Test field with modular DC voltage bus

Abstract

The invention relates to a test field having a modular DC voltage bus for electrically testing a test piece at a DC voltage by means of a strong electrical power, comprising at least one energy source, a test station for the test piece and the modular DC voltage bus, the invention relates to a test station for an energy source having a generator for an alternating voltage and a converter with a first bipolar direct voltage connection, having a resonant converter with a second bipolar direct voltage connection, and having a step-down chopper with a bipolar direct voltage connection for a test piece, the invention relates to a DC voltage bus having a series circuit of DC distributors, the DC distributors having busbars which can be connected in series and branches which lead from the busbars to a third bipolar DC voltage interface and are equipped with disconnecting switches, wherein each first direct-current voltage interface and each second direct-current voltage interface are connected with one third direct-current voltage interface.

Description

Technical Field

[0001] This invention relates to a test field. The test field described herein is used to electrically test test objects, such as electric drives or driving batteries of electric vehicles, at relatively high power levels in the tens of kW range, under DC voltage conditions between two poles. At multiple test stations within the test field, one of the test objects is connected or can be connected to. Here, the test object can absorb electrical power from the test stations and / or output electrical power to the test stations. Background Technology

[0002] As known from WO 2021 / 174278 A1, test benches for electric operation typically include converter assemblies with multiple converters, which are now used to test electric vehicles, hybrid vehicles, drive systems of conventional vehicles with internal combustion engines, mechanical components such as transmissions, or the battery storage itself. Battery storage is typically tested in parallel, where multiple battery cells, battery modules, or battery packs are simultaneously tested using converters arranged in parallel. Summary of the Invention

[0003] The objective of this invention is to propose improvements related to testing environments.

[0004] This task is accomplished using the test field according to claim 1. Preferred or advantageous embodiments of the invention, and other types of invention, are derived from the additional claims, the following description, and the accompanying drawings.

[0005] A test field is a test field for bipolar test pieces, and is therefore used to test or connect bipolar test pieces. The two poles form a positive and a negative terminal for a DC voltage. The test field is used for electrical testing of the test piece. The test piece is tested with the DC voltage between the two poles by means of current that can be fed into and / or drawn from each of the respective test pieces. Here, the test field is specified to withstand relatively strong electrical power testing. Here, the test field is designed for relatively strong electrical loads on the test pieces. The possible rated / maximum electrical power of each test piece is typically 250 kW to 1 MW, while the rated voltage is typically approximately 200 V to approximately 800 V, and the rated current is typically 1000 A to 2000 A.

[0006] The test field contains at least one energy source. The energy source can feed electrical power into the rest of the test field and, if necessary, absorb electrical power from the rest of the test field. The terms "source / generator / etc." should be understood broadly here: the "energy source" is designed bidirectionally, for example, if necessary, and can also function as an energy absorber (Energiesenke) when required.

[0007] Each energy source includes a generator (bidirectional if necessary). The generator is used to produce AC voltage for the rest of the test field. Additionally, each energy source includes at least one converter connected to the generator. The converter is used to convert the AC voltage present on the generator between AC and DC voltage. Therefore, on the side opposite to the generator (from a circuit technical perspective), each converter or energy source includes at least one bipolar first DC voltage interface.

[0008] The test range also includes multiple test stations. Each test station is used to test or connect one test piece. The test stations are also implemented bipolarly to bipolarly connect the test pieces and thus supply them with DC voltage. Each test station contains a resonant converter. The resonant converter or test station has a bipolar second DC voltage interface. Each test station contains a buck chopper connected to its respective resonant converter. On the side opposite to the resonant converter (see above for circuitry details), the test station or buck chopper has a bipolar DC voltage connection. This bipolar DC voltage connection is used for bipolar connection of the respective test piece.

[0009] The resonant converter and buck chopper are used to convert the DC voltage at the second DC voltage interface of the bipolar circuit to a lower DC voltage at the DC voltage connection point via an intermediate AC voltage (bidirectional if necessary).

