A solid state transformer and power supply device

Abstract

A kind of solid state transformer and power supply equipment, for improving the fault tolerance operation capability of solid state transformer.For improving the fault tolerance operation capability of solid state transformer, the solid state transformer includes multiple power conversion units in parallel;Each power conversion unit includes multiple single-phase conversion units, each single-phase conversion unit includes first switching unit, voltage conversion unit and second switching unit;The first end of first switching unit is the first input end of single-phase conversion unit, and the second end is connected with the first input end of voltage conversion unit;The second input end of voltage conversion unit is connected with the first end of second switching unit, and the output end is connected with the output end of solid state transformer;The second end of second switching unit is the second input end of single-phase conversion unit, and the third end is connected with one of other single-phase conversion units;Voltage conversion unit includes multiple voltage conversion circuits in series.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power electronics, and particularly relates to a solid-state transformer and a power supply device. BACKGROUND

[0002] The solid-state transformer is also called a power electronic transformer. In the solid-state transformer, power electronic conversion technology and high-frequency electric energy conversion technology based on electromagnetic induction principle are combined to convert electric energy with one power characteristic into electric energy with another power characteristic.

[0003] The solid-state transformer is mainly applied to a medium-voltage power grid. The solid-state transformer can reduce the voltage output by the medium-voltage power grid and output the reduced voltage to a low-voltage power supply load. In the solid-state transformer, a plurality of power conversion units are usually included. Each power conversion unit includes a plurality of single-phase conversion units. Each single-phase conversion unit converts one phase of three-phase alternating current transmitted by the medium-voltage power grid. However, in the current solid-state transformer, one neutral line is shared by each single-phase conversion unit in the power conversion unit. When a device in any single-phase conversion unit fails, the work of other single-phase conversion units in the power conversion unit is affected, and the entire power conversion unit cannot be used, which reduces the conversion power of the solid-state transformer. SUMMARY

[0004] The present application provides a solid-state transformer and a power supply device to improve fault tolerance and conversion power of the solid-state transformer.

[0005] In a first aspect, the present application provides a solid-state transformer, which includes a plurality of power conversion units connected in parallel.

[0006] Specifically, each power conversion unit includes a plurality of single-phase conversion units. Each power conversion unit includes a plurality of single-phase conversion units. Each single-phase conversion unit includes a first switching unit, a voltage conversion unit, and a second switching unit. The first end of the first switching unit is the first input end of the single-phase conversion unit. The second end of the first switching circuit is connected to the first input end of the voltage conversion unit. The second input end of the voltage conversion unit is connected to the first end of the second switching unit. The output end of the voltage conversion unit is connected to the output end of the solid-state transformer. The second end of the second switching unit is the second input end of the single-phase conversion unit. The third end of the second switching unit is connected to one single-phase conversion unit in other single-phase conversion units. The voltage conversion unit includes a plurality of voltage conversion circuits connected in series. When any voltage conversion circuit fails, the voltage conversion unit controls the connected first switching unit and second switching unit to be disconnected. When other single-phase conversion units fail, the voltage conversion unit disconnects the connection with the faulty single-phase conversion unit through the connected second switching unit.

[0007] With the solid state transformer, when a voltage conversion unit in any single-phase conversion unit fails, the single-phase conversion unit not failing can disconnect with the single-phase conversion unit failing, so as to isolate the fault source, at this time only the single-phase conversion unit failing cannot work, and the other single-phase conversion units not failing can still work normally, the fault tolerance capability of the solid state transformer is improved, and the conversion power of the solid state transformer is improved since the whole power conversion unit does not need to be disconnected.

[0008] In a possible implementation, the voltage conversion circuit comprises: a first power conversion circuit, a high-frequency transformer, and a second power conversion circuit; the first power conversion circuit and the second power conversion circuit are coupled through the high-frequency transformer.

[0009] With the solid state transformer, the first power conversion circuit and the second power conversion circuit are connected with an external power supply and a load respectively, and output a voltage required by the load through conversion processing.

[0010] In a possible implementation, the first switching unit comprises a first switch.

[0011] Specifically, a first electrode of the first switch constitutes a first end of the first switching unit, and a second electrode of the first switch constitutes a second end of the first switching unit and is connected with the first input end of the voltage conversion unit.

[0012] With the solid state transformer, the connection mode of the voltage conversion unit connecting with the external power supply can be controlled by controlling the state of the first switch.

[0013] In a possible implementation, the second switching unit comprises a second switch and a third switch.

[0014] Specifically, a first electrode of the second switch and a first electrode of the third switch are both connected with the second input end of the voltage conversion unit. A second electrode of the second switch is the second input end of the single-phase conversion unit. A second electrode of the third switch is connected with one of the other single-phase conversion units. The second input end of the single-phase conversion unit is connected with one of the other single-phase conversion units, and the second electrode of the second switch is connected with the second electrode of the third switch, and the single-phase conversion unit is different from the one of the other single-phase conversion units.

[0015] With the solid state transformer, the connection state with the other single-phase conversion units can be controlled by controlling the states of the second switch and the third switch, when a certain single-phase conversion unit fails, the connection between the single-phase conversion unit failing and the single-phase conversion unit not failing can be disconnected by controlling the second switch or the third switch, so as to isolate the fault source and ensure that the single-phase conversion unit not failing can work normally.

