DE102021200169A1 - Method for monitoring the energy supply of a motor vehicle - Google Patents

Abstract

The invention relates to a method for monitoring the energy supply of a motor vehicle, in particular with an automated driving function, with at least one energy store (12) being provided which supplies at least one safety-relevant consumer (16), with at least one electronic load distributor (18) being provided via which the load (16) is controlled and secured, the energy store (12) being connected to the load distributor (18), with an alternative supply of the safety-relevant load (16) being a DC-DC converter (22) which can be supplied from a further energy store (24). is connected to the electronic load distributor (18), and at least one further consumer (9) is supplied with energy between the DC-DC converter (22) and the electronic load distributor (18), with a voltage (U1) supplying the further consumer (9) being a limit voltage (Ug) is lowered, at which a degradation, esp special shutdown or reduction of power consumption, the other consumer (9) takes place (step 105), wherein an electrical parameter (I, U) of the other consumer (9) is detected and based on the electrical parameter (I, U) on a proper or erroneous degradation of the other consumer (9) is closed.

Description

The invention relates to a method for monitoring the energy supply of a motor vehicle according to the generic type of the independent claim.

State of the art

From the WO 2019/145087 A1 a method for monitoring the energy supply of a motor vehicle with automated driving functions is already known. Depending on a load profile for bringing the vehicle into a safe state, at least one parameter of the energy store is predicted and the associated mode of operation and/or the automated driving functions are enabled depending on the predicted parameter of the energy store. The predicted parameter is determined as a function of a base load and/or a switch-off potential of the consumer that is not required for the mode of operation.

The object of the invention is to increase the reliability and at the same time the availability, in particular of automated driving functions, and the required energy supply in a simple manner. This object is solved by the features of the independent claim.

Disclosure of Invention

The fact that a voltage supplying the other consumer is lowered to a limit voltage at which degradation, in particular shutdown or reduction of power consumption, of the other consumer takes place, and that an electrical parameter of the other consumer is detected and based on the electrical parameter to a proper or erroneous degradation of the additional consumer is closed, the reliability of the alternative energy supply of the safety-relevant consumer can be further increased. The energy supply of the additional consumer is deliberately selected so that the safety-relevant consumer can be supplied with sufficient electrical energy in order to be able to reliably carry out safety-related maneuvers such as dynamic load maneuvers such as braking/steering maneuvers for the transition to a safe state. The method described monitors the voltage-dependent degradation of the other consumers in a particularly simple manner, so that in particular an ASIL-C-capable on-board power supply system is guaranteed with little additional effort.

In an expedient development, the DC-DC converter and/or the additional consumer is disconnected from the energy store, in particular before the voltage is reduced to the limit voltage. In this way, the voltage-supporting effect of the energy store can be deliberately canceled in order to check the degradation capability of the other consumers.

In an expedient development, it is provided that the additional consumer is run up to a specific power consumption, particularly preferably maximum power consumption, in particular after the DC-DC converter and/or the further consumer has been disconnected from the energy store. This makes it particularly easy to check whether the additional consumer is still working properly, regardless of the degradation to be checked later.

In an expedient development, an electrical parameter of the additional consumer is recorded when the additional consumer has been ramped up to a specific power consumption and/or after the voltage has been lowered to the limit voltage and/or the degradation of the additional consumer has taken place. The proper functioning of the additional consumer in the different operating states (normal operation, degradation) is preferably monitored, for example, on the basis of the current consumption. This is particularly preferably done by the DC-DC converter, which is provided in any case for coupling the dual-voltage vehicle electrical systems present in certain architectures and in any case detects the required parameters in this context.

In an expedient development, at least one separating means is provided in the electronic load distributor, which connects the DC-DC converter to the safety-relevant consumer to ensure the electrical supply of the safety-relevant consumer. This separating agent further increases the security of the energy supply to the safety-relevant consumer, since, for example, faults in an on-board network branch do not affect the on-board network branch with the safety-relevant consumers due to the separability.

In an expedient development, the parameter determined at the DC-DC converter and/or at the electronic load distributor and/or at the other consumer, in particular current and/or voltage, is transmitted to the electronic load distributor and/or an energy management system or another control device. There, the evaluation can be made as to whether the additional consumer is working properly or is degraded.

In an expedient development, a countermeasure such as transferring the vehicle to a safe state and/or activating a warning notice or a warning display and/or setting an error entry takes place if it is concluded that the additional consumer has been degraded incorrectly. The safety of the arrangement is further improved since countermeasures are initiated in good time in the event of faulty operation.

