Apparatus and method for monitoring switchability

Abstract

The invention relates to a device and a method for monitoring turn-off performance. The invention relates to a device for monitoring the switching-off of an electrical consumer connected to a first current path in which a first electrical control element is arranged, the current passage capacity of which can be varied by a first control signal and is characterized by a first electrical variable (capacitance or voltage determined by a voltage measuring device). In addition, the device is provided with a second control element in the second current path for providing a first control signal, the current passage capacity of which can be varied by a second control signal and which is characterized by a second electrical variable (capacitance or voltage). The two capacitance capacities are connected in series, the control device actuates the second control element by means of a second control signal and evaluates a value of the first electrical variable in order to detect a malfunction of the first control element, said evaluation comprising a comparison of said value with at least one reference predetermined value.

Description

Technical Field

[0001] The disclosure relates to a device for monitoring the switchability of a consumer, in particular by means of a switching element. The disclosure also relates to a method for monitoring the switchability, as well as a control device, a system and a computer program. Background Art

[0002] A typical challenge for such devices can be to be able to diagnose whether a digital output can be switched off in the switched-on state. This is especially true when a load is coupled.

[0003] In the field of functional safety, for example in accordance with the SIL standard IEC 61508 and with performance levels according to IEC 13849, safety functions should provide a very high probability according to their specifications in order to prevent third-party injuries, irreversible damage and accidents resulting in death. It should be possible to ensure that safe digital outputs can be switched off with a high probability.

[0004] Measures and methods for diagnosing the switch-off capability are known from the prior art. For example, it can be provided that the switch-off is performed periodically in a time range of 1 ms to every 500 ms. In practical applications, such periodic switch-offs can be destructive to the function of the switching element. Therefore, it may be necessary to diagnose the switch-off capability and ensure a high probability that no switch-off is required.

[0005] Several methods have been proposed in the prior art. DE 10 2020 113 822 A1 shows a safe output in which the output switching elements do not need to be periodically switched off for testing, because they are located in a control loop, through which their functionality can be monitored. The main disadvantage of this solution is that the output switching elements cannot be fully controlled to conduct when they are in the control loop and the voltage drop across the semiconductor section is higher than the voltage drop in the fully controlled on state. This results in unnecessary heating of the switching elements. In addition, the control loop is complex in design and requires a large number of components, which in turn leads to larger and more expensive circuit boards.

[0006] US 007 702 302 B1 shows an interconnection circuit having a FET and a measuring resistor for current measurement in a power supply. A disadvantage of US 007 702 302 B1 is that a periodic test of the FET in the on state is not possible, so that a high level of safety cannot be achieved. In addition, the measuring resistor is connected in the power path, which may cause power losses.

[0007] US2012 / 0161817 A1 describes a circuit for supplying electrical power to the coil of a relay. The current required for this purpose can be provided by a battery. Two feeder lines extending parallel to each other are provided, in which field effect transistors are respectively provided as switches. In order to energize the coil, the gate voltage of the field effect transistor is synchronously adjusted to a value that causes current to flow through the two field effect transistors. The gate voltage is slightly reduced at regular time intervals and the voltage drop between the drain and the source is measured. The measured values ​​are evaluated with respect to wire interruptions in the feeder line to the field effect transistor. Disadvantageously, the blocking layer capacitance is not measured. Instead, the FET is only periodically actuated at a lower voltage. In addition, the load voltage must also be measured. A measuring system with a higher fail-safety is not disclosed here.

[0008] EP 133 5471 A2 and DE 382 1065 show a protective circuit implemented by a "monitor" transistor. If the voltage across the main transistor drops too high, the main transistor is switched off. The disadvantage is that the main transistor is only protected if the voltage across the main transistor drops too high, but not if the main transistor becomes low-ohmic due to a fault and can no longer be switched off.

[0009] In the case described, it is not possible to diagnose the switchability of a digital output in the switched-on state. Against the background of this prior art, the object of the disclosure is to specify a device and a method which are each suitable for at least partially overcoming the above-mentioned disadvantages of the prior art and for improving the prior art. Summary of the invention

[0010] This object is achieved by the features of the independent patent claims. The parallel patent claims and the dependent claims each have optional developments of the present disclosure.

[0011] Thus, the object is achieved by a device for monitoring the switchability of an electrical consumer connected to a first current path having a current supply mechanism. An electrical first regulating element is provided in the first current path, the current passing capacity of which can be changed by means of a first regulating signal. The operating state of the first regulating element is characterized by a first electrical parameter, which is a first capacitance on the first regulating element and, as the case may be, a first voltage known by a voltage measuring device. The device is provided with a second regulating element for providing a first regulating signal in a second current path having another current supply mechanism, the current passing capacity of which can be changed by means of a second regulating signal. The operating state of the second regulating element is characterized by a second electrical parameter, which is a second capacitance on the second regulating element and, as the case may be, a second voltage. The first capacitance and the second capacitance are connected in series. In addition, a control device is provided, which is designed to control the second regulating element by means of a second regulating signal at least at measuring intervals spaced apart in time from one another, and to evaluate the value obtained here for the relevant first electrical variable in order to identify a fault related to the shutdown situation of the first regulating element, and wherein the evaluation includes comparing the obtained value for the relevant first electrical variable with at least one reference predetermined value.

