Method and control unit for controlling an electrical component and device for controlling an electrical component

Abstract

The approach presented here provides a method (400) for controlling an electrical component (105), wherein the method (400) comprises a step of impressing (410) a current flow with a predefined maximum current intensity (I1) to the electrical component (105) by a current source (120) and a step of closing (420) a switch (140) connected in parallel to the current source (120) in order to supply the electrical component (105) with energy from a power supply connection (125) in order to control the electrical component (105).

Description

[0001] The present invention relates to a method and a control unit for controlling an electrical component and to a device for controlling an electrical component according to the main claims.

[0002] Engine and hydraulic control units are often designed to switch inductive loads. For this purpose, an n-channel MOSFET, for example, is controlled and monitored by an integrated circuit. Applicable safety standards require permanent protection of this exemplary MOSFET against short circuits and overcurrents. To detect overcurrents and short circuits, the drain-source voltage of the MOSFET is often monitored. In the event of a short circuit, the MOSFET should be switched off very quickly to prevent thermal overload. However, when switching capacitive loads, halogen lamps, and LED lights, very high inrush currents are generated for a short time. These can falsely suggest a short circuit to diagnostic devices, which are often designed for inductive loads, and lead to the unintentional shutdown of the MOSFET.The drain-source voltage monitoring described above cannot distinguish between a true short circuit and a temporary inrush current. The output MOSFET diagnostics are falsely triggered each time the device is turned on. Suppressing the diagnostics would potentially destroy the MOSFET in the event of a short circuit. Using this approach, it is therefore not possible to switch capacitive loads or lamps without incurring a diagnostic gap that could result in MOSFET destruction.

[0003] It is the object of the present invention to provide a possibility for improving the control of an electrical component, in particular in the case of a capacitive load.

[0004] This object is achieved by a method, a control unit and a device according to the main claims.

[0005] The approach presented here provides a method for controlling an electrical component, the method comprising the following steps: - Impressing a current flow with a predefined maximum current intensity to the electrical component by a current source; and - Closing a switch connected in parallel to the power source to supply the electrical component with energy from a power supply terminal to drive the electrical component.

[0006] In this case, an electrical component can be understood as a consumer, for example a capacitive load or a lamp, especially one that requires a high starting current. For example, in a lamp, especially an incandescent lamp, a heating of a filament may be necessary, so that this wire is heated first before the lamp can fulfill its actual function of emitting light. However, this heating of the wire requires a large current flow, which could also be interpreted as a short circuit in the electrical component. A capacitive load could, for example, be understood as an energy storage device such as a supercapacitor that is to be charged and, for example, has a high current consumption when discharged. A current source in this case can be understood as a technical or electrical component that is capable of outputting a defined current at various applied voltages.The power source should be designed or configured in such a way that no components of the electrical component are destroyed during the expected on-time of the electrical component, or the predefined maximum current is lower than a short-circuit current threshold, above which a short circuit and thus a fault in the electrical component and / or switch is detected or assumed. For this purpose, the power source can also be designed to deliver current depending on the parameters of the electrical component.

[0007] The approach presented here is based on the insight that by first imposing a current flow at the predefined maximum current intensity on the electrical component, the electrical component is prepared for subsequent commissioning. This can be done, for example, by activating processes within the electronic component that would otherwise require or permit a high current flow, such as heating a wire in a lamp or heating a conductor or resistor in a load. This prepares the electrical component for subsequent opening of the switch in such a way that a high starting current is no longer expected.In this case, it can also be largely avoided that a corresponding fault protection circuit triggers an immediate shutdown, since this fault protection circuit assumes that a high starting current is a short circuit in the electrical component and / or switch and is intended to prevent (further) damage to the electrical component or the switch by means of this immediate shutdown.

[0008] The approach presented here thus offers the advantage of avoiding unwanted or faulty shutdown or decommissioning of the electrical component by previously imposing the current flow at the predefined (maximum) current intensity on the electrical component. This significantly increases the acceptance of a technical system with the approach presented here, using the method, control unit, or device presented here.

