ELECTRONIC DIAGNOSTIC CIRCUIT FOR FUNCTIONAL TESTING OF A PROTECTIVE CIRCUIT FOR AN ELECTRONIC FUSE ELEMENT

Abstract

The disclosure relates to an electronic diagnostic circuit (110) for functionally testing a protective circuit (120) for an electronic fuse element (M1) in a vehicle, wherein the protective circuit (120) comprises an RC element (R1, C1) connected in parallel with the electronic fuse element (M1). The electronic diagnostic circuit (110) comprises: a current source (111) designed to charge the RC element (R1, C1) when the electronic fuse element (M1) is in the off state; and an evaluation electronic circuit (112) designed to detect a voltage waveform (121) at the electronic fuse element (M1). The evaluation electronic circuit (112) is designed to indicate a fault condition of the protective circuit (120) and / or the electronic fuse element (M1) in the event of a deviation between the detected voltage waveform (121) and a predetermined voltage waveform (121e).

Description

Technical area

[0001] The present invention relates to an electronic diagnostic circuit for functionally testing a protective circuit for an electronic fuse element in a vehicle, particularly an electric vehicle. The invention particularly relates to diagnostic techniques for functionally testing an RCD or RCD snubber. State of the art

[0002] High-voltage (HV) semiconductor switches require reliable shutdown. Especially when used as a fuse (electronic fuse) and equipped with an ASIL-level function (for safe disconnection of a current), the reliability of shutdown must be guaranteed throughout the product's lifetime. To determine this throughout the product's lifetime, a diagnosis of the semiconductor used and its peripherals is necessary.

[0003] When a current is interrupted using a semiconductor, the energy stored in the circuit must be dissipated as a result of the flowing current. This can be achieved using a so-called snubber circuit. Similar to a semiconductor, this circuit must also operate reliably and be diagnosable. Currently, no diagnostic circuits for snubber circuits are known. Likewise, no semiconductor fuses with ASIL functions for safely interrupting HV currents are known.

[0004] In the low-voltage range, TVS diodes are primarily used as a means of dissipating energy. However, TVS diodes cannot be used in the HV range because they lack sufficient dielectric strength.

[0005] To date, fuses have been used in the automotive sector to protect against short circuits and overcurrents. A diagnostic circuit is neither known nor necessary, as the fuse would be destroyed or rendered unusable if the circuit is shut down. Description of the invention

[0006] One object of the invention is therefore to create a concept for diagnosing a protective circuit for a high-voltage semiconductor switch, in particular for a snubber circuit, that reliably detects whether the protective circuit is still functioning reliably. The diagnosis is to be carried out, in particular, while the vehicle is in operation.

[0007] The object is achieved by the subject matter of the independent claims. Advantageous developments of the invention are specified in the dependent claims, the description, and the accompanying figures.

[0008] The inventive solution is based on the idea of creating a suitable electronic diagnostic circuit for functional testing of the protective circuit, in particular the snubber circuit, for the high-voltage semiconductor switch.

[0009] Embodiments of the invention operate according to the following principle: To diagnose semiconductors and snubber circuits, a diode and the semiconductor's auxiliary voltage are used. The diode shields the gate voltage source from the HV voltage applied to the semiconductor (e.g., from the HV battery). If the HV voltage is not applied and the semiconductor is switched off, the capacitance of the snubber circuit (a capacitor) can be charged via the gate voltage source. The time for this charging process can be measured. The semiconductor can then be switched on. This creates a circuit in which the snubber capacitance discharges. The time until discharge can be measured. If a component in the diagnostic circuit does not function as desired (e.g., MOSFET, diode, snubber circuit, etc.), this would lead to altered charging or discharging times. The diagnosis would fail.If the diagnostic process is carried out as desired, it can be assumed that all components of the diagnostic circuit are OK and that the semiconductor circuit in this circuit area also functions in the HV range. The solution presented in this disclosure offers the following advantages:

[0010] The diagnostic circuit can ensure the functionality of a semiconductor fuse over the lifetime of a circuit.

[0011] Semiconductor fuses with the diagnostic circuit presented here are much faster than slow-blow fuses and can provide line protection in virtually any current range. Unlike fuses, which can only be blown once and then must be replaced, semiconductor fuses with the diagnostic circuit presented here can be reused almost any number of times after a blow.

[0012] In contrast to fuses, which cannot meet ASIL levels because they are only a thermo-mechanical component whose parameters can only be adjusted very roughly, semiconductor fuses can meet ASIL levels with the diagnostic circuit presented here.

[0013] Snubber circuits contain at least one resistor and at least one capacitor. These components can exhibit dangerous faults over their lifetime, which can be reliably detected with the diagnostic circuit presented here.

[0014] The diagnostic circuit presented here allows for the diagnosis of the switching capability of the MOSFETs and the snubber capacitances used in electronic HV semiconductor fuses, which can thus achieve the "ASIL-B" level for certain functions. The diagnostic circuit can be used for electronic fuses in both the charging path and the traction path of the vehicle and allows for reliable diagnosis of their functionality. The diagnostic circuit is particularly suitable for variants with snubber capacitance and offers a cost-effective solution for diagnosing the switching capability of the MOSFET and the snubber capacitance.

[0015] The diagnostic circuit presented here can also be used for diagnostics without ASIL-B classification in order to ensure increased reliability of the product.

[0016] Electronic switching and protection in the HV sector will replace mechanical switching with mechanical contactors and thermal protection with fuses in the future. The diagnostic circuit presented here is ideally suited for these applications to ensure the switching capability of semiconductor switches and fuses.