[0012] In the sense of the present disclosure, the capacitance It can be understood as an electrical parameter that has the ability to store charge and build up capacitance. Capacitance can be built up by applying voltage.

[0013] In the sense of the present disclosure, switchability can be understood as a capability of a regulating element, such as a field effect transistor (FET), in which the current flow between the source and the drain can be completely interrupted when an appropriate control voltage is applied to the gate. Switchability occurs when the voltage on the gate is adjusted so that the electric field in the channel is strong enough to completely block the current flow. In this state, the FET is considered to be "off", and only a very small leakage current flows between the source and the drain. The ratio between the leakage current in the off state and the maximum current in the on state can be called the off ratio or the off current ratio.

[0014] In the sense of the present disclosure, an electrical consumer may denote a device or component in an electrical system that absorbs electrical energy and converts or utilizes it into another form of energy.

[0015] In the sense of the present disclosure, the current passing capability of a field effect transistor refers to the ability of the transistor to conduct current between the source terminal and the drain terminal when an appropriate control voltage is applied on the gate.

[0016] The above-described device provides a series of advantages. In addition, the disclosed device can detect that the voltage of the barrier capacitor is below a predefined threshold value, so that the regulating element (field effect transistor) can no longer be turned off and it can no longer be ensured that the digital output and / or the electrical load are switched to a voltage-free state. Further protective measures can therefore be taken. It can be provided that the second disconnection mechanism is activated and the digital output and / or the electrical load are switched to a voltage-free state. In addition, in the case of a switching element, it can be detected that the disconnection is no longer ensured and a fault message can be output in order to avoid / prevent a reconnection.

[0017] Possible improvements to the above method will be explained in detail below.

[0018] It can be proposed that a capacitor is provided in the device. The capacitor can be coupled in parallel with the second regulating element to increase the capacitance of the second regulating element. The capacitance (especially the barrier layer capacitance) can be measured / known by a capacitive voltage divider. For this purpose, another capacitor is connected in series with the capacitance to be measured (GS section capacitance) of the first regulating element. The second regulating element can switch on the capacitance. In the switching state of the second regulating element, the capacitance is bridged. In the non-switching state (cut-off state), the capacitance is switched and the voltage drops. Alternatively, it can be proposed that the second regulating element has a drain-source capacitance, and its specifications are determined in the following manner so that it meets the task of the capacitance. If the specifications of the drain-source capacitance are determined to be too small, and / or the second regulating element requires a larger structural type to achieve the corresponding capacitance, then another capacitor can be connected in parallel with the second regulating element, and the other capacitor can have a correspondingly larger capacitance.

[0019] It can be provided that the second capacitance or the second capacitance connected in parallel with the capacitance has the same capacitance level as the first capacitance characteristic, and wherein the capacitance level is in the range of at least 100 pF to at most 10 nF. Thus, a corresponding voltage divider and a corresponding voltage drop can be implemented so that the first regulating element can still be switched, but at the same time the gate-source voltage is known.

[0020] It can be provided that the first regulating element and the second regulating element are transistors and that the regulating signal is a control current or a control voltage, wherein it can be provided that the transistors are n-channel or p-channel field effect transistors.

[0021] It can be provided that the voltage measuring device is designed as an operational amplifier. By means of the operational amplifier, the value determined for the gate-source voltage can be compared with a reference value. The difference can be evaluated accordingly and the result can be traced back to the switch-off characteristic or a fault occurring in the switch-off characteristic. Furthermore, the difference can be transmitted to a control device and processed by the control device.

[0022] It can be provided that the voltage measuring device is designed as an analog-to-digital converter and provides a digital signal to the control device as a function of the value of the first electrical variable. The value of the first electrical variable obtained as an analog voltage signal can be converted into a digital signal by means of the analog-to-digital converter. The converted digital signal can be transmitted to the control device for further processing.

[0023] It can be provided that the control device compares the value of the first electrical variable with at least one first reference predetermined value and / or a second reference predetermined value, and wherein the reference predetermined value / values ​​are provided by means of a resistive voltage divider. The reference predetermined values ​​can be adjusted by means of resistors so that they represent the limits of the voltage values ​​at which the first adjusting element can still be technically switched off. If the first adjusting element can no longer be switched off, for example due to complete melting, the value obtained for the first electrical variable will be outside the value range provided by the resistive voltage divider.

[0024] It can be provided that, in order to detect the absence of a fault with respect to the switching-off of the first regulating element, the first electrical variable is reduced from a maximum value by a factor such that the first regulating element is still not switched off or, if already switched off, remains switched off and a sufficient current flows through the consumer to carry out the consumer function. It can be detected that the barrier capacitance is normally present when the applied voltage is reduced to a level sufficient to switch on the first regulating element. The first regulating element is therefore still determined to be switchable. After sending the measuring pulse, the method for monitoring the switchability is terminated and the initial state of the device is entered again and the circuit operates in normal mode (e.g. for switching on electrical consumers).

