phase three-winding bipolar transformer, wherein
the modular multilevel frequency converter has an ABC three-phase structure, a power frequency side is connected to a power frequency power grid, and a low frequency side is connected to a low frequency power grid through the three-phase three-winding bipolar transformer;
the three-phase three-winding bipolar transformer comprises two Y-connected secondary transformers T1 and T2, T1 is a positive transformer, and T2 is a negative transformer; and three-phase ports of the Y-connected secondary transformer T1 are connected to upper ends of three-phase upper bridge arms of the modular multilevel frequency converter, and three-phase ports of the Y-connected secondary transformer T2 are connected to lower ends of three-phase lower bridge arms of the modular multilevel frequency converter; and
in the three-phase three-winding bipolar transformer, a neutral point o of T1 and a neutral point o′ of T2 are connected with each other, a voltage relationship between T1 and T2 transformer ports is that a phase difference between X and x ports is 180°, a phase difference between Y and y ports is 180°, and a phase difference between Z and z ports is 180°.