Measuring assembly for detecting faults in a controller

Abstract

The invention relates to a measuring assembly (10) for detecting faults in a controller (1) having two galvanically isolated voltage domains (3, 5), each voltage domain having a voltage source (U1, U2) and different nominal voltages. The measuring assembly comprises an ohmic resistor (Rp), which is connected between the two galvanically isolated voltage domains (3, 5) and connects together the reference potentials of the two voltage sources (U1, U2) of the two voltage domains (3, 5), and a measuring device (12), which is designed to determine a current flow through the ohmic resistor (Rp), wherein the measuring device (12) detects a short circuit (7) between the two voltage domains (3, 5) if a short-circuit current (Ik) flowing through the ohmic resistor (Rp) is detected which lies above a specified limit value. The invention also relates to a controller (1) having at least one such measuring assembly (10) for detecting faults.

Description

[0001] R. 418045

[0002] - 1 -

[0003] Description

[0004] title

[0005] A measuring arrangement for fault detection in a control unit

[0006] The invention relates to a measuring arrangement for fault detection in a control unit. The present invention also relates to a control unit with such a measuring arrangement for fault detection.

[0007] Modern vehicles increasingly use different voltage domains. As can be seen in Fig. 1, an illustrated embodiment of a control unit 1A of a vehicle, for example, provides a first voltage domain 3 with a first voltage source 4 and a first nominal voltage U1 of 48 volts for high-current consumers V1, and a second voltage domain 5 with a second voltage source 6 and a second nominal voltage U2 of 12 volts for standard consumers V2, V3. Since the cables of these voltage domains 3, 5 can potentially be short-circuited in the vehicle, the standard consumers V2, V3 of the second voltage domain 5 with the second nominal voltage U2 of 12 volts can be destroyed by a short circuit 7 to the first voltage domain 3 with the first nominal voltage U1 of 48 volts. This is illustrated in Fig. 1 by the dashed outline around the standard consumer V2.Since many standard consumers V2, V3 of the second voltage domain 5 with the second nominal voltage U2 of 12 volts would be destroyed by a short circuit 7 to the first voltage domain 3 with the first nominal voltage U1 of 48 volts, the standard consumers V2, V3 of the second voltage domain 5 are protected accordingly. For units with few supply lines, this can be accomplished with little effort. However, for control units that have a large number of lines to the vehicle, such as an airbag control unit, protecting the individual lines is not possible or only with great difficulty. R. 418045.

[0008] - 2 -

[0009] As can be seen in Fig. 2, the standard loads V2, V3 of the second voltage domain 5 can, for example, be galvanically decoupled from the first voltage domain 3 in order to still protect them. This is preferably achieved by an isolated DC / DC converter (not shown) which isolates the second voltage domain 5, with its second nominal voltage U1 of 12 volts, from the first voltage domain 3, with its first nominal voltage U1 of 48 volts. This measure prevents the standard loads V2, V3 of the second voltage domain 5 from being destroyed by a single short circuit 7 to the first voltage domain 3. However, such a short circuit 7 between the two voltage domains 3, 5 can no longer be detected and thus becomes a "latent fault".If another short circuit 7 occurs between the two voltage domains 3, 5, this can again lead to the destruction of a standard consumer V2, V3 of the second voltage domain 5.

[0010] This procedure can also be used if the standard loads V2 and V3 of the second voltage domain 5 are supplied from the first voltage domain 3. In this case, the DC / DC converter, in addition to galvanic isolation, also reduces the voltage to the permissible value.

[0011] From DE 10235 162 A1, a control unit in a vehicle is known which is characterized by the fact that the power supply runs via a converter that provides galvanic isolation. In addition, the component isolated by this galvanic isolation is connected for data exchange with external components and other components in the control unit that are not galvanically isolated by means of a coupling element that also provides galvanic isolation.

[0012] From DE 102015 211 663 A1, an arrangement for use in a motor vehicle is known, comprising at least one central control unit, at least two decentralized control units, and at least two actuators. In this arrangement, there is at least one signal connection between the central control unit and each decentralized control unit. There is also at least one signal connection between each decentralized control unit and each actuator. (R. 418045)

[0013] - 3 -

[0014] The vehicle has a first electrical system and a second electrical system; the first and second electrical systems are galvanically isolated from each other or connected at a star point. The first electrical system includes at least part of the central control unit. The second electrical system includes at least part of the actuators. The second electrical system includes at least part of the decentralized control units.

[0015] Disclosure of the invention

[0016] The measuring arrangement for fault detection in a control unit with the features of independent claim 1 and the control unit for a vehicle with the features of independent claim 8 each have the advantage that a short circuit between two galvanically isolated voltage domains with different nominal voltages can be reliably detected.

