SE538602C2 - Electrical control system and method for functional control of ground connection of electronic control unit of such an electrical control system - Google Patents

Abstract

19 SUMMARY An electrical control system comprises electronic control units (2-5) designed to control electrical equipment and provided with a ground connection (7-10). The units are provided with means (14-17) for measuring the internal voltage between the input side of each unit and the earth connection. The units pass this voltage value on to other units which compare it with a predetermined value and determine that the unit in question has lost ground connection if the difference between the compared voltage values exceeds a predetermined amount. (Fig. 1).

Description

THE FIELD OF THE INVENTION The present invention relates to an electric control system. control of electrical equipment or a monitoring electronic unit, which further unit is connected to a system input side of said first electronic control unit, and a procedure according to the preamble of the appended independent procedural patent claims.

In this case, the electrical control system may comprise a network of control units, for example Controller Area Network = CAN, with a relatively large number of said first electronic control units, for example arranged for controlling equipment in a motor vehicle, but the electrical control system could also have only the first electronic control unit mentioned and a monitoring electronic unit connected to its systemic input side.

In an electrical control system of this kind, information is transmitted from one unit to another, ie. the devices share information with each other. This may mean that the information from a sensor that is connected to one control unit can be used by another control unit. Such sensors can then be either analog or digital and transmit the information to the control unit to which it is connected through different voltage levels.

In an electrical control system of this kind, it is important to be able to know with certainty whether the said earth connection of a first electronic control unit is correct or not, ie. that a reliable functional check of the earth connection can be made. An example of what could happen in the event that the said earth connection is lost is that in the case an inductive load is connected to such an electronic control unit and the load is earthed externally, ie not in the same place as the control unit, then the control unit can have problems with inputs when the inductive load is activated or deactivated. The ground plane in the control unit will then change in comparison with if the unit had been grounded correctly, which means that the information obtained from a sensor and will be forwarded to another electronic control unit will be incorrect.

However, the invention is not directed to solving this particular problem, but to generally determining whether a said ground connection of at least a first electronic control unit is at hand or not.

BACKGROUND ART US 2005/0268166 A1 describes an electrical control system of initially defined type, in which measurements are performed between the ground and the CAN line of the electrical control system to detect possible ground interruption on this line and then emit an error signal.

SUMMARY OF THE INVENTION The object of the present invention is to provide an electric control system and a method of initially defined types, which are improving in at least some respect relative to previously known such control systems and methods.

This object is achieved with respect to the electrical control system by providing such a control system with the features set forth in appended claims 1.

By measuring the internal voltage of the first electronic control unit and transmitting it to said further unit, which may also be an electronic control unit, and performing said comparison with a predetermined voltage level value value, the receiving unit will know if the first electronic control unit has a working ground connection or not. This means that the receiving unit then knows that it can rely on the information coming from the first electronic control unit, e.g. from a sensor connected to it. If, on the other hand, the said first value differs more than with the said predetermined amount from the predetermined voltage level value, then it must be assumed that the ground connection of the first electronic control unit is lost and appropriate measures can then be taken, such as notifying various units information coming from the first electronic control unit. Other measures may also be necessary, such as, for example, in the case of arranging the electrical control system of a motor vehicle, sending an alarm, such as lighting a warning light, to the driver of the vehicle.

According to an embodiment of the invention, said further unit is a said second electronic control unit with a second earth connection, the second electronic control unit is also provided with said first means for measuring voltage between the systemic input side of the second electronic control unit and said second ground connection, and said second means are designed to compare said first value with a predetermined voltage level value in the form of the measured voltage of the second electronic control unit. Thus, the core receiving controller compares its internal voltage with the internal voltage of the transmitting controller, and it is assumed that the transmitting controller has lost ground on the voltage difference resulting from this comparison being too large. In this case, the electrical system can have a number of said first and second electronic control units which in this way compare their internal voltages by sending information about it to each other, so that they become aware of whether they are to rely on other information coming from the respective electronic control unit.

According to another embodiment of the invention, said second electronic control unit is designed to transmit a second value voltage level between its input side and the second ground terminal to the first electronic control unit, and the first electronic control unit also has other means designed to compare the voltage level value thus received with a predetermined voltage level value in the form of said first value of the voltage level between its own input side and said first ground connection and to determine that said second electronic control unit has lost said second ground connection in case the comparison shows a difference between the compared values exceeding a predetermined amount. This embodiment thus describes the case that different electronic control units included in the electrical control system control each other by informing each other of their internal voltages to be transmitted.

According to another embodiment of the invention, said second means are designed to compare received voltage level value with one or more previously received voltage level values. By comparing the received voltage level value with the voltage level value normally received from an electronic control unit, it can be stated whether the earth connection of the electronic control unit is made. If e.g. previous voltage level values were at 24V + -0.2V and all of a sudden the received value is 22V, it can be assumed that the ground connection of the unit has been lost. In this case, by the unit receiving unit also comparing with its own internal voltage, an additional control can take place.

