Power conversion unit and power electronic transformer

Abstract

The utility model discloses a power conversion unit and a power electronic transformer, the power conversion unit comprises a control circuit, a first change-over switch, a power circuit, a first charging and discharging unit and a plug-in assembly, and the plug-in assembly comprises a first straight-through pin, a second straight-through pin and a third straight-through pin; because the first change-over switch can connect or disconnect the access between the input power supply and the input end of the power circuit, and the plug-in assembly comprises the charging and discharging station and the normal working station, when the plug-in assembly is in the charging and discharging station, the output capacitor in the power circuit is charged or discharged through the first charging and discharging unit; when the plugging assembly is in a normal working station, the input capacitor of the power circuit is charged or discharged through the output capacitor, so that hot plugging of the power conversion unit is realized, and when the power conversion unit fails, the power conversion unit can be hot-plugged, so that the failed power conversion unit can be replaced on line, and the power conversion efficiency is improved. And the performance and the reliability of the power electronic transformer are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of power supplies, and particularly relates to a power conversion unit and a power electronic transformer. Background Art

[0002] A power electronic transformer (also known as a solid-state transformer or an electric energy router) is a new type of power conversion device, which has the advantages of high efficiency, light weight, low noise, high stability, etc., and is widely used in fields such as data centers and AC-DC microgrids.

[0003] Currently, the power electronic transformer usually adopts an ISOP-type system architecture, that is, the power electronic transformer includes a plurality of power conversion units, the input ends of the plurality of power conversion units are cascaded to form the input end of the power electronic transformer, the output ends of the plurality of power conversion units are connected in parallel to form the output end of the power electronic transformer, the input end of the power electronic transformer can be medium-voltage alternating current or medium-voltage direct current, and the output end of the power electronic transformer can be low-voltage alternating current or low-voltage direct current.

[0004] When a power conversion unit in the power electronic transformer fails, the power conversion unit is usually cut out from the power electronic transformer by a bypass mode, and the remaining other power conversion units continue to work.

[0005] In the related art, bypassing the faulty power conversion unit from the power electronic transformer will reduce the performance and reliability of the power electronic transformer. Summary of the Utility Model

[0006] The utility model provides a power conversion unit and a power electronic transformer to solve the problem that the performance and reliability of the power electronic transformer are affected when the power conversion unit fails in the prior art.

[0007] In a first aspect, the present application provides a power conversion unit, including: a control circuit, a first switching switch, a power circuit, a first charge and discharge unit, and a plug-in component, wherein the plug-in component includes a first through-pin, a second through-pin, and a third through-pin;

[0008] The control circuit is electrically connected to the control end of the power circuit, the first switching switch is connected between the input power supply and the input end of the power circuit, the first charge and discharge unit is connected between the first output end of the power circuit and the first through-pin, the first output end of the power circuit is electrically connected to the second through-pin, and the second output end of the power circuit is electrically connected to the third through-pin;

[0009] The plug-in component includes a charging and discharging station and a normal working station. When the plug-in component is at the charging and discharging station, the first through-pin is in an electrically connected state with the first terminal of the output power supply, the second through-pin is in a disconnected state from the first terminal of the output power supply, and the third through-pin is in an electrically connected state with the second terminal of the output power supply. When the plug-in component is at the normal working station, the first through-pin is in an electrically connected state with the first terminal of the output power supply, the second through-pin is in an electrically connected state with the first terminal of the output power supply, and the third through-pin is in an electrically connected state with the second terminal of the output power supply.

[0010] The power conversion unit provided by the embodiment of the present application includes: a control circuit, a first switching switch, a power circuit, a first charging and discharging unit, and a plug-in component. Among them, the plug-in component includes a first through-pin, a second through-pin, and a third through-pin. Since the first switching switch can conduct or disconnect the path between the input power supply and the input terminal of the power circuit, and the plug-in component includes a charging and discharging station and a normal working station. When the plug-in component is at the charging and discharging station, the output capacitor in the power circuit is charged or discharged through the first charging and discharging unit. When the plug-in component is at the normal working station, the input capacitor in the power circuit is charged or discharged through the output capacitor, so as to realize the hot plugging of the power conversion unit without power-off, replace the faulty power conversion unit, and thus improve the performance and reliability of the power electronic transformer.

[0011] In a possible implementation manner, the length of the first through-pin is greater than the length of the second through-pin.

[0012] In the above solution, the length of the first through-pin is greater than the length of the second through-pin, so that when the plug-in component is at the charging and discharging station, the first through-pin is in an electrically connected state with the first terminal of the output power supply, and the second through-pin is in a disconnected state from the first terminal of the output power supply, thereby realizing the hot plugging of the power conversion unit.

[0013] In a possible implementation manner, a second charging and discharging unit is further included, and the plug-in component further includes a fourth through-pin;

[0014] The second charging and discharging unit is connected between the second output terminal of the power circuit and the fourth through-pin;

[0015] When the plug-in component is at the charging and discharging station, the third through-pin is in a disconnected state from the second terminal of the output power supply, and the fourth through-pin is in an electrically connected state with the second terminal of the output power supply. When the plug-in component is at the normal working station, the third through-pin is in an electrically connected state with the second terminal of the output power supply, and the fourth through-pin is in an electrically connected state with the second terminal of the output power supply.

[0016] In the above solution, a fourth through-pin is added to the plug-in component. When the plug-in component is in the charging and discharging station, both the first through-pin and the second through-pin are electrically connected to the DC bus on the load side. When charging or discharging the output capacitor, a charging and discharging resistor is connected to both the positive DC bus on the load side and the negative DC bus on the load side, thereby improving the charging or discharging efficiency.

[0017] In a possible implementation, the length of the fourth through-pin is greater than the length of the third through-pin.

[0018] In the above solution, the length of the fourth through-pin is greater than the length of the third through-pin, so that when the plug-in component is in the charging and discharging station, the fourth through-pin is in an electrically connected state with the second end of the output power supply, and the third through-pin is in a disconnected state from the second end of the output power supply, thereby realizing the hot plugging of the power conversion unit.

