Power devices and power systems based on solid-state transformer architecture

Abstract

A power supply device and a power system for a solid-state transformer architecture are disclosed. The power supply device for the solid-state transformer architecture includes an AC-to-DC converter, a first DC bus, and a plurality of bidirectional DC-DC converters. The first sides of the bidirectional DC-DC converters are coupled to the first DC bus, and the second sides of the bidirectional DC-DC converters are configured to form at least one second DC bus, the number of which is equal to the number of buses. The bidirectional DC-DC converters receive a bus voltage and convert the bus voltage to at least one DC voltage equal to the number of buses, or the bidirectional DC-DC converters receive at least one external DC voltage equal to the number of buses and convert the at least one external DC voltage to a bus voltage.

Description

[0001] This invention is a divisional application of the invention application filed on August 7, 2019, with application number 201910725524X and invention title: Power supply device and three-phase power supply system applied to solid-state transformer architecture. Technical Field

[0002] This invention relates to a power supply device and a three-phase power supply system, and particularly to a power supply device and a three-phase power supply system applied to a solid-state transformer architecture. Background Technology

[0003] With the continuous innovation of power electronic components and the rapid development of distributed power supplies and smart grids, solid-state transformers (SSTs) have become an increasingly popular research topic. SSTs possess multifunctional and high-performance characteristics, including integrating microgrids, correcting power factor, compensating for ineffective power, isolating fault currents, and regulating output voltage.

[0004] In the design of DC charging stations, maintaining electrical isolation from the AC power grid—meaning the DC side must be completely isolated from other lines (including grounding)—presents a significant challenge in circuit design and cost considerations. Consequently, research and development on directly incorporating electrical isolation into DC charging station designs is rare. Furthermore, designing for different voltage requirements to accommodate the charging needs of various electric vehicles is also a crucial aspect of DC charging station design.

[0005] Therefore, how to design a power supply device and a three-phase power supply system applicable to solid-state transformer architecture to solve the aforementioned technical problems is an important research topic for the inventors of this disclosure. Summary of the Invention

[0006] The purpose of this invention is to provide a power supply device applicable to a solid-state transformer architecture, thereby solving the problems of the prior art.

[0007] To achieve the aforementioned objectives, the present invention provides a power supply device for a solid-state transformer architecture, comprising an AC-to-DC conversion unit, a first DC bus, and a plurality of bidirectional DC conversion units. The AC-to-DC conversion unit has a first side and a second side, wherein the first side of the AC-to-DC conversion unit is coupled to an AC power supply. The first DC bus is coupled to the second side of the AC-to-DC conversion unit and has a bus voltage. Each bidirectional DC conversion unit has a first side and a second side, and is a single-stage or two-stage conversion architecture, wherein the first side of the bidirectional DC conversion unit is coupled to the first DC bus, and the second side of the bidirectional DC conversion unit is configured to form at least one second DC bus, the number of which is equal to the number of buses. The bidirectional DC conversion unit receives the bus voltage and converts the bus voltage to at least one DC voltage equal to the number of buses, or the bidirectional DC conversion unit receives at least one external DC voltage equal to the number of buses and converts the at least one external DC voltage to the bus voltage.

[0008] The proposed power supply device, applied to a solid-state transformer architecture, can provide different voltage requirements while meeting isolation requirements.

[0009] The purpose of this invention is to provide a three-phase power supply system applied to a solid-state transformer architecture, thereby solving the problems of the prior art.

[0010] To achieve the aforementioned objectives, the three-phase power supply system proposed in this invention, applied to a solid-state transformer architecture, wherein any phase AC power supply is connected in series with a plurality of AC-to-DC conversion units of the aforementioned power supply devices, and the second side of the bidirectional DC conversion unit is connected in parallel.

[0011] The proposed three-phase power supply system applied to a solid-state transformer architecture can provide different voltage requirements while meeting isolation requirements, and achieve the technical effects of voltage equalization and power supply balance.

[0012] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the drawings are provided for reference and illustration only and are not intended to limit the scope of this invention. Attached Figure Description

[0013] Figure 1A : This is a circuit block diagram of the first embodiment of the power supply device of the present invention applied to a solid-state transformer architecture.

