WO2023051959A1

WO2023051959A1 - Solid-state dc device

Info

Publication number: WO2023051959A1
Application number: PCT/EP2022/025457
Authority: WO
Inventors: Pavel PURGAT; Wolfgang Hauer
Original assignee: Eaton Intelligent Power Limited
Priority date: 2021-10-01
Filing date: 2022-09-30
Publication date: 2023-04-06
Also published as: GB2611345B; GB202114092D0; GB2611345A

Abstract

For a solid-state DC device (1) comprising a first conductor path (2) with a first power supply connection (3), a second conductor path (5), a first semiconductor circuit arrangement (11) with a first power semiconductor (12) in the first conductor path (2), a first switchable electrical arrangement (8) for building an electrical connection from the first conductor path (2) to the second conductor path (5), a second switchable electrical arrangement (9) arranged between the first semiconductor circuit arrangement (11) and the first load connection (4), the second switchable electrical arrangement (9) comprises two parallel switching paths (14, 15, 17, 18), it is suggested, that the first semiconductor circuit arrangement (11), the first switchable electrical arrangement (8) and the second switchable electrical arrangement (9) are individually on and/or off to limit the electric current at the first power supply connection (3) to a predefined current level.

Description

Solid-state DC device

The present disclosure relates to a Solid-state DC device according to the generic part of claim 1.

It is well known, that DC grids or parts of DC devices connected to a grid comprise capacitances respective capacitors for stabilising the DC grid and/or as fast energy and/or power storing part. For industrial DC grids these capacitors have a very high capacitance, for example from 1 farad up to 10.000 farad, if the capacitors are supercapacitors. By activating of such a DC grid, it is necessary to charge the capacitors prior to any operation of the DC grid. Capacitors act, load and reload, much faster than most other electric parts, especially much faster than accumulators. Especially at the beginning of loading capacitors of a grid, the current would be much higher than currents in this grid in normal operation. This current would be high enough to trip a circuit breaker like a short-circuit, and stops the further loading.

As the high loading currents and their possibility to trip a circuit breaker are known, different devices and ways to operate these devices are known to limit the current during starting the operation of such DC grids. These well-known devices and/or operation are typically complicated and would need electrotechnical engineers to operate them.

It is an object of the present invention to overcome the drawbacks of the state of the art by providing a solid-state DC device with which it is possible to charge capacitors respectively capacitances of a system without tripping a circuit breaker of the connected power supply grid, which is safe and could be operated easy, is achieved.

According to the invention, the aforementioned object is solved by the features of claim 1.

The solid-state DC device limits the current during charging of at least one capacitor respectively capacitance, especially during charging of the at least one capacitor. The solid-state DC device provides a current which would be high enough to charge the capacitor and low enough that a circuit breaker between the solid-state DC device and the power supply grid would not react and switch off the connection to the power supply.

The solid-state DC device can operate without a required human for operating it.

The solid-state DC device saves the necessary current for the capacitors and the connection to the power supply and would limit the necessary time for starting, respectively operating the DC-grid after it was locked off.

The dependent claims describe further preferred embodiments of the invention.

The invention is described with reference to the drawings. The drawings show only exemplary embodiments of the invention.

Fig. 1 illustrates a preferred embodiment of a solid-state DC device embodied in a bidirectional DC-circuit breaker during current limiting; and

Fig. 2 the solid-state DC device according Fig. 1 in standby with all switches open.

