TW202215742A - Power conversion structure applied in sst and charging system having the same - Google Patents

Abstract

A power conversion structure applied in SST includes a DC link, a first capacitor, a second capacitor, and a power conversion module assembly. The DC link has a DC link positive end, a DC link negative end, and a DC link middle node. The first capacitor is coupled between the DC link negative end and the DC link middle node, and the second capacitor is coupled between the DC link negative end and the DC link middle node. The power conversion module assembly has a plurality of DC conversion modules. Input sides of the DC conversion modules are connected in series to form two input ends of the power conversion module assembly, and output sides of the DC conversion modules are connected in parallel to form two output ends of the power conversion module assembly. At least two power conversion module assemblies are connected with the first capacitor and the second capacitor in parallel through their own two input ends, respectively.

Description

Power conversion structure applied to solid state transformer and charging system with the power conversion structure

The present invention relates to a power conversion structure and a charging system having the power conversion structure, especially a power conversion structure applied to a solid state transformer and a charging system with the power conversion structure.

Please refer to FIG. 1 , which is a block diagram of a power system of a conventional high-power electric vehicle charging station. The power system is powered (generated) by a medium-voltage AC input power source V _AC , such as but not limited to a medium-voltage AC input power source with a voltage of 13.2 kilovolts (kV), and the AC input power source V _AC is connected to the AC input power source through electrical towers and transmission lines. sent to the transformer 10A. The transformer 10A is a line-frequency transformer, which is a transformer that operates at an operating frequency of a power grid (eg, 50 Hz or 60 Hz). However, the power frequency transformer is heavy, occupies a large space, and has high standby iron loss.

The 13.2 kV medium-voltage AC power V _AC is converted into a low-voltage AC power (eg, 480 volts) through the transformer 10A, and the low-voltage AC power is adjusted and converted by the power factor corrector 20A to generate a low-voltage DC power. Then, the low-voltage DC power source is converted into a DC output power source V _DC via a DC converter 30A (ie, a DC-DC converter), which is used as the output voltage of the charging station.

However, the traditional high-power electric vehicle charging station system, in addition to the above-mentioned shortcomings of the power frequency transformer, also has the problem of low system efficiency due to the large number of power conversion stages.

With the introduction of new power electronic components and the vigorous development of distributed power supply and smart grid, solid state transformer (SST) has become an increasingly popular research topic. Solid-state transformers have versatile and high-performance features, including integrating microgrids, correcting power factor, compensating for reactive power, isolating fault currents, and adjusting output voltages.

However, the power supply device applied to the solid state transformer structure still faces problems that need to be overcome, such as providing a flexible power supply configuration to meet different power supply requirements, and the goal of fast charging of electric vehicles with high efficiency and high safety. To this end, how to design a power conversion architecture for solid-state transformers and a charging system with the power conversion architecture to meet high-voltage and/or high-current charging requirements, and improve the flexibility and diversification of applications for electric vehicle charging requirements , and increasing the reliability of the charging system is an important subject studied by the inventor of the present application.

The purpose of the present invention is to provide a power conversion structure applied to a solid-state transformer, which solves the disadvantages of heavy weight, large space occupation, and high standby iron loss of traditional high-power electric vehicle charging stations using power frequency transformers. There are many stages, and there is a problem of low system efficiency.

In order to achieve the purpose disclosed above, the power conversion structure applied to the solid state transformer proposed by the present invention includes a DC link, a first capacitor, a second capacitor and a power conversion module group. The DC link has a DC link positive pole, a DC link negative pole, and a DC link neutral point. The first capacitor is coupled between the positive pole of the DC link and the neutral point of the DC link. The second capacitor is coupled between the negative pole of the DC link and the neutral point of the DC link. The power conversion module group includes a plurality of DC power conversion modules; wherein, the input sides of the plurality of DC power conversion modules are connected in series to form two input ends of the power conversion module group, and the plurality of DC power conversion modules The output sides are connected in parallel to form the two output ends of the power conversion module group. Wherein, at least two power conversion module groups are respectively connected in parallel with the first capacitor and the second capacitor through the respective two input ends.

In one embodiment, the respective two input ends of the at least two power conversion module groups are respectively connected in parallel with the first capacitor and the second capacitor, and the respective two output ends are connected in parallel.