[0016] In a possible implementation, one of the plurality of voltage conversion circuits is a target voltage conversion circuit, and the target voltage conversion circuit is connected with the first switching unit and the second switching unit respectively. The target voltage conversion circuit is specifically configured to: control the connected first switching unit and the second switching unit to be disconnected when any voltage conversion circuit fails; or control the connected second switching unit to be disconnected from the failed single-phase conversion unit when another single-phase conversion unit fails.

[0017] With the solid-state transformer, the target voltage conversion circuit controls the states of the two switching units.

[0018] In a possible implementation, the plurality of voltage conversion circuits includes a first voltage conversion circuit and a second voltage conversion circuit. The first voltage conversion circuit is connected with the first switching unit. The second voltage conversion circuit is connected with the second switching unit.

[0019] Specifically, the first voltage conversion circuit can control the connected first switching unit to be disconnected when any voltage conversion circuit fails; the second voltage conversion circuit can control the connected second switching unit to be disconnected when any voltage conversion circuit fails; or control the connected second switching unit to be disconnected from the failed single-phase conversion unit when another single-phase conversion unit fails.

[0020] With the solid-state transformer, the first voltage conversion circuit controls the state of the first switching unit, and the second voltage conversion circuit controls the state of the second switching unit.

[0021] In a possible implementation, the power conversion unit further includes a protection unit connected with the first end of the first switching unit.

[0022] In a possible implementation, there is a first transmission channel between the plurality of voltage conversion circuits, and each voltage conversion circuit determines the failure state of another voltage conversion circuit according to the first transmission channel.

[0023] With the solid-state transformer, the plurality of voltage conversion circuits can communicate through the first transmission channel, so as to determine the failure state between the plurality of voltage conversion circuits.

[0024] In a possible implementation, there is a second transmission channel between the plurality of single-phase conversion units, and each single-phase conversion unit determines the failure state of another single-phase conversion unit according to the second transmission channel.

[0025] With the solid-state transformer, the plurality of single-phase conversion units can communicate through the second transmission channel, so as to determine the failure state between the plurality of single-phase conversion units.

[0026] Secondly, embodiments of this application provide a power supply device, which includes a cabinet and a solid-state transformer provided in the first aspect of this application and any possible design thereof. The solid-state transformer is disposed inside the cabinet, and its conductive casing is grounded through the cabinet. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating an application scenario of a solid-state transformer provided in an embodiment of this application;

[0028] Figure 2 This is a schematic diagram of the structure of a single-phase conversion unit provided in an embodiment of this application;

[0029] Figure 3 This application provides a schematic diagram of a voltage conversion circuit failure.

[0030] Figure 4 This is a schematic diagram of the structure of a solid-state transformer provided in an embodiment of this application;

[0031] Figure 5 This is a schematic diagram of the structure of a power conversion unit provided in an embodiment of this application;

[0032] Figure 6 This is a schematic diagram of the structure of a first switching unit provided in an embodiment of this application;

[0033] Figure 7 This is a schematic diagram of a voltage conversion circuit provided in an embodiment of this application;

[0034] Figure 8 A schematic diagram illustrating the working process of a solid-state transformer provided in an embodiment of this application;

[0035] Figure 9 This is a schematic diagram of the structure of a second switching unit provided in an embodiment of this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the application will now be described in further detail with reference to the accompanying drawings.

[0037] To facilitate understanding of the solid-state transformer provided in the embodiments of this application, its application scenarios will be introduced first below.

[0038] A solid state transformer can be used as an intermediate device between a power grid and a load device to convert the voltage in the power grid for use by the load device. Typically, the solid state transformer connects a medium voltage power grid and a low voltage load. For example, in a data center, which typically contains multiple load devices (e.g., servers), the power supply to the computer room is typically medium voltage (e.g., 10 kV) AC power, while the load devices in the data center typically require low voltage (e.g., 220 V or 400 V) DC or AC power. Therefore, the voltage of the medium voltage power grid can be processed by the solid state transformer to convert the voltage to the size and type required by the load device. Alternatively, in some other application scenarios, the solid state transformer can also convert the power generated on the low voltage side and deliver it to the medium voltage power grid. For example, the solid state transformer can connect the medium voltage power grid and a photovoltaic power station. The solid state transformer can process the power generated by the photovoltaic power station to step up the voltage, and then deliver the converted power to the medium voltage power grid.

[0039] As shown in FIG. 1, it is a schematic diagram of an application scenario of a solid state transformer. As shown in FIG. 2, the solid state transformer is connected with a power grid 01 and a load device 02, respectively. In a specific application, the power transmitted by the power grid 01 can be three-phase AC power. Specifically, the three-phase AC power can be composed of three single-phase AC powers with a phase difference of 120 degrees, and the three single-phase AC powers can be A-phase AC power, B-phase AC power and C-phase AC power, respectively. Each single-phase AC power can be connected with a single-phase conversion unit 11 in the solid state transformer, and each single-phase conversion unit 11 can convert the received single-phase AC power. Through multiple single-phase conversion units 11, the three-phase AC power transmitted by the power grid 01 can be converted to low voltage AC or DC power for use by the load device 02. The multiple single-phase conversion units 11 constitute a power conversion unit. Figure 1 Figure 1 As shown in FIG. 1, it is a schematic diagram of an application scenario of a solid state transformer. As shown in FIG. 2, the solid state transformer is connected with a power grid 01 and a load device 02, respectively. In a specific application, the power transmitted by the power grid 01 can be three-phase AC power. Specifically, the three-phase AC power can be composed of three single-phase AC powers with a phase difference of 120 degrees, and the three single-phase AC powers can be A-phase AC power, B-phase AC power and C-phase AC power, respectively. Each single-phase AC power can be connected with a single-phase conversion unit 11 in the solid state transformer, and each single-phase conversion unit 11 can convert the received single-phase AC power. Through multiple single-phase conversion units 11, the three-phase AC power transmitted by the power grid 01 can be converted to low voltage AC or DC power for use by the load device 02. The multiple single-phase conversion units 11 constitute a power conversion unit.

