WO2014063915A1

WO2014063915A1 - Method for testing external measuring units

Info

Publication number: WO2014063915A1
Application number: PCT/EP2013/070761
Authority: WO
Inventors: Jochen Weber; Andreas Heyl
Original assignee: Robert Bosch Gmbh; Samsung Sdi Co., Ltd.
Priority date: 2012-10-24
Filing date: 2013-10-07
Publication date: 2014-05-01
Also published as: DE102012219377A1

Abstract

The invention relates to a method for testing external measuring units (12, 14, 16), wherein the at least one measuring unit (12, 14, 16) is connected to a control device (10) and each measuring unit (12, 14, 16) comprises an analogue/digital converter (22). The method is characterized in that a signal generator (24) is associated with each measuring unit (12, 14, 16) and the following method steps are performed once or periodically for the at least one measuring unit (12, 14, 16): a) provision of an analogue test signal by the signal generator (24); b) retrieval of a measurement value from the measuring unit (12, 14, 16) by the control device (10), wherein the analogue test signal is converted into a digital measurement value by the measuring unit (12, 14, 16) and transmitted to the control device (10); c) comparison of the received digitized measurement value to a stored reference value in the control device (10); and d) initiation of a fault response (130) in the event that deviations are determined during the comparison.

Description

Description title

The invention relates to a method for testing external measuring units, wherein at least one measuring unit is connected to a control unit and each measuring unit is connected to a control unit

Analog / digital converter includes. Furthermore, the invention relates to a device for carrying out the method. In many applications, external sensors connected to a controller are used to collect data about the environment, data about the state of technical devices, and user input. In this case, the sensor is located with an analog / digital converter outside the controller and is connected to this example via a bus (for example, CAN, SPI).

An exemplary application is the battery management system for high-voltage batteries such as those used in electric vehicles. Here are several

Battery modules distributed in the vehicle, each battery module includes a measuring chip with analog / digital converter and a multiplexer. With the multiplexer, the

Analog / digital converters are connected to one of a plurality of signal inputs, wherein at the inputs sensors for example voltage or temperature are connected. The measured data are sent to a central control unit, the battery management system. For the battery management system to perform its safety function, it must be ensured that the measurement data are correct.

From DE 10 2010 030 818 A1 a device for improving the accuracy of battery monitoring parts is known. In this case, several monitors are connected to a central control. Each monitor has a number of channels that can be used to measure battery cell characteristics. To compensate for measurement deviations between the various supervisors is provided that a

Measuring channel is measured by two adjacent monitors together. As a result, one and the same measurand is measured with two different monitors and at Deviations, a correction factor is calculated. Using this correction factor, readings are modified by the supervisor or central control so that all monitors provide the same reading for the same input. A disadvantage of the prior art is that for testing the analog / digital converter no reference signal can be specified in order to test a correct conversion of a measurement signal over the entire range of values. Furthermore, with solutions from the prior art, it has hitherto not been possible to unambiguously associate the received measured value with a specific external measuring unit connected to the bus in order to rule out errors in the data transmission via the common bus.

Disclosure of the invention

It is proposed a method for testing external measuring units, wherein at least one measuring unit is connected to a control unit and each measuring unit one

Analog / digital converter comprises, wherein each measuring unit is associated with a signal generator and the following method steps once or periodically for the at least one

Be passed through the measuring unit: a) providing an analog test signal by the signal generator,

b) retrieving a measured value from the measuring unit by the control unit, wherein the analog test signal is converted into a digital measured value by the measuring unit and sent to the control unit,

c) comparing the received digitized measured value with a stored reference value in the control unit and

d) initiating an error reaction if deviations are found during the comparison

become.

An external measuring unit is for example a measuring chip with several analogue

Inputs, where the analog signals applied to the inputs of a

Analog / digital converters are digitized. The measuring chip is connected to a control unit, which processes its measured values. Several possible errors are conceivable. For example, it is possible that the characteristics or the used

Reference voltage of the analog / digital converter are falsified, resulting in the analog / digital conversion to false digital readings. Furthermore, it is possible that the Switching between different analog inputs does not work properly, so the analog to digital converter processes a wrong input signal. Furthermore, it is possible that an error occurs in the connection between the external measuring unit and the control unit, so that, for example, outdated data is transmitted or another measuring chip is addressed by the control unit.

In order to detect these errors, an analog test signal known to the control unit is generated by a signal generator assigned to the measuring unit. The output of the signal generator is connected to an input of the external measuring unit, so that the analog test signal can be converted by means of the analog / digital converter into a digital measured value, which is sent to the control unit. The analog test signal can already be specified in one embodiment during the production of the external measuring unit. If, for example, the characteristic curve or the reference voltage of the analog / digital converter is corrupted, the digitized measured value deviates from the measured value stored in the control unit. If the comparison made in the control unit

Deviations are detected, an error reaction can be initiated. This can be that the control unit is switched off or the

Whole system is put into a safe operating state.