In one embodiment, the respective two input ends of the at least two power conversion module groups are respectively connected in parallel with the first capacitor and the second capacitor, and the respective two output ends are connected in series.

In one embodiment, the number of at least two power conversion module groups is 2N, where N is a positive integer greater than or equal to 2; half of the power conversion module groups are connected in parallel with the first capacitors through their respective two input terminals, respectively, The other half of the power conversion module groups are connected in parallel with the second capacitors through their respective two input terminals; the power conversion module group connected in parallel with the first capacitor and the power conversion module group corresponding to the parallel second capacitor are connected in series through their respective two output terminals The connections are output ports to form a total number of N output ports, wherein the N output ports are connected in parallel.

In one embodiment, the number of at least two power conversion module groups is 2N, where N is a positive integer greater than or equal to 2; half of the power conversion module groups are connected in parallel with the first capacitors through their respective two input terminals, respectively, The other half of the power conversion module groups are connected in parallel with the second capacitors through their respective two input terminals; the power conversion module group connected in parallel with the first capacitor and the power conversion module group corresponding to the parallel second capacitor are connected in parallel through their respective two output terminals The connections are output ports to form a total number of N output ports, wherein the N output ports are connected in parallel.

In one embodiment, the power conversion architecture is used to power a charging station or an energy storage system.

Another object of the present invention is to provide a charging system applied to a solid-state transformer, which solves the disadvantages of heavy weight, large space occupation, and high standby iron loss of traditional high-power electric vehicle charging stations using power-frequency transformers. There are many stages of conversion, and there is a problem of low system efficiency.

In order to achieve the aforementioned purpose, the charging system applied to the solid state transformer proposed by the present invention includes an AC-DC conversion circuit, at least one power conversion structure, and at least one charging station. The AC-DC conversion circuit receives the input power, and converts the input power into a high-voltage DC voltage and provides it on the DC link. At least one power conversion structure is coupled to the DC link, receives the high voltage DC voltage and converts the high voltage DC voltage into at least one output voltage. At least one charging station is correspondingly coupled to at least one power conversion structure, and is powered by at least one output voltage.

In one embodiment, at least one power conversion architecture is connected in parallel.

In one embodiment, the circuit configurations of at least one power conversion architecture are the same, or at least one of them is different.

In one embodiment, the input power source is a medium voltage input power source.

Thereby, the power conversion architecture applied to the solid-state transformer and the charging system applied to the solid-state transformer proposed by the present invention can meet the charging requirements of high voltage and/or high current, and improve the flexibility and variety of applications for the charging requirements of electric vehicles and increase the reliability of the charging system.

In order to further understand the technology, means and effect adopted by the present invention to achieve the predetermined purpose, please refer to the following detailed description and accompanying drawings of the present invention. For specific understanding, however, the accompanying drawings are only provided for reference and description, and are not intended to limit the present invention.

The technical content and detailed description of the present invention are described as follows in conjunction with the drawings.

Please refer to FIG. 2 and FIG. 3 , which are respectively a circuit block diagram of a single power conversion module group of the present invention and a circuit block diagram of two power conversion module groups of the present invention connected to the DC link. The power conversion structure applied to the solid state transformer includes a DC link L _DC , a first capacitor C1 , a second capacitor C2 and a power conversion module group 10 . The DC link L _DC has a DC link positive pole P, a DC link negative pole N, and a DC link neutral point O. The first capacitor C1 is coupled between the positive pole P of the DC link and the neutral point O of the DC link; the second capacitor C2 is coupled between the negative pole N of the DC link and the neutral point O of the DC link. Basically, when the capacitances of the first capacitor C1 and the second capacitor C2 are equal, under normal operation, the electrical (cross) voltage across the first capacitor C1 and the electrical (cross) voltage across the second capacitor C2 will be equal, And it is half of the output voltage of the DC link L _DC . In one embodiment, the electrical (cross) voltage across the first capacitor C1 and the second capacitor C2 is 11 kilovolts (kV). Incidentally, in practical application, it is not limited to the structure that only includes the first capacitor C1 and the second capacitor C2 in series, that is, the present invention is not limited to using two capacitors connected in series between the two poles of the DC link , more than three capacitors can also be used in series, so the application of using N capacitors and N power conversion module groups should also be included in the scope of the present invention.

