Four-port power electronic transformer based on hybrid modular multilevel converter
First Claim
1. A four-port power electronic transformer based on a hybrid modular multilevel converter (MMC), comprising:
- a hybrid MMC, direct current (DC)/DC converters, and an inverter, whereinthe DC/DC converter comprises a front stage part, a high frequency transformation part, and a back stage part, wherein an alternating current (AC) side of the front stage part is connected to a primary side of the high frequency transformation part, and a secondary side of the high frequency transformation part is connected to an AC side of the back stage part;
the inverter is a three-phase four-bridge arm inverter;
the MMC has three phases, each phase having two bridge arms, and each bridge arm comprising X first submodules, Y second submodules, and an inductor, wherein X+Y≥
N, N being the minimum number of modules required when the MMC works normally;
the first submodule comprises two half-bridge structures connected in series, comprising a DC capacitor C1, a DC capacitor C2, and four insulated gate bipolar transistors T1, T2, T3 and T4 with anti-paralleled diodes;
the T1, T2, T3, and T4 have collectors respectively connected to cathodes of their respective freewheeling diodes and emitters respectively connected to anodes of their respective freewheeling diodes;
an emitter of the T1 and a collector of the T2 are connected and used as an AC port A of the first submodule, a collector of the T1 and a positive electrode of the C1 are connected and used as a positive electrode port C of the first submodule, an emitter of the T2, a negative electrode of the C1, a collector of the T4, and a positive electrode of the C2 are connected and used as a port I of the first submodule, an emitter of the T4 and a collector of the T3 are connected and used as an AC port B of the first submodule, and an emitter of the T3 and a negative electrode of the C2 are connected and used as a negative electrode port D of the first submodule;
the positive electrode port C and the negative electrode port D of the first submodule are respectively connected to a positive electrode port and a negative electrode port of the front stage of the DC/DC converter connected to a DC side of the module;
the second submodule comprises a DC capacitor C3, a DC capacitor C4, and five insulated gate bipolar transistors T5, T6, T7, T8, and T9 with anti-paralleled diodes;
the T5, T6, T7, T8, and T9 have collectors respectively connected to cathodes of their respective freewheeling diodes and emitters respectively connected to anodes of their respective freewheeling diodes;
in the second submodule, an emitter of the T5 and a collector of the T6 are connected and used as an AC port E of the second submodule, a collector of the T5 and a positive electrode of the C3 are connected and used as a positive electrode port G of the second submodule, an emitter of the T6, an emitter of the T9, and a negative electrode of the C3 are connected, an emitter of the T7 and a collector of the T8 are connected and used as an AC port F of the second submodule, a collector of the T7, a collector of the T9, and a positive electrode of the C4 are connected and used as a port J of the second submodule, and an emitter of the T8 and a negative electrode of the C4 are connected and used as a negative electrode port H of the second submodule;
the positive electrode port G and the negative electrode port H of the second submodule are respectively connected to a positive electrode port and a negative electrode port of the front stage of the DC/DC converter connected to a DC side of the second submodule;
without considering redundancy, X+Y=N, (2X+2Y)Vc=Vdc, and vm=(2X+2Y)Vc, where Vdc is a voltage at a high-voltage DC side, Vc is a voltage of each DC capacitor, and vm is a phase voltage amplitude at a high-voltage AC side;
considering redundancy, the following relationship needs to be satisfied;
X+Y≥
N;
when the MMC has a DC fault ride-through capability, without considering redundancy, X and Y satisfy the following relationship;
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Abstract
Disclosed in the present invention is a four-port power electronic transformer based on a hybrid modular multilevel converter (MMCs). The four-port power electronic transformer includes a hybrid MMC, direct current (DC)/DC converters, and an inverter. Each DC/DC converter includes a front stage part, a high frequency transformation part and a back stage part. Compared with an existing power electronic transformer, the present invention has the following characteristics: an MMC module and a front stage of a DC/DC circuit connected to the MMC module jointly complete DC fault ride-through, and the number of adopted devices is small; the MMC module controls a DC voltage and the DC/DC circuit controls power; voltages of one or two capacitors in the module can be controlled independently or simultaneously; and the four-port power electronic transformer has four ports: a high-voltage DC port, a high-voltage alternating current (AC) port, a low-voltage DC port, and a low-voltage AC port, and is applicable to a high-voltage high-power scenario with multiple voltage types and levels, particularly to the energy internet to be used as an energy router and the like.