According to another embodiment of the invention, said second means are designed to determine that a ground connection is lost, said difference exceeds an amount which is 1% -15%, 1% -8%, 1% -5% or 2% -4% of said predetermined voltage level -value. For example, in the case of a typical voltage level value of 24V in a motor vehicle, a difference of about 1V may constitute a mentioned amount in the case of the units in question being grounded in essential places, while the amount could, however, be as high as 3V in the case of a control unit place far from other control units, as could be the case with a bus or other long vehicle.

According to another embodiment of the invention, the electrical control system comprises at least one sensor connected to the output side of the first electronic control unit and configured as a result of a performed sensing to send a voltage signal to this output side, and the first electronic control unit is designed to transmit said voltage signal. possibly after processing, further on its systemic input side to another electronic control unit included in the electrical control system. In this particular case, it is very important to be able to determine that the first electronic control unit has a correct earth connection, otherwise the information provided by the sensor transmits via the first electronic control unit can not be trusted.

According to another embodiment of the invention, said first electronic control unit has an output designed to be connected to an inductive load, and according to a further development of this embodiment the first electronic control unit is designed to effect conversion of a direct voltage via pulse width modulation and transmit the result of pulse width modulation to said input voltage. tive loads for driving it. In such a case, it is important to be able to determine with certainty that the first electronic control unit ground connection is correct, and this can then not be done via a conventional protection to detect lost ground connection of an electronic control unit, which is not able to detect this, because the voltage on the output side of the electronic control unit will change during the pulse width modulation whether the ground connection is lost or not, but the internal voltage on the input side of the electronic control unit will only change if the ground connection is lost, and this can then be detected in an electrical control system designed according to the invention .

The object of the invention is achieved with regard to the method by providing a method according to the appended independent method patent claims. What can be achieved by such a method and the advantages thereof appear from the discussion above of the various embodiments of the control system according to the invention.

Advantageous embodiments of the method according to the invention are stated in the dependent method patent claims.

The invention also relates to a computer program having the features listed in claim 11, a computer software product having the features listed in claim 12, an electronic control unit having the features listed in claim 13 and a motor vehicle according to claim 14.

Other advantageous features and advantages of the invention will become apparent from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the invention are described below by way of example with reference to the accompanying drawings, in which: Fig. 1 is a very schematic view illustrating an electrical control system according to a first embodiment of the invention, Fig. 2 is a Fig. 1 Fig. 3 is a flow chart showing a method according to one embodiment of the invention, and Fig. 4 is a schematic diagram of an electronic control unit for implementing one or more methods according to the invention. ningen.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION Fig. 1 shows very schematically certain parts of an electrical control system according to an embodiment of the invention, which here is indicated to be arranged in a motor vehicle 1, for example a truck or bus. The electrical control system has four electronic control units 2-5 designed to control electrical equipment included in the vehicle, and these control units are interconnected via a network 6, so that they can send information to each other. Each of the electronic control units has a ground connection 7-10 and is connected to a voltage source (not shown), such as a battery pack with a voltage of 24V.

By connecting the electronic control units for controlling different electrical equipment of the vehicle to each other in this way, they can share information from the sensors connected to the respective electronic control unit. This means that only a sensor is needed to produce the value of a parameter, even if the value of this parameter is needed in a plurality of electronic control units. In the figure, for the sake of simplicity, only the sensor 11 connected to the output side 12 of the electronic control unit 2 is shown, although most or all of the electronic control units should have one or more sensors connected to them. The sensor 11 is designed as a result of sensing performed therefrom to send a voltage signal to said output side 12 of the electronic control unit 2. The electronic control unit is designed to transmit this voltage signal, possibly after processing, further on its systemic input side via the network. 6 to the other electronic control units.

It is also shown how an inductive load 13, such as e.g. an electric motor or pump, is connected to the electronic control unit output 12. The electronic control unit 2 is designed to effect a conversion of direct voltage via pulse width modulation and send the result of the pulse width modulation to the inductive load for driving it. This will then cause the voltage at the output 12 to change in such pulse width modulation, which means that a sensor of a normal earth fault protection has no possibility of determining whether a ground fault, ie. if the electronic control unit 2 has lost its ground connection7, occurs. For this purpose, however, first means 14 are arranged to measure the internal voltage of the electronic control unit 2 between the earth connection 7 and the input side of the unit. Each electronic control unit has such a first means 14-17. The electronic control units are designed to transmit a first value of the internal voltage measured by the respective first means is passed on to the other electronic units in connection with a voltage signal from a sensor or other information being transmitted over the network 6. Each electronic control unit further has a second means 18-21 designed to compare that initial value with a predetermined voltage level value and to determine that the electronic control unit from which the first value was received has lost its ground connection in the event that the comparison shows a difference between the compared values exceeding a predetermined amount. In this case, the respective electronic control unit can compare the voltage value received with its own voltage value measured by the first-mentioned means or with a voltage value which normally comes from the transmitting unit. In this way, lost earth connections can be detected even when this occurs at the same time as an externally earthed inductive load is activated or deactivated.

