DE102024120056A1 - Measuring setup for the electrical system of a motor vehicle, electrical system, motor vehicle - Google Patents

Abstract

Measuring arrangement for a vehicle electrical system comprising an electronic fuse with a transistor, wherein the measuring arrangement is configured to be connected in parallel to a supply line protected by the electronic fuse for supplying electrical energy to the vehicle electrical system and/or a component of the vehicle electrical system; the measuring arrangement includes a capacitor; and the capacitor is connected in such a way that a change over time of a current flowing in a predetermined switching state of the transistor with a defined ohmic resistance causes a capacitor voltage that is quantitatively related to the change over time of the current.

Description

The present disclosure relates to a measuring arrangement for the electrical system of a motor vehicle. The disclosure relates equally to an electrical system for a motor vehicle and to a motor vehicle.

It is known from the prior art to equip motor vehicles with analog measuring technology in order to monitor the vehicle's electrical system, a component of the electrical system, and/or components of the component. This allows for the measurement of voltages at various locations or measuring points in the electrical system, the current draw of, for example, one or more of the components, and the temperature of electrical supply lines.

Especially when it comes to measuring current and voltage, comparatively high sampling rates may be necessary to accurately capture dynamic processes and/or transients. However, dynamic processes relevant to the design of the vehicle's electrical system do not occur continuously during vehicle operation, such as throughout an entire journey, but rather during short-term peak load scenarios and/or load changes.

WO 2023/174631 A1 Disclosure reveals an electrified motor vehicle comprising a high-voltage storage device, at least one electric motor, power electronics, a DC/DC converter, and an electronic evaluation unit for centralized, component-specific energy monitoring of defined components of a low-voltage electrical system and/or defined components of a high-voltage electrical system. The evaluation unit is designed such that a specific load signature is stored for each defined component. A total measurement signal, acquired outside the defined components by a first (single) sensor for the entire low-voltage electrical system and/or a second (single) sensor for the entire high-voltage electrical system, is disaggregated using NILM technology to identify the load signatures. Furthermore, the respective total measurement signal is cleaned of vehicle-specific electrical disturbances by a defined correction module before disaggregation.

Conventionally, measurements are triggered by threshold values, for example in oscilloscopes. When a threshold value is exceeded, a measurement recording is started.

Triggering based on digital processes, e.g., due to a discrete derivation of a measurement signal and/or a specific algorithm, is also known. However, the sampling rate chosen for these dynamic processes leads to measurements being taken at the comparatively high sampling rate even in less dynamic processes and/or in steady-state or quasi-steady-state conditions. This results in an unnecessarily large amount of data overall, since the comparatively high sampling rate is too high for less dynamic processes and/or measurements at the comparatively high sampling rate yield insufficient useful information for less dynamic processes. Therefore, it is beneficial to dynamically adjust the sampling rate to reduce the amount of data.

However, a digital implementation of dynamic sampling rate adjustment does not necessarily appear to be the most effective approach. Due to the computation time of digital implementations, a digital implementation of dynamic adjustment exhibits a comparatively high response time or inertia, which can, for example, make the detection of steep edges in the measurement signal more difficult and/or delay it, and can also delay a dynamic increase in the sampling rate. Furthermore, the digital implementation depends on a selected base sampling rate or a minimum sampling rate. Pure threshold detection neglects highly dynamic component loads in the low power range, while loads in the high power range are recorded with high resolution regardless of their dynamics.

The German patent application, which had not yet been published on the filing date of the present disclosure, bears the official file number DE 10 2024 104 769.0 Disclosing a measuring arrangement for the electrical system of a motor vehicle, the measuring arrangement comprises: a supply line for supplying electrical energy to the electrical system and/or a component of the electrical system; a component designed as an inductor or capacitor; an ohmic measuring resistor connected in series with the component; a comparator, wherein the comparator is configured to compare a measuring voltage applied to the measuring resistor with a reference voltage and then output a comparison signal; and a data processing device, wherein the data processing device is configured to adjust a sampling rate on the basis of the comparison signal; wherein the component is connected to the supply line in such a way that a change over time of an electrical quantity characterizing the electrical energy causes a change in the measuring voltage.

A defined measuring resistor is used to obtain reliable measurement results.

Against the background of this prior art, one objective of the present disclosure is to provide a device suitable for enriching the prior art and improving at least the aforementioned aspects of the prior art. In particular, the disclosure aims to reliably, precisely, and cost-effectively measure changes in current in the supply line.