[0014] Figure 1B : This is a circuit block diagram of a second embodiment of the power supply device of the present invention applied to a solid-state transformer architecture.

[0015] Figure 1C: This is a circuit block diagram of a third embodiment of the power supply device of the present invention applied to a solid-state transformer architecture.

[0016] Figure 2A : This is a circuit block diagram of the first embodiment of the bidirectional DC-DC conversion unit of the power supply device of the present invention.

[0017] Figure 2B : This is a circuit block diagram of a second embodiment of the bidirectional DC-DC conversion unit of the power supply device of the present invention.

[0018] Figure 3A : This is a circuit block diagram of the first embodiment of the power supply device of the present invention applied to an external device.

[0019] Figure 3B : This is a circuit block diagram of a second embodiment of the power supply device of the present invention applied to an external device.

[0020] Figure 3C : This is a circuit block diagram of a third embodiment of the power supply device of the present invention applied to an external device.

[0021] Figure 4 This is a circuit block diagram of a power supply device with a single-phase connection applied to a solid-state transformer architecture according to the present invention.

[0022] Figure 5 This is a circuit block diagram of a three-phase connection of a power supply device applied to a solid-state transformer architecture according to the present invention.

[0023] Explanation of reference numerals in the attached figures:

[0024] 11 AC to DC conversion unit

[0025] 12 First DC Bus

[0026] 13 Bidirectional DC-DC converter unit

[0027] 14 Second DC Bus

[0028] 131 First-stage conversion circuit

[0029] 132 boost / buck circuit

[0030] 21 Energy Storage System

[0031] 22 Photovoltaic cells

[0032] 23 charging stations

[0033] 211 Energy Storage System Converter

[0034] 221 Photovoltaic Cell Converter

[0035] 231 Charging Station Converter

[0036] Vac AC power

[0037] Vb bus voltage Detailed Implementation

[0038] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings.

[0039] Please see Figures 1A to 1C The diagrams shown are circuit block diagrams of the first to third embodiments of the power supply device of the present invention applied to a solid-state transformer architecture. The power supply device includes an AC-to-DC conversion unit 11, a first DC bus 12, and multiple bidirectional DC-DC conversion units 13.

[0040] The AC-to-DC conversion unit 11 has a first side and a second side, wherein the first side of the AC-to-DC conversion unit 11 is coupled to an AC power supply Vac, which may be a power grid. The AC-to-DC conversion unit 11 converts the AC power supply Vac into a DC power supply (hereinafter referred to as bus voltage or bus line voltage). A first DC bus 12 is coupled to the second side of the AC-to-DC conversion unit 11 and has the bus voltage Vb, that is, the bus voltage Vb is the DC voltage on the first DC bus 12.

[0041] Each bidirectional DC-DC converter 13 has a first side and a second side, and each bidirectional DC-DC converter 13 can be a single-stage conversion architecture or a two-stage conversion architecture, as will be explained later. Figures 1A to 1C As shown, the first side of the bidirectional DC-DC converter 13 is coupled to the first DC bus 12, that is, coupled to the second side of the AC-DC converter 11.

[0042] The second side of the bidirectional DC-DC converter 13 is configured to form at least one second DC bus 14, the number of which is one bus number. Figures 1A to 1C The diagram shows a power supply device with three isolated DC power supplies, but this is not intended to limit the invention. For ease of explanation, [the diagram is shown here]. Figures 1A to 1C Let's take an example. In Figure 1A In this configuration, since the three second sides of the three bidirectional DC-DC converter units 13 are connected in parallel with each other, the three second sides of the three bidirectional DC-DC converter units 13 are configured to form a second DC bus 14 with a bus quantity of 1.

