Dc-dc converter device and method for operating a dc-dc converter device
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SCHAEFFLER TECHNOLOGIES AG & CO KG
- Filing Date
- 2024-08-08
- Publication Date
- 2026-06-17
Smart Images
Figure EP2024072526_13022025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] DC-DC converter device and method for operating a DC-DC converter device
[0003] The present invention relates to a DC-DC converter device, in particular for a battery system, and more particularly for a battery system used as a drive unit for a vehicle, in particular in the automotive sector. The present invention further relates to a method for operating such a DC-DC converter device.
[0004] DC-DC converters convert DC voltage to DC voltage. Such devices are used particularly in the automotive sector and in the context of electromobility, for example, to convert a high-voltage DC voltage, such as that provided by a vehicle's traction battery, into a low-voltage DC voltage, such as that used in the vehicle's electrical system. Such high-voltage DC voltages are typically in the range of several hundred V, e.g., 400 V, 800 V, 1000 V, or higher. Such low-voltage voltages are typically in the range of 12 V, 14 V, 24 V, 48 V, or 64 V.
[0005] Particularly in the automotive sector and in the context of autonomously operated vehicles, it is necessary to operate low-voltage loads or low-voltage consumers, which are used, for example, in the vehicle's electrical system, in a fail-safe manner.
[0006] The object of the present invention is therefore to provide a DC-DC converter device that enables increased reliability when operating low-voltage consumers, particularly in the on-board electrical system of a vehicle. Furthermore, it is an object of the present invention to provide a method for operating such a device. These objects are achieved by the subject matter of claims 1, 9, 10, and 11. Further embodiments of the present invention are the subject matter of the dependent claims.
[0007] According to a first aspect of the present invention, a DC-DC converter device for a battery system, in particular for a traction battery system of a vehicle, is provided. The DC-DC converter device according to the invention comprises: a first DC-DC converter with a high-voltage side and a low-voltage side, wherein the high-voltage side has a first and a second high-voltage connection and the low-voltage side has a first and a second low-voltage connection;a switching matrix with a first switch designed to connect a positive terminal of a first battery unit of the battery system to the first high-voltage terminal of the first DC-DC converter, a second switch designed to connect a positive terminal of a second battery unit of the battery system to the first high-voltage terminal of the first DC-DC converter, a third switch designed to connect a negative terminal of the first battery unit to the second high-voltage terminal of the first DC-DC converter, a fourth switch designed to connect a negative terminal of the second battery unit to the second high-voltage terminal of the first DC-DC converter;and a control unit which is connected to at least the first to fourth switches of the switching matrix and is designed, in the event of a fault in one of the two battery units, to actuate the switches of the switching matrix such that the battery unit affected by the fault is disconnected from the first DC-DC converter, the positive terminal of the battery unit not affected by the fault is connected to the first high-voltage terminal of the first DC-DC converter, and the negative terminal of the battery unit not affected by the fault is connected to the second high-voltage terminal of the first DC-DC converter.;
[0008] In the context of this disclosure, the term “switch” is understood to mean a unit with which it is possible to selectively disconnect and reconnect an electrical connection in a controlled manner. In the context of this disclosure, such switches can be, for example, relays, MOSFETs or the like. In the context of this disclosure, the term “fault tolerance” is understood to mean that the battery unit affected by the fault cannot be operated as desired, i.e. not in the normal case. Fault cases can be, for example: the battery is too hot, too cold, too old, too discharged, the battery has too high a voltage, etc. Fault cases can also be: a missing electrical connection technology to and from the respective battery unit or between battery units and / or a fault in the battery management system and / or an error output by the battery management system.
[0009] The DC-DC converter device according to the invention is based at least in part on the recognition that, particularly to increase reliability when supplying low-voltage loads, precautions must be taken that can at least partially or completely mitigate the faults described above. In particular, the present invention is based on the recognition that a fault in a battery unit of a battery system, which may be, for example, the traction battery system of a vehicle, must be mitigated in order to ensure, for example, a sufficient supply to the on-board electrical system and, in particular, a sufficient supply to low-voltage consumers of the on-board electrical system.The present invention proposes compensating for a fault in, for example, a battery unit of the battery system by connecting the battery units to the DC-DC converter and to a control unit via a switching matrix, wherein the control unit detects a fault in the battery unit and actuates the switches of the switching matrix accordingly such that the fault can be rectified. In particular, the invention proposes that the fault in one of the battery units can be rectified by disconnecting the battery unit affected by the fault from the DC-DC converter (in particular by actuating the corresponding switches of the switching matrix) and connecting the battery unit not affected by the fault to the DC-DC converter or leaving it connected.This arrangement allows the battery unit not affected by the fault to be used to supply the low-voltage consumers of the vehicle's electrical system in the event of a fault. This increases reliability during operation.
[0010] Low-voltage consumers.
[0011] In a further embodiment of the present invention, the switching matrix further comprises a first additional switch designed to connect a positive terminal of a third battery unit of the battery system to the first high-voltage terminal of the first DC-DC converter, and the switching matrix further comprises a second additional switch designed to connect a negative terminal of the third battery unit to the second high-voltage terminal of the first DC-DC converter. This embodiment is based at least in part on the realization that multiple, in particular third or further, battery units of a battery system can be connected in an analogous manner to the same DC-DC converter. Each positive terminal of each battery unit and each negative terminal of the corresponding battery unit can be connected to the respective high-voltage terminal of the DC-DC converter by means of the switches of the switching matrix.
