Abstract:
A device and method for fuse protection of a line includes at least two sensors for sensing a corresponding electric variable in a first location and a second location along a conductor line, and for outputting a corresponding first value and second value of the electric variable at the first and second locations, respectively. An evaluation unit evaluates the generated first and second values in order to generate an evaluation result. The evaluation unit controls, based on the evaluation result, an isolating element to cause the isolating element to interrupt a current flow in the conductor line.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of prior German Application No. 10 2014 111 416.7, filed on Aug. 11, 2014, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present disclosure relates to a device for fuse protection of a line. The present disclosure further relates to a method for fuse protection of a line. 
     BACKGROUND OF THE DISCLOSURE 
     Parallel arcs can develop in an on-board electric system in a vehicle having an operating voltage of 24V or 48V, for example; on the one hand, these arcs limit the current so that a fusible cutout is not triggered, but on the other hand, they can cause a fire in the vehicle. 
     Furthermore, a serial arc that cannot be protected by a fusible cutout due to resulting current, which is lower than the load current, may develop if a cable break occurs in the on-board electric system. Such a serial arc can also cause a fire. 
     It is known that additional lines (e.g., measurement lines, e.g., in the form of a shielding) may be provided and coupled to an electronic evaluation system that detects a change in resistance or potential. One disadvantage here is that additional lines are expensive. Furthermore, a measurement line connected to a useful line may be difficult and complicated to contact; this can result in expensive plugs, for example. Disturbances on the measurement line may have effects that additionally reduce the reliability of the evaluation and/or make the electronic evaluation system more expensive due to additional measures such as filters, for example. This can also result in taking too long of a time to detect short circuits. 
     SUMMARY 
     Embodiments of the present disclosure may avoid the disadvantages mentioned above and provide a solution for a rapid and reliable shutdown in the event of a fault. In the event of a parallel and/or serial arc for example, a single line or a collective line can be reliably isolated from the power supply voltage. This may be achieved by a device and method for fuse protection of a line. According to this disclosure, there is provided a device for fuse protection of a line having at least one sensor on the basis of which an electric variable can be determined in at least two locations on a line, and having an evaluation unit, on the basis of which the electric variables can be evaluated, wherein the evaluation unit may be set up to control the isolating element as a function of the result of an evaluation, so that it interrupts a current flow in the line. Thus, the evaluation unit may control, based on the evaluation result, an isolating element to interrupt a current flow in a conductor line. 
     The electric variables may include, for example, a current, a voltage, or a magnetic field (for example, magnetic flux density). The sensor may output one electric variable or a plurality of electric variables. Values of electric variables may be output. One electric variable may be supplied by the sensor per location on the line. It is also possible that one individual sensor determines the electric variable(s) in two locations on the line; for example, a magnetic field may be determined by means of a single sensor in two locations on the line which are near one another. As another example, at least two sensors may sense a corresponding electric variable in a first location and a second location along a conductor line, and may output a corresponding first value and second value of the electric variable at the first and second locations, respectively. 
     The isolating element may be a contactor or a relay, or a fuse, for example. The isolating element can also be controlled by the evaluation unit, which may be an evaluation circuit. In this way, the electric circuit can be interrupted by the isolating element via the evaluation circuit. For example, the device can be set up so that the isolating element is opened in the currentless state of the evaluation unit. 
     It is a further aspect of the disclosure that the line may be a power supply line between a battery and at least one load. 
     It is another aspect of the disclosure that the at least two locations may be near one another. 
     For example, the two locations may be locations on a line that represent connecting lines to and/or from a load, and they may be arranged nearby, so that a magnetic field or a change in magnetic field induced by the connecting lines can be detected by means of a sensor, for example. The means of a sensor may, for example, be a single sensor. 
     It is a further aspect of the disclosure that the sensor may include a resistor in the line, wherein a voltage on the resistor can be evaluated by the evaluation unit. 
     It is also a further aspect of the disclosure that the sensor may comprise a Hall sensor, wherein a Hall voltage can be evaluated by the evaluation unit. 
     Furthermore, it is another aspect of the disclosure that the sensor may comprise at least one giant magnetoresistance (GMR) sensor. 
     In an additional aspect of the disclosure, the sensor may comprise a bridge circuit having at least one GMR sensor, and may be a full bridge circuit having two GMR sensors. 
     A next aspect of the includes that the sensor may be mechanically connected to the line. 
     For example, the sensor may be arranged on a circuit board (for example, a flexible circuit board), which may be mechanically connected to the line. 