[0010] The test field includes a modular DC voltage bus.

[0011] A DC voltage bus comprises a series circuit of at least two DC distributors. Each DC distributor contains a bipolar bus. The DC distributors can be connected in series with respect to their buses. That is, by connecting the bipolar (sub)buses of each DC distributor in series, a common, continuous bipolar (total) bus is formed, passing through all the series-connected DC distributors.

[0012] Each DC distributor contains at least two branches. Each branch is bipolar and bipolarly connected to a bus. Therefore, each branch is directed from the bus to its own bipolar third DC voltage interface. In other words, each branch is connected to its own or the DC distributor's third DC voltage interface.

[0013] Each branch contains a bipolar isolating switch. Thus, through the isolating switch, each third DC voltage interface can be electrically bipolar and therefore completely isolated from the bus, or can be electrically connected to / from the bus.

[0014] In the test field, each of the first DC voltage interfaces and each of the second DC voltage interfaces is connected to one of the third DC voltage interfaces. Therefore, all power sources and test stations are electrically and bipolarly connected to each other via a DC voltage bus.

[0015] Preferably, at least one of the DC splitters has exactly six branches. In particular, on one of the DC splitters, the power source is connected to a total of four of its branches. The test station is connected to or can be connected to the remaining two branches.

[0016] However, in principle, any number of DC distributors can be set up, and the appropriate number can be set up for each specific application.

[0017] The modularity of the DC voltage bus allows test sites to be easily scaled up or down within the design scope by attaching / removing additional DC distributors in series circuits. Due to the disconnecting switches, certain branches can be selectively disconnected without having to disconnect others. For example, the disconnecting switch can be disconnected in one branch, allowing the connected test station to be removed or replaced there, or maintenance work to be performed at that test station since it is de-energized. Other test stations or the remaining test sites can continue to operate.

[0018] In a preferred embodiment, at least one of the disconnecting switches has a safety device to prevent re-energization. Therefore, after the disconnecting switch is opened, it can be ensured, in a common manner, that the disconnecting switch is protectively prevented from being re-energized. Thus, operation at the energy source or test station connected to the relevant third DC voltage interface can be carried out without danger. For example, the safety device is a fastening device for a padlock used to prevent re-energization of the disconnecting switch in its presence / placement.

[0019] In a preferred embodiment, at least one branch includes at least one, particularly two, bridging connections. In other words, at least one branch has at least one bridging connection. Each bridging connection functions for one of the two poles. The bridging connection disconnects the electrical connection of the associated pole line, i.e., one pole of the bus, from the pole of the third DC voltage interface. Shorting elements (test field elements) may be selectively installed in the bridging connection to bridge it. The electrical connection of the poles through the bridging connection is thus re-established. Alternatively, protective elements (test field elements) may be installed in the bridging connection to bridge it. Electrical protective elements, such as electric fuses, protect the corresponding pole, and thus protect the third DC voltage interface or the entire branch, for example, against overcurrent.

[0020] Therefore, the shorting element or protective element bridges their respective bridging connections, and re-establishes an electrical connection between the third interface and the bus with respect to that pole (if necessary, via protective ground or through a short circuit). Thus, branches can be widely used, especially for connecting energy sources (with shorting elements installed) or test stations (with protective elements installed). In other words, branches are therefore configurable.

[0021] In a preferred embodiment, the test range specifically includes exactly one pre-charging device. The pre-charging device can be selectively or as needed connected to exactly one of the test stations. The pre-charging device is configured to feed pre-charge into the test station currently connected to it. This occurs particularly before the test station is attached to the rest of the test range. Attachment is achieved by establishing an electrical connection with the bus, i.e., closing the disconnect switch. Thus, the pre-charging device can be connected and activated, for example, when the relevant test station has already been connected to the third interface using its second interface, but the disconnect switch remains open. Therefore, by pre-charging the capacitors that may be present in the test station, the disconnect switch can be closed protectively or the connection between the test station and the bus can be established without, for example, due to the surge current flowing through the branches of the capacitors to be charged or discharged in the test station.