[0019] In a possible implementation, the first charging and discharging unit includes at least one first resistor;

[0020] If the first charging and discharging unit includes a plurality of first resistors, the plurality of first resistors are connected in series or in parallel.

[0021] In a possible implementation, the second charging and discharging unit includes at least one second resistor;

[0022] If the second charging and discharging unit includes a plurality of second resistors, the plurality of second resistors are connected in series or in parallel.

[0023] In the above solution, both the first charging and discharging unit and the second charging and discharging unit include one resistor or a plurality of resistors. If a plurality of resistors are included, the plurality of resistors are connected in series or in parallel, thereby improving the charging and discharging efficiency.

[0024] In a possible implementation, the first switching switch includes a contactor;

[0025] The first normally open contact of the contactor and the first normally closed contact of the contactor are electrically connected to the first end of the input power supply. The second normally open contact of the contactor is electrically connected to the first input end of the power circuit. The second normally closed contact of the contactor is electrically connected to the second end of the input power supply and the second input end of the power circuit.

[0026] In the above solution, a contactor is used to realize the opening or closing of the path between the input power supply and the power circuit. When the power conversion unit fails, the path between the input power supply and the power circuit is opened, and the input end of the power circuit is short-circuited, thereby providing plugging conditions for the hot plugging of the faulty power conversion unit.

[0027] In a possible implementation, the power circuit includes an input capacitor, an output capacitor, and a DC-DC conversion unit;

[0028] The first end of the input capacitor is electrically connected to the first input end of the DC-DC conversion unit and serves as the first input end of the power circuit, and the second end of the input capacitor and the second input end of the DC-DC conversion unit serve as the second input end of the power circuit;

[0029] The first end of the output capacitor is electrically connected to the first output end of the DC-DC conversion unit and serves as the first output end of the power circuit, and the second end of the output capacitor is electrically connected to the second output end of the DC-DC conversion unit and serves as the second output end of the power circuit.

[0030] In the above solution, the DC-DC conversion unit adopts a bidirectional DC-DC circuit, so as to discharge the input capacitor and the output capacitor in the faulty power conversion unit, charge the input capacitor and the output capacitor in the power conversion unit with good performance, and then realize the hot plug of the power conversion unit, improving the performance and reliability of the power electronic transformer.

[0031] In a possible implementation, the power circuit further includes a rectification unit;

[0032] The rectification unit is connected between the first switching switch and the input capacitor;

[0033] The rectification unit is used to convert the input alternating current into direct current.

[0034] In the above solution, when the input end is alternating current, the rectification unit converts the alternating current to obtain direct current, so that the power conversion unit realizes the conversion between direct currents.

[0035] In a possible implementation, the control circuit includes a first auxiliary power supply and a second auxiliary power supply;

[0036] The input end of the first auxiliary power supply is electrically connected to both ends of the input capacitor, and the output end of the first auxiliary power supply is electrically connected to the power supply end of the control circuit;

[0037] The input end of the second auxiliary power supply is electrically connected to both ends of the output capacitor, and the output end of the second auxiliary power supply is electrically connected to the power supply end of the control circuit;

[0038] Both the first auxiliary power supply and the second auxiliary power supply are used to supply power to the control circuit.

[0039] In the above solution, the control circuit is powered by the voltage pooled from the first auxiliary power supply and the second auxiliary power supply. Since the input capacitor supplies power to the first auxiliary power supply and the output capacitor supplies power to the second auxiliary power supply, it can ensure continuous power supply to the control circuit when the input capacitor is out of power and the output capacitor is powered, or when the input capacitor is powered and the output capacitor is out of power, improving the continuity of power supply and thus enhancing the performance of the control circuit.

[0040] In a possible implementation, the control circuit includes a third auxiliary power supply and a second switching switch;

[0041] The first terminal of the second switching switch is electrically connected to the first terminal of the input capacitor, the second terminal of the second switching switch is electrically connected to the first terminal of the output capacitor, the third terminal of the second switching switch is electrically connected to the first input terminal of the third auxiliary power supply, and the second terminals of the input capacitor and the output capacitor are electrically connected to the second input terminal of the third auxiliary power supply;

[0042] The second switching switch is configured to conduct the path between the input capacitor and the third auxiliary power supply and disconnect the path between the output capacitor and the third auxiliary power supply, or disconnect the path between the input capacitor and the third auxiliary power supply and conduct the path between the output capacitor and the third auxiliary power supply.

[0043] In the above solution, using one auxiliary power supply to power the control terminal circuit can reduce the complexity of power supply. By using the second switching switch and powering with the input capacitor or the output capacitor, the continuity of power supply is improved, and thus the performance of the control circuit is enhanced.

[0044] In a possible implementation, the second switching switch includes a single-pole double-throw switch;

[0045] The first fixed terminal of the single-pole double-throw switch is electrically connected to the first terminal of the input capacitor, the second fixed terminal of the single-pole double-throw switch is electrically connected to the first terminal of the output capacitor, and the moving terminal of the single-pole double-throw switch is electrically connected to the first input terminal of the auxiliary power supply.

[0046] In the above solution, using a single-pole double-throw switch to control power supply through the input capacitor or the output capacitor improves the simplicity of switching.

[0047] In a second aspect, the present application further provides a power electronic transformer, including a plurality of power conversion units as described in any one of the first aspect.

