Redundant electrical ground supply system

Abstract

A redundant electrical ground supply system is provided. The invention relates to a redundant electrical ground supply system (1) comprising: a common electrical ground output (2) configured to be electrically connected or disconnected with a first electrical ground input (3a) and / or a second electrical ground input (3b); a first resistor (4a) configured to be electrically connected to or disconnected from the first electrical ground input (3a) and / or a battery voltage (VBAT); and a second resistor (4b) configured to be electrically connected to or disconnected from the second electrical ground input (3b) and / or the battery voltage (VBAT).

Description

Technical Field

[0001] The present invention relates to a redundant electrical ground supply system and a method for diagnosing a redundant electrical ground supply system. Background Art

[0002] Redundant power supplies are used in a variety of applications, from critical computer systems to vehicles. The basis of redundant power supplies is two or more power sources connected in parallel. Even in the event of a failure of one of the power sources, the other power sources are still able to supply power to the load connected to the redundant power supply. In this way, redundancy improves robustness, fail-safety, and availability.

[0003] In addition to redundant power supplies, it is also desirable to provide redundant ground connections for critical systems. The ground connection of an electrical system is as important as its connection to the power source, such as the (positive) battery voltage. Failure of the ground connection or high contact resistance due to corrosion or loose clamping connections, for example, can lead to power failure in critical systems. Therefore, the ground connections of critical systems are often also redundant, i.e. the system is connected to multiple ground rails.

[0004] However, there is still a need for a method to monitor the status of a redundant ground connection and be able to detect a possible fault in one of its sub-connections in order to initiate corresponding measures. At the same time, such additional safety measures should be implemented with minimal additional components to reduce complexity and cost. Summary of the invention

[0005] In a first aspect, the present invention relates to a redundant electrical grounding supply system, which includes: a common electrical grounding output terminal, which is configured to be electrically connected or disconnected with a first electrical grounding input terminal and / or a second electrical grounding input terminal; a first resistor, which is configured to be electrically connected or disconnected with the first electrical grounding input terminal and / or a battery voltage; and a second resistor, which is configured to be electrically connected or disconnected with the second electrical grounding input terminal and / or a battery voltage.

[0006] The first electrical ground input terminal can be connected to the first ground rail, and the second electrical ground input terminal can be connected to the second ground rail. Therefore, the two ground rails can provide a ground potential to the electrical ground supply system. A redundant ground potential is provided at the common electrical ground output terminal of the system according to the present invention. In the case of normal operation of the system and the ground supply rail, the common electrical ground output terminal is in electrical contact with at least two ground potentials with a low contact resistance and provides a redundant ground potential, for example, to provide a redundant ground potential to a critical system. It should be noted that the system according to the present invention may include more than two ground input terminals.

[0007] Since both electrical ground inputs can be connected or disconnected individually to the common ground output, and since both resistors can be connected or disconnected individually to the common ground output and / or the battery voltage, it is possible to diagnose whether the ground connection of the two ground inputs is missing or the value of their contact resistance. Furthermore, the state of the diodes and switching elements of the system can be diagnosed, for example, whether they are stuck open or closed. In this way, the system according to the invention provides a redundant electrical ground supply, wherein the system can be diagnosed with respect to the ground inputs of the system and its internal components.

[0008] The redundant electrical ground supply system according to the invention may further comprise a first switching element, which is configured to electrically connect or disconnect the common ground output terminal with the first electrical ground input terminal; and a second switching element, which is configured to electrically connect or disconnect the common ground output terminal with the second electrical ground input terminal. The switching element allows the common ground output terminal to be connected or disconnected from the ground input terminal. This allows diagnosing the state of the ground connection and detecting, for example, whether the ground connection of one of the ground input terminals is lost. Such a loss of ground connection may be due to a mechanical connection failure, a cable tear, a broken solder joint, etc. It should be noted that in the case of more than two ground input terminals, the system according to the invention may comprise more than the first switching element and the second switching element.