The problem is solved by the features of the independent claims. The dependent claims contain further developments of the disclosure.

The problem is then solved according to one aspect of the disclosure by a measuring arrangement for a vehicle electrical system comprising an electronic fuse with a transistor, wherein the measuring arrangement is configured to be connected in parallel to a supply line protected by the electronic fuse for supplying electrical energy to the vehicle electrical system and/or a component of the vehicle electrical system; the measuring arrangement includes a capacitor; and the capacitor is connected in such a way that a change over time of a current flowing in a predetermined switching state of the transistor with a defined ohmic resistance causes a capacitor voltage that is quantitatively related to the change over time of the current.

It was discovered that the capacitor can provide a response to a change in current in the supply line, reflected by the capacitor voltage. The current in the supply line is equal to the current through the transistor, since the supply line is protected by the electrical fuse. The transistor exhibits ohmic resistance. A relatively rapid change in current can be translated into a relatively high capacitor voltage, while a relatively slow change in current can be translated into a relatively low capacitor voltage. The fundamental detection of the edges is thus based on the capacitor voltage across a known capacitor, which in turn is based on a change in current in the transistor of the electronic fuse.

Therefore, the dynamics can be reliably and accurately inferred from the capacitor voltage. A sampling rate can thus be chosen, for example, as proportional to the capacitor voltage and/or a derived quantity, in order to achieve a higher sampling rate at higher capacitor voltages, which indicate faster dynamics, than at lower capacitor voltages, which indicate slower dynamics. This eliminates the need to define a basic sampling rate. This makes the measuring device more reliable and therefore more efficient. The disclosure enables dynamic adjustment of the sampling rate, particularly based on transient current changes. The implementation is analogous. This allows for rapid changes or adjustments to the sampling rate.

Conventional current measurement methods often use additional measuring resistors, such as a shunt. Utilizing the transistor's internal resistance eliminates the need for such resistors. By using the transistor's internal resistance, for example, that of a field-effect transistor, no additional components are required in the vehicle's wiring harness or power supply. This avoids the need for additional installation space and minimizes resistive and reactive interference with the vehicle's electrical system. As a result, high specified safety integrity levels (ASIL) for safety-related systems in vehicles can be effectively achieved.

Furthermore, it was recognized that motor vehicles, including prototypes, pre-production vehicles, and production vehicles, can be equipped with such a measuring arrangement relatively easily. One exemplary application is an electronic fuse (so-called "E-Fuse") capable of acquiring measurement data at an adjustable sampling rate. This enables the acquisition of dynamic measurement data from the vehicle's electrical system.

Dynamic adjustment allows the sampling rate to be increased for more dynamic signals and decreased for less dynamic signals. This enables improved design of the vehicle's electrical system and/or components, despite a significantly reduced data volume, and/or allows for more reliable and comprehensive monitoring during vehicle operation. This is particularly relevant in customer operation or in production vehicles, as data loggers cannot typically be installed to store large amounts of data, and transmitting measurement data, for example via a mobile network, is comparatively expensive.

Optionally, the predetermined switching state is a conducting state and/or a saturation state. It was recognized that, in particular, a A field-effect transistor in the conducting state and/or the saturation state exhibits a defined ohmic resistance, and in particular these switching states allow a well-defined determination of the current dynamics.

Optionally, the measuring setup includes a first measuring amplifier to amplify the initial voltage drop across the transistor caused by the current and the transistor's ohmic resistance. It was observed that the current through the transistor typically results in a comparatively small voltage drop. Amplifying this initial voltage can thus be used to charge and/or discharge the capacitor, enabling a reliable representation of the current dynamics.

Optionally, the measuring arrangement includes an inverting differentiator and an inverting amplifier; the inverting differentiator and the inverting amplifier are connected such that a time-dependent change in current is mapped as a function of its sign. This allows the time-dependent change in current to be mapped, depending on its sign, into an interval encompassing negative and positive voltages. The sign of the voltage can then represent the sign of the time derivative of the current.

Optionally, the measuring arrangement includes a non-inverting differentiator and an instrumentation amplifier; the non-inverting differentiator and the instrumentation amplifier are connected such that a time-dependent change in current is mapped to a voltage range of the same sign. This allows the time-dependent change in current to be mapped, regardless of sign, to an interval encompassing, for example, positive voltages. The sign of the time derivative of the current can be represented by an upper and a lower half of the interval.