[0012] In a further embodiment of the present invention, the DC-DC converter device further comprises: a second DC-DC converter with a high-voltage side and a low-voltage side, wherein the high-voltage side has a first and a second high-voltage connection and the low-voltage side has a first and a second low-voltage connection, and wherein the low-voltage connections of the second DC-DC converter are connected in parallel to the low-voltage connections of the first DC-DC converter, wherein the switching matrix further comprises: a fifth switch designed to connect the positive connection of the second battery unit to the first high-voltage connection of the second DC-DC converter, a sixth switch designed to connect the positive connection of the first battery unit to the first high-voltage connection of the second DC-DC converter, a seventh switch,which is designed to connect the negative terminal of the second battery unit to the second high-voltage terminal of the second DC-DC converter, and an eighth switch which is designed to connect the negative terminal of the first battery unit to the second high-voltage terminal of the second DC-DC converter, wherein the control unit is further connected to the fifth to eighth switches of the switching matrix and is designed, in the event of a fault in one of the two battery units, to actuate the switches of the switching matrix such that the battery unit affected by the fault is disconnected from the first and second DC-DC converter,the positive terminal of the battery unit not affected by the fault is connected to the first high-voltage terminal of the first DC-DC converter and to the first high-voltage terminal of the second DC-DC converter, and the negative terminal of the battery unit not affected by the fault is connected to the second high-voltage terminal of the first DC-DC converter and to the second high-voltage terminal of the second DC-DC converter.
[0013] The present invention is initially based in part on the realization that instead of a single DC-DC converter and four switches to rectify a fault, the fault in one of the battery units can also be compensated for if the device has a switching matrix with eight switches and two DC-DC converters. The two DC-DC converters are connected in parallel on the low-voltage side, so that the output powers of the DC-DC converters are added together. This has the advantage that instead of one DC-DC converter, which is designed, for example, for 8 kW normal operation and still delivers 4 kW in the event of a fault in which one of the two battery units fails, it can be replaced by two 2 kW DC-DC converters, which jointly deliver 4 kW in normal operation and in the event of a fault. In concrete terms, for example:Normally, each of the battery units is connected to an associated DC-DC converter via the respective switches, so that the output power of the DC-DC converters is added together (e.g. 2kW output power from the first DC-DC converter is added together with the 2kW output power from the second DC-DC converter). If one of the battery units has a fault, the control unit detects this and activates the switches in the switching matrix so that the battery unit not affected by the fault is connected to both the one and the other DC-DC converter. The total output power on the low-voltage side remains at 2kW from the first DC-DC converter plus 2kW from the second DC-DC converter. The total output power therefore does not change compared to the normal case. The cost of the four additional switches in the switching matrix is offset by the fact that the two DC-DC converters, for example,only need to be designed for 2 kW, whereas a single DC-DC converter (plus 4 switches instead of 8) would have to be designed for 8 kW to provide 4 kW of power to the on-board network even in the event of a fault. In this respect, the arrangement with two DC-DC converters and four additional switches in the switching matrix proves advantageous. The two DC-DC converters can be separate DC-DC converters, each with its own controller in its own housing, or they can be two phases of a DC-DC converter arranged in a common housing.
[0014] Preferably, the low-voltage side of the first DC-DC converter can be interruptibly connected to a low-voltage load or to a low-voltage consumer by means of a disconnect switch.
[0015] In the case of two DC-DC converters, it is particularly advantageous if the low-voltage side of the first DC-DC converter can be interruptibly connected to a low-voltage load or a low-voltage consumer by means of a first isolating switch, and the low-voltage side of the second DC-DC converter can be interruptibly connected to a low-voltage load or a low-voltage consumer by means of a second isolating switch, and the control unit is further configured to actuate the first and / or second isolating switch such that, depending on the power required by the low-voltage load, the first DC-DC converter and / or the second DC-DC converter is connected to the low-voltage load. This embodiment is based at least in part on the realization that each of the DC-DC converters can be connected to the low-voltage network via a corresponding isolating switch and can be switched on or off as needed. The isolating switches can be contactors.In a preferred embodiment, the battery units of the battery system are connected in series, in particular connected in series without switches, and the switching matrix is further designed to connect the positive terminal of the first battery unit to the first high-voltage terminal of the first DC-DC converter and the negative terminal of the second battery unit to the second high-voltage terminal of the DC-DC converter. The connection is made in particular as a function of a voltage that can be provided by the battery unit(s). For example, the control unit can determine whether a voltage that can be provided by one or more battery units is below a threshold value and then actuate the switches of the switching matrix such that the positive terminal of the first battery unit and the negative terminal of the second battery unit are connected to the high-voltage terminals of the first DC-DC converter.
[0016] In a further preferred embodiment, the battery units are connected in series, in particular connected in series without switches, and the switches of the switching matrix, in particular the second switch, the third switch and the fifth switch, can each be connected to a center tap between the battery units.