Fig. 1 and 2 illustrate a solid-state DC device 1 comprising: a first conductor path 2 from a first power supply connection 3 of the solid-state DC device 1 to a first load connection 4 of the solid-state DC device 1, a second conductor path 5 from a second power supply connection 6 of the solid-state DC device 1 to a second load connection 7 of the solid-state DC device 1, a first semiconductor circuit arrangement 11 of the solid-state DC device 1 arranged in the first conductor path 2, the first semiconductor circuit arrangement 11 comprising at least a first power semiconductor 12, a first switchable electrical arrangement 8 for building an electrical connection from the first conductor path 2 after the first power semiconductor 12 to the second conductor path 5, a second switchable electrical arrangement 9 arranged between the first semiconductor circuit arrangement 11 and the first load connection 4, the second switchable electrical arrangement 9 comprises a first parallel path 14 with a first switch 15 and a first electric energy-storing-part 16 and a second parallel path 17 with a second switch 18, a control and driver unit 13 configured to drive the first semiconductor circuit arrangement 11 , the first switchable electrical arrangement 8 and the second switchable electrical arrangement 9 with control signals, with the solid-state DC device 1 is embodied to limit an electric current at the first power supply connection 3 to a predefined current level, and with the control and driver unit 13 being embodied to activate the first semiconductor circuit arrangement 11 , the first switchable electrical arrangement 8 and the second switchable electrical arrangement 9 individually on and/or off to limit the electric current at the first power supply connection 3.

The solid-state DC device 1 limits the current during charging of at least one capacitor 35 respectively capacitance, especially during charge of the at least one capacitor 35. The solid-state DC device 1 provides a current which would be high enough to charge the capacitor 35 and low enough that a circuit breaker between the solid-state DC device 1 and the power supply grid would not react and switch off the connection to the power supply.

The solid-state DC device 1 saves the necessary current for the capacitors 35 and the connection to the power supply and would limit the necessary time for starting, respectively operating the DC-grid was locked off.

The solid-state DC device 1 is a device to operate in an electric grid only with solid- state parts. A solid-state DC device 1 may have and use mechanical switching parts, but only in bypass parts. No mechanical switch is used as disconnecting part for high current conductor part 2, 5.

The present solid-state DC device 1 is preferably a low-voltage solid-state DC device 1 . Low voltage DC usually means up to 1 ,500 volts DC voltage. The solid-state DC device 1 could be integrated in another electric device or it could be a separated device with an own casing. The solid-state DC device 1 could be embodied as device which could only be operated in a single direction, with one definite side to be connected to a power supply and another definite side to be connected to at least one load. Preferably the solid-state DC device 1 is a bidirectional solid-state DC device 1. Fig. 1 and 2 are showing a bidirectional solid- state DC device 1. The bidirectional solid-state DC device 1 comprises more parts than the single direction solid-state DC device 1 , to be operated in both directions.

The solid-state DC device 1 could be embodied as device which has only the functionality of limiting the electric current at the power supply connection. Preferably the solid-state DC device 1 is part of a DC-circuit breaker or a DC-circuit breaker comprising a solid-state DC device 1 or a DC-circuit breaker and the embodied solid-state DC device 1 using the same parts for switching off the grid and for limiting the electric current.

The solid-state DC device 1 comprises a first conductor path 2 for a first electric potential, especially plus, and a second conductor path 5 for a second electric potential, especially minus. One end of the first conductor path 2 is a first power supply connection 3 of the solid-state DC device 1 , the outer end is a first load connection 4 of the solid-state DC device 1. The second conductor path 5 reaches from a second power supply connection 6 of the solid-state DC device 1 to a second load connection 7 of the solid-state DC device 1 .

The solid-state DC device 1 comprises a first semiconductor circuit arrangement 11 which is arranged in the first conductor path 2. The first semiconductor circuit arrangement 11 comprises at least a first power semiconductor 12, especially an IGBT. Preferably the first semiconductor circuit arrangement 11 comprises a second power semiconductor 23 serial to the first power semiconductor 12. The solid-state DC device 1 would have these two power semiconductors 12, 23 if it is a bidirectional solid-state DC device 1 . In this case the first and the second power semiconductors 12, 23 would be arranged bidirectional to each outer. Preferably at least one voltage-dependent resistor or varistor 30 is connected parallel to the first semiconductor circuit arrangement 11 .