     In some embodiments, a comparison comprising at least one formation of a difference can be performed on the basis of the evaluation. 
     For example, there may be at least one comparison of at least two electric variables with one another and/or with at least one predefined threshold value, for example. 
     Some embodiments may include setting up the evaluation unit, so that two measured electric variables may be compared in a first comparison, and the result of the evaluation may be determined by comparing the result of the first comparison with a predefined threshold value in a second comparison. 
     For example, the isolating element may be opened if the result of the first comparison yields an indication of a current that is higher than the predefined threshold value. The isolating element may remain closed if the current is lower than the predefined threshold value. 
     For example, the evaluation unit can also compare the electric variable(s) with at least one predefined threshold value and can trigger the isolating element based on the evaluation result obtained in this way. 
     In some embodiments, the electric variable may be a voltage, a current, or a power, or may be based on a magnetic variable. 
     In some embodiments one sensor may be provided in each power supply line and in each ground line. 
     According to this disclosure, there is also provided a method for fuse protection of a line, in which an electric variable may be determined in at least two locations on a line by means of at least one sensor, the electric variables thereby determined may then be evaluated and an isolating element may be triggered as a function of the result of an evaluation, so that the isolating element interrupts a current flow in the line. 
     A further aspect of the disclosure may include comparing two measured electric variables with one another in a first comparison, and determining the result of the evaluation by comparing, in a second comparison, the result of the first comparison with a predefined threshold value. 
     In some embodiments, the isolating element may be opened if the result of the first comparison is greater and/or less than the predefined threshold value. 
     In some embodiments, the result of the evaluation may be determined based on two electric variables or on chronologically successive values of an electric variable. 
     It is therefore possible that an evaluation may be based on two electric variables, e.g., voltages or currents occurring almost simultaneously. Alternatively (or additionally), the evaluation may be based on a change in at least one electric variable (e.g., voltage, current, magnetic field) over time. In both cases, a threshold value comparison may be performed, for example, and the isolating element can be opened on reaching and/or exceeding, or even falling below the threshold value. 
     A fuse device comprising at least one of the devices described here is also provided to achieve that described in this disclosure. 
     Said fuse device may also be interpreted as a fuse system. 
     In the context of an aspect of this disclosure, the fuse device can be used in an operating network, such as in an on-board electric system, for example a 48V on-board electric system, in a motor vehicle. 
     The approach presented in this disclosure also includes a computer program product, which can be loaded directly into a memory in a digital computer and may comprise program code parts suitable for performing steps of the methods described. 
     The evaluation unit may be embodied as a processor unit and/or an at least partially hardwired or logic circuit configuration, which may be set up so that, for example, the method can be performed as described herein. Said evaluation unit may be or may comprise any type of processor or computer having the required peripherals (memory, input/output interfaces, input/output devices, etc.) accordingly. 
     The explanations given pertaining to methods may also apply to the devices accordingly and vice versa. The devices may be embodied in one component or distributed among multiple components. 
     The properties, features and advantages as described above as well as the type and manner of how they are achieved can be understood more clearly and more distinctly in conjunction with the following schematic description of embodiments, which are explained in greater detail in conjunction with the drawings. For the sake of simplicity, the same elements or those having the same effect may be provided with the same reference numerals. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       Further details and advantages of the embodiments will be described hereafter with reference to the figures. 
         FIG. 1  shows a schematic circuit diagram for a differential current measurement at two locations on a line. 
         FIG. 2  shows a schematic circuit diagram for a differential current measurement using a Hall sensor. 
         FIG. 3  shows an alternative circuit diagram for a differential current measurement using two Hall sensors. 
         FIG. 4  shows a circuit diagram for a differential current measurement using two Hall sensors based on the diagram of  FIG. 3 , wherein, instead of the load, multiple loads are connected in parallel. 
         FIG. 5  shows a power supply line to be secured having two contacts, wherein a sensor device is arranged on or near each of the contacts as an example. 
         FIG. 6  shows a sensor device, which is connected to a cable with a terminal end. 
         FIG. 7  shows a current distributor having a plurality of cables, each cable being detachably connected to the current distributor by means of a screw assembly, and each cable having a sensor device directly on the cable. 
         FIG. 8  shows a circuit diagram comprising two sensor devices, which are embodied as GMR full bridges and are arranged on both ends of a power supply line to be monitored. 
         FIG. 9  shows a circuit diagram based on  FIG. 8  having two power supplies for the two sensor devices. 
