Method for correcting offsets in a control unit of a motor vehicle, and corresponding control unit

Abstract

The invention relates to a method for correcting offsets in a control unit of a motor vehicle. The method comprises a) determining an offset characteristic curve (100) of a measurement channel (130) designed for measuring a parameter (101), comprising the following steps: reading a first support point value (110) of the parameter (101), which is assigned to a first predefined temperature (111), from a dataset; reading a second support point value (112) of the parameter (101), which is assigned to a second predefined temperature (113), from the dataset, the second predefined temperature (113) being lower than the first predefined temperature (111); reading a third support point value (114) of the parameter (101), which is assigned to a third predefined temperature (115), from the dataset, the third predefined temperature (115) being higher than the first predefined temperature (111); and interpolating between the support point values (110, 112, 114) in order to obtain the offset characteristic curve (100). The method also comprises b) adjusting the offset characteristic curve (100), comprising the following steps: receiving an adjustment value (120) of the parameter (101) and an associated adjustment temperature (121); determining a deviation of the adjustment value (120) from the offset characteristic curve (100); adjusting at least one of the support point values (110, 112, 114) based on the deviation; and adjusting the offset characteristic curve (100) based on the at least one adjusted support point value (110, 112, 114). The invention also relates to a corresponding control unit.

Description

[0001] DESCRIPTION

[0002] DESIGNATION

[0003] Method for offset correction in a control unit of a motor vehicle and corresponding control unit

[0004] TECHNICAL FIELD

[0005] The present disclosure relates to control units of motor vehicles and methods implemented thereon. Specifically, it relates to a method for offset correction of a parameter determined by a control unit of a motor vehicle and a corresponding control unit.

[0006] BACKGROUND OF THE INVENTION

[0007] The precise determination of various parameters by control units in a motor vehicle is crucial for the operation and safety of motor vehicles. For example, in electric vehicles and hybrid electric vehicles, battery current is a fundamental signal for the optimal operation of the vehicle and its battery. For this reason, it is important to be able to achieve high precision in measuring the current flow into and out of the battery.

[0008] At the same time, requirements for the accuracy and integrity of a measurement signal should be met across the entire spectrum of possible operating conditions, for example, at all intended operating temperatures. Furthermore, measurement deviations should remain within a specified range across the entire measuring range. It is possible that such measurement deviations may change over the lifetime of a control unit and corresponding measurement sensors, requiring dynamic adjustment of any measurement corrections during operation. SUMMARY AND EMBODIMENTS

[0009] It is therefore an object of the present disclosure to enable accurate, reliable and dynamically adaptable error correction when determining a parameter in a control unit of a motor vehicle.

[0010] This object is achieved by a method for offset correction and a control device according to the independent patent claims. Advantageous embodiments and further developments emerge from the respective dependent claims, the following description, and the drawings.

[0011] Thus, according to a first aspect, a method for offset correction in a control unit of a motor vehicle is provided. The method comprises a) determining an offset characteristic curve of a measuring channel configured for measuring a parameter, comprising the following steps: reading out a first interpolation point value of the parameter, which is assigned to a first predetermined temperature, from a data set; reading out a second interpolation point value of the parameter, which is assigned to a second predetermined temperature, from the data set, wherein the second predetermined temperature is lower than the first predetermined temperature; reading out a third interpolation point value of the parameter, which is assigned to a third predetermined temperature, from the data set, wherein the third predetermined temperature is higher than the first predetermined temperature; and interpolating between the interpolation point values ​​to obtain the offset characteristic curve.The method further comprises b) adjusting the offset characteristic curve, comprising the following steps: receiving, in particular by the control unit, an adjustment value of the parameter and an associated adjustment temperature; determining a deviation of the adjustment value from the offset characteristic curve; adjusting at least one of the reference point values ​​based on the deviation; and adjusting the offset characteristic curve based on the at least one adjusted reference point value. According to a further aspect, a control unit for a motor vehicle is provided, wherein the control unit is configured to carry out the method described above.

[0012] In the context of the present disclosure, an "offset" can mean a control deviation or an offset in the determination of a parameter. The offset can refer to a zero-point deviation. It can be independent of the determined or measured parameter value, particularly at a constant temperature. The offset can be temperature-dependent. The offset can be influenced by systematic deviations in components and / or lines, for example, in the measuring channel.

