DE102018201546A1 - Device for securing at least one consumer - Google Patents

Abstract

The invention relates to a device for securing at least one load in a vehicle electrical system, in particular a motor vehicle, comprising at least one switching means (32) for supplying at least one load (22, 26, 28, 46) with electrical energy, at least one controller (30) Control of the switching means (32), at least detecting means for detecting characteristics, in particular current and / or voltage, the controller (30) depending on the characteristic the switching means (32) controls, wherein at least one overvoltage protection (39) is provided.

Description

The invention relates to a device for securing at least one consumer according to the preamble of the independent claim.

State of the art

From the EP 1453171 A1 is known an electronic protection circuit.
Serving as a protective element MOSFET circuit breaker uses to protect the power supply input operating in reverse mode Mosfet with internal inverse diode, with its drain-source path in the reverse direction between the protected supply voltage input or to be protected input line relatively low voltage levels of the load regulator or control device and its internal, for example, a common relatively lower voltage for a plurality of electrical or electronic components supplying voltage supply rail is connected. In normal operation, this additional switch must carry the full operating current without having a function in normal operation.

It is an object of the present invention to further simplify a protection circuit, in particular against overvoltages. This object is solved by the features of the independent claim.

Disclosure of the invention

The provision of overvoltage protection in the electronic power distributor has the advantage that, on the one hand, the switching means provided in the electronic power distributor are reliably protected against overvoltages without the need for a special blocking capability in the case of semiconductor switches. The suitable arrangement of the overvoltage protection, in particular at the output of the consumer, is used to easily absorb the energy without the need to provide particularly complex components. The proposed overvoltage protection makes it possible to isolate overvoltages from critical vehicle electrical system paths or to derive such overvoltages. This is particularly important for safety-critical consumers who are needed in connection with automatic driving functions, for example, to carry out an emergency stop or the like, in order to further increase the availability of these functions. In addition, especially in connection with the increasing electrification of ancillary components and mechatronic systems, recuperative loads are increasing, so that more overvoltages can occur. Furthermore, the proposed concept on the other hand, an electronic security function remain guaranteed, the consumer and corresponding leads safely protects against critical operating situations, as can be achieved by rapid shutdown with semiconductor switches as a possible switching means.

In an expedient development of the overvoltage protection is arranged so that it keeps away from the consumer caused overvoltages from the switching means. For this purpose, the overvoltage protection is particularly preferably connected between the output and a reference potential, in particular ground. Particularly preferably, the overvoltage protection has at least one discharge path which, in particular, diverts a current flowing back through the output before reaching the switching means to ground. As a result, in particular, a current flow via an inverse diode of the switching means designed as a semiconductor switch is prevented by the further switching means of the overvoltage protection being closed. The recuperation energy can be distributed over the ohmic losses in the source, the line resistance in the wiring harness and the resistance in the other switching means. Due to the usually high copper resistance in the consumer, a large part of the power loss is already implemented in the consumer. As a result, only a small part of the energy must be carried by the further switching means, which is why this arrangement is particularly suitable.

In an expedient development of the overvoltage protection comprises at least one surge arrester and / or an overvoltage element, which is preferably connected in series with the further switching means. As a result, particularly high energies can be absorbed, which might not be possible with semiconductor switches alone. Particularly expedient, the overvoltage element is designed as a resistive element or resistive resistor, preferably meander-shaped. As a result, a large amount of energy in the circuit structure can be stored or reduced. In addition, an additional channel could be used to load a current for diagnostic purposes of the vehicle electrical system as a load.

In an expedient development, at least one capacitor and / or at least one diode, preferably a suppressor diode and / or at least one varistor and / or at least one gas discharge path is provided as the surge arrester. This high energy or performance can be absorbed using simple components.

In an expedient development of the surge arrester is connected in series with at least one other switching means and in parallel this at least a third switching means. This allows corresponding elements only switch on when needed, which negative influences can be reduced by, for example, rough tolerances or high cross currents.

In an expedient development, the controller activates the further switching means and / or the third switching means in a staggered and / or timed manner. Thus, the connected consumer still sufficient time can be given to prepare for the shutdown.

