DE102015015461A1 - Device and method for switching a current in an electrical supply line and motor vehicle - Google Patents

Abstract

The invention relates to a device and a method for switching a current (I) in an electrical supply line (4) of a motor vehicle (1) as a function of a switching signal (20), wherein a two-pole switching device (12) having a first connection pole (10). and a second connection pole (11) is provided and a control device (17) sets a switching state (14) of the switching device (12) in response to a detection signal (S). The invention provides that one of the supply line (4) different electrical coupling device (19) at least one of the terminal poles (10, 11) with a ground potential (6) of the motor vehicle (1) coupled, wherein the coupling device (6) has a controllable connecting element (24) which receives the switching signal (20) and electrically connects the at least one connection pole (10, 11) to the ground potential (6) if the switching signal (20) is present, and the coupling device (19) comprises a detection device (26 ), which generates the detection signal (S) as a function of a mass flow (Ig) flowing through the coupling device (19) to the ground potential (6).

Description

The invention relates to a device for controlling a current in an electrical supply line, as may be provided in a motor vehicle. By controlling a current is meant switching on and / or interrupting the current in the supply line. The current is controlled in response to a switching signal. The device has a so-called two-pole switching device which can be connected in the supply line. For switching the switching device, a control device is provided. The invention also includes a motor vehicle with the device according to the invention and a method for controlling a current.

A device of the type described is for example from the EP 2 843 496 A1 known. Their switching device is realized by a field effect transistor (FET), which is switched by a control device coupled to the control input of the FET. The controller switches the FET in response to a signal from a microcontroller. This is supplied via a supply voltage which is present between a supply plus and the ground potential. For the control device to correctly convert the signal of the microcontroller into switching operations, the microcontroller and the control device must have the same reference potential. This can lead to difficulties when the supply voltage in the supply line fluctuates due to, for example, a large load current.

Also from the DE 11 2010 006 027 T5 a two-pole switching device for a power line or supply line is described, which can be switched by a microcontroller. The switching signal is also generated in relation to the ground potential, so that even here voltage fluctuations in the supply line can lead to the switching signal is not correctly interpreted or implemented.

From the DE 10 2008 064 393 A1 is a two-pole switching device is known in which a voltage drop across a fuse of an electrical supply line is determined, ie a potential difference that is independent of the ground potential. Based on this potential difference, a field effect transistor is connected in the supply line.

From the DE 10 2009 029 226 A1 It is known to provide for electrical isolation of a switching device on the one hand and the associated control device on the other hand, a magnetic coupling via a relay, through the armature of a resistor component between two normally-open contacts in the supply line is pressed.

From the DE 10 2009 000 593 A1 For this purpose, it is known to operate an electromechanical component for switching, for example a relay, pulsed.

From the DE 20 2013 104 052 U1 is a low-voltage double socket with built-in buck converter known. The buck converter is operated by pulse width modulation so that MOSFETs (metal-oxide semiconductor FET) of the buck converter are switched clocked.

The invention has for its object to reliably switch a two-pole switching device which is connected in an electrical supply line, even with voltage fluctuations or potential fluctuations of the supply line.

The object is solved by the subject matters of the independent claims. Advantageous developments of the invention are given by the features of the dependent claims.

The invention thus provides a device for controlling or switching a current in the electrical supply line as a function of a switching signal. The current is controlled by means of a two-pole switching device which has a first connection pole for connection to a source-side line part of the supply line and a second connection pole for connection to a consumer-side line part of the supply line. In other words, the switching device connects after connecting the two line parts. Thus, the line parts are connected via the switching device. If the switching device is in an electrically blocking state, no current can flow between the line parts and thus also no current in the supply line as a whole. If the switching device has an electrically conductive state, then the current between the line parts and thus the current in the supply line can flow overall. For setting the switching state, the switching device has a control input. A control device for setting the switching state of the switching device is coupled to this control input. The control device is set up to set the switching state as a function of a detection signal.