[0040] In actual use, when the solid state transformer is applied to a power conversion scenario, the conversion power of a single power conversion unit is limited. In order to realize large power conversion and meet the needs of the load device 02, multiple power conversion units can be provided in the solid state transformer, and the multiple power conversion units can be connected in parallel, and each power conversion unit converts a part of the power received by the solid state transformer.

[0041] As shown in FIG. 1, it is a schematic diagram of an application scenario of a solid state transformer. As shown in FIG. 2, the solid state transformer is connected with a power grid 01 and a load device 02, respectively. In a specific application, the power transmitted by the power grid 01 can be three-phase AC power. Specifically, the three-phase AC power can be composed of three single-phase AC powers with a phase difference of 120 degrees, and the three single-phase AC powers can be A-phase AC power, B-phase AC power and C-phase AC power, respectively. Each single-phase AC power can be connected with a single-phase conversion unit 11 in the solid state transformer, and each single-phase conversion unit 11 can convert the received single-phase AC power. Through multiple single-phase conversion units 11, the three-phase AC power transmitted by the power grid 01 can be converted to low voltage AC or DC power for use by the load device 02. The multiple single-phase conversion units 11 constitute a power conversion unit. Figure 2 As shown in FIG. 1, it is a schematic diagram of an application scenario of a solid state transformer. As shown in FIG. 2, the solid state transformer is connected with a power grid 01 and a load device 02, respectively. In a specific application, the power transmitted by the power grid 01 can be three-phase AC power. Specifically, the three-phase AC power can be composed of three single-phase AC powers with a phase difference of 120 degrees, and the three single-phase AC powers can be A-phase AC power, B-phase AC power and C-phase AC power, respectively. Each single-phase AC power can be connected with a single-phase conversion unit 11 in the solid state transformer, and each single-phase conversion unit 11 can convert the received single-phase AC power. Through multiple single-phase conversion units 11, the three-phase AC power transmitted by the power grid 01 can be converted to low voltage AC or DC power for use by the load device 02. The multiple single-phase conversion units 11 constitute a power conversion unit.​

[0042] In actual use, the number of voltage conversion circuits in the single-phase conversion unit 11 can be set according to the voltage amplitude of the single-phase alternating current and the conversion capacity of a single voltage conversion circuit, which is not specifically limited herein.

[0043] In actual application, the plurality of single-phase conversion units in each power conversion unit use the same neutral line N, as shown in FIG. 1, when a voltage conversion circuit in any single-phase conversion unit fails, the potential of the neutral line N will change, and the voltage amplitude borne by the single-phase conversion units that do not fail will change, that is, the working condition of the single-phase conversion units that do not fail changes, affecting the normal work of the single-phase conversion units that do not fail. In actual use, in order to ensure the safety of the solid-state transformer and the devices connected with the solid-state transformer, the power conversion unit in which the single-phase conversion unit fails will be closed, but this working mode will obviously reduce the conversion power of the solid-state transformer. Figure 3

[0044] Therefore, the embodiment of the present application provides a solid-state transformer capable of improving fault tolerance operation ability and conversion power in the case of failure of a single-phase conversion unit.

[0045] In order to clearly understand the solid-state transformer provided by the present application, the following will be specifically described in combination with the drawings and specific embodiments.

[0046] The terms used in the following embodiments are only for the purpose of describing specific embodiments and are not intended to be limiting to the present application. As used in the specification and the appended claims of the present application, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “at least one,” “one or more,” as used in the following embodiments, mean one, two, or more than two. The term “and / or” is used to describe the association relationship of the associated objects, which means that there can be three relationships; for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone, where A and B can be singular or plural. The character “ / ” generally represents an “or” relationship between the associated objects.

[0047] ​The specific operation methods in the method embodiments can also be applied to the device embodiments or the system embodiments. It should be noted that in the description of the present application, "multiple" only refers to "two or more". The association relationship of "and / or" between the associated objects indicates that there can be three relationships, for example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / ", if not specially stated, generally represents an "or" relationship between the associated objects. In addition, it should be understood that in the description of the present application, "first", "second", and the like are only used for distinguishing purposes and cannot be understood as indicating or implying relative importance or indicating or implying sequence.

[0048] It should be noted that the "connection" in the embodiments of the present application can be an electrical connection or a communication connection. The electrical connection between two electrical elements can be a direct or indirect connection between the two electrical elements. For example, A is connected to B, which can be that A is directly connected to B, or A is indirectly connected to B through one or more other electrical elements, for example, A is connected to B, which can be that A is directly connected to C, C is directly connected to B, and A is connected to B through C.

[0049] In the present specification, the reference to "one embodiment" or "some embodiments" and the like means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present application. Therefore, the statements "in one embodiment", "in some embodiments", "in other some embodiments", "in further some embodiments" and the like appearing in various places in the present specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "include", "contain", "have" and their variants mean "include but not limited to", unless otherwise specifically emphasized.