[0017] In a further embodiment of the present invention, the DC-DC converter device further comprises: a third DC-DC converter with a high-voltage side and a low-voltage side, wherein the high-voltage side has a first and a second high-voltage connection and the low-voltage side has a first and a second low-voltage connection, and wherein the low-voltage connections of the third DC-DC converter are connected in parallel to the low-voltage connections of the second DC-DC converter and the low-voltage connections of the first DC-DC converter, and wherein the switching matrix further comprises: a ninth switch designed to connect the positive connection of the first battery unit to the first high-voltage connection of the third DC-DC converter, a tenth switch designed to connect the positive connection of the second battery unit to the first high-voltage connection of the third DC-DC converter, an eleventh switch,which is designed to connect the negative terminal of the first battery unit to the second high-voltage terminal of the third DC-DC converter, and a twelfth switch which is designed to connect the negative terminal of the second battery unit to the second high-voltage terminal of the third DC-DC converter, wherein the control unit is further connected to the ninth to twelfth switches of the switching matrix and is designed, in the event of a fault in the first DC-DC converter or the second DC-DC converter, to actuate the switches of the switching matrix such that the DC-DC converter affected by the fault is disconnected from the battery units and a DC-DC conversion of the DC-DC converter affected by the fault is taken over by the third DC-DC converter as needed.
[0018] This design is based, at least in part, on the realization that a further fault in one of the two DC-DC converters can be compensated for by a third or additional DC-DC converter. The third DC-DC converter is connected to the two battery units in a similar way to the first DC-DC converter and the second DC-DC converter. In such a case, the switching matrix has four additional switches, with which each of the battery units can be connected to the two high-voltage terminals of the third DC-DC converter. The third DC-DC converter replaces the defective DC-DC converter in terms of function and application. This allows both normal operation (e.g., all battery units operate faultlessly) to be maintained despite a defective DC-DC converter, and a fault in one of the battery units to be compensated for.Failure tolerance is further increased because now not only a fault in one of the battery units, but also a fault in one of the DC-DC converters can be intercepted. Ultimately, the third DC-DC converter functions as a backup DC-DC converter for one of the two DC-DC converters. According to a further aspect of the present invention, a method for operating a DC-DC converter device according to the first aspect is proposed.The method comprises the steps of: determining a fault in one of the battery units of the battery system, and controlling the switches of the switching matrix such that the battery unit affected by the fault is disconnected from the first DC-DC converter, the positive terminal of the battery unit not affected by the fault is connected to the first high-voltage terminal of the first DC-DC converter, and the negative terminal of the battery unit not affected by the fault is connected to the second high-voltage terminal of the first DC-DC converter.
[0019] A further aspect of the present invention provides a method for operating a DC-DC converter device with, in particular, at least two battery units and two DC-DC converters, the method comprising the following steps: detecting a fault in one of the battery units of the battery system, and controlling the switches of the switching matrix such that the battery unit affected by the fault is disconnected from the first DC-DC converter and from the second DC-DC converter,the positive terminal of the battery unit not affected by the fault is connected to the first high-voltage terminal of the first DC-DC converter and to the first high-voltage terminal of the second DC-DC converter, and the negative terminal of the battery unit not affected by the fault is connected to the second high-voltage terminal of the first DC-DC converter and to the second high-voltage terminal of the second DC-DC converter.
[0020] A further aspect of the present invention provides a method for operating a DC-DC converter device with, in particular, at least two battery units and three DC-DC converters, the method comprising the following steps: determining a fault in the first DC-DC converter or in the second DC-DC converter, and controlling the switches of the switching matrix such that the DC-DC converter affected by the fault is separated from the battery units and a DC-DC conversion of the DC-DC converter affected by the fault is taken over by the third DC-DC converter if necessary.
[0021] Further features and objects of the present invention will become apparent to those skilled in the art upon application of the present teachings and upon consideration of the accompanying drawings.
[0022] FIG 1 is a schematic view of a DC-DC converter device according to an embodiment of the invention, the device comprising two battery units and a DC-DC converter,
[0023] FIG 2 is a schematic view of a DC-DC converter device according to a further embodiment of the invention, the device comprising three battery units and a DC-DC converter,
[0024] FIG 3 is a schematic view of a DC-DC converter device according to a further embodiment of the invention, the device comprising two battery units and two DC-DC converters.
[0025] FIG 4 is a schematic view of a DC-DC converter device according to a further embodiment of the invention, the device comprising two battery units and three DC-DC converters.
[0026] Elements with the same function or construction are provided with the same reference symbols throughout the figures.
[0027] Reference is first made to FIG. 1, which shows a schematic view of an embodiment of a DC-DC converter device 10. The DC-DC converter device 10 serves to convert a high-voltage DC voltage, which is provided, for example, by a battery system 12, into a low-voltage DC voltage. The battery system 12 can be, for example, a traction battery system of a vehicle. In the specific example of FIG. 1, the battery system 12 has a first battery unit 14 and a second battery unit 16. In the specific example of FIG. 1, both battery units 14, 16 are connected in series. This need not be the case in other embodiments shown.
[0028] The DC-DC converter device 10 further comprises a DC-DC converter 18. The DC-DC converter 18 serves to convert DC voltage. For this purpose, the DC-DC converter 18 has a high-voltage side HV and a low-voltage side LV. The high-voltage side has two high-voltage connections 20, of which a first high-voltage connection is provided with the reference numeral 22 and a second high-voltage connection is provided with the reference numeral 24. The low-voltage side has two low-voltage connections 26, of which a first low-voltage connection is provided with the reference numeral 28 and a second low-voltage connection is provided with the reference numeral 30. The low-voltage connections 26 serve for connection to a low-voltage load or a low-voltage consumer, which is indicated by way of example in FIG. 1 with the reference numeral 32.Such a low-voltage consumer can, for example, be a low-voltage consumer of a vehicle's electrical system, such as a seat heater, a multimedia system, an air conditioning system, a driver assistance system or the like.