The solid-state DC device 1 comprises a first switchable electrical arrangement 8 for building an electrical connection from the first conductor path 2 to the second conductor path 5. The connection of the first switchable electrical arrangement 8 with the first conductor path 2 is located after the first power semiconductor 12, preferably essentially immediately after the first power semiconductor 12.

The first switchable electrical arrangement 8 can have different parts and also other functionalities in the solid-state DC device 1 than building a connection between the first conductor path 2 and the second conductor path 5.

Preferably, the first switchable electrical arrangement 8 is a first snubber 20, respectively a snubber circuit arrangement, which is connected parallel to the first power semiconductor 12. The first snubber 20 would principally be important for the safety of the first semiconductor circuit arrangement 11 by using the solid-state DC device 1 as circuit breaker 29, and in the actual solid-state DC device 1 it would be used for limiting the current. The first snubber 20 comprises at least one switch 21 . The first snubber 20 further comprises at least one resistor 36, one capacitor 37 and one diode 38, as it is shown in Fig. 1 and 2.

In the preferred bidirectional embodiment of the solid-state DC device 1 the first switchable electrical arrangement 8 would comprise a first snubber 20 parallel to the first power semiconductor 12 and a second snubber 32 parallel to the second power semiconductor 23. The second snubber 32 comprises another switch 31 , at least one resistor 36, one capacitor 37 and one diode 38, as it is shown in Fig. 1 and 2. The second snubber 32 respectively the parts of the second snubber 32 are arranged contrary to the first snubber 20 respectively the parts of the first snubber 20.

The solid-state DC device 1 comprises a second switchable electrical arrangement 9. The second switchable electrical arrangement 9 is embodied as parallel arrangement comprising a first parallel path 14 and a second parallel path 17. The first parallel path 14 comprises a first switch 15 and a first electric energy-storing-part 16, which is connected serially to the first switch 15. The second parallel path 17 comprises a second switch 18. The second switchable electrical arrangement 9 is arranged between the first semiconductor circuit arrangement 11 and the first load connection 4. If the first switch 15 or the second switch 18 is in an ON position respective closed, the parallel paths 14, 17 witch the switch 15, 18 in ON position is part of the first conductor path 2.

In the preferred bidirectional embodiment, the solid-state DC device 1 comprises a third switchable electrical arrangement 10 which is arranged between the first semiconductor circuit arrangement 11 and the first power supply connection 3. The third switchable electrical arrangement 10 has the same parts as the second switchable electrical arrangement 9 and is arranged opposite to the second switchable electrical arrangement 9. The third switchable electrical arrangement 10 comprises a third parallel path 24 with a third switch 25 and a third electric energy- storing-part 26 and a fourth parallel path 27 with a fourth switch 28.

Preferably the solid-state DC device 1 further comprises a second electric energy- storing-part 33 which is arranged in the first conductor path 2 between the second switchable electrical arrangement 9 and the first load connection 4. Preferably the solid-state DC device 1 also comprises a fourth electric energy-storing-part 34 which is arranged in the first conductor path 2 between the first power supply connection 3 and the third switchable electrical arrangement 10.

Preferably the first electric energy-storing-part 16 and/or the second electric energy- storing-part 33 and/or the third electric energy-storing-part 26 and/or the fourth electric energy-storing-part 34 is/are embodied as inductor 22. Inductors also save electrical energy and they are also very fast in their reaction time.

The solid-state DC device 1 comprises a control and driver unit 13 configured to drive at least the first semiconductor circuit arrangement 11 , the first switchable electrical arrangement 8, the second switchable electrical arrangement 9 with control signals and various further parts of the solid-state DC device 1 . The control and driver unit 13 is connected to each of these parts to communicate with them. These connections are not shown in Fig. 1 and 2. Preferably the control and driver unit 13 comprises a pC.

For limiting the current at first power supply connection 3 to a value small enough to avoid a tripping of a circuit breaker it would be necessary that the control and driver unit 13 knows or suggests a value of the actual current. Preferably the value of this current will be measured. This could be measured outside the solid-state DC device 1, especially it could be measured in the circuit breaker, which would be connected to the control and driver unit 13 of the solid-state DC device 1.