[0050] It should be noted that the switch tube in the embodiments of the present application can be one or more of a relay, a metal oxide semiconductor field effect transistor (MOSFET), a bipolar junction transistor (BJT), an insulated gate bipolar transistor (IGBT), a gallium nitride field effect transistor (GaN), a silicon carbide (SiC) power tube, and the like. The embodiments of the present application do not list them one by one. Each switching device can include a first electrode, a second electrode, and a control electrode, wherein the control electrode is used to control the conduction or disconnection of the switching device. When the switching device is on, current can be transmitted between the first electrode and the second electrode of the switching device, and when the switching device is off, current cannot be transmitted between the first electrode and the second electrode of the switching device. Taking the MOSFET as an example, the control electrode of the switching device is the gate, the first electrode of the switching device can be the source of the switching device, and the second electrode can be the drain of the switching device, or the first electrode can be the drain of the switching device, and the second electrode can be the source of the switching device.

[0051] As shown in Figure 4 , a solid-state transformer is provided in the embodiments of the present application. As shown in Figure 4 , the solid-state transformer 40 includes a plurality of power conversion units 41 connected in parallel. Each power conversion unit 41 respectively converts a part of the power received by the solid-state transformer 40 to enable the solid-state transformer 40 to achieve large power conversion.

[0052] As shown in Figure 5 , each power conversion unit 41 includes a plurality of single-phase conversion units 411, and each single-phase conversion unit 411 includes a first switching unit 4111, a voltage conversion unit 4112, and a second switching unit 4113.

[0053] Specifically, the first end of the first switching unit 4111 is the first input end of the single-phase conversion unit 411, and the second end of the first switching circuit 4111 is connected with the first input end of the voltage conversion unit 4112; the second input end of the voltage conversion unit 4112 is connected with the first end of the second switching unit 4113, and the output end of the voltage conversion unit 4112 is connected with the output end of the solid-state transformer 40; the second end of the second switching unit 4113 is the second input end of the single-phase conversion unit 411, and the third end of the second switching unit 4113 is connected with one of the other single-phase conversion units 411.

[0054] If any voltage conversion circuit in the single-phase conversion unit 411 fails, the single-phase conversion unit can be regarded as a failed single-phase conversion unit.

[0055] In a specific implementation, the second input end of the single-phase conversion unit 411 is connected to one of the other single-phase conversion units 411 in the plurality of single-phase conversion units, and the third end of the second switching unit 4113 is connected to another single-phase conversion unit 411 in the other single-phase conversion units 411, so as to realize the connection between the single-phase conversion units 411 in the power conversion unit 41.

[0056] It should be understood that Figure 5 The power conversion unit 41 only shows three single-phase conversion units 411, and in actual use, the number of single-phase conversion units 411 in the power conversion unit 41 can be more. It should be understood that when the power conversion unit 41 includes a plurality of single-phase conversion units 411, in order to realize the connection between the single-phase conversion units 411, the second switching unit 4113 in the single-phase conversion unit 411 needs to be provided with a corresponding number of ports. For example, when the number of single-phase conversion units 411 in the power conversion unit 41 is 5, the number of ports of the second switching unit 4113 can be 5, one of which is connected to the voltage conversion unit 4112, and the other four are respectively connected to the other single-phase conversion units 411 in the power conversion unit 41.

[0057] Next, taking the power conversion unit 41 including three single-phase conversion units 411 as an example for description.

[0058] In actual use, the voltage conversion unit 4112 includes a plurality of voltage conversion circuits 41121 connected in series, and the voltage conversion unit 4112 is configured to control the first switching unit 4111 and the second switching unit 4113 connected thereto to be disconnected when any voltage conversion circuit 41121 fails, or to disconnect the connection between the failed single-phase conversion unit 411 and the second switching unit 4113 connected thereto when the other single-phase conversion unit 411 fails.

[0059] Specifically, the input end of the solid-state transformer 40 is connected to a medium-voltage power grid, and the output end of the solid-state transformer 40 is connected to a load device. The medium-voltage power grid can adopt a three-phase three-wire transmission mode, that is, the medium-voltage power grid includes three phase lines, and each phase line outputs a single-phase alternating current.

[0060] Each single-phase conversion unit 411 has a first input end connected to one phase line of the medium-voltage power grid, and a second input end and a third end of the second switching unit 4113 are respectively connected to one single-phase conversion unit, thereby constituting a neutral line N and realizing balance between three-phase alternating currents, so as to receive single-phase alternating current and convert the received single-phase alternating current.

[0061] In actual use, each phase line and the neutral line N form an electric energy transmission path through the single-phase conversion unit 411, and transmit single-phase alternating current to the single-phase conversion unit 411, and the single-phase conversion unit 411 converts the received single-phase alternating current.

[0062] In actual application, the neutral line connected by the single-phase conversion unit 411 in each power conversion unit 41 is the same, and the neutral line connected by each power conversion unit 41 is different, so that each power conversion unit 41 can work independently.

[0063] In combination Figure 5 As shown, the first switching unit 4111 is connected with a phase line of the medium-voltage power grid, and the second input end and the third end of the second switching unit 4113 are connected with other single-phase conversion units 411 in the power conversion unit 41 to form the neutral line N. Therefore, when a single-phase conversion unit 411 fails, the first switching unit 4111 and the second switching unit 4113 in the failed single-phase conversion unit 411 can be controlled to be disconnected, so that the failed single-phase conversion unit 411 is disconnected from the medium-voltage power grid and other single-phase conversion units 411 that do not fail, the source of the fault is isolated, the single-phase conversion units 411 that do not fail can work normally, the power conversion unit 41 can continue to run in the case of single-phase conversion unit 411 failure, and the fault tolerance operation ability and conversion efficiency of the solid-state transformer 40 are improved.

