Electronic fuse for at least one electrical line in a motor vehicle and procedures

Abstract

The invention relates to an electronic fuse (10) for at least one electrical line (14) in a motor vehicle, comprising at least one switching element (22) for switching the electrical line (14) and a control unit (24) for generating a control signal (26) for controlling the switching element (22), wherein the control unit (24) is configured to generate the control signal (26) based on a line protection algorithm, the line protection algorithm being implemented as at least one analog circuit (28) for generating the control signal (26). The invention further relates to a method for operating the electronic fuse.

Description

[0001] The following invention relates to an electronic fuse for at least one electrical line in a motor vehicle, comprising at least one switching element for switching the electrical line and a control unit for generating a control signal for controlling the switching element, wherein the control unit is configured to generate the control signal based on a line protection algorithm. Furthermore, the invention relates to a method for operating an electronic fuse according to the preceding aspect.

[0002] Electronic fuses, also known as cartridge fuses, are already known to replace traditional cartridge fuses in vehicle electrical systems. This is necessary due to functional safety requirements, which mandate very rapid, selective isolation of fault currents, such as short circuits, particularly within a few microseconds. Cartridge fuses, on the other hand, have a comparatively slow tripping time, often several milliseconds. Electronic fuses also offer advantages in terms of more precise adaptation to the circuit being protected. This can be utilized more effectively. Furthermore, unlike cartridge fuses, the switching state of electronic fuses is reversible.

[0003] The integrated protection mechanisms essentially consist of equipment protection, particularly thermal protection of the switching element, overcurrent time protection, and undervoltage protection. To ensure the safe operation of the line, the electronic fuses utilize a so-called line protection algorithm. If the line temperature exceeds a certain threshold, the switch of the switching element opens within the shortest possible time, thus preventing thermal overload.

[0004] The disclosure discloses an electronic safety circuit comprising: an electronic switch with a load current path which, in operation, is coupled to a load via a wire and is configured to connect or disconnect a load current supply node and the load via the wire depending on a control signal;a monitoring circuit configured to receive a current sensing signal representing the current flowing through the wire, to determine a first protection signal based on the current sensing signal and at least one wire parameter comprising a reference temperature, wherein the first protection signal indicates whether the load power supply node should be disconnected from the load via the wire, wherein the first protection signal is generated when an estimated wire temperature reaches or exceeds the reference temperature, and to generate a second protection signal indicating whether the estimated wire temperature reaches or exceeds a further reference temperature that is lower than the reference temperature;a logic circuit configured to receive the first protection signal and generate the control signal such that it causes the electronic switch to disconnect the load power supply node from the load when the first protection signal indicates that the load power supply node should be disconnected from the load; wherein the logic circuit is further configured to receive at least one selection signal and to set the at least one wire parameter based on the at least one selection signal.

[0005] The object of the present invention is to provide an electronic fuse and a method for operating the electronic fuse, by means of which improved protection of a line within an on-board network of a motor vehicle can be achieved.

[0006] This problem is solved by an electronic safeguard and by a method according to the independent claims. Advantageous embodiments are specified in the dependent claims.

[0007] One aspect of the invention relates to an electronic fuse for at least one electrical line in a motor vehicle, comprising at least one switching element for switching the electrical line and a control device for generating a control signal for controlling the switching element, wherein the control device is configured to generate the control signal on the basis of a line protection algorithm.

[0008] It is intended that the line protection algorithm is implemented as at least one analog circuit for generating the control signal.

[0009] The line protection algorithm in the control unit allows the procedure to be carried out with relatively little computational effort compared to other similar protection algorithms, such as RMS current calculation. The algorithm is particularly characterized by its exceptionally low memory requirements.

[0010] In particular, a multi-stage algorithm can be executed on a control unit with fewer computing resources, especially RAM and CPU, when used for multiple electronic fuses. This allows the CPU to be offloaded using an analog circuit. Line protection is thus possible without an active microcontroller in a power distribution unit, resulting in a reduction of operating and quiescent current. Furthermore, the adjustability of line protection characteristics is ensured, for example, with appropriate control elements within the analog circuit.