[0017] If a galvanic isolator is used to decouple a second voltage domain with a lower nominal voltage from a first voltage domain with a higher nominal voltage, the reference potential of the second voltage domain on the secondary side of the galvanic isolator is undefined relative to the reference potential of the first voltage domain (floating potential). Therefore, a single short circuit between terminals of the two galvanically isolated voltage domains can no longer be detected. Each individual short circuit between two terminals of the two voltage domains would thus become a "dormant" or "latent" fault. A second short circuit between two other terminals of the two voltage domains could then lead to the destruction of standard loads in the second voltage domain or to the destruction of the control unit.To solve the problem of failing to detect a short circuit between two terminals of the two voltage domains, in embodiments of the invention, the reference potentials of the two voltage domains can be connected to each other via an ohmic resistor. This provides a high-impedance reference potential against which a standard diagnostic tool is able to detect a single short circuit. By a current flowing through the R. 418045.

[0018] - 4 -

[0019] In the event of a short circuit, the corresponding short circuit between the two voltage domains can be detected by measuring the ohmic resistance.

[0020] Embodiments of the present invention provide a measuring arrangement for fault detection in a control unit with two galvanically isolated voltage domains, each comprising a voltage source and different nominal voltages. The measuring arrangement includes an ohmic resistor, which is connected between the two galvanically isolated voltage domains and connects the reference potentials of the two voltage sources of the two voltage domains, and a measuring device configured to detect current flow through the ohmic resistor. The measuring device detects a short circuit between the two voltage sources when a short-circuit current exceeding a predetermined threshold is detected through the ohmic resistor.

[0021] Furthermore, a control unit for a vehicle, with two galvanically isolated voltage domains, each comprising a voltage source and different nominal voltages, and such a measuring arrangement for fault detection is proposed.

[0022] In this context, a control unit can be understood as an electrical device, such as an airbag control unit, which processes or evaluates acquired sensor signals. The control unit can have at least one interface, which can be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the control unit. However, it is also possible that the interfaces are separate integrated circuits or at least partially consist of discrete components. In the case of a software-based interface, the interfaces can be software modules, which, for example, are located on a microcontroller alongside other software modules. A computer program product with program code stored on a machine-readable medium such as semiconductor memory, hard disk storage, or optical memory is also advantageous. 418045

[0023] - 5 -

[0024] The memory is stored and used to perform the evaluation when the program is executed by the control unit.

[0025] The measures and further developments listed in the dependent claims enable advantageous improvements to the measuring arrangement for fault detection in a control unit specified in independent claim 1 and to the control unit for a vehicle specified in independent claim 8.

[0026] A particular advantage is that the measuring device can generate and display an error message if a short circuit between the two voltage sources is detected. This allows the driver to be warned in time and contact or visit a repair shop.

[0027] In a further advantageous embodiment of the measuring arrangement, the ohmic resistor can provide a high-impedance reference potential. The ohmic resistor can preferably have a value in the range of 1 kilohm to 5 kilohm. Furthermore, the ohmic resistor can limit the short-circuit current and thereby prevent damage to any of the connected devices.

[0028] In a further advantageous embodiment of the measuring arrangement, a capacitor can be connected in parallel to the ohmic resistor, which is designed to reduce EMC interference (EMC: Electromagnetic Compatibility).

[0029] In a further advantageous embodiment of the measuring arrangement, the measuring device can be designed as a voltmeter, which detects a voltage increase across the ohmic resistor caused by the short-circuit current. The corresponding short-circuit current can then be determined from the detected voltage increase.

[0030] In an advantageous embodiment of the control unit, a first nominal voltage of a first voltage source of a first voltage domain can be higher than a second nominal voltage of a second voltage source of a second R. 418045

[0031] - 6 -

[0032] This can be a voltage domain. For example, the first nominal voltage could be 48 volts, and the second nominal voltage could be 12 volts.

[0033] In a further advantageous embodiment of the control unit, the two voltage domains can be galvanically isolated from each other by an isolation transformer. The first voltage domain, with the higher nominal voltage, can be connected to a primary side of the isolation transformer, and the second voltage domain, with the lower nominal voltage, can be connected to a secondary side of the isolation transformer.

[0034] An embodiment of the invention is shown in the drawings and is explained in more detail in the following description. In the drawings, identical reference numerals denote components or elements that perform the same or analogous functions.

[0035] Brief description of the drawings

[0036] Fig. 1 shows a schematic representation of a first embodiment of a known control unit with two voltage domains, each comprising a voltage source and different nominal voltages.

[0037] Fig. 2 shows a schematic representation of a second embodiment of a known control unit with two galvanically isolated voltage domains, each comprising a voltage source and different nominal voltages.

[0038] Fig. 3 shows a schematic representation of an embodiment of a control unit according to the invention with two galvanically isolated voltage domains, each comprising a voltage source and different nominal voltages, and an embodiment of a measuring arrangement according to the invention for fault detection in a control unit.