In one embodiment of the method, the analog test signal is not already specified during the production of the external measuring unit, but can be set as desired by the control unit. For this purpose, in step a) of the method, the signal generator assigned to the measuring unit is controlled by the control unit.

In a preferred embodiment of the method, the analog test signal has a time-constant signal level, which is predetermined by the control unit, wherein the method steps a) to c) are run at least twice for each different signal level.

By repeating the test with several signal levels, it can be ensured that actually when retrieving a measured value in accordance with step b) a current measured value is converted and sent to the control unit. In addition, tests at different Signal levels performed so that deviations in the characteristic or the reference voltage of the analog / digital converter can be detected more easily and reliably.

In a further preferred embodiment, the analog test signal has a time varying between an upper and a lower level signal level, wherein the upper and lower levels are optionally specified by the controller and wherein the method steps b) and c) are repeated, each one Receive measured value of the upper and one of the lower level and to compare each with a stored reference value.

Here, in one variant, the test signal can be generated by an implemented in hardware oscillator as a signal generator with a fixed upper and lower signal level without further control. In another variant, the signal generator is controlled by the control unit, wherein the upper and the lower level are specified by this.

In both variants, the method steps b) and c) are repeated, so that both the upper and the lower level were measured at least once. Again, the use of multiple signal levels facilitates the detection of distortions of the characteristic and / or the reference voltage of the analog / digital converter.

In one embodiment of the method, the at least one measuring unit is a

The monitoring unit for a battery module and a used level of the analog test signal corresponds to a lower threshold of the battery voltage and another used level of the analog test signal corresponds to an upper threshold of the battery

Battery voltage.

This choice of signal levels used for testing, in the case of

Using a measuring unit as a monitoring unit for a battery module, the critical value ranges of the signals to be monitored are particularly well covered. In the case of the battery, for example, the voltages of individual cells are monitored for overshoots of undervoltage and overvoltage thresholds. It is therefore important to ensure the characteristic of the analog / digital converter in this area particularly well.

In a further embodiment of the method, a plurality of measuring units are connected to the control unit, each measuring unit being an individual analogue test signal is assigned and for each measuring unit a corresponding individual reference value is stored in the control unit.

As a result of this measure, the control unit can distinguish the individual measuring units from one another, since each received digital measured value can be unambiguously assigned to one measuring unit. In this way, errors in the connection of the measuring unit with the control unit can reveal in which a wrong measuring unit responds to a request from the controller. In one embodiment of the method, the measuring units to be tested comprise a multiplexer, via which the analog / digital converter can be connected to one of a plurality of signal inputs, the output of which is assigned to the measuring unit

Signal generator is connected to a signal input of the multiplexer, and in the conversion according to step b) of the method, this signal input is connected through the multiplexer to the analog / digital converter.

The proposed method can also detect a malfunction of the multiplexer in which the multiplexer no longer switches correctly between the inputs. If the multiplexer does not switch to the input connected to the signal generator as expected, the expected test signal will not be measured.

In one embodiment of the method, the at least one measuring unit and the control unit communicate with each other via a bus, with the driving of the signal generator assigned to a measuring unit also being effected via the bus. The bus can

be executed for example as CAN or SPI.

In this way, addressing errors can be detected on the bus, in which the control of the signal generator, a different measuring chip reacts as when retrieving a measured value.

Another aspect of the invention is a device for testing external

To provide measuring units, wherein one or more measuring units with a

Control unit are connected and each measuring unit comprises an analog / digital converter, and wherein each measuring unit is associated with a signal generator and the controller is adapted to carry out the described method. In one embodiment of the device, the at least one measuring unit further comprises a multiplexer via which the analog / digital converter can be connected to one of a plurality of signal inputs, wherein the output of the signal generator associated with the measuring unit is connected to a signal input of the multiplexer.

In a further embodiment, the at least one measuring unit and the

Control unit connected to each other via a bus. In a further embodiment, the at least one measuring unit comprises a

Control output, which is connected to the associated signal generator, wherein the control output can be switched by the controller to control the associated signal generator. The control output is designed, for example, as GIPIO (General Purpose Input / Output).

In a preferred embodiment of the device, the at least one measuring unit is a monitoring unit for a battery module.

Advantages of the invention

The inventive method makes it possible for the signal detection for

High-security safety functions can be secured via a single measuring chip without the need for a redundant signal path in the form of a second measuring chip or another hardware circuit, as defined in ISO standard 26262.