[0009] Another advantageous embodiment of the approach proposed here is one in which the impressing step is performed within a period of at most one second, in particular of at most 100 milliseconds, preferably of at most 10 milliseconds, before the opening step. Specifically, impressing the predefined maximum current within a period immediately before opening the switch thus enables rapid preparation of the electrical component for commissioning.

[0010] A particularly advantageous embodiment of the approach proposed here is one in which a power semiconductor switch is opened as a switch in the opening step, in particular wherein the power semiconductor switch is configured as a MOSFET, a thyristor, or an IGBT. Such an embodiment offers the advantage that the use of such a switch type enables a cost-effective and reliable way of switching on or activating the electrical component.

[0011] According to another embodiment of the approach proposed here, a current source comprising a transistor circuit, in particular a bipolar transistor circuit, can also be used in the imprinting step. Such an embodiment offers the advantage of a cost-effective implementation of the current source, which also operates quickly and reliably.

[0012] An embodiment of the approach proposed here can also be implemented in a technically simple manner. In this embodiment, an (e.g., integrated) electronic component having a thermal overload protection device is used as the current source in the imprinting step. In particular, the thermal overload protection device is designed to switch off the electronic component at a maximum electrical power that is less than the rated transmission line of the switch. Due to the thermal inertia of the thermal overload protection device, it is still possible to switch inrush currents without triggering the thermal diagnosis. The current or power can be very high for a short time (e.g., significantly higher than the rated power of the MOSFET). After the inrush event, the MOSFET, which is located on the cooling bench, can be used as the switch. This means that the requirements of the electronic component or the SmartFET are not high.In principle, conventional MOSFETs are significantly smaller and their rated power is significantly higher than that of a SmartFET. This allows the advantages of both switching elements to be combined. This design offers the advantage that mature and widely available electronic components can be used for the power source, which already feature appropriate thermal overload protection. This also makes it possible to protect the switch or the electrical component against thermal overload.

[0013] In particular, according to a favorable embodiment, a power source whose heat dissipation is independent of a heat sink of the switch and / or the electrical component can be used in the imprinting step. Such an embodiment offers the advantage of being able to design the heat dissipation of the power source independently of the heat dissipation option or the heat sink of the switch and / or the electrical component, which offers additional design freedom in the development of a technical implementation of the approach presented here.

[0014] The approach presented here can be used particularly favorably and advantageously in an embodiment in which, during the opening step, an electrical component formed by a capacitive load and / or a lamp, in particular a halogen lamp and / or an LED, is supplied with energy from the power supply connection. The aforementioned high starting currents occur particularly with such loads or lamps, and their misinterpretation can be avoided or reduced as much as possible using the procedure described above.

[0015] According to one embodiment, a step of deactivating the power source can also be provided after the opening step, in particular wherein the deactivation step occurs within a time interval of 1 second after the opening step. Such an embodiment offers the advantage that, by switching off the power source, a targeted and unambiguous power supply to the electrical component is possible by a single control element, without requiring power from the power source.

[0016] The approach presented here further provides a control unit configured to perform, control, or implement the steps of a variant of a method presented here in corresponding devices. This embodiment of the invention in the form of a control unit also allows the problem underlying the invention to be solved quickly and efficiently.

[0017] For this purpose, the control unit can have at least one computing unit for processing signals or data, at least one memory unit for storing signals or data, at least one interface to a sensor or an actuator for reading sensor signals from the sensor or for outputting control signals to the actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The computing unit can be, for example, a signal processor, a microcontroller, or the like, wherein the memory unit can be a flash memory or a magnetic storage unit.The communication interface can be designed to read in or output data wirelessly and / or via a wired connection, wherein a communication interface that can read in or output wired data can read this data, for example, electrically or optically from a corresponding data transmission line or output it to a corresponding data transmission line.