Fig. 2 schematically illustrates an electrical control system according to another embodiment of the invention, and there the components corresponding to the embodiment in Fig. 1 are provided with the same reference numerals added with a 'Here illustrated two electronic control units 2', 3 'both has a sensor 11 ', 23 and an externally grounded inductive load 13', 22 connected to its outputs 12 ', 24. It is shown here that a monitoring electronic unit 25 is also connected to a network 6', which may be of any suitable type, such as CAN, Ethernet bus, Flexray bus, LIN bus etc. This monitoring unit can also be designed to compare the voltage values transmitted from the respective electronic control unit with predetermined voltage level values to determine whether any of the electronic control units 2 ', 3' have lost their ground connection. For this purpose, the monitoring unit has schematically indicated other means 26.

Fig. 3 shows a flow chart illustrating an embodiment of a method according to the present invention for functionally checking the earth connection of at least one electronic control unit included in an electrical control system for controlling electrical equipment. In a first step S1, the internal voltage of an electronic control unit is measured, and in parallel with this, in a second step S2, a sensor value is produced by this electronic control unit. In a third step Se, said voltage value and sensor value are forwarded to another electronic unit, which in a step S4 the receiver voltage value and the sensor value and in a step S5 compares the voltage value with its own voltage value. In step S6 the question is asked whether the difference between the compared voltage values is greater than a predetermined amount, and if the answer to this question is no it is determined in step S7 that the sensor value can be used, but the answer to the question is yes taken in step S8 appropriate action , which may, for example, be sending an alarm that the first electronic control unit has probably lost its ground connection.

Computer program code for implementing a method according to the invention is suitably included in a computer program which can be read into the internal memory of a computer, such as internal memory with an electronic control unit of an internal combustion engine. Such a computer program is suitably provided via a computer program product comprising a data storage medium readable by an electronic control unit, which data storage medium has the computer program stored thereon. Said data storage medium is, for example, an optical data storage medium in the form of a CD-ROM, a DVD disc, etc., a magnetic data storage medium in the form of a hard disk, a floppy disk, a cassette tape, etc., or a flash memory or a memory of the type ROM, PROM, EPROM or EEPROM.

Fig. 4 very schematically illustrates an electronic control unit 27 including an execution means 28, such as a central processing unit (CPU), for executing computer software. The execution means 28 communicates with a memory 29, for example the RAM type, via a data bus 30. The control unit 27 comprises end data storage medium 31, for example in the form of a Flash memory or a memory of the type ROM, PROM, EPROM or EEPROM. The execution means 28 communicates with the data storage medium 31 via the data bus 30. A computer program comprising computer program code for implementing a method according to the invention is stored on the data storage medium 31 in the form of a non-volatile storage medium.

The invention is of course not in any way limited to the embodiments described above, but a number of possibilities for modifications thereof should be obvious to a person skilled in the art without departing from the scope of the invention as defined in the appended claims.

Claims (14)

