DE102020109948A1 - Motor vehicle electrical system and electronic fuse for a motor vehicle electrical system - Google Patents

Abstract

The invention relates to a motor vehicle on-board network with electrical power sources (1) and electrical consumers (3), the power sources (1) and the consumers (3) being connected to other components of the motor vehicle on-board network via at least one overcurrent protection device (6) each electronic fuse (6) is.

Description

The invention relates to a motor vehicle on-board network with electrical power sources and electrical consumers, the power sources and the consumers being connected to other components of the motor vehicle on-board network via at least one overcurrent protection device each.

Overcurrent protection devices protect circuits from impermissibly high currents. These overcurrents can be caused by overload, short circuits, excessive power consumption by various consumers or other errors. In vehicle electrical systems, fuses are provided in fuse boxes as overcurrent protection devices, in which the integrated metal strip melts in the event of an overcurrent and thus interrupts the flow of current in the consumer circuit. The most common type of fuse is the blade fuse. After a fuse has melted, the fuse whose metal strip has melted must be replaced by a fuse with the correct rated current. The fuse is therefore not maintenance-free and is subject to mechanical wear. If the error recurs, the fuses must be replaced again and again, which means an increase in costs, effort and materials.

Furthermore, the fuses used are subject to aging and must be protected from contamination and corrosion. As a result of the aging process, it may also be necessary to replace the fuse.

In addition, individual circuits cannot be switched off quickly in a targeted manner at a safety-critical moment, since the fuse would have to be pulled out of the fuse box by hand.

This is where the present invention begins.

The present invention is based on the problem of improving a motor vehicle electrical system in such a way that the overcurrent fuses can be used more effectively.

This object is achieved according to the invention in that the overcurrent protection device is an electronic fuse.

Advantageous further developments of the invention are each the subject matter of the dependent claims.

The mechanical fuses are therefore replaced by electronic fuses according to the invention. This allows the maintenance effort to be reduced, since the electronic fuse means that the mechanical fuse does not need to be exchanged. Another advantage is that a short overcurrent does not trigger the overcurrent protection device, which can only be eliminated by replacing the overcurrent protection device. One property of the electronic fuses is that they can be switched on again after the overcurrent has ceased. On the other hand, the individually protected and possibly safety-critical components can be switched off in a targeted manner, for example in the event of an accident. In the event of an accident, it may make sense to switch off the seat heating in order to reduce the risk of a fire if the seat heating continues to be used, which could possibly arise if, as a result of the accident, a highly flammable liquid comes into contact with one of the heated seats Surface or come into contact with the seat heating itself.

According to the invention it is possible for some of the electronic fuses or all of the electronic fuses to be integrated circuits.

The term “at least some” used in the following can be understood as “at least one”, “at least a part” or “several” as well as “some or all”.

At least some of the electronic fuses can have an interface at which a status signal can be provided which represents the status of the fuse. The status of the electronic fuse can be queried via this interface. The status can then be analyzed, for example, in a processing means for handling errors. It is also possible to display the status by means of a display means. An electronic fuse can also have means for analyzing errors, with which an error causing the overcurrent can be analyzed and displayed at the interface.

At least some of the electronic fuses can have an interface to which a control signal can be applied in order to use the fuses to electrically connect the power sources or the loads to the other components of the motor vehicle electrical system or to disconnect them from the other components of the motor vehicle electrical system. The fuse can also be activated via this interface without an overcurrent being present, in order to separate the protected components from the rest of the vehicle electrical system. This can be useful, for example, if the protected component, i.e. the power source or the consumer, has a fault that is not noticeable as an overcurrent, but with a further current in or out of the protected one Components could damage or destroy the component or other parts of the motor vehicle electrical system or the motor vehicle.

The electronic fuse can have a CAN interface and be connected to a CAN bus, via which the fuse can receive control instructions for switching it on or off or can display the status or the result of an error analysis. A processing means which can process the status or the result of the error analysis can be connected to the CAN bus.