In an expedient development, at least one capacitor is connected to an input of the electronic power distributor and / or connected to a mass output. As a result, the protection against overvoltages, such as might be caused by Induktivitätsbelägen in lines can be improved. A bypass can be created via this path to reduce overvoltages.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

list of figures

Show it

• 1 a schematic representation of a vehicle electrical system with integrated safety device,
• 2 a more detailed view of a first embodiment of a safety device with switchable Ableitpfad at the output to the load,
• 3 a schematic representation of a multi-voltage vehicle electrical system with two integrated safety devices,
• 4 Another embodiment of a safety device with additional surge arrester,
• 5 a further embodiment of a securing device, which compared to that of 4 is extended by another switching means,
• 6 a circuit of a further embodiment of a safety device, which is particularly suitable for reverse polarity protection required,
• 7 a schematic representation of an overvoltage diverting element, which is meander-shaped designed as a resistive consumer, as well as
• 8th a schematic representation to illustrate the operation of the safety device in a surge risk by originating from cables Induktivitätsbelegen.

Embodiments of the invention

In a wiring system 10 are exemplary at least one energy storage 16 as well as a safety-critical consumer 18 each switched to ground. In this electrical system 10 it is a sensitive on-board electrical system, as it is safety-critical consumers 18 includes, which must be protected against overvoltage especially safe. This is an electronic energy distributor 20 provided that another consumer 28 and the associated lines in the form of an electronic fuse protects and controls. This is in the electronic power distributor 20 at least one detection means 50 to capture at least one supply to the consumer 22 . 26 . 28 . 46 relevant characteristic, in particular for the detection and evaluation of the flowing currents or voltages provided. As a means of detection 50 can corresponding voltage divider to attack the input voltage and / or the output voltage at the electronic power distributor 20 be provided and / or corresponding measuring devices of the flowing input current and / or output current. The required parameters are fed to a controller in which the corresponding evaluations can be made. If an excessively high current flows or threatens an unacceptable load situation, then the electronic power distributor conducts 20 appropriate countermeasures. For this purpose, for example, a switching means 32 provided, which is the consumer 28 from the electrical system 10 separates. Accordingly, the electronic power distributor 20 at least one entrance 34 on, via the electronic power distributor from the electrical system 10 is energized. In addition, the electronic power distributor points 20 at least one switchable output 36 on that with the associated consumer 28 connected is. In practice, the electronic power distributor 20 a lot of other outputs 36 each with consumers to be protected 28 via appropriate switching means 32 disconnected are connected.

These are in the controller 30 corresponding evaluation functions deposited. In particular, will the load current as a possible parameter for the supply of the consumer 22 . 26 . 28 . 46 evaluated by a backup functionality and compared with at least one predetermined Abschaltekriterium a parameter set. The controller 30 triggers a triggering process, causing the electronic fuse (in the form of switching means 32 ) and shuts off the load current to the corresponding load when the predetermined switch-off criterion is met. The controller 30 is set up to record and evaluate load currents of several electronic fuses or switching devices to the various consumers. Appropriate detection means 50 for recording for the supply of the consumer 22 . 26 . 28 . 46 relevant parameters are provided. A shutdown can individually for each of the electronic fuses or switching means 32 respectively. This described functionality is essential for the electronic power distributor 20 . 24 , Furthermore, the controller can 30 be able to, depending on the requirements of higher-level control devices consumers 22 . 26 . 28 . 46 in normal operation to activate or deactivate. For this the controller points 30 not specifically illustrated signal terminals to communicate, for example via a bus system with other control devices, especially in the vehicle. In addition, the controller can 30 or the electronic energy distributor 20 . 24 as a further communication option have a diagnostic connection.

To clarify the additional function of the electronic power distributor 20 . 24 It is believed that it is the consumer 28 in some circumstances the on-board network 10 disturbing consumer acts. In the embodiment according to 1 may be the disturbing consumer 28 in case of errors by the switching means 32 from the sensitive electrical system (such a vehicle electrical system branch 10 , in particular a safety-critical consumer 18 includes) unidirectionally separated. In order to realize the required speed at the shutdown, usually semiconductor switches are used as switching means 32 used, which have a maximum permissible reverse voltage combined with a maximum allowable energy intake above this reverse voltage. Especially in connection with recuperative consumers 28 such as generators that return a braking energy back to the electrical system 10 feed, temporarily high surges can occur. Just such consumers 28 By induction, they can generate very high voltages, which are above the blocking capability of simple, less expensive semiconductors, which are used for protection in the electronic energy distributor 20 . 24 to be used. These induced voltages can often have an energy content in the range of several joules due to the mechanical energy from which they are generated. The aim now is a security device in particular as part of the electronic power distributor 20 . 24 specify which of these energies absorbs reliably and without resorting to particularly expensive semiconductors. This should be overvoltages caused by consumers 28 and / or Leitungsinduktivitäten (Induktivitätsbelägen 68 ) can be generated isolated from critical electrical system paths or surges are derived.