[0064] In actual application, the solid-state transformer 40 can be fixedly connected with the medium-voltage power grid and the load device. In another implementation manner, the solid-state transformer 40 can be arranged in a flexible and detachable form. For example, the solid-state transformer 40 is provided with a fixed interface, the medium-voltage power grid can be connected with the solid-state transformer 40 through the fixed interface, and the load device can also be connected with the solid-state transformer 40 through the fixed interface. In this case, the solid-state transformer 40 is a device independent of the medium-voltage power grid and the load device.

[0065] Next, the first switching unit 4111, the voltage conversion unit 4112 and the second switching unit 4113 in the single-phase conversion unit 411 will be described in detail.

[0066] I. The first switching unit 4111

[0067] The first end of the first switching unit 4111 is the first input end of the single-phase conversion unit 411, the second end of the first switching unit 4111 is connected with the first input end of the voltage conversion unit 4112, and the first switching unit 4111 can realize the connection of the voltage conversion unit 4112 with the first input end of the solid-state transformer 40.

[0068] The first switching unit 4111 is configured to be controlled to be disconnected when any voltage conversion circuit 41121 in the voltage conversion unit 4112 fails, so as to disconnect the voltage conversion unit 4112 from the medium voltage grid, and avoid the expansion of the failure range.

[0069] The first switching unit 4111 can include a first switch. The first electrode of the first switch is the first end of the first switching unit 4111, and is connected to the first input end of the single-phase conversion unit 411. The second electrode of the first switch is the second end of the first switching unit 4111, and is connected to the first input end of the voltage conversion unit 4112.

[0070] In actual use, the control electrode of the first switch is connected to the voltage conversion unit 4112. When a failure occurs in a voltage conversion circuit 41121 in the connected voltage conversion unit 4112, the control electrode of the first switch will receive the driving signal sent by the voltage conversion unit 4112, and drive the first switch to be disconnected, so as to disconnect the voltage conversion unit 4112 from the phase line, and inhibit the expansion of the failure range.

[0071] In an example, the first switching unit 4111 further includes a first resistor, which is connected in parallel with the first switch. When the solid-state transformer 40 is started, in order to avoid the starting current being too large to cause damage to the devices in the single-phase conversion unit 411, at the starting moment, the first switch can be controlled to be disconnected, and the first resistor can limit the starting current. When the current returns to normal, the first switch is controlled to be closed, and at this moment, the first switch bypasses the first resistor, so as to avoid the energy consumption of the first resistor.

[0072] In order to facilitate understanding, the following gives a specific example of the structure of the first switching unit 4111.

[0073] Referring to Figure 6 Fig. 4 shows a structural schematic diagram of the first switching unit 4111 provided by the embodiment of the application. In Figure 6 , S1 can be regarded as the first switch, and R1 can be regarded as the first resistor.

[0074] Figure 6 The connection relationship of the devices in the first switching unit 4111 shown in Fig. 4 can be that the first electrodes of the switches S1 are respectively connected to the first input end of the single-phase conversion unit 411 and the first end of the first resistor R1, and the second electrodes of the switches S1 and the second electrodes of the first resistors R1 are all connected to the first input end of the voltage conversion unit 4112.

[0075] The first switching unit 4111 provided by the embodiment of the application can be used in the solid-state transformer 40 shown in Fig. 1. Figure 6The first switching unit 4111 is shown. When a certain voltage conversion circuit 41121 in the voltage conversion unit 4112 fails, the voltage conversion unit 4112 sends a driving signal for driving S1 to disconnect to the control electrode of S1. When S1 receives the driving signal, it disconnects the connection between the first electrode and the second electrode. At this time, the failed voltage conversion unit 4112 works in a small current state, thereby avoiding the failure of the unfailed voltage conversion circuit caused by short circuit and other failures, and causing the failure range to increase.

[0076] In an example, in order to prevent the voltage conversion unit 4112 from causing the number of failed devices to increase due to short circuit failure, the power conversion unit 41 further includes a protection unit connected to the first end of the first switching unit 4111. The protection unit can be used for overload protection and short circuit protection. The protection unit can be a mechanical control device, such as a circuit breaker or a fuse. The protection unit can also be an electronic control device, such as an electronic switch tube with a controller.

[0077] Optionally, the protection unit is arranged inside the single-phase conversion unit 411, as shown in Figure 6 As shown, the single-phase conversion unit 411 includes a protection unit 4114. One end of the protection unit 4114 is connected to the first end of the first switch in the first switching unit 4111. At this time, the other end of the protection unit 4114 is the first input end of the single-phase conversion unit 411.

[0078] Optionally, the protection unit is arranged in the power conversion unit 41, and the protection unit is independent of the single-phase conversion unit 411. The protection unit is connected to the first input end of the single-phase conversion unit 411.

[0079] Specifically, the protection unit includes a plurality of protection sub-units. Each protection sub-unit in the plurality of protection sub-units corresponds to each single-phase conversion unit in the plurality of single-phase conversion units. One end of each protection sub-unit is connected to a phase line, and the other end of each protection sub-unit is connected to the first input end of the corresponding single-phase conversion unit, and performs overload protection and short circuit protection on the connected single-phase conversion unit.