Optionally, the measuring arrangement includes a comparator configured to output a comparison signal based on a third voltage derived from the capacitor voltage and a reference voltage. The comparator can be used to provide a binary comparison signal for further digital processing. Optionally, the measuring arrangement includes an optocoupler for galvanic isolation.

Optionally, the measuring arrangement includes a data processing device configured to adjust the sampling rate based on the reference signal. The data processing device dynamically adjusts the sampling rate, particularly based on transient changes in the supply current. This adjustment is implemented analogously by the measuring arrangement. This enables rapid changes or adjustments to the sampling rate.

According to one aspect of the disclosure, an electrical system for a motor vehicle is provided, comprising an electronic fuse with a transistor and at least one measuring arrangement as described above. Optionally, the measuring arrangement has one or more features described as advantageous and/or optional in order to achieve an associated technical effect. It was also recognized that the electrical system can optionally have several different measuring arrangements, for example, a measuring arrangement for monitoring the electrical system and a measuring arrangement for monitoring a component.

Optionally, the vehicle electrical system can be designed as a low-voltage system. It has been found that low-voltage systems can be monitored particularly effectively, especially when they include electronic fuses for monitoring, and the sampling rate of these fuses is influenced by the measurement setup.

According to one aspect of the disclosure, a motor vehicle comprising the electrical system described above is provided. Optionally, the electrical system and/or its measuring arrangement has one or more features described as advantageous and/or optional in order to achieve an associated technical effect.

• 1 zeigt schematisch ein Kraftfahrzeug gemäß einem Aspekt der Offenbarung;
• 2 zeigt schematisch eine Messanordnung gemäß einem Aspekt der Offenbarung; und
• 3 zeigt schematisch eine Messanordnung gemäß einem Aspekt der Offenbarung.

One embodiment of each is described below with reference to the figures.

• 1 schematically depicts a motor vehicle according to one aspect of the revelation;
• 2 schematically shows a measuring arrangement according to one aspect of the revelation; and
• 3 schematically shows a measuring arrangement according to one aspect of the revelation.

1 schematically shows a motor vehicle 50 according to one aspect of the revelation.

Motor vehicle 50 is a land vehicle. Motor vehicle 50 is a passenger car.

The motor vehicle 50 has an on-board electrical system 61 designed as a low-voltage network 60. The low-voltage network 60, or low-voltage system, is designed, for example, to operate with alternating voltages up to and including 30 V or direct current. to be operated at voltages up to and including 60 V. The low-voltage network 60 comprises an electronic measuring device designed as an electronic fuse 53 (“E-Fuse”) and a component 65. In another embodiment (not shown), the motor vehicle 50 may have a different number of electronic measuring devices and/or components 65 than shown.

Component 65 can, for example, comprise or be a sensor, an actuator, and/or a control unit. Component 65 is designed to be supplied with electrical energy or, more precisely, to be subjected to a current when a voltage is applied. Component 65 comprises a plurality of components (not shown). These components are electrically interconnected and can therefore influence each other and determine the function of component 65.

The electronic fuse 53 is designed to electrically protect the component 65, i.e., to protect it against excessive currents and/or voltages. The electronic fuse 53 is designed to measure a time-dependent input current signal, a time-dependent input voltage signal, and optionally a time-dependent temperature signal pertaining to the component 65. The input current signal represents, for example, the current I with which the component 65 is supplied via a supply line 71 (see 2 and 3 The electronic fuse 53 is configured to perform measurements of the measured quantities at a sampling rate FS. The sampling rate FS specifies the number of measurements per unit of time, for example, in measurements per second. The electronic fuse 53 includes and/or is communicatively connected to a data processing device 51 (not shown), which is configured to control the measurements by the electronic fuse 53 and, in particular, to change or adjust the sampling rate FS.

The motor vehicle 50 or the on-board network 61 has a measuring arrangement 70, which is described in detail with reference to 2 and 3 The measuring arrangement 70 includes the data processing device 51 (not in 2 and 3 shown) wherein the data processing device 51 is configured to use a comparison signal 80 (see also 2 and 3 ) to adjust a sampling rate FS.

2 Figure 70 schematically shows a measuring arrangement 70 according to one aspect of the disclosure. The measuring arrangement 70 according to 2 is a measuring arrangement 70 for an on-board electrical system 61 of a motor vehicle 50. Such a motor vehicle 50 and such an on-board electrical system 61 are related to 1 described. 2 will be with reference to 1 described.