[0029] The DC-DC converter device 10 further includes a switching matrix 34. The switching matrix 34 serves to connect the high-voltage terminals 22, 24 of the DC-DC converter 18 to the battery units 14, 16 of the battery system 12. The switching matrix 34 includes several switches. In the specific example of FIG. 1, the switching matrix includes four switches S1 to S4, the function of which will be described in more detail later.
[0030] The DC-DC converter device 10 further comprises a control unit 36. The control unit 36 is connected to the switching matrix 34 and in particular to the switches of the switching matrix 34 and is designed to actuate the switches of the switching matrix 34 as needed. In the specific example in FIG. 1, the first switch S1 of the switching matrix 34 is arranged or designed such that a positive terminal of the first battery unit 14 of the battery system 12 can be connected to the first high-voltage terminal 22 of the DC-DC converter 18. In the specific example in FIG. 1, the second switch S2 of the switching matrix 34 is arranged or designed such that a positive terminal of the second battery unit 16 of the battery system 12 can be connected to the first high-voltage terminal 22 of the DC-DC converter 18. In the specific example in FIG. 1, the third switch S3 is arranged or designed such thatdesigned such that a negative terminal of the first battery unit 14 of the battery system 12 can be connected to the second high-voltage terminal 24 of the DC-DC converter 18. Finally, in the specific example of FIG. 1, the fourth switch S4 of the switching matrix 34 is arranged or designed such that a negative terminal of the second battery unit 16 of the battery system 12 can be connected to the second high-voltage terminal 24 of the DC-DC converter 18.
[0031] The control unit 36 is now connected to the switches S1 to S4 of the switching matrix 34 such that, in the event of a fault in one of the two battery units, the switches S1 to S4 of the switching matrix 34 are actuated such that the faulty battery unit is disconnected from the DC-DC converter 18, the positive terminal of the battery unit not affected by the fault is connected to the first high-voltage terminal 22 of the DC-DC converter 18, and the negative terminal of the battery unit not affected by the fault is connected to the second high-voltage terminal 24 of the DC-DC converter 18. In other words: If, for example, the second battery unit 16 is faulty or has a fault, the control unit 36 actuates the switches S1 and S3 such that the positive and negative terminals of the first battery unit 14 are connected to the high-voltage terminals 20 of the DC-DC converter 18.In other words, in such a case, the first switch S1 and the third switch S3 are closed. Furthermore, the control unit 36 actuates the switches S2 and S4 such that the second battery unit 16, i.e., the faulty battery unit, is disconnected from the DC-DC converter 18. In other words, in such a case, the second switch S2 and the fourth switch S4 are open.
[0032] The control unit detects which battery unit of the battery system 12 is faulty and switches the switches S1 to S4 such that the battery unit not affected by the fault is connected to the high-voltage terminals 20 of the DC-DC converter 18. As a result, the low-voltage consumer 32 or the low-voltage load 32 can be supplied with power, which, if necessary (i.e., depending on the fault situation), is provided either by the first battery unit 14 or by the second battery unit 16.
[0033] Furthermore, the control unit 36 is also designed to actuate the switches of the switching matrix 34 such that the positive terminal of the first battery unit 14 is connected to the first high-voltage terminal 22 of the first DC-DC converter 18, and the negative terminal of the second battery unit 16 is connected to the second high-voltage terminal 24 of the first DC-DC converter. The connection of the battery units 14, 16 arranged in series can be effected in particular depending on one or more factors. For example, the control unit 16 can determine whether an (output) voltage that can be provided by the respective battery unit is below a threshold value and, in response to the voltage falling below the threshold value, connect the battery units 14, 16 arranged in series accordingly to the high-voltage terminals 22, 24.Specifically, the control unit 36 would close the switches S1 and S4 and the control unit 36 would open the switches S2 and S3 in order to connect the two battery units 14, 16 in series arrangement to the high-voltage terminals 20 of the DC-DC converter.
[0034] In the specific example of FIG. 1, a disconnect switch S201 is also arranged between the low-voltage load 32 and the low-voltage side LV of the DC-DC converter 18. The disconnect switch S201 can also be connected to the control unit 36 and serves to interruptibly connect the low-voltage side LV of the DC-DC converter to the low-voltage load 32. The disconnect switch S201 can be a contactor, for example. The switches of the switching matrix can be relays, MOSFETs, or the like.
[0035] Reference is now made to FIG. 2, which shows a further embodiment of the DC-DC converter device 10 according to the invention.
[0036] In the specific example of FIG. 2, the battery system 12 comprises three battery units 14, 16, 38. In the specific example of FIG. 2, the three battery units 14, 16, 38 are connected in series, but may also be arranged differently in other embodiments not shown.