[0048] In addition, the technical effects brought by any implementation manner in the second aspect can refer to the technical effects brought by different implementation manners in the first aspect, which will not be elaborated here. Description of the Drawings

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0050] Figure 1 A schematic structural diagram of a power electronic transformer provided by the related art;

[0051] Figure 2 A schematic structural diagram of a power conversion unit provided by an embodiment of the present application;

[0052] Figure 3 Another schematic structural diagram of a power conversion unit provided by an embodiment of the present application;

[0053] Figure 4 Another schematic structural diagram of a power conversion unit provided by an embodiment of the present application;

[0054] Figure 5 Another schematic structural diagram of a power conversion unit provided by an embodiment of the present application;

[0055] Figure 6 Another schematic structural diagram of a power conversion unit provided by an embodiment of the present application;

[0056] Figure 7 Another schematic structural diagram of a power conversion unit provided by an embodiment of the present application;

[0057] Figure 8 A schematic structural diagram of a structure for providing electrical energy to an auxiliary power supply provided by an embodiment of the present application;

[0058] Figure 9 Another schematic structural diagram of a structure for providing electrical energy to an auxiliary power supply provided by an embodiment of the present application;

[0059] Figure 10 A schematic flow chart of a hot plugging method provided by an embodiment of the present application;

[0060] Figure 11 A schematic diagram of a power conversion unit not being plugged in place provided by an embodiment of the present application;

[0061] Figure 12 A schematic diagram of a power conversion unit being plugged in place provided by an embodiment of the present application;

[0062] Figure 13 Another schematic flow chart of a hot plugging method provided by an embodiment of the present application;

[0063] Figure 14 Schematic diagram of a power conversion unit not inserted in place provided by an embodiment of the present application;

[0064] Figure 15 Schematic diagram of a power conversion unit inserted in place provided by an embodiment of the present application;

[0065] Figure 16 Schematic diagram of the structure of a power electronic transformer provided by an embodiment of the present application. Detailed implementation manners

[0066] In order to make the objectives, technical solutions and advantages of the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings. Apparently, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0067] As Figure 1 shown, it is a schematic diagram of the structure of a power electronic transformer provided by an embodiment of the present application. The power electronic transformer includes N power conversion units. The input ends of each power conversion unit are cascaded to form the input end of the power electronic transformer, which is connected to the medium-voltage distribution bus. The output ends of each power conversion unit are connected in parallel to form the output end of the power electronic transformer, which is connected to the low-voltage distribution bus. Wherein, N is a positive integer greater than or equal to 2.

[0068] If a certain power conversion unit in the power electronic transformer fails, the faulty power conversion unit is bypassed from the power electronic transformer, and the remaining power conversion units continue to work. It is impossible to perform on-line maintenance of the faulty power conversion unit without power interruption. Higher reliability of the power electronic transformer depends on greater redundancy, resulting in a large volume and increased cost of the power electronic transformer. At the same time, due to the low load rate, the overall system efficiency is not high, and it cannot completely ensure the continuous operation of the power electronic transformer, thus reducing the performance and reliability of the power electronic transformer.

[0069] To solve the above technical problems, an embodiment of the present application provides a power conversion unit. The power conversion unit can achieve on-line real-time replacement of the power conversion unit through hot plugging. When a single power conversion unit fails, it is removed from the power electronic transformer, and then a power conversion unit with good performance is replaced at the original position, thereby improving the performance and reliability of the power electronic transformer and keeping the powered services uninterrupted. The power conversion unit provided by the embodiment of the present application will be described in detail below.

[0070] As Figure 2As shown in the figure, it is a schematic structural diagram of a power conversion unit provided by an embodiment of the present application. The power conversion unit includes: a control circuit (not shown in Figure 2 ), a first switching switch 21, a power circuit 22, a first charge and discharge unit 23, and a plug-in component 24. Among them, the plug-in component 24 includes a first through-pin 241, a second through-pin 242, and a third through-pin 243;

[0071] The control circuit is electrically connected to the control end of the power circuit 22. The first switching switch 21 is connected between the input power supply Ui and the input end of the power circuit 22. The first charge and discharge unit 23 is connected between the first output end of the power circuit 22 and the first through-pin 241. The first output end of the power circuit 22 is electrically connected to the second through-pin 242, and the second output end of the power circuit 22 is electrically connected to the third through-pin 243;

[0072] The plug-in component 24 includes a charge and discharge working position and a normal working position. When the plug-in component 24 is in the charge and discharge working position, the first through-pin 241 is in an electrically connected state with the first end of the output power supply, the second through-pin 242 is in a disconnected state from the first end of the output power supply, and the third through-pin 243 is in an electrically connected state with the second end of the output power supply; when the plug-in component 24 is in the normal working position, the first through-pin 241 is in an electrically connected state with the first end of the output power supply, the second through-pin 242 is in an electrically connected state with the first end of the output power supply, and the third through-pin 243 is in an electrically connected state with the second end of the output power supply.

[0073] For the power conversion unit provided by the embodiment of the present application, the first switching switch is used to conduct or disconnect the path between the input power supply and the input end of the power circuit. When the power conversion unit is normal, the first switching switch conducts the path between the input power supply and the power circuit, and the plug-in component is in the normal working position. When the plug-in component is in the normal working position, both the first through-pin and the second through-pin are electrically connected to the first end of the output power supply. At this time, the first charge and discharge unit is short-circuited, and the power conversion unit works normally; when the power conversion unit fails, the first switching switch disconnects the path between the input power supply and the power circuit, and the staff pulls out the power conversion unit from the power electronic transformer. At this time, the plug-in component is in the charge and discharge working position. The first output end of the power circuit is disconnected from the first end of the output power supply through the second through-pin, and is electrically connected to the first end of the output power supply through the first charge and discharge unit and the first through-pin. The second output end of the power circuit is electrically connected to the second end of the output power supply through the third through-pin, thereby forming a discharge loop, and the output capacitor in the power circuit discharges through the first charge and discharge unit;

[0074] After the waiting output capacitor finishes discharging, the staff continues to pull out the power conversion unit from the power electronic transformer. At this time, the first through-pin is disconnected from the first terminal of the output power supply, and the third through-pin is disconnected from the second terminal of the output power supply. That is, the power conversion unit is completely detached from the power electronic transformer. The input capacitor in the power circuit forms a discharge loop through the output capacitor to discharge the input capacitor until the electricity in the input capacitor is completely discharged;

[0075] After pulling out the faulty power conversion unit from the power electronic transformer, the staff inserts a power conversion unit with good performance at this position. First, insert the power conversion unit into the power electronic transformer. At this time, the plugging and unplugging assembly is in the charging and discharging working position. The first output terminal of the power circuit is electrically connected to the first terminal of the output power supply through the first charging and discharging unit and the first through-pin, and the second output terminal of the power circuit is electrically connected to the second terminal of the output power supply through the third through-pin, thereby forming a charging loop. The output capacitor in the power circuit is charged through the first charging and discharging unit;

[0076] After the charging is completed, the staff continues to insert the power conversion unit into the power electronic transformer. At this time, the plugging and unplugging assembly is in the normal working position. The first output terminal of the power circuit is electrically connected to the first terminal of the output power supply through the first charging and discharging unit and the first through-pin, and is also electrically connected to the first terminal of the output power supply through the second through-pin. The second output terminal of the power circuit is electrically connected to the second terminal of the output power supply through the third through-pin. At this time, the first charging and discharging unit is short-circuited. The output capacitor in the power circuit forms a charging loop with the input capacitor in the power circuit to charge the input capacitor. After the input capacitor finishes charging, the first switching switch conducts the path between the input power supply and the power circuit, thereby connecting the power conversion unit to the power electronic transformer.