By avoiding a second redundant measuring chip or another redundant hardware circuit, the implementation of the signal acquisition is considerably simplified, whereby components and thus costs are saved.

Advantageously, in the method, the individual measuring units can be clearly identified by the control unit, whereby not only the function of the converter itself, but also the connection of the measuring units can be tested with the control unit. Brief description of the drawings

FIG. 1 shows a schematic representation of a battery management system with a central control unit and distributed via a bus

Battery modules,

FIG. 2 shows the activation of a test signal for an external measuring unit by means of a

Control unit, Figure 3 shows a flowchart of the method. Embodiments of the invention

FIG. 1 shows a battery management system with a central control unit and distributed battery modules connected via a bus, each having a measuring chip and associated one

Signal generator.

The illustration in FIG. 1 shows a device 1 for testing external measuring units 12, 14, 16. The device 1 comprises a control unit 10 with a microcontroller 18. The control unit 10 is connected via a bus 20 to the external measuring units 12, 14, 16. Each of the measuring units 12, 14, 16 comprises a measuring chip with analog-to-digital converter 22 and a signal generator 24 associated with the measuring chip

Analog / digital converter 22, an analog input signal is converted into a digitized measured value.

In the case of a battery management system, the controller 10 is the central

Battery management system and the external measuring units 12, 14, 16 are the individual battery monitoring modules. Each battery module is thereby with a

Battery monitoring module equipped, which measures important parameters such as voltage and temperature and sends to the central battery management system.

To test the measuring chips of the individual external measuring units 12, 14, 16 or of the individual battery monitoring modules, the control unit 10 sends a control command 28 to the signal generator 24 of the external measuring unit 12 to be tested via the bus 20. The signal generator 24 then generates an analog test signal 26. Das analog test signal 26 is connected to an input of analog-to-digital converter 22. In the second step b) of the method, a digitized measured value 30 of the external measuring unit 12 is called up by the control unit 10. By comparing the received digital measured value with a reference value stored in the control unit 10, deviations from the desired behavior of the measuring unit 12 can be determined.

Depending on the embodiment of the method, the steps a) to c) are repeated several times, wherein the signal generator 24 each generates an analog test signal 26 with a different level. As a result, distortions of the characteristic curve or the reference voltage of the analog / digital converter 22 of the measuring chip can be easily detected.

FIG. 2 shows a more detailed schematic representation of an external measuring unit 12.

FIG. 2 shows an external measuring unit 12 which comprises a measuring chip with an analog / digital converter 22, a program logic unit 32 and a multiplexer 34. The multiplexer 34 includes a plurality of signal inputs 36, one of the

Signal inputs connected to one of the external measuring unit 12 associated signal generator 24. The signal generator 24 in turn is connected to a GPIO output 38 (General Purpose Input / Output) of the external measuring unit 12. This GPIO output 38 can be turned on or off by the program logic unit 32.

The external measuring unit 12 is connected via a bus 20 to a control unit 10. The control unit 10 again comprises a microcontroller 18. In order to test the external measuring unit 12, a control signal is transmitted via the bus 20 to the control unit 10 in accordance with step a) of the method by the microcontroller 18 of the control unit 10

Program logic unit 32 of the external measuring unit 12 is sent. The external measuring unit 12 then activates the GPIO output 38 and thus its associated one

Signal generator 24. The signal generator 24 then outputs an analog test signal, which is connected via a connecting line 26 to one of the inputs 36 of the multiplexer 34.

In the second step b) of the method, the control unit 10 calls a measured value from the external measuring unit 12 via the bus 20, wherein the multiplexer 34 is connected to the input which is connected to the signal generator 24. The obtained digital Measured value is in turn sent via the bus 20 to the microcontroller 18 of the control unit 10.

In step c) of the method, the received digitized measured value is compared with a reference value stored in the control unit 10. If deviations are detected, an error reaction is initiated according to step d) of the method. This error response may be, for example, a shutdown of the system or the system being placed in a safe operating state. Depending on the embodiment of the method, the steps a) to c) can be repeated several times, wherein 24 analog test signals with different levels are generated by the signal generator. Depending on the embodiment, it is possible to set the signal level used via the connection of the signal generator 24 to the program logic unit 32 by the control unit.

In a further embodiment, the signal generator 24 begins to generate an analog test signal after its activation which varies in time between an upper and a lower signal level. In this case, the method steps b) and c) are repeated in order to obtain in each case a measured value of the upper and one of the lower level, wherein the digital measured values obtained are each compared with a stored reference value.