[0080] II. Voltage conversion unit 4112

[0081] The first input end of the voltage conversion unit 4112 is connected to the second end of the first switching unit 4111. The second input end of the voltage conversion unit 4112 is connected to the first end of the second switching unit 4113. The output end of the voltage conversion unit 4112 is connected to the output end of the solid-state transformer 40.

[0082] Specifically, as shown in Figure 5 and Figure 6As shown, the voltage conversion unit 4112 includes a plurality of voltage conversion circuits 41121, the input ends of the plurality of voltage conversion circuits 41121 are connected in series, and the output ends of the plurality of voltage conversion circuits 41121 are connected in parallel. The high potential input end of the first voltage conversion circuit 41121 of the plurality of voltage conversion circuits 41121 connected in series constitutes the first input end of the voltage conversion unit 4112, and the low potential input end of the last voltage conversion circuit 41121 of the plurality of voltage conversion circuits 41121 connected in series constitutes the second input end of the voltage conversion unit 4112.

[0083] Referring to Figure 7 As shown, each voltage conversion circuit 41121 can include a first power conversion circuit (a medium voltage side power conversion circuit), a high-frequency transformer, and a second power conversion circuit (a low voltage side power conversion circuit). The first power conversion circuit and the second power conversion circuit can be coupled through the high-frequency transformer. The first power conversion circuit is used to be connected to the medium voltage power grid, and the second power conversion circuit is connected to the load device through the output end of the solid-state transformer 40. It should be noted that the medium voltage and the low voltage only represent two relative concepts, and are not limited to the voltage size. That is, the voltage of the medium voltage side power conversion circuit is greater than the voltage of the low voltage side power conversion circuit.

[0084] In actual application, the first power conversion circuit and the second power conversion circuit in the voltage conversion circuit 41121 can be composed of switching tubes, diodes, inductors, capacitors and the like. The working state of the first power conversion circuit and the second power conversion circuit can be realized by adjusting the working state of these devices (such as switching tubes).

[0085] In this application, the adjustment of the above working state can be realized by a controller. That is, the voltage conversion circuit 41121 can further include a controller, which can be used to control the first power conversion circuit and the second power conversion circuit to perform conversion processing.

[0086] In specific implementation, the controller can be any one of a micro controller unit (MCU), a central processing unit (CPU), and a digital singnal processor (DSP). Of course, the specific form of the controller is not limited to the above examples.

[0087] The voltage conversion unit 4112 provided by the embodiment of the application is connected with the first switching unit 4111 and the second switching unit 4113 respectively, and controls the state of the first switching unit 4111 and the second switching unit 4113.

[0088] In a possible implementation, one of the plurality of voltage conversion circuits 41121 is a target voltage conversion circuit, and the target voltage conversion circuit is connected to the first switching unit 4111 and the second switching unit 4113 respectively.

[0089] In specific use, the target voltage conversion circuit can control the connected first switching unit 4111 and the second switching unit 4113 to be disconnected when any voltage conversion circuit fails, or disconnect the connection between the failed single-phase conversion unit 411 and the connected second switching unit 4113 when any other single-phase conversion unit 411 fails.

[0090] In actual use, since the voltage conversion unit 4112 converts the voltage of the single-phase alternating current transmitted on the connected phase line, there can be a potential difference between the target voltage conversion circuit in the voltage conversion unit 4112 and the first switching unit 4111 and the second switching unit 4113. In order to realize that the target voltage conversion circuit can control the state of the first switching unit 4111 and the second switching unit 4113, a voltage conversion device can be connected to the target voltage conversion circuit to eliminate the potential difference between the target voltage conversion circuit and the first switching unit 4111 and the second switching unit 4113.

[0091] In another example, the voltage conversion unit 4112 includes a first voltage conversion circuit 41121 and a second voltage conversion circuit 41121, the first voltage conversion circuit 41121 is connected to the first switching unit 4111, and the second voltage conversion circuit 41121 is connected to the second switching unit 4113.

[0092] In specific implementation, the first voltage conversion circuit 41121 can control the connected first switching unit 4111 to be disconnected when any voltage conversion circuit 41121 fails. The second voltage conversion circuit 41121 can control the connected second switching unit 4113 to be disconnected when any voltage conversion circuit 41121 fails, or disconnect the connection between the failed single-phase conversion unit 411 and the connected second switching unit 4113 when any other single-phase conversion unit 411 fails.

[0093] In actual use, since the potential of the first voltage conversion circuit 41121 in the plurality of voltage conversion circuits 41121 is the same as the potential of the first switching unit 4111, and the potential of the last voltage conversion circuit 41121 in the plurality of voltage conversion circuits 41121 is the same as the potential of the second switching unit 4113, in order to reduce the control difficulty, the first voltage conversion circuit 41121 can be used as the first voltage conversion circuit 41121, and the last voltage conversion circuit 41121 can be used as the second voltage conversion circuit 41121.

[0094] It should be understood that when the second switching unit 4113 is controlled to be disconnected, the connection between the faulty single-phase conversion unit 411 and the single-phase conversion unit 411 without fault is disconnected, the isolation of the fault source is realized, and it is ensured that the single-phase conversion unit 411 without fault can work normally.

[0095] In a possible implementation, the voltage conversion circuit for controlling the states of the first switching unit 4111 and the second switching unit 4113 in the voltage conversion unit 4112 can detect the fault states of other voltage conversion units in the voltage conversion unit 4112 and the fault states of other single-phase conversion units.

