Semiconductor fuse with detection circuit for detecting gate threshold voltage drift

Abstract

Semiconductor fuse (200) for safely disconnecting an electrical load (112) from a power supply source (111) for a battery-electric vehicle, wherein the semiconductor fuse (200) comprises the following: at least one semiconductor switching element (211) that can be switched between the power supply source (111) and the electrical load (112), wherein the at least one semiconductor switching element (211) has a gate control terminal (212) for switching on and off a power path (130) of the at least one semiconductor switching element (211) in order to switch the electrical load (112) to the power supply source (111) or to disconnect it from the power supply source (111); a driver circuit (221) configured to apply a driver voltage (223) to the gate control terminal (212) of the at least one semiconductor switching element (211), which is smaller or larger than a predetermined gate threshold voltage of the at least one semiconductor switching element (211); a detection circuit (222) configured to determine the resistance of the power path (130) of the at least one semiconductor switching element (211) and to detect a drift of the gate threshold voltage based on the resistance of the power path (130); and a control (220) configured to indicate a malfunction of the at least one semiconductor switching element (211) upon detection of a drift of the gate threshold voltage, wherein the detection circuit (222) is connected in parallel to the at least one semiconductor switching element (211) and is configured to induce a current in the power path (130) of the at least one semiconductor switching element (211), wherein the detection circuit (222) includes a detection resistor (R2) and is configured to guide the current impressed into the power path (130) of the at least one semiconductor switching element (211) through the detection resistor (R2), wherein the detection circuit (222) comprises a voltage source (V2) and a current source (I1) connected in series with the detection resistor (R2) and configured to impress the current into the power path (130); or wherein the detection circuit (222) comprises a voltage source (V2) and an auxiliary resistor (R1) connected in series with the detection resistor (R2) and configured to impress the current into the power path (130).

Description

Technical field

[0001] The present invention relates to the field of electrical and electronic fuses for interrupting overcurrents in battery-electric vehicles. In particular, the invention relates to a semiconductor fuse with a detection circuit for detecting a drift of the gate threshold voltage, especially based on a diagnosis of a gate threshold voltage drift using the detection circuit. State of the art

[0002] In high-voltage (HV) applications, particularly battery-electric vehicles, an electrical fuse, especially a cartridge fuse, is typically used to interrupt sustained overcurrents. Before a critical current is reached, the cartridge fuse melts due to the heat generated, thus interrupting the current. Alternatively, an electronic fuse with semiconductors can be used. In an electronic fuse, the overcurrent must first be detected before the interruption process can be initiated. This requires measuring and evaluating the overcurrent flowing through the electronic fuse element. Various methods exist for this evaluation, which trigger the interruption based on calculating the conductor temperature or the average current.However, it has been shown that such a shutdown is too slow and that sudden short-circuit events can damage or destroy the electronic fuse. Furthermore, it cannot guarantee safety requirements in the high-voltage range, such as those required for battery-electric vehicles.

[0003] Publication JP 2016 - 5 289 A concerns a power conversion device with a deterioration diagnostic function.

[0004] Document US 2008 / 0 290 911 A1 concerns the control of discrete or integrated power MOSFETs in switching applications such as DC / DC conversion and especially switching at high frequencies.

[0005] The publication DE 102017 011 227 A1 concerns a control system for an electrically assisted power steering system. Description of the invention

[0006] One object of the invention is therefore to create a concept for safely switching off overcurrents in battery-electric vehicles, in which the disadvantages described above do not occur.

[0007] The problem is solved by the subject matter of the independent claims. Advantageous embodiments 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 semiconductor-based fuse, also referred to as a digital fuse ("dFuse"), which reliably detects critical overcurrents, such as short-circuit currents, and can interrupt them faster than contactors, fuse links, or pyro-fuses. To ensure safe interruption with the semiconductor fuse according to ASIL B in the HV range, diagnostics are necessary for the semiconductor, depending on the technology, such as SIC-MOSFET, IGBT, SI-MOSFET, etc. One such diagnostic method is gate threshold voltage drift detection using a detection circuit, as presented in this disclosure. This ensures that no unintentional switching on occurs and that safe switching off is guaranteed in the event of a short circuit.