[0017] The diagnostic circuit presented here offers assured reliability of the fuse or switch, lower costs compared to similar products with more complex circuits for diagnosing the same function, and a smaller installation space due to the use of fewer components.

[0018] Further advantages of embodiments of the diagnostic circuit described here are the following: Semiconductor switches that are already protected from circuit energies during turn-off by a snubber circuit can be reliably diagnosed using a diode and a few additional components. This has previously only been possible with the help of an increased number of components.

[0019] The diagnostic circuit according to the invention is a simple and cost-effective way of designing the “safe isolation of currents” function in the direction of ASIL-B in a small installation space.

[0020] Using a circuit (with the MOSFETs to be tested, the snubber circuit, the gate voltage source and the diode), two functions of the product can be tested: the switching capability of the MOSFETs and the functionality of the snubber circuit.

[0021] According to a first aspect, the object described above is achieved by an electronic diagnostic circuit for functional testing of a protective circuit for an electronic fuse element in a vehicle, wherein the protective circuit comprises an RC element connected in parallel to the electronic fuse element, wherein the electronic diagnostic circuit comprises the following: a current source designed to charge the RC element in the blocking state of the electronic fuse element; and an evaluation electronic circuit designed to detect a voltage curve at the electronic fuse element; wherein the evaluation electronic circuit is designed to indicate a fault state of the protective circuit and / or the electronic fuse element in the event of a deviation of the detected voltage curve from a predetermined voltage curve.

[0022] The vehicle can be an electric vehicle with an electric drive. It can be a battery-electric vehicle, but it can also be a hybrid vehicle with an electric drive.

[0023] Such an electronic diagnostic circuit allows for reliable diagnosis of the protective circuit, e.g., a snubber circuit for a high-voltage semiconductor switch. The diagnostic circuit reliably detects whether the protective circuit is still functioning properly or whether a fault has occurred. The diagnostic circuit is particularly suitable for diagnosis while the vehicle is in operation.

[0024] According to an exemplary embodiment of the electronic diagnostic circuit, the evaluation electronics circuit is designed to determine a voltage difference of the detected voltage curve compared to the predetermined voltage curve at a predetermined time from the charging of the RC element and to indicate the error state if a threshold value is exceeded or undershot.

[0025] The diagnostic circuit provides reliable detection of fault conditions based on the deviation from a target curve that indicates the voltage curve in the normal operating state of the protective circuit and the fuse element.

[0026] According to an exemplary embodiment of the electronic diagnostic circuit, the electronic diagnostic circuit is connectable between a high-voltage input and a high-voltage output of the electronic fuse element; and the electronic diagnostic circuit comprises a diode connected in series with the power source, which is configured to shield the power source from a high-voltage voltage applied to the electronic fuse element.

[0027] The diode shields the current source or gate voltage source from the high-voltage voltage present between the high-voltage input and high-voltage output. This allows the electronic diagnostic circuit to be safely connected to the high-voltage semiconductor switch.

[0028] According to an exemplary embodiment of the electronic diagnostic circuit, the current source comprises a constant current source configured to charge the RC element with a constant increase in the voltage at the electronic fuse element.

[0029] The constant current source ensures that the RC element is charged at a constant voltage. This makes it easy to compare the voltage curve with the specified voltage curve, since both have a constant gradient.

[0030] According to an exemplary embodiment of the electronic diagnostic circuit, the current source comprises a voltage source connected in series to the constant current source, wherein the voltage source has a nominal voltage which causes the constant current source to charge the RC element up to the nominal voltage.

[0031] This voltage source is easy to implement; it can be the voltage source that is responsible for controlling the gate voltage and is already present.

[0032] According to an exemplary embodiment of the electronic diagnostic circuit, the evaluation electronics circuit is designed to detect a current path interruption in the RC element in the event of a sudden increase in the voltage curve at the electronic fuse element up to the nominal voltage.

[0033] Such a voltage waveform is characteristic of a current path interruption in the RC element. This fault condition can therefore be easily detected using the electronic diagnostic circuit.

[0034] According to an exemplary embodiment of the electronic diagnostic circuit, the evaluation electronics circuit is designed to detect a short circuit of the electronic fuse element and / or the capacitance of the RC element when the voltage curve at the electronic fuse element is limited to a forward voltage of the diode.

[0035] Such a voltage waveform is characteristic of a short circuit in the RC element. This fault condition can therefore be easily detected using the electronic diagnostic circuit.

[0036] According to an exemplary embodiment of the electronic diagnostic circuit, the evaluation electronics circuit is designed to detect a drift of the capacitance in the RC element in the event of a constant increase in the voltage at the electronic fuse element, which deviates from a predetermined constant increase in the voltage curve.

[0037] Such a voltage waveform is characteristic of capacitance drift in the RC element. This fault condition can therefore be easily detected using the electronic diagnostic circuit.

[0038] According to an exemplary embodiment of the electronic diagnostic circuit, the current source comprises a series circuit of a resistor and a voltage source having a nominal voltage, and is configured to charge the RC element up to the nominal voltage according to an RC time constant based on the resistor and the RC element.

[0039] In such an implementation, the constant current source described above can be replaced with a resistor, which is easier to implement. This is an alternative design that can also reliably detect malfunctions in the protection circuit and / or fuse element.

[0040] According to an exemplary embodiment of the electronic diagnostic circuit, the evaluation electronics circuit is designed to discharge the RC element after charging the RC element by switching on a conductive state of the electronic fuse element and to indicate a fault state of the electronic fuse element in the event of a deviation of the detected voltage curve from a predetermined voltage curve.