[0013] In the context of the present disclosure, an "offset characteristic curve" can mean a plurality of temperature-dependent offset values ​​that define a temperature-dependent offset or offset error of the parameter. The temperature-dependent offset values ​​can be distributed continuously or discretely over a predetermined temperature range. In one embodiment, offset correction requires adding the associated offset value to a determined or measured parameter value or subtracting the associated offset value from it, for example, depending on how the offset characteristic curve is defined.

[0014] In the context of the present disclosure, a "parameter" can be an operating parameter, i.e., a variable characteristic of the operation of the control unit and / or the motor vehicle. The parameter is, for example, a voltage or a current, in particular a voltage correlated with a battery current of the motor vehicle.

[0015] According to one embodiment, a "measuring channel" is characterized by an associated measuring range of the parameter. The measuring range can cover the entire parameter range required for the operation of the control unit or only a part of it. In one embodiment, the control unit belongs to a drive system of the motor vehicle. In particular, it is a battery management system. In the context of the present disclosure, in one embodiment, a "data record" is stored in a memory of the control unit and / or in a memory outside the control unit, for example, a central control device of the motor vehicle. The data record can be stored in a lookup table. In addition to the respective reference point values, the associated predetermined temperatures can also be stored in the data record.

[0016] In a practical embodiment, a "base point" or a base point refers to a temperature-related offset value of the parameter, which defines the course of the offset characteristic curve. The base point can, but does not have to, lie on the offset characteristic curve.

[0017] The reference point has a "reference point value" and an associated "specified temperature" as coordinates. The reference point value is preferably an offset value of the parameter. The specified temperature can, for example, be a temperature of the control unit, the measuring channel, a measuring device, and / or an area where the reference point value is measured, particularly after production and before commissioning of the control unit.

[0018] In the context of the present disclosure, "interpolation" means, in particular, determining one or more intermediate offset values ​​between the respective interpolation points. Interpolation can be performed by a linear connection between the respective interpolation points. The linear connection can be extended beyond the smallest specified temperature and / or the largest specified temperature. However, interpolation can also be performed by any other method, in particular by non-linear interpolation, for example an n-th degree interpolation polynomial or trigonometric interpolation. The interpolation points can, but do not have to, lie on the interpolated offset characteristic curve. The adjustment of the offset characteristic curve based on the at least one adjusted interpolation point value can be performed by interpolating between the interpolation point values, taking the adjusted interpolation point value into account.

[0019] In the context of the present disclosure, an "adaptation point" of the parameter refers, in particular, to a temperature-related adaptation value of the parameter, which is determined or measured in order to adjust or correct the offset characteristic curve if necessary. In an expedient embodiment, such an adaptation point is determined under predetermined operating conditions, for example, during startup of the control unit and / or during shutdown of the control unit.

[0020] The adjustment point has as coordinates an "adjustment value" of the parameter and an associated "adjustment temperature." The associated adjustment temperature is, for example, a temperature of the control unit, the measuring channel, a measuring device, and / or an area where the reference point value is measured. The adjustment value and / or the associated adjustment temperature are, for example, sent by a respective measuring device and received by the control unit. The adjustment value can be representative of a measurement signal of the parameter. The adjustment value can be an offset value at the associated adjustment temperature.

[0021] In one embodiment, "determining a deviation of the adjustment value from the offset characteristic curve" comprises determining a difference between the adjustment value and the corresponding value of the offset characteristic curve at the adjustment temperature. Additionally or alternatively, a shortest distance between the adjustment point and the offset characteristic curve can be determined. In a further development, a plurality of deviations from a plurality of adjustment values ​​are determined, and the adjustment of the at least one reference value is carried out based on the plurality of deviations.

[0022] In one embodiment, the "adjustment of a support point value" is achieved by increasing or decreasing the support point value based on a determined deviation from the offset characteristic curve. The adjustment can be performed in such a way that the offset characteristic curve is corrected in the direction of the adjustment points. Partial, complete, or even overcompensation can occur. When adjusting the support point value, the associated preset temperature can, but does not have to, remain unchanged. If the associated preset temperature is also adjusted, this can also be written to the data set.