Mechanical fuses of motor vehicles are interconnected in conventional motor vehicle electrical systems in one or more fuse boxes. With more comfort systems and security systems in the vehicle, the car is becoming more and more electrified. This increases the number of components that need to be protected, including the number of backups and the size of the backups. In order to counteract the latter, in some vehicle electrical systems or in sub-networks of vehicle electrical systems, the electrical system voltage was increased to 48 V in order to reduce the currents and thus the cross-section of the lines but also the size of the fuses while maintaining the same output. Nevertheless, more and more space has to be found for fuse boxes as the number of fuses is increasing in today's vehicles. The fuse boxes, in which this large number of fuses can be installed, require space and must be installed in places that are easily accessible in order to be able to replace the fuse quickly. These locations are sometimes a long way from the secured component. As a result, the effort for cabling is increasing in the motor vehicles. The use of electronic fuses enables some of the electronic fuses to be integral parts of the power sources and / or loads. Because it is no longer necessary to replace the fuse with an electronic fuse after an overcurrent has occurred, the fuse can be installed in a decentralized manner, for example in the component to be protected itself or in a control unit of the component to be protected. It is also possible that at least some of the electronic fuses are used in electrical connection lines from or to the power sources and / or consumers. This can be the case in the immediate vicinity of the component to be protected. Even if the advantages of using an electronic fuse are not fully used, electronic fuses can also be arranged in fuse boxes of a motor vehicle.

An electronic fuse according to the invention for a motor vehicle electrical system according to the invention can have a comparator with which the electrical current flowing from or to the power source and / or from or to the consumer can be compared with a reference value in order to determine the overcurrent case.

An electronic fuse according to the invention can have a switch-on and switch-off circuit. The output of the comparator can be connected to the switch-on and switch-off circuit, with which the electric current flowing from or to the current source and / or from or to the consumer between an input and an output of the electronic fuse can be switched on or off if there is no overcurrent has been captured.

The switch-on and switch-off circuit of an electronic fuse according to the invention can comprise a flash memory or an RS flip-flop or another circuit with which a self-holding can be implemented in order to immediately, uncontrolled To prevent the power from being turned on again. The on and off circuit can have a controllable switch which is inserted into the line between the input and the output of the electronic fuse, a control connection to the flash memory, the RS flip-flop or at least one other element for implementation the self-holding is connected.

• 1 in schematischer Darstellung ein Kraftfahrzeug und ein Kraftfahrzeugbornetz nach dem Stand der Technik,
• 2 in schematischer Darstellung ein erfindungsgemäßes Kraftfahrzeug und ein erfindungsgemäßes Kraftfahrzeugbordnetz und
• 3 eine beispielhafte elektronische Sicherung.

The invention is explained in more detail below with reference to the accompanying drawings. It shows:

• 1 a schematic representation of a motor vehicle and a motor vehicle cradle network according to the state of the art,
• 2 a schematic representation of a motor vehicle according to the invention and a motor vehicle electrical system according to the invention and
• 3 an exemplary electronic fuse.

That in the 1 The vehicle electrical system shown has a battery as a power source and several consumers 3 on. The battery 1 is via electrical wiring 4a with fuse boxes or with those in the fuse boxes 2 arranged fuses connected. Further electrical lines lead from the fuses to the consumers 3 . In the event of an overcurrent in one of the lines 4th , 4a from the battery 1 to the consumer 3 melts the to hedge on these lines 4th , 4a connected consumer used fuse, reducing the electricity is switched off. The fuse must be replaced before the consumer can be restarted.

In the case of a possible vehicle electrical system, each consumer has 3 an electronic fuse 6th on that via lines 4th with the battery 1 , i.e. the power source, are connected. Fuse boxes and fuses are not provided. The electronic fuses 6th can determine the overcurrent case and the current to the protected consumer 3 turn off so that the secured consumer 3 leading line is no longer loaded with electricity. As a direct link between consumers 3 and the battery 1 exists that does not require the detour via a fuse box, a motor vehicle electrical system can be with fewer lines 4th manage as a motor vehicle electrical system with conventional fuses that are housed in central fuse boxes.