[0041] This also allows for efficient and reliable detection of malfunctions in the electronic fuse element or semiconductor switch, for example, a fault in the semiconductor switch during the transition from the blocking to the conducting state.

[0042] According to an exemplary embodiment of the electronic diagnostic circuit, the evaluation electronics circuit is designed to detect a fault condition of the electronic fuse element when the voltage curve at the electronic fuse element differs from a sudden decrease to a forward voltage of the diode.

[0043] When the semiconductor switch or electronic fuse element is switched on, it should short-circuit the RC element and discharge abruptly, so that only the forward voltage in the diode's forward direction remains at the measuring point. Any deviation from this behavior can be reliably detected as a malfunction of the semiconductor switch.

[0044] According to an exemplary embodiment of the electronic diagnostic circuit, the protection circuit comprises an RC snubber circuit or an RCD snubber circuit.

[0045] This offers a certain degree of flexibility in circuit design. The diagnostic circuit can reliably detect and report fault conditions for both design variants, i.e., with an RC snubber circuit or an RCD snubber circuit.

[0046] According to a second aspect, the above-described object is achieved by an electronic fuse for safely disconnecting a current path in an electric vehicle, wherein the electronic fuse comprises the following: an electronic fuse element that can be switched into the current path of the electric vehicle; a protective circuit for protecting the electronic fuse element, wherein the protective circuit comprises an RC element connected in parallel to the electronic fuse element; and an electronic diagnostic circuit according to the first aspect, which is designed to check the protective circuit for functionality.

[0047] Such an electronic fuse can be reliably monitored and diagnosed via the electronic diagnostic circuit contained therein.

[0048] According to a third aspect, the above-described object is achieved by a method for functional testing of a protective circuit for an electronic fuse element in a vehicle, wherein the protective circuit comprises an RC element connected in parallel with the electronic fuse element, wherein the method comprises the following: charging the RC element in the blocking state of the electronic fuse element by means of a current source; detecting a voltage curve at the electronic fuse element; and displaying a fault state of the protective circuit and / or the electronic fuse element in the event of a deviation of the detected voltage curve from a predetermined voltage curve.

[0049] Such a method allows for reliable diagnosis of the protective circuit for an electronic safety element, e.g., a high-voltage semiconductor switch. The diagnostic method reliably detects whether the protective circuit is still functioning properly or whether a fault has occurred. This diagnostic method is particularly suitable for diagnosis while the vehicle is in operation.

[0050] According to a fourth aspect, the above-described object is achieved by a method for functional testing of a fuse element in an electric vehicle, wherein the protective circuit comprises an RC element connected in parallel with an electronic fuse element, the method comprising the following: discharging the RC element by switching the fuse element into a conductive state; detecting a voltage curve at the electronic fuse element; and indicating a fault state of the fuse element in the event of a deviation of the detected voltage curve from a predetermined voltage curve.

[0051] This allows a malfunction of the electronic fuse element or the semiconductor switch to be detected efficiently and reliably, for example a fault in the semiconductor switch during the transition from the blocking to the conducting state.

[0052] This disclosure describes high-voltage (HV) vehicles and HV batteries. In order to drive high-voltage vehicles at a power level acceptable to the vehicle owner, the electric motors must operate at very high voltages. Systems and components in motor vehicles that operate above 60 V DC are referred to as high-voltage (HV) systems or HV vehicles. Voltages exceeding 60 V DC can have dangerous effects on the human body. In current HV vehicles, the HV system voltages range between 250 V and 1000 V DC. The high-voltage systems of most current electric cars operate at a voltage level of around 400 volts. Short character description

[0053] The invention is described in more detail below using exemplary embodiments and the figures. They show: Fig. 1 shows a circuit diagram of an electronic fuse 100 with an electronic diagnostic circuit 110 according to the invention according to an embodiment; Fig. 2a a graphical representation of an exemplary predetermined voltage curve 121e at a measuring point of the electronic diagnostic circuit 110 from Fig. 1; Fig. 2b a graphical representation of a detected voltage curve 121a at the measuring point of the electronic diagnostic circuit 110 from Fig. 1 in case of error; Fig. 2c a graphical representation of a detected voltage curve 121b at the measuring point of the electronic diagnostic circuit 110 from Fig. 1 in case of error; Fig. 2d a graphical representation of two detected voltage curves 121c, 121d in the event of a fault compared to the specified voltage curve 121e at the measuring point of the electronic diagnostic circuit 110 from Fig. 1; Fig. 3 is a circuit diagram of an electronic fuse 300 with electronic diagnostic circuit 110 according to the invention according to an alternative embodiment; Fig. 4 a graphical representation of an exemplary predetermined voltage curve 121e at a measuring point of the electronic diagnostic circuit 110 from Fig. 3; Fig. 5 is a circuit diagram of an RCD snubber circuit 500 as an example of a protection circuit for an electronic fuse element according to an embodiment; and Fig. 6 a system diagram of a charging system 600 for charging a battery of a battery-electric vehicle.

[0054] The figures are merely schematic representations and serve only to illustrate the invention. Identical or equivalent elements are provided with the same reference numerals throughout.

[0055] In the following detailed description, reference is made to the accompanying drawings, which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. The following detailed description, therefore, is not to be taken in a limiting sense. Further, it is to be understood that the features of the various embodiments described herein may be combined with one another unless specifically indicated otherwise.