So that now the switching device and the control device can be reliably operated independently of potential fluctuations on the supply line, is a different electrical connection means from the supply line for coupling at least one of the connection poles of the two-pole switching device, that is, the source-side and / or the consumer-side connection pole, provided with a ground potential of the motor vehicle. The coupling device is in particular also different or different from the switching device itself. The coupling device can thus have a first line branch which connects the source-side first connection pole to the ground potential. Additionally or alternatively, a second line branch may be provided which connects the consumer-side second connection pole to the ground potential. The coupling device in this case has a switch or generally a switchable ausgestaltetes connecting element, which is adapted to receive the actual switching signal by which is controlled or determined whether the current should flow in the supply line or not. The connecting element is further configured to connect the at least one terminal pole to the ground potential only if the switching signal is present, that is, if the switching signal has an active level or high level.

The switching signal thus does not directly control the two-pole switching device of the supply line itself, but only the connecting element, which connects the first terminal pole and / or the second terminal pole to the ground potential as a function of the switching signal. If the connecting element is electrically conductive, that is to say the at least one connecting pole is connected to the ground potential, then an electric current flows from the connecting pole to the ground potential. This current is referred to here as ground current. The coupling device furthermore has a detection device which generates the detection signal as a function of the mass flow flowing through the coupling device to the ground potential. Thus, if the connection element is switched to be electrically conductive by the switching signal and thus a ground current is generated by the at least one connection pole towards the ground potential, this is detected by the detection device and signaled as a detection signal to the actual control device. The control device then switches in dependence on the detection signal, the two-pole switching device via the control input.

In this case, for detecting or detecting the mass flow, the detection device can detect a voltage drop across a resistance element, that is, a shunt resistor, so that the detection device has no dependence on the absolute potential.

The invention provides the advantage that when the connection element is open when no mass flow flows, the arrangement of two-pole switching device and control device and the coupling device can follow the potential of the supply line free. Furthermore, the coupling device is de-energized, so that no control current is needed to maintain the switching state of the switching device. Only to change the switching state, the connecting element must be closed, so that flows to trigger the state change of the switching device, the mass flow. Otherwise, no reference of the control device and the coupling device to the ground potential is necessary. Furthermore, a current flow of the ground current is always possible as long as the potential of the supply voltage is greater than the ground potential.

The invention also includes optional developments, by the characteristics of which additional benefits.

A further development provides that each of the connection poles is connected to the ground potential by the coupling device. This has the advantage that regardless of the current switching state of the switching device, the mass flow can be generated at any time.

A development provides that the coupling device has a diode whose flow direction is directed by the at least one terminal pole to the ground potential. As a result, the device is also upgraded to switch an alternating current. Another advantage is a reverse polarity protection.

A development provides that the detection device for each coupled to the ground potential terminal pole each comprises a current source which is adapted to set a current intensity of the ground potential of the terminal to ground potential flowing to a predetermined value. This results in the advantage that even with a closed or electrically conductive connecting element, the potential of the supply line remains independent of the ground potential.

A development provides that the control device for the two-pole switching device is set up to set the switching state of the switching device according to a predetermined pulse length coding as a function of a pulse duration of the detection signal. In other words, a rectangular pulse is generated as the detection signal. Depending on the pulse duration of the rectangular pulse, the control device switches the two-pole switching device either in an electrically conductive state or in an electrically blocking state. Pulse length coding has the advantage that it is very robust against false triggering. By selecting or assigning the switching states to the pulse duration of the detection signal, a priority can be placed on fast switching on or fast switching off.

In particular, a reference duration is predetermined by the pulse length coding, and the control device is set up to set a first switching state of the switching device (for example, electrically blocking) if the pulse duration of the detection signal is shorter than the reference duration. Furthermore, the control device is set up to set a second switching state of the switching device that is complementary to the first switching state (for example, electrically conductive) if the pulse duration of the detection signal is greater than the reference duration. By specifying a reference duration, there is the advantage that a comparison between a quick response or reaction time of the control device on the one hand and the robustness against false triggering by setting the reference duration is possible.

For switching the current, the switching device preferably has at least one semiconductor switch, in particular a FET, for example a MOSFET.

A further embodiment provides that the switching device is configured self-holding. It thus holds independently of the control device the last set switching state until the control device generates a switching signal. Thus, the switching device between the switching operations remain de-energized, which allows a particularly economical operation of the device. A self-holding switching device can, for. B. be realized by means of a FET with a gate capacitance. For the self-holding embodiment, for example, a flip-flop circuit may be provided.

