Electrical arrangement with a redundant electrical transmission path and means for detecting a fault state of the same, as well as a method for detecting a fault state of the redundant electrical transmission path of the electrical arrangement.

Description

[0001] The invention relates to an electrical arrangement with a redundant electrical transmission path and means for detecting a defect in the redundant electrical transmission path, as well as methods for detecting a defect in the redundant electrical transmission path.

[0002] Such an arrangement is known, for example, from DE 10 2019 217 083 A1.

[0003] For safety-critical components, it must be ensured that their power supplies are not interrupted by broken wires, faulty connectors, or corrosion. This also applies to safety-critical functions that are triggered, for example, by an electrical signal. An example of this is the power supply for airbags in vehicles or their deployment by means of an electrical signal supplied via a control line.

[0004] It is known to implement redundant electrical connections in such cases using two parallel electrical lines and to monitor this redundant electrical transmission path in such a way that the failure of one of the two electrical lines is detected.

[0005] From EP 0 953 154 A1, a device and a method for detecting conductor track breaks in solar modules are known. In solar modules constructed from individual solar cells connected via conductor tracks, breaks in the conductor tracks can occur, rendering the solar module unusable. To detect such a conductor track break, it is proposed to couple an inductor to a conductor loop formed between two adjacent solar cells of the solar module. The inductor, together with a capacitor, forms a resonant circuit, which is excited by an AC voltage generator. The change in the oscillator characteristics of the resonant circuit, which depends on the impedance of the conductor loop, is detected by means of a transducer coupled to the resonant circuit.This allows the changes in parameters of the resonant circuit caused by a break in the conductor track to be displayed by means of the transducer.

[0006] Further electrical arrangements for fault detection are described in DE 32 21 176 A1 and DE 10 2013 203 921 A1.

[0007] The object of the invention is to provide an electrical arrangement with a redundant electrical transmission path and simple means for detecting a defect or fault condition of the redundant electrical transmission path. Furthermore, the invention aims to provide a method for detecting a defect or fault condition of the redundant electrical transmission path of the arrangement.

[0008] The first problem is solved by an electrical arrangement having the features of claim 1.

[0009] An electrical arrangement is proposed comprising a first electrical device, a second electrical device, a redundant electrical transmission path with two parallel electrical connecting lines between the first and second electrical devices, and means for detecting a fault condition of the redundant electrical transmission path. The means include a magnetic core with a primary conductor having at least one half-winding loop up to three winding loops, formed by only one of the two connecting lines, and a secondary winding with a greater number of turns than the number of winding loops of the primary conductor. The primary conductor and the secondary winding are strongly inductively coupled via the magnetic core.Furthermore, the means comprise a diagnostic device for evaluating an inductance-dependent measurement signal of the secondary winding, wherein the diagnostic device is configured to compare the inductance-dependent measurement signals (LM) of the secondary winding with a fault threshold usable to distinguish between a fault state and a non-fault state of the redundant electrical transmission path.

[0010] This electrical arrangement thus requires very few and simple means for the inductive detection of a fault condition, such as a failure of one of the two electrical connecting lines of the redundant electrical transmission path caused by a line break. A magnetic core with a primary conductor, formed by one of the two connecting lines, is used as the detection method. A secondary winding of the magnetic core is inductively coupled to the primary conductor, which has only a few winding loops and, in the simplest case, is a straight section of the connecting line, i.e., only half a winding loop.

[0011] These means utilize the principle of impedance transformation, whereby the primary conductor can preferably be implemented with very low resistance, and consequently the transformer formed by the magnetic core together with the primary conductor and the secondary winding does not have any adverse effects on the electrical transmission path for the function of the electrical arrangements.

[0012] Another advantage is that, in order to detect a fault condition, i.e. a defect in the redundant electrical transmission path, the two connecting lines do not necessarily need to be energized.

[0013] The generation of the inductance-dependent measurement signal can be implemented in various ways, which are known to those skilled in the art.

[0014] It is particularly advantageous if the primary conductor has few winding loops, so that the path via the primary conductor and the secondary winding is affected as little as possible even in the event of a fault, i.e. when the fault condition is present.