[0056] The aspects and embodiments are described with reference to the drawings, where like reference numerals generally refer to like elements. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of one or more aspects of the invention. However, it may be apparent to one skilled in the art that one or more aspects or embodiments may be practiced with a lesser level of specific detail. In other instances, well-known structures and elements are shown in schematic form to facilitate describing one or more aspects or embodiments. It is understood that other embodiments may be utilized and structural or logical changes may be made without departing from the concept of the present invention.

[0057] Fig. 1 shows a circuit diagram of an electronic fuse 100 with an electronic diagnostic circuit 110 according to the invention according to an embodiment.

[0058] The electronic diagnostic circuit 110 is used to test the function of a protective circuit 120 (e.g. a snubber circuit) for an electronic fuse element M1 (e.g. a semiconductor switch, for example a MOSFET) in a vehicle, wherein the protective circuit 120 comprises an RC element R1, C1 connected in parallel to the electronic fuse element M1.

[0059] The vehicle can be an electric vehicle with an electric drive. It can be a battery-electric vehicle, but it can also be a hybrid vehicle with an electric drive.

[0060] The electronic diagnostic circuit 110 comprises: a current source 111, which is designed to charge the RC element R1, C1 in the blocking state of the electronic fuse element M1; and an evaluation electronic circuit 112, which is designed to generate a voltage curve 121 (as shown by way of example in the Fig. 2b to 2d) on the electronic security element M1.

[0061] The evaluation electronics circuit 112 is designed to detect a deviation of the detected voltage curve 121 from a predetermined voltage curve 121e (as shown for example in Fig. 2a) to indicate a fault condition of the protection circuit 120 and / or the electronic fuse element M1.

[0062] The evaluation electronics circuit 112 can be designed to determine a voltage difference of the detected voltage curve 121 compared to the predetermined voltage curve 121e at a predetermined time from the charging of the RC element R1, C1 and to indicate the error state if a threshold value is exceeded or undershot.

[0063] The electronic diagnostic circuit 110 can be connected or switched between a high-voltage input HV_INPUT and a high-voltage output HV_OUTPUT of the electronic fuse element M1, as shown in Fig. 1 shown.

[0064] The electronic diagnostic circuit 110 may comprise a diode D1 connected in series with the current source 111, which is designed to shield the current source 111 from a high-voltage voltage applied to the electronic fuse element M1.

[0065] The current source 111 may comprise a constant current source I1, as shown in Fig. 1, which may be designed to charge the RC element R1, C1 under a constant increase in the voltage at the electronic fuse element M1.

[0066] The current source 111 may comprise a voltage source V1, which as in Fig. 1, can be connected in series to the constant current source I1, wherein the voltage source V1 has a nominal voltage which causes the constant current source I1 to charge the RC element R1, C1 up to the nominal voltage.

[0067] The evaluation electronics circuit 112 can, for example, be designed to react to a sudden increase in the voltage curve 121a at the electronic fuse element M1, as in Fig. 2b, to detect a current path interruption in the RC element R1, C1 up to the nominal voltage.

[0068] The evaluation electronics circuit 112 can be designed, with a limitation of the voltage curve 121b at the electronic fuse element M1, as in Fig. 2c, except for a forward voltage of the diode D1, to detect a short circuit of the electronic fuse element M1 and / or the capacitance of the RC element R1, C1.

[0069] The evaluation electronics circuit 112 can be designed, with a constant increase in the voltage 121c, 121d at the electronic fuse element M1, as in Fig. 2d, which assumes a given constant increase in the voltage curve 121e (see Fig. 2a), to detect a drift of the capacitance C1 in the RC element R1, C1 or the snubber circuit.

[0070] The evaluation electronics circuit 112 can be designed to discharge the RC element R1, C1 after charging the RC element R1, C1 by switching on a conductive state of the electronic fuse element M1 and in case of a deviation of the detected voltage curve 121 (see Fig. 2b to 2d) compared to a given voltage curve 121e (see Fig. 2a) to indicate a fault condition of the electronic fuse element M1.

[0071] The evaluation electronics circuit 112 can be designed, with a voltage curve 121 (see Fig. 2b to 2d) on the electronic fuse element M1, which differs from a sudden decrease to a forward voltage of the diode D1, to detect a fault condition of the electronic fuse element M1.

[0072] The protection circuit 120 may be an RC snubber circuit, for example as shown in Fig. 1 and Fig. 3, or an RCD snubber circuit 500, for example as shown in Fig. 5 include.

[0073] Fig. 1 thus represents an electronic fuse 100 for safely disconnecting a current path in an electric vehicle, wherein the electronic fuse 100 comprises the following: an electronic fuse element M1 that can be switched into the current path of the electric vehicle; a protective circuit 120 for protecting the electronic fuse element M1, wherein the protective circuit 120 comprises an RC element R1, C1 connected in parallel to the electronic fuse element M1; and an electronic diagnostic circuit 110 as described above, which is designed to check the protective circuit 120 for functionality.

[0074] With the help of the Fig. 1, it is possible to test the proper functioning of an RC snubber used to protect power semiconductors in an electronic fuse.

[0075] At the beginning of a driving cycle, before both or the second main contactor are closed, a voltage source V1 and a constant current source I1 are used, as shown in Fig. 1, the RC snubber R1, C1 is charged via the diode D1.

[0076] Diode D1 may be necessary to block the HV battery voltage from the evaluation electronics 112 when the MOSFETs are blocked and the HV battery voltage is applied.

[0077] MOSFET M1 is switched to the off state via the gate drive. Only one MOSFET is shown as an example, but several power semiconductors (e.g., IGBTs) can also be connected in parallel to enable higher current carrying capacity.