[0009] The gate threshold voltage drift detection presented here works as follows: Before the main contactors, or depending on the installation location of the dFuse, the second main contactor, releases the entire system, a voltage is applied to the control terminal (gate in the case of a MOSFET) that is smaller than the typical gate threshold voltage, for example 4V.

[0010] Using the detection circuit (which also corresponds to a modified DESAT circuit), it is then checked whether the power path (drain-source) has a high impedance. This is the case if, at measuring points TP1 or TP2, as in Fig. 3. In more detail, a voltage is detected using a comparator, which is approximately the value of V2 (see Fig. 3) possesses. If this is the case, no drift occurred, and normal operation can continue after this diagnosis. This diagnosis ensures shutdown during further operation. If measuring point TP2 is used, it is even possible to determine whether the drain-source resistance is greater or less than R2 (see Fig. 3) is (realization with a current source as shown in Fig. 3).

[0011] The gate threshold voltage drift detection presented here can be used with all types of electronic fuses or semiconductor fuses in both low-voltage (LV) and high-voltage (HV) applications. With this gate threshold voltage drift detection, an HV semiconductor fuse can be provided that meets ASIL-B requirements or higher for safe disconnection. Conventional products cannot meet these requirements.

[0012] According to a first aspect, the problem described above is solved by a semiconductor fuse for safely disconnecting an electrical load from a power supply source for a battery-electric vehicle, wherein the semiconductor fuse comprises: at least one semiconductor switching element that can be switched between the power supply source and the electrical load, wherein the at least one semiconductor switching element has a gate control terminal for switching on and off a power path of the at least one semiconductor switching element in order to connect the electrical load to or disconnect it from the power supply source; a driver circuit configured to apply a driver voltage to the gate control terminal of the at least one semiconductor switching element, which is lower than a predetermined gate threshold voltage of the at least one semiconductor switching element;a detection circuit configured to determine the resistance of the power path of the at least one semiconductor switching element and to detect a drift of the gate threshold voltage based on the resistance of the power path; and a control circuit configured to indicate a malfunction of the at least one semiconductor switching element upon detection of a drift of the gate threshold voltage.

[0013] Upon detecting a drift in the gate threshold voltage, the control system can diagnose a malfunction of at least one semiconductor switching element and quickly switch off that semiconductor switching element so that it can be replaced.

[0014] Such a semiconductor fuse offers the technical advantage of reliable diagnostics, based on gate threshold voltage drift detection, to determine whether the semiconductor switching element is still functional and can reliably switch off. The semiconductor fuse ensures that no unintentional switch-on occurs and that safe shutdown is guaranteed in the event of a short circuit.

[0015] The semiconductor fuse can thus ensure protective functions in accordance with ASIL requirements.

[0016] The gate threshold voltage of a field-effect transistor (FIT) or MOSFET is the gate-source voltage at which a significant current flows relative to the maximum drain current. The gate threshold voltage can be found in the transistor's datasheet. The power path of the semiconductor switching element in a field-effect transistor is the path between the drain and source terminals.

[0017] According to an exemplary embodiment of the semiconductor fuse, the at least one semiconductor switching element has a drain terminal and a source terminal, between which the power path of the at least one semiconductor switching element is formed, wherein the resistance of the power path corresponds to a resistance between the drain terminal and the source terminal.

[0018] This offers the technical advantage that the resistance between the drain terminal and the source terminal can be accurately determined by voltage measurements, allowing gate threshold voltage drift detection to be performed quickly and precisely.

[0019] According to an exemplary embodiment of the semiconductor fuse, the gate control terminal of the at least one semiconductor switching element has a gate resistor; wherein the driver circuit is configured to apply the driver voltage to the gate resistance of the gate control terminal; and wherein the detection circuit is configured to determine the resistance of the power path as a function of a gate voltage at the gate control terminal.

[0020] This offers the technical advantage that the detection of the drift of the gate threshold voltage can be performed synchronously with the application of the driver voltage to the gate resistor, and thus the resistance of the power path can be precisely determined.

[0021] The detection circuit is connected in parallel to the at least one semiconductor switching element and is designed to induce a current in the power path of the at least one semiconductor switching element.

[0022] This offers the technical advantage that the resistance of the power path can be easily determined via the current impressed into the power path, and thus a drift of the gate threshold voltage can be efficiently detected.

[0023] The detection circuit includes a detection resistor and is designed to guide the current impressed into the power path of the at least one semiconductor switching element through the detection resistor.