[0043] exist Figure 1B In this configuration, since the two second sides of the first bidirectional DC-DC converter 13 and the second bidirectional DC-DC converter 13 are connected in parallel and coupled to each other, and the second side of the third bidirectional DC-DC converter 13 is configured separately, the three second sides of the three bidirectional DC-DC converters 13 form a second DC bus 14 with a bus quantity of 2. Incidentally, in... Figure 1BThe invention is not limited to the fact that the two second sides of the first bidirectional DC-DC converter 13 and the second bidirectional DC-DC converter 13 are connected in parallel. In other words, as long as the two second sides of any two bidirectional DC-DC converter 13 are connected in parallel and the second side of the remaining bidirectional DC-DC converter 13 is configured separately, the resulting second DC bus 14 with a bus quantity of 2 should be included in the scope of the invention.

[0044] exist Figure 1C In this configuration, since the three second sides of the three bidirectional DC-DC converters 13 are configured separately, the three second sides of the three bidirectional DC-DC converters 13 are configured to form a second DC bus 14 with a bus number of 3.

[0045] Incidentally, if the number of bidirectional DC-DC converters 13 is four, i.e., the number of buses is 4, then the number of second DC buses 14 that can be configured on the four second sides of the four bidirectional DC-DC converters 13 can be 1 to 4. Specifically, a quantity of 1 means that the four second sides of the four bidirectional DC-DC converters 13 are connected in parallel; a quantity of 4 means that the four second sides of the four bidirectional DC-DC converters 13 are configured individually; a quantity of 2 means that two of the four second sides of the four bidirectional DC-DC converters 13 are connected in parallel, and the other two are connected in parallel, or three of the four second sides of the four bidirectional DC-DC converters 13 are connected in parallel, and the remaining one is configured individually; a quantity of 3 means that two of the four second sides of the four bidirectional DC-DC converters 13 are connected in parallel, and the remaining two are configured individually. Therefore, for a quantity of N bidirectional DC-DC converters 13, the number of second DC buses 14 configured on their second sides can be 1 to N, and the configuration methods are as described above and will not be repeated here.

[0046] Please see Figure 2A and Figure 2B The diagrams shown are circuit block diagrams of the first and second embodiments of the bidirectional DC-DC conversion unit of the power supply device of the present invention. As mentioned above, each bidirectional DC-DC conversion unit 13 can be a single-stage conversion architecture or a two-stage conversion architecture, the former being as follows: Figure 2A As shown, the latter is as Figure 2B As shown. Figure 2A As shown, the single-stage conversion architecture of the bidirectional DC-DC converter 13 only has a first-stage conversion circuit 131. This first-stage conversion circuit 131 includes an isolation transformer and a primary-side resonant circuit and a secondary-side resonant circuit. The primary-side resonant circuit is coupled to the primary side of the isolation transformer, and the secondary-side resonant circuit is coupled to the secondary side of the isolation transformer. In this embodiment, the primary-side resonant circuit and the secondary-side resonant circuit can be symmetrical CLLC resonant circuits; therefore, the first-stage conversion circuit 131 is a CLLC resonant DC-DC power conversion circuit.

[0047] like Figure 2BAs shown, the two-stage conversion architecture of the bidirectional DC-DC converter 13 consists of a first-stage conversion circuit 131 and a second-stage conversion circuit (i.e., a boost / buck circuit 132). That is, compared to... Figure 2A As shown, the two-stage conversion architecture also includes a boost / buck circuit 132 as a second-stage conversion circuit. The boost / buck circuit 132 is used to provide boost or buck conversion. Depending on the specific application requirements, a single-stage bidirectional DC-DC converter 13 or a two-stage bidirectional DC-DC converter 13 can be selected. The two-stage bidirectional DC-DC converter 13 provides a wider conversion voltage range, i.e., better voltage dynamic regulation. For example, if the first side of the bidirectional DC-DC converter 13 is the input side and it is 1580 volts, then for a single-stage bidirectional DC-DC converter 13, the output voltage range of its second side is between 800 and 1000 volts, while for a two-stage bidirectional DC-DC converter 13, the output voltage range of its second side is between 200 and 1000 volts. Therefore, the two-stage bidirectional DC-DC converter 13 provides a wider conversion voltage range and achieves better voltage dynamic regulation.