[0011] According to an advantageous embodiment, the analog circuit includes a temperature detection module for determining the temperature of the conductor and is configured to generate the control signal based on the determined temperature. In particular, this allows for a prediction of the conductor's future behavior based on its temperature. Based on this, it can then be reliably determined whether the temperature will rise to a level that could cause damage in the near future or is currently rising. Thus, a control signal can be generated based on the determined temperature, and, for example, if the temperature exceeds a threshold value, such as 80 degrees Celsius, the switching device can be opened, thereby interrupting the supply of electrical energy to a load within the conductor.

[0012] Another advantageous embodiment provides that the analog circuit includes a capacitance determination module for determining the thermal capacitance of the line and is configured to generate the control signal based on the determined thermal capacitance. The thermal capacitance can be determined, in particular, based on a target continuous current, where the continuous current is defined by the current the line carries up to its maximum temperature T. max It can be carried without time restrictions. Furthermore, a target impulse strength can be used, whereby the impulse strength in turn describes what the cable can withstand up to a maximum cable temperature T. max can be worn with a time limitation.

[0013] The thermal capacity of the line depends in particular on the insulation and conductor material.

[0014] Another advantageous embodiment provides that the analog circuit includes a resistance determination module for determining the thermal resistance of the conductor and is configured to generate the control signal based on this determined thermal resistance. The thermal resistance of the conductor can be determined, for example, based on heat convection or conduction. The thermal resistance, in turn, is also essentially dependent on the target continuous current. Thus, the electronic fuse can be operated reliably.

[0015] It is also advantageous if the line protection algorithm is provided in at least two stages, with a first stage configured as a first analog circuit and a second stage as a second analog circuit. In particular, the line protection algorithm can also be configured in at least three stages, and especially in four stages. Based on the different stages, particularly those that define the line protection differently, a multi-stage line protection system can thus be provided, enabling more reliable operation of the electronic fuse and therefore improved protection within the vehicle.

[0016] In particular, a further advantageous embodiment provides that the line protection algorithm is provided in at least three stages, with a first stage being a first analog circuit, a second stage a second analog circuit, and a third stage a third analog circuit, wherein, based on the first stage, a characteristic curve for the control signal is generated as a function of the product of a current in the line and time (It), and, based on the second stage, a characteristic curve for the control signal is generated as a function of a product of the square of the current (I). 2 ) is generated in the line and in time (I 2 t), and wherein, based on the third stage, a characteristic curve for the control signal is determined as a function of a maximum permissible current (I). peak) is generated in the line. This allows for a multi-stage characteristic curve, which enables reliable switching on and off of the line. In particular, this allows for improved circuitry of the electronic fuse.

[0017] It is further advantageous if the analog circuit includes at least a resistor structure and / or a linear regulator for setting at least one voltage value for the analog circuit. This allows for the specification of appropriate voltage values ​​for the analog circuit or for different analog circuits. This enables adaptation of the electronic fuse's operation.

[0018] It is also advantageous if the analog circuit is formed from at least one summing module and / or one multiplier module and / or one integrator module and / or one comparator module. Preferably, the analog circuit comprises at least one first summing module, one first multiplier module, one second multiplier module, one second summing module, one third multiplier module, one first integrator module, and at least one comparator module. Furthermore, the analog circuit may also include a Max module. This makes it possible to provide or generate the electronic fuse and, in particular, the control signal in a simple and essentially analogous manner.

[0019] In another advantageous embodiment, the switching device is designed as a disconnect switch or as a MOSFET. The MOSFET design, in particular, has proven to be significantly advantageous, as it allows for fast switching and the switching state can be reversed.