[0096] Specifically, in order to realize that the voltage conversion circuit for controlling the states of the first switching unit 4111 and the second switching unit 4113 can determine the fault states of a plurality of voltage conversion circuits 41121 in the voltage conversion unit 4112, the first transmission channel is connected between the plurality of voltage conversion circuits 41121, and each voltage conversion circuit can determine the fault states of other voltage conversion circuits according to the first transmission channel.

[0097] In actual use, the first transmission channel is connected between the controllers of each voltage conversion circuit.

[0098] In a specific implementation, in order to realize the determination of the fault states of a plurality of single-phase conversion units 411, the second transmission channel is connected between a plurality of single-phase conversion units in each power conversion unit 41, and each single-phase conversion unit 411 can determine the fault states of other single-phase conversion units according to the second transmission channel.

[0099] Based on the above description, referring to FIG. 8, Figure 8 The working process of the target voltage conversion circuit can include the following steps:

[0100] The order of the steps involved in the following does not represent the actual execution order, and therefore the present application does not limit the execution according to the steps and order in the following.

[0101] Step 801: Determine whether there is a faulty voltage conversion circuit in the single-phase conversion unit. If yes, perform step 802; otherwise, return to perform step 803.

[0102] Step 802: Control the first switching unit and the second switching unit to be disconnected, and continue to perform step 803.

[0103] Step 803: Determine whether the connected single-phase conversion unit is faulty. If yes, perform step 804; otherwise, return to perform step 801.

[0104] Step 804: Control the second switching unit to be disconnected from the faulty single-phase conversion unit, and return to perform step 805.

[0105] In step 805, the single-phase conversion unit is in normal operation.

[0106] III. Second switching unit 4113

[0107] The first end of the second switching unit 4113 is connected with the second input end of the voltage conversion unit, the second end of the second switching unit 4113 is the second input end of the single-phase conversion unit 411, and the third end of the second switching unit 4113 is connected with other single-phase conversion units 411.

[0108] In a specific implementation, the second end of the second switching unit 4113 is connected with one single-phase conversion unit 411 of the other single-phase conversion units 411, and the third end of the second switching unit 4113 is connected with another single-phase conversion unit 411 of the other single-phase conversion units 411, so as to realize the connection between the single-phase conversion units.

[0109] The second switching unit 4113 includes a second switch and a third switch. The first electrode of the second switch and the first electrode of the third switch are both connected with the second input end of the voltage conversion unit 4112, the second electrode of the second switch is connected with the second input end of the single-phase conversion unit 411, and the second electrode of the third switch is connected with one single-phase conversion unit 411 of the other single-phase conversion units 411. The second electrode of the second switch is connected with one single-phase conversion unit 411 through the second input end of the single-phase conversion unit 411, and the second electrode of the second switch and the second electrode of the third switch are connected with different single-phase conversion units.

[0110] For ease of understanding, a specific example of the structure of the second switching unit 4113 is given below.

[0111] Referring to Figure 9 FIG. 4 shows a structure diagram of the second switching unit 4113 provided by the embodiment of the present application. In Figure 9 In the structure of the second switching unit 4113 shown in FIG. 4, S2 can be regarded as the second switch, and S3 can be regarded as the third switch.

[0112] Figure 9 The connection relationship of the devices in the second switching unit 4113 shown in FIG. 4 can be that the first electrode of S2 is connected with the low-potential input end of the last voltage conversion circuit in the series-connected multiple voltage conversion circuits, and the second electrode of S2 is connected with the second switching unit of one single-phase conversion unit 411. The first electrode of S3 is connected with the low-potential input end of the last voltage conversion circuit in the series-connected multiple voltage conversion circuits, and the second electrode of S3 is connected with the second switching unit of another single-phase conversion unit 411.

[0113] Taking the three single-phase conversion units 411 in the power conversion unit 41 as an example, each first switching unit 4111 includes two switches S2 and S3, the second electrode of the switch S2 in the single-phase conversion unit 411 receiving the A-phase alternating current is connected to the second electrode of the switch S3 in the single-phase conversion unit 411 receiving the C-phase alternating current, the second electrode of the switch S3 in the single-phase conversion unit 411 receiving the A-phase alternating current is connected to the second electrode of the switch S2 in the single-phase conversion unit 411 receiving the B-phase alternating current, and the second electrode of the switch S3 in the single-phase conversion unit 411 receiving the B-phase alternating current is connected to the second electrode of the switch S2 in the single-phase conversion unit 411 receiving the C-phase alternating current, thereby realizing the connection between all single-phase conversion units in the power conversion unit.

[0114] As shown in FIG. 4, the second switching unit 4113 is configured to send a driving signal for driving the switches S2 and S3 to be disconnected when a certain voltage conversion circuit in the voltage conversion unit 4112 fails. Figure 9 When the switches S2 and S3 in the second switching unit 4113 receive the driving signal, the connection between the first electrode and the second electrode is disconnected, thereby disconnecting the connection between the single-phase conversion unit with failure and the single-phase conversion unit without failure, realizing the isolation of the failure source, and ensuring that the single-phase conversion unit without failure can work normally.

[0115] As shown in FIG. 4, the second switching unit 4113 is configured to send a driving signal for driving the switches S2 and S3 to be disconnected when a certain voltage conversion circuit in the voltage conversion unit 4112 fails. Figure 9 When the switches S2 and S3 in the second switching unit 4113 receive the driving signal, the connection between the first electrode and the second electrode is disconnected, thereby disconnecting the connection between the single-phase conversion unit with failure and the single-phase conversion unit without failure, realizing the isolation of the failure source, and ensuring that the single-phase conversion unit without failure can work normally.