The measuring arrangement 70 according to 2 is designed to be connected in parallel to a supply line 71, protected by the electronic fuse 53, for supplying electrical energy to the vehicle electrical system 61 and/or component 65 of the vehicle electrical system 61. The supply line 71 is therefore designed to supply electrical energy to the vehicle electrical system 61. The vehicle electrical system 61 can supply one or more components 65 (see 1 ) include those in 2 are not shown.

The electronic fuse 53 (see 1 ) features a transistor 53a with an ohmic resistance RS (in 2 and 3 (Only the ohmic resistance RS is shown in the circuit diagram). The ohmic resistance RS of transistor 53a is used as a measuring resistor. Transistor 53a is, for example, a field-effect transistor. Transistor 53a is designed to be electrically switched and thus brought into different switching states. For example, transistor 53a is designed to be switched to a cut-off state and to a conducting state, which can transition into a saturation state. The resistance of transistor 53a, or rather its ohmic resistance RS, depends on the switching state. This dependency can be found, for example, in the datasheet for transistor 53a.

The measuring arrangement 70 includes a capacitor 72. The capacitor 72 has a capacitance C. The capacitor 72 is connected such that a change in the current I flowing in the predetermined switching state of the transistor 53a with a defined ohmic resistance RS causes a capacitor voltage VB that is quantitatively related to the change in current I.

For this purpose, the measuring arrangement 70 according to 2 a first measuring amplifier 76. The first measuring amplifier 76 is designed to amplify a first voltage VA across transistor 53a, which is determined by the current I and the ohmic resistance RS of transistor 53a. The first voltage VA is amplified by a gain factor v_INA that defines the measuring amplifier 76. This results in the following formula for the first voltage VA = RS x I x v_INA. The voltage drop across the ohmic resistance RS is thus amplified to the first voltage VA by the gain factor v_INA.

The measuring arrangement 70 optionally includes a first resistor R1. The first resistor R1 is connected between the capacitor 72 and the first measuring amplifier 76.

The measuring arrangement 70 comprises an inverting differentiator 77a and an inverting amplifier 77b. The inverting differentiator 77a and the inverting amplifier 77b are connected such that a change in the current I over time is represented as a sign-dependent function. The capacitor 72 is connected between one input of the inverting differentiator 77a and the first measuring amplifier 76. The other input of the inverting differentiator 77a is connected to ground. The measuring arrangement 70 has a second resistor R2 in parallel with the inverting differentiator 77a. This results in the following equation for the capacitor voltage VB, which can be tapped after the inverting differentiator 77a: VB = -R2 x C x dVA / dt, where d / dt is the derivative with respect to time. The capacitor voltage VB is therefore inversely proportional to the change in the first voltage VA over time and thus to the current I.

The measuring setup 70 has a third resistor R3 and a fourth resistor R4. The third resistor R3 is connected between the inverting differentiator 77a and the inverting amplifier 77b, and the fourth resistor R5 is connected in parallel with the inverting amplifier 77b. This amplifies the capacitor voltage VB, resulting in a third voltage VC = -R4/R3 x VB, which can be tapped after the inverting amplifier 77b. Due to the two sign changes when determining the capacitor voltage VB and the third voltage VC, the third voltage VC has the same sign as the time-dependent change of the current I.

The measuring arrangement 70 includes a comparator 74. The comparator 74 is configured to output a comparison signal 80 based on the third voltage VC, which is based on the capacitor voltage VB, and a reference voltage VRef.

The measuring arrangement 70 enables the third voltage VC to be mapped, with correct sign, into an interval from -U0 to U0 with the mains voltage U0 of, for example, 5V. Thus, a reference voltage VRef of 0V can, for example, represent the sign of the change in current I over time, i.e., an increase or a decrease in the current. A dynamic change can be indicated by a reference voltage VRef other than 0V. The measuring arrangement 70 according to 2 It is sensitive and can be implemented cost-effectively.

3 Figure 70 schematically shows a measuring arrangement 70 according to one aspect of the disclosure. The measuring arrangement 70 according to 3 is a measuring arrangement 70 for an on-board electrical system 61 of a motor vehicle 50. Such a motor vehicle 50 and such an on-board electrical system 61 are related to 1 described. 3 will be with reference to 1 described. The measuring arrangement 70 according to 3 is an alternative to the measurement setup according to 2 The differences between the measurement setups 70 are described below. 2 and 3 described.