Preferably the solid-state DC device 1 comprises a first current measuring arrangement 19 for measuring the electric current at the first power supply connection 3. This first current measuring arrangement 19 would be connected to the control and driver unit 13 to send the measured current value to the control and driver unit 13.

The solid-state DC device 1 is embodied to limit an electric current at respective nearly to the first power supply connection 3 to a predefined current level. It is provided that the control and driver unit 13 is embodied or programmed to activate the first semiconductor circuit arrangement 11 , the first switchable electrical arrangement 8 and the second switchable electrical arrangement 9 individually on and/or off for limiting the electric current at the first power supply connection 3. Fig. 1 shows the different current parts during this operation.

If the first semiconductor circuit arrangement 11 comprise a second power semiconductor 23, the second power semiconductor 23 is switched on during the limiting of the electric current at the first power supply connection 3. In this case the second power semiconductor 23 is a conductive part for this operation.

Preferably, the control and driver unit 13 is embodied or programmed to individually switch, respectively activate the parts in the following way during limiting of the electric current at the first power supply connection 3. The first switchable electrical arrangement 8 is activated to build a predefined electrical connection, comprising a resistor 36 and a diode 38, between the second conductor path 5 and the first conductor path 2. At the second switchable electrical arrangement 9 the first switch 15 in the first parallel path 14 is closed, respectively in on position, and the second switch 18 in the second parallel path 17 is opened, respectively in off position. This builds a damping electric loop with a resistance higher than the resistance of the first conductor path 2 and with saved electric energy.

Further, if the electric current at the first power supply connection 3 is lower than the predefined current level - the control and driver unit 13 switches the first power semiconductor 12 to on state. This enables current to flow from the power grid to the load capacitor 35 limited only by the power grid and the resistances of the first conductor path 2.

If the electric current at the first power supply connection 3 is higher or becomes higher than the current level, the control and driver unit 13 switches the first power semiconductor 12 off. The current part from the power grid is interrupted. In this case the current is flowing using the first switchable electrical arrangement 8. The current getting lower, and after a predefined time or if the measured current at the first power supply connection 3 is lower than a second predefined current level, the control and driver unit 13 switches the first power semiconductor 12 on again. Said switching of the first power semiconductor 12 between on and off will be continued until the load capacitor 35 is charged.

The current levels for switching the first power semiconductor 12 on or off can be different, to make the operation slower and more safe. Further the control and driver unit 13 my preferably be connected to an outside part to insert details like the at least one current level.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the appended claims. The exemplary embodiments should be considered as descriptive only and not for purposes of limitation. Therefore, the scope of the present invention is not defined by the detailed description but by the appended claims.

Hereinafter are principles for understanding and interpreting the actual disclosure.

Features are usually introduced with an indefinite article "one, a, an ". Unless otherwise stated in the context, therefore, "one, a, an" is not to be understood as a numeral.

The conjunction "or" has to be interpreted as inclusive and not as exclusive, unless the context dictates otherwise. "A or B" also includes "A and B", where "A" and "B" represent random features.

By means of an ordering number word, for example "first ", "second" or "third ", in particular a feature X or an object Y is distinguished in several embodiments, unless otherwise defined by the disclosure of the invention. In particular, a feature X or object Y with an ordering number word in a claim does not mean that an embodiment of the invention covered by this claim must have a further feature X or another object Y.

An "essentially" in conjunction with a numerical value includes a tolerance of ± 10% around the given numerical value, unless the context dictates otherwise.

For ranges of values, the endpoints are included, unless the context dictates otherwise.