[0077] The above process realizes the hot plugging and unplugging of the power conversion unit. Compared with bypassing the faulty power conversion unit, it can improve the performance and reliability of the power electronic transformer.

[0078] In the embodiment of the present application, the first switching switch 21 can be controlled by a control circuit. When the control circuit detects a fault in the power conversion unit, such as a short-circuit phenomenon or an open-circuit phenomenon, the control circuit controls the first switching switch 21 to disconnect the path between the input power supply Ui and the power circuit 22. When inserting the power conversion unit into the power electronic transformer, when the control circuit detects that the input capacitor C1 has finished charging, it controls the first switching switch 21 to conduct the path between the input power supply Ui and the power circuit 22.

[0079] The output power supply in the embodiment of the present application can be the positive DC bus on the load side and the negative DC bus on the load side, and the plugging and unplugging assembly 24 can be a connector.

[0080] The control circuit may include an IGBT drive circuit, a DSP, a CPLD, etc.

[0081] In a specific implementation, such as Figure 2 shown, the length of the first through-pin 241 is greater than the length of the second through-pin 242.

[0082] In the embodiment of the present application, since the length of the first through-pin 241 is greater than the length of the second through-pin 242, the charging and discharging station and the normal working station of the plug-in component can be realized.

[0083] Such as Figure 3 shown, the power conversion unit provided by the embodiment of the present application may further include a second charging and discharging unit 31, and the plug-in component 24 further includes a fourth through-pin 244;

[0084] The second charging and discharging unit 31 is connected between the second output terminal of the power circuit 22 and the fourth through-pin 244;

[0085] When the plug-in component 24 is in the charging and discharging station, the third through-pin 243 is in a disconnected state from the second terminal of the output power supply, and the fourth through-pin 244 is in an electrically connected state with the second terminal of the output power supply. When the plug-in component 24 is in the normal working station, the third through-pin 243 is in an electrically connected state with the second terminal of the output power supply, and the fourth through-pin 244 is in an electrically connected state with the second terminal of the output power supply.

[0086] In a specific implementation, the length of the fourth through-pin 244 is greater than the length of the third through-pin 243.

[0087] In the embodiment of the present application, when the power conversion unit fails, the staff pulls out the power conversion unit from the power electronic transformer. At this time, the plug-in component is in the charging and discharging station. The first output terminal of the power circuit is electrically connected to the first terminal of the output power supply through the first charging and discharging unit and the first through-pin, and is disconnected from the first terminal of the output power supply through the second through-pin. The second output terminal of the power circuit is electrically connected to the second terminal of the output power supply through the second charging and discharging unit and the fourth through-pin, and is disconnected from the second terminal of the output capacitor through the third through-pin, thereby forming a discharge loop. The output capacitor in the power circuit discharges through the first charging and discharging unit and the second charging and discharging unit;

[0088] After the output capacitor finishes discharging, the staff continues to pull out the power conversion unit from the power electronic transformer. At this time, the first through-pin is disconnected from the first terminal of the output power supply, and the fourth through-pin is disconnected from the second terminal of the output power supply. The input capacitor in the power circuit forms a discharge loop through the output capacitor to discharge the input capacitor until the electricity in the input capacitor is completely discharged;

[0089] After pulling out the faulty power conversion unit from the power electronic transformer, the staff inserts a power conversion unit with good performance at this position. First, insert the power conversion unit into the power electronic transformer. At this time, the plugging and unplugging assembly is in the charging and discharging working position. The first output end of the power circuit is electrically connected to the first end of the output power supply through the first charging and discharging unit and the first through-pin. The second output end of the power circuit is electrically connected to the second end of the output power supply through the second charging and discharging unit and the fourth through-pin, thus forming a charging circuit. The output capacitor in the power circuit is charged through the first charging and discharging unit and the second charging and discharging unit.

[0090] After the charging is completed, the staff continues to insert the power conversion unit into the power electronic transformer. At this time, the plugging and unplugging assembly is in the normal working position. The first output end of the power circuit is electrically connected to the first end of the output power supply through the first charging and discharging unit and the first through-pin. The first output end of the power circuit is electrically connected to the first end of the output power supply through the second through-pin. The second output end of the power circuit is electrically connected to the second end of the output power supply through the second charging and discharging unit and the fourth through-pin. The second output end of the power circuit is electrically connected to the second end of the output power supply through the third through-pin. At this time, both the first charging and discharging unit and the second charging and discharging unit are short-circuited. The output capacitor in the power circuit and the input capacitor in the power circuit form a charging circuit to charge the input capacitor. After the input capacitor is charged, the first switching switch conducts the path between the input power supply and the power circuit, thereby realizing the access of the power conversion unit to the power electronic transformer.

[0091] In one embodiment, the first charging and discharging unit 23 includes at least one first resistor;

[0092] If the first charging and discharging unit includes multiple first resistors, the multiple first resistors are connected in series or in parallel.

[0093] As Figure 3 shown, the first charging and discharging unit 23 includes a first resistor R1, and the first resistor R1 is connected between the first output end of the power circuit and the first through-pin 241.

[0094] As Figure 4 shown, the first charging and discharging unit 23 includes multiple first resistors R1. After the multiple first resistors R1 are connected in parallel, they are connected between the first output end of the power circuit and the first through-pin 241.