[0048] Please see Figures 3A to 3C The diagram shown is a circuit block diagram of the first to third embodiments of the power supply device of the present invention applied to an external device. Taking three bidirectional DC-DC conversion units 13 as an example, in... Figure 3A In this configuration, the three second sides of the three bidirectional DC-DC converters 13 are arranged to form a second DC bus 14 with a bus quantity of one, and each bidirectional DC-DC converter 13 is a single-stage conversion architecture (i.e., it only has a first-stage conversion circuit 131). The power supply device can be electrically connected to external devices, such as an energy storage system (ESS) 21, a photovoltaic cell 22, and a charging station 23. Incidentally, the type and number of external devices electrically connected to the power supply device are not limited to... Figure 3A The limitation shown is that the power supply device can be electrically connected to multiple energy storage systems 21, photovoltaic cells 22, and charging stations 23.

[0049] In conjunction with the bidirectional DC-DC converter unit 13 of the single-stage conversion architecture, the energy storage system 21 requires an energy storage system converter 211, such as an ESS bidirectional charger, to convert power from the second DC bus 14 to the energy storage system 21, or vice versa. The photovoltaic cell 22 requires a photovoltaic cell converter 221, such as a converter with maximum power point tracking (PVMPPT), to convert power from the photovoltaic cell 22 to the second DC bus 14. The charging station 23 requires a charging station converter 231, such as an isolated charger, to convert power from the second DC bus 14 to the charging station 23, or vice versa. Therefore, in the bidirectional DC-DC converter unit 13 of the single-stage conversion architecture, for the energy storage system 21, the energy storage system converter 211 is equivalent to another stage of power converter; for the photovoltaic cell 22, the photovoltaic cell converter 221 is equivalent to another stage of power converter; and for the charging station 23, the charging station converter 231 is equivalent to another stage of power converter. However, according to the requirements of actual applications, for the architecture of the second DC bus 14 with a bus quantity of 1, it is not based on... Figure 3A The bidirectional DC-DC converter unit 13 shown in the single-stage conversion architecture is a limitation; that is, the bidirectional DC-DC converter unit 13 can also be implemented as a two-stage conversion architecture, mainly depending on the requirements of the downstream device or voltage range. Through the bidirectional DC-DC converter unit 13 with power transmission function, bidirectional power flow operations can be achieved, including the power flow direction from the bidirectional DC-DC converter unit 13 to the external device via the second DC bus 14, and the power flow direction from the external device to the bidirectional DC-DC converter unit 13 via the second DC bus 14, thereby improving the commonality and flexibility of external device applications.

[0050] exist Figure 3B In this configuration, the three second sides of the three bidirectional DC-DC converters 13 are configured to form a second DC bus 14 with a bus quantity of 2. The second sides of the first two bidirectional DC-DC converters 13 are configured to form one second DC bus 14. Each bidirectional DC-DC converter 13 is a single-stage conversion architecture (i.e., it only has a first-stage conversion circuit 131). The second side of the third bidirectional DC-DC converter 13 is configured separately to form another second DC bus 14, making the bidirectional DC-DC converter 13 a two-stage conversion architecture (i.e., it has both a first-stage conversion circuit 131 and a second-stage conversion circuit). The application operation of the first two bidirectional DC-DC converters 13 with external devices can be found in [reference needed]. Figure 3A The details and explanations will not be repeated here.

[0051] With the bidirectional DC-DC converter unit 13 featuring a two-stage conversion architecture, the charging station 23 does not require a charging station converter 231 (e.g., Figure 3A As shown, the second-stage conversion of the boost / buck circuit 132 can meet the charging station 23's demand for a wider voltage supply. Incidentally, the types and number of external devices electrically connected to the power supply unit are not limited to... Figure 3B The diagram shows limitations, namely that the power supply device can electrically connect multiple energy storage systems 21, photovoltaic cells 22, and charging stations 23, and, based on the needs of actual applications, the architecture of the second DC bus 14 with a bus count of 2 is not limited to... Figure 3B The bidirectional DC-DC converter 13 shown in the single-stage conversion architecture is a limitation; that is, the bidirectional DC-DC converter 13 can also be implemented as a two-stage conversion architecture, depending mainly on the requirements of the downstream device or voltage range.