     
    
    
     DETAILED DESCRIPTION 
     Currents occurring on a feeder line from a power supply to a load, for example, often cannot be differentiated clearly with regard to a fault current or a current during normal operation. Some disturbances may therefore remain undetected and cannot lead to triggering of a fuse, for example a fusible cutout. One example of such a disturbance is a parallel arc, for example, a parallel short circuit, which leads to a limited but unwanted current flow. 
     It is proposed that an electric variable, for example, a current and/or a voltage, may be determined in at least two locations or points on a line and evaluated. The at least two locations may be a distance apart from one another or near to one another. Different sensors may be used to determine the electric variable. It is possible that at least one measuring bridge may be used to determine the electric variable. An evaluation unit may comprise, for example, a comparison of the electric variables determined. For example, an isolating element, such as a contactor or a relay, may be controlled by the evaluation unit so that it is interrupted when a fault current of the electric circuit is detected, for example, between a power source and a load. 
     A giant magnetoresistance (GMR) sensor, magnetic field sensor, or Hall sensor which may be based on the Hall effect for measuring magnetic fields, may be used to determine the electric variable, for example. The GMR sensor, which may also referred to as a GMR element, may be used in a bridge circuit with ohmic resistors, for example. 
     A so-called giant magnetoresistance (GMR) effect may be observed in structures consisting of alternating magnetic and nonmagnetic thin layers with a layer thickness of a few nanometers. This effect may cause the electric resistance of the structure to depend on the mutual orientation of the magnetization of the magnetic layers and may be much higher with magnetization in opposite directions than with magnetization in the same direction. 
     A temperature compensation may optionally take place. 
     The approach proposed here can be used in existing systems, including their lines and/or their plug systems. 
     Such a parallel short circuit can be detected by the comparison of the electric variable determined in various locations, for example, in the form of a calculated difference. This approach may not require any additional lines (e.g., with multiple shielding or measurement lines), which may facilitate use in existing systems. 
       FIG. 1  shows a schematic circuit diagram for a differential current measurement in two locations on a line  101 . 
     The line  101  connects a battery  102  to a load  103  via an isolating element  104 . A measuring shunt  105  may be arranged at a first location in the line  101 , and a measuring shunt  106  may be arranged at a second location. The measuring shunts  105  and  106  may also be referred to as shunt resistors. A voltage drop at the measuring shunt  105  (which may be proportional to a current  11  through the measuring shunt  105 ) may be sent to an evaluation unit  109  via an amplifier  107 . A voltage drop across the measuring shunt  106  (which may be proportional to a current  12  through the measuring shunt  106 ) may be sent to the evaluation unit  109  via an amplifier  108 . The voltage drops across the measuring shunts  105  and  106  (and therefore also those currents through the measuring shunts  105  and  106 ) may be compared with one another by the evaluation unit  109 , and the isolating element  104  may be opened by the evaluation unit  109  as a function of the result of the comparison, so that the battery  102  is isolated from the load  103 . 
     Therefore, parallel arcs can be detected in this way. For example, an arc current in the case of a parallel arc may be greater than 5 A. If the current difference between the currents  11  and  12  is greater than 5 A, then there may be a parallel arc or a short circuit. The isolating element  104  may then be opened by the evaluation unit  109 , therefore interrupting the current flow from the battery  102  to the load  103 . 
     It should be pointed out here that the battery may be any electric power source, such as an on-board electric system for a motor vehicle, for example. The load may be a consumer, for example a control unit or an actuator in the vehicle. 
       FIG. 2  shows a schematic circuit diagram of the differential current measurement using a Hall sensor  203 . 
     Again, a line may connect the battery  102  to the load  103  via the isolating element  104 . The line may comprise a line section  201 , which may be a power supply line, to the load  103 , and a line section  202 , which may be a ground line, from the load. A magnetic field of the line sections  201  and  202  may be detected by the Hall sensor  203  and the resulting Hall voltage may be sent via an amplifier  204  to an evaluation unit  205 . 
     If a Hall sensor  203  has a current flowing through it and is brought into a magnetic field running perpendicular to the current, it may supply an output voltage proportional to the product of the magnetic field strength and the current, which may be a Hall effect. In this example, a separate power supply may be provided for the Hall sensor  203 , which may be brought into the magnetic field of the conductor, here, the line sections  201  and  202 . 
     For example, the magnetic fields of the two line sections  201  and  202 , through which the same current is flowing in opposite directions, may be isolated almost completely, so that the Hall sensor outputs almost no signal. 