[0024] This offers the technical advantage that the detection resistor can be used to provide measuring points for a voltage measurement, from which the resistance of the power path can be determined and thus a drift of the gate threshold voltage can be efficiently detected.

[0025] The detection circuit comprises a voltage source and a current source connected in series with the detection resistor and configured to impress the current into the power path, or the detection circuit comprises a voltage source and an auxiliary resistor connected in series with the detection resistor and configured to impress the current into the power path.

[0026] This offers the technical advantage that a predetermined current can be impressed into the power path, or alternatively, it offers the technical advantage that the aforementioned current source is no longer needed and the auxiliary resistor can be used instead to impress a predetermined current into the power path. The detection circuit is thus simpler in design.

[0027] According to an exemplary embodiment of the semiconductor fuse, the detection circuit is configured to detect a voltage at a first terminal or a second terminal of the detection resistor and to determine, based on the detected voltage, whether the power path is high-impedance.

[0028] This offers the technical advantage that the resistance of the power path can be determined easily and accurately via such a voltage at one of the terminals of the detection resistor.

[0029] According to an exemplary embodiment of the semiconductor fuse, the detection circuit includes a comparator configured to compare the voltage at the first terminal or the second terminal of the detection resistor with a reference voltage.

[0030] This offers the technical advantage that the comparator provides a simple way to perform a threshold comparison. Depending on the result, a drift in the gate threshold voltage can be detected.

[0031] According to an exemplary embodiment of the semiconductor fuse, the comparator is configured to set a flag based on a result of the comparison, indicating whether or not there is a drift in the gate threshold voltage.

[0032] This offers the technical advantage that the comparator has a low latency and the result is available very quickly at its output, so that it can be quickly detected whether or not there is a drift in the gate threshold voltage.

[0033] According to an exemplary embodiment of the semiconductor fuse, the detection circuit is configured to indicate the presence of a drift in the gate threshold voltage when the voltage at the first terminal or the second terminal of the detection resistor is smaller than the reference voltage.

[0034] This offers the technical advantage that the detection circuit can indicate the presence of a drift in the gate threshold voltage of the controller, for example via the flag at the comparator output. The controller can either query the flag or receive it via a control input and thus react quickly to the presence of a drift in the gate threshold voltage and switch off the semiconductor switching element or diagnose a malfunction of the semiconductor switching element.

[0035] According to an exemplary embodiment of the semiconductor fuse, the detection circuit comprises a diode that is connected between the detection resistor and the at least one semiconductor switching element.

[0036] The diode serves to block the high-voltage voltage when the semiconductor switching element is in the blocking state. It is absolutely necessary in high-voltage applications, but not for low-voltage applications. Brief character description

[0037] The invention will now be described in more detail with reference to exemplary embodiments and the figures. The figures show: Fig. 1 a system circuit diagram of a charging system 100 for charging a battery of a battery-electric vehicle; Fig. 2 a simplified block diagram of a semiconductor fuse 200 according to the invention for a battery-electric vehicle; Fig. 3 a circuit diagram of a semiconductor fuse 200 according to the invention in one embodiment; Fig. 4 a diagram 400 with exemplary relevant voltage waveforms of the detection circuit at two different gate voltages; and Fig. 5 a circuit diagram of a semiconductor fuse 200 according to a further embodiment according to the invention.

[0038] The figures are merely schematic representations and serve only to illustrate the invention. Identical or equivalent elements are consistently identified by the same reference numerals.

[0039] The following detailed description refers to the accompanying drawings, which form part thereof and illustrate specific embodiments in which the invention can be implemented. It is understood that other embodiments can also be used and structural or logical modifications can be made without deviating from the concept of the present invention. Therefore, the following detailed description is not to be understood as limiting. Furthermore, it is understood that the features of the various embodiments described herein can be combined with one another, unless specifically stated otherwise.

[0040] The aspects and embodiments are described with reference to the drawings, where the same reference numerals generally refer to the same elements. For illustrative purposes, numerous specific details are presented in the following description to provide a thorough understanding of one or more aspects of the invention. However, it may be obvious to a person skilled in the art that one or more aspects or embodiments can be implemented with a lesser degree of specific detail. In other cases, known structures and elements are shown schematically to facilitate the description of one or more aspects or embodiments. It is understood that other embodiments may be used and structural or logical modifications may be made without departing from the concept of the present invention.