[0052] exist Figure 3C In this configuration, the three second sides of the three bidirectional DC-DC converter units 13 are configured to form a second DC bus 14 with a bus quantity of 3, and each bidirectional DC-DC converter unit 13 has a two-stage conversion architecture (i.e., it has a first-stage conversion circuit 131 and a second-stage conversion circuit). With the two-stage conversion architecture of the bidirectional DC-DC converter units 13, the charging station 23 does not require a charging station converter 231; the photovoltaic cell 22 does not require a photovoltaic cell converter 221; and the energy storage system 21 does not require an energy storage system converter 211. The second-stage conversion of the boost / buck circuit 132 can meet the voltage power supply requirements of the charging station 23, the photovoltaic cell 22, and the energy storage system 21.

[0053] Incidentally, for ease of explanation, Figure 3A Figure 3C This description is merely to illustrate the connection relationship between a single power supply device and the energy storage system 21, photovoltaic cells 22, and charging station 23. However, in practical applications, a three-phase multi-group parallel coupling method will be used, which will be explained later. The following examples illustrate the application of power management and supply and demand in the power supply device, energy storage system 21, photovoltaic cells 22, and charging station 23. The AC power source Vac is taken as an example of a power grid, and the listed embodiments are for illustrative purposes only and are not intended to limit the invention.

[0054] First embodiment: If the charging station 23 requires 100kW of power, and the grid (AC power supply Vac) can only supply up to 50kW, then the insufficient power for the charging station 23 can be supplied through communication and coordination between the photovoltaic cell 22 and the energy storage system 21. For example, if the photovoltaic cell 22 can provide 50kW, the energy storage system 21 does not need to provide power. Or, if the photovoltaic cell 22 can provide 20kW, the energy storage system 21 can provide 30kW (or if the photovoltaic cell 22 can provide 30kW, the energy storage system 21 can provide 20kW), so that the grid, photovoltaic cell 22, and energy storage system 21 can provide sufficient power to the charging station 23. In other words, the functions of power management, dispatching, and improving power quality can be achieved through the control method of the power conditioning system (PCS).

[0055] Second embodiment: Generally, whether the grid prioritizes power supply or the photovoltaic cells 22 and energy storage system 21 prioritize power supply depends on the power supply period and electricity price (generation cost). For example, during peak electricity consumption periods (e.g., 10:00 AM to 2:00 PM), because the grid's generation cost is higher, the main power source for charging station 23 is provided by energy storage system 21 and / or photovoltaic cells 22 as much as possible. Any remaining power from charging station 23 is then provided by the grid. In this way, by reducing peak electricity consumption and combining it with time-of-use pricing, the technical effects of saving electricity and costs can be achieved. Conversely, during off-peak electricity consumption periods, because the grid's generation cost is lower, the main power source for charging station 23 is provided by the grid as much as possible. At the same time, the grid (and / or photovoltaic cells 22) can also charge energy storage system 21, enabling it to be in a fully charged state and providing backup and redundant power.

[0056] The power supply and demand of the present invention are not limited to the two situations mentioned above. Due to the consideration of power generation cost of the power grid, the change of power consumption of charging station 23, the unstable power supply characteristics of photovoltaic cell 22 due to weather factors, and the different energy storage conditions of energy storage system 21, the communication and coordination of the control mechanism can enable each device (unit) to play its best power supply efficiency, making power management and dispatch more flexible and applicable to various different power supply and demand situations.

[0057] Please see Figure 4 As shown, it is a circuit block diagram of a power supply device with a single phase connection applied to a solid-state transformer architecture according to the present invention. Figure 4 The diagram shows the connection of multiple power supply units on one phase of a three-phase power system, and the configuration of a single power supply unit is as follows: Figure 1C As shown: A second DC bus 14 with a quantity of 3 buses is formed by the three separate second-side configurations of the three bidirectional DC-DC converter units 13. However... Figure 4This is only one embodiment of the present invention; in other words, it can also be configured using a single power supply device. Figure 1A (Bus quantity is 1) or a single power supply unit configuration is Figure 1B The power supply devices are combined into a single-phase interconnection architecture with multiple isolated DC power supplies in a manner with 2 buses.

