CN110780103A

CN110780103A - Measuring device

Info

Publication number: CN110780103A
Application number: CN201910705257.XA
Authority: CN
Inventors: W·席曼; N·德拉斯
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2018-07-31
Filing date: 2019-07-31
Publication date: 2020-02-11
Also published as: FR3084749A1; DE102018212763A1

Abstract

The invention relates to a measuring device for measuring a current in a vehicle electrical system and to a method for measuring a current in a vehicle electrical system. The transmission characteristic of the measuring device is changed during the measurement by means of a first adjustment.

Description

Measuring device

Technical Field

The invention relates to a measuring device for measuring a current in a vehicle electrical system and to a method for measuring a current, in particular by means of the measuring device. The measuring device is also referred to as a current measuring device.

Background

"on-board network" is understood to mean the totality of all electrical components in the motor vehicle during use of the vehicle. The on-board network therefore includes not only the electrical consumer but also a power supply source (for example a battery). In this case, a distinction is made between the energy supply system and the communication system, wherein the energy supply system responsible for supplying the components of the motor vehicle with energy is first considered here. In order to control the on-board system, a microcontroller is usually provided, which, in addition to the control function, also performs a monitoring function.

In motor vehicles, it should be noted that: the electrical energy can be supplied in such a way that the motor vehicle can be started at any time and sufficient electrical energy is available during operation. Even in the off state, the appliance should still be able to operate for a suitable period of time without affecting the subsequent start-up.

Due to the increasing electrification of the assemblies (aggregats) and the introduction of new vehicle functions (for example automatic driving, highly automatic driving or autonomous driving), the demands on the reliability of the electrical energy supply in the motor vehicle are increasing. In this context, it should be noted in particular that: the number of power electrical systems continues to increase. If one of these systems fails, it may happen that the on-board network voltage falls outside the normal operating range, which may lead to a failure of the component and thus to an impairment of the safety of the vehicle occupants.

In vehicles which allow partially automated driving or highly automated driving, special requirements are placed on the electrical supply of safety-relevant components (e.g. steering, braking, etc.). Since other safety-related components also operate on the same power supply, it is necessary either to separate the two regions from each other or to monitor the individual participating components from each other. The current measuring device is given particular significance here. The current measuring device should ensure that: the individual components do not draw impermissibly high currents from the on-board system and in this way endanger the power supply of the safety-relevant system. For this purpose, it must be ensured that the current measuring device also works reliably.

One known solution is arranged as follows: two current measuring devices are used which are independent of one another. Furthermore, to ensure that there are no systematic errors, multiple redundancy schemes may be used. The disadvantage of this solution is the high cost. In the case of a multiple redundancy solution, development costs are additionally increased.

Disclosure of Invention

Against this background, a measuring device according to the invention and a method according to the invention are proposed. The implementation mode follows from the description.

A measuring device for current measurement is therefore proposed, the transmission characteristics of which are changed during the measurement by different measures, i.e. the transmission characteristics can be manipulated (manipulieren) or adjusted (moduleieren). Thus, the measuring device changes its characteristics during the measurement.

The change or adjustment can be effected by an electrical switch in the measuring path. The adjustment of the transmission characteristic can be carried out, for example, at high frequencies, but still within the transmission range of the measuring device. Furthermore, a second adjustment can be made, which has an opposite effect to the first adjustment and can be made functionally dependent (i.e. temporally dependent) on the first adjustment.

Both adjustments can be eliminated in at least one operating point.

Furthermore, in the case of this measuring device, a plurality of measuring channels can be used simultaneously.

The measuring device can have, for example, a measuring resistor or shunt or a semiconductor segment as a measuring element.

Furthermore, the entire measurement chain may be implemented within an integrated module, such as an Application Specific Integrated Circuit (ASIC). Further, the impact of the process adjustments on the system can be analyzed statistically. This is used to check the functionality of the measurement chain.

It should be noted that: the proposed solution uses only a unique measurement path for each measurement signal to avoid these costs.

The solution proposed here uses a self-check (Selbst ü berpr ü fang) of the measuring device which operates continuously during operation in order to achieve a high level of safety in the configuration.

The proposed method is used for measuring the current in an on-board network, typically the on-board network of a motor vehicle. The method is carried out by means of a measuring device, in particular of the type described here. In the case of this method, the measuring device is manipulated or adjusted during the measurement as follows: the transmission characteristics of the measuring device are changed.

Further advantages and configurations of the invention emerge from the description and the figures.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or individually without leaving the scope of the present invention.

Drawings

Fig. 1 shows an embodiment of the described measuring device in a block diagram;

fig. 2 graphically illustrates an example of analyzing a measurement signal in processing a noise signal.

Detailed Description

The invention is described schematically according to embodiments in the drawings and in the following in detail with reference to the drawings.

Fig. 1 shows an embodiment of a current measuring device, which is designated as a whole by reference numeral 10 and which can be adjusted at different points and thus checked for correct functioning.