[0015] The number of turns in the secondary winding is greater than the number of winding loops in the primary conductor. This higher number of turns in the secondary winding reduces the influence of the inductance-dependent measurement signal on both the primary and secondary windings, resulting in a measurement signal with a good signal-to-noise ratio at the secondary winding, which is easy to measure.

[0016] The electrical connecting lines of the redundant electrical transmission path are configured as power supply lines or as signal lines. The electrical connecting lines can also be configured as switching contacts or as plug-in or loop contacts. The latter is achieved by a method with the features of claim 6.

[0017] This method for detecting a fault condition of a redundant electrical transmission path with two parallel electrical connecting lines between a first electrical device and a second electrical device, as well as a measuring inductance which is inductively coupled to at least one half winding loop formed by one of the two connecting lines, comprises, according to the first-mentioned solution, the following method steps: Generating an inductance-dependent measurement signal of the measuring inductance, evaluating the inductance-dependent measurement signal to distinguish a fault state from a non-fault state of the redundant electrical transmission path by comparing the inductance-dependent measurement signal of the measuring inductance with a reference value, in particular a fault threshold, which can be used to distinguish between a fault state and a non-fault state of the redundant electrical transmission path, indicating that a non-fault state exists when the inductance-dependent measurement signal is smaller than the reference value, and indicating that a fault state exists in one of the connecting lines (L1, L2) when the inductance-dependent measurement signal (LM) is larger than the reference value, i.e., in particular the fault threshold.

[0018] Although in most applications it suffices to define an error threshold as a reference value—that is, to define a predetermined constant value above which an error is detected—the present invention also allows the degree of temporal change of the measurement signal to be used as a measure for error detection instead of a fixed threshold. If the signal changes too quickly from one measurement to the next, this can also indicate an error, which can be detected according to the invention. This advantageously allows for the detection of a gradual deterioration of the redundant transmission path. In this way, a type of condition monitoring of the redundant transmission path can be performed.

[0019] The method according to the invention is easily implemented with minimal resources. First, an inductance-dependent measurement signal is generated from a measuring inductor, wherein this measuring inductor is a secondary winding inductively coupled to at least one winding loop formed by one of the two connecting lines as a primary conductor by means of a magnetic core. The inductance-dependent measurement signal of the measuring inductor is evaluated to determine whether or not a fault condition exists in the redundant electrical transmission path. For this purpose, the reference value, in particular the fault threshold, is adapted to the method of generating the inductance-dependent measurement signal so that it is suitable for detecting a defect, e.g., a line break, as a fault condition in the electrical transmission path by comparison with the inductance-dependent measurement signal.

[0020] The generation of the inductance-dependent measurement signal can be implemented in various ways, which are known to those skilled in the art.

[0021] For example, an alternating voltage can be applied to the secondary winding, and the reactance of the resulting alternating current, which is an inductance-dependent measurement signal, can be determined as a reference value for comparison with the fault threshold. The reference value, or fault threshold, is determined such that in a non-fault state, the reference value is lower than this fault threshold, and in a fault state, such as a break in one of the two lines of the redundant transmission path, the reference value is higher than this fault threshold.

[0022] A low reactance indicates that both lines are functioning correctly, meaning there is redundancy in the electrical transmission path. Conversely, a high reactance indicates a failure, i.e., a break in one of the two connecting lines, meaning there is no redundancy in the electrical transmission path in this case.

[0023] Another advanced training method for generating the inductance-dependent measurement signal involves determining the attenuation behavior of a low-pass or high-pass filter built with the secondary winding, for example, an RL or LC filter device. From the inductance-dependent measurement signal indicating the attenuation behavior, an attenuation value is determined as a reference value and compared with a suitably appropriate error threshold.

[0024] According to a further embodiment of the invention, it is possible to build an LC resonant circuit with the secondary winding, so that its resonant behavior is displayed with the inductance-dependent measurement signal and the resonant frequency is determined from this as a reference value in order to be compared with a suitably appropriate error threshold.

[0025] Finally, further training can also be used to detect and evaluate signal distortions of a control signal with multiple frequency components applied to the secondary winding using the inductance-dependent measurement signal. In particular, the time course during the switching on and / or off of the secondary winding can be recorded and evaluated with regard to transient processes and / or decay processes.