[0018] In this case, a control unit can be understood as an electrical device that processes sensor signals and outputs control and / or data signals depending on them. The control unit can have an interface that can be implemented in hardware and / or software. In a hardware implementation, the interfaces can, for example, be part of a so-called system ASIC, which contains a wide variety of functions of the control unit. However, it is also possible for the interfaces to be separate integrated circuits or to consist at least partially of discrete components. In a software implementation, the interfaces can be software modules that are present, for example, on a microcontroller alongside other software modules.

[0019] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular when the program product or program is executed on a computer or a device.

[0020] The above-mentioned advantages can also be realized by a device for controlling an electrical component, the device having the following features: - a current source for impressing a current flow with a predefined maximum current intensity on the electrical component; - a switch connected or switchable in parallel with the power source, which switch is designed to supply the electrical component with energy from a power supply connection in order to control the electrical component; and - a control unit according to a variant presented here.

[0021] The invention is explained in more detail below with reference to the accompanying drawings. They show: Fig. 1 is a schematic representation of an embodiment of a device for controlling an electrical component; and Fig. 2A is a diagram of a current waveform over time as it would be without the use of the according to the representation of Fig. 1 device including the power source; Fig. 2B is a diagram of a current curve over time, as it is now with the use of the according to the representation from Fig. 1 device shown with the power source; Fig. 3 a circuit diagram illustrating the exemplary structure of a current source as it can be used in a device for controlling an electrical component Fig. 4 a flowchart of an embodiment of the present invention as a method for controlling an electrical component.

[0022] Identical or similar elements may be provided with identical or similar reference numerals in the following figures. Furthermore, the figures of the drawings, their description, and the claims contain numerous features in combination. A person skilled in the art will appreciate that these features may also be considered individually or combined to form further combinations not explicitly described here.

[0023] Fig. 1 shows a schematic representation of an embodiment of a device 100 for controlling an electrical component 105. The electrical component 105 can be configured as a capacitive load and / or as a lamp, which requires a high starting current for commissioning. For example, such a capacitive load can be a supercapacitor or another electrical energy storage device that has a high current consumption during charging in an early stage of such a charging process. The electrical component 105 can also be configured as a lamp, in which a filament must be specifically preheated, which initially requires a current flow with a high current intensity.In order to avoid that such a high starting current is interpreted as a fault, specifically a short circuit in the electrical component 105, which would then lead to a shutdown of the electrical component 105 by a safety circuit, the use of the device 100 presented here for controlling the electrical component can now provide a remedy.

[0024] To avoid such a high starting current, a control unit 110 with a stamping unit 115 first controls a current source 120, which applies a predetermined maximum current I1 from a supply voltage connection 125 via a resistor 130, for example a shunt resistor, into this electrical component 105. In this way, for example, capacitances in the electrical component 105 can be precharged or a corresponding filament in an electrical component 105 configured as a lamp can be preheated. This ensures that the current flowing into the electrical component 105 does not exceed a certain threshold value, which could, for example, trigger safety devices and mistakenly consider the electrical component 105 to be defective.

[0025] After a certain period of time, for example, ten or 100 milliseconds, a closing unit 135 of the control unit 110 can control and close a switch 140 or Q4, which is connected, for example, in parallel with the current source 120 between the supply voltage terminal 125 and the electrical component 105 or the resistor 130. Via this switch 140, which is configured, for example, as a MOSFET power semiconductor component, the current flow can now be conducted from the supply voltage terminal 125 into the electrical component 105 without requiring a current limit.By “precharging” the electrical component 105 with the maximum current I1 supplied by the current source 120, the otherwise occurring high current peak can be intercepted, so that the probability of an incorrect assessment of the electrical component 105 due to a high initially occurring current intensity can be largely avoided.

[0026] Fig. Figure 2A shows a graph of a current waveform over time as it would be without the use of the Fig. 1, including the current source 120. Here, the graph 200 represents the current flow through the electrical component 105 over time. In a first section 205, in which the switch 140 is open. At a first time 210, the switch is closed, resulting in a sharp increase in the current flow, which, for example, at time 212 rises above the short-circuit current threshold 215, so that a corresponding protective circuit, which is provided in the Fig. 1 is not shown in detail, the electrical component 105 is considered to be faulty, even if this is not the case, but the high starting current 220 merely serves to pre-charge capacitances in the electrical component 105 and drops below the short-circuit threshold value 215 shortly after it has been exceeded.