In the embodiment according to 2 is the electronic energy distributor 20 . 24 shown in more detail, which also has a surge protection 39 was extended. Between the entrance 34 and the exit 36 is the switching means in the current path 32 , The switching means 32 is from the controller 30 driven. The controller 30 Relevant measured variables such as the input voltage and / or the output voltage and / or the input current and / or the output current or the like, possibly tapped via corresponding voltage divider supplied. The controller 30 determines control commands for the switching means from the measured variables and, if appropriate, further information 32 , This is how the switching device works 32 open, for example, if too high loads are expected, the consumer 46 and / or damage its supply.

To protect especially against overvoltages is part of the overvoltage protection 39 another switching means 40 intended. The further switching means 40 is between the switching means 32 and the exit 36 on the one hand and against ground (via a mass output 38 ) on the other hand switched. The further switching means 40 is controlled by the controller, for example 30 , By this arrangement, a switchable Ableitpfad 48 at which the overvoltage inducing current, as indicated by an arrow, is derived at the output 36 or at the output to the load 46 realized. With an excessive current consumption by the consumer 46 this can be done by opening the switching means 32 fast from the electrical system 10 be separated. Now, for example, an excessive recuperation of this consumer 46 in the electrical system 10 , so too is the switching means 32 open. In the switching means 32 it can preferably be a power semiconductor, for example a field effect transistor with inverse diode or MOSFET. To a current flow through this inverse diode of the switching means 32 to prevent, is now the other switching means 40 closed. The Rekuperationsstrom is through the other switching means 40 shorted. The absorbed recuperation energy is distributed along the discharge path 48 (along which the recuperation flows as indicated by an arrow) while the ohmic losses in the source 46 as with the internal resistance 44 indicated a line resistance 42 in the wiring harness and the resistance in the other switching means 40 , In the further switching means 40 it could also be a semiconductor switch like a Mosfet again 2 indicated act. The ohmic loss at the other switching means 40 is implemented on the resistor Rds, so the resistance in the path between the drain and source of a mosfet. Due to the usually high copper resistance 44 of the consumer 46 Much of the power loss in this consumer 46 implemented. Only a small part of the energy must be from the other switching means 40 be worn.

According to 3 a multi-voltage vehicle electrical system is provided, wherein a first sub-board network 10 with a first tension U1 operated by, for example, 12V. Another sub-board network 12 has another tension U2 on, which is higher than the first voltage U1 , The further tension U2 is for example in the range of 48 V or higher. The two sub-networks 10 . 12 are through a DC-DC converter 14 coupled together. In the sub-board network 10 are exemplary a safety-critical consumer 18 as well as an energy storage 16 , each connected in parallel to ground, provided. Also, in the sub-board network 10 an electronic energy distributor 20 provided, the more consumers 22 exemplified only a single consumer 22 , with the supply voltage U1 can provide. Again, in the electronic energy distributor 20 the protection of management and / or consumers 22 realized as already described. In addition, measures are also taken to overvoltage protection as described in more detail below. In the further sub-board network 12 is another electronic energy distributor 24 provided that with the further tension U2 powered high-voltage consumers 26 controls and according to the described functionality of the electronic power distributor 20 . 24 safeguards. The further electronic energy distributor 24 could be able to do a lot of other consumers 26 accordingly to control and secure.

For cost reasons are in parts of the further sub-board network 12 (High voltage electrical system) as well as in the first sub-board network 10 (Low-voltage electrical system) in a common wiring set, which increases the risk of short circuits as indicated by an arrow. From the further sub-board network 12 In the event of a fault, a high current flows into the first onboard power supply 10 , Due to the high driving voltage U2 and the usually lower internal resistance of the (not shown) high voltage source, the current reaches values that are well above 1000 A and from the conventional 12 V battery (energy storage 16 ) can not be clamped. If instead of the electronic power distributor 20 . 24 Conventional fuses are installed, they trigger only after several milliseconds, if already high amounts of energy in the first electrical system 10 flowed. In the area of the low voltage on-board network 10 the fuses are not at the higher voltage U2 designed and possibly unable to interrupt the flow of electricity. Thus flows in the case of a short circuit between the two Bordnetzzweigen 10 . 12 a very high current through among others the consumer 18 ,

