Circuit arrangement for a high-voltage component in a motor vehicle, component and method for operating the component

Abstract

A circuit arrangement (10) for a component operating in a high-voltage range in a motor vehicle, in particular for an electrically operated heater, comprises a low-voltage connection (16) through which an input voltage in a low-voltage range can be provided, a DC-DC converter (40) configured to convert the input voltage applied to its input into an output voltage at its output, a control device (50) connected to the output of the DC-DC converter and configured to control operation of the component in the high-voltage range, a high-voltage connection (20) through which a current can be provided for the operation of the electrical component in the high-voltage range, and an interlock circuit (30) with an interlock loop (32), wherein the interlock circuit (30) is configuredto generate an interlock signal depending on the state of a connector (22) at the high-voltage terminal (20). The interlock circuit (30) is connected to the DC-DC converter (40) so that the DC-DC converter (40) outputs a voltage with a first or second value, depending on the generated interlock signal. Furthermore, the control device (50) is configured to detect the first and second voltage values ​​and, depending on these, output a signal representing the state of the connector (22) at the high-voltage terminal (20).

Description

Technical field

[0001] Several aspects concern a circuit arrangement for a high-voltage component in a motor vehicle, in particular for an electrically operated heating device, in which an HV interlock is implemented as a safety measure to prevent electric shocks or fires. Technical background

[0002] It is common practice to use high-voltage interlocks (HV interlocks) in electrical systems and / or, in particular, in vehicles to protect people and equipment from high voltages. The HV interlock is a safety system that continuously monitors whether all high-voltage components are safely (and correctly) connected. Should an implausible or unexpected connection occur between components—for example, a short circuit due to faulty wiring, damage, or a faulty circuit—the HV interlock interrupts the current flow to prevent the risk of electric shock or fire.

[0003] This technology is particularly important in areas such as electromobility (electric and hybrid vehicles), aerospace, energy generation and distribution, and industrial applications where high voltage is used. The HV interlock helps ensure compliance with safety regulations, thus protecting both operators and technical equipment.

[0004] For example, an HV interlock is used to detect whether an HV connector, which connects an electrical component to the high-voltage supply of a vehicle, is inserted into the corresponding socket of the connector. In this example, the HV interlock essentially functions as a safety circuit that ensures the high-voltage supply is only activated when the connector is fully and correctly inserted and a secure electrical connection has been established.

[0005] The high-voltage interlock can be implemented, for example, using an interlock loop or an electrical signal path. A (low-voltage) test voltage is applied between two terminals of a cable in the component to be connected. The loop extends into the socket, where it is interrupted, thus forming two signal contacts. A corresponding connecting wire is implemented in the plug, forming opposing signal contacts. Inserting the plug (correctly) into the socket closes the loop, similar to a switch, which can be detected. The result can then be transmitted, for example, via the communication interface of a vehicle control unit (e.g., a vehicle control unit, VCU, or a battery management controller, BMC).

[0006] When the plug is inserted into the corresponding socket, the individual contacts can be mechanically spring-loaded and spatially arranged so that they are connected in a specific sequence. Typically, the signal contacts are connected first, followed by the power supply contacts that transmit the high-voltage voltage. This allows the system to, for example, verify that the plug is inserted correctly before the high-voltage voltage is activated.

[0007] As soon as the control electronics receive confirmation via the closed signal path that a secure connection has been established, the high-voltage supply is activated. Without this confirmation, the high-voltage release remains deactivated, and no current flows through the connector for high-voltage operation. Furthermore, continuous monitoring is implemented: during use, the system continuously monitors the status of the interlock signal. Should the connection be interrupted during operation (e.g., by partially unplugging or disconnecting the connector), the high-voltage supply is immediately cut off to minimize safety risks.

[0008] The HV interlock therefore offers a dual protection function: it prevents high-voltage power from being switched on before a secure connection is established, and it deactivates the high-voltage supply if the secure connection is no longer present. This function is particularly important in electric vehicles and other high-voltage applications to provide protection against electric shocks and ensure safety.

[0009] An example of a high-voltage component in a vehicle is an electric vehicle heater. Such a heater might include, for example, a control module with an electronic control unit (ECU), a heating module with several heating elements designed as heating resistors, and a heat exchanger module in which the heat generated by the heating resistors is transferred to a fluid. The heating resistors are powered by the high-voltage current supplied via the HV connector. The electronic control unit, on the other hand, is powered from a low-voltage source. A separate low-voltage connector may be provided for this purpose.

[0010] The electronic control unit handles communication with the vehicle's control electronics and / or other control units via the low-voltage connector, evaluates information received from sensors in the heater, and regulates the operating current through the heating elements, etc. The regulation / control of the heating current can also be achieved via pulse-width modulation using switches or power transistors. To enable this, the microcontroller responsible for this regulation / control can be implemented on the high-voltage side of the electronic control unit. Power is then supplied from the low-voltage side via a DC-DC converter, which converts the input voltage to a galvanically isolated control voltage on the output side. For system safety, the DC-DC converter is of a galvanically isolated type, such as a flyback converter.