The invention also includes a motor vehicle with a supply line for electrically connecting an electrical voltage source with at least one electrical load. For example, the supply line may be the electrical line for connecting the vehicle battery to the electrical consumers. The supply line may in particular be part of an electrical system of the motor vehicle. The supply line has two line parts, namely a source-side line part and a consumer-side line part. These two line parts are connected via an embodiment of the device according to the invention, so therefore, starting from the voltage source, the source-side line part leads to the device and, starting from the device, the consumer-side line part leads to the electrical consumers. The motor vehicle according to the invention has the advantage that no operating current is necessary to maintain the switching state of the switching device of the device according to the invention. Thus, in particular when the vehicle is switched off or parked, the vehicle battery is not loaded.

Finally, the invention also includes a method for switching a current in an electrical supply line of a motor vehicle as a function of a switching signal. The method assumes that a two-pole switching device is provided with a first connection pole for connection to a source-side line part of the supply line and a second connection pole for connection to a consumer-side line part of the supply line and with a control input. A control device coupled to the control input adjusts a switching state of the switching device as a function of a detection signal. In order to generate the detection signal, an electrical coupling device different from the supply line couples at least one of the connection poles to the ground potential of the motor vehicle, the coupling device having a controllable connection element which receives the actual, external switching signal and only electrically connects the at least one connection pole to the ground potential, if the switching signal is present. Otherwise, if so, the switching signal is not present, the potential of the supply line is disconnected from the ground potential. The coupling device has a detection device which generates the detection signal as a function of the mass flow flowing through the coupling device to the ground potential.

The inventive method thus results from the operation of the device according to the invention and thus leads to the same advantages.

The invention also includes developments of the method according to the invention, which have features as they have already been described in connection with the developments of the device according to the invention. For this reason, the corresponding developments of the method according to the invention are not described again here.

In the following an embodiment of the invention is described. This shows:

1 a schematic representation of an embodiment of the motor vehicle according to the invention and

2 a schematic representation of diagrams to illustrate a Pulse length coding for switching a switching device of the motor vehicle of 1 ,

The exemplary embodiment explained below is a preferred embodiment of the invention. In the exemplary embodiment, the described components of the embodiment each represent individual features of the invention that are to be considered independently of one another, which also each independently further develop the invention and thus also individually or in a different combination than the one shown as part of the invention. Furthermore, the described embodiment can also be supplemented by further features of the invention already described.

In the figures, functionally identical elements are each provided with the same reference numerals.

1 shows a motor vehicle 1 which may be, for example, a motor vehicle, in particular a passenger car. The car 1 has a voltage source 2 on, which is in particular the vehicle battery and / or an electric generator. The voltage source 2 generates a supply voltage 3 that have a supply line 4 to electrical consumers 5 of the motor vehicle 1 is transmitted. The electrical consumers 5 are in 1 represented by a single symbol. The electrical consumers 5 For example, an air conditioning device and / or an electric starter for an internal combustion engine and / or a lighting device of the motor vehicle 1 include.

The one from the voltage source 2 to the electrical consumers 5 flowing supply current or short current I is above a ground potential 6 of the motor vehicle back to the voltage source 2 routed so that the circuit closes. For switching or controlling the current I is a device 7 provided via which a source-side conduit part 8th the supply line 4 and a consumer-side line part 9 the supply line 4 interconnected with each other. For this purpose, the source-side line part 8th to a first terminal pole 10 and the consumer-side line part 9 to a second terminal pole 11 connected. The connecting poles 10 . 11 are via a switching device 12 interconnected or connected. This is the switching device 12 with the connection poles 10 . 11 a two-pole switching device. The supply current I thus flows through or via the switching device 12 ,

Overall, the device 7 a switching function or relay function, which also serves as a backup function to protect the consumer 5 can be extended against an overcurrent or too high a current of the supply current I.

To interrupt the supply current I is a semiconductor switch 13 or are multiple semiconductor switches 13 through the switching device 12 provided. The switching device 12 can be between two switching states 14 be switched, namely an electrically conductive switching state 15 (ON) and an electrically blocking state 16 (OFF). For switching between the switching states 14 is a control device 17 with a control input 18 the switching device 12 connected. The switching device 12 is designed to be self-holding, so that it is without a signal at the control input 18 the last set switching state 14 self-employed.

