TWI749806B - 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 architecture applied to solid-state transformers and power conversion architecture Charging system

The present invention relates to a power conversion architecture and a charging system with a power conversion architecture, in particular to a power conversion architecture applied to a solid-state transformer and a charging system with the power conversion architecture.

Please refer to Figure 1, which is a block diagram of the power system of a traditional high-power electric vehicle charging station. The medium-voltage AC power system based input V _AC power supply (hair) power, such as but not limited to 13.2 kV medium voltage alternating current (kV) power supply voltage input through the electrical power lines and towers AC input power V _AC It is delivered to the transformer 10A. Wherein, the transformer 10A is a line-frequency transformer, which is a transformer that operates at a power grid operating frequency (for example, 50 Hz or 60 Hz). However, the power frequency transformer is heavy, occupies a large space, and high standby iron loss.

The 13.2 kV medium-voltage AC power source V _AC is converted into a low-voltage AC power source (for example, 480 volts) through a transformer 10A, and the low-voltage AC power source is adjusted and converted through a power factor corrector 20A to generate a low-voltage DC power source. 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-to-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 shortcomings of the above-mentioned power frequency transformer, due to the large number of power conversion stages, there is also a problem of low system efficiency.

With the development of power electronic components and the vigorous development of distributed power supplies and smart power grids, solid state transformers (SST) have become more and more popular research topics. Solid-state transformers have multi-functional and high-performance features, including integration of microgrids, power factor correction, reactive power compensation, fault current isolation, and output voltage adjustment.

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

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

In order to achieve the aforementioned purpose, the power conversion architecture applied to solid-state transformers 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 anode, a DC link cathode, 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; among them, 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 side is They are connected in parallel to form two output ends of the power conversion module group. Wherein, at least two power conversion module groups are connected in parallel with a first capacitor and a second capacitor through respective two input terminals.

In one embodiment, the two input terminals 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 output terminals of each are connected in parallel.

In one embodiment, the two input terminals 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 output terminals of each 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 number of power conversion module groups are connected in parallel with the first capacitors through their two input terminals, respectively, The other half of the power conversion module groups are connected in parallel with the second capacitors through their two input terminals; the power conversion module group with the first capacitor in parallel and the power conversion module group with the corresponding parallel second capacitor are connected in series through their two output terminals. Connected as output ports to form a total number of N output ports, of which 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 number of power conversion module groups are connected in parallel with the first capacitors through their two input terminals, respectively, The other half of the power conversion module groups are connected in parallel with the second capacitors through their two input terminals; the power conversion module group with the first capacitor in parallel and the power conversion module group with the corresponding parallel second capacitor are connected in parallel through their two output terminals. Connected as output ports to form a total number of N output ports, of which N output ports are connected in parallel.

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

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

In order to achieve the aforementioned purpose, the charging system applied to solid-state transformers proposed by the present invention includes an AC-DC conversion circuit, at least one power conversion structure, and at least one charging station. AC to DC conversion The 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 a 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 structure 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 is a medium voltage input power.

As a result, the power conversion architecture applied to solid-state transformers and the charging system applied to solid-state transformers proposed by the present invention can meet high-voltage and/or high-current charging requirements, and improve the flexibility and variety of electric vehicle charging applications. And increase the reliability of the charging system.

In order to further understand the technology, means and effects of the present invention to achieve the intended purpose, please refer to the following detailed description and drawings of the present invention. I believe that the purpose, features and characteristics of the present invention can be obtained from this in depth and For specific understanding, however, the accompanying drawings are only provided for reference and illustration, and are not intended to limit the present invention.

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

N: DC link negative pole

O: Neutral point of DC link

C1: The 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: The 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: 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.

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

Figure 3 is a block diagram of the circuit in which two power conversion module groups are connected to the DC link of the present invention.

Figure 4 is a block diagram of a circuit for parallel power supply on the output side of two power conversion module groups of the present invention.

Fig. 5 is a block diagram of a circuit for power supply in series on the output side 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 supplied 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 supplied in parallel.