At the in 3 described embodiment in a hedge over two in the different sub-networks 10 . 12 arranged electronic power distributors 20 . 24 do not become supply-critical consumers 22 . 26 over the output of the electronic power distributors 20 . 24 secured and monitored. In addition to the protection of the wiring harness, this protection includes monitoring for the current direction via a current sensor (for example integrated in the switching means) 32 ) in the electronic power distributor 20 of the first sub-board network 10 ,

Is a backward current flow above a limit from the consumer 18 back to the electrical system 10 detected, becomes the switching means 32 open and at the same time the other switching means 40 closed. The switching means 32 as well as the further switching means 40 are in electronic power distribution 20 arranged and controlled by the controller 30 driven. This will cause the flow of current within the electronic power distributor 20 derived and another current flow into the electrical system 10 prevented. By the direct conclusion to mass becomes over the further switching means 40 achieved a rapid increase in current of the short-circuit current, which leads to an automatic triggering of the quick shutdown in the other electronic power distributor 24 the further sub-board network 12 (High voltage network) leads and thus to open the switching means 32 ' the further electronic energy distribution 24 ,

Under certain circumstances, very high energies or services must be absorbed. This can be done with semiconductor designed as switching means 40 for the realization of overvoltage protection 39 alone may not be accomplished. For example, with certain consumers 46 could be the solution according to 2 or 3 too inadmissibly high braking torque by the consumer 46 to lead. To counteract this, according to the embodiments according to the 4 and 5 at least one surge arrester 52 as part of the overvoltage protection 39 intended. The surge arrester 52 is here between the switching means 32 and the further switching means 40 arranged. In the surge arrester 52 it is, for example, a varistor, a gas discharge path or a diode, preferably an overvoltage protection diode such as Suppressor diodes. Suppressor diodes are characterized in particular by a rectangular characteristics even at high currents and can absorb high energies. Suppressor diodes have the disadvantage of relatively rough tolerances. Varistors have the disadvantage of high cross currents. This can be counteracted by activating these components actively, ie only in case of a need in the circuit. If very high energies must be absorbed, one of the aforementioned surge arresters can also be used 52 to be overwhelmed. In this case, the approach according to 4 with that of the 2 be combined. This creates a circuit according to 5 ,

According to 5 is still a third switching means 54 as part of the overvoltage protection 39 intended. For example, the third switching means 54 to be connected in parallel to the series connection of further switching means 40 and surge arresters 52 , Also the third switching means 54 is controlled by the controller 30 , This could be staggered over time, for example to the connected consumer 28 still enough time to prepare for a shutdown. Depending on the internal structure of the connected consumer 28 are also clocked variants conceivable in which between the individual switching means 40 . 54 is switched several times. Also the third switching means 54 can be configured as a semiconductor switch, in particular as Mosfet.

The embodiment according to 6 is particularly suitable for facilities where a reverse polarity protection 56 is required. This is in the electronic power distributor 20 . 24 between the entrance 34 and the switching means 32 a polarity reversal switching means 56 arranged, in turn, by the controller 30 is controllable. Again, this is the other switching means 40 as part of the overvoltage protection 39 provided, to which an overvoltage diverting element 58 followed. Parallel to that from the other switching means 40 and the overvoltage diverter 58 formed branch can be a diode 60 be connected in parallel as freewheel as in 6 shown. The further switching means 40 is between the reverse polarity protection 56 and the switching means 32 connected and via the surge arrester 58 switched to ground.

The overvoltage element or overvoltage discharge element 58 is designed in this example as a resistive consumer. The preferably meander-shaped or areal constructed overvoltage element 58 serves to convert a possible Rekuperationsleistung in the circuit board surface in heat. Especially by the flat structure of the overvoltage element 58 can be a high amount of energy in the construction and connection technique of the electronic power distributor 20 . 24 , in particular in the PCB and the cooling bank, are stored. In addition, through this additional channel a power for diagnostic purposes of the electrical system 10 be impressed as a load.

The discharge path 48 in the embodiment according to 6 runs over the switching means 32 (or its inverse diode), the closed further switching means 40 , the overvoltage element 58 to the mass output 38 , Via this discharge path 48 the current flows away.

In the embodiment according to 7 are different embodiments of the overvoltage element 58 . 58 ' . 58 " shown. In one embodiment, the meanders of the overvoltage element form 58 ' transverse, in the other embodiment form the meander of the overvoltage element 58 " along to the between the contact points extending conductor track direction.

