CN109818339B

CN109818339B - Method for protecting bus stations in a motor vehicle against overload and circuit arrangement for carrying out the method

Info

Publication number: CN109818339B
Application number: CN201811228900.6A
Authority: CN
Inventors: M.弗里德里希; A.克雷思; M.多林
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2017-11-22
Filing date: 2018-10-22
Publication date: 2021-03-09
Anticipated expiration: 2038-10-22
Also published as: CN109818339A; DE102017220870A1

Abstract

The invention relates to a method for overload protection of a bus station in a motor vehicle and to a circuit arrangement for carrying out the method. The invention relates to a method for overload protection for at least one bus station (11,12,13) in a motor vehicle (K), said bus station being connected to the vehicle network of the motor vehicle. If necessary, the bus station can be electrically decoupled from the on-board network by means of at least one safety device (15). The invention proposes that the current (I) flowing to the bus station is measured and the measured current value is transmitted to at least one first evaluation and communication device (18), which is or can communicate with the bus station. When a specific first limit value of the measured current value is reached, at which it can be concluded that an overload or an abnormal load of the bus station is imminent.

Description

Method for protecting bus stations in a motor vehicle against overload and circuit arrangement for carrying out the method

Technical Field

The invention relates to a method for overload protection of at least one bus station in a motor vehicle. The invention also relates to a circuit arrangement for carrying out the method.

Background

The large number of consumers present in today's motor vehicles is usually supplied with power via the on-board network. As is known, such a vehicle-mounted network also has a bus system, which may be designed, for example, as a CAN bus and/or a LIN bus. A plurality of bus stations are connected to the on-board network by bus lines leading to the bus. A bus station in the sense of the present invention is to be understood as an intelligent consumer. Which itself has intelligence, for example in the form of a control unit, and at least one component controllable by the intelligence. In this case, the control unit may be mounted in a common housing together with the controllable components. However, this is not mandatory. For example, as a bus station in the sense of the present invention, an airbag control unit with an ignition device associated therewith or an air conditioning control unit with a fan motor associated therewith can be envisaged.

In order to protect bus stations and the power lines leading to these bus stations from overload, overload protection methods for bus stations connected to an on-board network are known from the prior art.

Thus, for example, DE 19625401C 1, which also forms a feature of the preamble of claim 1, describes a bus system for data transmission, in which a plurality of bus stations are connected to a data bus. In particular, one of the bus stations is designed as an evaluation device of the occupant protection system. The other two bus stations serve as ignition devices, which are associated with the restraint devices of the occupant protection system. The electrical decoupling of the bus station from the on-board network can be achieved, if required, by means of a so-called multi-fuse. In normal operation, it has a low ohmic value, which becomes high ohmic in the case of a relatively large current, which represents a short circuit on the associated bus line. If the current then drops back to a relatively low value, the resistance of the multi-fuse also assumes a low ohmic state again. Thus, the multiple fuse safety is reversible compared to a blown safety.

A method for testing a multi-chip module with an integrated semiconductor memory is known from DE 102004039831 a1, in which the function of the memory cells in the integrated semiconductor memory is tested and the addresses of the memory cells of the integrated semiconductor memory identified as defective are stored in the integrated circuit. In particular, the integrated circuit has a block of electrically programmable connections or electrically programmable fuses (E-fuses) which can be switched permanently from low-resistance to high-resistance or vice versa by applying energy pulses in their conductive state. This method can also be performed after the end of the manufacture of the multi-chip module.

If a write or read access is now made to a memory cell identified as defective, this access is transferred by the multiplexer to another memory cell of the integrated semiconductor memory which is not identified as defective.

Finally, DE 60110297T 2 discloses a memory device with an electrically programmable fuse (E-fuse). The electrically programmable safety device is also used here to distinguish redundant addresses of memory elements identified as defective, thereby ensuring that the memory device does not operate incorrectly during operation.

Disclosure of Invention

The object of the present invention is to provide an overload protection method for at least one bus station in a motor vehicle, which makes the bus station available for a long time even in critical load states.

Another object of the invention is to provide a suitable circuit arrangement for carrying out the method.

The technical problem to be solved by the method is solved by a method according to the features of the invention. The technical problem to be solved by the circuit arrangement is solved by a circuit arrangement having the features of the invention.

The invention is based on a method for overload protection of at least one bus station in a motor vehicle. At least one bus station is connected to the on-board network of the motor vehicle. The on-board network comprises a bus, to which the bus stations are connected by means of bus lines. For example, the bus CAN be designed as a CAN bus (Controller Area Network) or also as a LIN bus (Local Interconnect Network). If necessary, the at least one bus station can be electrically decoupled from the on-board network by means of at least one electrical safety device.

