阅读说明：本技术 用于模拟-数字转换的方法和设备、电网 (Method and device for analog-to-digital conversion, and power grid ) 是由 J.尤尔 于 2019-08-27 设计创作，主要内容包括：用于模拟-数字转换的方法和设备、电网。本发明涉及一种用于将模拟的、至少基本上连续的输入信号模拟-数字转换成数字输出信号的方法,所述输入信号具有被频率不同的至少两个干扰信号(S1、S2)叠加的有效信号,其中所述输入信号在有限的测量周期内被采样,而且其中在所述测量周期之内的多个采样点(A1-A5)的数目和时间点根据所述输入信号的频率来确定。规定：所述采样点(A1-A5)根据所述干扰信号(S1、S2)的频率来确定。(Method and device for analog-to-digital conversion, power network. The invention relates to a method for analog-to-digital conversion of an analog, at least substantially continuous input signal into a digital output signal, said input signal having a useful signal superimposed by at least two interfering signals (S1, S2) of different frequencies, wherein the input signal is sampled within a limited measuring period, and wherein the number and the point in time of a plurality of sampling points (A1-A5) within the measuring period are determined as a function of the frequency of the input signal. Stipulating: the sampling points (A1-A5) are determined according to the frequency of the interfering signal (S1, S2).)

1. A method for analog-to-digital conversion of an analog, at least substantially continuous, input signal into a digital output signal, the input signal having a valid signal superimposed by at least two interfering signals (S1, S2) of different frequencies, wherein the input signal is sampled within a limited measuring period, and wherein the number and the point in time of a plurality of sampling points (a 1-a 5) within the measuring period are determined depending on the frequency of the input signal, characterized in that the sampling points (a 1-a 5) are determined depending on the frequency of the interfering signals (S1, S2).

2. The method according to claim 1, characterized in that at least two sampling points (a 1, a 2) are determined from the frequency of the low frequency interference signal (S1) and at least two sampling points (A3-a 4) are determined from the frequency of the high frequency interference signal (S2).

3. Method according to one of the preceding claims, characterized in that at least four sampling points (a 1-a 4) are selected within one measurement period, of which the first sampling point (a 1) and the second sampling point (a 2) are selected at an interval of half and at least one full period duration of the glitch (S1).

4. The method as claimed in one of the preceding claims, characterized in that two sampling points (A3-A4) selected in dependence on the high-frequency interference signal (S2) are determined in dependence on the first and second sampling points (A1, A2).

5. Method according to one of the preceding claims, characterized in that the third sampling point (A3) is set at the half period duration before or after the first sampling point (a 1) of the high-frequency interference signal (S2), and the fourth sampling point (a 4) is set at the half period duration before or after the second sampling point (a 2) of the high-frequency interference signal (S2).

6. The method according to one of the preceding claims, characterized in that the fifth sampling point (a 5) is set one period duration before or after the third or fourth sampling point (A3, a 4) of the high-frequency interference signal (S2).

7. The method according to one of the preceding claims, characterized in that the frequency of the interfering signal (S1, S2) is determined in advance.

8. Device for carrying out the method according to one of claims 1 to 7, characterized by a control device which is specially prepared for carrying out the method according to one of claims 1 to 7 in normal use.

9. An electrical network, in particular an on-board electrical network or a traction network of a motor vehicle, characterized by a device according to claim 8.

Technical Field

The invention relates to a method for analog-to-digital conversion of an analog, at least substantially continuous, input signal into a digital output signal, the input signal having a useful signal superimposed by at least two interfering signals of different frequencies, wherein the input signal is sampled over a limited measuring period, and wherein the number and point in time of a plurality of sampling points within the measuring period are determined depending on the frequency of the input signal.

The invention also relates to a device for carrying out the above-mentioned method and to an electrical system, in particular an on-board electrical system or a traction electrical system of a motor vehicle, having such a device.

Background

Processes of the type mentioned at the outset are known from the prior art. Thus, for example, publication DE 2455302 a1 discloses a method for analog-to-digital conversion, in which an analog input signal is subjected to superimposed equidistant and at least pseudo-randomly varying sampling intervals with a limited sampling rate. Thus, an increased resolution of the analog input signal should be achieved without significantly increasing the cost of the installation. As is well known, the analog input signal is sampled under consideration of Shannon (Shannon) or Nyquist theorem. The shannon or nyquist theorem states that: the number of samples per measurement period must be greater than 2 and the number of samples per measurement period is an integer, such as is summarised in publication DE 102007043927 a 1. There is also proposed: an estimated frequency of the signal frequency is determined and the sampling frequency is determined from the estimated frequency and thereby ultimately from the reduced signal frequency. From publication US 5815101 a, a method for print digital conversion is also known, in which an input signal is sampled with a first sampling rate and with a second sampling rate.