[0037] In the specific example of FIG 2, the third battery unit 38 is connected to the low-voltage terminals 20 of the DC-DC converter 18 in a similar way to the first battery unit 14 or second battery unit 16. Specifically, the switching matrix 34 has a first additional switch S22, which is arranged or designed such that a positive terminal of the third battery unit 38 of the battery system 12 can be connected to the first high-voltage terminal 22 of the DC-DC converter 18, and the switching matrix 34 has a second additional switch S42, which is arranged or designed such that a negative terminal of the third battery unit 38 of the battery system 12 can be connected to the second high-voltage terminal 24 of the DC-DC converter 18.
[0038] In the specific example of FIG 2, the third battery unit is connected in such a way that it can compensate for a fault in one of the two battery units 14, 16. If, for example, the second battery unit 16 is faulty, this fault can be compensated for by the third battery unit 38. The control unit 36 is connected to the switching matrix 34 and the additional switches S22, S42 and can actuate them accordingly depending on the application. If, for example, the second battery unit 16 is faulty, the control unit 36 actuates the switches S2 and S4 such that the second battery unit 16 is disconnected from the DC-DC converter. Furthermore, the control unit 36 actuates the additional switches S22 and S42 such that the third battery unit 38 is connected to the high-voltage terminals 20 of the DC-DC converter 18.In other words, in the event of a fault in the second battery unit 16, switches S2 and S4 are opened and switches S22 and S42 are closed. The DC-DC converter device 10 thus makes it possible to supply low-voltage loads 32 with power from one of the three and / or two of the three battery units 14, 16, 38, if necessary.
[0039] Reference is now made to FIG. 3, which shows a further embodiment of the DC-DC converter device 10.
[0040] In the DC-DC converter device 10 according to FIG. 3, the DC-DC converter device 10 has, in addition to the first DC-DC converter 18, a second DC-DC converter 40. These can be separate DC-DC converters or two phases of a DC-DC converter arranged in a single housing, schematically indicated by box 41.
[0041] The second DC-DC converter has a high-voltage side HV with a first high-voltage connection 42 and a second high-voltage connection 44, as well as a low-voltage side LV with a first low-voltage connection 46 and a second low-voltage connection 48. The second DC-DC converter 40 and the first DC-DC converter 18 are connected in parallel on the low-voltage side, so that the output powers of the DC-DC converters 18, 40 can be added together.
[0042] In the specific example of FIG. 3, the switching matrix 34 has four additional switches S5 to S8. The four additional switches are used to connect the two battery units 14, 16 of the battery system 12 to the second DC-DC converter 40.
[0043] Specifically, the switching matrix 34 has a fifth switch S5, which is arranged or designed to connect a positive terminal of the second battery unit 16 of the battery system 12 to the first high-voltage terminal 42 of the second DC-DC converter 40. Specifically, the switching matrix 34 in the embodiment of FIG 3 has a sixth switch S6, which is arranged or designed to connect the positive terminal of the first battery unit 14 of the battery system 12 to the first high-voltage terminal 42 of the second DC-DC converter 40. Specifically, the switching matrix 34 in the embodiment of FIG 3 has a seventh switch S7, which is arranged or designed to connect the negative terminal of the second battery unit 16 of the battery system 12 to the second high-voltage terminal 44 of the second DC-DC converter 40.Finally, in the specific example of FIG. 3, the switching matrix 34 has an eighth switch which is arranged or designed to be able to connect the negative terminal of the first battery unit 14 of the battery system 14 to the second high-voltage terminal 44 of the second DC-DC converter 40.
[0044] In the concrete example of FIG 3, the control unit 36 is connected to the switching matrix 34 and its switches S1 to S8 in such a way that it can actuate the switches S1 to S8 accordingly if necessary.
[0045] For example, if no fault occurs in the battery system 12 or both battery units 14, 16 are operating normally, the control unit 36 actuates the switches S1, S3 such that the first battery unit 14 is connected to the first DC-DC converter 18. Specifically, the switches S1 and S3 are closed. Furthermore, the control unit 36 can actuate the switches S2 and S4 such that the second battery unit 16 is disconnected from the first DC-DC converter 18. Specifically, the switches S2 and S4 would be opened. Furthermore, the control unit 36 actuates the switches S5 and S7 such that the second battery unit 16 is connected to the high-voltage terminals 42, 44 of the second DC-DC converter 40. Specifically, the switches S5 and S7 are closed. Furthermore, the control unit 36 can actuate the switches S6 and S8 such that the first battery unit 14 is disconnected from the high-voltage terminals 42, 44 of the second DC-DC converter 40.Specifically, switches S6 and S8 would be opened. This switching arrangement now supplies the first DC-DC converter 18 with voltage from the first battery unit 14, and the second DC-DC converter 40 with voltage from the second battery unit 16. For example, if the two DC-DC converters 18, 40 are each designed for 2 kW output power, the low-voltage load 32 could normally be supplied with 4 kW.
[0046] If a fault occurs in one of the two battery units 14, 16 of the battery system 12, the control unit 36 can actuate the switches S1 to S8 of the switching matrix 34 in such a way that the faulty battery unit is disconnected from the DC-DC converters 18, 40 and yet 4 kW is still available to supply the low-voltage load 32.
[0047] In the specific example, it is assumed that the second battery unit 16 is faulty or that a fault occurs in the second battery unit 16.