[0023] According to one embodiment, such a method and such a control unit make it possible to determine a particularly precise and / or particularly reliable parameter value based on the offset correction. By defining the support points in combination with interpolation, the offset characteristic curve can be defined in a particularly simple and efficient manner. Adjusting the support points allows the offset correction to be adapted to changing operating conditions, for example, due to component aging or wear. Such an offset correction method requires little memory space and computing power. Accordingly, the offset correction and the adjustment of the offset characteristic curve can be carried out online and during operation of the control unit and / or the motor vehicle without great effort.

[0024] According to one embodiment, the method further comprises writing the at least one adjusted interpolation point value into the data set, in particular into a data field of the data set associated with the interpolation point value.

[0025] According to one embodiment, the method further comprises: c) offset-correcting an operating value of the parameter, comprising the following steps: receiving, in particular by the control unit, the operating value and an associated operating temperature; and correcting the operating value based on the offset characteristic curve.

[0026] In the context of the present disclosure, an "operating point" may refer to a temperature-related value of the parameter that is determined or measured during operation of the control unit and / or the motor vehicle. The operating point may be characterized by the "operating value" of the parameter and the "associated operating temperature." The associated operating temperature is, for example, a temperature of the control unit, the measuring channel, a measuring device, and / or an area where the operating value is measured.

[0027] Such an embodiment may be advantageous in order to enable a more precise determination or measurement of the parameter during operation by means of an offset correction.

[0028] According to one embodiment, the offset correction is performed continuously during normal operation of the vehicle.

[0029] According to one embodiment, correcting the operating value comprises adding the value of the offset characteristic curve at the operating temperature to the operating value or subtracting the value of the offset characteristic curve at the operating temperature from the operating value. Other correction methods based on comparing the operating point with the offset characteristic curve are also possible.

[0030] According to one embodiment, the parameter is a voltage or a current. Such an embodiment can be advantageous because currents and voltages are fundamental signals, particularly in electric vehicles and hybrid electric vehicles, for enabling reliable and safe operation and for optimizing operation.

[0031] According to one embodiment, the parameter is a voltage, and the method further comprises: d) determining a current, in particular a battery current of a battery of the motor vehicle, from the corrected operating value of the parameter. The voltage can be measured across a resistor, in particular a shunt or current measuring resistor. The current can be determined from a voltage drop across the resistor. In this case, the offset can be defined as a voltage present at OA current flow. According to one embodiment, a battery current of a high-voltage battery for a plug-in hybrid electric vehicle (PHEV) or a battery electric vehicle (BEV), in particular a 400V or 800V battery, is determined.

[0032] According to one embodiment, the control unit is a battery management system (BMS) or the battery management system comprises the control unit.

[0033] According to one embodiment, the received adaptation value is representative of a value of the parameter measured during startup or shutdown of a battery management system of the battery and / or the received adaptation value is representative of a value of the parameter that is measured when an electrical connection between the measuring channel and the battery is interrupted. In one development, the electrical connection is interrupted because an intermediate switch, for example a contactor, is open. Startup and / or shutdown of the battery management system can be associated with closing or opening such a switch. When the switch is open, the current flow through the measuring channel can be zero. As a result, a corresponding adaptation value can be directly determined at the adaptation temperature. The adaptation temperature preferably corresponds to a temperature during startup or shutdown.Shutdown of the battery management system. In a further development, the measured adjustment value is received by the control unit, in particular to adjust the offset characteristic curve.

[0034] Such an embodiment can be advantageous for determining an offset that takes into account various or even all characteristics of the measurement channel, for example, characteristics of the conductor tracks or the components of the measurement channel. Such comprehensive consideration can be difficult or even impossible as soon as a current flows through the measurement channel, which changes the properties of the conductor tracks and / or components.

[0035] According to one embodiment, the received adjustment value is representative of a parameter value measured when no external influences act on the measurement channel. In particular, the system can be without load, so that the channel's noise or error is measured at the current temperature. In a battery management system, for example, the HV contactors can be open and the HV battery not yet connected.

[0036] According to a further embodiment, at least one additional support point value is determined at an associated predetermined temperature, and the at least one additional support point value is taken into account during interpolation to obtain the offset characteristic curve. For example, one, two, three, four, five, more than five, or more than ten additional support point values ​​are determined and taken into account.