[0078] The source voltage can be freely selected (e.g., 5V, 12V, etc.). In this case, 20V was used; this corresponds to the gate drive voltage of the SiC MOSFETs and offers better resolution than, for example, 5V.

[0079] For example, the constant current should be in the range of 300µA to 3mA.

[0080] The voltage curve at the point marked with measuring point in Fig. 1 is fed to an evaluation electronics 112 and the state of the snubber 120 is diagnosed.

[0081] The evaluation electronics 112 can comprise or be a discrete circuit or a µC with analog-to-digital converter (ADC).

[0082] If the RC-Snubber 120 is working properly, you will see a curve like in Fig. 2a. If the resistor R1 or the capacitor C1 is interrupted, the curve will be as shown in Fig. 2b. If the capacitor C1 is short-circuited, the curve will be as shown in Fig. 2c. If the capacitor C1 drifts (for example >=50% of the nominal value), the curves shown in Fig. 2d, from which it can be seen that with a larger capacity (positive drift) the slope of curve 121d is flatter and with a smaller capacity (negative drift) the slope of curve 121c is steeper.

[0083] According to DIN EN 61709, a short circuit or drift (>=50%) of the resistance does not need to be diagnosed or is excluded due to the component.

[0084] The above Fig. The circuit described in Figure 1 can also be used to test the switching capability of the MOSFET. When the MOSFET is switched on via the gate drive, the voltage at the measuring point should drop to a voltage value equal to the constant current I1 times the MOSFET's on-state resistance plus the forward voltage of diode D1.

[0085] After checking the turn-on capability, the MOSFET can be turned off via the gate drive, and the turn-off capability can be diagnosed. If the MOSFET's turn-off capability is present, the RC snubber 120 can be charged, and the behavior described above will occur.

[0086] If the charge level of the capacitor C1 is undefined before the start of a driving cycle and is already partially charged, the charging process can be interrupted during the shutdown process according to Fig. 2a (time >=30ms) can be used for the diagnosis of the RC snubber 120.

[0087] In principle, this diagnostic circuit 110 can also be connected to an RCD snubber 500, as in Fig. 5. However, this type of protection circuit cannot diagnose all faults. Without further modifications, only a capacitor fault can be diagnosed.

[0088] The electronic fuse 100 described here can be used in battery electric vehicles (BEV). Possible installation locations are Fig. 6 marked F1, F2 and F3.

[0089] Fig. 2a shows a graphical representation of an exemplary predetermined voltage curve 121e at a measuring point of the electronic diagnostic circuit 110 from Fig. 1.

[0090] After starting the charging (at about 1ms) of the RC element R1, C1 from Fig. 1, the RC element is constantly charged via the current source 111. After a time of approximately 5 ms, the RC element is fully charged and the voltage V at the RC element corresponds to the voltage V1 of the current source 111.

[0091] At a time of 10 ms, the semiconductor switch M1 is closed, and the voltage V across the RC element drops abruptly to the forward voltage of diode D1, where it remains until the RC element is charged again at a time of 20 ms. After that, the RC element is again constantly charged via current source 111. At a time of approximately 24 ms, the RC element is fully charged, and the voltage V across the RC element corresponds to the voltage V1 of current source 111.

[0092] The curve of the Fig. 2a represents the target value, i.e., it corresponds to the specified voltage curve 121e at the point marked “measuring point” of the electronic diagnostic circuit 110.

[0093] Fig. 2b shows a graphical representation of a detected voltage curve 121a at the measuring point of the electronic diagnostic circuit 110 from Fig. 1 in case of error.

[0094] After starting the charging (at about 1ms) of the RC element R1, C1 from Fig. 1, the voltage V at the RC element rises sharply to the voltage V1 of the current source 111. This curve 121a corresponds to a fault in which a current path in the protection circuit 120 is open or there is an interruption in the current path. This can be triggered, for example, by a defective C1 or R1, in which C1 and / or R1 have an open current path, for example, due to a defective solder connection or the like.

[0095] At a time of 10 ms, semiconductor switch M1 is closed, and the voltage V across the RC element drops abruptly to the forward voltage of diode D1, where it remains until the RC element is charged again at a time of 20 ms. After that, the RC element is charged again via current source 111, which is associated with the same sudden increase in the voltage V across the RC element. The fault condition still exists.

[0096] The curve 121a of the Fig. 2b can be compared with curve 121e of the Fig. 2a to determine the error case of the Fig. 2b.

[0097] Fig. 2c shows a graphical representation of a detected voltage curve 121b at the measuring point of the electronic diagnostic circuit 110 from Fig. 1 in case of error.

[0098] After starting the charging (at about 1ms) of the RC element R1, C1 from Fig. 1, there is a sudden increase in the voltage V at the RC element, but only up to the forward voltage of diode D1, i.e., up to approximately 0.75 V. This curve 121b corresponds to a fault in which a short-circuited current path exists in the protection circuit 120. This can be triggered, for example, by a short circuit at C1 or R1, in which C1 and / or R1 have a short-circuited current path, so that charging up to the voltage V1 of the current source 111 is no longer possible.

[0099] Even recharging the RC element R1, C1 does not improve the situation. The fault condition persists.

[0100] Curve 121b of the Fig. 2c can be compared with curve 121e of the Fig. 2a to determine the error case of the Fig. 2c.

[0101] Fig. Figure 2d shows a graphical representation of two detected voltage curves 121c, 121d in the event of a fault compared to the specified voltage curve 121e at the measuring point of the electronic diagnostic circuit 110 from Fig. 1.