Claims

1 . Solid-state DC device (1 ) comprising: a first conductor path (2) from a first power supply connection (3) of the solid-state DC device (1 ) to a first load connection (4) of the solid-state DC device (1 ), a second conductor path (5) from a second power supply connection (6) of the solid- state DC device (1 ) to a second load connection (7) of the solid-state DC device (1 ), a first semiconductor circuit arrangement (11 ) of the solid-state DC device (1 ) arranged in the first conductor path (2), the first semiconductor circuit arrangement (11 ) comprising at least a first power semiconductor (12), a first switchable electrical arrangement (8) for building an electrical connection from the first conductor path (2) after the first power semiconductor (12) to the second conductor path (5), a second switchable electrical arrangement (9) arranged between the first semiconductor circuit arrangement (11 ) and the first load connection (4), the second switchable electrical arrangement (9) comprises a first parallel path (14) with a first switch (15) and a first electric energy-storing-part (16) and a second parallel path (17) with a second switch (18), a control and driver unit (13) configured to drive the first semiconductor circuit arrangement (11 ), the first switchable electrical arrangement (8) and the second switchable electrical arrangement (9) with control signals, characterised in, that the solid-state DC device (1 ) is embodied to limit an electric current at the first power supply connection (3) to a predefined current level, and that the control and driver unit (13) is embodied to activate the first semiconductor circuit arrangement (11 ), the first switchable electrical arrangement (8) and the second switchable electrical arrangement (9) individually on and/or off to limit the electric current at the first power supply connection (3).

2. Solid-state DC device (1 ) according to claim 1 , characterised in, that the control and driver unit (13) is embodied to

- activate the first switchable electrical arrangement (8) to build a predefined electrical connection between the first conductor path (2) and the second conductor path (5),

- close the first switch (15) of the first parallel path (14) and

- open the second switch (18) of the second parallel path (17) during limiting of the electric current at the first power supply connection (3).

3. Solid-state DC device (1 ) according to claim 1 or 2, characterised in, that the control and driver unit (13) is embodied to switch on the first power semiconductor (12), if the electric current at the first power supply connection (3) is lower than the current level.

4. Solid-state DC device (1 ) according to one of the claims 1 to 3, characterised in, that the control and driver unit (13) is embodied to switch off the first power semiconductor (12), if the electric current at the first power supply connection (3) becomes higher than the current level.

5. Solid-state DC device (1 ) according to one of the claims 1 to 4, characterised in, that the solid-state DC device (1 ) comprises a first current measuring arrangement (19) for measuring the electric current at the first power supply connection (3), and that the first current measuring arrangement (19) is connected to the control and driver unit (13).

6. Solid-state DC device (1 ) according to one of the claims 1 to 5, characterised in, that the first switchable electrical arrangement (8) is a snubber (20) comprising at least one switch (21 ), and that the first switchable electrical arrangement (8) is connected parallel to the first semiconductor circuit arrangement (11 ).

7. Solid-state DC device (1 ) according to one of the claims 1 to 6, characterised in, that the first electric energy-storing-part (16) is embodied as inductor (22).

8. Solid-state DC device (1 ) according to one of the claims 1 to 7, characterised in, that the solid-state DC device (1 ) is a bidirectional solid-state DC device (1 ).

9. Solid-state DC device (1 ) according to one of the claims 1 to 8, characterised in, that the first semiconductor circuit arrangement (11 ) comprises a second power semiconductor (23) serial to the first power semiconductor (12), and that the second power semiconductor (23) is switched on during the limiting of the electric current at the first power supply connection (3).

10. Solid-state DC device (1 ) according to claim 1 , characterised in, that the solid-state DC device (1 ) comprises a third switchable electrical arrangement (10) arranged between the first semiconductor circuit arrangement (11 ) and the first power supply connection (3), the third switchable electrical arrangement (10) comprises a third parallel path (24) with a third switch (25) and a third electric energy-storing-part (26) and a fourth parallel path (27) with a fourth switch (28).

11. DC-circuit breaker (29) comprising a, especially bidirectional, solid-state DC device (1 ) according to one of the claims 1 to 10.