[0037] Such an embodiment can be advantageous because additional interpolation point values ​​increase the accuracy of the offset correction, in particular when an offset drift of the measuring channel has a non-linear course.

[0038] According to a further embodiment, the first reference point value is not adjusted. For example, the first reference point value can be measured more precisely than the other reference point values. The first predetermined temperature can expediently lie within a preferred temperature range for which the control unit, in particular the measuring channel, is designed or optimized. This preferred temperature range includes, for example, room temperature, for example, 25°C. In this respect, a possible drift can also be smaller than in other temperature ranges, and consequently, an adjustment of the first reference point value can be dispensed with. In an alternative embodiment, the first reference point value is adjustable.

[0039] According to one embodiment, after production of the control unit and before commissioning of the motor vehicle having the control unit, the first reference point value is measured and the second and third reference point values ​​are set equal to the first reference point value or the second and third reference point values ​​are set equal to simulated and / or calculated values, wherein in particular the reference point values ​​are written into the data set, for example into the associated data fields of the data set. The first reference point value can be set equal to zero through calibration. The offset of the measuring channel and / or the offset of other measuring channels can be zero or close to zero at the first predetermined temperature, in particular after production and before commissioning. Production can include commissioning for test purposes.

[0040] Such an embodiment can be advantageous for establishing a suitable starting point for adjusting the offset during operation. Due to the expected temperature variation after commissioning, it may be advantageous to adjust the second, third, and possibly additional reference point values ​​only after commissioning. It may also be advantageous that only one measurement—i.e., the measurement of the first reference point, e.g., at ambient temperature—is required as a starting point.

[0041] According to a further embodiment, the first predetermined temperature is a room temperature or ambient temperature, and / or the second predetermined temperature is determined by a lower operating temperature limit, in particular -40°C, and / or the third predetermined temperature is determined by an upper operating temperature limit, in particular 120°C. The operating temperature limits can be determined by the hardware of the control unit and / or by legal requirements. Such an embodiment can be advantageous for enabling efficient offset correction across the entire range of possible operating temperatures. Measurement at ambient temperature can be particularly accurate.

[0042] According to a further embodiment, the method further comprises: determining a further offset characteristic curve of a further measuring channel set up for measuring the parameter; and adjusting the further offset characteristic curve. The determination of the further offset characteristic curve of the further measuring channel and the adjustment of the further offset characteristic curve can be carried out analogously to the methods previously described for the measuring channel. In a further development, offset characteristics for three, four, five, more than five, or more than ten measuring channels are determined and adjusted in this way. With the above embodiment, an offset correction of different measuring channels can therefore be carried out and coordinated with one another. Independent measurements, for example of a current, can be used for plausibility checks in order to meet safety requirements for the system and / or to achieve greater accuracy.

[0043] According to a further embodiment, the additional measuring channel is a redundant measuring channel and / or the additional measuring channel has a smaller or larger measuring range than the measuring channel. A further measuring channel with a smaller measuring range can have greater accuracy than the measuring channel. A further measuring channel with a larger measuring range can have lower accuracy than the measuring channel. Measuring channels with different measuring ranges can be advantageous for achieving greater accuracy for certain measured values, for example, measured values ​​under typical operating conditions.

[0044] A redundant measurement channel can have the same measurement range as the measurement channel, but can also have a smaller or larger measurement range. Such a redundant measurement channel can be advantageous for calibration with the measurement channel. For example, in a current measurement, one measurement channel can be designed to measure from -50A to 50A, and the other measurement channel can be designed to measure from -500A to +500A.

[0045] According to a further embodiment, the method further comprises a plausibility check of the measurement channel, taking into account the further measurement channel, based on the offset characteristic curve and the further offset characteristic curve. Such an embodiment can increase the accuracy and / or reliability of measurements of the parameter, in particular due to the continuous adjustment of the offset characteristic curve and the further offset characteristic curve.

[0046] In the context of the present disclosure, the term "plausibility check" specifically means providing additional reasons and / or facts to increase the accuracy and / or reliability of a measured parameter value. For this purpose, measurements of the parameter can be compared across different measurement channels.