[0022] In a preferred embodiment, at least one of the energy sources has multiple, particularly four, bipolar first DC voltage interfaces. In other words, the energy source or its converter is connected to a DC bus / bus via multiple parallel bipolar interfaces, thereby reducing the current load of each interface. For example, an energy source with a rated power of 1 MW can be divided into four bipolar modules / connections (each 250 kW).

[0023] In a preferred embodiment, all DC distributors are implemented identically. This results in a particularly common concept for scalable test fields.

[0024] In a preferred embodiment, the test range includes at least two energy sources. Therefore, each energy source can be implemented at a lower rated power, but can still provide a higher total rated power to the test range.

[0025] In a preferred variant of this embodiment, at least two energy sources are connected to two different DC distributors. Therefore, the feed or electrical load on the DC distributors is reduced by utilizing the energy sources or their connections.

[0026] In a preferred embodiment, at least one of the DC distributors is not connected to a power source. Therefore, this DC distributor provides a particularly large number of third DC voltage interfaces for connecting to a test station.

[0027] This invention is based on the following findings, observations, or ideas, and also includes the following preferred embodiments. These embodiments are hereby referred to, in part, simply, as "the present invention." The embodiments may also include or correspond to portions or combinations of the embodiments described above, and / or, if necessary, include embodiments not mentioned to date.

[0028] Therefore, according to the present invention, a DC distributor (DC: direct current) is obtained, especially a DC distributor with a selectively distributed and pre-charged intermediate circuit.

[0029] This invention is based on the following observations in practice:

[0030] Devices in the DC intermediate circuit (bus) are directly connected. Therefore, the entire intermediate circuit (bus) must be shut down for maintenance purposes. According to the present invention, the intermediate circuit (bus) need not be shut down. This is based on the selective disconnection (isolating switch) and pre-charging (pre-charging device) of each DC branch.

[0031] This invention relates to the following topologies: the devices under consideration are highly dynamic, feedback-enabled DC voltage sources and DC receiving devices (test stations) used for testing electrical components (test pieces) and for simulating batteries and other electrical storage devices in test benches (test modules). Typical test pieces here are drive and storage components, such as batteries, electric drives, converters, fuel cells, solar cells, or supercapacitors.

[0032] In the topology under consideration, high DC power (typically 250 kW to 1 MW) is provided from the branches (buses / DC voltage connections) under high voltage (up to 1500 V) and high current (up to 2000 A).

[0033] Because of the DC intermediate circuit bus (DC voltage bus), a common DC intermediate circuit can be implemented on multiple test benches (test stations).

[0034] This invention is based on the following findings:

[0035] Especially in large test ranges, the central DC intermediate circuit (DC voltage bus) provides various advantages throughout the test range.

[0036] Therefore, the alternating power flow (charging / discharging, acceleration / recovery) typically generated by the test device during testing can be compensated in the intermediate circuit, thereby significantly reducing the grid connection (first DC voltage interface) in the test field compared to conventional methods.

[0037] However, a drawback of this system is that in order to maintain and repair a particular test station (also known as a "DCU": DC unit, a power unit consisting of RK and TSB, RK: resonant converter: a power module for potential isolation (transformer principle) / TSB: buck chopper bridge: a power module for regulating output voltage), the entire test field must be shut down, or all DCUs (test stations) supplied by the UWR ("converter": general-purpose inverter / grid converter: generating DC intermediate circuit) must be disconnected in order to ensure personnel safety during operation.

[0038] Therefore, the basic concept of this invention is as follows:

[0039] Instead of direct coupling between the DCU (Test Unit) and UWR (Urban Resistor), DC power is directed through a modular DC distributor (modular DC voltage bus). The DC distributor allows for selective disconnection of individual DC paths (branches) (isolating switches) and prevents reconnection (with a safety device to prevent reconnection).