[0020] Another aspect of the invention relates to a method for operating an electronic fuse according to the preceding aspect, wherein a control signal for controlling the switching device of the electronic fuse is generated by means of a line protection algorithm implemented as an analog circuit.

[0021] Advantageous designs of electronic security are to be regarded as advantageous designs of the process. The electronic security essentially possesses tangible features to enable the execution of the corresponding procedural steps.

[0022] Further features of the invention will become apparent from the claims, the figures, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown in the figures alone, are not only usable in the combinations specified, but also in other combinations or on their own.

[0023] The invention will now be explained in more detail with reference to a preferred embodiment and the drawings. The drawings show: Fig. 1 a schematic block diagram according to an embodiment of an electronic fuse in an electrical on-board network of a motor vehicle not shown; Fig. 2 a schematic block diagram according to an embodiment of a summation module; Fig. 3 a schematic block diagram according to an embodiment of a multiplier module; Fig. 4 a schematic block diagram according to an embodiment of a Max module; Fig. 5 a schematic block diagram according to an embodiment of a comparator module; and Fig. 6 a schematic block diagram according to an embodiment of an integrator module.

[0024] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0025] Fig. Figure 1 shows a schematic block diagram according to an embodiment of an electronic fuse 10 for a motor vehicle (not shown). The electronic fuse 10 is designed, in particular, to interrupt the current flow from an electrical energy storage device 12 of the motor vehicle to a line 14 of the motor vehicle. The line 14, in turn, can be connected, for example, to an electrical consumer 16. In the present embodiment, the electrical line 14 is represented, in particular, by an ohmic resistor 18 and an inductor 20.

[0026] The electronic fuse 10 has, in particular, at least one switching element 22, for example in the form of a mechanical disconnect switch, but especially in the form of a MOSFET.

[0027] In particular, this shows that Fig. 1 the electronic fuse 10 for the at least one line 14 in the motor vehicle, with at least the switching element 22 for switching the electrical line 14 and with a control device 24 for generating a control signal 26 for controlling the switching element 22, wherein the control device 24 is designed to generate the control signal 26 on the basis of a line protection algorithm.

[0028] It is provided that the line protection algorithm is designed as at least one analog circuit 28 for generating the control signal 26.

[0029] In particular, it is provided that the analog circuit 28 has at least one temperature determination module 30 for determining the temperature of the line 14 and is configured to generate the control signal 26 based on the determined temperature. Furthermore, the Fig. 1 In particular, it is shown that the analog circuit 28 has a capacitance determination module 32 for determining the thermal capacitance of the line 14 and is configured to generate the control signal 26 based on the determined thermal capacitance. Furthermore, it is shown that the analog circuit 28 can have a resistance determination module 34, wherein the resistance determination module 34 is configured to determine a thermal resistance of the line 14 and is additionally configured to generate the control signal 26 based on the determined thermal resistance.

[0030] In particular, it may be provided that the electronic fuse 10 may additionally have a current determination module 36 which can measure or determine a current I within the line 14.

[0031] The Fig. Figure 1 further shows that the line protection algorithm is provided in at least two stages, with a first stage 38 configured as a first analog circuit and a second stage 40 configured as a second analog circuit. It can also be provided that the line protection algorithm is provided in at least three stages, with the first stage 38 configured as a first analog circuit, the second stage 40 as a second analog circuit, and a third stage 42 as a third analog circuit. Based on the first stage 38, a characteristic curve for the control signal 26 is generated as a function of a product of a current I and time t (It). Based on the second stage 40, a characteristic curve for the control signal 26 is generated as a function of a product of the square of the current (I). 2 ) in line 14 and time t (I 2t) is generated, and wherein, based on the third stage 42, a characteristic curve for the control signal is obtained as a function of a maximum permissible current (I) peak ) is generated in the line.

[0032] Furthermore, it may be provided in particular that the analog circuit 28 has at least a resistor structure and / or a linear regulator for setting at least one voltage value for the analog circuit 28.