The figure shows one possible structure of the proposed current measuring device. Starting from right to left is the supply area to be protected, which is shown here as a battery 12. Two components follow, namely the load 14 and the current measuring sensor 16, which is embodied here as a power switch (Leistungsschalter). The further elements OP 120 and OP 222 act as so-called current mirrors (OP1) and as so-called buffers (OP 2).

Shown on the far left are OP 330 as a current source and OP 232 as a voltage source. The block 40 is functionally responsible for the power supply of the measuring device 10, the middle block 50 being the actual measuring device in combination with the measuring element or current measuring sensor 16 (in this case a power switch).

Starting now from the left side of fig. 1: OP 330 as current source inputs constant current Into branches R133, T135, R337, T239. The magnitude of the current is determined by the reference voltage at the positive input of OP 330 and the magnitude of R133.

The voltage at the apex of R337 (oberer Punkt) is also known, since the current through R337 is the same as that which had been previously determined by OP 330.

The voltage determined in the supply path (block 40) is now used in the measurement path (block 50) to generate a measurement signal therefrom. The same potential exists at the reference point of R841 as at the reference point of current sensor 16. If no current flows through the sensor 16, U _ DS is 0. Thus, the positive input of OP 120 is at the supply voltage.

In general, the current to be measured is represented as follows:

formula 1) I _Measurement＝(I _{Load (R)}*R _dsOn+V _{Reference to}*R3/R1)/R8

Or as a more meaningful voltage for further processing:

formula 2) U _Measuring＝(I _{Load (R)}*R _dsOn+V _{Reference to}*R3/R1)*R9/R8

There are now a number of possibilities in terms of circuit technology for influencing the measurement. For example, the switches shown in FIG. 1 are test 170, test 272, and test 374.

For example, it is proposed that a change in the selected measurement point ideally results in no change in the output value (e.g., S272). If there is a current zero (I) _{Load (R)}0), the result then depends only on the reference voltage V _{Reference to}And the ratio R3R 9/(R1R 8).

This means that: at this operating point V can be compensated for by reducing (closing S374) the R9 (reference numeral 57) path _{Reference to}Is raised (e.g., turning on S272). Since each of these measures will result in a distortion of the measurement results

Maintaining the result when both measures are used simultaneously therefore leads to a correct functioning of the entire measuring device.

After the method has been carried out with continued effective measurement, the corresponding effect can be corrected by calculation, but it cannot be expected that the load current remains constant or zero at all times during the actuation. The correctness of the previously mentioned conclusions can therefore only be inferred restrictively from the individual measurements.

Thus, the following current measuring device is used in the example shown: the measuring element of the current measuring device is embodied as a so-called shunt or measuring resistor or as a semiconductor section in the power switch. Such measuring devices are common and, depending on the application, also cost-effective. For functional reasons, the measuring elements are installed in the so-called High-Side path, which requires a higher outlay for configuring the measuring device.

Fig. 2 shows a graph 100 of an adjustment signal 102, an associated output signal 104 and an evaluation signal 106 (for example U) _Measuring) Superimposed with noise (i.e. the variation of the input current during the adjustment), the analytically processed signal is obtained after statistical analytically processing (i.e. the output signal 104 is superimposed n times) in synchronism with the input signal, respectively. In this signal, the correlation with the input signal 102 can be detected precisely (i.e., both time-discrete and value-discrete — in this case with a phase shift of 180 °).

It is therefore further proposed to treat the effects of the proposed changes in the measurement chain analytically by means of statistical methods.

Claims

1. A measuring device for measuring a current in an on-board network, the transmission characteristic of the measuring device being changed, i.e. manipulated or adjusted, during the measurement by a first adjustment.

2. Measuring device according to claim 1, wherein the first adjustment is made by means of at least one electrical switch (70, 72, 74) in the measuring path.

3. The measuring device according to claim 1 or 2, wherein the adjustment of the transmission characteristic can be performed within a transmission range of the measuring device (10).

4. A measuring device according to any one of claims 1 to 3, which is provided for making a second adjustment, which is counterproductive to and can be made functionally related to the first adjustment.

5. The measurement device according to claim 4, wherein the two adjustments are such that they are cancelled in at least one working point.

6. A measuring device according to any one of claims 1 to 5, arranged for using a plurality of measuring channels simultaneously.

7. The measurement device according to any of claims 1 to 6, which is implemented in an integrated module, such as an ASIC.

8. The measuring device according to any one of claims 1 to 7, which is provided for statistically analyzing the influence of the adjustment on the measuring device (10).

9. A method for measuring a current in an on-board network by means of a measuring device (10), the transmission characteristic of which is changed, i.e. manipulated or adjusted, during the measurement by means of a first adjustment.

10. The method according to claim 9, which is carried out by means of a measuring device (10) according to any one of claims 1 to 8.