The invention now proposes that the current flowing to the at least one bus station is measured and that the measured current value is transmitted to the at least one first evaluation and communication device. The first evaluation and communication device communicates with or can communicate with the bus station. Furthermore, the first evaluation and communication device causes the bus station to reduce its functional range or its power when a specific first limit value of the measured current value is reached, at which first limit value it can be concluded that an overload of the bus station is imminent or at least that an abnormal load of the bus station is inferred. By reducing the functional range or power of the bus station, the power consumption of the bus station is reduced.

Thus, according to the invention, appropriate countermeasures are taken before an imminent overload of a bus station or an imminent load of the power line associated therewith, in order to ensure as long a use of the bus station as possible.

For example, the power reduction may be such that the bus station still outputs only a fraction of its maximum possible power, for example only 75% or 50%. For example, it is conceivable that the seat heating can no longer be operated at the highest heating level, but can only still be operated at a moderate heating level.

It is also conceivable that the bus station configured as a control unit reduces its functional range such that control signals are still provided only to a smaller number of components, for example only to so-called Prio-1 components.

Thus, in critical conditions, the bus station is not immediately switched off, it can remain operational for a longer time (with a smaller power range).

According to a first further development of the method, the electrical safety device interrupts the current flowing to the bus station when a specific second limit value of the measured current is reached, at which an overload of the bus station can be inferred. In this way, an optimal protection of the compromised bus station can be achieved.

According to one advantageous embodiment of the method, the bus station is associated with at least one second evaluation and communication device, or the bus station itself has an evaluation and communication device which communicates with the first evaluation and communication device. The second evaluation and communication device transmits to the first evaluation and communication device a specific first limit value of the measured current value, at which it can be concluded that an overload or an abnormal load of the bus station is imminent. The second evaluation and communication device calculates the first limit value as a function of the load state of the currently existing bus station.

In this embodiment, therefore, instead of transmitting the static limit values, a dynamic calculation of the limit values is carried out, which takes into account the actual load state of the bus station during its operating time, which is also dependent on the ambient temperature, for example.

It is conceivable here for the second evaluation and communication device to also transmit a second limit value to the first evaluation and communication device, at which second limit value it can also be inferred that the bus station is overloaded. In this case, the second evaluation and communication device also calculates a second limit value as a function of the load state of the currently existing bus station. This also allows a better consideration of the actual load conditions.

In order to facilitate a later diagnosis of errors or error causes, it is proposed that, when the first and/or second limit value is reached, the load state of the bus station which was present when the respective limit value was reached is stored in at least one preferably non-volatile memory. For example, the memory may be part of the second evaluation and communication device. The load state to be stored can be characterized, for example, by the current power consumption of the bus station or the number and type of functions currently controlled by the bus station.

As already mentioned, the invention also relates to a circuit arrangement for carrying out the method according to the invention.

The invention is based on a circuit arrangement in the on-board network of a motor vehicle. In the circuit arrangement, at least one bus station is preferably connected to a bus of the on-board network via a corresponding bus line. Furthermore, at least one electrical safety device is provided, by means of which electrical decoupling of the bus station from the on-board network bus can be achieved.

According to the invention, at least one current measuring unit is present, with which the current flowing to the bus station can be measured. The measured current values can be transmitted to at least one first evaluation and communication device, which can communicate with the bus station. The communication is carried out such that the bus station can be reduced in its functional range or its power depending on the measured current value.

The method according to the invention can be carried out well with such a circuit arrangement. In this way, the availability of the bus station for as long as possible can be ensured.

In a very advantageous embodiment of the inventive concept, the electrical fuse is a reversibly operating fuse. As reversibly operating safety devices, i.e. safety devices that can be used several times, for example, electrically programmable safety devices (E-fuses) can be considered. It can be switched by a suitable switching control device, which in turn can be controlled by the evaluation and communication unit. In this way, the safety device does not have to be replaced even after an overload situation has occurred, which results in a reduction in maintenance costs.

It is also possible to communicate between the evaluation and communication unit and the reversibly operating safety device or the switching control device associated therewith, so that at a specific current value the reversibly operating safety device is caused to interrupt the power loss of the bus station. Thus, protection against overload is also provided at the same time.

The circuit arrangement can be expanded in the following manner: there is at least one second evaluation and communication device associated with the bus station or of the bus station itself, which can communicate with the first evaluation and communication device. By means of the second evaluation and communication device, the current load state of the bus station can be detected. In this case, a limit value of the measured current can be calculated by the second evaluation and communication device and transmitted to the first evaluation and communication device, at which limit value the functional range or the power of the bus station is reduced or even the current flow to the bus station is interrupted by a reversibly operating safety device.