The power conversion module group 10 includes a plurality of DC power conversion modules 101, 102, . . . , 10n. As shown in FIG. 2, the DC power conversion modules 101, 102, ..., 10n are respectively a first DC power conversion module 101, a second DC power conversion module 102, ... and an Nth DC power conversion module 10n. Wherein, the input sides of the DC power conversion modules 101 , 102 , . . . , 10n are connected in series, so that the input side of the power conversion module group 10 has two input terminals In1 , In2 . The output sides of the DC power conversion modules 101, 102, . . . , 10n are connected in parallel, so that the output side of the power conversion module group 10 provides two output terminals Out1, Out2.

In the present invention, at least two power conversion module groups 10 are connected in parallel with the first capacitor C1 and the second capacitor C2 through the respective two input terminals In1 and In2 respectively. As shown in FIG. 3 , it is an embodiment in which two power conversion module groups 10 are connected to the DC link L _DC in parallel. Specifically, the power conversion module group 10 in the upper half of the circuit passes through its two input terminals In1 , In2 is connected in parallel with the first capacitor C1, and the power conversion module group 10 in the lower half of the circuit is connected in parallel with the second capacitor C2 through its two input terminals In1 and In2.

As shown in FIG. 4 , it is a circuit block diagram of the parallel power supply of the output sides of two power conversion module groups of the present invention. As mentioned above, the input sides of the two power conversion module groups 10 are connected in parallel with the first capacitor C1 and the second capacitor C2 respectively, and the respective output terminals Out1 and Out2 of the two power conversion module groups 10 are connected in parallel, providing The output power (power) of the battery can be used to charge (supply) a charging station 100 (shown in FIG. 4 ) or an energy storage system (not shown).

Specifically, the two power conversion module groups are respectively a first power conversion module group 11 and a second power conversion module group 12 , wherein the input side of the first power conversion module group 11 is connected in parallel with the first capacitor C1 and the second power conversion module group 11 in parallel. The input side of the power conversion module group 12 is connected in parallel with the second capacitor C2. In addition, the output terminals Out1 and Out2 of the first power conversion module group 11 are connected in parallel with the output terminals Out1 and Out2 of the second power conversion module group 12, and the provided output power (power) can be used for the charging station 100 or the storage device. It can charge (supply) power to the system.

For example, if each power conversion module group can provide an output voltage of 500 volts and an output current of 200 amperes, therefore, through the circuit configuration of FIG. 4 , the output voltage that can be provided to the charging station 100 is 500 volts, The output current is 400 amps (because the outputs of the first power conversion module group 11 and the output of the second power conversion module group 12 are connected in parallel), so a multiplied output current can be provided to meet the high current charging requirement.

As shown in FIG. 5 , which is a circuit block diagram of the present invention, the output side of two power conversion module groups are connected in series to supply power. As mentioned above, the input sides of the two power conversion module groups 10 are connected in parallel with the first capacitor C1 and the second capacitor C2 respectively, and the respective output terminals Out1 and Out2 of the two power conversion module groups 10 are connected in series, providing The output power (power) of the device can be used to charge (supply) the charging station 100 or the energy storage system.

Specifically, the two power conversion module groups are respectively a first power conversion module group 11 and a second power conversion module group 12 . The input side of the first power conversion module group 11 is connected in parallel with the first capacitor C1 , and the input side of the second power conversion module group 12 is connected in parallel with the second capacitor C2 . In addition, the output terminals Out1 and Out2 of the first power conversion module group 11 are connected in series with the output terminals Out1 and Out2 of the second power conversion module group 12, and the provided output power (power) can be used for the charging station 100 or the storage device. It can charge (supply) power to the system.

For example, if each power conversion module group can provide an output voltage of 500 volts and an output current of 200 amperes, therefore, through the circuit configuration of FIG. 5 , the output voltage that can be provided to the charging station 100 is 1000 volts, The output current is 200 amps (because the outputs of the first power conversion module group 11 and the second power conversion module group 12 are connected in series), so a multiplied output voltage can be provided to meet high-voltage charging requirements.