[0025] It can be proposed that a third regulating element is provided in the first current path and is connected in series with the first switching element. If the barrier capacitance drops due to complete melting and the voltage thus dropped is also below the reference predetermined value, it is determined that the first regulating element can no longer be turned off and the corresponding task in the device is no longer completed in accordance with the standard, so that the digital output or the electrical load can be turned off by an alternative turn-off route. The alternative turn-off route is provided by the third regulating element. In addition, a fault report can also be provided by the control device through a signal light, a display on a display screen, or a message transmitted to another device to warn the operator / user.

[0026] It can be provided that, in order to detect a fault in relation to the switch-off of the first control element, the first electrical variable is reduced by as much as possible from a maximum value without the first control element being switched off, and a current sufficient to carry out the consumer function is prevented by means of the third control element. The device can thus be switched to a safe state and the digital outputs or electrical loads can be switched to a voltage-free state, thereby preventing damage to third parties.

[0027] It can be proposed that the device also has a resistance element, and wherein the resistance element is connected in parallel with the first capacitance of the first regulating element. The device is designed so that when the second regulating signal is not applied to the second regulating element, the digital output is turned off. Therefore, the switching conduction energy is only provided for the duration of the short test pulse. For this purpose, a resistance element can be provided, the size of which can be determined as follows, so that any fault on the second regulating element will not cause the first regulating element to not be turned off within a predetermined process safety time.

[0028] The above content can be summarized in other words and in combination with possible more specific design solutions of the present disclosure described below, wherein the following description should not be interpreted as limiting the present disclosure.

[0029] The switchability of the digital outputs should be diagnosed in the switched-on state by measuring the barrier capacitance of the switching field effect transistor.

[0030] Field effect transistors can be constructed in such a way that the substrate is doped and thus an N region and a P region are obtained. For example, the N region of a self-cutoff N-channel field effect transistor (FET) can be in contact with D (drain) and S (source). The field effect transistor can have an insulating layer in the P region so that the G (gate) terminal is not conductively connected. The barrier layer is located in this region. When a voltage is applied to S on G, a capacitive charge is generated, through which the barrier layer between D and S is made conductive.

[0031] As a result of this structure, the FET has a barrier capacitance that can be measured between G and S. This capacitance can be measured even in the on-state when the barrier is charged with voltage.

[0032] The FET can have two main failure states between D and S: On the one hand, it can become permanently high-ohmic. Then, it cannot be controlled to turn on by applying a voltage on G towards S. If the off state is a safe state, the FET fails in the safe direction. On the other hand, the FET can also become permanently low-ohmic. Here, the cut-off region is "completely melted". At this point, the FET can no longer be turned off. In the completely melted state, the FET no longer has the same barrier capacitance. Since the conductive part of the cut-off region has the potential of the S pole of the barrier capacitance, the barrier capacitance is reduced. Therefore, the capacitance between G and S is significantly reduced. The dielectric must have regions that are rich in charge carriers and therefore also regions that are depleted of charge carriers. Complete melting occurs in the most direct connection between the doped regions, that is to say equivalent to the enriched region. It is therefore considered that the remaining barrier capacitance is less than 50% of the previous barrier capacitance.

[0033] The capacitance can be measured by a capacitive voltage divider. To this end, an additional capacitor is connected in series with the capacitance to be measured. An additional FET can switch on this capacitance. The FET itself has a drain-source capacitance, which can be dimensioned so that it is sufficient for this purpose. Alternatively, an additional capacitor can also be switched on.

[0034] The barrier capacitor and the series capacitor can be dimensioned so that they are of the same order of magnitude, for example in the range between 100 pF and 10 nF. If the other FET is switched to high ohm, the charge of the barrier capacitor is shunted to the capacitive voltage divider. The divided voltage should be sized so that the barrier capacitor has enough charge to continue controlling the on-FET. The divided voltage can be queried in terms of the range it should be in.

[0035] If the FET has completely melted, the voltage is outside the valid range. It can therefore be diagnosed that the FET can no longer be switched off. To measure the voltage across the capacitive voltage divider, an operational amplifier can be provided which compares the voltage provided via the resistive voltage divider with a reference voltage.

[0036] Alternatively, the voltage can be detected using other measuring measures, for example using an analog-to-digital converter of a microcontroller.

[0037] The application also has in particular an additional shutdown path, for example an additional FET connected in series with the abovementioned FET. If it is found during the test that the FET can no longer be switched off, ie has completely melted, a shutdown is triggered via the redundant shutdown path.

[0038] The application also has a control mechanism, such as a gate driver or a digital output of a microcontroller at the D of the further FET. The diagnostic interconnection circuit is designed such that the output is switched off when no voltage is applied to the D of the further FET. The switching-on energy is therefore only available for the duration of the short test pulse.