[0027] Fig. Figure 2B shows a diagram of a current curve over time, as it is now obtained using the current curve shown in Fig. 1 with the power source 120. In the time interval 205, the switch 140 and the power source 120 are again switched off. If at the first time 210 the electrical component 105 is switched on according to the Fig. 1 is activated, the current source 120 is activated in the first step, so that a maximum current flow I1 is impressed into the electrical component 105, which is significantly lower than a current flow according to the short-circuit threshold 210, for example, corresponding to half of this short-circuit threshold 210. At a second time 230, which is, for example, 10 to 100 milliseconds after the first time 210, the switch 140 is now closed by a corresponding control signal, so that a main current flow now flows from the supply connection 125 to the electrical component 105 via this switch 140. As can be seen from the Fig. As can be seen in Figure 2B, a smaller current peak or starting current 220 will now also occur, but its current intensity will not exceed the short-circuit current threshold 215, so that in this case, no fault will be detected by a corresponding protective circuit. This can now significantly increase the convenience of operating capacitive loads or lamps, as the probability of an incorrect assessment can now be significantly reduced.

[0028] Fig. 3 shows a circuit diagram illustrating the exemplary structure of a current source 120, as may be used in a device 100 for driving an electrical component 105. According to this circuit diagram, it can be seen that the current source 120 comprises a first bipolar transistor Q5 and a second bipolar transistor Q4, as well as a shunt regulator D1. A less precise bipolar transistor could also be used for the shunt regulator. The first bipolar transistor Q5 is designed as an NPN transistor, with its collector connected to the supply voltage 125 and its emitter connected to the electrical component 105 via a resistor R7.The second bipolar transistor Q4 is designed as a PNP transistor, wherein its emitter is connected to the supply claim 120 via a resistor R5 and its collector is connected to the base terminal of the first bipolar transistor Q5 and the cathode of the shunt regulator D1. The anode of the shunt regulator D1 is also connected to or can be used with the electrical component 105. Furthermore, a control terminal of the shunt regulator D1 is connected to the emitter of the first transistor Q5. The emitter of the second transistor Q4 is connected via a resistor R4 to the control terminal or base terminal of the second transistor Q4. Furthermore, a third bipolar transistor Q1 is provided, which is designed as an NPN transistor and whose collector is connected to the base terminal of the second transistor Q2 via a resistor R3. The emitter of the third transistor Q1 is connected to a ground terminal, whereas the control orThe base terminal of the third transistor Q1 is coupled to the impression unit 115 via a resistor R3.

[0029] It is further conceivable that the device 100 and / or the power source 120 is configured to detect that a fault is present in the electrical component 105, for example an internal short circuit. Such detection of an internal connection or fault in the electrical component 105 can occur, for example, by varying the current intensity and / or the voltage applied to the electrical component 105 after a certain period of time and by evaluating a reaction of the current flow through the electrical component in response to this variation in the current intensity or the voltage. In this way, despite the optimized precharging of the electrical component 105, a fault in the electrical component 105 can be reliably detected, whereby, for example, damage to components of the system used, specifically the device 100 and / or the electrical component 105, can be avoided.

[0030] The current source 120 can further be implemented by a correspondingly configured electronic circuit that has a thermal overload protection device. In this case, it can be recognized, for example, that an excessively high (maximum) current flow I1 through this electronic circuit would result in damage to this electronic circuit as the current source 120, so that the current flow I1 is limited or completely shut off, for example, by this thermal overload protection device. In this way, damage to, for example, the switch 140 and / or the electrical component 105 can be reliably avoided or ruled out.