[0095] As Figure 5 shown, the first charging and discharging unit 23 includes multiple first resistors R1. After the multiple first resistors R1 are connected in series, they are connected between the first output end of the power circuit and the first through-pin 241.

[0096] In one embodiment, the second charging and discharging unit 31 includes at least one second resistor;

[0097] If the second charge and discharge unit includes a plurality of second resistors, the plurality of second resistors are connected in series or in parallel.

[0098] As Figure 3 shown in the figure, the second charge and discharge unit 31 includes a second resistor R2, and the second resistor R2 is connected between the second output terminal of the power circuit and the fourth through pin 244.

[0099] As Figure 4 shown in the figure, the second charge and discharge unit 31 includes a plurality of second resistors R2. After the plurality of second resistors R2 are connected in parallel, they are connected between the second output terminal of the power circuit and the fourth through pin 244.

[0100] As Figure 5 shown in the figure, the second charge and discharge unit 31 includes a plurality of second resistors R2. After the plurality of second resistors R2 are connected in series, they are connected between the second output terminal of the power circuit and the fourth through pin 244.

[0101] In the embodiments of the present application, the charge and discharge unit adopts a plurality of resistors connected in series or in parallel, which can improve the efficiency of charging or discharging.

[0102] In one embodiment, as Figure 6 shown in the figure, the first switching switch 21 includes a contactor K1;

[0103] The first normally open contact and the first normally closed contact of the contactor K1 are electrically connected to the first end of the input power supply. The second normally open contact of the contactor K1 is electrically connected to the first input end of the power circuit. The second normally closed contact of the contactor K1 is electrically connected to the second end of the input power supply and the second input end of the power circuit.

[0104] In the embodiments of the present application, when the power conversion unit is working normally, the control circuit supplies electrical energy to the coil of the contactor K1. The first normally open contact and the second normally open contact of the contactor K1 are turned on, and the path between the input power supply and the power circuit is turned on. When the control circuit detects that a fault occurs in the power conversion unit, it stops supplying electrical energy to the coil of the contactor K1. The path between the first normally open contact and the second normally open contact of the contactor K1 is disconnected, and the path between the first normally closed contact and the second normally closed contact is turned on. The contactor K1 disconnects the path between the input power supply and the power circuit;

[0105] When inserting a power conversion unit with good performance, after the control circuit detects that the input capacitor C1 is fully charged, it supplies electrical energy to the coil of the contactor K1, and the two normally open contacts of the contactor K1 are closed, and the power conversion unit is connected to the power electronic transformer.

[0106] It should be noted that when the coil of the contactor K1 loses power, the main contact of the contactor K1 is located between the first normally closed contact and the second normally closed contact of the contactor K1, that isFigure 6 At the NC position in , when the coil of contactor K1 is energized, the main contacts of contactor K1 switch from the first normally closed contact and the second normally closed contact to the first normally open contact and the second normally open contact, and the first normally open contact and the second normally open contact are Figure 6 At the NO position in . When the main contacts are at the first normally closed contact and the second normally closed contact, the first normally closed contact and the second normally closed contact are connected. When the main contacts are at the first normally open contact and the second normally open contact, the first normally open contact and the second normally open contact are connected.

[0107] In addition, two normally closed contacts of contactor K1 are connected, disconnecting the path between the input power supply and the input end of the power circuit, which is equivalent to short - circuiting the input end of the power circuit.

[0108] In implementation, the power electronic transformer can convert direct current to direct current, or convert direct current to alternating current, or convert alternating current to direct current, or convert alternating current to alternating current.

[0109] Figures 2 to 6 The power conversion units shown are all power conversion units corresponding to power electronic transformers with direct current input and direct current output. When it comes to the power conversion unit corresponding to a power electronic transformer with direct current input and alternating current output, at Figures 2 to 5 On the other side of the DC bus on the load side of any one of the power conversion units shown, an inverter unit is added. The inverter unit converts the direct current on the load - side DC bus into alternating current, thus realizing the power conversion unit that constitutes a power electronic transformer for converting direct current to alternating current.

[0110] The implementation of the inverter unit can refer to the inverter unit provided by related technologies and will not be elaborated here.

[0111] As Figures 2 to 6 shown, the power circuit 22 includes an input capacitor C1, an output capacitor C2, and a DC - DC conversion unit 221;

[0112] The input capacitor C1 is connected between the first switching switch 21 and the DC - DC conversion unit 221. The DC - DC conversion unit 221 is connected between the input capacitor C1 and the output capacitor C2. The first end of the output capacitor C2 is also electrically connected to the first charge - discharge unit 23, and the second end of the output capacitor C2 is also electrically connected to the second charge - discharge unit 31.

[0113] When the input power supply is alternating current, a rectification unit needs to be added to the power circuit. The rectification unit is connected between the first switching switch 21 and the input capacitor C1, and is used to convert the input alternating current into direct current and then input the converted direct current into the DC - DC conversion unit 221.

[0114] Specifically, as Figure 7 shown, the power circuit includes a rectification circuit 71, an input capacitor C1, a DC-DC conversion circuit 221, and an output capacitor C2;

[0115] The rectification unit 71 is connected between the first switching switch 21 and the input capacitor C1. The input capacitor C1 is connected between the rectification unit 71 and the DC-DC conversion unit 221. The DC-DC conversion unit 221 is connected between the input capacitor C1 and the output capacitor C2. The first end of the output capacitor C2 is also electrically connected to the first charge and discharge unit 23, and the second end of the output capacitor C2 is also electrically connected to the second charge and discharge unit 31.

[0116] Figure 7 The power conversion unit shown converts alternating current into direct current. If alternating current is to be converted into alternating current, an inverter unit is usually added on the other side of the DC bus on the load side. The implementation of the inverter unit can refer to the inverter unit provided by the related technology and will not be elaborated here.

[0117] In a specific implementation, the DC-DC conversion unit is a bidirectional DC-DC circuit, such as a DAB circuit, that is, a bidirectional active bridge DC-DC converter.