[0041] Fig. Figure 1 shows a system circuit diagram of a charging system 100 for charging a battery of a battery-electric vehicle.

[0042] The charging system 100 comprises 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 120 for charging the vehicle's battery 140, to which a capacitor C1 is connected in parallel and an inductor L1 is connected in series.

[0043] On the vehicle side, the electrical and electronic components of the vehicle include a battery 140 for powering the vehicle or an HV storage unit, which is connected in series with an inductor L3 at a first pole and an inductor L4 at a second pole of the battery in the charging current path 130.

[0044] An SBox 110 is connected to charging path 130 in the vehicle, which enables charging of battery 140. The SBox 110 is also connected to a traction path and one or more auxiliary consumer paths. The SBox 110 controls the charging of battery 140 and the operation of the traction path and auxiliary consumer paths via battery 140. Switches for connecting to the charging infrastructure are not shown.

[0045] The traction path includes an electric motor 150, to which a capacitor C2 is connected in parallel and an inductor L2 is connected in series.

[0046] The auxiliary consumer paths include one or more parallel-connected electronic components, such as PTC 151 and KMV 152, to which a capacitor C3 is connected in parallel and an inductor L5 is connected in series.

[0047] The SBox 110 comprises a charging infrastructure-side fuse F1 200, which can be a semiconductor fuse 200 according to the invention, as presented in this disclosure. The SBox 110 further comprises a battery-side fuse F3, an inductor L SBox and a circuit with switches connected in parallel S 31 and S 32 , which are connected in series with fuse F1 in the charging current path 130. The battery-side fuse F3 can also be implemented as a semiconductor fuse according to the invention. A second circuit with switches S4 and S2 branches off between fuse F1 and the inductor L. SBoxto connect the traction path and the auxiliary consumer paths to battery 140 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 implemented as a semiconductor fuse 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 battery 140 and auxiliary consumers 151, 152.

[0048] The SBox 110 also includes a capacity of C SBox , which is connected in parallel to the charging infrastructure.

[0049] Fig. Figure 2 shows a simplified block diagram of a semiconductor fuse 200 according to the invention for a battery-electric vehicle.

[0050] The semiconductor fuse 200 serves to safely disconnect an electrical load 112 from a power supply source 111 for a battery-electric vehicle. This can, for example, be the disconnection of the battery 140 from the charging station 120, as in Fig. 1 shown, or it may be a separation of the engine 150 or the auxiliary units 151, 152 from the battery 140, as in Fig. 1 shown.

[0051] The semiconductor fuse 200 comprises at least one semiconductor switching element 211, which can be switched between the power supply source 111 and the electrical load 112. Fig. Figure 2 shows only one such semiconductor switching element 211, but it can be a plurality of semiconductor switching elements that are connected in parallel to each other, for example, to increase the current-carrying capacity of the entire circuit, or a parallel connection of pairs of semiconductor switching elements in which the switching elements of the respective pairs are connected in opposite series to effect bidirectional blocking.

[0052] The at least one semiconductor switching element 211 has a gate control terminal 212 for controlling the switching on and off of the semiconductor switching element 211 in order to connect the electrical load 112 to the power supply source 111 or to disconnect it from the power supply source 111. The semiconductor switching element 211 can, for example, be a MOSFET or an IGBT, where the gate control terminal 212 corresponds to the gate terminal.

[0053] The semiconductor fuse 200 comprises a driver circuit 221 configured to apply a driver voltage 223 to the gate control terminal 212 of the at least one semiconductor switching element 211, which is smaller or larger than a predetermined gate threshold voltage 501 (see Fig. 5) of at least one semiconductor switching element 211.

[0054] For reliable disconnection, a drop in the threshold voltage is critical, as is the case to be detected. For other applications, a positive drift of the gate threshold voltage can also be critical. In such cases, it may be necessary to apply a drive voltage 223 to detect such a positive drift, for example, a drive voltage that is greater than the gate threshold voltage.

[0055] The specified gate threshold voltage is also referred to as the nominal gate threshold voltage and can be read from the datasheets of the semiconductor switching elements.

[0056] In particular, a driver voltage 223 can be applied here that lies outside a predefined threshold range around the specified gate threshold voltage, so that natural fluctuations in the gate threshold voltage do not lead to unintended drift detection. An example of such a predefined threshold range is the range of -1V / +1V around the specified gate threshold voltage.