In Figure 3, the flow of the process is shown schematically. As can be seen from the illustration in FIG. 3, the method can be run through periodically. In the first step a) of the process, in the diagram with the

Numeral 100, an analog test signal is provided. The test signal is generated by the signal generator to be tested associated signal generator. In the second step b) of the method, denoted by the reference numeral 1 10 in the diagram, a measured value is retrieved by the control unit from the measuring unit to be tested. In this case, the analog test signal is converted into a digital measured value by the measuring unit and sent to the control unit.

In the third step c) of the method, designated by the reference numeral 120, the received digitized measured value is stored with a reference value stored in the control unit compared. If deviations are found during the comparison, an error reaction 133 is initiated according to step d) of the method. Otherwise, the process is again run from the beginning, as indicated by reference numeral 124.

In one embodiment of the method, a plurality of external measuring units are connected to the control unit. In this case, the next unit to be tested is selected via an additional step 140 before the procedure is repeated.

Claims

claims

1 . Method for testing external measuring units (12, 14, 16), wherein the at least one measuring unit (12, 14, 16) is connected to a control unit (10) and each measuring unit (12, 14, 16) comprises an analogue / digital converter ( 22), characterized in that each measuring unit (12, 14, 16) is associated with a signal generator (24) and the following

Process steps are repeated once or periodically for the at least one measuring unit (12, 14, 16):

a) providing an analog test signal by the signal generator (24), b) retrieving a measured value from the measuring unit (12, 14, 16) by the

Control unit (10), wherein the analog test signal is converted into a digital measured value by the measuring unit (12, 14, 16) and sent to the control unit (10),

c) comparing the received digitized measured value with a

stored reference value in the control unit (10) and

d) initiating an error reaction (130) if deviations are detected during the comparison.

2. The method according to claim 1, characterized in that in step a) of the method of the signal generator (24) is controlled by the control unit (10).

3. The method according to claim 2, characterized in that the analog test signal has a time constant signal level, which is predetermined by the control unit (10), wherein the method steps a) to c) are traversed at least twice for each different signal level.

4. The method according to claim 1 or 2, characterized in that the analog

Test signal has a signal level varying in time between an upper and a lower level, wherein the upper and the lower level are optionally given by the control unit (10) and wherein the method steps b) and c) are repeated, in each case a measured value of the upper and lower level and compare each with a stored reference value.

5. The method according to claim 3 or 4, characterized in that the at least one measuring unit (12, 14, 16) is a monitoring unit for a battery module and a used level of the analog test signal corresponds to a lower threshold of the battery voltage and another used level of the analog Test signal corresponds to an upper threshold of the battery voltage.

6. The method according to any one of claims 1 to 5, wherein a plurality of measuring units (12, 14, 16) are connected to the control unit (10), characterized in that each

Measuring unit (12, 14, 16) is assigned an individual analog test signal and for each measuring unit (12, 14, 16), a corresponding individual reference value in the control unit (10) is deposited.

7. The method according to any one of claims 1 to 6, wherein the test unit to be tested (12, 14, 16) comprises a multiplexer (34) via which the analog / digital converter (22) connected to one of a plurality of signal inputs (36) can be, characterized in that the output of the measuring unit (12, 14, 16) associated signal generator (24) with a signal input (36) of the multiplexer (34) is connected, and in the conversion according to step b) of this signal input (36 ) is connected through the multiplexer (34) to the analog-to-digital converter (22).

8. The method according to any one of claims 1 to 7, characterized in that the at least one measuring unit (12, 14, 16) and the control unit (10) communicate with each other via a bus (20), wherein the driving of a measuring unit (12 , 14, 16) associated signal generator via the bus (20).

9. Apparatus (1) for testing external measuring units (12, 14, 16), wherein one or more measuring units (12, 14, 16) are connected to a control unit (10) and each measuring unit (12, 14, 16) an analog / Digital converter (22) thereby

in that each measuring unit (12, 14, 16) is assigned a signal generator (24) and the control unit (10) is designed to carry out the method according to one of Claims 1 to 8.

The apparatus of claim 9, wherein the at least one measuring unit (12, 14, 16) further comprises a multiplexer (34) via which the analog to digital converter (22) can be connected to one of a plurality of signal inputs (36) , characterized in that the output of the signal generator (24) associated with the measuring unit (12, 14, 16) is connected to a signal input (36) of the multiplexer (34).

1 1. Apparatus according to claim 9 or 10, characterized in that the at least one measuring unit (12, 14, 16) and the control unit (10) via a bus (20) are interconnected.

12. The device according to claim 10, characterized in that the at least one measuring unit (12, 14, 16) comprises a control output (38) which is connected to the associated signal generator (24), wherein the control output (38) by the control unit (38). 10) can be switched to control the associated signal generator (24).

13. Device according to one of claims 8 to 11, characterized in that the at least one measuring unit (12, 14, 16) is a monitoring unit for a battery module.