[0031] In summary, with a voltage-monitored MOSFET as a switch such as switch 140 in the Fig. 1 the voltage drop across RDS(on) is continuously monitored. The voltage drop is proportional to the load current. In the event of a short circuit in switch 140 and / or the electrical component 105, depending on the short-circuit impedance, very high currents with an extremely short rise time can flow. Although power MOSFETs are capable of switching high currents for short periods, these short-circuit currents can destroy the component within a few microseconds. Shutdown in the event of a short circuit should therefore occur in the lower microsecond range. A voltage-monitored MOSFET is switched off within a few microseconds if a specific drain-source voltage is exceeded.

[0032] Especially with capacitive loads, and especially with halogen lamps, very high inrush currents occur, which are many times the rated current. Distinguishing between a short circuit and a short circuit is only possible after milliseconds and requires considerable effort. Furthermore, the resistance between the drain and source of the MOSFET in the on state RDS(on) exhibits a very large variation due to manufacturing tolerances and its temperature dependence, which is reflected in a very high variation in the shutdown threshold. A problem with the state of the art is that shutdown in the event of a short circuit and "passing" the inrush current are not possible with current designs.

[0033] To solve such a problem, the approach presented here proposes a current source 120 connected in parallel to the power MOSFET Q4 as switch 140 with the maximum current I1, which precharges the capacitive load for a few milliseconds or heats the tungsten filament of the lamp. The current is limited by the current source 120. In the event of a "true short circuit," only the maximum current set by the current source flows. Destruction of the components of the device 100 is prevented. After a few milliseconds, the actual switching element Q4 switches on as switch 140, and after, for example, a brief overlap phase, the current source 120 is switched off. The entire rated current now flows via switch 140.

[0034] The DC power source 120 can be realized, for example, with the help of a Smart Power MOS. As a result, the inrush current through the power source 120 can be limited to the maximum current I1, and at the same time, in the case of a capacitive load, the capacitance can be charged, or in the case of a halogen lamp, the filament can be heated to such an extent that the rated resistance of the electrical component 105 is set. At the moment of switching on the switch 140, the consumer or the electrical component 105 is already in the rated current range.

[0035] The approach presented here can be implemented in a variety of ways. A first possible solution involves using a switchable current-limiting circuit with bipolar transistors to implement the current source 120. The current is limited to a specific value I1. This limited current I1 charges the capacitive load or heats the lamp wire to its nominal resistance. Even in the event of a short circuit, the current is limited by the maximum current I1. This prevents damage to the components and wiring harness in the vehicle or in the vicinity of the electrical component 105. After a few milliseconds, the power supply can be switched to the output MOSFET as switch 140.

[0036] A second solution is a parallel "SmartFET." The "SmartFET" (also known as a Smart Power MOS) features thermal protection. If an overcurrent or short circuit occurs, the SmartFET shuts itself down via a thermal diagnostic circuit. Due to its thermal inertia, short-term, non-critical current peaks are not diagnosed in the "SmartFET." At the same time, a capacitive load can be precharged or the lamp filament can be heated to its nominal resistance. Short-circuit resistance is thus guaranteed. There are no stringent requirements, as the "SmartFET" is only active at the moment of switch-on. Accordingly, this solution is compact and inexpensive. Furthermore, no cooling bench space is required for the "SmartFET," which is explained by the fact that the SmartFET's short switch-on time allows it to be placed next to the cooling bench.

[0037] With the approach presented here, switching capacitive loads and / or lamps with a voltage-monitored MOSFET in a safety control unit, for example, for hydraulic applications, can be implemented very simply and efficiently. Compliance with safety standards can also be ensured, thus protecting the output itself. Destruction of the MOSFET as a switch is prevented at any time during operation. Incorrect diagnosis due to the high inrush current, which leads to shutdown of the output stage, is also prevented.