[0047] According to a further embodiment, the method further comprises detecting an error in the measuring channel based on the deviation of the adjustment value from the offset characteristic curve, in particular if the at least one reference point value must be adjusted too frequently or too significantly, for example, compared to a proper measuring channel, and / or if different measuring channels deviate too significantly from one another, for example, more significantly than in a proper control unit. The error can, for example, relate to a malfunction in a component and / or an electrical line of the measuring channel.

[0048] BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Further advantages and advantageous embodiments and further developments of the method and of the control device emerge from the following exemplary embodiments shown in conjunction with the figures.

[0050] They show:

[0051] Figure 1 shows a method for offset correction in a current measurement according to an embodiment of the present disclosure and

[0052] Figures 2 to 4 each show offsets of different measurement channels and an offset characteristic curve according to an embodiment of the present disclosure.

[0053] Identical, similar, or functionally identical elements are provided with the same reference symbols in the figures. In some figures, individual reference symbols have been omitted for clarity. The figures and the relative sizes of the elements depicted in the figures are not to scale. Rather, individual elements may be exaggerated for clarity and / or clarity.

[0054] DETAILED DESCRIPTION OF EMBODIMENTS

[0055] Figure 1 shows a method for offset correction of a parameter determined by a motor vehicle control unit, in this case a voltage measured across a shunt resistor 141. In battery management systems, the battery current is usually determined using such a shunt-based measurement. The current generates a voltage drop across the shunt 141. When the voltage is measured via corresponding amplifiers, in this case a full-range amplifier 130, a low-range amplifier 132, and a redundant full-range amplifier 134, with one or more analog-to-digital converters (ADCs) 142, this correlates with the current value. The different amplifiers are assigned to corresponding measurement channels 130, 132, and 134.

[0056] The measurement must meet the vehicle's technical requirements, such as a temperature range of -40°C to 120°C, a current measuring range of -300 to 1000A, etc. In addition, from a safety perspective, there are high demands on the accuracy and integrity of the current signal. The integrity of the signal can be ensured by redundant measurement using a redundant measuring channel 134. The high accuracy requirements are met, similar to a multimeter, by different measuring ranges with their own measuring channels 130, 132, 134. Low currents, such as -100 to 200A, are measured using a measuring channel 132 that is designed for this range. A second measuring channel 130 covers, for example, the full range from -300 to 1000A. This ensures that the measurement error in the low range does not become too great.

[0057] Thus, there are several hardware-implemented measurement channels 130, 132, and 134 that tap the voltage signal from shunt 141. This results in the problem that each measurement channel 130, 132, and 134 exhibits its own drift over its lifetime and also temperature variation during operation, due to the respective hardware circuitry, components, and position on the board. This primarily affects the current measurement offset, i.e., the voltage present at 0 V current flow. This offset error impairs the accuracy of the current measurement and must be corrected. Furthermore, the offset error can negatively impact the plausibility check between channels 130, 132, and 134.

[0058] One possible way to achieve this correction is to perform a full measurement of the behavior to store a correction factor as a map for each measurement channel (130, 132, 134) in the control unit. However, this method requires considerable effort to determine the factor and requires a significant amount of memory, especially if it must be used for multiple measurement channels (130, 132, 134). Under certain circumstances, such a full measurement must be performed for each device produced.

[0059] Based on the output signal of the analog-to-digital converter 142, the current determination 150 may include the following steps: selecting an amplifier range; temperature compensation based on a corresponding offset characteristic, which requires determining 152 the temperature at the shunt 141 or the respective measurement channel 130, 132, 134; and plausibility checks between the primary and redundant current determinations. The current can then be output 151.

[0060] Figures 2 to 4 show temperature-dependent offset errors 131, 133, 135 of various measurement channels as well as a temperature-dependent offset characteristic curve 100. Shown is the offset drift 101 in mV as a function of the temperature 102 in °C. The offset error 131 belongs to a full-range measurement channel, the offset error 133 belongs to a low-range measurement channel, and the offset error 135 belongs to a redundant full-range measurement channel.

[0061] The offset characteristic curve 100 for the offset error 131 of the full-range measuring channel is determined with the following steps: reading out a first interpolation point value 110 of the parameter 101 at a first predetermined temperature 111 from a data set; reading out a second interpolation point value 112 of the parameter 101 at a second predetermined temperature 113 from the data set, wherein the second predetermined temperature 113 is lower than the first predetermined temperature 112; and reading out a third interpolation point value 114 of the parameter 101 at a third predetermined temperature 115 from the data set, wherein the third predetermined temperature 115 is higher than the first predetermined temperature 111; and interpolating between the interpolation point values ​​110, 112, 114 to obtain the offset characteristic curve 100.