[0009] The redundant electrical ground supply system according to the present invention may also include a third switching element, which is configured to electrically connect or disconnect the first resistor with the first electrical ground input or the battery voltage; and a fourth switching element, which is configured to electrically connect or disconnect the second resistor with the second electrical ground input or the battery voltage. The third switching element and the fourth switching element allow the resistor to be connected or disconnected with its corresponding ground input. In this way, additional diagnostic information can be obtained by measuring the potential at the resistor in a defined state (open or closed) of the switching element. For example, the contact resistance of the ground connection and the diagnostic switch element itself can be diagnosed. It should be noted that in the case of more than two ground inputs, the system according to the present invention may include more switching elements to connect or disconnect the common ground output with the corresponding ground input.

[0010] The redundant electrical ground supply system according to the present invention may also include a third resistor, which is connected in series with the first resistor and the third switching element to form a voltage divider with the first resistor; and a fourth resistor, which is connected in series with the second resistor and the fourth switching element to form a voltage divider with the second resistor. Using a voltage divider instead of a single resistor allows additional diagnostic information to be obtained. For example, if the potential at the intermediate junction of the voltage divider is higher than the expected potential by a predetermined threshold, it can be inferred that the ground contact resistance of the corresponding ground input terminal is too high. On the contrary, if the potential at the intermediate junction of the voltage divider is close to 0V, it can be inferred that the switch in series with the voltage divider is stuck open.

[0011] The redundant ground supply system according to the present invention may also include a control unit, which is configured to control the states of the first switching element, the second switching element, the third switching element and the fourth switching element. Such a control unit may be, for example, a safety microcontroller unit with a specific safety qualification such as according to an automotive safety integrity level (ASIL) risk classification scheme. The control unit allows the system according to the present invention to be automatically diagnosed by correspondingly connecting and disconnecting the ground input and the resistor and measuring the battery voltage and the potential at the resistor of the system to obtain diagnostic information. The diagnostic method can be implemented in the control unit by means of software.

[0012] The control unit may also be configured to measure the potential of the battery voltage at one end of the first resistor and at one end of the second resistor. In this way, the control unit obtains diagnostic information about the quality of the ground connection and about switches and diodes employed in the system.

[0013] The control unit may be configured to output a signal and / or change the contents of a portion of a non-volatile memory in response to measuring a potential that deviates from an expected potential by a predetermined threshold after setting the states of the first switching element D1, the second switching element D2, the third switching element T1, and the fourth switching element T2 to a predetermined configuration. This allows a possible fault to be indicated to a user, a driver, and / or another system. For example, in the case where the system of the present invention is used in a vehicle, if the diagnosis is performed when the engine is turned off, the signal may prevent the vehicle from being started. Writing the diagnostic results to a non-volatile memory may facilitate error diagnosis and maintenance. For example, a detected fault in one of the ground connections may be recorded to a fault memory that may be read during maintenance so that the faulty ground connection may be repaired.

[0014] The redundant ground supply system according to the invention may further comprise a limp home logic comprising at least one control input and being configured to provide a defined potential to the inputs of the first, second, third and fourth switching elements in the absence of a defined potential at at least one control input thereof. The limp home logic provides a defined state to the switching elements of the system during startup and in the event of a fault. This ensures that the system provides a proper ground connection as far as possible in all cases.

[0015] The at least one control input of the limp home logic may be electrically connected to at least one control output of the control unit. In this way, the control unit can control the state of the switching element and perform diagnostics of the system, but in case of start-up or control unit failure, the limp home logic ensures a defined state of the switching element and a correct connection of the common ground output to the ground input.

[0016] Another aspect of the invention relates to a method of diagnosing an electrical ground supply system according to the invention and as described herein. The method comprises the steps of disconnecting the common electrical ground output from the first electrical ground input; connecting the common electrical ground output to the second electrical ground input; disconnecting the first resistor from the first electrical ground input and / or from the battery voltage; disconnecting the second resistor from the second electrical ground input and / or from the battery voltage; and measuring the potential between the battery voltage and the common ground output, and / or measuring the potential at the first resistor.