[0039] For this purpose, a resistor can be provided, the size of which is determined so that any failure of the other FET does not lead to the FET not shutting down within the predetermined process safety time. The interconnection circuit is designed as follows so that any simple failure does not lead to the loss of the safety function and the existing diagnostic coverage is very high. During the test, the FET is temporarily not fully controlled to conduct. This leads to an increase in the voltage drop (DS section) and thus to heating. An advantageous design of the FET can be to over-determine the size so that it can withstand a power higher than the power required for the current measured when it is permanently fully controlled to conduct.

[0040] The switchability of the initial FET can be checked using the following method.

[0041] The initial state includes: voltage is applied to the D of another FET, voltage is applied to G, the other FET is switched on (DS section), voltage is applied to G of FET, voltage is supplied to D of FET, and FET is switched on (DS section).

[0042] Apply a test pulse to the G of the other FET, thereby making the GS voltage zero and making the other FET high ohmic. Measure the reverse capacitance of the capacitor and the other FET A capacitive voltage divider is formed with the charged barrier capacitance of the FET. Thus, the FET is discharged according to the capacitance ratio and the resulting voltage is retained on the G of the FET.

[0043] If the barrier capacitance is present normally, the voltage across the G of the FET can be measured. A reduced voltage is then applied, but the reduced voltage is still sufficient to switch the FET on. If the barrier capacitance is significantly reduced due to complete melting, the applied voltage is significantly reduced.

[0044] The assessment of whether the voltage is below a defined threshold can be made according to the following criteria: If the voltage is only slightly reduced, the FET can still be turned off.

[0045] The test pulse ends and the initial state is reached again.

[0046] If the voltage drops below a defined threshold, the FET can no longer be switched off. The output is switched off via a second switch-off path. A fault message is output and switching back on is prevented. If the gate voltage U_G of the FET is detected both with and without test pulses, the following faults can be detected:

[0047] (1) Complete melting of the FET (DS path is low-ohmic) leads to a reduction in the capacitance C_GS and thus to an increase in the voltage U_G during the test pulse.

[0048] (2) Complete melting of the FET (DG section or SG section is low ohmic) causes the gate to close, and thus causes the voltage to decrease (or increase). Complete melting or high ohmicity (DS section) of another FET causes the capacitive voltage divider to change, and thus causes the voltage to decrease or increase.

[0049] If a fault condition is detected, shutdown is performed.

[0050] Alternatively, in a second variant it can be provided that the drain-source voltage variation caused by the capacitive discharge is measured. This can be done 1. by means of an interconnection circuit that measures only the alternating voltage component or 2. by means of a bandpass filter if it is periodically switched off and on at a certain frequency. It is also possible to detect and measure the voltage with the aid of an analog-to-digital converter.

[0051] Furthermore, a method for monitoring the switchability of an electrical consumer connected to a first current path having a current supply is provided, wherein a first electrical regulating element is provided in the first current path, the current carrying capacity of the first regulating element being changeable by means of a first regulating signal, wherein the operating state of the first regulating element is characterized by a first electrical variable, which is a first capacitance at the first regulating element and, if appropriate, a first voltage detected by a voltage measuring device, wherein the device is provided with a second regulating element for providing the first regulating signal in a second current path having a further current supply, the second regulating element The current carrying capacity of the node element can be changed by means of a second control signal, wherein the operating state of the second control element is characterized by a second electrical variable, which is a second capacitance at the second control element and, if appropriate, a second voltage, wherein the first capacitance and the second capacitance are connected in series, and wherein the control device controls the second control element by means of the second control signal at least at measuring intervals spaced apart in time from one another and evaluates the value obtained in this regard for the first electrical variable in order to identify a fault related to the shutdown state of the first control element, and wherein the evaluation includes comparing the obtained value with a reference predetermined value.

[0052] In addition, a control device for controlling a device according to the present disclosure is provided, the control device being designed to implement a method according to the present disclosure, the control device comprising: a processor unit being designed to provide a control signal so as to control a second regulating element at least at measurement intervals spaced apart from each other in time; an interface being designed to provide a control signal and to receive a value of a first electrical parameter obtained for the first regulating element; and wherein the processor unit is also designed to provide a control signal so as to evaluate a fault in identifying a shutdown condition of the first regulating element, and wherein the evaluation comprises comparing the value of the first electrical parameter obtained with at least one reference predetermined value.

[0053] Furthermore, a system is provided having a first device and a second device according to the present disclosure, wherein the first device and the second device are therefore present in particular in a duplicated manner and are arranged such that the negative pole of the first (upper) device (100) is coupled to the positive pole of the (lower) device (100).

[0054] In addition, the present disclosure also relates to a computer program. The above-mentioned method design scheme can also be designed as a computer program, wherein, when the computer program is implemented on a control device or a processor of a control device, the control device (e.g., a computer, a microcontroller, a DSP, an FPGA and / or an SPS) is prompted to perform a method according to the present disclosure. The computer program can be provided as a signal by downloading, or stored in a memory unit of the control device containing a computer-readable program code, so as to prompt the control device to implement instructions according to the above-mentioned method. Here, the computer program can also be stored on a machine-readable storage medium.