[0011] In such a configuration, the high-voltage interlock must be implemented on the low-voltage side – also for system safety reasons. This would generally require a separate microcontroller on the low-voltage side to monitor the test signal in the interlock loop. However, since the control circuitry must be located on the high-voltage side, this means that an additional component – ​​namely, this dedicated microcontroller for the high-voltage interlock – must be implemented. This leads to an increase in components, greater space and energy consumption, additional manufacturing process steps, and thus ultimately higher costs.

[0012] Alternatively, it would also be possible to implement only simple measurement logic on the low-voltage side. This could then, for example via a digital isolator, digitally transmit the result of the interlock signal evaluation (i.e., whether the interlock loop is detected as closed or open) to the microcontroller on the high-voltage side. Alternatively or additionally to a digital isolator, an optocoupler could also be used for analog transmission of the result. However, this approach also has the similar disadvantage that a component bridging the galvanic isolation is required in every case, which entails considerable costs and effort and, in the case of an optocoupler, is also subject to aging effects.

[0013] DE 10 2021 200 414 A1 discloses a vehicle electrical system equipped with a high-voltage branch and a first low-voltage branch, which is galvanically isolated from the high-voltage branch by means of insulation. The low-voltage branch has a low-voltage line, in particular a sensor line, leading to the high-voltage branch. The low-voltage line is a sensor line that leads to a current sensor, a shunt, a temperature sensor, a voltage tap, or another component located within the high-voltage network. The sensor line can be connected to a sensor or a voltage tap of the high-voltage branch or to an interlock terminal of the high-voltage branch for signal transmission. In particular, the sensor line leads to an interlock circuit arranged on a plug component of the high-voltage branch for monitoring purposes.If the monitoring unit in question is located in the low-voltage branch, a corresponding low-voltage line is run from the high-voltage branch to the low-voltage branch to connect the monitoring unit to the interlock circuit. The voltmeter allows monitoring of this low-voltage line as well. Presentation of various aspects

[0014] The task, therefore, is to eliminate the aforementioned disadvantages and problems, save costs and materials, and at the same time ensure the full functionality and safety of an HV interlock.

[0015] Aspects of the invention relate to a circuit arrangement for a component operating in a high-voltage range in a motor vehicle, in particular for an electrically operated heater. The circuit arrangement comprises a low-voltage connection through which an input voltage in a low-voltage range can be provided, e.g., from a low-voltage power source, and a high-voltage connection through which a current can be provided with which a functional part of the component is to be operated; in the example of the heater, this includes one or more heating elements.

[0016] Furthermore, the circuit arrangement also includes a control device configured to control the operation of the component in the high-voltage range. This control device may consist of switches or switching elements, particularly power transistors (IGBTs, power MOSFETs, etc.). In the embodiment of the heating device, these elements can be used, for example, to control the heating power in pulse-width modulated operation of the heating element(s). The control device may be a microcontroller or comprise one or more microcontrollers. The control device may also be part of an electronic control unit (ECU) of the heating device.

[0017] The control device is not powered via the high-voltage connection, but via the low-voltage connection. This means it is activated and ready for operation as soon as the low-voltage connection is properly plugged in or connected, and it can therefore monitor and control the activation of the actual heating operation once its power supply is also signaled and provided via the high-voltage connection.

[0018] However, in order to operate and switch the electronic components, particularly the power switches, which operate at high voltage, the control device itself requires a high-voltage power supply, which must be generated from the low-voltage connection. The circuit arrangement therefore also includes a DC-DC converter, which is configured to convert the input voltage at its low-voltage input into an output voltage at its high-voltage output. According to the foregoing, the control device is connected to the output of the DC-DC converter. The output voltage does not necessarily have to be in the high-voltage range. It can also be significantly lower, e.g., 15 V in a very specific embodiment.However, at least one component of the system operates in the high-voltage range, which is controlled for this purpose by the control device supplied with the output voltage.

[0019] The circuit arrangement also includes a safety system in the form of a high-voltage interlock circuit with an interlock loop that extends, for example, through at least part of a connector of the high-voltage terminal. The interlock circuit is specifically configured to generate an interlock signal depending on the state of the connector and, if necessary, to output it to an internal vehicle communication system. According to one embodiment, the interlock circuit can be specifically configured to generate and, if necessary, output an interlock signal depending on whether the interlock loop is closed by correctly connecting the connector or, conversely, whether it is open.