The one in the 3 electronic fuse shown 3 directs you to a battery 1 connected input E. and an output connected to a protected consumer A. on. Between the entrance E. and the exit A. are a shunt resistor R4 and MOSFET T1 arranged through which a current can flow to supply the consumer. The shunt resistance R4 is part of a comparator circuit that, in addition to the shunt resistor R4 an operational amplifier as a comparator and a voltage divider made of resistors R1 and R2 having.

The resistances R1 and R2 are between the entrance E. the electronic fuse and a ground connection. And that is the resistance R1 , which is an adjustable resistor, connected to the input and to the inverting input of the comparator. The resistance R2 is to the ground connection and the inverting input of the comparator and thus also to the resistor R1 tied together. Above the voltage divider R1 , R2 the vehicle electrical system voltage drops that of the battery 1 is specified. The voltage at the input of the inverting input of the comparator can be changed by changing the resistance R1 can be set.

The non-inverting input of the comparator is with a node between the shunt resistor R4 and the MOSFET T1 tied together. The voltage across the shunt resistor can be measured by the comparator R4 with that through the resistance R1 set voltage can be compared. The voltage across the shunt resistor is representative of the current through the shunt resistor R4 the one via the MOSTFET T1 flows to the protected consumer. As soon as the voltage across the shunt resistor R4 is greater than the reference voltage across the resistor R1 according to the settings, there is an overcurrent which is caused by the MOSFET T1 must be turned off.

The output of the comparator is to a gate of a MOSFET T2 tied together. Its drain is connected to the input of the electronic fuse. The source is at the base of a flash memory cell Flash connected and also via a drain-source path of a MOSTFET T4 connected to a ground connection.

A collector of the flash memory cell Flash is about a resistance R3 with the receipt of the electronic fuse 3 and with a gate of the MOSTFET T1 tied together. An emitter of the flash memory cell Flash is connected to a ground connection. Flows through the collector-emitter path of the flash memory cell Flash a current, becomes the gate of the MOSFET T1 pulled to ground potential, creating a current through the source-drain path of the MOSFET T1 is interrupted.

With the output of the comparator, the MOSFET T2 switched to the flash memory cell Flash programmed. This is non-volatile storage without energy consumption at the same time (Flash EEPROM). The flash memory cell Flash pulls the voltage on the gate of the MOSFET T1 to 0 V and opens the circuit to the consumer.

Opening the circuit breaks the signal from the comparator to the MOSFET T2 together, which in turn causes the signal from the flash memory cell Flash ceases to exist. As the flash memory cell Flash belongs to the non-volatile memory, this continues to pull the potential to 0 V and the MOSFET T1 remains open.

In parallel with the MOSFET T2 is a MOSTFET T3 switched with which the MOSFET T2 in a case where there is no overcurrent on the shunt resistor R4 present, can be bridged. A gate of the MOSFET T3 is with an entrance " occupy “Connected to the MOSFET by an external signal T3 can be controlled to close, which leads to the flash memory cell Flash is programmed. The flash memory cell Flash pulls the voltage on the adjacent MOSFET T1 to 0 V and opens the circuit to the consumer.

The drain of the MOSFET T4 is to the source of the MOSFET T2 , T3 and the base of the flash memory cell Flash tied together. The source of the MOSFET T4 is connected to a ground terminal and the gate of the MOSFET T4 with an entrance " Clear “Of electronic security. Is via the entrance " Clear “A signal to the MOSFET T4 the MSOFET is applied T4 closed and thereby the potential at the base of the flash memory cell Flash lowered. This leads to a change in the programming of the memory cell, which leads to an interruption of the current via the collector-emitter path of the flash memory cell Flash leads. This increases the potential at the gate of the MOSFET T1 raised and the mosfet T1 closes, removing the power from the battery 1 over the entrance E. , the shunt resistance R4 , the MOSFET T1 and the exit A. can flow to the consumer. The MOSFET can "delete" via the input T4 be controlled, for example, to the flash memory cell Flash to Clear . This means that the circuit can be switched on again maintenance-free without replacing a mechanical component

In addition, via a status signal connection info for example from a control unit 7th an info signal the status of T1 and thus the electronic security can be queried. The connection info is connected to the gate of the transistor for this purpose.