As shown in FIG. 6 , which is a circuit block diagram of the four power conversion module groups of the present invention, two output sides are connected in series and then powered in parallel. The number of at least two power conversion module groups is four; the two power conversion module groups are connected in parallel with the first capacitor C1 through their respective two input terminals, and the other two power conversion module groups are connected in parallel through their respective two input terminals. the second capacitor. One of the two power conversion module groups connected in parallel with the first capacitor C1 and one of the two power conversion module groups connected in parallel with the second capacitor C2 are connected in series through their respective two output terminals to form a first output port Po1, The other of the two power conversion module groups connected in parallel with the first capacitor C1 and the other of the two power conversion module groups connected in parallel with the second capacitor are connected in series to form a second output port Po2 through their respective two output terminals. The second output port Po2 and the first output port Po1 are connected in parallel.

Specifically, the four power conversion module groups are respectively a first power conversion module group 11 , a second power conversion module group 12 , a third power conversion module group 13 and a fourth power conversion module group 14 . The input sides of the first power conversion module group 11 and the third power conversion module group 13 are connected in parallel with the first capacitor C1, and the input sides of the second power conversion module group 12 and the fourth power conversion module group 14 are connected in parallel with the first capacitor C1. Two capacitors C2. In addition, the output terminals Out1 and Out2 of the first power conversion module group 11 and the output terminals Out1 and Out2 of the second power conversion module group 12 are connected in series to form the first output port Po1; the output of the third power conversion module group 13 The terminals Out1 and Out2 are connected in series with the output terminals Out1 and Out2 of the fourth power conversion module group 14 to form the second output port Po2. Then, the first output port Po1 and the second output port Po2 are connected in parallel, and the provided output power (power) can charge (supply) the charging station 100 or the energy storage system.

For example, if each power conversion module group can provide an output voltage of 500 volts and an output current of 200 amperes, therefore, through the circuit configuration of FIG. 6 , the output voltage that can be provided to the charging station 100 is 1000 volts, The output current is 400 amps (because the outputs of the first power conversion module group 11 and the second power conversion module group 12 are connected in series, and the outputs of the third power conversion module group 13 and the fourth power conversion module group 14 are connected in series, And the first output port Po1 and the second output port Po2 are connected in parallel), therefore, the multiplied output voltage and output current can be provided to meet the charging requirements of high voltage and high current.

As shown in FIG. 7 , which is a circuit block diagram of the four power conversion module groups of the present invention, two output sides are connected in parallel and then supply power in parallel. The number of at least two power conversion module groups is four; the two power conversion module groups are connected in parallel with the first capacitor C1 through their respective two input terminals, and the other two power conversion module groups are connected in parallel through their respective two input terminals. the second capacitor C2. One of the two power conversion module groups connected in parallel with the first capacitor C1 and one of the two power conversion module groups connected in parallel with the second capacitor C2 are connected in parallel to form a first output port Po1 through their respective two output terminals. The other of the two power conversion module groups connected in parallel with the first capacitor C1 and the other of the two power conversion module groups connected in parallel with the second capacitor are connected in parallel to form a second output port Po2 through their respective two output terminals. The second output port Po2 and the first output port Po1 are connected in parallel.

Specifically, the four power conversion module groups are respectively a first power conversion module group 11 , a second power conversion module group 12 , a third power conversion module group 13 and a fourth power conversion module group 14 . The input sides of the first power conversion module group 11 and the third power conversion module group 13 are connected in parallel with the first capacitor C1, and the input sides of the second power conversion module group 12 and the fourth power conversion module group 14 are connected in parallel with the first capacitor C1. Two capacitors C2. In addition, the output terminals Out1 and Out2 of the first power conversion module group 11 and the output terminals Out1 and Out2 of the second power conversion module group 12 are connected in parallel to form the first output port Po1; the output of the third power conversion module group 13 The terminals Out1 and Out2 are connected in parallel with the output terminals Out1 and Out2 of the fourth power conversion module group 14 to form the second output port Po2. Then, the first output port Po1 and the second output port Po2 are connected in parallel, and the provided output power (power) can charge (supply) the charging station 100 or the energy storage system.

For example, if each power conversion module group can provide an output voltage of 500 volts and an output current of 200 amperes, therefore, through the circuit configuration of FIG. 7 , the output voltage that can be provided to the charging station 100 is 500 volts, The output current is 800 amperes (because the outputs of the first power conversion module group 11 and the second power conversion module group 12 are connected in parallel, and the outputs of the third power conversion module group 13 and the fourth power conversion module group 14 are connected in parallel, And the first output port Po1 and the second output port Po2 are connected in parallel), therefore, 4 times the output current can be provided to meet the high current charging demand.