By means of such an extended design of the circuit arrangement, an optimum adaptation to the actually present load can be achieved.

A further embodiment of the inventive concept proposes that there are a plurality of bus stations and that the bus stations are designed as control units, wherein each bus station is associated with at least one component to be controlled. The advantages of the method according to the invention can thus be utilized well. For example, it is thus possible to inform a plurality of control units about their load status and, in the event of an imminent overload, to reduce their functional range accordingly ("functional degradation"). This in turn leads to a reduction in power consumption.

Finally, a further advantageous embodiment of the circuit arrangement provides that at least one fuse comprises the current measuring unit, the first evaluation and communication device and a switching control device, by means of which the fuse can be switched and the current flow to the bus station can be interrupted.

This structure makes it possible to reduce the required components and also makes the circuit arrangement less susceptible to interference.

Drawings

Preferred embodiments of the invention are shown in the drawings and will be explained in more detail in the following description with the aid of the drawings. Other advantages of the invention will thus become further apparent. The same reference numbers, even in different drawings, indicate the same, similar or functionally identical elements. In this case, corresponding or similar features and advantages can be achieved even if they are not described or referred to repeatedly. The drawings are not always to scale. In some of the drawings, the scale may be shown exaggerated in order to more clearly highlight features of the embodiments.

Figure 1 schematically shows a circuit arrangement for performing the method in a first embodiment,

fig. 2 schematically shows a circuit arrangement for performing the method in a second embodiment, an

Fig. 3 schematically shows a diagram for finally explaining the method.

Detailed Description

Reference is first made to fig. 1. In the figure, a motor vehicle K is shown, which has a circuit arrangement 1.

In the circuit arrangement 1, a bus 10 CAN be seen, which CAN be designed, for example, as a CAN or LIN bus.

The

bus stations

11,12 and 13 are connected to the bus 10 by bus lines 14. The bus stations 11 to 13 are formed in the present exemplary embodiment as control units which control the end consumers (electrical components) in the motor vehicle K associated therewith.

Such end-use electrical devices may be, for example, heating and air conditioning systems, seat adjusting devices, components of restraint systems, and/or components of audio systems.

The bus station 11 is thus connected to the component 11-1 via the signal and control lines 20, the bus station 12 is connected in the same way to the components 12-1 and 12-2 to be controlled, and the bus station 13 is finally connected to the components 13-1,13-2 and 13-3 to be controlled. In contrast to this embodiment, it is also conceivable to mount each of the bus stations 11 to 13 together with the components 11-1, 12-1 and 12-2 or 13-1 to 13-3 respectively associated therewith in a common housing.

17 and 17' denote power lines, through which the bus stations 11 to 13 are fed with a current I or partial currents I1 to I3.

The required current I received by the bus stations 11 to 13 varies, of course, depending on the components 11-1 to 13-3 controlled by the bus stations 11 to 13 during the driving mode.

The theoretically possible maximum current can be estimated according to the maximum number of components to be controlled and/or the possible maximum power consumption. As a rule of thumb, the average current I occurring in actual operation is significantly lower than this, since not all components are always controlled simultaneously or all components are operated at maximum power.

In order to protect the bus stations 11 to 13 and the components 11-1, 12-1 and 12-2 and 13-1 to 13-3 associated therewith from overload and also to protect the power lines 17, 17', an electrical fuse 15 (so-called E-fuse), which preferably operates reversibly, is connected in front of them in the circuit arrangement 1.

The safety device 15 can be reversibly switched by means of a switching control device 16. The switching control device 16 can in turn be controlled by an evaluation and communication unit 18.

The current I flowing in the main power line 17 is continuously measured by the current measuring unit 19. The measured current values are transmitted to the evaluation and communication unit 18.

In the evaluation and communication unit 18, two limit values IG1 and IG2 of the current I are stored in a storage unit (see also fig. 3), which is not further shown.

In contrast to the exemplary embodiment shown, it is also conceivable to integrate the safety device 15, the switching control device 16, the evaluation and communication unit 18 and the current measuring unit 19 in one unit. In contrast to this exemplary embodiment, it is also conceivable to design the safety device 15 as a conventional fuse safety device. In this case, the switching control device 16 is not present, and a signal-technical connection of the safety device 15 to the evaluation and communication unit 18 is not necessary or useful.

