Provided are voltage and frequency transformation systems, methods and devices, and relate to the field of transformers. The method includes: inputting low-frequency electric energy with frequency lower than a first predetermined frequency threshold; the low-frequency electric energy including low-frequency and low-voltage electric energy or low-frequency and high-voltage electric energy; obtaining high-frequency electric energy with frequency higher than a second predetermined frequency threshold; the high-frequency electric energy including first high-frequency and low-voltage electric energy or first high-frequency and high-voltage electric energy; obtaining second high-frequency electric energy after voltage transformation; the second high-frequency electric energy including second high-frequency and high-voltage electric energy or second high-frequency and low-voltage electric energy; obtaining second low-frequency electric energy; the second low-frequency electric energy including second low-frequency and high-voltage electric energy or second low-frequency and low-voltage electric energy.

The present disclosure provides a positive and negative bipolar modular multilevel alternating current (AC)-AC frequency converter, including a modular multilevel frequency converter and a three-phase three-winding bipolar transformer. The modular multilevel frequency converter has an ABC three-phase structure, each phase includes the same upper bridge arm and lower bridge arm, and the upper and lower bridge arms include n full-bridge sub-modules (FBSMs) and a bridge arm inductor connected in series. The positive and negative bipolar modular multilevel AC-AC frequency converter can be further expanded and enable bidirectional energy flow. In the present disclosure, by introducing a positive and negative bipolar three-winding transformer, an AC-AC frequency converter topology with simple structure, high efficiency, flexibility and reliability is realized, which has high practical value.

The present disclosure provides a positive and negative bipolar modular multilevel alternating current (AC)-AC frequency converter, including a modular multilevel frequency converter and a three-phase three-winding bipolar transformer. The modular multilevel frequency converter has an ABC three-phase structure, each phase includes the same upper bridge arm and lower bridge arm, and the upper and lower bridge arms include n full-bridge sub-modules (FBSMs) and a bridge arm inductor connected in series. The positive and negative bipolar modular multilevel AC-AC frequency converter can be further expanded and enable bidirectional energy flow. In the present disclosure, by introducing a positive and negative bipolar three-winding transformer, an AC-AC frequency converter topology with simple structure, high efficiency, flexibility and reliability is realized, which has high practical value.

The present disclosure provides a positive and negative bipolar modular multilevel alternating current (AC)-AC frequency converter, including a modular multilevel frequency converter and a three-phase three-winding bipolar transformer. The modular multilevel frequency converter has an ABC three-phase structure, each phase includes the same upper bridge arm and lower bridge arm, and the upper and lower bridge arms include n full-bridge sub-modules (FBSMs) and a bridge arm inductor connected in series. The positive and negative bipolar modular multilevel AC-AC frequency converter can be further expanded and enable bidirectional energy flow. In the present disclosure, by introducing a positive and negative bipolar three-winding transformer, an AC-AC frequency converter topology with simple structure, high efficiency, flexibility and reliability is realized, which has high practical value.

The present disclosure provides a positive and negative bipolar modular multilevel alternating current (AC)-AC frequency converter, including a modular multilevel frequency converter and a three-phase three-winding bipolar transformer. The modular multilevel frequency converter has an ABC three-phase structure, each phase includes the same upper bridge arm and lower bridge arm, and the upper and lower bridge arms include n full-bridge sub-modules (FBSMs) and a bridge arm inductor connected in series. The positive and negative bipolar modular multilevel AC-AC frequency converter can be further expanded and enable bidirectional energy flow. In the present disclosure, by introducing a positive and negative bipolar three-winding transformer, an AC-AC frequency converter topology with simple structure, high efficiency, flexibility and reliability is realized, which has high practical value.

Provided are voltage and frequency transformation systems, methods and devices, and relate to the field of transformers. The method includes: inputting low-frequency electric energy with frequency lower than a first predetermined frequency threshold; the low-frequency electric energy including low-frequency and low-voltage electric energy or low-frequency and high-voltage electric energy; obtaining high-frequency electric energy with frequency higher than a second predetermined frequency threshold; the high-frequency electric energy including first high-frequency and low-voltage electric energy or first high-frequency and high-voltage electric energy; obtaining second high-frequency electric energy after voltage transformation; the second high-frequency electric energy including second high-frequency and high-voltage electric energy or second high-frequency and low-voltage electric energy; obtaining second low-frequency electric energy; the second low-frequency electric energy including second low-frequency and high-voltage electric energy or second low-frequency and low-voltage electric energy.

Provided are voltage and frequency transformation systems, methods and devices, and relate to the field of transformers. The method includes: inputting low-frequency electric energy with frequency lower than a first predetermined frequency threshold; the low-frequency electric energy including low-frequency and low-voltage electric energy or low-frequency and high-voltage electric energy; obtaining high-frequency electric energy with frequency higher than a second predetermined frequency threshold; the high-frequency electric energy including first high-frequency and low-voltage electric energy or first high-frequency and high-voltage electric energy; obtaining second high-frequency electric energy after voltage transformation; the second high-frequency electric energy including second high-frequency and high-voltage electric energy or second high-frequency and low-voltage electric energy; obtaining second low-frequency electric energy; the second low-frequency electric energy including second low-frequency and high-voltage electric energy or second low-frequency and low-voltage electric energy.