The control device 17 switches between the switching states 14 in response to a detection signal S to that of a coupling device 19 is produced. The coupling device 19 generates the detection signal S in response to an external switching signal 20 , for example, by a control unit and / or a microcontroller of the motor vehicle 1 can be generated. For example, the switching signal 20 in response to an actuation of an ignition or an ignition lock of the motor vehicle 1 be generated.

Through the coupling device 19 are in the in 1 illustrated example, the first terminal pole 10 and the second terminal pole 11 with the ground potential 6 connected. In this case, the coupling device 19 a first line branch 21 , a second line branch 22 and a third common leg 23 on. The common line branch 23 is over the first leg of the line 21 with the first connection 10 and over the second leg 22 with the second connection 11 connected. The common line branch 23 has a switchable connection element 24 which may be, for example, a semiconductor switching device with, for example, a transistor. A gate or base contact of the transistor may be connected to a switching input 25 for receiving the switching signal 20 be coupled.

If the electrical connection element 24 through the switching signal 20 is switched to an electrically conductive state, flows from the terminal poles 10 . 11 over the common circuit branch 23 a mass flow Ig to the ground potential 6 , For each line branch 21 . 22 may be a detection device 26 one detection element each 27 , For example, a measuring resistor or shunt resistor, above which a measuring voltage 28 decreases as a function of the mass flow Ig. The measuring voltage 28 can as the detection signal S to the control device 17 be transferred or forwarded. To even with electrically conductive connecting element 24 a potential of the supply line 4 and / or the terminal poles 10 . 11 from the ground potential 6 independently, each terminal pole can 10 . 11 via a power source circuit or short power source 29 the coupling device 19 with the connecting element 24 be coupled. Circuits for providing a power source 29 are known per se from the prior art.

2 illustrates how by means of a pulse length coding or pulse duration coding of the detection signal S by the control device 17 It can be detected whether the switching device 12 in the electrically conductive state 15 or the electrically blocking state 16 should be switched. Over the time t, a course of the mass flow Ig is illustrated, through which the voltage drop corresponding or correlating 28 and thus the detection signal S is generated. It is only required in Umschaltmoment a mass flow Ig, so that both switched off switching device 12 as well as switched on switching device 12 no control current or mass flow Ig must be performed. The current switching state 14 the control device 12 can at a signal output of the switching device 12 be signaled.

The pulse length coding may provide a predetermined reference duration Tr. Is a control pulse 30 shorter than Tr, then the switching device 12 in the electrically blocking state 16 connected. The switching time for the control pulse 30 is Toff <Tr. Is a control pulse 31 longer than Tr, then the switching device 12 in the electrically conductive state 15 connected. The control pulse 31 thus has a pulse duration tone, for which applies: sound> Tr. This results in a switching delay or a pickup delay of Tr and a dropout delay of Toff.

The currentless operation is made possible by the fact that the switching device 12 without operating voltage at the control input 18 is self-holding. But it can still further redundant control pulses 32 are sent, which are normally ineffective, but restore the desired switching state in the case of a false switch.

In a further embodiment, it is also possible to switch immediately when the rising edge and / or the falling edge occur, as a result of which the pull-in delay and / or drop-off delay is reduced.

In another embodiment, the current level or current of a current mirror of the power sources 29 can be varied, so that, for example, a triggering of a fuse function by an increased current intensity of the mass flow Ig of the control device 17 is reported back to an external controller (not shown).

Through a diode 33 becomes the device 7 AC compatible.

The example thus shows how the invention can provide a potential-free semiconductor relay with a non-operating drive.

