Controlling an electromechanical switch and a semiconductor switch

Abstract

The invention relates to an arrangement with an electromechanical switch (1), a semiconductor switch (2) and a control device (3), wherein the electromechanical switch (1) and the semiconductor switch (2) can be switched on and off, wherein the electromechanical switch (1) and the semiconductor switch (2) are each closed in the switched-on state and each open in the switched-off state, the electromechanical switch (1) has switching contacts (4) which can be electromechanically connected to one another for switching on and off, the electromechanical switch (1) and the semiconductor switch (2) are connected in series to one another in a load path (5) and both can be switched on and off.Switching off are connected to the control device (3), and the control device (3) is configured such that, when the electromechanical switch (1) and the semiconductor switch (2) are switched off to open the load path (5), it first sends a switch-off signal to the electromechanical switch (1) and then, after a predetermined switch-off delay, a switch-off signal to the semiconductor switch (2). This solves the problem of enabling the switching of higher currents at DC voltages, which would lead to persistent arcs in a conventional relay when switched off.

Description

The invention relates to an arrangement having an electromechanical switch, a semiconductor switch and a control device, wherein the electromechanical switch and the semiconductor switch can be switched on and off, wherein the electromechanical switch and the semiconductor switch are each closed in the switched-on state and are each open in the switched-off state, the electromechanical switch has switching contacts which can be connected to one another electromechanically for switching on and off, and the electromechanical switch and the semiconductor switch are connected in series to one another in a load path and are both connected to the control device for switching on and off. The invention also relates to a method for controlling an electromechanical switch and a semiconductor switch, wherein the electromechanical switch has switching contacts which can be connected to one another electromechanically for switching on or switching off, and the electromechanical switch and the semiconductor switch are connected in series with one another in a load path, and electromechanical switch and the semiconductor switch are connected to the control device for switching on or switching off.So-called HIL simulators are known from the prior art, which are used in particular for testing control units ("HIL" derived from "hardware in the loop"). HIL simulators each comprise at least one computer unit, wherein the computer unit or the computer units have in particular the task of executing models which at least partially simulate an environment of an electronic device or of a more complex technical system.HIL simulators thus make possible a test method in which an embedded system, in particular an electronic control unit (ECU) or a mechatronic module, is connected via its inputs and outputs to an adapted counterpart, namely the HIL simulator, which serves to simulate the real environment of the embedded system. The embedded system is also referred to as a device under test (DUT) within the scope of an HIL simulation. During the test of the embedded system, at least a portion of the input signals for the embedded system are thus provided by the HIL simulator and at least a portion of the output signals of the embedded system are sent to the HIL simulator.For example, by means of an environment model which is executed on an HIL simulator, the temporal behavior of the environment of the system under test can be simulated. If, for example, an HIL simulator is to test an embedded system, in particular a control device, then the HIL simulator is designed as an at least partial replica of the real environment of the control device. The HIL simulator can thus communicate with the control device in this case via its inputs and outputs or bidirectional communication channels equipped with a bus or network interface and thus function as an adapted counterpart of the control device.The HIL simulation is always only a simplification of the reality and therefore cannot replace the test on the real system. If too great discrepancies occur between an HIL test and reality, the underlying models in the simulation are often too much simplified. The simulation models must then be developed further.An essential component of HIL tests are fault simulations in order to test the reaction of the control unit in fault situations. In order to simulate cable breaks or similar faults, additional plug-in cards for HIL systems or external devices, which can also be connected to the HIL systems via bus or network interfaces, for example, are usually available, so-called failure insertion units (FIUs), also referred to as fault introduction units. They comprise circuits with remotely and automatically controllable switches for simulating, for example, cable breaks, short circuits and / or a so-called contact bounce (bounce within the scope of the above-mentioned errors, "wobble contact"), which can lead to an undesired modulation. FIUs exist for sensors as well as actuators, wherein they are additionally combined with load devices for actuators. Therefore, simulation signals can be generated