[0118] As Figures 2 to 7 shown, the DC-DC conversion unit 221 in the embodiment of the present application includes a first switching transistor T1, a second switching transistor T2, a third switching transistor T3, a fourth switching transistor T4, a fifth switching transistor T5, a sixth switching transistor T6, a seventh switching transistor T8, an inductor L, and a transformer T. The control terminals of the switching transistors are all electrically connected to the control circuit, and each switching transistor is controlled by the control circuit to conduct and turn off, so as to realize the charging and discharging of the input capacitor C1 and the output capacitor C2.

[0119] As Figure 7 shown, the rectification unit 71 in the power conversion unit provided by the embodiment of the present application includes a ninth switching transistor T9, a tenth switching transistor T10, an eleventh switching transistor T11, and a twelfth switching transistor T12. The control terminals of each switching transistor are also electrically connected to the control circuit, and each switching transistor is controlled by the control circuit to conduct and turn off, so as to realize the conversion of alternating current into direct current.

[0120] The DC-DC conversion unit in the embodiment of the present application can be an isolated DC-DC conversion unit or a non-isolated DC-DC conversion unit.

[0121] As Figures 2 to 7 shown, it is a schematic structural diagram of an isolated DC-DC conversion unit.

[0122] In a specific implementation, the control circuit may include a first auxiliary power supply and a second auxiliary power supply, as Figure 8 shown;

[0123] The input terminal of the first auxiliary power supply 81 is electrically connected to both ends of the input capacitor C1, and the output terminal of the first auxiliary power supply 81 is electrically connected to the power supply terminal of the control circuit;

[0124] The input terminal of the second auxiliary power supply 82 is electrically connected to both ends of the output capacitor C2, and the output terminal of the second auxiliary power supply 82 is electrically connected to the power supply terminal of the control circuit;

[0125] Both the first auxiliary power supply 81 and the second auxiliary power supply 82 are used to supply power to the control circuit.

[0126] In the embodiment of the present application, the input capacitor C1 supplies power to the first auxiliary power supply 81, the output capacitor C2 supplies power to the second auxiliary power supply 82, and the voltage after the convergence of the two auxiliary power supplies is used to supply power to the control circuit, which can improve the continuity of power supply and the performance of the control circuit.

[0127] In another embodiment, as Figure 9 shown, the control circuit includes a second switching switch 81 and a third auxiliary power supply 82;

[0128] The first terminal of the second switching switch 81 is electrically connected to the first terminal of the input capacitor C1, the second terminal of the second switching switch 81 is electrically connected to the first terminal of the output capacitor C2, the third terminal of the second switching switch 81 is electrically connected to the first input terminal of the third auxiliary power supply 82, and the second terminals of the input capacitor C1 and the output capacitor C2 are electrically connected to the second input terminal of the third auxiliary power supply 82;

[0129] The output terminal of the third auxiliary power supply 82 is electrically connected to the power supply terminal of the control circuit;

[0130] The second switching switch 81 is used to conduct the path between the input capacitor C1 and the third auxiliary power supply 82 and disconnect the path between the output capacitor C2 and the third auxiliary power supply 82, or disconnect the path between the input capacitor C1 and the third auxiliary power supply 82 and conduct the path between the output capacitor C2 and the third auxiliary power supply 82;

[0131] The third auxiliary power supply 82 is used to supply power to the control circuit.

[0132] Specifically, the second switching switch 81 includes a single-pole double-throw switch K2;

[0133] The first fixed terminal of the single-pole double-throw switch K2 is electrically connected to the first terminal of the input capacitor C1, the second fixed terminal of the single-pole double-throw switch K2 is electrically connected to the first terminal of the output capacitor C2, and the moving terminal of the single-pole double-throw switch K2 is electrically connected to the first input terminal of the third auxiliary power supply 82.

[0134] In a specific implementation, the single-pole double-throw switch K2 can be controlled by a control circuit. When the input capacitor C1 is powered, the control unit can control the first fixed terminal and the moving terminal of the single-pole double-throw switch K2 to be connected to supply power using the input capacitor C1. When the output capacitor C2 is powered, the control unit can control the second fixed terminal and the moving terminal of the single-pole double-throw switch K2 to be connected to supply power using the output capacitor C2. When both the input capacitor C1 and the input capacitor C2 are powered, the control circuit can control the first fixed terminal and the moving terminal of the single-pole double-throw switch K2 to be connected, or can also control the second fixed terminal and the moving terminal of the single-pole double-throw switch K2 to be connected.

[0135] In the embodiment of the present application, a single-pole double-throw switch is used to control the input capacitor C1 or the output capacitor C2 to supply power to the control circuit, which can improve the continuity of power supply and the performance of the control circuit.

[0136] The power conversion unit provided by the embodiment of the present application can achieve hot plugging. For the convenience of understanding, the following will be described with specific embodiments.

[0137] As Figure 10 shown, it is a schematic flow chart of a hot plugging method provided by the embodiment of the present application, which specifically includes the following steps:

[0138] S1001. The control unit determines that a certain power conversion unit in the power electronic converter is faulty;

[0139] S1002. The control unit stops supplying power to the coil of the contactor in the power conversion unit, and the main contact of the contactor switches from NO to NC;

[0140] S1003. The staff pulls out the power conversion unit to the charge and discharge station of the plug-in assembly;

[0141] As Figure 11 shown, when the plug-in assembly is at the charge and discharge station, the first through-pin is electrically connected to the positive DC bus on the load side, the second through-pin is disconnected from the positive DC bus on the load side, the third through-pin is disconnected from the negative DC bus on the load side, the fourth through-pin is electrically connected to the negative DC bus on the load side, and the output capacitor C2 discharges.

[0142] S1004. The output capacitor discharges through the first charge and discharge unit and the second charge and discharge unit;

[0143] S1005. After the output capacitor finishes discharging, the control unit starts the DC-DC conversion unit to enable the input capacitor to form a discharge loop through the DC-DC conversion unit and the output capacitor, and at the same time, the staff pulls out the power conversion unit from the slot;

[0144] As Figure 12As shown, both the first through-pin and the second through-pin are disconnected from the positive DC bus on the load side, and both the third through-pin and the fourth through-pin are disconnected from the negative DC bus on the load side. The power conversion unit is completely removed from the slot.

[0145] S1006. The input capacitor discharge is completed.