     In the case of a parallel arc a portion of the current may flow to ground via the arc. The difference in the current through the line section  201  and the current through the line section  202  may lead to a magnetic field that can be detected by the Hall sensor  203  and therefore to a signal voltage (Hall voltage) output by the Hall sensor  203 . This change in the Hall signal voltage may be utilized as a fault signal by the evaluation unit  205  to open the isolating element  104  and to interrupt the current flow from the battery  102  to the load  103 . 
       FIG. 3  shows an alternative circuit diagram for the differential current measurement using two Hall sensors  301  and  302 . 
     The Hall sensor  301  may be placed in a line section  305 , which may be a power supply line, between the battery  102  and the load  103 , and the Hall sensor  302  may be placed in a line section  306 , which may be a ground line, between the load  103  and ground. 
     The Hall sensor  301  may supply a Hall voltage to the first input of an amplifier  303 , which may be a comparator, and the Hall sensor  302  may supply a high voltage to the second input of the amplifier  303 . The output of the amplifier  303  may be connected to an evaluation unit  304 . 
     The evaluation unit  304  can determine, for example on the basis of at least one threshold value comparison, whether the current detected by the Hall sensor  301  deviates from the current detected by the Hall sensor  302  by more than a predefined value and can, if necessary, open the isolating element  104  to interrupt the current flow between the battery  102  and the load  103 . 
     According to the diagram shown in  FIG. 3 , it is therefore possible to also monitor the feeder lines to the load  103  by appropriate positioning of the Hall sensors. 
     It is possible that a plurality of sensors, such as Hall sensors, for example, may be provided at different locations in a system, such as a motor vehicle for example. A measured signal may be output to the evaluation unit, for example, via an amplifier, and the evaluation unit may perform a comparison with other measured signals or threshold values to determine whether there is a fault. In the event of a fault, the isolating element  104  may be opened as shown in the figure, for example. 
       FIG. 4  shows a circuit diagram for the differential current measurement using two Hall sensors  301  and  302 , based on the diagram in  FIG. 3 , wherein, instead of the load  103 , a plurality of loads  401  to  404  are connected in parallel. 
     Accordingly, a sum signal to the loads  401  to  404  may be compared with a sum signal from the loads  401  to  404  to ascertain whether a fault case, such as a parallel arc for example, has occurred and the isolating element  104  may be opened accordingly. 
     Therefore, using the difference in the currents through the feeder lines  305  and  306 , it is possible to reliably ascertain a short circuit within the group of loads  401  to  404  and therefore also to monitor the feeder line. 
     This approach may be advantageous when the loads  401  to  404  are difficult or impossible to differentiate. This approach may also be advantageous if the loads  401  to  404  can be provided with sensors individually only at great expense. 
     An imbalance between a current input into a line and a current output from the line can be determined by means of a measuring bridge. The respective current may be detected on the basis of the magnetic field surrounding the conductor. A GMR sensor or a Hall sensor, for example, may be suitable for such a current determination. 
       FIG. 5  shows a power supply line  501 , which may be a feeder line, to be secured, having two contacts  502  and  503 , with one sensor device  504 , and another sensor device  505  being arranged on or in the vicinity of each of the contacts  502  and  503 , for example. The sensor devices  504  and  505  may be interconnected via a dual-core line  506  (which may be a “twisted-pair” line, for example). The sensor devices  504  and  505  may optionally have a connection relating to their electric power supply. 
     For example, the sensor device  504  may be permanently or detachably connected to the power supply line  501  and/or to the contact  502 . Another option may be for the sensor device  505  together with the contact  503  to be arranged in a current distributor  507 . Also, the current distributor  507  may have an evaluation unit. 
     Therefore, the magnetic field or B field, which may be based on the current flow through the power supply line  501 , may be measured by means of the respective sensor device  504  and  505 . Such a B field measurement, which may be a current measurement, may be performed on or in the vicinity of the contacts  502  and  503 , for example, at opposite points on the power supply line  501  to be monitored. Hall sensors with a magnetic circuit or GMR sensors may be used to measure the B field. A closed magnetic circuit may not be necessary in the case of GMR sensors. 
     In the case of a parallel arc, a portion of the current may flow to ground over the arc and may detune the bridge circuit with the GMR elements. Such detuning can be detected by means of the evaluation unit, and the isolating element may be opened and the power supply interrupted as a result. 
       FIG. 8  shows a circuit diagram comprising a sensor device  801 , which may be embodied as a GMR full bridge, and a sensor device  802 , which may also embodied as a GMR full bridge. Both sensor devices  801  and  802  may be connected to a power supply  803 . The center taps of the sensor device  801  may be connected to an evaluation unit  805  via a twisted dual-core line  804 . The center taps of the sensor device  802  may also connected to the evaluation unit  805 . 