At this point, if, during driving operation of the motor vehicle K, a first limit value IG1 for the current I is reached, at which first limit value IG1 it can be concluded that the bus stations 11 to 13 or one of the components associated therewith or also one of the power lines 17, 17' leading to these bus stations is imminent or an overload or abnormal load is imminent, the evaluation and communication unit 18 communicates with the evaluation and communication unit 21 (indicated by the dashed line) of the bus stations 11 to 13 in the following manner:

which enables the bus stations 11 to 13, or at least the associated bus station, to still control only the component with the highest priority (Prio1 component) of the controllable components 11-1 to 13-3, respectively, or to still operate only at reduced power.

This suddenly causes the current measured by the current measuring unit 19 to drop below the first limit value IG1 again, and the load of the circuit arrangement 1 is moved again within the "green" range.

This method therefore has the advantage that countermeasures can be taken immediately before an overload is imminent, and that the reversibly operating safety device 15 does not need to be switched to be useless. That is to say this would lead to a complete breakdown of the bus stations 11 to 13 and thus of the components 11-1 to 13-3.

When a load situation occurs in which the current measuring unit 19 measures the second limit value IG2 and thus determines an overload, the switching control device 16 switches the safety device 15 such that the current I is completely interrupted.

In contrast to this exemplary embodiment, it is also conceivable, instead of the fixed limiting values IG1, IG2, to continuously determine these limiting values as a function of the current load situation and to store them quickly in the evaluation and communication unit 18.

For this purpose, each evaluation and communication unit 21 is required to transmit the current load state of its associated bus station to the evaluation and communication unit 18 via the bus 10. The evaluation and communication unit 18 calculates therefrom a dynamic (i.e. time-varying) limit value of the current I and stores it continuously in a volatile memory (not shown in detail).

Furthermore, the method corresponds to the preceding description when one of the limit values is reached.

This variant of the method has the advantage of higher precision and thus of optimal utilization of the bus stations 11 to 13.

A circuit arrangement 1' of a further embodiment is now described with reference to fig. 2.

In contrast to the previous exemplary embodiments, in each case a reversibly operating safety device 15 is connected in front of each bus station 11 to 13 in the power line 17' respectively associated therewith.

Furthermore, a switching control device 16, a current measuring unit 19 and an evaluation and communication unit 18 are integrated in each safety device 15. The components mentioned can be integrated, for example, in a common housing and/or on a common circuit board.

Likewise, for this variant, two further sub-variants of the method are conceivable:

first, two limit values for the current I1, I2 or I3 flowing to the

respective bus station

11,12 or 13 can be stored for each evaluation and communication unit 18 depending on the component 11-1 to 13-3 associated with the

bus station

11,12 or 13. For each evaluation and communication unit 18, this is done analogously to the method in the previous embodiment.

However, the circuit arrangement 1' offers the advantage of a higher level of detail. Only the functional range of a bus station in a critical load state or an already unacceptable load state is reduced or the current to the bus station is interrupted, respectively.

Secondly, in the circuit arrangement 1', a better adaptation to the actual operating conditions can also be achieved when each of the evaluation and communication units 21 in turn informs the respective evaluation and communication unit 18 of the actually existing load state. Thus, here, for each bus station 11 to 13, the dynamic current limit value can be determined similarly to the first embodiment.

Finally, the method according to the invention is briefly outlined again with reference to fig. 3:

here, it can be seen that the current I flowing to the bus station is plotted on the vertical axis and the time t is plotted on the vertical axis.

Two limit values IG1 and IG2 of the flowing current I are qualitatively depicted. Below the first limit value IG1, an "allowed range" B1 is formed, whereas above the second limit value, a circuit is defined as an "forbidden range" B3.

A "critical range" B2 is defined between limit values IG1 and IG 2.

After the start of the vehicle K, it is conceivable, for example, for the current I to have a schematically illustrated time profile I (t). It can be seen that the current I is operated within the allowable range B1 before the time point t 1. At the time t1, the current measuring unit 19 measures a current I, which corresponds to a first limit value IG1 as a function of the comparison in the evaluation and communication unit 18.

The evaluation and communication unit 18 then sends instructions to the

respective bus station

11,12 or 13 to reduce its functional range. This functional reduction results in a reduction of the power consumption of the respective bus station at time t2 (typically in the millisecond range after time t 1), so that the current I again falls below the first limit value IG 1.

At point in time t3, a further reduction in the current I occurs, for example, as a result of the operator manually deactivating the component.

If, at the point in time t4, the current value I suddenly increases, for whatever reason, until the second limit value IG2 is reached, a signal is sent by the evaluation and communication unit 18 to the switching control device 16 to carry out the switching of the safety device 15, i.e. to carry out the interruption of the current I.