[0026] The invention is described in detail below with reference to exemplary embodiments and the accompanying figures. These show: Figure 1: a circuit diagram of an electrical arrangement according to the invention, Figure 2: a schematic detail view of the magnetic core MK according to Figure 1 , and Figure 3 shows a circuit diagram of a further electrical arrangement according to the invention.

[0027] Although the following figures and the accompanying description always refer to an error threshold, as explained in the introduction, the degree of temporal change of the measurement signal can also be used for error detection instead of an error threshold, for example to detect gradual changes in the redundant transmission path.

[0028] The electrical arrangement 1 according to Figure 1The system comprises a first electrical device 2 and a second electrical device 3, which are electrically connected to each other by means of a redundant electrical transmission path 4. This electrical transmission path 4 consists of two electrical connecting lines L1 and L2, which are connected in parallel via nodes K1 and K2.

[0029] The first electrical device 2 is electrically connected to junction K1, such that junction K1 lies outside the first electrical device 2. It is also possible that junction K1 lies inside the first electrical device 2 (dashed representation of the first electrical device 2).

[0030] The second electrical device 3 is electrically connected to junction K2, such that junction K2 lies outside the second electrical device 3. It is also possible that junction K2 lies inside the second electrical device 3 (dashed representation of the second electrical device 3).

[0031] For example, the first electrical device 2 is an airbag control unit and the second electrical device 3 is an airbag module, which is supplied with electrical energy or with a current signal as a trigger signal via the two connecting lines L1 and L2 of the redundant electrical transmission path 4. In the first case, the two connecting lines L1 and L2 represent power supply lines and in the second case, signal lines.

[0032] The electrical arrangement 1 includes means by which a defect, e.g., a break in one of the two connecting lines L1 or L2, is detected. These means detect a fault condition, i.e., a defect, or a non-fault condition of the electrical transmission path 4.

[0033] These devices comprise a magnetic core MK, which has a primary conductor P with at least half a winding loop W1 and a secondary winding W2. The primary conductor P is formed by the connecting line L2 and has only a few winding loops W1, e.g., three (N1 = 3) winding loops W1, while the number of turns N2 of the secondary winding W2 is greater than the number N1 of winding loops W1. Thus, if the number N1 = 3, the number of turns N2 of the secondary winding W2 is, for example, 30.

[0034] The secondary winding W2 is strongly inductively coupled to the primary conductor P via the magnetic core MK. Consequently, the inductance of the secondary winding W2 depends on the condition of the electrical transmission path 4, i.e., whether there is a defect, such as a break in the electrical connecting line L1 and / or the electrical connecting line L2. Therefore, the secondary winding W2 is also referred to as the measuring inductance L. The coupling of the secondary winding W2 to the primary conductor P depends on the geometry and material of the magnetic core MK and on the arrangement of the primary conductor P and the secondary winding W2.

[0035] The primary conductor has only a few winding loops W1; in the simplest case, the primary conductor P consists merely of a straight section of the connecting line L2. This ensures that the primary conductor P has a low resistance, i.e., is in the range of 100 mΩ or below. Consequently, the transformer formed by the magnetic core MK together with the primary conductor P and the secondary winding W2 has no negative influence on the function of the electrical arrangement 1, particularly because the loop impedance of the primary conductor P remains very small in the fault-free case of the electrical transmission path 4, i.e., when no defect is present.

[0036] As a further means of detecting a defect, e.g., a break in one of the two connecting lines L1 or L2, a diagnostic device 5 is provided, which is connected to the secondary winding W2 as a measuring inductance L and with which an inductance-dependent measurement signal LM generated by the measuring inductance L is evaluated to distinguish between a fault state and a non-fault state of the redundant electrical transmission path 4. For this purpose, the inductance-dependent measurement signal LM is compared with a fault threshold.

[0037] If there is no defect, i.e., the non-fault state of the two electrical connecting lines L1 and L2, and thus the redundancy of the transmission path 4 is present, the inductance-dependent measurement signal LM indicates a low inductance, which is therefore smaller than the fault threshold.

[0038] If, on the other hand, one of the two electrical connecting lines L1 and L2 has a defect, in particular a line break as a fault condition, i.e. the redundancy of the transmission path 4 is not present, a high inductance is indicated by the inductance-dependent measurement signal LM, which is therefore greater than the fault threshold.