[0116] Based on the same inventive concept, the embodiment of the present application also provides a power supply system, which can include a cabinet and the aforementioned solid-state transformer 400, and the solid-state transformer 400 is arranged in the cabinet.

[0117] The solid-state transformer 400 is connected with a medium-voltage power grid and a load device respectively, and the solid-state transformer 400 can convert and process the electric energy transmitted on the medium-voltage power grid, and output the converted and processed electric energy to the load device. The medium-voltage power grid can be a charging pile or a medium-voltage power grid.

[0118] The solid-state transformer 400 further includes a conductive shell, which can be connected with the cabinet, or the conductive shell can be directly grounded to meet the safety requirements of the solid-state transformer 400.

[0119] Those skilled in the art will appreciate that embodiments of the present application can be devised for a variety of other systems which are currently developed or later developed. Therefore, the present application is intended to cover all such modifications and variations of this application that are within the scope of the appended claims and their equivalents. It is intended that each element of claim 1 and 2 is independent of one another. No element of claim 1 and 2, or any other claim, is implied to depend on any other element or limitation of claim 1 and 2 or any other claim except where expressly recited in that claim.

[0120] The present application is described in reference to the flowchart and / or block diagrams of the method, apparatus (system) and computer program product according to this application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 means for performing each of the functions specified in the flowchart and / or block diagram block or blocks.

[0121] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the function specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 means for performing each of the functions specified in the flowchart and / or block diagram block or blocks.

[0122] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in the flowchart and / or block diagram block or blocks. Figure 1 means for performing each of the functions specified in the flowchart and / or block diagram block or blocks.

[0123] Obviously, numerous modifications and variations of the present application are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A solid state transformer, characterized in that, The power conversion unit comprises a plurality of single-phase conversion units in parallel connection, each single-phase conversion unit comprising a first switching unit, a voltage conversion unit and a second switching unit; The first end of the first switching unit is the first input end of the single-phase conversion unit, and the second end of the first switching unit is connected with the first input end of the voltage conversion unit; the second input end of the voltage conversion unit is connected with the first end of the second switching unit, and the output end of the voltage conversion unit is connected with the output end of the solid-state transformer; the second end of the second switching unit is the second input end of the single-phase conversion unit, and the third end of the second switching unit is connected with one of the other single-phase conversion units in the plurality of single-phase conversion units; The voltage conversion unit comprises a plurality of voltage conversion circuits in series connection, and is configured to control the first switching unit and the second switching unit connected to be disconnected when any voltage conversion circuit fails, or control the second switching unit connected to be disconnected to disconnect the connection with the single-phase conversion unit that fails when the other single-phase conversion unit fails. The voltage conversion circuit comprises a first power conversion circuit, a high-frequency transformer and a second power conversion circuit, and the first power conversion circuit and the second power conversion circuit are coupled through the high-frequency transformer.

2. The solid state transformer of claim 1, wherein, The first switching unit comprises a first switch.

3. The solid state transformer of claim 1, wherein, The first electrode of the first switch constitutes the first end of the first switching unit, and the second electrode of the first switch constitutes the second end of the first switching unit and is connected with the first input end of the voltage conversion unit. The second switching unit comprises a second switch and a third switch.

4. The solid state transformer of any of claims 1-3, wherein, The first electrode of the second switch and the first electrode of the third switch are both connected with the second input end of the voltage conversion unit. The second electrode of the second switch is the second input end of the single-phase conversion unit. The second electrode of the third switch is connected with one of the other single-phase conversion units. The second input end of the single-phase conversion unit is connected with one of the other single-phase conversion units, and the second electrode of the second switch and the second electrode of the third switch are connected with different single-phase conversion units. One of the plurality of voltage conversion circuits is a target voltage conversion circuit, and the target voltage conversion circuit is connected with the first switching unit and the second switching unit respectively.

5. The solid state transformer of any of claims 1-3, wherein, The target voltage conversion circuit is specifically configured to control the first switching unit and the second switching unit connected to be disconnected when any voltage conversion circuit fails, or control the second switching unit connected to be disconnected to disconnect the connection with the single-phase conversion unit that fails when the other single-phase conversion unit fails. The plurality of voltage conversion circuits comprises a first voltage conversion circuit and a second voltage conversion circuit.

6. The solid state transformer of any of claims 1-3, wherein, The first voltage conversion circuit is connected with the first switching unit. The second voltage conversion circuit is connected with the second switching unit. The first voltage conversion circuit is configured to control the first switching unit connected to be disconnected when any voltage conversion circuit fails. ​ The second voltage conversion circuit is configured to: control the connected second switching unit to be disconnected when any voltage conversion circuit fails; or disconnect the connection with the failed single-phase conversion unit through the connected second switching unit when the other single-phase conversion unit fails.

7. The solid state transformer of claim 3, wherein, The power conversion unit further comprises a protection unit connected to the first end of the first switching unit.

8. The solid state transformer of claim 5, wherein, The controllers in the plurality of voltage conversion circuits have a first transmission channel, and each voltage conversion circuit determines the failure state of the other voltage conversion circuits according to the first transmission channel.

9. The solid state transformer of claim 5, wherein, The plurality of single-phase conversion units have a second transmission channel, and each single-phase conversion unit determines the failure state of the other single-phase conversion units according to the second transmission channel.

10. A power supply device, characterized by comprising: A cabinet and a solid-state transformer as claimed in any one of claims 1-9 are included, and the solid-state transformer is arranged in the cabinet.

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