The method according to the invention therefore allows the bus stations 11 to 13 to operate for as long as possible, even if critical load situations occur during this time.

With the vertical double arrow shown, it is shown that the stored critical range B2 can be changed in a time-dependent manner with a dynamic range D when the additional evaluation and communication unit 21 of the bus station mentioned is used.

List of reference numerals

1. 1' Circuit arrangement

10 bus

11-13 bus station

11-1 bus station to be controlled

Component to be controlled of a 12-1,12-2 bus station

Component to be controlled of a 13-1 to 13-3 bus station

14 bus line

15 reversibly working safety device (E-fuse)

16 switching control device

17. 17' power line

18 evaluation and communication unit

19 Current measuring unit

20 signal and control lines

21 evaluation and communication unit

B1 allowable Range

Critical range of B2

Forbidden range of B3

Dynamic range of D

I current

I1-I3 partial current

First limit value of IG1 Current

Second limit value of IG2 Current

K car

time t

time points t1-t3

Claims

1. An overload protection method for at least one bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) in a motor vehicle (K), which bus station is connected to an on-board network of the motor vehicle (K), wherein an electrical decoupling of the bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) from the on-board network is initiated or can be initiated if necessary by means of at least one securing device (15), characterized in that a current (I) flowing to the bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) is measured and the measured current value is transmitted to at least one first evaluation and communication device (18), said first evaluation and communication device communicates with the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) or is capable of communicating with the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) and, when a specific first limit value (IG1) for the measured current value is reached, causes the bus stations (11,12,13) to reduce their functional range or their power in such a way that the power consumption of the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) is reduced, it being possible to conclude that the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) an impending overload or abnormal load,

wherein the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) are associated with at least one second evaluation and communication device (21), which second evaluation and communication device (21) communicates with the first evaluation and communication device (18) and transmits the specific first limit value (IG1) of the measured current values to the first evaluation and communication device (18), under which specific first limit value (IG1) it can be concluded that an overload or an abnormal load is imminent at the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3), wherein the second evaluation and communication device (21) determines, from the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) calculating the first limit value (IG1),

wherein the second evaluation and communication device (21) also transmits a second limit value (IG2) to the first evaluation and communication device (18), wherein the second evaluation and communication device (21) calculates the second limit value (IG2) from the currently existing load state of the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2, 13-3).

2. Method according to claim 1, characterized in that the current (I) to the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) is interrupted by a safety device (15) when a second limit value (IG2) of the measured current (I) is reached, at which an overload of the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) can be inferred.

3. Method according to one of the preceding claims, characterized in that upon reaching the first and/or second limit value (IG1, IG2), the load state of the bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) present upon reaching the respective limit value (IG1, IG2) is stored in at least one memory.

4. A circuit arrangement in a vehicle network of a motor vehicle (K) for carrying out the method according to one of the preceding claims, wherein at least one bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) is connected to a bus (10) of the vehicle network, wherein at least one securing device (15) is present, by means of which electrical decoupling of the bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) from the bus (10) of the vehicle network can be achieved, characterized in that at least one current measuring unit (19) is present, by means of which current measuring unit (19) a current flowing to the bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3), and the measured current value can be transmitted to at least one first evaluation and communication device (18), which first evaluation and communication device (18) can be connected to a bus station (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) in such a way that the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) to reduce its functional range or its power,

there is at least one second evaluation and communication device (21) associated with the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3), which second evaluation and communication device (21) can communicate with the first evaluation and communication device (18) and by means of which a current load state can be detected, wherein a limit value (IG1, IG2) of the measured current (I) can be calculated by means of the second evaluation and communication device (21) and can be transmitted to the first evaluation and communication device (18), at which limit value the functional range or the power of the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) is reduced, or the current flow to the bus stations (11, 11-1; 12,12-1, 12-2; 13,13-1,13-2,13-3) is interrupted by a reversibly operating safety device (15).

5. A circuit arrangement as claimed in claim 4, characterized in that a plurality of bus stations (11,12 and 13) are present and are designed as control units, wherein each bus station (11,12,13) is associated with at least one component (11-1; 12-1, 12-2; 13-1,13-2,13-3) to be controlled.

6. A circuit arrangement as claimed in claim 4 or 5, characterized in that the at least one fuse device (15) comprises the current measuring unit (19), the first evaluation and communication device (18) and a switching control device (16), by means of which switching control device (16) the fuse device (15) can be switched and the current flow to the bus stations (11,12,13) can be interrupted.