[0040] Due to the presence of large intermediate circuit capacitors, high turn-on current typically occurs when reconnecting to the DC mains (attaching the test module to the bus). This problem is mitigated using a special pre-charge device. A modular approach is also employed, allowing one pre-charge device to be used for multiple DC paths (branch / test modules) since it is not necessary to simultaneously connect multiple DCUs (test modules).

[0041] The connection section (branch) may be equipped with a DC fuse (a protective element in the bridging connection section) to connect to the DCU (test station), or with a bridge (a short-circuiting element in the bridging connection section) to connect to the energy source.

[0042] The DC fuse in the current path is isolated from the adjacent current path, so that the fuse (protective element) can be replaced at a single disconnected current path (the bridging connection in the branch with the disconnected disconnector). Attached Figure Description

[0043] Further features, effects, and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention, along with the accompanying drawings. These are illustrated herein with schematic diagrams:

[0044] Figure 1 A schematic block diagram illustrates a test field with two test stations and one energy source.

[0045] Figure 2 It shows Figure 1 The test field was expanded, and an energy source and eight test stations were added, along with a more detailed DC voltage bus with a DC distributor.

[0046] Figure 3 It shows Figure 2 A detailed diagram of a segment of the test field, which features a central DC distributor within a DC distributor. Detailed Implementation

[0047] Figure 1 A test field 2 is shown for the bipolar test element 4. In the example, two test elements 4 are actually connected to the test field 2. Electrical testing of the test elements 4 is performed using the test field 2. For this purpose, based on the testing, a high power 6 of up to 1 MW of electricity is fed into or derived from the test element 4. In the example, the high power 6 is marked by a double arrow.

[0048] In the example, each test piece 4 is shown, which consists of a test device 8 in the form of a DC box (hereinafter referred to as a DC box) and an actual test piece in the form of a DUT 10 (Device Under Test). These two DUTs 10 are currently the driving battery and drive motor of an electric vehicle. The DC box is used to connect the DUT 10 to the test field 2.

[0049] Test site 2 includes an energy source 12, which in turn includes a generator 14 and an inverter 16. The generator 14 provides an AC voltage UW (in this example, a three-phase AC voltage of 400 V). The inverter 16 is connected to the generator 14 and converts the AC voltage UW into a DC voltage UG, which is applied to the first DC voltage interface 18 of the bipolar junction of the inverter 16 or the energy source 12.

[0050] Test site 2 also includes two bipolar test stations 20. Each test station 20 is used to connect exactly one test piece from test piece 4.

[0051] Each test station 20 includes a resonant converter 22 and a buck chopper 24. The resonant converter 22 or test station 20 has a bipolar second DC voltage interface 26. The buck chopper 24 or test station 20 has a bipolar DC voltage connection 28 for its respective test piece 4 on the side opposite to the resonant converter 22. The resonant converter 22 converts the DC voltage UG at the second DC voltage interface 26 to an AC voltage UW and then back to DC voltage, which is then converted by the buck chopper 24 to a variable amplitude DC voltage UG at the DC voltage connection 28.

[0052] Test site 2 also includes a modular DC voltage bus 30 with a bipolar bus 32. A first DC voltage interface 18 and a second DC voltage interface 26 are connected to the DC voltage bus 30, as described below. Thus, the DC voltage bus 30 or bus 32 distributes the DC voltage UG between the power source 12 and the test station 20.

[0053] Therefore, the DC voltage bus 30 implements the DC voltage intermediate circuit in the test field 2, and here it guides the 825V DC voltage UG during operation.

[0054] Figure 2 It shows Figure 1 Test Field 2 is part of Alternate Test Field 2. Alternate Test Field 2 is relative to... Figure 1 The test range has been expanded, and in addition to Figure 1 In addition to the test site, there is also a second energy source 12, identical to the first energy source 12, and... Figure 1 The test station 20 is the same as the eight other test stations 20. All power sources 12 and test stations 20 are connected to the DC voltage bus 30 or busbar 32 via their respective first DC voltage interface 18 and second DC voltage interface 26.