Electrical control system comprising o at least one first, electronically controlled electronic control unit (2-5, 2 ', 3') for controlling electrical equipment with a first ground connection (7-10, 7 ', 8'), o a further unit (2- 5, 2 ', 3', 25) in the form of a second electronic control unit for controlling electrical equipment or a monitoring electronic unit (25), which further unit is connected to a systemic input side of said first electronic control unit, and ø first means (14-17, 14 ', 15') designed to measure the internal voltage of said first electronic control unit between said first ground connection and said input side of this unit, characterized in that the first electronic control unit (2-5 , 2 ', 3') is designed to transmit a first value of said means measured internal voltage further said further unit (2-5, 2 ', 3', 25), said further unit having second means (18 -21, 18 ', 19') designed to compare said first value with a previous one determined voltage level value and to determine that said first electronic control unit has lost said first ground connection (7-10,7 ', 8') in case the comparison shows a difference between the compared values exceeding a predetermined amount, the control system further comprises at least one sensor (11, 11 ', 23) connected to the output side (12, 12', 24) of the first electronic control unit and designed to send a voltage signal to this output side as a result of sensing performed, and that the first electronic control unit (2, 2 ', 14 3') is designed to transmit said voltage signal, possibly after processing, further on its system input side to another electronic control unit included in the electrical control system. Electrical control system according to claim 1, characterized in that said further unit is said second electronic control unit (2-5, 2 ', 3') with a second ground connection, that the second electronic control unit is also provided with said first means (14 -17, 14 ', 15') for measuring the voltage between a systemic input side of the second electronic control unit and said second earth connection, and said second means (18-21, 18 ', 19') are designed to compare said first value with a predetermined voltage level value in the form of the measured voltage of the second electronic control unit. 3. An electrical control system according to claim 2, characterized in that said second electronic control unit (2-5, 2 ', 3') is designed to transmit a second value of the voltage level between its input side and the second ground connection (7-10, 7 '). , 8 ') to the first electronic control unit (2-5, 2', 3 '), and that the first electronic control unit also has second means (18-21, 18', 19 ') designed to compare the voltage level value thus received with a predetermined voltage level value in the form of said first value of the voltage level between its own input side and said first ground connection and determining that said second electronic control unit has lost said second ground connection in case the comparison shows a difference between the compared values exceeding a predetermined amount. Electric control system according to any one of the preceding claims, characterized in that said second means (18-21, 18 ', 19') are designed to compare received voltage level value with one or more previously received voltage level values. Electric control system according to any one of the preceding claims, characterized in that said second means (18-21, 18 ', 19') are designed to determine that a ground connection is lost, said difference exceeds an amount which is 1% -15% , 1% -8%, 1% -5% or 2% -4% of the said predetermined voltage level value. Electrical control system according to any one of the preceding claims, characterized in that said first electronic control unit (2, 2 ', 3') has an output (12, 12 ', 24) designed to be connected to an inductive load (13, 13). ', 22). Electrical control system according to claim 6, characterized in that said first electronic control unit (2, 2 ', 3') is designed to effect a conversion of a direct voltage via pulse width modulation and transmit the result of the pulse width modulation to said inductive load (13, 13 ', 22) for driving it. Method for function control of ground connection of at least one first electronic control unit (2-5, 2 ', 3') included in an electrical control system for controlling electrical equipment, the control system also comprising an additional unit (2-5 , 2 ', 3', 25) in the form of a second electronic control unit for controlling electrical equipment or a monitoring electronic unit, which further unit is connected to a single system input side of the first electronic control unit, and the control system also comprises at least one sensor (11, 11 ', 23) connected to the output side (12, 12', 24) of the first electronic control unit, which comprises measuring the internal voltage of said first electronic control unit (2-5, 2 ', 3') between said ground connection (7-10, 7 ', 8') and said input side of this unit, and transmitting a first value of the measured internal voltage on to said further unit (2-5, 2 ', 3', 25), characterized in that it also included takes to v of said further unit comparing said initial value with a predetermined voltage level value, ø determining that a malfunction exists at said earth connection in case the comparison in the previous step shows a difference between the compared values exceeding a predetermined amount, ø sending a voltage signal to it the output side (12, 12 ', 24) of the first electronic unit as a result of sensing of the sensor (11, 11', 23) and transmitting said voltage signal on from the first electronic control unit (2, 2 ', 3), possibly after pickling, on the input side 17 of the latter control unit to another electronic control unit included in the electrical control system. A method according to claim 8, wherein said further unit is said second electronic control unit with a ground connection, characterized in that it comprises the steps of measuring the voltage between a system input side and the second electronic control unit (2-5, 2 ', 3). ') and its ground connection (7-10, 7', 8 '), and comparing said first value with a predetermined voltage level value in the form of the measured voltage of the second electronic control unit. Method according to claim 9, characterized in that it comprises the step of transmitting from the second electronic control unit (2-5, 2 ', 3') a second value of the voltage level between this input side and the earth connection (7-10, 7). ', 8') to the first electronic control unit, ø of the first electronic control unit (2-5, 2 ', 3') comparing the voltage level value thus received with a predetermined voltage level value in the form of said first value of the voltage level between the first the input side and ground connection of the electronic control unit (7-10, 7 ', 8'), and ø determine that there is a malfunction of said ground connection of the other electronic control unit, in which case the latter comparison shows a difference between the compared values exceeding a predetermined amount. 11. 12. 13. A computer program that is rechargeable directly into the internal memory of a computer, the computer program comprising computer program code for causing the computer to control the steps of any of claims 8-10 when said computer program is run on the computer. The computer program product comprises a durable data storage medium which is readable. of a computer, the computer program code of a computer program according to claim 11 being stored on the data storage medium. Electronic control unit for electrical equipment comprising an execution means (28), a memory (29) connected to the execution means and a data storage medium (31) connected to the execution means (28), the computer program code of a computer program according to claim 11 being stored on said data storage medium (31). Motor vehicle, such as a wheeled motor vehicle, for example a single truck or bus, characterized in that it comprises an electric control system according to any one of claims 1-7.