[0017] The method allows diagnosing whether a first switching element connecting or disconnecting the common ground output to the first ground input is stuck, whether the ground connection of the second ground input is lost, or whether a third switching element connected to the first resistor is stuck conducting.

[0018] The method may further comprise the steps of: disconnecting the common electrical ground output from the first electrical ground input and the second electrical ground input; disconnecting the first resistor from the first electrical ground input and / or from the battery voltage; disconnecting the second resistor from the second electrical ground input and / or from the battery voltage; and measuring the potential between the battery voltage and the common ground output. This allows diagnosing whether one of the first switching element or the second switching element is stuck closed.

[0019] The method may further comprise the steps of: connecting the common electrical ground output to the first electrical ground input; disconnecting the common electrical ground output from the second electrical ground input; connecting the first resistor to the first electrical ground input and the battery voltage; connecting the second resistor to the second electrical ground input and the battery voltage; and measuring the potential at the first resistor. This allows diagnosing whether the third switching element connected to the first resistor is stuck open or whether the contact resistance of the first ground input is too high.

[0020] The method may further comprise the steps of: connecting the common electrical ground output to the first electrical ground input; disconnecting the common electrical ground output from the second electrical ground input; disconnecting the first resistor from the first electrical ground input and / or from the battery voltage; disconnecting the second resistor from the second electrical ground input and / or from the battery voltage; and measuring the potential between the battery voltage and the common ground output and / or measuring the potential at the first resistor. This allows diagnosing whether the second switching element connecting or disconnecting the common ground output from the second ground input is stuck, whether the ground connection of the first ground input is lost, or whether the fourth switching element connected to the second resistor is stuck in conduction.

[0021] The method may further comprise the steps of: disconnecting the common electrical ground output from the first electrical ground input; connecting the common electrical ground output to the second electrical ground input; connecting the first resistor to the first electrical ground input and the battery voltage; connecting the second resistor to the second electrical ground input and the battery voltage; and measuring the potential at the second resistor. This allows diagnosing whether the fourth switching element connected to the second resistor is stuck open or whether the contact resistance of the second ground input is too high.

[0022] The invention also relates to a computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the following detailed description a possible embodiment of the invention is described in more detail with reference to the following figure:

[0024] Figure 1 Exemplary embodiments of the present invention are illustrated. DETAILED DESCRIPTION

[0025] For the sake of brevity, only a few embodiments will be described below. Those skilled in the art will recognize that the features described with reference to these specific embodiments can be modified and combined in different ways, and individual features can also be omitted. The general explanations in the above sections also apply to the more detailed explanations below.

[0026] Figure 1 An exemplary embodiment of the present invention is illustrated by a redundant ground supply system 1. The system 1 comprises a common electrical ground output 2. The ground output 2 provides a redundant ground potential, for example, to critical systems such as a system on a chip (SoC), a microcontroller unit (MCU), an Ethernet switch, etc. Such critical systems can be used, for example, in a vehicle and can control critical functions such as adaptive cruise control, lane assistance, brake assistance and autonomous driving functions. The common ground output 2 also provides a ground potential for elements of the system 1 itself (e.g. a control unit X), which will be described in more detail below.

[0027] The common ground output terminal 1 is configured to be electrically connected or disconnected with the first electrical ground input terminal 3a and / or the second electrical ground input terminal 3b through corresponding switching elements 6a and 6b, which will be described in more detail below. The ground input terminals 3a and 3b are configured to be connected to corresponding ground rails, ground terminals, ground clamps, etc. In order to provide redundancy, the input terminals 3a and 3b should be connected to different ground sources, such as ground rails.

[0028] System 1 also includes a first resistor 4a configured to be electrically connected or disconnected with a battery voltage VBAT and a second resistor configured to be electrically connected or disconnected with the battery voltage VBAT. Instead of the battery voltage VBAT, the first resistor or the second resistor may alternatively be configured to be connected or disconnected with the first electrical ground input terminal 3a or the second electrical ground input terminal 3b, respectively. The battery voltage VBAT can be supplied by a redundant power supply, which includes, for example, two independent power supply branches and achieves high availability for safety-critical applications. The connection or disconnection of the first resistor 4a is completed by the third switching element 7a, and the connection or disconnection of the second resistor 4b is completed by the fourth switching element 7b. Switching elements 7a and 7b will be described in more detail below.