[0057] The specified threshold range can be symmetrical around the specified gate threshold voltage, but it can also be non-symmetrical, e.g. defining a range of -1V / +0.5V to weight a positive deviation of the drift less than a negative deviation or vice versa.

[0058] The semiconductor fuse 200 comprises a detection circuit 222, which is configured to determine a resistance of the power path 130 of the at least one semiconductor switching element 211 and to detect a drift of the gate threshold voltage based on the resistance of the power path 130.

[0059] The semiconductor fuse 200 includes a control unit 220 which is designed to indicate a malfunction of at least one semiconductor switching element 211 when a drift of the gate threshold voltage is detected.

[0060] The at least one semiconductor switching element 211 can have a drain terminal and a source terminal, between which the power path 130 of the at least one semiconductor switching element 211 is formed. The resistance of the power path 130 can thus correspond to a resistance between the drain terminal and the source terminal. The at least one semiconductor switching element 211 can be a field-effect transistor, for example a MOSFET. The at least one semiconductor switching element 211 can be an IGBT.

[0061] The gate control terminal 212 of the at least one semiconductor switching element 211 can have a gate resistor R8, as shown in the Fig. 3 and Fig. Figure 5 shows the following. The driver circuit 221 can be configured to apply the driver voltage 223 to the gate resistor R8 of the gate control terminal 212. The detection circuit 222 can be configured to determine the resistance of the power path 130 as a function of a gate voltage at the gate control terminal (212).

[0062] The detection circuit 222 is connected in parallel to at least one semiconductor switching element 211, as shown in the Fig. 3 and Fig. 5 shown, and be designed to impress a current into the power path 130 of the at least one semiconductor switching element 211.

[0063] The detection circuit 222 includes a detection resistor R2, as shown in the Fig. 3 and Fig. 5 shown, and designed to guide the current impressed into the power path 130 of the at least one semiconductor switching element 211 via the detection resistor R2.

[0064] The detection circuit 222 can include a voltage source V2 and a current source I1, as shown in Fig. 3 shown, which are connected in series to the detection resistor R2 and are designed to impress the current into the power path 130.

[0065] Alternatively, the detection circuit 222 can include a voltage source V2 and an auxiliary resistor R1, as shown in the figure, which are connected in series with the detection resistor R2 and are configured to impress the current into the power path 130.

[0066] The detection circuit 222 can be configured to apply a voltage to a first terminal TP1 or a second terminal TP2 of the detection resistor R2, as shown in the Fig. 3 and Fig. 5 shown, to detect and, based on the detected voltage, to determine whether the power path 130 is high impedance.

[0067] The detection circuit 222 can include a comparator 229, as shown in the Fig. 3 and Fig. 5 shown, which is designed to compare the voltage at the first terminal TP1 or the second terminal TP2 of the detection resistor R2 with a reference voltage V3.

[0068] The comparator 229 can be configured to set a flag 228 based on the result of the comparison, as shown in the Fig. 3 and Fig. Figure 5 shows whether or not there is a drift in the gate threshold voltage.

[0069] The detection circuit 222 can be configured to indicate the presence of a drift of the gate threshold voltage when the voltage at the first terminal TP1 or the second terminal TP2 of the detection resistor R2 is smaller than the reference voltage V3.

[0070] Fig. Figure 3 shows a circuit diagram of a semiconductor fuse 200 according to one embodiment of the invention.

[0071] The semiconductor fuse 200 in Fig. 3 corresponds to the one in Fig. 2 shown semiconductor fuse 200, wherein in Fig. Figure 3 shows details of the interconnection of the driver circuit 221 and the detection circuit 222 with the semiconductor switching element 211. The semiconductor switching element 211 can be a MOSFET (M1), as shown in Fig. 3 shown as examples.

[0072] The semiconductor switching element 211 has a gate control terminal 212 for controlling the switching on and off of the semiconductor switching element 211. The gate control terminal 212 corresponds to the gate terminal of the MOSFET M1, as shown in the Fig. 3 shown.

[0073] The driver circuit 221 is configured to apply a driver voltage (U_G driver) 223 to the gate control terminal 212 of the MOSFET M1, which is lower than a predetermined gate threshold voltage of the MOSFET M1. The driver circuit 221 can, for example, be a voltage source V1.