In an expedient development, a switching device, in particular a semiconductor switch, is used in the electronic load distributor to control and safeguard the safety-relevant consumer, with certain parameters such as current, voltage, temperature or the like being recorded for safeguarding purposes and the safety-relevant consumer being switched off if impermissible limit values are exceeded is made. The safety-relevant consumer can be protected from impermissible operating states and thus from destruction by the electronic load distributor.

Further expedient developments result from further dependent claims and from the description.

character list

• 1 ein Bordnetz, bei dem das Verfahren zur Überwachung des Energiespeichers beispielhaft implementiert ist sowie
• 2 ein Ablaufdiagramm des Verfahrens.

Show it:

• 1 a vehicle electrical system in which the method for monitoring the energy storage device is implemented as an example, and
• 2 a flowchart of the process.

embodiment of the invention

The invention is shown schematically using an exemplary embodiment and is described in detail below with reference to the drawing.

the 1 shows a possible topology of an energy supply system, consisting of a basic vehicle electrical system 10, which includes an energy store 12, in particular a battery 12 with an associated battery sensor 14, and a plurality of consumers 16, which are secured or controlled or supplied by an electronic load distributor 18. The energy store 12 is also connected to the electronic load distributor 18 . The electronic load distributor 18 includes a plurality of switching means 15, each of which controls, protects or supplies safety-relevant consumers 16 in particular. Switching means 15 could be semiconductor switches which, for example, function as an electronic fuse according to certain criteria such as (overvoltage, (over)current, temperature, etc.) and disconnect the respective protected consumer 16 from the power supply in the event of impermissible operating states. Switching means 15 are each connected in parallel. A further load distributor 13 is connected to a further switching means 15 of the electronic load distributor 18, for example, via which further consumers 17 are protected (e.g. via fuses) and supplied with energy in a targeted manner. The consumers 17 can be, for example Lighting, windscreen wipers or those consumers 17 that are used, for example, after a crash.Furthermore, the electronic load distributor 18 includes a separating means 19. The separating means 19 can preferably be a semiconductor switch, for example two serial Hal lead switches with diodes arranged antiparallel to each other (back-to-back). The separating means 19 serves to separate the electronic load distributor 18 from the vehicle electrical system part 20, for example in the event of a fault.

The electronic load distributor 18 is able to determine corresponding parameters such as voltage Uv, current Iv of the consumers 16. In addition, the electronic load distributor 18 is also able to determine corresponding parameters of the energy store 12 such as voltage Ub and/or current Ib and/or temperature Tb. For this purpose, the electronic load distributor 18 contains the appropriate sensors. The electronic load distributor 18 also has appropriate processing means for storing and evaluating detected variables. Alternatively, the evaluation could also take place in another control unit. The electronic load distributor 18 can also record the current or voltage present at the input (at the so-called terminal 30_0).

Furthermore, the electronic load distributor 18 is able, depending on the state of the energy store 12, to supply signals on the basis of which the transition to a safe state is initiated. Then, for example, a higher-level control unit initiates a safe stop of the vehicle (moving to the next parking space, immediate stop at the hard shoulder, etc.) and exits the autonomous driving mode.

Consumers 16 controlled by electronic load distributor 18 could, for example, include safety-related vehicle functions such as braking, steering, etc. The safety-relevant consumers 16 could, for example, also cover important functions in a functionally redundant manner.

The electronic load distributor 18 is on the side remote from the energy store 12 with a further load distributor 11 electrically conductively connected. The other load distributor 11 is used to control or protect other consumers 9. The other load distributor 11 is connected to a DC-DC converter 22. The DC-DC converter 22 serves to convert the voltage between the first basic vehicle electrical system 10, which supplies the consumers 9, 16, 17 with a voltage level U1 and a voltage level U2 of another vehicle electrical system 20. The basic vehicle electrical system 10 has a different vehicle electrical system than the other vehicle electrical system 20, for example a high-voltage vehicle electrical system , a lower voltage level U1, for example, it can be a 12 V vehicle electrical system. In order to ensure the energy supply, in particular to the safety-relevant consumers 16, at least one of the consumers 9 can be degraded depending on the voltage, in particular in normal operation, for example by reducing, limiting or switching off the power consumption. The voltage-dependent degradation of the consumer or consumers 9 is as follows in connection with 2 described. If the degradation is working correctly, for example in the event of a fault in the energy store 12, an alternative energy supply can be ensured via the DC-DC converter 22 and the switching means 19, in particular for the safety-relevant consumers 16.