The measuring arrangement 70 according to 3 The instrumentation 70 comprises a non-inverting differentiator 78a and an instrumentation amplifier 78b. The non-inverting differentiator 78a and the instrumentation amplifier 78b are connected such that a change in the current I over time is mapped to a voltage range of the same sign. For this purpose, the instrumentation 70 includes a first resistor R1. The non-inverting differentiator 78a, the first resistor R1, and the capacitor 72 are connected such that the capacitor voltage VB is calculated as follows: VB = R1 x C x dVA / dt. The instrumentation amplifier 78b defines a gain factor v_INA. The instrumentation amplifier 78b is connected such that the capacitor voltage VB across the first resistor R1 is amplified by the instrumentation amplifier 78b. This results in a third voltage VC = VB x v_INA, which can be tapped after the instrumentation amplifier 78b. The third voltage, VC, has a value within the interval from 0V up to the mains voltage U0, for example, 5V. The change in current I over time is thus mapped to the interval from 0V up to the mains voltage U0. The implementation of the measuring arrangement 70 according to 3 This is effectively possible because the non-inverting differentiator 78a and the instrumentation amplifier 78b only require one supply voltage.

Reference symbol (part of the description)

50

motor vehicle

51

Data processing device

53

electronic fuse

53a

transistor

60

Low-voltage network

61

On-board electrical system

65

component

70

Measuring setup

71

supply line

72

capacitor

74

Comparator

75

Differential amplifier

76

first measuring amplifier

77a

inverting differentiator

77b

inverting amplifier

78a

non-inverting differentiator

78b

Instrument amplifier

80

Comparison signal

C

capacity

FS

Sampling rate

I

electrical quantity, current

R1

first resistance

R2

second resistance

R3

third resistance

R4

fourth resistance

RS

ohmic resistance of the transistor

U

electrical quantity, voltage

U0

Mains voltage

VA

first tension

VB

Capacitor voltage, second voltage

VC

third tension

VRef

Reference voltage

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2023/174631 A1 [0004]
• DE 10 2024 104 769.0 [0008]

Claims (10)

Measuring arrangement (70) for an electrical system (61) of a motor vehicle (50) comprising an electronic fuse (53) with a transistor (53a), wherein: - the measuring arrangement (70) is configured to be connected in parallel to a supply line (71) protected by the electronic fuse (53) for supplying electrical energy to the electrical system (61) and/or a component (65) of the electrical system (61); - the measuring arrangement (70) comprises a capacitor (72); and - the capacitor (72) is connected such that a change over time of a current (I) flowing in a predetermined switching state of the transistor (53a) with a defined ohmic resistance (RS) causes a capacitor voltage (VB) that is quantitatively related to the change over time of the current (I). Measuring setup (70) according to Claim 1 , where the predetermined switching state is a conducting state and/or a saturation state. Measuring setup (70) according to Claim 1 or 2 , wherein the measuring arrangement (70) comprises a first measuring amplifier (76) for amplifying a first voltage (VA) across the transistor (53a) due to the current (I) and the ohmic resistance (RS) of the transistor (53a). Measuring arrangement (70) according to one of the preceding claims, wherein - the measuring arrangement (70) comprises an inverting differentiator (77a) and an inverting amplifier (77b); and - the inverting differentiator (77a) and the inverting amplifier (77b) are connected such that a change in current (I) over time is represented as a sign-dependent change. Measuring arrangement (70) according to one of the preceding claims, wherein - the measuring arrangement (70) comprises a non-inverting differentiator (78a) and an instrumentation amplifier (78b); and - the non-inverting differentiator (78a) and the instrumentation amplifier (78b) are interconnected such that a change in current (I) over time is mapped to a voltage range of the same sign. Measuring arrangement (70) according to one of the preceding claims, wherein - the measuring arrangement (70) comprises a comparator (74); and - the comparator (74) is configured to output a comparison signal (80) based on a third voltage (VC) based on the capacitor voltage (VB) and a reference voltage (VRef). Measuring setup (70) according to Claim 6 , wherein the measuring arrangement (70) comprises a data processing device (51), wherein the data processing device (51) is configured to adjust a sampling rate (FS) using the comparison signal (80). On-board electrical system (61) for a motor vehicle (50), comprising an electronic fuse (53) with a transistor (53a) and at least one measuring arrangement (70) according to one of the preceding claims. On-board electrical system (61) after Claim 8 , wherein the on-board network (61) is designed as a low-voltage network (60). motor vehicle (50), comprising the on-board electrical system (61) according to Claim 8 or 9 .