[0055] Therefore, an alternative object solution proposes a storage medium, in particular a computer-readable storage medium, which is designed to store the method according to the present disclosure (as program code) and can be read by a computer or a processor of a computer. When implemented by a processor circuit of a computer or a computer network, the program code causes the implementation of the embodiment of the method according to the present disclosure.

[0056] For example, the storage medium can be provided at least partially as a non-volatile data memory, such as a flash memory and / or an SSD (solid state drive) and / or at least partially as a volatile data memory, such as a RAM (random access memory). The storage medium can be arranged in its data memory in the processor circuit. However, the storage medium can also be operated, for example, as a so-called application store server in the Internet. A processor circuit with at least one microprocessor can be provided by a computer or a computer network. The program code can be provided as a binary code or an assembly language and / or as a source code in a programming language, such as the C language, and / or as a program script, such as Python.

[0057] The above-mentioned designs and improvements can be combined with each other arbitrarily when it makes sense. Other possible designs, improvements and implementations of the present disclosure also include combinations of features described in the above or below improvements of the present disclosure that are not explicitly mentioned. In particular, those skilled in the art will also add each single viewpoint as an improvement or supplement to the corresponding basic form of the present disclosure. In particular, the features of the device claims can be realized and / or implemented by corresponding functions, based on which they can supplement or expand the method. In addition, the method steps can be implemented by corresponding implementation modules in the device. Therefore, the content described above for the device is also similarly applicable to the method, and vice versa accordingly. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Further details and advantages of the present disclosure will now be explained in more detail based on the embodiments shown in the drawings.

[0059] In the attached picture:

[0060] Figure 1 shows a schematic diagram of an apparatus according to the present disclosure;

[0061] Figure 2 A schematic diagram of a system according to the present disclosure is shown;

[0062] Figure 3 shows a further schematic diagram of an apparatus according to the present disclosure;

[0063] Figure 4 A flowchart showing a method according to the present disclosure is shown; and

[0064] Figure 5 A schematic diagram of a control device according to the present disclosure is shown. DETAILED DESCRIPTION

[0065] The accompanying drawings are intended to help further understand the improvements of the present disclosure. These drawings illustrate several improvements and are used in conjunction with the specification to illustrate the principles and concepts of the present disclosure. In view of these drawings, different improvements and many of the advantages mentioned therein are obtained. The elements of the drawings are not necessarily shown to scale with respect to each other.

[0066] In the figures, identical, functionally identical and acting identically elements, features and components are provided with the same reference symbols in each case (unless otherwise indicated).

[0067] Reference Figure 1 The first embodiment of the present apparatus is explained. Figure 1 A schematic diagram of an apparatus 100 according to the present disclosure is shown.

[0068] Device 100, in particular electronic device, is provided for monitoring the switchability of a load 50 connected to a first current path having power supply means 1, 3. Load 50 is coupled to device 100 via terminals 2, 4. Terminals 2, 4 represent outputs switchable by first adjusting element 10.

[0069] The first regulating element 10 is connected in the first current path and has an electrical connection to a voltage source. The first regulating element 10 can be designed as a field effect transistor.

[0070] The current carrying capacity of the first control element 10 can be variable by means of a first control signal 11. The first control signal 11 can be a current or a voltage.

[0071] The operating state of the first adjusting element 10 can be characterized by a first electrical variable, which is a first capacitance C on the first adjusting element. GS10and, as the case may be, a first voltage U measured by the voltage measuring device 30 GS10 .

[0072] The voltage measuring device 30 can detect / measure a first voltage U t across the gate-source path of the first adjustment element 10 . GS10 The voltage measuring device 30 can be designed as an operational amplifier which receives a voltage at an input.

[0073] Other embodiments of the voltage measuring device 30 may be provided, which detect and / or provide information about the first voltage U t across the gate-source path of the first adjusting element 10 . GS10 The first regulating element 10 is coupled to the voltage supply 1 by means of a drain connection. Furthermore, the first regulating element 10 is coupled to the consumer 50 by means of a source connection.

[0074] The device 100 has a second regulating element 20 in the second current path. The second regulating element 20 can be designed as a field effect transistor.

[0075] The second current path has a further current supply 5. The second adjusting element 20 is designed to provide a first adjusting signal 11 for controlling the first adjusting element 10. In particular, the first adjusting signal 11 is provided in the switching state of the second adjusting element 20.

[0076] The current carrying capacity of the second regulating element 20 can be changed by the second regulating signal 21. The second regulating signal 21 can be provided by the control device 60. The operating state of the second regulating element 20 can be characterized by a second electrical parameter, which is a second capacitance C on the second regulating element 20. GS20 And depending on the situation, it is the second voltage (gate-source voltage) U GS20 .

[0077] It is proposed that the first capacitance and the second capacitance are connected in series.

[0078] In particular, a capacitive voltage divider is provided which is formed by a first capacitance and a second capacitance. Thus, in this example, the drain-source capacitance and the gate-source capacitance of the second adjustment element 20 form a capacitive voltage divider.