by the FIUs in particular which represent non-normal, i.e. defective, operating states. Thus, an electrical component can be tested not only with regard to a regulating operation, but also with regard to various fault and / or interference states.DE 10 2009 048 981 A1 of dSPACE GmbH describes an FIU in the form of a device for testing an electronic component having a simulation device for generating a simulation signal, a test device for connecting the electronic component, two connecting devices and a selection device for selecting the connecting device, wherein the simulation device and the test device can be electrically conductively connected to one of the connecting devices by means of the selection device and the individual connecting devices differ from one another in each case with respect to at least one electrical property. The simulation device is configured such that simulation signals for different operating states of the electronic component can be generated and, in particular, simulation signals for faulty operating states of the electrical component can be provided by means of an FIU.In such an FIU, the signal lines are typically connected to the ground potential or the positive potential line, i.e. to 0 V or to up to +60 V, so that an object to be tested can be supplied with a corresponding voltage. For this voltage application, e.g. semiconductor switches such as MOSFET switches can be provided, which, however, should be protected in the event of potential overloads. The load path can also be interrupted in order to simulate a cable break.On the basis of this, it is the object of the invention to further develop the prior art. Preferably, the switching of higher currents at DC voltages is to be made possible, which in a conventional relay would lead to continuous arcs when switching off.This object is achieved by the subject matters of the independent claims. Preferred refinements are found in the dependent claims.According to the invention, an arrangement comprising an electromechanical switch, a semiconductor switch and a control device is thus provided, wherein the electromechanical switch and the semiconductor switch can be switched on and off, wherein the electromechanical switch and the semiconductor switch are each closed in the switched-on state and are each open in the switched-off state, the electromechanical switch has switching contacts which can be connected to one another electromechanically for switching on or switching off, the electromechanical switch and the semiconductor switch are connected in series to one another in a load path, and electromechanical switch and the semiconductor switch are connected to the control device for switching on or switching off, and the control device is configured in such a way, When the electromechanical switch and the semiconductor switch are switched off to open the load path, it first sends a switch-off signal to the electromechanical switch and then after a predetermined switch-off delay sends a switch-off signal to the semiconductor switch.Such an arrangement can be used together with an electronic fuse to open the electronic switch in the event of overload.The last-mentioned series connection of electromechanical switches and semiconductor switches in the load path leads to an advantage compared to a circuit or series connection which has / have exclusively one semiconductor switch or exclusively a plurality of semiconductor switches in the load path. The advantage consists in avoiding a disadvantage which is caused by the intrinsic electrical capacitance present between the normally open contacts (for example between source and drain) in a semiconductor switch and which is significantly higher in comparison in the switched-off state of the semiconductor switch. An electromechanical switch avoids the unwanted effect of the last-mentioned electrical capacitance in the series connection with the semiconductor switch. Otherwise, i.e. without using an electromechanical switch in the load path, the intrinsic capacitance of the semiconductor switch in FIU applications can in particular impair or prevent realistic replication (HIL simulation) of a signal interruption.Fundamentally different settings are suitable for the shutdown delay. According to a preferred development of the invention, however, the switch-off delay is selected such that it leads to a time-limited arc between the switching contacts of the electromechanical switch. This arc serves to clean the switching contacts of the electromechanical switch.Preferably, the electromechanical switch has an intrinsic switching time for the switching off, which is given by the time duration between the receipt of the switching-off signal from the control device and the opening of the electromechanical switch, and the switching-off delay is greater than the intrinsic switching time of the electromechanical switch. In the present case, such an electromechanical switch is preferably used, which is also suitable for 50 Hz / 250 volt AC applications in addition to DC applications. The maximum arc burning time is preferably selected to be shorter than the duration of a mains half-wave of 10 ms. The switch-off delay is preferably selected such that the arc occurs between the switching contacts of the electromechanical switch for a maximum of 7 ms.According to a preferred development of the invention, it is also true that the electromechanical switch for