[0062] Figure 2 shows the offset characteristic curve 100 of the full-range measurement channel after production and before commissioning (end of line). The first reference point value 110 is measured as an offset in the de-energized state and at a defined first predefined temperature 111 (e.g., 25 °C). The first reference point value 110 is then stored in the control unit, for example, a battery management system.

[0063] The offset drift is stored in the control unit as a characteristic curve versus temperature with at least three interpolation points 110, 112, 114, including a second interpolation point 112 at a second specified temperature 113 in the cold range, here at -40 °C, a third interpolation point 114 at a third specified temperature 115 in the warm range, here at 120 °C, and finally an end-of-line calibration point as a first interpolation point 110 at a first specified temperature 111. Linear interpolation between the interpolation points 110, 112, 114 results in the offset characteristic curve 100, which can be used to determine a temperature-dependent offset. After production (end of line), the interpolation points are all set to an identical value, here to 0 mV. In an alternative embodiment, only the first support point 110 is set to 0 mV and the other support points 112, 114 are set to a respective calculated or simulated offset value.This allows accuracy to be improved already at the end of line and temperature-dependent offset errors can be at least partially compensated.

[0064] Figures 3 and 4 show the adjustment of the offset characteristic curve based on various online measurements, each of which determines an adjustment value 120 at a corresponding adjustment temperature 121. "Online measurements" are performed during operation and / or after commissioning of the control unit. First, a check is performed to determine whether a measurement can be directly assigned to a temperature reference point 110, 112, or 114.The offset characteristic curve 100 is adjusted by adjusting at least one interpolation point value 110, 112, 114, which comprises the following steps: receiving the adjustment value 120 of the parameter 101 and the associated adjustment temperature 121 by the control unit from a measuring device; determining a deviation of the adjustment value 120 from the offset characteristic curve 100; adjusting the at least one interpolation point value 110, 112, 114 based on the deviation, wherein in this case only the two outer interpolation points 112, 114 are adjusted and not the end of line (EOL) adjustment point 110; and writing the at least one adjusted interpolation point value 110, 112, 114 into the associated data field of the data record. In other words, the current offset value 120 of the offset characteristic curve 100 is adapted to the measured temperature 121 by changing the existing support points 110, 112, 114.The offset correction factor is calculated during operation with linear interpolation via temperature between the stored support points 110, 112, 114.

[0065] Figures 2, 3, and 4 illustrate a method for determining and learning the offset correction for individual measurement channels during operation, thus achieving particularly high accuracy and low deviation between the measurement channels for current measurement. This is achieved by measuring voltage across a resistor. For each measurement channel, a characteristic curve 100 (correction value vs. temperature) with at least three interpolation points 110, 112, and 114 for the offset is stored in the control unit. During operation, the temperature at the shunt / measurement channel is determined, and the corresponding correction value for the measured current is interpolated from the characteristic curve 100. Essential steps of the procedure for online adaptation of the offset characteristic curve 100 can be measurement of the offset 120 of the respective measuring channel at 0A (start-up or powerdown, contactors open) as well as adaptation of the characteristic curves 100 in the direction of the respective measured values ​​120 by adjusting the existing support points 110, 112, 114.

[0066] The invention is not limited to the exemplary embodiments by the description. Rather, the invention encompasses any novel feature and any combination of features, including, in particular, any combination of features in the exemplary embodiments and patent claims. REFERENCE SIGNS