[0074] The detection circuit 222 is designed to determine a resistance of the power path 130 of the MOSFET M1, 211 and to detect a drift of the gate threshold voltage based on the resistance of the power path 130.

[0075] The semiconductor fuse 200 includes a control unit 220, which is located in Fig. Figure 3 is not shown. The controller 220 is designed to indicate a malfunction of MOSFET M1 when a drift in the gate threshold voltage is detected.

[0076] The MOSFET M1 has a drain terminal and a source terminal, between which the power path 130 of the MOSFET M1 is formed. The resistance of the power path 130 can therefore correspond to a resistance between the drain terminal and the source terminal, i.e., an R DS .

[0077] The gate control terminal 212 of the MOSFET M1 has a gate resistor R8. The driver circuit 221 is configured to apply the driver voltage 223 to the gate resistor R8 of the gate control terminal 212. The detection circuit 222 is configured to determine the resistance of the power path 130 as a function of a gate voltage at the gate control terminal 212.

[0078] The detection circuit 222 is connected in parallel to the MOSFET M1, as shown in Fig. 3 evident, and designed to impress a current into the power path 130 of the MOSFET M1.

[0079] The detection circuit 222 has a detection resistor R2 and is designed to guide the current impressed into the power path 130 of the MOSFET M1 through the detection resistor R2.

[0080] The detection circuit 222 comprises a voltage source V2 and a current source I1, which are connected in series with the detection resistor R2 and are designed to impress the current into the power path 130.

[0081] The detection circuit 222 is configured to apply a voltage to a first terminal TP1 or a second terminal TP2 of the detection resistor R2, as shown in Fig. 3 shown, to detect and, based on the detected voltage, to determine whether the power path 130 is high impedance.

[0082] The detection circuit 222 comprises a comparator (U1) 229, which is configured to compare the voltage at the first terminal TP1 or the second terminal TP2 of the detection resistor R2 with a reference voltage V3. Fig. Figure 3 shows that the comparator 229 compares the voltage at the second terminal TP2 of the detection resistor R2 with the reference voltage V3. The reference voltage V3 can be provided, for example, by a reference voltage source V_REF.

[0083] The comparator 229 is configured to set a flag (V_TH_DRIFT_FLAG) 228 at its output based on a result of the comparison, indicating whether or not there is a drift of the gate threshold voltage.

[0084] The detection circuit 222 is configured to indicate the presence of a drift in the gate threshold voltage when the voltage at the first terminal TP1 or the second terminal TP2 of the detection resistor R2 is lower than the reference voltage V3, here in Fig. 3 is the second connection TP2.

[0085] The detection circuit 222 further includes a diode D1, which is connected between the detection resistor R2 and the at least one semiconductor switching element M1. The diode D1 is reverse-biased across the HV input (HV_PLUS) and serves to block the HV voltage when the semiconductor switching element M1 is in the blocking state. This is essential in the high-voltage range, but not for applications in the LV (low-voltage) range.

[0086] The functionality of the semiconductor fuse 200 is explained in more detail below.

[0087] Before the main fuse or, depending on the installation location, the second main fuse closes the entire system (see Fig. 1) releases, a voltage is applied to the control terminal 212 (gate in the case of a MOSFET) of the dFUSE 200 using a driver circuit (V1, 221) which is smaller than the typical gate threshold voltage (U_G_MOSFET, 226).

[0088] A detection circuit 222, also known as the "DESAT circuit," is then used to check whether the power path 130 (M1, drain-source) has a high resistance and whether the power semiconductor is still in the blocking state. This corresponds to the "OK" case.

[0089] A current is impressed using V2 and I1.

[0090] D1 is used to block the HV voltage when the semiconductor switch M1 is in the blocking state.

[0091] If the semiconductor M1 has a high resistance, the voltage at TP1 will be that of V2.

[0092] This can be evaluated using a comparator circuit (U1) 229 (setting an error flag 0 corresponds to "not OK"; 1 corresponds to "OK"). If U_TP1 > V3, then the gate voltage measurement is OK.

[0093] In Fig. Figure 4 shows the relevant voltage curves of the detection circuit 222.

[0094] If the gate threshold voltage has drifted downwards due to a fault or aging, the semiconductor M1 is no longer blocking and the voltage at TP1 is smaller than that of the reference voltage source V3.