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 2843496 A1 [0002]
• DE 112010006027 T5 [0003]
• DE 102008064393 A1 [0004]
• DE 102009029226 A1 [0005]
• DE 102009000593 A1 [0006]
• DE 202013104052 U1 [0007]

Claims (10)

Contraption ( 7 ) for controlling a current (I) in an electrical supply line ( 4 ) of a motor vehicle ( 1 ) in response to a switching signal ( 20 ), comprising: - a two-pole switching device ( 12 ) with a first connection pole ( 10 ) for connection to a source-side line part ( 8th ) of the supply line ( 4 ) and a second terminal pole ( 11 ) for connection to a consumer-side line part ( 9 ) of the supply line ( 4 ) and with a control input ( 18 ), - one with the control input ( 18 ) coupled control device ( 17 ) for setting a switching state ( 14 ) of the switching device ( 12 ) in dependence on a detection signal (S), characterized by - an electrical coupling device which is different from the supply line (S) ( 19 ) for coupling at least one of the terminal poles ( 10 . 11 ) with a ground potential ( 6 ) of the motor vehicle ( 1 ), wherein the coupling device ( 19 ) a controllable connecting element ( 24 ), which is adapted to the switching signal ( 20 ) and the at least one terminal pole ( 10 . 11 ) with the ground potential ( 6 ) electrically only if the switching signal ( 20 ), the coupling device ( 19 ) a detection device ( 26 ), which in dependence on a by the coupling device ( 19 ) to the ground potential ( 6 ) flowing mass flow (Ig) generates the detection signal (S). Contraption ( 7 ) according to claim 1, wherein the coupling device ( 19 ) each of the connection poles ( 10 . 11 ) with the ground potential ( 6 ) is interconnected. Contraption ( 7 ) according to one of the preceding claims, wherein the coupling device ( 19 ) a diode ( 33 ) whose flow direction from the at least one terminal pole ( 10 . 11 ) to the ground potential ( 6 ). Contraption ( 7 ) according to one of the preceding claims, wherein the detection device ( 26 ) for anyone with the ground potential ( 6 ) coupled terminal pole ( 10 . 11 ) each a power source ( 29 ) configured to set a current intensity of the ground current (Ig) to a predetermined value. Contraption ( 7 ) according to one of the preceding claims, wherein the control device ( 17 ) is adapted to the switching state ( 14 ) of the switching device ( 12 ) according to a predetermined pulse length coding as a function of a pulse duration (Toff, Ton) of the detection signal (S). Contraption ( 7 ) according to claim 5, wherein a reference duration (Tr) is predetermined by the pulse length coding and the control device ( 17 ) is adapted to a first switching state ( 16 ) of the switching device ( 12 ) at a pulse duration (Toff) smaller than the reference duration (Tr) and one to the first switching state ( 16 ) complementary second switching state ( 15 ) of the switching device ( 12 ) at a pulse duration (tone) greater than the reference duration (Tr). Contraption ( 7 ) according to one of the preceding claims, wherein the switching device ( 12 ) designed self-holding. Contraption ( 7 ) according to one of the preceding claims, wherein the switching device ( 12 ) for switching the current (I) at least one semiconductor switch ( 13 ) having. Motor vehicle ( 1 ) with a supply line ( 4 ) for electrically connecting an electrical voltage source ( 2 ) with at least one electrical consumer ( 5 ), wherein a source-side line part ( 8th ) and a consumer-side line part ( 9 ) of the supply line ( 4 ) via a device ( 7 ) are connected according to one of the preceding claims. Method for switching a current (I) in an electrical supply line ( 4 ) of a motor vehicle ( 1 ) in response to a switching signal ( 20 ), where - a two-pole switching device ( 12 ) with a first connection pole ( 10 ) for connection to a source-side line part ( 8th ) of the supply line ( 4 ) and a second terminal pole ( 11 ) for connection to a consumer-side line part ( 9 ) of the supply line ( 4 ) and with a control input ( 18 ) and - one with the control input ( 18 ) coupled control device ( 17 ) a switching state ( 14 ) of the switching device ( 12 ) in response to a detection signal (S), characterized in that - one of the supply line ( 4 ) various electrical coupling device ( 19 ) at least one of the terminal poles ( 10 . 11 ) with a ground potential ( 6 ) of the motor vehicle ( 1 ), wherein the coupling device ( 6 ) a controllable connecting element ( 24 ), which receives the switching signal ( 20 ) receives and the at least one terminal pole ( 10 . 11 ) with the ground potential ( 6 ) electrically connects only if the switching signal ( 20 ), and - the coupling device ( 19 ) a detection device ( 26 ), which in dependence on a by the coupling device ( 19 ) to ground potential ( 6 ) flowing mass flow (Ig) generates the detection signal (S).

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