[0102] After starting the charging (at about 1ms) of the RC element R1, C1 from Fig. 1, there is a constant increase in the voltage V across the RC element up to the voltage V1 of the current source 111. However, the gradient of this increase differs for curves 121c and 121d from the gradient of the specified curve 121e of the voltage V. These two curves 121c and 121d each correspond to a fault case in which the capacitance C1 drifts from its nominal value. For curve 121d, there is a positive drift of greater than 50%, while for curve 121c, there is a negative drift of less than -50%. If the capacitance is larger, the increase is flatter, as can be seen in curve 121d. If the capacitance is smaller, the increase is steeper, as can be seen in curve 121c.

[0103] At a time of 10 ms, semiconductor switch M1 is closed, and the voltage V across the RC element drops abruptly to the forward voltage of diode D1, where it remains until the RC element is charged again at a time of 20 ms. After that, the RC element is charged again via current source 111, which is associated with the same drift-prone increase in the voltage V across the RC element. The fault condition still exists.

[0104] Curves 121c and 121d of the Fig. 2d can be compared with curve 121e of the Fig. 2d or the Fig. 2a to determine the error case of the Fig. 2d to determine.

[0105] Fig. 3 shows a circuit diagram of an electronic fuse 300 with electronic diagnostic circuit 110 according to the invention according to an alternative embodiment.

[0106] As in the above Fig. 1 described electronic diagnostic circuit 110 also serves the Fig. 3 shows an electronic diagnostic circuit 110 for functional testing of a protective circuit 120 (e.g. a snubber circuit) for an electronic fuse element M1 (e.g. a semiconductor switch, for example a MOSFET) in a vehicle, wherein the protective circuit 120 comprises an RC element R1, C1 connected in parallel to the electronic fuse element M1.

[0107] The electronic diagnostic circuit 110 comprises: a current source 111 configured to charge the RC element R1, C1 in the blocking state of the electronic fuse element M1; and an evaluation electronic circuit 112 configured to detect a voltage waveform 121 at the electronic fuse element M1.

[0108] The evaluation electronics circuit 112 is designed to detect a deviation of the detected voltage curve 121 from a predetermined voltage curve 121e (as shown for example in Fig. 4) to indicate a fault condition of the protection circuit 120 and / or the electronic fuse element M1. In the event of a short circuit or an open circuit, the curve corresponds to that of the Fig. 2b and 2c respectively. In case of drift, a characteristic curve results, which, however, does not correspond to the curves 121c and 121d from Fig. 2d. Rather, the increase in this case is not linear but exponential, as described in more detail below.

[0109] The current source 111 can be used here in the embodiment of Fig. 3 comprise a series circuit of a resistor R5 and a voltage source V1 having a nominal voltage, and be designed to charge the RC element R1, C1 up to the nominal voltage according to an RC time constant based on the resistor R5 and the RC element R1, C1.

[0110] The evaluation electronics circuit 112 can also be Fig. 3 be designed, after charging the RC element R1, C1, to discharge the RC element R1, C1 by switching on a conductive state of the electronic fuse element M1 and in case of a deviation of the detected voltage curve 121 from a predetermined voltage curve 121e (see Fig. 4) to indicate a fault condition of the electronic fuse element M1.

[0111] In contrast to the given voltage curve 121e from Fig. 2a, the given voltage curve 121e differs according to Fig. 4 in that it does not increase linearly, but according to a time constant which is determined from the resistance R5 of the current source 111 and the resistance R1 of the protection circuit 120 as well as the capacitance C1 of the protection circuit 120, in particular according to the formula τ=(R1+R5) C1.

[0112] The electronic diagnostic circuit 110 of the Fig. 3, the evaluation electronics circuit 112 can be designed to detect a fault condition of the electronic fuse element M1 in the case of a voltage curve 121 at the electronic fuse element M1 which differs from a sudden decrease to a forward voltage of the diode D1.

[0113] The protection circuit 120 can also in this embodiment of the Fig. 3 an RC snubber circuit or an RCD snubber circuit 500 (see Fig. 5) include.

[0114] Fig. 3 thus represents a possible modification of the diagnostic circuit Fig. 1. The constant current source I1 can be replaced by a resistor R5. If it is functioning properly, the curve is as follows: Fig. 4. By replacing I1, an exponential charging curve results instead of a linear charging process. This also results in characteristic curve progressions for evaluation in the event of a fault.

[0115] The electronic fuse 300 described here can be used in battery electric vehicles (BEV). Possible installation locations are in Fig. 6 marked F1, F2 and F3.

[0116] Fig. 4 shows a graphical representation of an exemplary predetermined voltage curve 121e at a measuring point of the electronic diagnostic circuit 110 from Fig. 3.

[0117] After starting the charging (at about 1ms) of the RC element R1, C1 from Fig. 3, the RC element is exponentially charged via the current source 111 according to a time constant τ = (R1+R5) C1. At a time of approximately 4 ms, the RC element is fully charged, and the voltage V across the RC element corresponds to the voltage V1 of the current source 111.

[0118] At a time of 10 ms, semiconductor switch M1 is closed, and the voltage V across the RC element drops abruptly to the forward voltage of diode D1, where it remains until the RC element is charged again at a time of 20 ms. After that, the RC element is exponentially charged again via current source 111 according to the time constant τ = (R1+R5) C1 specified above. At a time of approximately 23 ms, the RC element is fully charged, and the voltage V across the RC element corresponds to the voltage V1 of current source 111.

[0119] The curve of the Fig. 4 represents the setpoint, thus corresponding to the specified voltage curve 121e at the point marked “measuring point” of the electronic diagnostic circuit 110 in the embodiment according to Fig. 3.