[0095] Using a resistor R2 and a measuring tap TP2, the magnitude of the drain-source resistance can be determined at the applied test voltage or the driver voltage 223. The drain-source resistance is either less than or greater than R2.

[0096] If the gate threshold voltage drift detection was successful, the “normal” gate voltage (for example 12V / 15V for Si_MOSFETs or 18V / 21V for SIC-MOSFETs) can be applied and the entire system can be enabled by the second main contactor.

[0097] The diagnostic method described here also works with multiple semiconductors connected in parallel.

[0098] Key features of the solution described here for gate threshold voltage measurement are the determination of the drain-source resistance and the application of a gate voltage smaller than the gate threshold voltage.

[0099] Another implementation is in Fig. Figure 5 shows that the current source I1 is not required. In the implementation without a current source according to... Fig. 5. A resistor is absolutely necessary (R2); a second (R1) or more are optional.

[0100] Filter circuits (e.g., RC low-pass filters) and parasitic line inductances are not shown for better readability.

[0101] Fig. Figure 4 shows a diagram 400 with exemplary relevant voltage waveforms of the detection circuit at two different gate voltages, using the gate voltages 3V and 6V as examples.

[0102] The top diagram shows the voltage profile over time at measuring point TP1 (see Fig. 3) Curve 401 shows the "OK" case, in which there is no voltage drop; curve 402 shows the "Not OK" case, in which there is a voltage drop.

[0103] The second diagram from the top shows the voltage profile over time at measuring point TP2 (see Fig. 3) Curve 403 shows the "OK" case, in which there is no voltage drop; curve 404 shows the "Not OK" case, in which there is a voltage drop.

[0104] The third diagram from the top shows the voltage waveform over time at the output (V_TH_DRIFT_FLAG) 228 of the comparator (U1) 229 (see Fig. 3) Curve 405 shows the "OK" case, where the flag remains at 1; curve 406 shows the "Not OK" case, where the flag switches to 0 over time.

[0105] The fourth diagram from the top shows the voltage waveform over time at the gate control input or gate (U_G-MOSFET) of MOSFET M1 (see Fig. 3) Curve 408 shows the “OK” case, in which the voltage remains constant after an initial rising edge; curve 407 shows the “Not OK” case, in which the voltage exhibits a further rising edge over time after the initial rising edge.

[0106] The waveforms with the gate voltage 3V show the "OK" case, while the waveforms with the gate voltage 6V show the "Not OK" case, in which the MOSFET M1 is switched on.

[0107] If the gate threshold voltage has drifted downwards due to a fault or aging, the semiconductor M1 is no longer blocking and the voltage at TP1 is smaller than that of the reference voltage source V3.

[0108] Fig. Figure 5 shows a circuit diagram of a semiconductor fuse 200 according to a further embodiment of the invention.

[0109] The semiconductor fuse 200 in Fig. 5 corresponds to the one in Fig. 3 semiconductor fuse 200 shown, where the current source I1 is from Fig. 3 in Fig. 5 is replaced by resistor R1.

[0110] Alternatively to the one in Fig. The detection circuit 222 described in section 3 can be used to detect the detection circuit 222 of the Fig. 5 comprising the voltage source V2 and the auxiliary resistor R1, which are connected in series with the detection resistor R2, and are designed to impress the current into the power path 130.

[0111] With the semiconductor fuse 200 according to Fig. 5. Similar voltage patterns emerge as in Fig. 4 shown. REFERENCE MARK LIST 100 charging system 110 SBox 120 charging stations 140 battery or HV storage 150 electric motor or traction 151 Auxiliary consumers, PTC resistor 152 secondary consumers KMV 111 Energy supply source 112 electrical consumers, load 130 Charging current path or switching path of the semiconductor switching element 200 semiconductor fuse, dFuse, semiconductor-based fuse 211 semiconductor switching element(s), M1 221 Driver circuit, V1 222 Detection circuit 220 control 212 Gate control connection or control terminal of the semiconductor switching element 223 Driver voltage, U_G driver 226 Gate voltage at the gate control terminal, U_G-MOSFET R8 Gate resistor 229 Comparator, U1 228 Output of comparator 229, V_TH_DRIFT_FLAG R2 detection resistor V2 voltage source I1 Power source D1 Diode TP1 first measuring point at the first connection of the detection resistor R2 TP2 second measuring point at the first connection of the detection resistor R2 V_REF Reference voltage source R1 resistor as an alternative to the current source I1 401, 402 Time course of voltages at measuring point T2 403, 404 Time course of voltages at measuring point T1 405, 406 Time course of voltages at the comparator output 407, 408 Time course of the gate voltage at MOSFET M1