[0048] The control unit 36 detects this fault and actuates switches S1 to S8 of the switching matrix 34 accordingly. Specifically, the control unit 36 actuates switches S2, S4, S5, and S7 such that the battery unit experiencing the fault—in this example, the second battery unit 16 of the battery system 12—is disconnected from the two DC-DC converters 18, 40. Specifically, switches S2, S4, S5, and S7 are opened. Furthermore, the control unit 36 actuates switches S6, S8 of the switching matrix 34 such that the first battery unit 14, the battery unit not experiencing a fault, is connected to the first and second DC-DC converters 18, 40. Specifically, switches S1 and S3, as well as S6 and S8, are closed. Through this switching arrangement, the first DC-DC converter 18 is now supplied with voltage by the first battery unit 14 and the second DC-DC converter 40 is supplied with voltage by the first battery unit 14.Since the two DC-DC converters 18, 40 are connected in parallel on the low-voltage side, the low-voltage consumer 32 can be supplied with a total of 4 kW output power even in the event of a fault in the second battery unit 16.
[0049] As already described in connection with FIG. 2, both the first DC-DC converter 18 and the second DC-DC converter 14 are interruptibly connected to the low-voltage load 32 by means of a first isolating switch S201 and a second isolating switch S202, respectively. The control unit 36 can be connected to the isolating switches S201, S202 and, if necessary, can selectively disconnect the DC-DC converters 18, 14 from the low-voltage load 32.
[0050] Reference is made to FIG 4, which shows a further embodiment of the DC-DC converter device 10.
[0051] In the embodiment of FIG 4, the DC-DC converter device 10 has a third DC-DC converter 50. The third DC-DC converter 50 also has a high-voltage side HV with a first high-voltage connection 52 and a second high-voltage connection 54, as well as a low-voltage side LV with a first low-voltage connection 56 in a second low-voltage connection 58.
[0052] In the specific example of FIG. 4, the switching matrix 34 has four additional switches S9 to S12. Switches S9 to S12 serve to connect the positive or negative terminals of the respective battery units 14, 16 of the battery system 12 to the high-voltage terminals 52, 54, depending on the requirements.
[0053] The control unit 36 is connected to the switching matrix 34 and to the switches S1 to S12 of the switching matrix 34 and can actuate the switches S1 to S12 accordingly if necessary.
[0054] The third DC-DC converter 50 is connected on the low-voltage side LV in parallel with the first DC-DC converter 18 and the second DC-DC converter 40. The third DC-DC converter 50 serves as a backup DC-DC converter for one of the two DC-DC converters 18, 40. Each of the DC-DC converters 18, 40, 50 is interruptibly connected to the low-voltage load 32 by means of a disconnect switch S201, S202, S203.
[0055] If the battery system 12 is operating correctly or the battery units 14, 16 are not experiencing any faults, the third, redundant DC-DC converter 50 is disconnected from the battery units 14, 16. Specifically, the control unit 36 actuates switches S9 to S12 so that they are open. The remaining switches S1 to S8 are actuated by the control unit 36 as described in connection with FIG. 3.
[0056] However, if one of the two DC-DC converters 18, 40 has a fault, the control unit 36 registers this fault and actuates the switches S1 and S12 accordingly in order to decouple the DC-DC converter 18, 40 with the fault from the battery units 14, 16 and to use the third DC-DC converter 50 instead of the DC-DC converter with the fault.
[0057] In the following, it is assumed that the second DC-DC converter 40 is faulty or has a fault condition.
[0058] If the second DC-DC converter 40 is faulty, the control unit 36 controls switches S1 to S12 such that the third DC-DC converter 50 takes over the function of the second DC-DC converter 40. Specifically, the control unit 34 actuates switches S5 to S8 such that the second DC-DC converter 40, i.e., the faulty DC-DC converter, is disconnected from the battery units 14, 16. Specifically, the control unit 16 opens switches S4 to S8. Furthermore, the control unit 36 actuates switches S1 and S3 and switches S2 and S4 such that the first battery unit 14 is connected to the first DC-DC converter 18, the DC-DC converter not affected by the fault. Specifically, the control unit 36 closes switches S1 and S3 and opens switches S2 and S4.Furthermore, the control unit 36 actuates the switches S9 and S11 and the switches S10 and S12 such that the second battery unit 16 is now connected not to the second DC-DC converter 40, but to the third DC-DC converter 50. Specifically, the control unit 36 opens the switches S9 and S11 and closes the switches S10 and S12. In other words, the switches S10 and S12 take over the function of the switches S5 and S7, and the switches S9 and S11 take over the function of the switches S6 and S8. Thus, instead of the second DC-DC converter 40, the third DC-DC converter 50 is supplied with voltage from the second battery unit 16, and the first DC-DC converter 18 is supplied with voltage from the first battery unit 14.
[0059] If all three DC-DC converters 18, 40, 50 are designed the same, for example for 2kW output power each, the low-voltage consumer 32 would still be able to be supplied with 4kW of power in the event of a defective second DC-DC converter 40, since the 2kW output power of the first DC-DC converter 18 is added to the 2kW output power of the third DC-DC converter 50.
[0060] The third DC-DC converter 50 is thus a backup DC-DC converter for one of the DC-DC converters 18, 40 in the event of a fault in one of the two DC-DC converters 18, 40.
[0061] If none of the battery units 14 or 16 are faulty, the low-voltage consumer 32 can thus be operated with the two DC-DC converters 18 and 50 instead of the DC-DC converters 18 and 40.