In practice it has been shown that: for example, in the onboard power supply system of a motor vehicle, the power supply system is superimposed by interference signals, in particular in the region of the traction battery pack. When monitoring the battery cells, the battery voltage or the cell voltage is detected as an input signal. In this case, the voltage signal is often superimposed by two interference signals, which have different frequencies, so that a high-frequency interference signal and a low-frequency interference signal are mentioned.

If the signal is now sampled with equidistant sampling points during the measurement period, a relatively high measurement error results. The methods proposed in the prior art mentioned above do not satisfactorily reduce the measurement errors considerably.

Disclosure of Invention

The invention is therefore based on the task of: an improved method for analog-to-digital conversion is provided in which measurement errors are reduced to a minimum.

The object on which the invention is based is achieved by a method having the features of claim 1. The method results in: the measurement error during the analog-to-digital conversion is reduced to a minimum in a simple manner, wherein the number of total set samples does not have to exceed what has been possible to date. According to the invention, this is achieved by: the sampling point is determined according to the frequency of the interfering signal. These sampling points are thus coordinated and adapted to the interference signal, so that in particular the minima and maxima of the interference signal can be better detected, as a result of which measurement errors can be reduced.

According to a preferred embodiment of the invention, at least two sampling points are determined as a function of the frequency of the low-frequency interference signal and at least two sampling points are determined as a function of the frequency of the high-frequency interference signal. In this embodiment, a total of at least four sampling points are preferably specified, two sampling points being dependent on the low-frequency signal and two sampling points being dependent on the high-frequency control signal. The sampling points are determined in particular in accordance with the period duration of the respective interference signal. By using at least four sampling points, i.e. two for each of the interfering signals, a successful reduction of the measurement error is achieved. Since these sampling points are determined in dependence on the frequency of the interfering signal, a further reduction of the measurement error is achieved.

Preferably, four sampling points are selected for one measurement period, i.e. one measurement period is limited to four sampling points, wherein the first sampling point and the second sampling point are selected at an interval of half and at least one full period duration of the low frequency interference signal. Thus, the first and second sampling points are predetermined in accordance with the glitch and are spaced apart from one another by an interval corresponding to at least one and a half cycle duration, two and a half cycle duration, three and a half cycle duration, four and a half cycle duration, etc. of the glitch. The aim of this is to be able to detect the maximum and minimum values of the interference signal, thereby achieving an advantageous consideration of the low-frequency interference signal and thus reducing the measurement error.

Provision is also preferably made for: at least two sampling points selected according to the high-frequency interference signal are determined according to the first sampling point and the second sampling point. The other two sampling points are positioned in particular around the first and second sampling points in order to detect the high frequency interference signal in the vicinity of the maxima and minima of the low frequency interference signal. By this, the measurement error is further reduced.

Particularly preferably, the third sampling point is set at a half cycle duration of the high-frequency interference signal before or after the first sampling point, and the fourth sampling point is set at a half cycle duration of the high-frequency interference signal before or after the second sampling point. By means of the selected spacing of the sampling points from one another it is ensured that: in principle, the maximum and minimum values of the high-frequency interference signal are detected and the measurement error is thereby further reduced.

According to a preferred embodiment of the invention, the fifth sampling point is set for the entire period of the high-frequency interference signal before or after the third or fourth sampling point. The sampling frequency in this measuring period is thereby increased, and the measuring error is further reduced by the advantageous positioning of the fifth sampling point.

Particularly preferably, the frequencies of the interference signals are determined beforehand so that these interference signals are known and can be used for the execution of the method.

The device according to the invention having the features of claim 8 is characterized by a control device which is specially prepared for carrying out the method according to the invention in normal use. In this way, the advantages already mentioned are achieved.

The electrical system according to the invention, in particular an on-board electrical system or a traction electrical system of a motor vehicle, having the features of claim 9 is characterized by the device according to the invention. The mentioned advantages are obtained.

Drawings

Further advantages and preferred features and combinations of features result from the preceding description and from the claims. In the following, the invention shall be further elucidated on the basis of the drawing. For this purpose, the sole figure shows a diagram illustrating an advantageous method for operating an analog-to-digital conversion.

Detailed Description

The single figure shows, in a simplified diagram, an exemplary progression of two interference signals S1, S2, which have different frequencies and are superimposed on the useful signal.