[0029] exist Figure 1 In the embodiment of the redundant ground supply system 1, the redundant ground supply system 1 further comprises a third resistor 5a connected in series with the first resistor 4a and the third switching element 7a to form a voltage divider with the first resistor 4a. In addition, the system comprises a fourth resistor 5b connected in series with the second resistor 4b and the fourth switching element 7b to form a voltage divider with the second resistor 4b.

[0030] The switching elements 6a, 6b, 7a, 7b can be implemented by field effect transistors FET, such as MOSFETs. In addition, the switching elements 6a and 6b can be implemented as "ideal diodes" that have lower voltage drops and leakage currents than conventional MOSFETs. In addition, the ideal diode advantageously avoids compensating the current between the ground input terminals 3a and 3b in the case where one of the ground input terminals 3a and 3b includes a poor ground connection or has even lost ground contact due to, for example, high contact resistance. Each of the switching elements 6a, 6b, 7a and 7b includes an input that allows the state of the switching element to be controlled, i.e., conductive (on / closed) or non-conductive (off / open).

[0031] according to Figure 1 The redundant electrical ground supply system 1 of the embodiment further comprises a control unit 8, which is configured to control the states of the first switch element 6a, the second switch element 6b, the third switch element 7a and the fourth switch element 7b, respectively. The control unit may be, for example, a safety microcontroller unit having a specific safety qualification, such as according to the Automotive Safety Integrity Level (ASIL) risk classification scheme. The control unit may also be implemented as an ASIC, a conventional microprocessor, etc.

[0032] In order to control the state of the switching elements 6a, 6b, 7a and 7b, the control unit includes a plurality of output terminals 9, which can operate at a transistor-transistor logic (TTL) voltage level or a complementary metal oxide semiconductor (CMOS) voltage level. The control unit 8 also includes an input terminal 10, which is configured to measure the potential between the battery voltage VBAT and the ground 2, the potential U (R1) at the intermediate junction of the first voltage divider formed by resistors 4a and 5a, and the potential U (R2) at the intermediate junction of the second voltage divider formed by resistors 4b and 5b. To this end, the control unit may include an analog-to-digital converter (ADC). Alternatively, the ADC may be one or more separate components, and the measured potential may be output to the control unit 8 in a digital format. In addition, an amplifier (such as a differential amplifier) ​​may be provided between the measurement point and the ADC or the control unit 8 to amplify the voltage to be measured and / or provide impedance matching.

[0033] The control unit 8 may be configured to output a signal ( Figure 1 ) and / or changing the non-volatile memory ( Figure 1 The non-volatile memory may be an EEPROM or similar device and may be internal or external to the control unit 8. The signal may be provided to another control unit and / or a visual and / or optical warning device.

[0034] according to Figure 1 The redundant electrical ground supply system 1 of the embodiment also includes a limp home logic 11, which includes a plurality of control inputs 12 connected to the corresponding outputs 9 of the control unit 8. The limp home logic 11 includes corresponding outputs 13, which are connected to the inputs of the first switching element 6a, the second switching element 6b, the third switching element 7a and the fourth switching element 7b. Therefore, the limp home logic 11 defines the state (on / off) of the switching elements. The limp home logic 11 provides a defined potential to the inputs of the first switching element 6a, the second switching element 6b, the third switching element 7a and the fourth switching element 7b, while there is no defined potential at its input 12. To this end, the limp home logic 11 can use a pull-up or pull-down resistor, which pulls its output 13 to a defined potential. In normal operation, the state of the output 13 of the limp home logic corresponds to the state of the output 9 of the control unit 8. Thus, the control unit 8 is able to control the state (on / off) of the switching elements 6a, 6b, 7a, 7b. During startup or resetting of the control unit 8, its output terminal 9 is advantageously in a neutral state (e.g., open, high resistance or "tri-state") so that the limp-home logic 11 can pull the control input terminals of the switching elements 6a, 6b, 7a and 7b to a defined potential and the common ground output terminal 2 is electrically connected to both ground input terminals 3a and 3b.