[0058] like Figure 4 As shown, the AC power supply Vac side is connected in series, while the second side of each bidirectional DC-DC conversion unit 13 is connected in parallel. Specifically, the number of power supply devices is determined by the ratio of the system voltage to the withstand voltage of each power supply device. For example, when the line-to-line voltage of the system is 13.2kV ​​(and the phase-to-phase voltage is 7.62kV), if each power supply device has a withstand voltage of 0.847kV, then the number of power supply devices per phase can be designed to be nine groups. Therefore, the AC-to-DC conversion units 11 of these nine groups of power supply devices are connected in series, while the bidirectional DC-DC conversion units 13 of each group of power supply devices are connected in parallel to provide DC voltage to the corresponding second DC bus 14, or to receive DC voltage from external devices to the second DC bus 14.

[0059] Please see Figure 5 As shown, it is a circuit block diagram of a three-phase connection of a power supply device applied to a solid-state transformer architecture according to the present invention. Figure 4 Each phase architecture shown can be combined into a three-phase multi-group architecture. Specifically, the AC power supply Vac side is connected in a Y-connection manner with the neutral point N grounded, and each group of power supply devices in the three phases can be connected in parallel and coupled to each other. Taking the number of power supply devices in each phase of the aforementioned nine groups as an example, by combining three, the second sides of the first 27 groups (9 groups each of R phase, S phase, and T phase) of bidirectional DC-DC converter units 13 are connected in parallel, the second sides of the second 27 groups of bidirectional DC-DC converter units 13 are connected in parallel, and the second sides of the third 27 groups of bidirectional DC-DC converter units 13 are connected in parallel. In this way, the technical effect of equal voltage and balanced power supply can be achieved. As mentioned above, the electrical energy required by the charging station 23 can be supplied by the DC voltage provided by the first 27 groups of bidirectional DC-DC converter units 13. Among them, the electrical energy required by the charging station 23 can be provided by the 27 groups of bidirectional DC-DC converter units 13 on an average basis, or proportionally, but the present invention is not limited by the power supply method described above.

[0060] Furthermore, in a three-phase power system, the AC-to-DC converters 11 coupled to each phase are controlled in an interleaved phase-shift manner. For example, if there are three sets of AC-to-DC converters 11, and each set is switched at 10 kHz with a phase angle difference of 120 degrees, the system frequency of each phase can be doubled to 30 kHz. This allows each set of AC-to-DC converters 11 to have a lower switching frequency, thereby improving efficiency, and also results in better total harmonic distortion (THD) of the system, allowing the use of smaller filter components.

[0061] In summary, the present invention has the following features and advantages:

[0062] 1. By using a bidirectional DC-DC converter with power transmission function, bidirectional power flow operation can be achieved, thereby improving the commonality and flexibility of external device applications.

[0063] 2. A bidirectional DC-DC converter with a single-stage conversion architecture that has better conversion efficiency can be used, or a bidirectional DC-DC converter with a two-stage conversion architecture that provides a wider conversion voltage range and better dynamic voltage regulation can be used to meet the needs of practical applications.

[0064] 3. In order to meet the different voltage and isolation requirements of charging stations, photovoltaic cells and energy storage systems, power supply devices with multiple isolated DC power supplies can provide different voltage requirements and meet isolation requirements, and improve the flexibility of power supply and demand.

[0065] 4. By connecting each group of power supply devices in the three phases in parallel, the technical effect of equal voltage and balanced power supply is achieved.

[0066] 5. By controlling the AC-DC conversion units of each phase through interleaved phase shifting, each AC-DC conversion unit can have a lower switching frequency, thereby improving efficiency, and the system can have better total harmonic distortion, allowing the use of smaller filter components.

[0067] The above description is merely a detailed description and accompanying drawings of preferred embodiments of the present invention, and the features of the present invention are not limited thereto, nor are they intended to limit the present invention. The entire scope of the present invention should be determined by the following claims. All embodiments that conform to the concept of the claims of the present invention and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the following claims of the present disclosure.