[0033] Furthermore, it is specifically provided that the analog circuit 28 can be formed from at least one summation module 44 and / or a multiplier module 46 and / or a comparator module 48 and / or an integrator module 50. A Max module 52 is also specifically shown.

[0034] In particular, this shows that Fig. 1, that a voltage U is generated by means of the electrical energy storage device batThe power supply for the electrical load 16 can be provided via line 14. Line 14 is modeled in particular as resistance 18 and inductance 20 and can be protected against thermal overload by means of the electronic fuse 10. The integrated protection mechanisms of the electronic fuse 10 are provided in particular for equipment protection, for example thermal protection of the MOSFET, overcurrent time protection, in particular thermal line protection, and overcurrent protection, which is represented in particular by the line protection algorithm, as well as undervoltage protection.

[0035] The electronic fuse 10 uses the line protection algorithm to ensure the safe operation of line 14. If a certain temperature of line 14 is exceeded, the switch or switching element 22 is opened within the shortest possible time to prevent thermal overload.

[0036] In particular, the temperature of line 14 is determined using: TC=I2Rref(1+α[Tc−Tref])−TC−TaRthsCth where T a The ambient temperature of line 14 in the design corresponds, for example, to 80 °C, s of the Laplace variable, R ref an ohmic resistance 18 of the line 14 at a reference temperature T ref of 25 °C, α is a linear temperature coefficient of the conductor material, for example 0.00391:K for copper, I is the electric current, C th the thermal capacity of line 14 and R thThe thermal resistance of the conductor is the answer. In particular, a fictitious thermal impedance of the conductor can be calculated using the formula: C'th=QI2t,tar(1+α[Tc−Tref])Tc−Ta and a fictitious thermal resistance of line 14 with the formula: R'th=Tc−TaItarx(1+α[Tc−Tref]) be determined. tar This represents the target continuous current. The continuous current is the current that line 14 carries up to the maximum line temperature T. max can be worn without time restrictions. Q I2t,tar This corresponds to the target impulse withstand capability. The impulse withstand capability is specified as the maximum line temperature T. max with a time limit that line 14 can bear.

[0037] The fictitious thermal conductivity model is given by the formula: Tc=Ix(1+α[Tc−Tref])−TC−TaRthsCth

[0038] In particular, this shows that Fig. 1. Analog circuit 28 for multi-stage protection. The advantages of the line protection algorithm lie particularly in its relatively low computational effort compared to other similar protection algorithms. The line protection algorithm is characterized by a particularly low memory requirement. Due to the multi-stage implementation, not only the isotherm of line 14 can be protected, but also, for example, other equipment, such as the MOSFET or the underlying current-time characteristic of another protective device. This is particularly feasible using this type of multi-stage characteristic curve. The multi-stage line protection algorithm, when used with the electronic fuse 10 on a control unit, requires few computing resources, especially RAM and CPU. This relieves the CPU of the burden of processing by analog circuit 28.The analog circuit 28 enables line protection without an active microcontroller, thereby reducing both operating and quiescent current. Furthermore, the line protection characteristic is adjustable, particularly for example, using linear regulators or resistor structures.

[0039] Fig. Figure 2 shows an embodiment of a summing module 44. In particular, three input signals 54 are shown. Furthermore, input filters 56 are shown, which can be formed via capacitors 58 and ohmic resistors 60. An operational amplifier 62 and an adjustable resistor 64 are also shown.

[0040] Fig. Figure 3 shows an embodiment of a multiplier 46. In particular, several operational amplifiers 62 are shown. Furthermore, several ohmic resistors 60 are shown. The figure also shows... Fig. 3 especially the electrical mass 66.

[0041] Fig. Figure 4 shows an embodiment of a Max module 52. In particular, several input signals 54, operational amplifiers 62, diodes 68, and ohmic resistors 60 are shown. Furthermore, a transistor 70 and output signals 72 are shown.