suppressing arcs has neither a structural configuration nor a function.As regards the switching-on, it is preferably the case that the control device is configured such that, when the electromechanical switch and the semiconductor switch are switched on, it simultaneously sends a respective switching-on signal to the electromechanical switch or the semiconductor switch. However, it is the case here that the simultaneous switch-on signals, caused by the physical differences between a semiconductor switch on the one hand and an electromechanical switch on the other hand, generally do not lead to the semiconductor switch and the electromechanical switch actually also being closed simultaneously. Rather, the simultaneous switch-on signals generally result in the semiconductor switch being closed upstream of the electromechanical switch, that is to say the semiconductor switch providing an electrically conductive connection upstream of the electromechanical switch.Preferably, the semiconductor switch is a MOSFET switch. This can be designed for switching one technical current direction, or preferably for switching both technical current directions. It is also preferred that the electromechanical switch is a relay or a contactor.In principle, the semiconductor switch can be used for only one electromechanical switch. According to a preferred development of the invention, however, the semiconductor switch is connected in series upstream of a plurality of electromechanical switches which are connected in parallel with one another and are all connected to the control device for switching on or off, wherein the control device is configured such that only one of the electromechanical switches can be switched on simultaneously.The invention also relates to a failure insertion unit for connection to an HIL simulator via a load path and for simulating at least one electrical fault and transmitting it to the HIL simulator via the load path, wherein the load path is provided with an arrangement described above. The electrical fault is preferably selected from the group comprising a short circuit of a control device output to ground potential, a short circuit of a control device output to supply potential and a short circuit of a control device output having a first signal line to a second signal line, and a disconnection of a signal line which electrically connects a control device output to a signal sink or a control device input to a signal source. Most preferably, the error introduction unit FIU can deliver a plurality of errors.The aforementioned short circuits represent fault cases which are brought about for simulation purposes, namely triggered under computer program control. The fail-insert unit is preferably connected to a real control device, namely to its real control device outputs. In the absence of availability of a real control device, it is preferred that a simulated control device with simulated control device outputs is used. According to a preferred development of the invention, mixed forms are also used, namely in such a way that genuine control units are interconnected together in a network with simulated control units and selected genuine and / or simulated control unit outputs are connected to the failure insertion unit.The invention further relates to a method for controlling an electromechanical switch and a semiconductor switch, wherein the electromechanical switch and the semiconductor switch can be switched on and off, wherein the electromechanical switch and the semiconductor switch are each closed in the switched-on state and are each open in the switched-off state, the electromechanical switch has switching contacts which can be connected to one another electromechanically for switching on and off, and the electromechanical switch and the semiconductor switch are connected in series to one another in a load path and are both connected to the control device for switching on and off, having the following method steps:sending a shutdown signal to the electromechanical switch at a first time; andsending a shut-down signal to the semiconductor switch at a second time that is delayed from the first time by a predetermined shut-down delay.In this case, according to a preferred development of the invention, it is provided that the control device simultaneously sends a respective switch-on signal to the electromechanical switch or the semiconductor switch when the electromechanical switch and the semiconductor switch are switched on.Further preferred embodiments of this method are obtained analogously to the further above-described preferred embodiments of the arrangement according to the invention. Very particular preference is given to using these methods for a failure insertion unit.The invention is explained in more detail below on the basis of preferred exemplary embodiments with reference to the drawings.In the drawings, FIG. 1 schematically shows an arrangement with an electromechanical switch, a semiconductor switch and a control device in a failure insertion unit according to a preferred embodiment of the invention, FIG. 2 shows the control of the electromechanical switch and the semiconductor switch during the switching-on and the switching-on reactions of the electromechanical switch and the semiconductor switch according to the preferred exemplary embodiment of the invention, FIG. 3 shows the control of the electromechanical switch and the