It is worth mentioning that in practical applications, the number of the power conversion module groups 10 is not limited to four, that is, a plurality of power conversion module groups in pairs (corresponding) can constitute the power conversion structure. For example, the number of the power conversion module groups 10 is 2N, where N is a positive integer greater than or equal to 2, and half of the power conversion module groups 10 are connected in parallel with the first capacitor C1 through their respective two input terminals. , the other half of the power conversion module group 10 are connected in parallel with the second capacitor C2 through their respective two input terminals, and are connected in parallel or in series through their respective two output terminals as an output port, so as to form a total number of N output ports , to provide higher output voltage and/or output current charging requirements.

Please refer to FIG. 8 , which is a block diagram of a charging system of the present invention applied to a solid state transformer. The charging system includes an AC-DC conversion circuit 91 , at least one power conversion structure 92 and at least one charging station 100 . The AC-DC conversion circuit 91 receives the input power V _AC , and converts the input power V _AC into a high-voltage DC voltage and provides it on the DC link L _DC . Wherein, the input power V _AC is a medium voltage input power, such as 13.2 kV, but it is not limited by this.

The at least one power conversion structure 92 is coupled to the DC link L _DC , receives the high voltage DC voltage and converts the high voltage DC voltage into at least one output voltage. The at least one charging station 100 is correspondingly coupled to the at least one power conversion structure 92 and is powered by the at least one output voltage. As shown in FIG. 8 , a plurality of power conversion structures 92 are connected in parallel at the input side, the input side is connected to the DC link L _DC at the output side of the AC-DC conversion circuit 91 , and the output sides are respectively connected to the charging station 100 . For example, if the number of power conversion structures 92 is four, the number of charging stations 100 is also four.

Furthermore, the at least one power conversion architecture 92 can be any one of the power conversion architectures of the four configurations described above in FIG. 4 to FIG. 7 . In other words, the configuration of each power conversion architecture 92 may be the same, or at least one of them may be different. Taking the four power conversion architectures 92 as an example, the configurations of the four power conversion architectures 92 may be the configurations shown in FIGS. 4 to 7 (that is, the configurations of the four power conversion architectures 92 are completely different), or the four power conversion architectures The configuration of the power conversion architectures 92 may also be one of the configurations of FIGS. 4 to 7 (ie, the configurations of the four power conversion architectures 92 are identical). Or, at least one is not the same and the others are the same.

To sum up, the present invention has the following features and advantages:

1. The configuration design of different power conversion architectures can meet the charging requirements of high voltage and/or high current.

2. The charging system provides a plurality of power conversion architectures, which can have the same or different circuit configurations to improve the flexibility and diversification of the application of electric vehicle charging requirements, and increase the reliability and high efficiency of the charging system. Fast charging with high security.

The above descriptions are only detailed descriptions and drawings of the preferred embodiments of the present invention, but the features of the present invention are not limited thereto, and are not intended to limit the present invention. The entire scope of the present invention should be defined as the following claims All the embodiments that conform to the spirit of the scope of the patent application of the present invention and similar variations thereof shall be included in the scope of the present invention. Modifications can be covered by the following patent scope of this case.

V _AC : AC input power

V _DC : DC output power supply

10A: Transformer

20A: Power Factor Corrector

30A: DC Converter

L _DC : DC link

P: DC link positive pole

N: DC link negative pole

O: DC link neutral point

C1: first capacitor

C2: second capacitor

10: Power conversion module group

101,102,...,10n: DC power conversion module

101: The first DC power conversion module

102: Second DC power conversion module

10n: Nth DC power conversion module

11: The first power conversion module group

12: The second power conversion module group

13: The third power conversion module group

14: The fourth power conversion module group

In1,In2: input terminal

Out1, Out2: output terminal

Po1: The first output port

Po2: The second output port

V _AC : Input Power

91: AC to DC conversion circuit

92: Power Conversion Architecture

100: Charging Station

Figure 1: It is a block diagram of the power system of a traditional high-power electric vehicle charging station.

FIG. 2 is a circuit block diagram of a single power conversion module group of the present invention.