[0042] Fig. Figure 5 shows an embodiment of a comparator module 48. Here, an operational amplifier 62, a reference voltage 74, an ohmic resistor 60 and an input signal 54, in particular in the form of an input voltage, are shown.

[0043] Fig. Figure 6 shows a schematic example of an embodiment of an integrator module 50. The integrator module 50 again comprises ohmic resistors 60, a capacitor 56, and an operational amplifier 62. Furthermore, an input signal 54 is shown in particular. Reference symbol list 10 electronic fuses 12 electrical energy storage devices 14 Management 16 consumers 18 Ohm resistance 20 Inductance 22 Switching element 24 Control unit 26 Control signal 28 Analog circuit 30 Temperature determination module 32 Capacity Determination Module 34 Resistance determination module 36 Current measuring device 38 first stage 40 second stage 42 third stage 44 Summation module 46 Multiplier module 48 Comparator module 50 Integrator module 52 Max module 54 Input signal 56 Filter system 58 capacity 60 Ohm resistance 62 operational amplifiers 64 adjustable resistance 66 mass 68 Diode 70 transistors 72 Output signal 74 Reference voltage

Claims

[1] Electronic fuse (10) for at least one electrical line (14) in a motor vehicle, comprising at least one switching element (22) for switching the electrical line (14) and a control unit (24) for generating a control signal (26) for controlling the switching element (22), wherein the control unit (24) is configured to generate the control signal (26) on the basis of a line protection algorithm, characterized by , that the line protection algorithm is implemented as at least one analog circuit (28) for generating the control signal (26). [2] Electronic fuse (10) according to claim 1, characterized by , that the analog circuit (28) has a temperature determination module (30) for determining a temperature of the line (14) and is designed to generate the control signal (26) on the basis of the determined temperature. [3] Electronic fuse (10) according to claim 1 or 2, characterized by, that the analog circuit (28) has a capacitance determination module (32) for determining a thermal capacitance of the line (14) and is designed to generate the control signal (26) on the basis of the determined thermal capacitance. [4] Electronic fuse (10) according to any one of the preceding claims, characterized by , that the analog circuit (28) has a resistance determination module (34) for determining a thermal resistance of the line (14) and is designed to generate the control signal (26) on the basis of the determined thermal resistance. [5] Electronic fuse (10) according to any of the preceding claims, characterized by , that the line protection algorithm is provided in at least two stages and a first stage (38) is designed as a first analog circuit and a second stage (40) as a second analog circuit. [6] Electronic fuse (10) according to any of the preceding claims, characterized by, that the line protection algorithm is provided in at least three stages and a first stage (38) is designed as a first analog circuit and a second stage (40) as a second analog circuit and a third stage (42) as a third analog circuit, wherein on the basis of the first stage (38) a characteristic curve for the control signal (26) is generated as a function of a product of a current in the line (14) and time, wherein on the basis of the second stage (40) a characteristic curve for the control signal (26) is generated as a function of a product of the square current in the line (14) and time, and wherein on the basis of the third stage (42) a characteristic curve for the control signal (26) is generated as a function of a maximum permissible current in the line (14). [7] Electronic fuse (10) according to any of the preceding claims, characterized by, that the analog circuit (28) has at least a resistor structure and / or a linear regulator for setting at least one voltage value for the analog circuit (28). [8] Electronic security (10) according to any of the preceding claims, characterized by , that the analog circuit (28) is formed from at least one summation module (44) and / or a multiplier module (46) and / or an integrator module (50) and / or a comparator module (48). [9] Electronic security (10) according to any of the preceding claims, characterized by , that the switching element (22) is designed as a disconnect switch or as a MOSFET. [10] Method for operating an electronic fuse (10) according to one of claims 1 to 9, wherein a control signal (26) for controlling a switching element (22) of the electronic fuse (10) is generated by means of a line protection algorithm implemented as an analog circuit (28).

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