[0079] In addition, a control device 60 is also provided in the device 100. The control device 60 can be designed as a microcontroller, FPGA, computer, SPS or similar control device. In particular, the control device 60 can be designed as a device with an interface 62, which is configured to receive signals / data and provide signals / data.

[0080] In particular, the control device 60 is configured to actuate the second actuating element 20 by means of the second actuating signal 21 at least in measuring intervals which are spaced apart from one another in time.

[0081] The second adjusting element 20 can be switched by providing a measuring pulse as the second adjusting signal 21, or switched to high resistance in the absence of a control signal 21. When the second adjusting element 20 is switched to high resistance, the charge of the barrier capacitance of the first adjusting element 10 is diverted to the capacitive voltage divider.

[0082] The divided voltage can be queried by the first voltage measuring device 30 and evaluated whether it is still within the range that is predetermined for fault-free shutdown. In the case of complete melting of the first adjusting element 10, the voltage will be outside the valid range. This can be used to diagnose that the first adjusting element 10 can no longer be shut down. Therefore, by evaluating the value obtained for the first electrical variable, a fault related to the shutdown of the first adjusting element 10 can be identified.

[0083] The evaluation of the obtained value of the first electrical variable comprises a comparison with at least one reference predetermined value.

[0084] The reference predetermined value(s) can be provided by means of resistive voltage dividers 52, 53, 54. The voltage 5 is applied to the resistive voltage dividers 52, 53, 54. The resistance values ​​can be selected such that the provided reference predetermined value can ensure a limit for the switchability of the first adjusting element 10.

[0085] The first and second voltage measuring devices 30, 40 can receive reference predetermined values ​​of the resistive voltage dividers 52, 53, 54. Furthermore, the first voltage measuring device 30 is coupled to the gate terminal of the first regulating element 10 in order to receive the first electrical variable.

[0086] The measurement may be performed by comparing a first electrical parameter including a gate-source voltage of the first regulating element 10 and a drain-source voltage of the second regulating element 20 with a reference predetermined value.

[0087] The two capacitive sections are compared to each other by measuring the voltage drop. If the capacitance of the gate-source section is smaller than the capacitance of the drain-source section, the gate-source voltage is greater than the drain-source voltage and the first regulating element 10 is allowed to remain controlled to be on.

[0088] The following two situations of complete melting leading to a failure of shutoff capability can be ensured to be safe by means of the device according to the present disclosure.

[0089] - Complete melting of the first adjusting element 10 may lead to a reduction in the barrier capacitance, which leads to a voltage increase via the capacitive voltage divider. A maximum reference predetermined value may be set for the increased value.

[0090] - Complete melting of the first regulating element 10 may result in gate closure and voltage reduction. A maximum reference predetermined value may be set for the reduced value.

[0091] Instead of an operational amplifier, an analog-to-digital converter may be provided.

[0092] The analog-to-digital converter can convert the detected first electrical parameter into a digital signal and provide it to the Figure 5 The control device 60 shown in FIG.

[0093] The control device 60 has, in particular, a processor unit 61 .

[0094] The processor unit 61 is designed to provide control signals in order to actuate the second adjusting element 20 at least in temporally spaced measurement intervals. The interface 62 is designed to provide control signals and to receive the value obtained for the first electrical variable of the first adjusting element 10 .

[0095] Furthermore, the processor unit 61 is designed to provide a control signal for evaluating a fault detection regarding a switch-off situation of the first adjusting element 10 , wherein the evaluation comprises comparing the obtained value regarding the first electrical variable with at least one reference predetermined value.

[0096] The control device 60 may have a memory unit 63 in which corresponding reference preset values ​​are stored.

[0097] The processor unit 61 of the control device 60 can compare the digital signal of the analog-to-digital converter with a stored reference predetermined value and issue a signal that a fault has been detected regarding the shutdown of the first adjusting element 10. The control device 60 can provide the signal so that it is forwarded to further components for outputting a warning.

[0098] Furthermore, control device 60 may also actuate further means for triggering a warning.

[0099] In one embodiment, reference Figure 1 It can be provided that a further capacitor 13 is connected in series with the capacitance to be measured (barrier capacitance) of the first adjustment element 10. As a result, the drain-source capacitance and thus the second adjustment element 20 can be designed to be smaller.

[0100] The further capacitance 13 can be switched by the second adjusting element 20. The capacitance 13 is selected such that in the capacitive voltage divider a corresponding voltage is still present at the first adjusting element 10, so that the capacitive voltage divider switches.

[0101] The barrier capacitance (gate-source) of the first adjustment element 10 and the further capacitance 13 can be dimensioned such that they are of the same order of magnitude, for example in the range between 100 pF and 10 nF.

[0102] If the second control element 20 is switched to high resistance, the charge of the barrier capacitance of the first control element 10 is divided to the capacitive voltage divider formed by the further capacitance 13 (instead of the capacitance of the drain-source path of the second control element 20). The magnitude of the divided voltage should be dimensioned such that the barrier capacitance is charged sufficiently to continue to control the first control element 10 to be turned on.