[0120] Fig. 5 shows a circuit diagram of an RCD snubber circuit 500 as an example of a protection circuit for an electronic fuse element according to an embodiment.

[0121] The RCD snubber circuit 500 comprises a parallel circuit of a resistor R2 with a series circuit of a resistor R3 and a diode D2. A capacitor C2 is connected in series with the parallel circuit.

[0122] A fault of C2 can be efficiently diagnosed using the electronic diagnostic circuit 100, 300 described above.

[0123] Fig. 6 shows a system diagram of a charging system 600 for charging a battery of a battery-electric vehicle.

[0124] The charging system 600 includes electrical and electronic components of the vehicle, shown on the left, and electrical and electronic components of the charging infrastructure, shown on the right. The charging infrastructure includes a charging station 620 for charging the vehicle's battery 640, to which a capacitor C1 is connected in parallel and an inductor L1 is connected in series.

[0125] On the vehicle side, the electrical and electronic components of the vehicle include a battery 640 for driving the vehicle or an HV storage device, which is connected in series with an inductance L3 at a first pole and an inductance L4 at a second pole of the battery in the charging current path 630.

[0126] An S-Box 610 (switch box) is connected to the charging path 630 in the vehicle, enabling charging of the battery 640. The S-Box 610 is also connected to a traction path and one or more auxiliary consumer paths. The S-Box 610 controls the charging of the battery 640 and the operation of the traction path and the auxiliary consumer paths via the battery 640. Switches for connecting to the charging infrastructure are not shown.

[0127] The traction path includes an electric motor 650, to which a capacitor C2 is connected in parallel and an inductance L2 is connected in series.

[0128] The auxiliary load paths comprise one or more electronic components connected in parallel, such as an electric heater with a PTC (positive temperature coefficient conductor) 651 and KMV (refrigerant compressor) 652, to which a capacitor C3 is connected in parallel and an inductor L5 is connected in series.

[0129] The S-Box 610 includes a charging infrastructure-side fuse F1, which may be a semiconductor-based fuse with inventive electronic diagnostic circuitry 100, 300, as presented in this disclosure. The S-Box 610 further includes a battery-side fuse F3, an inductance L S-Box and a circuit with parallel switches S 31 and S 32, which are connected in series with the fuse F1 in the charging current path 630. The battery-side fuse F3 can also be designed as a semiconductor-based fuse with the inventive electronic diagnostic circuit 100, 300. A second circuit with switches S4 and S2 branches between the fuse F1 and the inductance L S-Box to connect the traction path and the auxiliary consumer paths to the battery 640 when the vehicle is disconnected from the charging infrastructure. The auxiliary consumer paths are connected to the second circuit via a fuse F2. The fuse F2 can also be embodied as a semiconductor-based fuse with the electronic diagnostic circuit 100, 300 according to the invention, in which case the fuse does not serve to disconnect the charging path 130, but rather to disconnect the current path between the battery 640 and the auxiliary consumers 651, 652.

[0130] The S-Box 610 also includes a capacity C S-Box, which is connected in parallel to the charging infrastructure.

[0131] The disclosure also relates to a method for functional testing of a protective circuit 120 for an electronic fuse element M1 in a vehicle, wherein the protective circuit 120 comprises an RC element R1, C1 connected in parallel to the electronic fuse element M1, as in Fig. 1 or Fig. 3 shown.

[0132] Such a procedure includes the following steps: 1) Charging the RC element R1, C1 in the blocking state of the electronic fuse element M1 by means of a current source 111; 2) Recording a voltage curve 121b, 121c, 121d (see Fig. 2b to 2d) on the electronic security element M1; and 3) Indication of a fault condition of the protection circuit 120 and / or the electronic fuse element M1 in the event of a deviation of the detected voltage curve 121b, 121c, 121d from a predetermined voltage curve 121e (see Fig. 2a and Fig. 4).

[0133] Furthermore, the disclosure also relates to a method for functional testing of a fuse element M1 in an electric vehicle, wherein the protective circuit 120 comprises an RC element R1, C1 connected in parallel to an electronic fuse element M1, as in Fig. 1 or Fig. 3 shown.

[0134] Such a procedure includes the following steps: 1) Discharging the RC element R1, C1 by switching the fuse element M1 into a conductive state; 2) Recording a voltage curve 121b, 121c, 121d (see Fig. 2b to 2d) on the electronic security element M1; and 3) Indication of a fault condition of the fuse element M1 in the event of a deviation of the detected voltage curve 121b, 121c, 121d from a predetermined voltage curve 121e (see Fig. 2a and Fig. 4). LIST OF REFERENCE SYMBOLS 100 electronic fuses according to one design 110 electronic diagnostic circuit 120 Protection circuit with RC element or snubber circuit M1 electronic fuse element or semiconductor fuse R1 resistance of the RC element C1 capacitor of the RC element 111 Power source 112 Evaluation electronics circuit 121 a / b / c / d / e or 121 recorded voltage curves 121e specified voltage curve HV_INPUT High-voltage input of the electronic fuse element HV_OUTPUT High-voltage output of the electronic fuse element D1 diode I1 constant current source V1 voltage source V voltage at the protection circuit 120 300 electronic fuse according to an alternative design 500 RCD snubber circuit 600 charging system 610 S-Box 620 charging stations 640 battery or HV storage 650 electric motor or traction 651 Auxiliary consumer, PTC resistor 652 secondary consumers KMV 630 Charging current path