12 Citations
6 Claims
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1. A four-port power electronic transformer based on a hybrid modular multilevel converter (MMC), comprising:
- a hybrid MMC, direct current (DC)/DC converters, and an inverter, wherein
the DC/DC converter comprises a front stage part, a high frequency transformation part, and a back stage part, wherein an alternating current (AC) side of the front stage part is connected to a primary side of the high frequency transformation part, and a secondary side of the high frequency transformation part is connected to an AC side of the back stage part; the inverter is a three-phase four-bridge arm inverter; the MMC has three phases, each phase having two bridge arms, and each bridge arm comprising X first submodules, Y second submodules, and an inductor, wherein X+Y≥
N, N being the minimum number of modules required when the MMC works normally;the first submodule comprises two half-bridge structures connected in series, comprising a DC capacitor C1, a DC capacitor C2, and four insulated gate bipolar transistors T1, T2, T3 and T4 with anti-paralleled diodes; the T1, T2, T3, and T4 have collectors respectively connected to cathodes of their respective freewheeling diodes and emitters respectively connected to anodes of their respective freewheeling diodes; an emitter of the T1 and a collector of the T2 are connected and used as an AC port A of the first submodule, a collector of the T1 and a positive electrode of the C1 are connected and used as a positive electrode port C of the first submodule, an emitter of the T2, a negative electrode of the C1, a collector of the T4, and a positive electrode of the C2 are connected and used as a port I of the first submodule, an emitter of the T4 and a collector of the T3 are connected and used as an AC port B of the first submodule, and an emitter of the T3 and a negative electrode of the C2 are connected and used as a negative electrode port D of the first submodule;
the positive electrode port C and the negative electrode port D of the first submodule are respectively connected to a positive electrode port and a negative electrode port of the front stage of the DC/DC converter connected to a DC side of the module;the second submodule comprises a DC capacitor C3, a DC capacitor C4, and five insulated gate bipolar transistors T5, T6, T7, T8, and T9 with anti-paralleled diodes; the T5, T6, T7, T8, and T9 have collectors respectively connected to cathodes of their respective freewheeling diodes and emitters respectively connected to anodes of their respective freewheeling diodes; in the second submodule, an emitter of the T5 and a collector of the T6 are connected and used as an AC port E of the second submodule, a collector of the T5 and a positive electrode of the C3 are connected and used as a positive electrode port G of the second submodule, an emitter of the T6, an emitter of the T9, and a negative electrode of the C3 are connected, an emitter of the T7 and a collector of the T8 are connected and used as an AC port F of the second submodule, a collector of the T7, a collector of the T9, and a positive electrode of the C4 are connected and used as a port J of the second submodule, and an emitter of the T8 and a negative electrode of the C4 are connected and used as a negative electrode port H of the second submodule;
the positive electrode port G and the negative electrode port H of the second submodule are respectively connected to a positive electrode port and a negative electrode port of the front stage of the DC/DC converter connected to a DC side of the second submodule;without considering redundancy, X+Y=N, (2X+2Y)Vc=Vdc, and vm=(2X+2Y)Vc, where Vdc is a voltage at a high-voltage DC side, Vc is a voltage of each DC capacitor, and vm is a phase voltage amplitude at a high-voltage AC side;
considering redundancy, the following relationship needs to be satisfied;
X+Y≥
N;
when the MMC has a DC fault ride-through capability, without considering redundancy, X and Y satisfy the following relationship; - View Dependent Claims (2, 3, 4, 5, 6)
- a hybrid MMC, direct current (DC)/DC converters, and an inverter, wherein
Specification