[0062] In the following, it is assumed that in addition to the second DC-DC converter 40, the second battery unit 16 is now also faulty.
[0063] If the second battery unit 16 is faulty, this is registered by the control unit 36. The control unit 36 actuates the switching matrix 34 and its switches S1 and S12 accordingly to disconnect the faulty battery unit 16 of the battery system 12 from the DC-DC converters 18, 40, 50. Specifically, the control unit 36 opens the switches S2, S4, S10, S12. Switches S5 to S8 are already open due to the fact that it was assumed that the second DC-DC converter 40 is defective. Furthermore, the control unit 36 actuates the switches S1 and S3 and the switches S2 and S4 so that the first battery unit 14 is connected to the first DC-DC converter 18. Specifically, the control unit 36 closes the switches S1 and S3.
[0064] Furthermore, the control unit 36 actuates the switches S9 and S11, so that the first battery unit 14, i.e., the battery unit not affected by the fault, is also connected to the third DC-DC converter 50. Specifically, the control unit 36 closes the switches S9 and S11.
[0065] This arrangement ensures that both the first DC-DC converter 18 and the third DC-DC converter 50 are supplied with voltage by the battery unit 14 not affected by the fault. By connecting the first DC-DC converter 18 and the third DC-DC converter in parallel on the low-voltage side, the output powers of the DC-DC converters 18, 50 are added together, and the low-voltage load 32 can continue to be supplied with the desired output power, in this example, 4 kW.
[0066] Of course, further combinations of switches S1 to S12 are conceivable, depending on the application and arrangement.
[0067] Of course, the application cases described in connection with FIGS 1 to 4 can be combined in any meaningful way to catch other error cases in the system.
[0068] In other embodiments not shown, the DC-DC converter device 10 can have further battery units and / or further DC-DC converters in order to absorb further faults as needed, so that the reliability of the supply to the low-voltage consumer 32 can be further increased.
Claims
Patent claims 1 . DC-DC converter device (10) for a battery system (12), comprising: a first DC-DC converter (18) with a high-voltage side and a low-voltage side, wherein the high-voltage side has a first and a second high-voltage connection (22, 24) and the low-voltage side has a first and a second low-voltage connection (28, 30), a switching matrix (34) with - a first switch (S1) designed to connect a positive terminal of a first battery unit (14) of the battery system (12) to the first high-voltage terminal (22) of the first DC-DC converter (18), - a second switch (S2) designed to connect a positive terminal of a second battery unit (16) of the battery system (12) to the first high-voltage terminal (22) of the first DC-DC converter (18), - a third switch (S3) designed to connect a negative terminal of the first battery unit (14) to the second high-voltage terminal (24) of the first DC-DC converter (18), - a fourth switch (S4) which is designed to connect a negative terminal of the second battery unit (16) to the second high-voltage terminal (24) of the first DC-DC converter (18), and a control unit (36) which is connected to the first to fourth switches (S1 - S4) of the switching matrix (34) and is designed, in the event of a fault in one of the two battery units (14, 16), to actuate the switches (S1 - S4) of the switching matrix (34) in such a way that the battery unit (14, 16) affected by the fault is separated from the first DC-DC converter (18), the positive terminal of the battery unit (14, 16) not affected by the fault is connected to the first high-voltage terminal (22) of the first DC-DC converter (18), and the negative terminal of the battery unit not affected by the fault Battery unit (14, 16) is connected to the second high-voltage connection (24) of the first DC-DC converter (18).
2. DC-DC converter device (10) according to claim 1, wherein the low-voltage side of the first DC-DC converter (18) can be interruptibly connected to a low-voltage load (32) by means of a circuit breaker (S201).
3. DC-DC converter device (10) according to one of the preceding claims, further comprising: a second DC-DC converter (40) having a high-voltage side and a low-voltage side, wherein the high-voltage side has a first and a second high-voltage terminal (42, 44) and the low-voltage side has a first and a second low-voltage terminal (46, 48), and wherein the low-voltage terminals (46, 48) of the second DC-DC converter (40) are connected in parallel to the low-voltage terminals (28, 30) of the first DC-DC converter (18), wherein - the switching matrix (34) further comprises - a fifth switch (S5) designed to connect the positive terminal of the second battery unit (16) to the first high-voltage terminal (42) of the second DC-DC converter (40), - a sixth switch (S6) designed to connect the positive terminal of the first battery unit (14) to the first high-voltage terminal (42) of the second DC-DC converter (40), - a seventh switch (S7) designed to connect the negative terminal of the second battery unit (16) to the second high-voltage terminal (44) of the second DC-DC converter (40), and - an eighth switch (S8) which is designed to connect the negative terminal of the first battery unit (14) to the second high-voltage terminal (44) of the second DC-DC converter (40), wherein - the control unit (36) is further connected to the fifth to eighth switches (S5-S8) of the switching matrix (34) and is designed, in the event of a fault in one of the two battery units (14, 16), to actuate the switches (S1-S8) of the switching matrix (34) such that the battery unit (14, 16) affected by the fault is disconnected from the first and second DC-DC converters (18, 40), the positive terminal of the battery unit (14, 16) not affected by the fault is connected to the first high-voltage terminal (22) of the first DC-DC converter (18) and to the first high-voltage terminal (42) of the second DC-DC converter (40), and the negative terminal of the battery unit (14, 16) not affected by the fault is connected to the second high-voltage terminal (24) of the first DC-DC converter (18) and to the second high-voltage terminal (44) of the second DC-DC converter (40).