[0035] In the following, it is described how the control unit 8 diagnoses the following by setting its output 9 and measuring the potential at its input 10. Figure 1 The following example assumes that the system 1 according to the invention is used in an automobile, but the invention is not limited to application in automobiles. Furthermore, it is assumed that the voltage divider comprises resistors of equal value, so that the potential at the intermediate junction is half the voltage at the voltage divider input. The invention is not limited to such a resistor ratio.

[0036] about Figure 1 The following table shows how to diagnose the first ground input terminal 3a and the second ground input terminal 3b and the switching elements 6a, 6b and 7a using the method according to the present invention:

[0037]

[0038]

[0039] about Figure 1 The following table shows how to diagnose the first ground input terminal 3a and the second ground input terminal 3b and the switching elements 6a, 6b and 7b using the method according to the present invention:

[0040]

[0041]

[0042] As shown in the two tables, the quality of the ground connection of the two ground inputs 3a and 3b and the correct functioning of the switching elements can be diagnosed with the method according to the invention by setting the state of the switching elements accordingly and measuring the response of the potentials at the three test points VBAT, U(R1) and U(R2). If the measured potentials do not match the expected values, a fault condition is detected. The self-test described can be performed in non-critical or safe states, for example in the case of a vehicle, when the vehicle is parked and the ignition is off.

[0043] The self-test described above may be performed by the control unit 8 described herein, which may be a microcontroller, an ASIC or a similar device. To this end, the method of diagnosing the redundant electrical ground supply system 1 as disclosed herein may be implemented in hardware or software, or may be implemented partially in hardware and partially in software. Hardware suitable for implementing the method and apparatus according to the present invention includes a central processing unit (CPU), a microcontroller, an application specific integrated circuit (ASIC), etc. (All or part of) the software implementation may include compiling source code to obtain machine-readable instructions, which, when executed, cause a computer, a CPU, a microcontroller, etc. to perform all or part of the method steps described herein.

Claims

1. A redundant electrical grounding supply system (1), the redundant electrical grounding supply system comprising: A common electrical ground output terminal (2) configured to be electrically connected to or disconnected from the first electrical ground input terminal (3a) and / or the second electrical ground input terminal (3b); a first resistor (4a) configured to be electrically connected to or disconnected from the first electrical ground input terminal (3a) and / or a battery voltage (VBAT); and A second resistor (4b) is configured to be electrically connected to or disconnected from the second electrical ground input terminal (3b) and / or a battery voltage (VBAT).

2. The redundant electrical grounding supply system (1) according to claim 1, further comprising: a first switching element (6a) configured to electrically connect or disconnect the common ground output terminal (2) from the first electrical ground input terminal (3a); and A second switch element (6b) is configured to electrically connect or disconnect the common ground output terminal (2) and the second electrical ground input terminal (3b).

3. The redundant electrical grounding supply system (1) according to claim 1 or 2, further comprising: a third switching element (7a) configured to electrically connect or disconnect the first resistor (4a) from the first electrical ground input terminal (3a) or the battery voltage (VBAT); and A fourth switch element (7b) is configured to electrically connect or disconnect the second resistor (4b) from the second electrical ground input terminal (3b) or the battery voltage (VBAT).

4. The redundant electrical grounding supply system (1) according to claim 3, further comprising: a third resistor (5a) connected in series with the first resistor (4a) and the third switching element (7a) to form a voltage divider with the first resistor (4a); and A fourth resistor (5b) is connected in series with the second resistor (4b) and the fourth switching element (7b) to form a voltage divider with the second resistor (4b).