[0146] As Figure 13 shown, it is a schematic flow diagram of another hot plug provided by the embodiment of the present application, specifically including the following steps:

[0147] S1301. Place the power conversion unit into the slot;

[0148] S1302. Push the power conversion unit into the specified position (the charge and discharge station of the plug-in assembly), and the DC bus on the load side charges the output capacitor through the first through-pin and the fourth through-pin;

[0149] As Figure 14 shown, when the power conversion unit is not inserted in place, the first through-pin is electrically connected to the positive DC bus on the load side, the fourth through-pin is electrically connected to the negative DC bus on the load side, and the DC bus on the load side charges the output capacitor C2 through the first resistor R1 and the second resistor R2;

[0150] S1303. The control unit determines whether the voltage of the output capacitor reaches the first threshold voltage. If so, execute S1304; otherwise, execute S1308;

[0151] S1304. The control unit starts the bidirectional active bridge DC-DC converter to enable the output capacitor to charge the input capacitor, and the staff pushes the power conversion unit to the normal working station;

[0152] The staff pushes the power unit to the normal working station, that is, the plug-in assembly is in the normal working station. The second through-pin shorts the first resistor R1, and the third through-pin shorts the second resistor R2.

[0153] S1305. The control unit determines whether the voltage of the input capacitor reaches the second threshold voltage. If so, execute S1306; otherwise, execute S1309;

[0154] S1306. The main contact of the contactor is switched from NC to NO;

[0155] As Figure 15 shown, the power conversion unit has been inserted in place. Both the first through-pin and the second through-pin are electrically connected to the positive DC bus on the load side, and both the third through-pin and the fourth through-pin are electrically connected to the negative DC bus on the load side to charge the input capacitor C1. After the input capacitor C1 is charged, that is, the voltage across the input capacitor C1 is greater than the second threshold voltage, the control unit controls the main contact of the contactor K1 to be switched from NC to NO.

[0156] S1307. The control circuit controls the switching tubes in the power circuit according to the preset control logic and algorithm, enabling the power circuit to operate normally.

[0157] S1308. If the voltage of the output capacitor does not reach the first threshold voltage after the first preset time period, a fault alarm is issued.

[0158] After receiving the fault alarm message, the staff can pull out the power conversion unit from the slot and replace it with a new one.

[0159] S1309. If the voltage of the input capacitor does not reach the second threshold voltage after the second preset time period, a fault alarm is issued.

[0160] After receiving the fault alarm message, the staff can pull out the power conversion unit from the slot and replace it with a new one.

[0161] In the power conversion unit provided by the embodiment of the present application, when the power conversion unit fails, the output capacitor gradually disconnects from the DC bus on the load side, that is, it experiences the process of direct connection, connection with the charge and discharge resistor, and complete disconnection, realizing the online "pulling out" process.

[0162] Although the output side is low-voltage DC and generally does not pose a safety risk, the discharge of the capacitor voltage also needs to be realized. On the one hand, discharge treatment is carried out on the tooling, and on the other hand, the charge and discharge resistor connected in parallel with the capacitor inside the power conversion unit is used for discharging.

[0163] After the faulty power conversion unit is detached from the power electronic transformer, in order to keep the power electronic transformer still able to operate normally and maintain the same redundancy, a power conversion unit with good performance needs to be inserted.

[0164] When inserting a power conversion unit with high performance, the output capacitor is gradually connected to the DC bus on the load side, that is, it experiences the process of complete disconnection, connection with the charge and discharge resistor, and complete connection, realizing the online "inserting" process.

[0165] During the online "inserting" process, first, "limiting" treatment is carried out, that is, the plugging component is in the charge and discharge working position, and the DC bus on the load side charges the output capacitor through the charge and discharge resistor. When the voltage of the output capacitor reaches the first threshold voltage, the power conversion unit is continuously inserted into the slot, and the plugging component is in the normal working position. The power flow of the bidirectional active bridge DC-DC converter works from right to left, charging the input capacitor C1 reversely. After waiting for the voltage of the input capacitor C1 to reach the second voltage threshold, the coil of the contactor receives the action instruction, and the main contact is adjusted to the NO (normally open) position, which is equivalent to introducing the input side of the power conversion unit into the phase voltage of the medium-voltage cascade.

[0166] Based on the same concept, an embodiment of the present application further provides a power electronic transformer. The principle of the power electronic transformer to solve technical problems is similar to that of the above-mentioned power conversion unit, and the repeated parts will not be described again.

[0167] The power electronic transformer provided by the embodiment of the present application includes a plurality of power conversion units as described in any of the above.

[0168] As Figure 16 shown, it is a schematic structural diagram of a power electronic transformer provided by an embodiment of the present application. The input side of this power electronic transformer is medium-voltage alternating current, and the output side is low-voltage direct current.

[0169] The power electronic transformer in the embodiment of the present application is divided into three groups corresponding to the A, B, and C phase inputs. Each phase is cascaded by the same number of power conversion units to jointly bear the input phase voltage. The output ends of the power conversion units are connected in parallel to form a low-voltage DC bus, that is, the load-side DC bus.

[0170] The embodiment of the present application uses the first switching switch to effectively and safely isolate the faulty power conversion unit from the high-voltage application scenario; uses the DC-DC bidirectional converter to pre-charge the input capacitor C1 of the newly added power conversion unit, which neither affects the overall operation of the system nor causes a large current impact on the power module from the front-end power grid side; uses the limit design with different lengths of the through pins to pre-charge the output capacitor C2 of the newly inserted power conversion unit; which neither affects the overall operation of the system nor causes a large current impact on the power conversion unit from the back-end load side.

[0171] The present application is described above with reference to the block diagrams and / or flowcharts showing methods, apparatuses (systems) and / or computer program products according to embodiments of the present application. It should be understood that the functions / actions specified in the blocks of the block diagrams and / or flowcharts can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, and / or other programmable data processing devices to generate a machine, so that the instructions executed by the computer processor and / or other programmable data processing devices create a method for implementing the functions / actions specified in the blocks of the block diagrams and / or flowcharts.