FIG. 3 is a circuit block diagram of two power conversion module groups connected to a DC link according to the present invention.

FIG. 4 is a circuit block diagram showing the parallel power supply at the output sides of two power conversion module groups of the present invention.

FIG. 5 is a circuit block diagram showing the power supply in series at the output sides of two power conversion module groups according to the present invention.

FIG. 6 is a block diagram of a circuit in which two output sides of the four power conversion module groups of the present invention are connected in series and then powered in parallel.

FIG. 7 is a block diagram of a circuit in which two output sides of the four power conversion module groups of the present invention are connected in parallel and then supply power in parallel.

FIG. 8 is a block diagram of a charging system of the present invention applied to a solid state transformer.

L _DC : DC link

P: DC link positive pole

N: DC link negative pole

O: DC link neutral point

C1: first capacitor

C2: second capacitor

10: Power conversion module group

In1,In2: input terminal

Out1, Out2: output terminal

Claims (10)

A power conversion architecture applied to a solid state transformer, comprising: DC link, with DC link positive pole, DC link negative pole and DC link neutral point; a first capacitor, coupled between the positive electrode of the DC link and the neutral point of the DC link; a second capacitor coupled between the negative electrode of the DC link and the neutral point of the DC link; and A power conversion module group includes a plurality of DC power conversion modules; wherein, the input sides of the plurality of DC power conversion modules are connected in series to form two input ends of the power conversion module group, and the plurality of DC power conversion modules are connected in series. The output sides of the power conversion modules are connected in parallel to form two output ends of the power conversion module group; Wherein, at least two power conversion module groups are respectively connected in parallel with the first capacitor and the second capacitor through the respective two input ends. The power conversion structure applied to a solid state transformer according to claim 1, wherein the two input ends of the at least two power conversion module groups are connected in parallel with the first capacitor and the second capacitor respectively, and the two outputs of the respective The terminals are connected in parallel. The power conversion structure applied to a solid state transformer according to claim 1, wherein the two input ends of the at least two power conversion module groups are connected in parallel with the first capacitor and the second capacitor respectively, and the two outputs of the respective The terminals are connected in series. The power conversion architecture applied to a solid-state transformer according to claim 1, wherein the number of the at least two power conversion module groups is 2N, wherein N is a positive integer greater than or equal to 2; half of the power conversion module groups The group is connected in parallel with the first capacitor through its respective two input terminals, and the other half of the power conversion module group is connected in parallel with the second capacitor through its respective two input terminals; the power conversion module group connected in parallel with the first capacitor The power conversion module group corresponding to the second capacitor in parallel is connected in series to form an output port through the respective two output terminals, so as to form a total number of N output ports, wherein the N output ports are connected in parallel. The power conversion architecture applied to a solid-state transformer according to claim 1, wherein the number of the at least two power conversion module groups is 2N, wherein N is a positive integer greater than or equal to 2; half of the power conversion module groups The group is connected in parallel with the first capacitor through its respective two input terminals, and the other half of the power conversion module group is connected in parallel with the second capacitor through its respective two input terminals; the power conversion module group connected in parallel with the first capacitor The power conversion module group corresponding to the second capacitor in parallel is connected in parallel to form an output port through the respective two output terminals, so as to form a total number of N output ports, wherein the N output ports are connected in parallel. The power conversion structure applied to a solid state transformer as claimed in claim 1, wherein the power conversion structure is used to supply power to a charging station or an energy storage system. A charging system applied to a solid state transformer, comprising: an AC-DC conversion circuit, receiving an input power, and converting the input power into a high-voltage DC voltage and providing it on the DC link; at least one power conversion architecture, such as the power conversion architecture of any one of claims 1 to 6, coupled to the DC link, receiving the high-voltage DC voltage and converting the high-voltage DC voltage into at least one output voltage; and At least one charging station, correspondingly coupled to the at least one power conversion structure, is powered by the at least one output voltage. The charging system applied to a solid state transformer as claimed in claim 7, wherein the at least one power conversion structure is connected in parallel. The charging system applied to the solid state transformer as claimed in claim 7, wherein the circuit configurations of the at least one power conversion structure are the same, or at least one of them is different. The charging system applied to a solid state transformer as claimed in claim 7, wherein the input power source is a medium voltage input power source.

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