The high-voltage on-board electrical system 20 includes, for example, an energy store 24, for example a high-voltage battery, possibly with an integrated battery management system, a load 26 shown as an example, for example a comfort consumer such as an air conditioning system supplied with a higher voltage level, and an electric machine 28 understood in this context, a voltage level U2, which is higher than the voltage level U1 of the basic vehicle electrical system 10. For example, it could be a 48-volt vehicle electrical system. Alternatively, even higher voltage levels could be involved in vehicles with a purely electric drive.

At least one or more, in particular, safety-relevant channels can be connected to the basic vehicle electrical system 10 . The safety-relevant channels could each be connected to the basic vehicle electrical system 10 via a further electronic load distribution. The additional electronic load distributor could serve to protect, control, and safely and reliably switch off and supply safety-relevant consumers or the electronic energy network distribution. These consumers could be supplied with functional redundancy through different safety-relevant channels. In addition, the further electronic load distributor can be able to detect the consumer currents flowing or the voltages present. This embodiment, briefly described but not shown, could be provided for a high-availability design, for example for autonomous driving to increase safety.

By way of example, a battery or accumulator is described as a possible energy store 12, 24 in the exemplary embodiment. Alternatively, however, other energy stores suitable for this task, for example on an inductive or capacitive basis, fuel cells, capacitors or the like can also be used.

The topology according to 1 be used. A redundant energy supply for the safety-relevant consumers 16 can be provided both from the energy storage device 12 and via the so-called terminal KL 30_0 (input of the electronic load distributor 18 or output of the DC/DC converter 22 on the low-voltage vehicle electrical system side) and by the DC/DC converter 22, fed by the additional energy storage device 24 , take place. The redundancy from the supply via the so-called terminal 30_0 can only be ensured if the terminal 30_0 consumer power of the other consumers 9 is below a certain threshold. Otherwise, the supply of the terminal 30_1 or the terminal 30_1 loads from the DC-DC converter 22, possibly including dynamic load maneuvers (braking/steering maneuvers to switch to the safe state in automated driving), cannot be implemented and an impermissible voltage drop would occur, which could lead to the loss of function of the safety-relevant consumers 16 (steering, brakes,...).

The flow chart according to 2 shows a possible method for implementing the monitoring of consumers 9. It is advisable to carry out the method described later, ie after the vehicle has been switched off, so that the user does not notice any voltage-dependent degradation of consumers 9.

The vehicle is switched off. The DC-DC converter 22 remains active, as does the at least one consumer 9 to be monitored, step 101. Both preferably remain active until the monitoring has ended.

Separating means 19, for example a semiconductor switch, separates the two terminals KL 30 0 and KL 30_1 of electronic load distributor 18 from one another, step 102. This means that the voltage at KL 30_0 or at consumers 9 can no longer be supported by energy store 12. This allows the voltage-dependent degradation the consumer 9 are tested. In step 102 the loads 9 are therefore disconnected from the energy store 12 .

An energy management system (EEM) requests a specific power consumption Pmax, in particular a maximum power consumption, of the consumer(s) 9, step 103. Accordingly, the consumers 9 controlled in this way are ramped up to the desired power level, for example the full power consumption.

The power consumption of consumers 9 is measured, in particular by DC-DC converter 22, step 104. This is done under normal conditions or in the normal voltage range, for example U1 >= 12 V.

The voltage U1 is then regulated below a limit voltage Ug or degradation threshold of the relevant loads 9, in particular by the DC-DC converter 22, step 105. At the limit voltage Ug (for example Ug<9 V), the respective loads 9 are degraded in normal operation, to ensure voltage support of consumers 16 in the event of a fault in energy store 12. The limit voltage Ug is significantly below the voltage U1 in normal operation (U1 (normal operation) for example around 12 V).

If the voltage U1 falls below the limit voltage Ug, the relevant consumers 9 should (with proper operation) degrade themselves when the voltage falls below this, step 106.

A new measurement is then carried out, in particular using the DC-DC converter 22, to check whether the corresponding consumers 9 have actually been degraded, step 107. For this purpose, the DC-DC converter 22 can, for example, record the current consumption of the consumers 9. Based on the power consumption in step 106 compared to the power consumption in step 104, the DC-DC converter 22 or another evaluation means such as the energy management system can identify whether the relevant consumers 9 have carried out a proper degradation. Optionally, the DC-DC converter 22 or another component can detect a rate of degradation of the consumer(s) 9 via a suitable evaluation of the current measurement or the associated current gradient.