[0103] The divided voltage can be queried in terms of the range it should be in.

[0104] If the first control element 10 is completely melted, the voltage is outside the effective range, which allows for the assessment that the first control element 10 can no longer be switched off.

[0105] The device 10 is designed in such a way that the output is switched off when there is no voltage at the drain terminal of the second adjusting element 20. The switching-on energy is provided for the duration of the short test pulse. For this purpose, a resistor 51 can be provided, which is dimensioned in such a way that any failure of the second adjusting element 20 does not result in the first adjusting element 10 not switching off within a predetermined process safety time.

[0106] In an alternative design, it can be proposed to measure the change in drain-source voltage caused by the capacitive discharge. On the one hand, this can be done by means of an interconnection circuit that measures only the alternating voltage component; on the other hand, it can be done by means of a bandpass filter when switching off and on periodically with a certain frequency. The voltage may also be detected and measured using an analog-to-digital converter. In this respect, the barrier capacitance can be known by means of a different / additional measuring principle.

[0107] It can be provided that the capacitance is determined from the discharge curve instead of using a capacitive voltage divider. Figure 1 The capacitance C shown in DS20 If the barrier capacitance to be measured is very small (i.e. negligible as a first approximation) and no capacitor 13 is provided, but the resistor 51 is dimensioned to be suitable for this, the barrier capacitance can be determined by the discharge time. Here, a test pulse can be initiated and the time required for the voltage to drop below the reference value can be measured.

[0108] In alternative / supplementary design options, according to Figure 3 The device 100 has a third adjusting element 70 .

[0109] The third regulating element 70 is connected in series in the first current path with the first regulating element 10. If a voltage drop below a predetermined reference value is evaluated, the first regulating element 10 cannot be switched off any further.

[0110] The outputs 4 , 2 and / or the load 50 are switched off by means of a second switch-off path comprising the third adjusting element 70 . A fault message is output and a switch-on is prevented. The third adjusting element 70 can be actuated by the control device 60 .

[0111] Reference Figure 2 Another design of the device is explained. Here, it is based on the above reference Figure 1 The first embodiment of the device is explained; identical or identically acting elements are provided with the same reference numerals and are not described again in detail. Figure 2 A system 200 according to the present disclosure may be seen in FIG.

[0112] The system 200 has a first device and a second device 100 according to the present disclosure. The first device and the second device 100 are present in a duplicated manner and are arranged so that the negative pole of the first (upper) device (100) is coupled to the positive pole of the (lower) device 100. In addition, the system 200 also has an output terminal 201 for tapping the voltage on the negative pole. The first device 100 and the second device are coupled to a consumer 50.

[0113] In the design of the system 200, a second shutoff channel is provided. Since there are two devices 100 for switching the positive and negative channels, a second shutoff channel is still retained outside the device even in the event of a cross connection. If the consumer 50 is externally powered on the positive channel due to a fault, the second device 100 (as an M switch) still prevents the current from flowing. If a ground fault occurs on the negative channel of the consumer 50, the first device 100 (as a P switch) can still prevent the current from flowing.

[0114] Figure 4 A flow chart of a method according to the present disclosure is shown. Figure 4 , the reference symbol V denotes an embodiment of the method according to the present disclosure. The method V for monitoring the switchability has a plurality of method steps. The method V can be implemented by a processor unit 61 of a control device 60. In a first step S1, the second regulating element 20 is controlled at least at measuring intervals spaced apart from each other in time by means of a second regulating signal 21. In a second step S2, the value of the first electrical variable obtained here is evaluated to identify a fault related to the switch-off condition of the first regulating element 10.