[0172] Accordingly, the present application can also be implemented by hardware and / or software (including firmware, resident software, microcode, etc.). Further, the present application can take the form of a computer program product on a computer-usable or computer-readable storage medium, which has computer-usable or computer-readable program code implemented in the medium for use by or in connection with an instruction execution system. In the context of the present application, the computer-usable or computer-readable medium can be any medium that can contain, store, communicate, transmit, or transport a program for use by or in connection with an instruction execution system, apparatus, or device.

[0173] Obviously, those skilled in the art can make various modifications and variations to the present utility model without departing from the spirit and scope of the present utility model. Thus, if these modifications and variations of the present utility model fall within the scope of the claims of the present utility model and their equivalent technologies, the present utility model is also intended to include these modifications and variations.

Claims

1. A power conversion unit, characterized in that, Comprising: A control circuit, a first switching switch, a power circuit, a first charge and discharge unit, and a plugging component, wherein the plugging component includes a first through-pin, a second through-pin, and a third through-pin; The control circuit is electrically connected to the control terminal of the power circuit. The first switching switch is connected between the input power supply and the input terminal of the power circuit. The first charge and discharge unit is connected between the first output terminal of the power circuit and the first through-pin. The first output terminal of the power circuit is electrically connected to the second through-pin, and the second output terminal of the power circuit is electrically connected to the third through-pin; The plugging component includes a charge and discharge working position and a normal working position. When the plugging component is in the charge and discharge working position, the first through-pin is in an electrically connected state with the first end of the output power supply, the second through-pin is in a disconnected state from the first end of the output power supply, and the third through-pin is in an electrically connected state with the second end of the output power supply; when the plugging component is in the normal working position, the first through-pin is in an electrically connected state with the first end of the output power supply, the second through-pin is in an electrically connected state with the first end of the output power supply, and the third through-pin is in an electrically connected state with the second end of the output power supply.

2. The power conversion unit according to claim 1, characterized in that The length of the first through-pin is greater than the length of the second through-pin.

3. The power conversion unit according to claim 1, characterized in that, It further includes a second charge and discharge unit, and the plugging component further includes a fourth through-pin; The second charge and discharge unit is connected between the second output terminal of the power circuit and the fourth through-pin; When the plugging component is in the charge and discharge working position, the third through-pin is in a disconnected state from the second end of the output power supply, and the fourth through-pin is in an electrically connected state with the second end of the output power supply. When the plugging component is in the normal working position, the third through-pin is in an electrically connected state with the second end of the output power supply, and the fourth through-pin is in an electrically connected state with the second end of the output power supply.

4. The power conversion unit according to claim 3, wherein The length of the fourth through-pin is greater than the length of the third through-pin.

5. The power conversion unit according to claim 1, characterized in that, The first charge and discharge unit includes at least one first resistor; If the first charge and discharge unit includes a plurality of first resistors, then the plurality of first resistors are connected in series or in parallel.

6. The power conversion unit according to claim 3, characterized in that, The second charge and discharge unit includes at least one second resistor; If the second charge and discharge unit includes a plurality of second resistors, then the plurality of second resistors are connected in series or in parallel.

7. The power conversion unit according to claim 1, characterized in that, The first switching switch includes a contactor; The first normally open contact of the contactor and the first normally closed contact of the contactor are both electrically connected to the first end of the input power supply. The second normally open contact of the contactor is electrically connected to the first input terminal of the power circuit. The second normally closed contact of the contactor is electrically connected to the second end of the input power supply and the second input terminal of the power circuit.

8. The power conversion unit according to claim 3, characterized in that, The power circuit includes an input capacitor, an output capacitor, and a DC-DC conversion unit; The first end of the input capacitor is electrically connected to the first input terminal of the DC-DC conversion unit and serves as the first input terminal of the power circuit, and the second end of the input capacitor and the second input terminal of the DC-DC conversion unit serve as the second input terminal of the power circuit; The first end of the output capacitor is electrically connected to the first output terminal of the DC-DC conversion unit and serves as the first output terminal of the power circuit, and the second end of the output capacitor is electrically connected to the second output terminal of the DC-DC conversion unit and serves as the second output terminal of the power circuit.

9. The power conversion unit according to claim 8, characterized in that, The power circuit further includes a rectification unit; The rectification unit is connected between the first switching switch and the input capacitor; The rectification unit is configured to convert the input alternating current into direct current.

10. The power conversion unit according to claim 8, characterized in that, The control circuit includes a first auxiliary power supply and a second auxiliary power supply; The input terminal of the first auxiliary power supply is electrically connected to both ends of the input capacitor, and the output terminal of the first auxiliary power supply is electrically connected to the power supply terminal of the control circuit; The input terminal of the second auxiliary power supply is electrically connected to both ends of the output capacitor, and the output terminal of the second auxiliary power supply is electrically connected to the power supply terminal of the control circuit; Both the first auxiliary power supply and the second auxiliary power supply are configured to supply power to the control circuit.

11. The power conversion unit according to claim 8, wherein The control circuit includes a third auxiliary power supply and a second switching switch; The first end of the second switching switch is electrically connected to the first end of the input capacitor, the second end of the second switching switch is electrically connected to the first end of the output capacitor, the third end of the second switching switch is electrically connected to the first input terminal of the third auxiliary power supply, and the second ends of the input capacitor and the output capacitor are electrically connected to the second input terminal of the third auxiliary power supply; The second switching switch is configured to conduct the path between the input capacitor and the third auxiliary power supply and disconnect the path between the output capacitor and the third auxiliary power supply, or disconnect the path between the input capacitor and the third auxiliary power supply and conduct the path between the output capacitor and the third auxiliary power supply.

12. The power conversion unit according to claim 11, wherein The second switching switch includes a single-pole double-throw switch; The first fixed terminal of the single-pole double-throw switch is electrically connected to the first end of the input capacitor, the second fixed terminal of the single-pole double-throw switch is electrically connected to the first end of the output capacitor, and the moving terminal of the single-pole double-throw switch is electrically connected to the first input terminal of the auxiliary power supply.

13. A power electronic transformer, characterized in that, It includes a plurality of power conversion units as described in any one of claims 1 to 12.

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