[0039] There are various methods for generating the inductance-dependent measurement signal LM.

[0040] One way to generate an inductance-dependent measurement signal LM is to apply a known AC voltage to the measurement inductance L and evaluate the resulting AC current as the inductance-dependent measurement signal LM. The reactance, determined from the amplitude and phase of the measured AC current, is used as a reference value and compared to the fault threshold. If the reference value is less than the fault threshold, the transmission path 4 is in a non-fault state, i.e., there is no line break. Conversely, if the reference value is greater than the fault threshold, a fault state exists, such as a line break in one of the two electrical connecting lines L1 or L2 of the transmission path 4.

[0041] The diagnostic device 5 thus has the property that, depending on the evaluated inductance-dependent measurement signal LM, the state of the transmission path 4 is displayed, i.e., whether a line break is present or not, i.e., either "redundancy present" or "redundancy not present".

[0042] Another method for generating the inductance-dependent measurement signal LM involves determining the attenuation behavior of a low-pass or high-pass filter constructed with the secondary winding W2. From the inductance-dependent measurement signal LM, which indicates the attenuation behavior, an attenuation value is determined as a reference value and compared with a suitably appropriate error threshold.

[0043] If the attenuation value is less than the fault threshold, the inductance-dependent measurement signal LM indicates a low inductance of the measured inductance L, meaning there is no fault condition, i.e., no defect, e.g., a line break in transmission path 4. Conversely, if the attenuation value is above the fault threshold, the inductance-dependent measurement signal indicates a high inductance, meaning there is a fault condition, i.e., a defect, e.g., a line break in transmission path 4.

[0044] Another method for generating the inductance-dependent measurement signal LM consists of constructing an LC resonant circuit with the measurement inductance L, so that its resonance behavior is displayed with the inductance-dependent measurement signal LM and the resonant frequency is determined from this as a reference value in order to be compared with a suitably appropriate error threshold.

[0045] Finally, signal distortions of a control signal with multiple frequency components applied to the measuring inductance L can also be detected and evaluated using the inductance-dependent measurement signal LM. In particular, the time course during the switching on and / or off of the secondary winding can be recorded and evaluated with regard to the transient processes and / or the decay processes.

[0046] This method can be implemented, for example, by applying a control signal, shaped as a square wave, to the measuring inductance L. The edge waveform generated by the control signal is recorded as an inductance-dependent measurement signal LM, and the distortion level of the control signal's edge waveform is evaluated, since this distortion level depends on the inductance LM of the measuring inductance L and thus on the state of the two electrical connecting lines L1 and L2. The distortion level is then compared to a suitable error threshold value.

[0047] If the distortion level is less than the error threshold, the inductance-dependent measurement signal LM indicates a low inductance of the measured inductance L, meaning there is no fault condition, i.e., no defect, e.g., a line break in transmission path 4. Conversely, if the distortion level exceeds the error threshold, the inductance-dependent measurement signal indicates a high inductance, meaning there is a fault condition, i.e., a defect, e.g., a line break in transmission path 4.

[0048] Depending on the determined distortion level of the control signal, the state of the two electrical connecting lines L1 and L2 is displayed, i.e., whether there is a line break or not, meaning either "redundancy present" or "redundancy not present".

[0049] The Figure 2 shows an electrical arrangement 1 according to Figure 1, however, without the two electrical devices 2 and 3, wherein the transformer formed by the magnetic core MK together with the primary conductor P and the secondary winding W2 shows a detailed structure. The signal or power direction of the redundant electrical transmission path 4 is indicated by the reference symbol R.

[0050] According to Figure 2 The magnetic core MK is designed as a toroidal core and encloses the conductor L2 of the redundant electrical transmission path 4. Thus, the primary conductor P consists of only half a winding loop W1, which is a straight segment of the electrical connecting conductor L1. The secondary winding W2, arranged on the toroidal magnetic core MK, has a greater number of turns N2 than the number of turns N1 of the primary conductor P (e.g., 10 turns).

[0051] Even the Figure 3 shows an electrical arrangement according to Figure 1, however, without the two electrical devices 2 and 3. Also in this Figure 3 The signal or power direction of the redundant electrical transmission path 4 is indicated by the reference symbol R.