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

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

Please refer to FIGS. 2 and 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 connected to the DC link of the present invention. The power conversion architecture 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 (trans) voltage at both ends of the first capacitor C1 and the electrical (trans) voltage at both ends of the second capacitor C2 will be equal. And it is half of the DC link L _DC output voltage. In one embodiment, the electrical (span) voltage across the first capacitor C1 and the second capacitor C2 is 11 kilovolts (kV). Incidentally, in practical applications, it is not limited to a structure that only includes the first capacitor C1 and the second capacitor C2 in series, which means that the present invention is not limited to using two capacitors in series between the two poles of the DC link. It is also possible to use more than three capacitors in series, so the application of using N capacitors with 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 Figure 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 and 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 respective two input terminals In1 and In2. 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 . 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 power supply in parallel on the output side of the 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 output terminals Out1 and Out2 of the two power conversion module groups 10 are connected in parallel. The output power (power) can charge (supply) power to a charging station (charging station) 100 (as shown in FIG. 4) or an energy storage system (not shown).

Specifically, the two power conversion module groups are 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 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, Out2 of the first power conversion module group 11 are connected in parallel with the output terminals Out1, Out2 of the second power conversion module group 12, and the provided output power (power) can be used for the charging station 100 or for storage The system can charge (supply) electricity.

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 Figure 4, the output voltage that can be provided to the charging station 100 is 500 volts, The output current is 400 amperes (because the first power conversion module group 11 is connected in parallel with the output of the second power conversion module group 12), therefore, a doubled output current can be provided to meet the high-current charging demand.

As shown in FIG. 5, it is a circuit block diagram of the power supply in series on the output side of the 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, and the output terminals Out1 and Out2 of the two power conversion module groups 10 are connected in series. The output power (power) can charge (supply) the charging station 100 or the energy storage system.

Specifically, the two power conversion module groups are the first power conversion module group 11 and the second power conversion module group 12 respectively. 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, Out2 of the first power conversion module group 11 are connected in series with the output terminals Out1, Out2 of the second power conversion module group 12, and the provided output power (power) can be used for the charging station 100 or for the storage The system can charge (supply) electricity.

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 Figure 5, the output voltage that can be provided to the charging station 100 is 1000 volts, The output current is 200 amperes (because the outputs of the first power conversion module group 11 and the second power conversion module group 12 are connected in series), therefore, a doubled output voltage can be provided to meet high-voltage charging requirements.

As shown in FIG. 6, it 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 supplied in parallel. The number of at least two power conversion module groups is four; two power conversion module groups are connected in parallel with the first capacitor C1 through their two input terminals, and the other two power conversion module groups are connected in parallel through their 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 to form a first output port Po1 through 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 through respective two output The output terminal is connected in series as the second output port Po2. Wherein, the second output port Po2 and the first output port Po1 are connected in parallel.

Specifically, the four power conversion module groups are 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 side 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 side of the second power conversion module group 12 and the fourth power conversion module group 14 are connected in parallel. Two capacitor C2. In addition, the output terminals Out1, Out2 of the first power conversion module group 11 and the output terminals Out1, 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, Out2 and the output terminals Out1, Out2 of the fourth power conversion module group 14 are connected in series 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 (power) 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 Figure 6, the output voltage that can be provided to the charging station 100 is 1000 volts, The output current is 400 amperes (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, a doubled output voltage and output current can be provided to meet the high voltage and high current charging requirements.

As shown in FIG. 7, it 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 supplied in parallel. The number of at least two power conversion module groups is four; two power conversion module groups are connected in parallel with the first capacitor C1 through their two input terminals, and the other two power conversion module groups are connected in parallel through their 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 is connected in parallel to form a first output port Po1 through 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 through their respective The two output terminals are connected in parallel to form the second output port Po2. Wherein, the second output port Po2 and the first output port Po1 are connected in parallel.

Specifically, the four power conversion module groups are 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 side 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 side of the second power conversion module group 12 and the fourth power conversion module group 14 are connected in parallel. Two capacitor C2. In addition, the output terminals Out1, Out2 of the first power conversion module group 11 and the output terminals Out1, 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 and the output terminals Out1 and Out2 of the fourth power conversion module group 14 are connected in parallel 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 (power) 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 amps, therefore, through the circuit configuration of Figure 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 4, that is, a plurality of power conversion module groups may be paired (corresponding) to form 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 respective two input terminals. , The other half of the power conversion module group 10 connects the second capacitor C2 in parallel through each of its two input terminals, and connects the two output terminals in parallel or in series to form an output port to form a total number of N output ports. , In order 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 applied to a solid-state transformer according to the present invention. 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 . Among them, the input power V _AC is a medium voltage input power, such as 13.2 kV, but this is not a limitation.