[0038] Important aspects and advantages of the invention include the realization of a cost-effective and simple solution for integrating functional expansion for controlling capacitive loads and lamps into an existing power stage concept of an engine or hydraulic control unit. It also allows for easy implementation. The approach presented here can also be used in safety-critical applications, as the short-circuit detection and short-circuit resistance of the power stage are retained. Backward-compatible integration of the circuit into existing software solutions is also possible. No additional space is required on the control unit's cooling bench, as the additional components, for example, do not need to be cooled. Furthermore, the approach presented here offers cost-effective implementation due to the requirement of only standard components. Fig.4 shows a flow diagram of an embodiment of the approach presented here as a method 400 for controlling an electrical component, wherein the method 400 comprises a step 410 of applying a current flow with a predefined maximum current intensity to the electrical component via a current source and the step 420 of closing a switch connected in parallel to the current source in order to supply the electrical component with energy from a power supply connection in order to control the electrical component. The method 400 can also provide an optional step 430 of deactivating the current source after the closing step 420, in particular wherein the deactivation step occurs within a time interval of 1 second after the closing step.

[0039] The embodiments shown are only examples and can be combined with each other. List of reference symbols 100 Device for controlling 105 electrical component 110 Control unit 120 power source I1 maximum current 125 supply connection 130 resistance 135 opening unit 140 switches 200 count 205 Time interval 210 Switch-on time, first time 212 Exceeding the short-circuit threshold 215 Short circuit threshold 220 starting current, current peak 230 second point in time 400 Method for controlling an electrical component 410 Step of Memorization 420 closing steps 430 optional deactivation step

Claims

[1] Method (400) for controlling an electrical component (105), the method (400) comprising the following steps: - impressing (410) a current flow with a predefined maximum current intensity (I1) on the electrical component (105) by a current source (120); and - closing (420) a switch (140) connected in parallel to the power source (120) in order to supply the electrical component (105) with energy from a power supply connection (125) in order to control the electrical component (105). [2] Method (400) according to claim 1, wherein the step (410) of imprinting is carried out within a period of at most one second, in particular of at most 100 milliseconds, preferably of at most 10 milliseconds, before the step (420) of opening. [3] Method (400) according to one of the preceding claims, wherein in the closing step (420) a power semiconductor switch is closed as a switch (140), in particular wherein the power semiconductor switch is designed as a MOSFET, a thyristor or an IGBT. [4] Method (400) according to one of the preceding claims, wherein in the step (410) of impressing a current source (120) is used which comprises a transistor circuit (Q4, Q1, Q5), in particular a bipolar transistor circuit. [5] Method (400) according to one of the preceding claims, wherein in the step (410) of impressing, an electronic component is used as the current source (120) which has a thermal overload protection device, in particular wherein the thermal overload protection device is designed to switch off the electronic component at a maximum electrical power which is less than a nominal transmission line of the switch (140). [6] Method (400) according to claim 5, wherein in the step (410) of impressing a current source (120) is used, the thermal heat dissipation of which is independent of a heat sink of the switch (140) and / or the electrical component (105). [7] Method (400) according to one of the preceding claims, wherein in the closing step (420) an electrical component (105) is supplied with energy from the energy supply connection (125), which is formed by a capacitive load and / or by a lamp, in particular by a halogen lamp and / or an LED lamp. [8] Method (400) according to one of the preceding claims, wherein after the closing step (420) a step (430) of deactivating the power source (120) is provided, in particular wherein the deactivating step (430) takes place within a time interval of 1 second after the closing step. [9] Control unit (110) which is configured to execute and / or control the steps (410, 420) of the method (400) according to one of the preceding claims in corresponding units (115, 135). [10] Computer program configured to execute and / or control the steps (410, 420) of the method (410, 420) according to any one of the preceding claims. [11] A machine-readable storage medium on which the computer program according to claim 10 is stored. [12] Device (100) for controlling an electrical component (105), the device (100) having the following features: - a current source (120) for impressing a current flow with a predefined maximum current intensity (I1) onto the electrical component (105); - a switch (140) connected or switchable in parallel with the power source (120), which is designed to supply the electrical component (105) with energy from a power supply connection (125) in order to control the electrical component (105); and - a control unit (110) according to claim 10.

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