[0052] The means for detecting a fault state or a non-fault state in this electrical arrangement comprise 1 according to Figure 3 also a magnetic core MK with a primary conductor P with several winding loops W1 and a secondary winding W2 with a number of turns N2 that is greater than the number of turns N1 of the primary conductor P, and a diagnostic device 5.

[0053] The difference of electrical arrangement 1 according to Figure 3 to the one after Figure 1The arrangement consists of the two electrical connecting lines L1 and L2 being connected at their ends to a winding end of the winding loops W1, and a center tap M forming the node K1, which is electrically connected to a second electrical device (not shown). The node K1 is configured according to electrical arrangement 1. Figure 1 connected to a first electrical device. Reference symbol list

[0054] 1 Electrical arrangement 2 First electrical device 3 Second electrical device 4 Redundant electrical transmission path 5 Diagnostic device K1 node K2 node L1 electrical connection line L2 electrical connection line MK magnetic core N1 Number of winding loops W1 N2 Number of turns of the secondary winding W2 Center tap of the winding loop W1 Primary Head RSignal or power direction W1 Primary winding loop P W2 Secondary winding

Claims

1. Electrical arrangement (1) comprising - a first electrical device (2), - a second electrical device (3), - a redundant electrical transmission path (4) comprising two electrical connection lines (L1, L2), connected in parallel, between the first electrical device (2) and the second electrical device (3), characterised by the following features: - means (MK, W1, W2, 5) for detecting an error state of the redundant electrical transmission path (4), comprising - a magnet core (MK) having a low-ohmic primary conductor (P) in the region of 100 mΩ or less having at least half a winding loop (W1) up to three winding loops (W1), wherein the primary conductor (P) is formed only by one of the two connection lines (L1, L2), and having a secondary winding (W2) having a winding number (N2) greater than the number (N1) of the winding loops (W1) of the primary conductor (P), wherein the secondary winding (W2) is strongly inductively coupled to the primary conductor (P) via the magnet core (MK), and - a diagnosis device (5) for evaluating an inductance-dependent measuring signal of the secondary winding (W2), wherein - the diagnosis device (5) is configured to compare the inductance-dependent measuring signals (LM) of the secondary winding (W2) with a comparative value, in particular an error threshold value, that can be used for distinguishing between the error state and a non-error state of the redundant electrical transmission path (4).

2. Electrical arrangement (1) according to claim 1, in which the primary conductor (P) is configured to be lower-ohmic than the secondary winding (W2).

3. Electrical arrangement (1) according to either claim 1 or claim 2, in which the connection lines (L1, L2) are configured as supply lines for energy supply.

4. Electrical arrangement (1) according to any of claims 1 to 3, in which the connection lines (L1, L2) are configured as signal lines.

5. Electrical arrangement (1) according to any of claims 1 to 4, in which the comparative value is a measure for the temporal change in the measuring signal.

6. Method for detecting an error state of a redundant electrical transmission path (4) comprising an electrical arrangement according to any of claims 1 to 5, comprising the method steps of: - generating an inductance-dependent measuring signal (LM) of the measuring inductance (L), - evaluating the inductance-dependent measuring signal (LM) for distinguishing an error state from a non-error state of the redundant electrical transmission path (4), in that the inductance-dependent measuring signal (LM) of the measuring inductance (L) is compared with a comparative value, in particular an error threshold value, that can be used for distinguishing between the error state and a non-error state of the redundant electrical transmission path (4), - indicating that a non-error state is present if the inductance-dependent measuring signal (LM) (LM) is smaller than the comparative value, and - indicating that there is an error state in one of the connection lines (L1, L2) if the inductance-dependent measuring signal (LM) (LM) is greater than the comparative value.

7. Method according to claim 6, in which a damping value of an RL low-pass filter or RL high-pass filter or LC filter formed by means of the secondary winding (W2) is determined as the inductance-dependent measuring signal (LM).

8. Method according to claim 6, in which a resonant frequency of a resonant circuit formed by means of the secondary winding (W2) is determined as the inductance-dependent measuring signal (LM).

9. Method according to claim 6, in which the signal deformation of a control signal applied to the secondary winding (W2), having a plurality of frequency components, is determined as the inductance-dependent measuring signals (LM).