5. A redundant electrical ground supply system (1) according to claim 3 or 4 when dependent on claim 2, further comprising: A control unit (8) is configured to control the states of the first switching element (6a), the second switching element (6b), the third switching element (7a) and the fourth switching element (7b).

6. The redundant ground supply system (1) according to claim 5, wherein: The control unit (8) is further configured to measure the potential of the battery voltage (VBAT) at one end of the first resistor (4a) and at one end of the second resistor (4b).

7. The redundant ground supply system (1) according to claim 6, wherein: The control unit (8) is configured to output a signal and / or change the contents of a portion of a non-volatile memory in response to measuring a potential that deviates from an expected potential by a predetermined threshold after setting the states of the first switching element (6a), the second switching element (6b), the third switching element (7a) and the fourth switching element (7b) to a predetermined configuration.

8. A redundant electrical ground supply system (1) according to any one of claims 3 to 7 when dependent on claim 2, further comprising: A limp-home logic (11) comprising at least one control input (12) and configured to provide a defined potential to inputs of the first switching element (6a), the second switching element (6b), the third switching element (7a) and the fourth switching element (7b) in the absence of a defined potential at the at least one control input (12) thereof.

9. A redundant electrical ground supply system (1) according to claim 8 when dependent on one of claims 5 to 7, wherein: The at least one control input (12) of the limp-home logic (8) is electrically connected to at least one control output (9) of the control unit (8).

10. A method of diagnosing an electrical ground supply system (1) according to any one of claims 1 to 9, the method comprising the following steps: Disconnecting the common electrical ground output terminal (2) from the first electrical ground input terminal (3a); connecting the common electrical ground output terminal (2) to the second electrical ground input terminal (3b); Disconnecting the first resistor (4a) from the first electrical ground input (3a) and / or from the battery voltage (VBAT); disconnecting the second resistor (4b) from the second electrical ground input (3b) and / or from the battery voltage (VBAT); and The potential between the battery voltage (VBAT) and the common ground output terminal (2) is measured, and / or the potential at the first resistor (4a) is measured.

11. The method according to claim 10, further comprising the steps of: Disconnecting the common electrical ground output terminal (2) from the first electrical ground input terminal (3a) and the second electrical ground input terminal (3b); Disconnecting the first resistor (4a) from the first electrical ground input (3a) and / or from the battery voltage (VBAT); disconnecting the second resistor (4b) from the second electrical ground input (3b) and / or from the battery voltage (VBAT); and The potential between the battery voltage (VBAT) and the common ground output terminal (2) is measured.

12. The method according to claim 10 or 11, further comprising the following steps: connecting the common electrical ground output terminal (2) to the first electrical ground input terminal (3a); Disconnecting the common electrical ground output terminal (2) from the second electrical ground input terminal (3b); connecting the first resistor (4a) to the first electrical ground input (3a) and the battery voltage (VBAT); connecting the second resistor (4b) to the second electrical ground input (3b) and the battery voltage (VBAT); and The potential at the first resistor (4a) is measured.

13. The method according to any one of claims 10 to 12, further comprising the steps of: Connecting the common electrical ground output terminal (1) to the first electrical ground input terminal (3a); Disconnecting the common electrical ground output terminal (1) from the second electrical ground input terminal (3b); Disconnecting the first resistor (4a) from the first electrical ground input (3a) and / or from the battery voltage (VBAT); disconnecting the second resistor (4b) from the second electrical ground input (3b) and / or from the battery voltage (VBAT); and The potential between the battery voltage (VBAT) and the common ground output terminal (1) and / or the potential at the first resistor (4a) is measured.

14. The method according to any one of claims 10 to 13, further comprising the steps of: Disconnecting the common electrical ground output terminal (2) from the first electrical ground input terminal (3a); connecting the common electrical ground output terminal (2) to the second electrical ground input terminal (3b); connecting the first resistor (4a) to the first electrical ground input (3a) and the battery voltage (VBAT); connecting the second resistor (R2b) to the second electrical ground input (3b) and the battery voltage (VBAT); and The potential at the second resistor (4b) is measured.

15. A computer program product comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 10 to 14.

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