[0067] 100 offset characteristic curve

[0068] 101 parameters

[0069] 102 Temperature

[0070] 110 first support point value

[0071] 111 first specified temperature

[0072] 112 second support point value

[0073] 113 second preset temperature

[0074] 114 third support point value

[0075] 115 third preset temperature

[0076] 120 Adjustment value

[0077] 121 Adaptation temperature

[0078] 130 measuring channels

[0079] 131 Offset error of the measuring channel

[0080] 132 additional measuring channels

[0081] 133 Offset error of the additional measuring channel

[0082] 134 redundant measuring channels

[0083] 135 Offset error of the redundant measuring channel

[0084] 140 control unit

[0085] 141 Shunt resistance

[0086] 142 analog-to-digital converters

[0087] 150 Determining the parameter

[0088] 151 Outputting the parameter

[0089] 152 Determining the temperature

Claims

PATENT CLAIMS 1 . Method for offset correction in a control unit of a motor vehicle, the method comprising a) determining an offset characteristic curve (100) of a measuring channel (130) set up for measuring a parameter (101), comprising the following steps: Reading out a first support point value (110) of the parameter (101) associated with a first predetermined temperature (111) from a data set; Reading out a second support point value (112) of the parameter (101) associated with a second predetermined temperature (113) from the data set, wherein the second predetermined temperature (113) is lower than the first predetermined temperature (111); Reading out a third support point value (114) of the parameter (101) associated with a third predetermined temperature (115) from the data set, wherein the third predetermined temperature (115) is greater than the first predetermined temperature (111); and Interpolating between the interpolation point values ​​(110, 112, 114) to obtain the offset characteristic curve (100); b) adjusting the offset characteristic curve (100), comprising the following steps: Receiving an adjustment value (120) of the parameter (101) and an associated adjustment temperature (121); Determining a deviation of the adjustment value (120) from the offset characteristic curve (100); Adjusting at least one of the support point values ​​(110, 112, 114) based on the deviation; and Adjusting the offset characteristic curve (100) based on the at least one adjusted support point value (110, 112, 114).

2. Method according to the preceding claim, further comprising c) offset-correcting an operating value of the parameter (101), comprising the following steps Receiving the operating value and an associated operating temperature; and Correcting the operating value based on the offset characteristic (100).

3. Method according to the preceding claim, wherein correcting the operating value comprises adding the value of the offset characteristic curve (100) at the operating temperature to the operating value or subtracting the value of the offset characteristic curve (100) at the operating temperature from the operating value.

4. Method according to one of the preceding claims, wherein the parameter (101) is a voltage or a current.

5. Method according to one of claims 2 or 3, wherein the parameter (101 ) is a voltage, the method further comprising d) determining a current intensity, in particular a battery current intensity of a battery of the motor vehicle, from the corrected operating value of the parameter (101 ).

6. The method according to the preceding claim, wherein the received adaptation value (120) is representative of a value of the parameter measured during startup or shutdown of a battery management system of the battery and / or is representative of a value of the parameter measured when an electrical connection between the measuring channel (130) and the battery is interrupted.

7. Method according to one of the preceding claims, wherein at least one further support point value is determined at an associated predetermined temperature and the at least one further support point value is taken into account during interpolation in order to obtain the offset characteristic curve (100).

8. Method according to one of the preceding claims, wherein the first support point value (110) is not adjusted.

9. Method according to the preceding claim, wherein after manufacture of the control unit and before commissioning of the motor vehicle having the control unit, the first support point value (110) is measured and the second and the third support point value (112, 114) are set equal to the first support point value (110) or the second and the third support point value (112, 114) are set equal to simulated and / or calculated values.

10. The method according to one of the preceding claims, wherein the first predetermined temperature (111) is a room temperature and / or the second predetermined temperature (113) is determined by a lower operating temperature limit, in particular -40 °C, and / or the third predetermined temperature (115) is determined by an upper operating temperature limit, in particular 120 °C. 11 . Method according to one of the preceding claims, further comprising determining a further offset characteristic of a signal used for a measurement of the Parameter (101) set up further measuring channel (132, 134); and adjusting the further offset characteristic curve.

12. Method according to the preceding claim, wherein the further measuring channel (132, 134) is a redundant measuring channel (134) and / or has a smaller or larger measuring range than the measuring channel (130).

13. Method according to one of claims 11 or 12, further comprising checking the plausibility of the measuring channel (130) taking into account the further Measuring channel (132, 134) based on the offset characteristic curve (100) and the further offset characteristic curve.

14. The method according to any one of the preceding claims, further comprising detecting an error in the measuring channel (130) based on the Deviation of the adjustment value (120) from the offset characteristic curve (100).

15. Control unit for a motor vehicle, wherein the control unit is configured to carry out a method according to one of the preceding claims.

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