In principle, in addition to self-holding by means of a flash memory cell, all alternative methods of self-holding are also possible, e.g. bistable multivibrator, in particular an RS flip-flop. A flash memory cell has the advantage that the state can be reliably maintained over a long period of time.

List of reference symbols

1

battery

2

Safety box with mechanical fuses

3

consumer

4, 4a

cables

6th

electronic fuse

7th

Control unit

R1

Resistor for setting a reference voltage

R2

resistance

R3

resistance

R4

Shunt resistance

T1

MOSFET

T2

MOSFET

T3

MOSFET

T4

MOSFET

Comparator

Operational amplifier

Flash

Flash memory cell

E.

Electronic fuse input

A.

Electronic fuse output

info

Status signal connection

occupy

Input for opening the electronic fuse

Clear

Output to close the electronic fuse

Claims (10)

Motor vehicle on-board network with electrical power sources (1) and electrical consumers (3), wherein the power sources (1) and the consumers (3) are each connected to other components of the motor vehicle on-board network via at least one overcurrent protection device (6), characterized in that the overcurrent protection device is an electronic Fuse (6) is. Motor vehicle electrical system according to Claim 1 , characterized in that one or more of the electronic fuses (6) are integrated circuits. Motor vehicle electrical system according to Claim 1 or 2 , characterized in that one or more of the electronic fuses (6) is an integral part of the power source (1) and / or consumer (3). Motor vehicle electrical system according to one of the Claims 1 until 3 , characterized in that one or more of the electronic fuses (6) are used in electrical connection lines (4) from or to the power sources (1) and / or consumers (3). Motor vehicle electrical system according to one of the Claims 1 until 4th , characterized in that one or more of the electronic fuses (6) have an interface (info) at which a status signal can be provided which represents the status of the electronic fuse (6). Motor vehicle electrical system according to one of the Claims 1 until 5 , characterized in that one or more of the electronic fuses (6) have an interface (occupy, delete) to which a control signal can be applied in order to electrically power the power sources (1) or the loads (3) by means of the electronic fuses (6) to connect to the other components of the motor vehicle electrical system or to separate them from the other components of the motor vehicle electrical system. Motor vehicle with a motor vehicle electrical system according to one of the Claims 1 , 2 or 4th until 6th , characterized in that the at least one electronic fuse is arranged in one or more fuse boxes of the motor vehicle. Electronic fuse for a motor vehicle electrical system according to one of the Claims 1 until 6th , characterized in that the electronic fuse (6) has a comparator with which the electrical current flowing from or to the power source (1) and / or from or to the consumer (3) can be compared with a reference value. Electronic fuse after Claim 8 , characterized in that the electronic fuse (6) has a switch-on and switch-off circuit, and that the output of the comparator is connected to the switch-on and switch-off circuit (R3, Flash, T2, T1) to which the from or to the power source is connected (1) and / or from or to the consumer (3) between an input (E) and an output (A) of the electronic fuse (6) electrical current flowing can be switched on or off. Electronic fuse after Claim 9 , characterized in that the switch-on and switch-off circuit (R3, Flash, T2, T1) comprises a flash memory (Flash) or an RS flip-flop or is another circuit with which a self-holding can be implemented, the on - and switch-off circuit (R3, Flash, T2, T1) has a controllable switch (T1) which is inserted into the line between the input (E) and the output (A) of the electronic fuse (3), a control connection with the Flash memory (Flash), the RS flip-flop or at least one other element for realizing the self-holding is connected.

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