Claims

[1] Semiconductor fuse (200) for safely disconnecting an electrical load (112) from a power supply source (111) for a battery-electric vehicle, wherein the semiconductor fuse (200) comprises: at least one semiconductor switching element (211) that can be switched between the power supply source (111) and the electrical load (112), wherein the at least one semiconductor switching element (211) has a gate control terminal (212) for switching on and off a power path (130) of the at least one semiconductor switching element (211) in order to switch the electrical load (112) to the power supply source (111) or to disconnect it from the power supply source (111); a driver circuit (221) configured to apply a driver voltage (223) to the gate control terminal (212) of the at least one semiconductor switching element (211), which is smaller or larger than a predetermined gate threshold voltage of the at least one semiconductor switching element (211); a detection circuit (222) configured to determine the resistance of the power path (130) of the at least one semiconductor switching element (211) and to detect a drift of the gate threshold voltage based on the resistance of the power path (130); and a control (220) configured to indicate a malfunction of the at least one semiconductor switching element (211) upon detection of a drift of the gate threshold voltage, wherein the detection circuit (222) is connected in parallel to the at least one semiconductor switching element (211) and is configured to induce a current in the power path (130) of the at least one semiconductor switching element (211), wherein the detection circuit (222) includes a detection resistor (R2) and is configured to guide the current impressed into the power path (130) of the at least one semiconductor switching element (211) through the detection resistor (R2), wherein the detection circuit (222) comprises a voltage source (V2) and a current source (I1) connected in series with the detection resistor (R2) and configured to impress the current into the power path (130); or wherein the detection circuit (222) comprises a voltage source (V2) and an auxiliary resistor (R1) connected in series with the detection resistor (R2) and configured to impress the current into the power path (130). [2] Semiconductor fuse (200) according to claim 1, wherein the driver circuit (221) is configured to apply a driver voltage (223) to the gate control terminal (212) of the at least one semiconductor switching element (211), which lies outside a predetermined threshold range around the predetermined gate threshold voltage. [3] Semiconductor fuse (200) according to claim 1 or 2, wherein the at least one semiconductor switching element (211) has a drain terminal and a source terminal, between which the power path (130) of the at least one semiconductor switching element (211) is formed, wherein the resistance of the power path (130) corresponds to a resistance between the drain terminal and the source terminal. [4] Semiconductor fuse (200) according to one of the preceding claims, wherein the gate control terminal (212) of the at least one semiconductor switching element (211) has a gate resistor (R8); wherein the driver circuit (221) is configured to apply the driver voltage (223) to the gate resistor (R8) of the gate control terminal (212); and wherein the detection circuit (222) is configured to determine the resistance of the power path (130) as a function of a gate voltage at the gate control terminal (212). [5] Semiconductor fuse (200) according to one of the preceding claims, wherein the detection circuit (222) is configured to detect a voltage at a first terminal (TP1) or a second terminal (TP2) of the detection resistor (R2) and to determine, based on the detected voltage, whether the power path (130) is high impedance. [6] Semiconductor fuse (200) according to claim 5, wherein the detection circuit (222) comprises a comparator (229) configured to compare the voltage at the first terminal (TP1) or the second terminal (TP2) of the detection resistor (R2) with a reference voltage (V3). [7] Semiconductor fuse (200) according to claim 6, wherein the comparator (229) is configured to set a flag (228) based on a result of the comparison, indicating whether or not there is a drift of the gate threshold voltage. [8] Semiconductor fuse (200) according to claim 6 or 7, wherein the detection circuit (222) is configured to indicate the presence of a drift of the gate threshold voltage when the voltage at the first terminal (TP1) or the second terminal (TP2) of the detection resistor (R2) is less than the reference voltage (V3). [9] Semiconductor fuse (200) according to one of the preceding claims, wherein the detection circuit (222) comprises a diode (D1) connected between the detection resistor (R2) and the at least one semiconductor switching element (211).

Images