[0115] List of Reference Numerals

[0116] 1.3 Current supply mechanism

[0117] 10. First regulatory element

[0118] 11 First adjustment signal

[0119] 13 Capacitor

[0120] 20 Second regulatory element

[0121] 21 Second adjustment signal

[0122] 30 Voltage measuring device

[0123] 40 Voltage measuring device

[0124] 50 Consumer

[0125] 51 Resistor

[0126] 52, 53, 54 Resistive voltage divider

[0127] 60 Control Equipment

[0128] 61 Processor Units

[0129] 62 Interface

[0130] 63 Memory Units

[0131] 70 Third regulating element

[0132] 71 Third adjustment signal

[0133] 100 devices

[0134] 200 systems

[0135] 201 Negative pole of voltage supply mechanism

[0136] V Method

[0137] S1-S2 Method Steps

Claims

1. A device (100) for monitoring the switchability of an electrical consumer (50) connected to a first current path having a current supply (1, 3), wherein: A first electrical regulating element (10) is arranged in the first current path, the current carrying capacity of the first regulating element being variable by means of a first regulating signal (11), wherein: The operating state of the first regulating element (10) is characterized by a first electrical parameter, wherein the first electrical parameter is a first capacitance (C GS10 ) and, if applicable, a first voltage (U GS10 ),in, The device (100) is provided with a second regulating element (20) for providing the first regulating signal (11) in a second current path having a further current supply device (5), wherein the current carrying capacity of the second regulating element can be changed by means of a second regulating signal (21), wherein: The operating state of the second regulating element (20) is characterized by a second electrical parameter, wherein the second electrical parameter is a second capacitance (C GS20 ) and, depending on the situation, the second voltage (U GS20 ),in, The first capacitance and the second capacitance are connected in series, and wherein, Furthermore, a control device (60) is provided, which is designed to control the second adjusting element (20) at least in measuring intervals spaced apart in time by means of the second adjusting signal (21) and to evaluate the value obtained in this respect for the first electrical variable in order to detect a fault in relation to the shutdown of the first adjusting element (10), and wherein: The evaluation comprises comparing the value obtained for the first electrical parameter with at least one reference predetermined value.

2. The device (100) according to claim 1, wherein A capacitor (13) is provided, and the capacitor (13) is coupled in parallel with the second regulating element (20) to increase the capacitance of the second regulating element (20).

3. The device (100) according to claim 2, wherein: The second capacitance or the second capacitance connected in parallel with the capacitor (13) has the same capacitance level as the first capacitance characteristic.

4. The device (100) according to claim 3, wherein: The capacitance level lies in the range of at least 100 pF to at most 10 nF.

5. The device (100) according to any one of claims 1 to 4, in, The first regulating element (10) and the second regulating element (20) are transistors, and the regulating signal is a control current or a control voltage (U GS10 , U GS20 ), It is proposed that the transistor is an n-channel or p-channel field effect transistor.

6. The device (100) according to any one of claims 1 to 4, wherein: The voltage measuring device (30) is designed as an operational amplifier or as an analog-to-digital converter and provides a digital signal to the control device (60) according to the value of the first electrical variable.

7. The device (100) according to any one of claims 1 to 4, in, The control device (60) is arranged to compare the value of the first electrical parameter with at least one first reference predetermined value and / or a second reference predetermined value, and The one or more reference predetermined values ​​are provided by a resistive voltage divider (52, 53, 54).

8. The device (100) according to any one of claims 1 to 4, wherein: In order to detect the absence of a fault with respect to the switching-off of the first switching element (10), the first electrical variable is reduced by a factor starting from a maximum value so that the first control element (10) is not switched off or remains switched off and a current sufficient to carry out the function of the consumer (50) flows through the consumer.

9. The device (100) according to any one of the preceding claims 1 to 4, wherein: A third regulating element (70) is arranged in the first current path, and the third regulating element (70) is connected in series with the first regulating element (10).

10. The device (100) according to claim 9, in order to identify a fault related to the shutdown of the first regulating element (10), the first electrical variable is reduced by a factor as much as possible from a maximum value without the first regulating element (10) being shut down, and a current sufficient to implement the function of the consumer (50) is prevented by means of the third regulating element (70).

11. The device (100) according to any one of claims 1 to 4, in, The device (100) also has a resistance element (51), and The first capacitance (C GS10 ) are connected in parallel.

12. A method (V) for monitoring the switchability of an electrical consumer (50) connected to a first current path having a current supply (1, 3), wherein: A first electrical regulating element (10) is arranged in the first current path, the current carrying capacity of the first regulating element being variable by means of a first regulating signal (11), wherein: The operating state of the first regulating element (10) is characterized by a first electrical parameter, wherein the first electrical parameter is a first capacitance (C GS10 ) and, as the case may be, a first voltage (U GS10 ),in, The device (100) is provided with a second regulating element (20) for providing the first regulating signal (11) in a second current path having a further current supply device (5), wherein the current carrying capacity of the second regulating element can be changed by means of a second regulating signal (21), wherein: The operating state of the second regulating element (20) is characterized by a second electrical parameter, wherein the second electrical parameter is a second capacitance (C GS20 ) and, depending on the situation, the second voltage (U GS20 ),in, The first capacitance and the second capacitance are connected in series, and wherein, The control device (60) controls (S1) the second adjusting element (20) at least in measuring intervals spaced apart in time by means of the second adjusting signal (21) and evaluates (S2) the value obtained in this process for the first electrical variable in order to detect a fault in relation to the shutdown of the first adjusting element (10), wherein: The evaluation comprises comparing the obtained value with a reference predetermined value.

13. A control device (60) for monitoring the switchability of an electrical consumer (50) connected via a first adjusting element (10) to a first current path having a current supply (1, 3), the first current path being located in a device (100) according to one of claims 1 to 11, the control device (60) being further designed to carry out the method according to claim 12, the control device comprising: a processor unit (61) designed to provide control signals in order to actuate the second adjusting element (20) at least at measuring intervals spaced apart in time from one another; as well as - an interface (62) designed to provide control signals and to receive the value obtained for a first electrical variable of the first regulating element (10); - wherein the processor unit (61) is also designed to provide a control signal in order to evaluate a fault detection regarding a switch-off situation of the first regulating element (10), and - wherein said evaluation comprises comparing the value obtained for said first electrical parameter with at least one reference predetermined value.

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