semiconductor switch during the switching off and the switching off reactions of the electromechanical switch and the semiconductor switch according to the preferred exemplary embodiment of the invention, and FIG. 4 schematically shows an arrangement with a plurality of electromechanical switches, a semiconductor switch and a control device according to a further preferred exemplary embodiment of the invention.FIG. 1 schematically shows an arrangement with an electromechanical switch 1 in the form of a relay, a semiconductor switch 2 designed as a MOSFET switch and a control device 3 according to a preferred exemplary embodiment of the invention. The electromechanical switch 1 and the semiconductor switch 2 can both be switched on and off, wherein the electromechanical switch 1 and the semiconductor switch 2 are each closed in the switched-on state and are each open in the switched-off state. The electromechanical switch 1 has switching contacts 4 which can be connected to one another electromechanically and which are contacted with one another or disconnected from one another for switching the electromechanical switch 1 on or off, in order in this way to establish or disconnect a galvanically conductive connection.The electromechanical switch 1 used in the present case has neither a structural configuration nor a function for suppressing arcs. The electromechanical switch 1 and the semiconductor switch 2 are connected in series with one another in a load path 5. In addition, the electromechanical switch 1 and the semiconductor switch 2 are connected to the control device 3, so that the electromechanical switch 1 and the semiconductor switch 2 can be controlled by the control device 3 for switching on and off.An exemplary embodiment is shown here in which the arrangement with the electromechanical switch 1, the semiconductor switch 2 and the control device 3 is part of a failure insertion unit 6. The failure insertion unit 6 is provided for connection to an HIL simulator, not shown in any more detail here, via the load path 5. The failure insertion unit 6 used here can generate the following electrical faults, among other things, and output them to the HIL simulator: a short circuit of a control device output to ground potential, a short circuit of a control device output to supply potential, a short circuit of a control device output having a first signal line to a second signal line, and a break-up of a signal line which electrically connects a control device output to a signal sink or a control device input to a signal source.As can be seen schematically from FIG. 2, which shows the actuation of the electromechanical switch 1 and of the semiconductor switch 2 when switching on and the switching-on reactions of the electromechanical switch 1 and of the semiconductor switch 2, a respective switching-on signal is transmitted simultaneously by the control device 3 to the electromechanical switch 1 and the semiconductor switch 2 when switching on the electromechanical switch 1 and the semiconductor switch 2 (switching profiles a and b). However, this does not lead to an immediate switching on of the electromechanical switch 1 and the semiconductor switch 2 nor to the electromechanical switch 1 and the semiconductor switch 2 closing at the same time. Rather, the semiconductor switch 2 has a very low reaction time of approximately 10 μs, while the reaction time of the electromechanical switch 1 is in the range between 1 and 6 ms. The electromechanical switch 1 (switch-on profile c) thus closes substantially later than the semiconductor switch 2 (switch-on profile d).An essential aspect of the preferred exemplary embodiment of the invention described in the present case is now that, as is schematically shown in FIG. 3, the control device 3 sends a switch-off signal to the electromechanical switch 1 (switching profile a) only when the electromechanical switch 1 and the semiconductor switch 2 are switched off in order to open the load path 5 and sends a switch-off signal to the semiconductor switch 2 (switching profile b) only thereafter, namely after a predetermined switch-off delay. The switch-off delay is selected in such a way that it leads to a time-limited arc between the switching contacts 4 of the electromechanical switch 1. It should be taken into account that the electromechanical switch 1 has an intrinsic, i.e. unavoidable, switching time for the switching off, which is given by the time duration between the reception of the switching-off signal from the control device 3 and the opening of the electromechanical switch 1. In the preferred exemplary embodiment described here, an arc is therefore formed between the switching contacts 4 of the electromechanical switch 1 for a time duration of a maximum of 7 ms.Finally, FIG. 4 schematically shows an arrangement having a plurality of electromechanical switches 1, a semiconductor switch 2 and a control device 3 according to a further preferred exemplary embodiment of the invention. The semiconductor switch 2 is connected to the control device 3 via a semiconductor control line, which is not shown in FIG. 4. As shown, the semiconductor switch 2 is connected in series upstream of a plurality of electromechanical switches 1 connected in parallel to one another, all of which are connected to the control device 3 for switching on or off. In this case, the control device 3 is set such that only one of the electromechanical switches 1 can be switched on simultaneously. Otherwise, the function for the individual electromechanical switches 1 is as explained above with reference to FIGS. 1, 2 and 3.List of reference characters1 Electromechanical switch 2 Semiconductor switch 3 Control device 4 Switching contacts 5 Load path 6 Failure Insertion UnitReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2009 048 981 A1