     Each of the full bridges may have a parallel circuit of two strands, wherein each strand may have a series circuit of a GMR element and a resistor. In the example embodiment, the strands may be in an anti-parallel arrangement, where each node of the parallel circuit may be connected to a GMR element of the one strand and to a resistor of the other strand. 
     The sensor device  801  may have the GMR elements  806  and  807 , and the resistors R 1  and R 2  accordingly. The sensor device  802  may have the GMR elements  808  and  809 , and the resistors R 3  and R 4  accordingly. 
     The evaluation unit  805  may determine a differential voltage U 1  between the voltages on the center taps of the full bridge of the sensor device  801  and a differential voltage U 2  between the voltages on the center taps of the full bridge of the sensor device  802 . The evaluation unit may supply a differential voltage Udelta according to
 
 U delta=| U 2− U 1|.
 
     The sensor devices  801  and  802  can be placed at different locations on a line, as described above. According to the example shown in  FIG. 8 , four cores in total, parallel to the line, may be required (two cores for the power supply of the sensor device  801  and two cores for supplying the voltages at the center taps of the full bridge). 
     This embodiment may be advantageous when both sensor devices  801  and  802  can be supplied with power from the system voltage  803  and therefore the voltage drop over the line may be additionally detected. 
     A serial arc can also be detected on the basis of the voltages on the center taps of the full bridges of the sensor devices  801  and  802 . 
     The two sensor devices  801  and  802  may be arranged opposite one another and can advantageously be integrated on or in the vicinity of the line to be monitored, based on their electric variable. The effect of possible interference may be reduced due to the twisted dual-core line  804 . 
     The line may be combined with existing plug systems. The sensor device  802  may be arranged together with the evaluation unit  805  in a current distributor. 
     This example embodiment may permit a flexible and efficient means of securing a sum current line. 
       FIG. 9  shows a circuit diagram based on  FIG. 8 , wherein a power supply voltage  901  is additionally provided for the sensor device  801 . Therefore, one core may be omitted and the power supply voltages  901  and  803  depend on a common ground line. 
       FIG. 6  shows a sensor device  601 , which may be arranged on a circuit board or a flexible circuit board, for example, and may be connected to a cable with a terminal end  602 . The sensor device  601  may be surrounded by a shrink tubing  603 . 
       FIG. 7  shows a current distributor  701  with a plurality of cables  702 , wherein each of the cables  702  may be detachably connected to the current distributor  701  by means of a screw connection  704 , and each cable  702  may have a sensor device  703  directly on the cable. The cable  702  can be secured by means of line fixation devices  705 . 
     The sensor devices may also be arranged directly beneath the lines on a shared circuit board. For example, a receptacle for the lines may be provided, which may determine a defined positioning of the respective line on the sensor device. The evaluation unit for the sensor devices may be arranged on the circuit board. 
     According the above example embodiment, it may be advantageous that only a small installation space is required for the sensor device. Mechanical fastening parts for the sensor device may also be obsolete. 
     The explanations provided with reference to the figures are merely illustrative and shall not be understood to have any limiting effect. It is possible to make various modifications to the described embodiments without departing from the scope of protection as it is defined in the accompanying claims. 
     LIST OF REFERENCE NUMERALS 
       101  line 
       102  battery 
       103  load 
       104  isolating element 
       105  measuring shunt 
       106  measuring shunt 
       107  amplifier 
       108  amplifier 
       109  evaluation 
       201  power section 
       202  power section 
       203  Hall sensor 
       204  amplifier 
       205  evaluation unit 
       301  Hall sensor 
       302  Hall sensor 
       303  amplifier 
       304  evaluation unit 
       305  power section 
       306  power section 
       401  load 
       402  load 
       403  load 
       404  load 
       501  power supply line 
       502  contact of the power supply line  501   
       503  contact of the power supply line  501   
       504  sensor device 
       505  sensor device 
       506  dual-core line 
       507  current distributor 
       601  sensor device 
       602  terminal end 
       603  shrink tubing 
       701  current distributor 
       702  cable 
       703  sensor device 
       704  screw connection 
       705  line fixation 
       801  sensor device 
       802  sensor device 
       803  battery 
       804  dual-core line 
       805  evaluation unit 
       806  GMR element (GMR sensor) 
       807  GMR element (GMR sensor) 
       808  GMR element (GMR sensor) 
       809  GMR element (GMR sensor) 
     R 1  resistor 
     R 2  resistor 
     R 3  resistor 
     R 4  resistor 
       901  battery