In addition to the described scenarios in which an overvoltage in the recuperation of a consumer 46 can be generated, an overvoltage also due to Induktivitätsbelägen 68 arise in the pipes. In the embodiment according to 8th are the inductance pads 68 both at the entrance 34 , at the exit 36 and at the mass output 38 located. In case of opening the switching means 32 , with simultaneous high current flow in the input / output line of the electronic power distributor 20 . 24 can a high amount of energy in the inductance coating 68 be stored in the wiring harness. This current flow leads to a voltage increase at the input 34 of the electronic power distributor 20 . 24 and can lead to dangerous surges for the electronic power distributor 20 . 24 and other consumers connected to additional channels 22 . 26 to lead. To minimize damage on the one hand, the amount of energy that is stored in the wiring harness is minimized. In order to minimize the overcurrent, which can occur, for example due to short circuits on the consumer side, compared to conventional fuse elements by approximately the factor 10 faster response to short circuits needed (<< 100 μs). There will also be another path 66 (so-called bypass path) between entrance 34 and mass output 38 intended. In this path 66 are another switching device 64 and a capacitor connected in series therewith 62 intended. The further switching means 64 is from the controller 30 driven. About this path 66 a bypass can be created to reduce overvoltages. Instead of an active clamping on the other switching means 64 could also be passive relief networks for the capacitor 62 be used. In the embodiment according to 8th is still the other switching means 40 as part of the overvoltage protection 39 between exit 36 and mass output 38 arranged as described earlier in more detail. The combination of a minimization of the stored energy by a fast error response and the provision of a damped capacitive energy storage (condenser 62 ), which preferably has to absorb only a small amount of energy, allows effective overvoltage protection at shutdown transients.

The presented device is particularly suitable for vehicles in which the electrical system 10 . 12 has a high safety relevance or security relevant consumers 18 fed. This is the case, for example, for vehicles with automated driving functions.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• EP 1453171 A1 [0002]

Claims (12)

Device for protecting at least one consumer in a vehicle electrical system, in particular of a motor vehicle, comprising at least one electronic power distributor (20, 24), which has at least one switching means (32) for supplying at least one electrical load (22, 26, 28) connected via an output (36) , 46), at least one controller (30) for controlling the switching means (32), at least one detecting means (50) for detecting at least one of the supply of the consumer (22, 26, 28, 46) relevant parameter and at least one input (34 ) for supplying the electronic power distributor (20,24) with electrical energy, wherein the controller (30) depending on the characteristic, the switching means (32) for protecting the consumer (22, 26, 28, 46) and / or its supply line against excessive loads, characterized in that the electronic power distributor (20, 24) in addition to the switching means (32) at least one Überspannun protection (39). Device according to one of the preceding claims, characterized in that the overvoltage protection (39) is arranged so that it by the consumer (22, 26, 28, 46) caused overvoltages of the switching means (32) keeps away. Device according to one of the preceding claims, characterized in that the overvoltage protection (39) is connected between the output (36) and a reference potential, in particular ground. Device according to one of the preceding claims, characterized in that the overvoltage protection (39) has at least one discharge path (48, 66) which discharges a current flowing back through the output (36) before reaching the switching means (32) in particular to ground. Device according to one of the preceding claims, characterized in that the overvoltage protection (39) comprises at least one further switching means (40, 54, 64). Device according to one of the preceding claims, characterized in that the further switching means (40, 54) is at the same potential as an output (36) to which the consumer to be controlled (22, 26, 28, 46) is connected, and / or that the further switching means (40, 54) is connected to a ground output (38). Device according to one of the preceding claims, characterized in that the overvoltage protection (39) comprises at least one surge arrester (52) and / or an overvoltage element (58), which is preferably connected in series with the further switching means (40). Device according to one of the preceding claims, characterized in that the overvoltage element (58) is designed as a resistive element or ohmic resistor, preferably meandering. Device according to one of the preceding claims, characterized in that at least as a surge arrester at least one capacitor (62) and / or at least one diode (52, 60), preferably a suppressor diode, and / or at least one varistor and / or at least one gas discharge path is provided. Device according to one of the preceding claims, characterized in that the surge arrester (52) is connected in series with the further switching means (40) and parallel thereto at least a third switching means (54) is connected. Device according to one of the preceding claims, characterized in that the controller (30) activates the further switching means (40) and the third switching means (54) staggered in time and / or clocked. Device according to one of the preceding claims, characterized in that at least one capacitor (62) with an input (34) of the electronic power distributor (20) is connected and / or connected to a ground output (38).

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