4. DC-DC converter device (10) according to claim 3, wherein the low-voltage side of the first DC-DC converter (18) is interruptibly connectable to a low-voltage load (32) by means of a first isolating switch (S201) and the low-voltage side of the second DC-DC converter (40) is interruptibly connectable to a low-voltage load (32) by means of a second isolating switch (S202), and the control unit (36) is further designed to actuate the first and / or second isolating switch (S201, S202) such that the first DC-DC converter (18) and / or the second DC-DC converter (40) is / are connected to the low-voltage load (32) as a function of a power required by the low-voltage load (32).
5. DC-DC converter device (10) according to one of the preceding claims, wherein the battery units (14, 16) of the battery system (12) are connected in series and the switching matrix (34) is further designed to connect the positive terminal of the first battery unit (14) to the first high-voltage terminal (22) of the first DC-DC converter (18) and the negative terminal of the second battery unit (16) to the second high-voltage terminal (24) of the first DC-DC converter (18).
6. DC-DC converter device (10) according to one of the preceding claims, wherein the battery units (14, 16) of the battery system (12) are connected in series and at least the second, third and fifth switches (S2, S3, S5) are each connectable to a center tap between the battery units (14, 16).
7. DC-DC converter device (10) according to one of the preceding claims, wherein the switching matrix (34) further comprises a first additional switch (S22) which is designed to connect a positive terminal of a third battery unit (38) of the battery system (12) to the first high-voltage terminal (22) of the first DC-DC converter (18), and a second additional switch (S42) which is designed to connect a negative terminal of the third battery unit (38) to the second high-voltage terminal (24) of the first DC-DC converter (18).
8. DC-DC converter device (10) according to one of claims 3 to 7, further comprising: a third DC-DC converter (50) having a high-voltage side and a low-voltage side, wherein the high-voltage side has a first and a second high-voltage terminal (52, 54) and the low-voltage side has a first and a second low-voltage terminal (56, 58), and wherein the low-voltage terminals (56, 58) of the third DC-DC converter (50) are connected in parallel to the low-voltage terminals (46, 48) of the second DC-DC converter (40) and to the low-voltage terminals (28, 30) of the first DC-DC converter (18), and wherein - the switching matrix (34) further comprises - a ninth switch (S9) designed to connect the positive terminal of the first battery unit (14) to the first high-voltage terminal (52) of the third DC-DC converter (50), - a tenth switch (S10) for connecting the positive terminal of the second battery unit (16) to the first High-voltage connection (52) of the third DC-DC converter (50) is formed, - an eleventh switch (S11) designed to connect the negative terminal of the first battery unit (14) to the second high-voltage terminal (54) of the third DC-DC converter (50), and - a twelfth switch (S12) which is designed to connect the negative terminal of the second battery unit (16) to the second high-voltage terminal (54) of the third DC-DC converter (50), wherein the control unit (36) is further connected to the ninth to twelfth switches (S9-S12) of the switching matrix (34) and is designed, in the event of a fault in the first DC-DC converter (18) or the second DC-DC converter (40), to actuate the switches (S1-S12) of the switching matrix (34) in such a way that the DC-DC converter (18, 40) affected by the fault is separated from the battery units (14, 16) and a DC-DC conversion of the DC-DC converter (18, 40) affected by the fault is taken over by the third DC-DC converter (50) as needed.
9. A method for operating a DC-DC converter device (10) for a battery system (12) according to claim 1, comprising the steps: Determining a fault in one of the battery units (14, 16) of the battery system (12), and Controlling the switches of the switching matrix (34) in such a way that the battery unit (14, 16) affected by the fault is disconnected from the first DC-DC converter (18), the positive terminal of the battery unit (14, 16) not affected by the fault is connected to the first high-voltage terminal (22) of the first DC-DC converter (18), and the negative terminal of the battery unit (14, 16) not affected by the fault is connected to the second high-voltage terminal (24) of the first DC-DC converter (18).
10. A method for operating a DC-DC converter device (10) for a battery system (12) according to one of claims 3 to 7, comprising the steps: Determining a fault in one of the battery units (14, 16) of the battery system (12), and - controlling the switches of the switching matrix (34) in such a way that the battery unit (14, 16) affected by the fault is disconnected from the first DC-DC converter (18) and from the second DC-DC converter (40), the positive terminal of the battery unit (14, 16) not affected by the fault is connected to the first high-voltage terminal (22) of the first DC-DC converter (18) and to the first high-voltage terminal (42) of the second DC-DC converter (40), and the negative terminal of the battery unit (14, 16) not affected by the fault is connected to the second high-voltage terminal (24) of the first DC-DC converter (18) and to the second high-voltage terminal (44) of the second DC-DC converter (40).
11. A method for operating a DC-DC converter device (10) for a battery system (12) according to claim 8, comprising the steps: Determining a fault in the first DC-DC converter (18) or in the second DC-DC converter (40), and - controlling the switches of the switching matrix (34) in such a way that the DC-DC converter (18, 40) affected by the fault is separated from the battery units (14, 16) and a DC-DC conversion of the DC-DC converter (18, 40) affected by the fault is taken over by the third DC-DC converter (50) if necessary.