[0039] Embodiments of the invention R. 418045

[0040] - 7 -

[0041] As can be seen from Fig. 3, the illustrated embodiment of a control unit 1 C according to the invention for a vehicle comprises two galvanically isolated voltage domains 3, 5, each comprising a voltage source 4, 6 and different nominal voltages U1, U2, and a measuring arrangement 10 according to the invention for fault detection.

[0042] As can be further seen from Fig. 3, the illustrated embodiment of the measuring arrangement 10 according to the invention for fault detection in a control unit 1 C comprises an ohmic resistor Rp, which is connected between the two galvanically isolated voltage domains 3, 5 and connects the reference potentials of the two voltage sources 4, 6 of the two galvanically isolated voltage domains 3, 5, and a measuring device 12, which is designed to detect a current flow through the ohmic resistor Rp. The measuring device 12 detects a short circuit 7 between the two voltage domains 3, 5 when a short-circuit current Ik exceeding a predetermined threshold value is detected through the ohmic resistor Rp.

[0043] In the illustrated embodiment of the control unit 1 C, a first voltage source 4 of a first voltage domain 3 has a first nominal voltage U1 of 48 volts, which is higher than a second nominal voltage U2 of 12 volts of a second voltage source 6 of a second voltage domain 5. Furthermore, the two voltage domains 3 and 5 are galvanically isolated from each other by an isolation transformer (not shown in detail).

[0044] In the illustrated embodiment of the measuring arrangement 12, the measuring device 12 generates and outputs an error message when a short circuit 7 between the two voltage domains 3, 5 is detected.

[0045] In the illustrated embodiment of the measuring arrangement 12, the ohmic resistor Rp provides a high-impedance reference potential. For this purpose, the ohmic resistor Rp has a value in the range of 1 kilohm to 5 kilohm. Furthermore, the ohmic resistor Rp limits the short-circuit current Ik.R. 418045

[0046] - 8 -

[0047] As can be seen from Fig. 3, a capacitor Cp is connected in parallel to the ohmic resistor Rp and designed to reduce EMC interference.

[0048] As can be seen in Fig. 3, the measuring device 12 in the illustrated embodiment is designed as a voltage measuring device V, which detects a voltage increase across the ohmic resistor Rp caused by the short-circuit current Ik. Based on the voltage increase and the value of the ohmic resistor Rp, the short-circuit current Ik flowing through the ohmic resistor can then be determined.

Claims

R. 418045 - 9 - Claims 1. Measuring arrangement (10) for fault detection in a control unit (1 C) with two galvanically isolated voltage domains (3, 5), each comprising a voltage source (4, 6) and different nominal voltages (U1, U2), comprising an ohmic resistor (Rp) which is connected between the two galvanically isolated voltage domains (3, 5) and connects the reference potentials of the two voltage sources (4, 6) of the two voltage domains (3, 5) to each other, and a measuring device (12) which is configured to detect a current flow through the ohmic resistor (Rp), wherein the measuring device (12) detects a short circuit (7) between the two voltage domains (3, 5) when a short-circuit current (Ik) through the ohmic resistor (Rp) exceeding a predetermined threshold value is detected.

2. Measuring arrangement (12) according to claim 1 , characterized in that the measuring device (12) generates and outputs an error message when a short circuit (7) between the two voltage domains (3, 5) is detected.

3. Measuring arrangement (12) according to claim 1 or 2, characterized in that the ohmic resistance (Rp) provides a high-impedance reference potential.

4. Measuring arrangement (12) according to one of claims 1 to 3, characterized in that the ohmic resistance (Rp) has a value in the range of 1 kiloohm to 5 kiloohm.

5. Measuring arrangement (12) according to one of claims 1 to 4, characterized in that the ohmic resistance (Rp) limits the resulting short-circuit current (Ik). R. 418045 - 10 - 6. Measuring arrangement (12) according to one of claims 1 to 5, characterized in that a capacitor (Cp) is connected in parallel to the ohmic resistor (Rp), which is designed to reduce EMC interference.

7. Measuring arrangement (12) according to one of claims 1 to 6, characterized in that the measuring device (12) is designed as a voltage measuring device (V) which detects a voltage increase at the ohmic resistance (Rp) caused by the short-circuit current (Ik).

8. Control unit (1 C) for a vehicle, comprising two galvanically isolated voltage domains (3, 5), each comprising a voltage source (4, 6) and different nominal voltages (U1, U2), and a measuring arrangement (10) for fault detection, which is designed according to one of claims 1 to 7.

9. Control unit (1) according to claim 8, characterized in that a first nominal voltage (U1) of a first voltage source (4) of a first voltage domain (3) is higher than a second nominal voltage (U2) of a second voltage source (6) of a second voltage domain (5).

10. Control unit (1) according to claim 8 or 9, characterized in that the two voltage domains (3, 5) are galvanically isolated from each other by a transformer.

Images