If the DC-DC converter 22 or another evaluation unit recognizes that the degradation of the consumers 9 is no longer sufficient or has fallen below the required level, a certain reaction follows according to a safety concept, step 109. In the event that the degradation of the consumers 9 is no longer sufficient is closed, for example, if the power consumption of the corresponding loads 9, as detected in step 107, does not fall below a specific value Ig, in particular within a specific time period. Alternatively, conclusions can also be drawn about the ability of consumers 9 to be degraded by evaluating the current gradient of consumers 9 . Appropriate warnings, demotion or deactivation of certain functions, error entries or the like can take place in step 109 .

If it can be concluded in step 107 that consumers 9 have been properly degraded, step 108 follows. If the ability to degrade consumers 9 is given, the functions can be continued as before in normal operation.

An evaluation of the diagnosis described could also be carried out in the electronic load distributor 18, for example. For this purpose, the measured values of the DC voltage converter 22 can be made available to it via appropriate communication means such as a bus system, in particular a CAN bus. Alternatively, the evaluation could also take place in other control units, such as in energy management, if the appropriate signal connection is provided.

The method is particularly suitable for ensuring the energy supply of safety-relevant consumers 16 in a motor vehicle that implement functions for automated driving. However, the use is not restricted to this.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2019/145087 A1 [0002]

Claims (10)

Method for monitoring the energy supply of a motor vehicle, in particular with an automated driving function, at least one energy store (12) being provided, which supplies at least one safety-relevant consumer (16), at least one electronic load distributor (18) being provided, via which the consumer (16 ) is controlled and secured, with the energy storage device (12) being connected to the load distributor (18), with an alternative supply of the safety-relevant consumer (16) being a DC-DC converter (22) which can be supplied from another energy storage device (24) with the electronic load distributor ( 18) is connected, and at least one further consumer (9) is supplied with energy between the DC-DC converter (22) and the electronic load distributor (18), characterized in that a voltage (U1) supplying the further consumer (9) is set to a Limit voltage (Ug) is lowered, in which a degradation, esp If the power consumption of the additional consumer (9) is switched off or reduced (step 105), an electrical parameter (I) of the additional consumer (9) is detected and based on the electrical parameter (I) a proper or incorrect degradation of the further Consumer (9) is closed. procedure after claim 1 , characterized in that the DC-DC converter (22) and/or the additional consumer (9) is separated from the energy store (12) (step 102), in particular before the voltage (U1) is reduced to the limit voltage (Ug). Method according to one of the preceding claims, characterized in that the further consumer (9) is ramped up to a certain power consumption (Pmax), particularly preferably maximum power consumption (Pmax) (step 103), in particular after the DC-DC converter (22) and/or the additional consumer (9) was separated from the energy store (12). Method according to one of the preceding claims, characterized in that an electrical parameter of the further consumer (9) is detected (step 104) when the further consumer (9) has been ramped up to a specific power consumption (Pmax) and/or after the voltage ( U1) has been lowered to the limit voltage (Ug) and/or the further consumer (9) has been degraded. Method according to one of the preceding claims, characterized in that the electrical parameter is detected by the DC voltage converter (22). Method according to one of the preceding claims , characterized in that at least one separating means (19) is provided in the electronic load distributor (18), which to ensure the electrical supply of the safety-relevant consumer (16) connects the DC voltage converter (22) to the safety-relevant consumer (16). connects. Method according to one of the preceding claims, characterized in that the parameter determined at the DC-DC converter (22) and/or at the electronic load distributor (18) and/or at the further consumer (9), in particular current and/or voltage, the electronic load distributor ( 18) and/or an energy management system or another control unit. Method according to one of the preceding claims, characterized in that a countermeasure such as transferring the vehicle to a safe state and/or activating a warning notice or a warning display and/or setting an error entry takes place if an incorrect degradation of the further consumer (9th ) is closed. Method according to one of the preceding claims, characterized in that a switching means (15), in particular a semiconductor switch, is used in the electronic load distributor (18) to control and protect the safety-relevant load (16), and certain parameters such as current, voltage are used for protection , temperature or the like are recorded and the safety-relevant consumer (16) is switched off when impermissible limit values are exceeded. Method according to one of the preceding claims, characterized in that the reduction of the voltage (U1 to the limit voltage (Ug)) and / or the aforementioned steps (102, 103, 104, 105, 106, 107, 108, 109) in one Monitoring operation that deviates from normal operation takes place/takes place.

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