[0007]

Claims

Arrangement having an electromechanical switch (1), a semiconductor switch (2) and a control device (3), wherein the electromechanical switch (1) and the semiconductor switch (2) can be switched on and off, wherein the electromechanical switch (1) and the semiconductor switch (2) are each closed in the switched-on state and are each open in the switched-off state, the electromechanical switch (1) has switching contacts (4) which can be connected to one another electromechanically for switching on or off, the electromechanical switch (1) and the semiconductor switch (2) are connected in series with one another in a load path (5), and electromechanical switch (1) and the semiconductor switch (2) are connected to the control device (3) for switching on or off, and the control device (3) is configured in such a way, In that, when the electromechanical switch (1) and the semiconductor switch (2) are switched off to open the load path (5), it first sends a switch-off signal to the electromechanical switch (1) and then, after a predetermined switch-off delay, sends a switch-off signal to the semiconductor switch (2).Arrangement according to Claim 1, wherein the switch-off delay is selected such that it leads to a time-limited arc between the switching contacts (4) of the electromechanical switch (1).Arrangement according to Claim 2, wherein the switch-off delay is selected such that the arc is formed between the switching contacts (4) of the electromechanical switch (1) for a time duration of at most 7 ms.Arrangement according to one of the preceding claims, wherein the electromechanical switch (1) has an intrinsic switching time for the switching off, which is given by the time duration between the reception of the switching-off signal from the control device (3) and the opening of the electromechanical switch (1), and the switching-off delay is greater than the intrinsic switching time of the electromechanical switch (1).Arrangement according to one of the preceding claims, wherein the electromechanical switch (1) for suppressing arcs has neither a structural configuration nor a function.Arrangement according to one of the preceding claims, wherein the control device (3) is configured such that, when the electromechanical switch (1) and the semiconductor switch (2) are switched on, it simultaneously sends a respective switch-on signal to the electromechanical switch (1) or the semiconductor switch (2).Arrangement according to one of the preceding claims, wherein the semiconductor switch (2) is a MOSFET switch.Arrangement according to one of the preceding claims, wherein the electromechanical switch (1) is a relay or a contactor.Arrangement according to one of the preceding claims, wherein the semiconductor switch (2) is connected in series upstream of a plurality of electromechanical switches (1) which are connected in parallel with one another and are all connected to the control device (3) for switching on or switching off, and the control device (3) is configured such that only one of the electromechanical switches (1) can be switched on simultaneously.A failure insertion unit (6) for connection to an HIL simulator via a load path (5) and for simulating at least one electrical fault and transmitting it to the HIL simulator via the load path (6), wherein the load path (6) is provided with an arrangement according to one of the preceding claims.The fail-insert unit (6) according to claim 10, wherein the electrical fault is selected from the group comprising a short circuit of a control device output to ground potential, a short circuit of a control device output to supply potential and a short circuit of a control device output having a first signal line to a second signal line, and a break-up of a signal line electrically connecting a control device output to a signal sink or a control device input to a signal source.Method for controlling an electromechanical switch (1) and a semiconductor switch (2), wherein the electromechanical switch (1) has switching contacts (4) which can be connected to one another electromechanically for switching on or switching off, and the electromechanical switch (1) and the semiconductor switch (2) are connected in series with one another in a load path (5) and are both connected to the control device (3) for switching on or switching off, having the following method steps: sending a switch-off signal to the electromechanical switch (1) at a first point in time and sending a switch-off signal to the semiconductor switch (2) at a second point in time which is delayed by a predetermined switch-off delay compared to the first point in time.Method according to Claim 12, wherein the control device (3) simultaneously sends a respective switch-on signal to the electromechanical switch (1) or the semiconductor switch (2) when the electromechanical switch (1) and the semiconductor switch (2) are switched on.Use of a method according to one of claims 12 or 13 for a failure insertion unit (6).

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