[0055] However, Figure 2 Now shown in detail, the DC voltage bus 30 is modularly constructed from a total of three DC distributors 34. The DC distributors 34 are connected in series. Each DC distributor 34 contains a bipolar bus 32, wherein the buses 32 are electrically connected in series to form a unique bipolar bus 32 that runs continuously through all three DC distributors 34, as explained further below.

[0056] Therefore, test site 2 contains two power sources 12. The two power sources 12 are connected to different DC distributors 34. One of the DC distributors 34 is not connected to any power source 12.

[0057] Figure 3 A fragment diagram of test field 2 or DC voltage bus 30 is shown, and therefore in Figure 2 The DC distributor 34 is shown in detail in the example of the intermediate DC distributor 34. In test field 2, all DC distributors 34 are implemented identically, thus corresponding to, as in Figure 3 The DC distributor described in detail (possibly excluding the equipment of the bridging connection part 44).

[0058] Figure 3 This shows how the bipolar busbars 32 of each DC distributor 34 are connected in series to form a unique, continuous busbar 32 through all three DC distributors 34.

[0059] Figure 3The connections of the energy source 12 and test station 20 to the DC voltage bus 30 or DC distributor 34 are also shown in detail. For this purpose, in the example, the DC distributor 34 has six bipolar branches 36, each connected to the bus 32 on one side and terminating at its respective third DC voltage interface 38 on the other. Each branch 36 includes its own bipolar disconnect switch 40. The bipolar disconnect switch is used to bipolarly connect the respective third DC voltage interface 38 to the bus 32 or disconnect the respective third DC voltage interface 38 from the bus (for overview purposes, the disconnect switch 40 is shown in the figures only for three of the branches 36).

[0060] The electrical connection between the energy source 12 and the test station 20 and the DC voltage bus 30 is implemented in detail, such that one of the first DC voltage interface 18 or the second DC voltage interface 26 is bipolarly connected to one of the third DC voltage interfaces 38.

[0061] Figure 3 It is shown in detail that, in energy source 12, for a generator 14 with a rated power of 1 MW, four converters 16, each with a rated power of 250 kW, are provided so that the converters can be implemented modularly and thus in an improved manner. Therefore, Figure 3 The energy source 12 also has multiple (four in this case) first DC voltage interfaces 18.

[0062] Each disconnector switch 40 has a safety device 42, not shown in detail here, to prevent reconnection. Therefore, in the event that one of the disconnectors is disconnected, i.e., the electrical connection between bus 32 and the third DC voltage interface 38 is interrupted, reconnection of the disconnector switch or re-establishment of the electrical connection is prevented, thus avoiding accidents in a common manner.

[0063] For two of the branches 36, in Figure 3 As exemplarily shown, these branches each include a bridging connection 44 at both poles. The bridging connections here unipolarly separate the connection between the bus 32 and the third DC voltage interface 38, thus ensuring that there is initially no electrical connection between the two components. However, a shorting element 46 or a protection element 48 may be selectively installed in the bridging connection 44.

[0064] Currently, for each of the four left branches 36 in the attached figure, two shorting elements 46 are installed to re-close the respective electrical connection between the bus 32 and the third DC voltage interface 38 via the bridging connection 44. Two protection elements 48 are installed in each of the two right branches 36. Thus, the branches 36 are configured to connect the energy source 12 to the bus 32 via the shorting elements 46, but also to electrically protect the test station 20 in a conventional manner via the protection elements 48. The protection elements 48 (here, DC fuses) are isolated relative to adjacent current paths / polarities in a manner not shown.