Claims

[1] Electronic diagnostic circuit (110) for functional testing of a protective circuit (120) for an electronic fuse element (M1) in a vehicle, wherein the protective circuit (120) comprises an RC element (R1, C1) connected in parallel to the electronic fuse element (M1), wherein the electronic diagnostic circuit (110) comprises the following: a current source (111) designed to charge the RC element (R1, C1) in the blocking state of the electronic fuse element (M1); and an evaluation electronics circuit (112) which is designed to detect a voltage curve (121) at the electronic fuse element (M1); wherein the evaluation electronics circuit (112) is designed to indicate a fault condition of the protective circuit (120) and / or the electronic fuse element (M1) in the event of a deviation of the detected voltage curve (121) from a predetermined voltage curve (121e). [2] Electronic diagnostic circuit (110) according to claim 1, wherein the evaluation electronic circuit (112) is designed to determine a voltage difference of the detected voltage curve (121) compared to the predetermined voltage curve at a predetermined time from the charging of the RC element (R1, C1) and to indicate the error state if a threshold value is exceeded or undershot. [3] electronic diagnostic circuit (110) according to claim 1 or 2, wherein the electronic diagnostic circuit (110) is switchable between a high-voltage input (HV_INPUT) and a high-voltage output (HV_OUTPUT) of the electronic fuse element (M1); and wherein the electronic diagnostic circuit (110) comprises a diode (D1) connected in series with the current source (111) and designed to shield the current source (111) from a high-voltage applied to the electronic fuse element (M1). [4] Electronic diagnostic circuit (110) according to claim 3, wherein the current source (111) comprises a constant current source (I1) which is designed to charge the RC element (R1, C1) with a constant increase in the voltage at the electronic fuse element (M1). [5] Electronic diagnostic circuit (110) according to claim 4, wherein the current source (111) comprises a voltage source (V1) connected in series to the constant current source (I1), the voltage source (V1) having a nominal voltage which causes the constant current source (I1) to charge the RC element (R1, C1) up to the nominal voltage. [6] Electronic diagnostic circuit (110) according to claim 5, wherein the evaluation electronic circuit (112) is designed to detect a current path interruption in the RC element (R1, C1) in the event of a sudden increase in the voltage curve (121a) at the electronic fuse element (M1) up to the nominal voltage. [7] Electronic diagnostic circuit (110) according to one of claims 3 to 6, wherein the evaluation electronic circuit (112) is designed to detect a short circuit of the electronic fuse element (M1) and / or the capacitance of the RC element (R1, C1) when the voltage curve (121b) at the electronic fuse element (M1) is limited to a forward voltage of the diode (D1). [8] Electronic diagnostic circuit (110) according to one of claims 4 to 7, wherein the evaluation electronic circuit (112) is designed to detect a drift of the capacitance (C1) in the RC element (R1, C1) in the case of a constant increase in the voltage (121c, 121d) at the electronic fuse element (M1), which deviates from a predetermined constant increase in the voltage curve (121e). [9] Electronic diagnostic circuit (110) according to claim 3, wherein the current source (111) comprises a series circuit of a resistor (R5) and a voltage source (V1) having a nominal voltage, and is designed to charge the RC element (R1, C1) up to the nominal voltage according to an RC time constant based on the resistor (R5) and the RC element (R1, C1). [10] Electronic diagnostic circuit (110) according to one of claims 3 to 9, wherein the evaluation electronic circuit (112) is designed, after charging the RC element (R1, C1), to discharge the RC element (R1, C1) by switching on a conductive state of the electronic fuse element (M1) and to indicate a fault state of the electronic fuse element (M1) in the event of a deviation of the detected voltage curve (121) from a predetermined voltage curve (121e). [11] Electronic diagnostic circuit (110) according to claim 10, wherein the evaluation electronic circuit (112) is designed to detect a fault condition of the electronic fuse element (M1) in the case of a voltage curve (121) at the electronic fuse element (M1) which differs from a sudden decrease to a forward voltage of the diode (D1). [12] Electronic diagnostic circuit (110) according to one of the preceding claims, wherein the protection circuit (120) comprises an RC snubber circuit or an RCD snubber circuit (500). [13] electronic fuse (100, 300) for safely disconnecting a current path in an electric vehicle, the electronic fuse (100, 300) comprising: an electronic fuse element (M1) that can be switched into the current path of the electric vehicle; a protection circuit (120) for protecting the electronic fuse element (M1), wherein the protection circuit (120) comprises an RC element (R1, C1) connected in parallel to the electronic fuse element (M1); and an electronic diagnostic circuit (110) according to one of the preceding claims, which is designed to check the protective circuit (120) for functionality. [14] Method for functional testing of a protective circuit (120) for an electronic fuse element (M1) in a vehicle, wherein the protective circuit (120) comprises an RC element (R1, C1) connected in parallel to the electronic fuse element (M1), the method comprising the following: Charging the RC element (R1, C1) in the blocking state of the electronic fuse element (M1) by means of a current source (111); Detecting a voltage curve (121) at the electronic fuse element (M1); and Displaying a fault condition of the protective circuit (120) and / or the electronic fuse element (M1) in the event of a deviation of the detected voltage curve (121) from a predetermined voltage curve (121e). [15] Method for functional testing of a fuse element (M1) in an electric vehicle, wherein the protective circuit (120) comprises an RC element (R1, C1) connected in parallel to an electronic fuse element (M1), the method comprising the following: Discharging the RC element (R1, C1) by switching the fuse element (M1) into a conductive state; Detecting a voltage curve (121) at the electronic fuse element (M1); and Indicating a fault condition of the fuse element (M1) in the event of a deviation of the detected voltage curve (121) from a predetermined voltage curve (121e).

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