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 on the input side, the input side is connected to the DC link L _DC on the output side of the AC-DC conversion circuit 91, and the output side is 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 in the four configurations described above in FIGS. 4 to 7. In other words, the configuration of each power conversion structure 92 may be the same, or at least one may be different. Taking four power conversion architectures 92 as an example, the configurations of the four power conversion architectures 92 can be the configurations of FIGS. 4 to 7 (that is, the configurations of the four power conversion architectures 92 are completely different), or the four power conversion architectures 92 The configuration of each power conversion architecture 92 can also be one of the configurations of FIGS. 4 to 7 (that is, the configurations of the four power conversion architectures 92 are completely the same). Or, at least one is different and the others are the same.

In summary, the present invention has the following features and advantages:

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

2. The charging system provides multiple power conversion architectures, which can have the same or different circuit configurations to improve the flexibility and diversification of electric vehicle charging applications, and increase the reliability and high efficiency of the charging system. High-safety fast charging.

The above are only detailed descriptions and drawings of the preferred embodiments of the present invention. However, the features of the present invention are not limited to these, and are not intended to limit the present invention. The full scope of the present invention should be covered by the following patent application scope As the standard, all embodiments that conform to the spirit of the patent application of the present invention and similar changes should be included in the scope of the present invention. Anyone familiar with the art in the field of the present invention can easily think of changes or Modifications can be covered in the following patent scope of this case.

L _DC : DC link

P: DC link positive

N: DC link negative pole

O: Neutral point of DC link

C1: The 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 solid-state transformers, including: a DC link with a DC link positive, a DC link negative, and a DC link neutral point; a first capacitor coupled to the DC link positive and the DC link Between the neutral points; a second capacitor, coupled between the negative pole of the DC link and the neutral point of the DC link; and a power conversion module group, including a plurality of DC power conversion modules, and each of the DC power sources The conversion module is a single-stage power conversion architecture; 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 output of the plurality of DC power conversion modules The sides are connected in parallel to form two output terminals of the power conversion module group; wherein at least two power conversion module groups are connected in parallel with the first capacitor and the second capacitor through respective two input terminals. The power conversion architecture applied to a solid-state transformer according to claim 1, wherein the two input terminals of each of the at least two power conversion module groups are connected in parallel with the first capacitor and the second capacitor, and the two outputs of each The ends are connected in parallel. The power conversion architecture applied to a solid-state transformer according to claim 1, wherein the two input terminals of each of the at least two power conversion module groups are connected in parallel with the first capacitor and the second capacitor, and the two outputs of each The ends are connected in series. The power conversion architecture applied to solid-state transformers according to claim 1, wherein the number of the at least two power conversion module groups is 2N, where N is a positive integer greater than or equal to 1; half of the power conversion modules Groups connect the first capacitors in parallel through their two input terminals, and the other half of the power conversion module groups connect the second capacitors in parallel through their two input terminals. The power conversion module group connects the first capacitors in parallel. Through the power conversion module group corresponding to the second capacitor in parallel The respective two output ports are connected in series to form an output port to form a total number of N output ports, where the N output ports are connected in parallel. The power conversion architecture applied to solid-state transformers according to claim 1, wherein the number of the at least two power conversion module groups is 2N, where N is a positive integer greater than or equal to 1; half of the power conversion modules Groups connect the first capacitors in parallel through their two input terminals, and the other half of the power conversion module groups connect the second capacitors in parallel through their two input terminals. The power conversion module group connects the first capacitors in parallel. The power conversion module group corresponding to the second capacitor in parallel is connected in parallel through each of the two output terminals to form an output port to form a total number of N output ports, where the N output ports are connected in parallel. The power conversion architecture applied to solid-state transformers as described in claim 1, wherein the power conversion architecture 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 that receives an input power, and converts the input power into a high-voltage DC voltage and provides it on a DC link; at least one power conversion architecture, such as the request item The power conversion architecture described in any one of 1 to 6, which 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; and at least one charging station is correspondingly coupled to the at least one output voltage; A power conversion structure is powered by the at least one output voltage. The charging system applied to the solid-state transformer according to claim 7, wherein the at least one power conversion structure is connected in parallel. The charging system applied to the solid-state transformer according to claim 7, wherein the circuit configuration of the at least one power conversion architecture is the same, or at least one of them is different. The charging system applied to a solid-state transformer as described in claim 7, wherein the input power source is a medium voltage input power source.

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