[0065] Here, test station 2 includes a pre-charging device 50. The pre-charging device can be selectively connected to exactly one of the test stations 20 at specific time intervals and is configured for subsequent operation: when test station 20 is connected to the third DC voltage interface 38 via its second DC voltage interface 26 with the disconnecting switch 40 open, pre-charging 52 is fed into test station 20 before it is attached to bus 32, i.e., before closing the disconnecting switch 40. For example, internal capacitors within test station 20 are charged. This prevents undesirably high closing current flow between bus 32 and test station 20 when the disconnecting switch 40 is subsequently closed.

[0066] List of reference numerals

[0067] 2 Test Field

[0068] 4 Test pieces

[0069] 6 High power

[0070] 8. Testing Equipment

[0071] 10 DUT

[0072] 12 Energy Sources

[0073] 14 Generator

[0074] 16 Converters

[0075] 18 First DC Voltage Interface

[0076] 20 test stations

[0077] 22 Resonant Converter

[0078] 24. Buck Chopper

[0079] 26 Second DC voltage interface

[0080] 28 DC voltage connection part

[0081] 30 DC voltage bus

[0082] 32 busbars

[0083] 34 DC distributor

[0084] 36 branches

[0085] 38 Third DC voltage interface

[0086] 40 Disconnecting switch

[0087] 42. Safety device (reconnect)

[0088] 44 Bridging connection

[0089] 46 Shorting element

[0090] 48 Protective Components

[0091] 50 Pre-charging device

[0092] 52 Precharge

[0093] UW AC voltage

[0094] UG DC voltage

Claims

1. A test field (2) for a bipolar test piece (4), the test field being used to electrically test the test piece (4) under a DC voltage (UG) by means of a high power of electricity that can be fed into and / or extracted from the test piece. - The test field has at least one energy source (12). - in, Each of the energy sources (12) includes a generator (14) for alternating current (UW) voltage and an inverter (16) connected to the generator (14), the inverter having at least one bipolar first DC voltage interface (18) on its side opposite to the generator (14). - The test field has multiple bipolar test stations (20) for one of the test pieces (4). - Each of the test stations (20) includes a resonant converter (22) with a bipolar second DC voltage interface (26) and a buck chopper (24) connected to the resonant converter (22) and having a bipolar DC voltage connection (28) for each test piece (4) on the side opposite to the resonant converter (22). - The test field has a modular DC voltage bus (30) that includes a series circuit of at least two DC splitters (34). - Each DC distributor (34) includes a bipolar bus (32) that can be connected in series, and includes at least two bipolar branches (36) connected to the bus (32), the branches leading from the bus (32) to their respective bipolar third DC voltage interfaces (38), wherein each branch (36) includes a bipolar disconnect switch (40). - wherein each of the first DC voltage interfaces (18) and each of the second DC voltage interfaces (26) is connected to one of the third DC voltage interfaces (38).

2. The test field (2) according to claim 1. Its features are, At least one of the disconnecting switches (40) has a safety device (42) to prevent reconnection.

3. The test field (2) according to any one of the preceding claims. Its features are, At least one of the branches (36) includes a bridging connection (44) on at least one pole that separates the connection between the bus (32) and the third DC voltage interface (38), wherein the shorting element (46) of the test field or the electrical protection element (48) of the test field can be selectively mounted in the bridging connection in a bridging manner.

4. The test field (2) according to any one of the preceding claims. Its features are, The test field (2) includes a pre-charging device (50) that can be selectively connected to one of the test stations (20) and is configured to feed pre-charge (52) into the currently connected test station (20).

5. The test field (2) according to any one of the preceding claims. Its features are, At least one of the energy sources (12) has multiple first DC voltage interfaces (18).

6. The test field (2) according to any one of the preceding claims. Its features are, All DC distributors (34) are implemented in the same way.

7. The test field (2) according to any one of the preceding claims. Its features are, The test field (2) contains at least two energy sources (12).

8. The test field (2) according to claim 7. Its features are, At least two of the energy sources (12) are connected to two different DC distributors (34).

9. The test field (2) according to any one of the preceding claims. Its features are, At least one of the DC distributors (34) is not connected to an energy source (12).

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