The starting points are as follows: the interference signals S1 and S2 are superimposed on a useful signal, for example, a voltage signal of an energy store of a motor vehicle, and together with this useful signal form the input signal to be sampled. For simplicity, in this figure, the interfering signals S1 and S2 are drawn overlappingly. The interference signals S1 and S2 are provided as periodic, in the present case sinusoidal signals, in particular as periodic, in the present case sinusoidal signals which are continuous in time and of known frequency. For this purpose, the interference signals S1 and S2 are detected or calculated in the system beforehand, for example. In the present case, the jamming signal S1 has a frequency of 33 Hz and the jamming signal S2 has a frequency of 100 Hz. Here, the interference amplitudes are 240mV and the effective signal is 3.7V, respectively.

For analog-to-digital conversion, the input signal is sampled, with a maximum of four sampling points being available within a measurement window or measurement period. Here, one measurement period spans 100ms in the present case, alternatively 80 ms. Equidistant sampling points are used so far, only four equidistant sampling points being used in the case of a measurement period of 80ms, as characterized by the five horizontal first lines l _1 to l _5 in the case of a measurement period of 100ms, however it has been shown that: this results in comparatively large measurement errors during the evaluation or during the analog-to-digital conversion. By simply increasing the number of sampling points, it is possible to reduce the measurement error in each case, but this is only possible under certain conditions, which are predetermined by the processing system. Thus, for example, in the traction network of a motor vehicle, it is not possible to detect more than five sampling points in the time interval of 100ms mentioned or to detect more than four sampling points in a shorter time interval of 80ms of the measuring period.

In order to still reduce the measurement error, the advantageous method provides for: these sampling points are determined according to the frequencies of the interference signals S1 and S2. Here, the first sampling point a1 and the second sampling point a2 are predetermined according to the low frequency interference signal S1. The spacing of the sampling points a1 and a2 from each other is selected according to the period duration or frequency of the interference signal S1 so that the spacing is half and at least one full period. This can be described as follows:

x₁= 1/2iT₁+ niT₁，

wherein x₁Is the interval between sample points A1 and A2, T₁Is the period duration of the glitch S1 and n is an integer (0, 1, 2, 3, 4, …). This results in: for example, when the sampling point a1 is at the minimum of the interfering signal S1 as shown in the figure, the second sampling point a2 is at a maximum.

The remaining two sampling points A3 and a4 of the preferably four total sampling points are specified as a function of the high-frequency interference signal S2 and as a function of the position of the sampling points a1 and a 2:

the third sampling point A3 is temporally located before or after (in the figure, before) the first sampling point a1, i.e. spaced apart by the half-cycle duration T of the high-frequency interfering signal S2₂. Thus, the sampling points A3 and a4 are separated from each other by one full period of the interference signal S2, so that the sampling points A3 and a4 are each at the minimum of the interference signal S2, as shown in the drawing, for example.

The fourth sample point A4 is placed half the period duration T before the second sample point A2 for the jammer signal S2₂. Thus, the fourth sample point A4 is spaced apart from the sample point A3 by half and more of a full period duration T₂So that the fourth sample point is at a maximum when sample point a3 is at the minimum of interfering signal 2. The interval x₂Can be described as follows:

x₂= 1/2T₂+ nT₂，

wherein x₂Is the interval, T, between the sampling points A3 and A4 of the second interference signal S2₂Is the period duration of the second interfering signal S2 and n is an integer (0, 1, 2, 3,4，5，…）。

optionally, a fifth sampling point a5 is set, which is set at one period duration T before or after the third or fourth sampling point of the second interference signal S2₂In the present embodiment, the front. Preferably, five sampling points are set in the case where the measurement period is 100ms and only four sampling points are set in the case where the measurement period is 80 ms.

It has been shown that: this can significantly reduce the measurement error when sampling the interference signals S1, S2. Thus, for example, the measurement error of the low-frequency signal S1 can be reduced by 13mV and the measurement error of the high-frequency interference signal S2 can be reduced by 192 mV. Thereby, a more accurate and more reliable analog-to-digital conversion of the input signal is obtained.

The method is especially performed in or by a battery cell controller which monitors the charging voltage of the battery cells. Thereby, a particularly accurate detection of the charging voltage of the battery cell is possible. However, the method may also be used in any other application of analog-to-digital conversion.

List of reference numerals

S1 interference signal

S2 interference signal

l _1 line

l _2 line

l _3 line

l _4 line

l _5 line

Sample point A1

Sample point A2

Sample point A3

Sample point A4

Sample points a 5.