Claims

1. A power supply device applied to a solid-state transformer architecture, wherein, A plurality of power supply devices are assigned to a single phase of the power supply system, and each of the plurality of power supply devices comprises: An AC-to-DC converter has a first side and a second side, wherein the first side of the AC-to-DC converter is coupled to an AC power supply. A first DC bus is coupled to the second side of the AC-to-DC conversion unit and has a bus voltage; and A plurality of bidirectional DC-DC converters, each having a first side and a second side, and being a single-stage or two-stage conversion architecture, wherein the first side of the bidirectional DC-DC converter is coupled to the first DC bus, and the second side of the bidirectional DC-DC converter is configured to form at least one second DC bus, the number of the at least one second DC bus being a bus number; The bidirectional DC-DC converter receives the bus voltage and converts it into at least one DC voltage equal to the number of buses; or the bidirectional DC-DC converter receives at least one external DC voltage equal to the number of buses and converts the at least one external DC voltage into the bus voltage. The first side of each of the AC-to-DC converters in the plurality of power supply devices is connected in series to receive the system voltage provided by the power system. In this configuration, each of the second DC buses belonging to the plurality of bidirectional DC-DC conversion units in the plurality of power supply devices is connected in parallel in a corresponding number.

2. The power supply device applied to a solid-state transformer architecture as described in claim 1, wherein each of the bidirectional DC-DC conversion units comprises: A first-stage conversion circuit, comprising: An isolation transformer has a primary side and a secondary side; A primary-side resonant circuit, coupled to the primary side; and The primary side resonant circuit is coupled to the secondary side.

3. The power supply device applied to a solid-state transformer architecture as described in claim 1, wherein each of the bidirectional DC-DC conversion units comprises: A first-stage conversion circuit, comprising: An isolation transformer has a primary side and a secondary side; A primary-side resonant circuit, coupled to the primary side; and The primary side resonant circuit is coupled to the secondary side; and A second-stage conversion circuit is coupled to the secondary-side resonant circuit, wherein the second-stage conversion circuit is a boost / buck circuit.

4. The power supply device applied to a solid-state transformer architecture as claimed in claim 1, wherein the second side of the bidirectional DC-DC converter is configured to form the at least one second DC bus by pre-wiring or by switching.

5. The power supply device applied to a solid-state transformer architecture as described in claim 1, wherein if the number of bidirectional DC-DC conversion units is N, the number of buses is 1 to N.

6. The power supply device applied to a solid-state transformer architecture as described in claim 1, wherein the at least one second DC bus is coupled to at least one of a charging station, a photovoltaic cell, and an energy storage system.

7. The power supply device applied to a solid-state transformer architecture as described in claim 6, wherein the charging station is coupled to the at least one second DC bus via a charging station converter, the photovoltaic cell is coupled to the at least one second DC bus via a photovoltaic cell converter, and the energy storage system is coupled to the at least one second DC bus via an energy storage system converter.

8. The power supply device for a solid-state transformer architecture as claimed in claim 1, wherein the number of buses is multiple, and each of the second DC buses is coupled to an external device, wherein at least one of the external devices is provided with sufficient power by another external device when it cannot obtain sufficient power from the AC power source.

9. A power system for a solid-state transformer architecture, wherein a single-phase AC power supply of the power system is series-coupled to the AC-to-DC conversion unit of the power device for a solid-state transformer architecture as claimed in any one of claims 1 to 8, and the second side of the bidirectional DC conversion unit is correspondingly coupled in parallel.

10. The power system applied to a solid-state transformer architecture as described in claim 9, wherein the second side of each corresponding bidirectional DC-DC converter in the AC power supply is coupled in parallel.

11. The power system applied to a solid-state transformer architecture as described in claim 9, wherein the AC-to-DC conversion unit coupled to each phase is controlled in an interleaved phase-shift manner.

12. The power system applied to a solid-state transformer architecture as described in claim 9, wherein the number of multiple power devices coupled to each phase is determined by the ratio of the system voltage to the withstand voltage of each power device.

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