[0020] The connector, as described earlier, can consist of a plug and a socket. The loop extends on the device side, for example, into the socket, where it is interrupted. Signal contacts may be exposed at the ends of this interruption. Corresponding signal contacts, connected to each other, may be located in the plug. When the plug is correctly inserted into the socket and, for example, locked in place or similarly secured, the signal contacts make contact with each other, thus eliminating the interruption in the interlock loop. Electronically, this configuration acts like a switch in the interlock loop, which is closed when the plug is inserted and opened when it is removed. Other implementations of the switching mechanism than those described are also possible.For example, the plug can have a magnet which, in a defined position of the plug relative to the socket, acts on a spring-loaded conductive spacer in the socket, causing the spacer to move into a position bridging the signal contacts and thus closing the switch. The invention is not limited to specific implementations of the interlock loop and the interlock switch formed therein.

[0021] To ensure that the opening or closing of the interlock switch has a measurable or detectable quality, the interlock loop can be supplied with a low-voltage voltage at one terminal of the interlock switch. On the opposite side of the interlock switch, a change in the applied voltage potential can then be detected when the switch is closed – compared to when it is open. The opening or closing of the switch, depending on the state of the connector, can thus lead to a different voltage potential, which can be tapped and ultimately output at a suitable point in the interlock circuit, depending on the switch state, for example, after further processing. The internal structure of the interlock circuit can be arbitrary within the general scope of this discussion.

[0022] The example above of outputting the interlock signal, depending on whether the interlock loop is closed (by correctly connecting the connector) or open (in the opposite case), can involve outputting a signal when the switch is open and no detectable signal being output when the switch is closed, or vice versa. Two embodiments of this are described below. However, a reverse assignment is equally possible, as is outputting the interlock signal with different detectable values ​​for each case.

[0023] A characteristic feature of the aspects proposed here is that the interlock circuit is connected to the DC-DC converter, so that the DC-DC converter outputs a voltage with a first voltage value or a second voltage value, depending on the output interlock signal.

[0024] Therefore, an existing DC-DC converter is used to transmit an interlock signal from the low-voltage side to the high-voltage side, thus conveying information about the status of the interlock loop. This involves, for example, regulating the voltage of the DC-DC converter so that it outputs a different voltage value at its high-voltage output depending on the state of the connector.

[0025] The control device on the high-voltage side is configured to detect the first and second voltage values ​​and, depending on these, output a signal representing the state of the high-voltage connector. This output can be an internal vehicle communication, e.g., via the vehicle's electrical system (e.g., CAN bus or similar). Alternatively or additionally, this output can also include an internal device response, such as the deactivation or blocking of components. Alternatively or additionally, this output can also include signaling an internal device response to an internal vehicle communication system or outputting data or warning signals via a display device, etc.

[0026] Consequently, according to aspects of the invention, a circuit arrangement of interacting parts can be constructed using the circuit components typically provided in the electrically operated component as such, such as the interlock circuit, the DC-DC converter, and the control device. This arrangement transmits information about a state (state of the connector) from the low-voltage side, via the DC-DC converter, to the high-voltage side without the need to implement additional components such as a low-voltage microcontroller or an optocoupler that overcomes galvanic isolation. This saves costs and effort and reduces the number of parts.

[0027] Aspects of the invention offer the particular advantage that the interlock can be detected from the high-voltage side without the need to implement additional isolation components (for galvanic isolation) or paths. In other words, it is possible to configure the electrically operated component as a single-controller system with only one control device (controller) on the high-voltage side, which can nevertheless provide full interlock functionality without incurring the additional costs that an isolation component such as an additional optocoupler would cause.

[0028] Vehicles within the meaning of this application include, for example, motor vehicles (cars), trucks, construction vehicles, aircraft such as airplanes or helicopters, spacecraft, ships and boats.

[0029] The invention can advantageously be implemented in all components operating in a high-voltage range, particularly in an electrically operated heating device. Electrically operated heating devices are especially suitable as high-voltage applications, as they provide their own ECU for communication and control, which is powered by a low-voltage source and also communicates via the low-voltage connection.

[0030] In exemplary embodiments, low voltage can, for example, denote a range up to a maximum of 12 to 14 V (e.g., terminal 30). However, the low-voltage range can also extend up to 60 V. High voltage denotes, for example, a range from 60 to 1500 V. According to the generalized concept of the invention, these ranges may, in principle, overlap. The ratio between the specific low-voltage and high-voltage voltages is not functionally decisive for the present aspects. An important feature, however, is that the two voltage ranges are galvanically isolated. Functionally, the low-voltage range serves, for example, for signaling, communication, and measurement.In addition to control and regulation tasks, the high-voltage section also serves to operate at least one component of the system in a high-voltage range with a voltage greater than 60V, for example with 250V, 400V or 800V, depending on the high-voltage supply a vehicle can provide.

[0031] According to further training, the DC-DC converter is of the galvanically isolated type. The galvanic isolation provided by such DC-DC converters is a crucial component for system safety. It prevents high voltages from spreading to components that could be touched by people with the risk of injury, or to electronic components that themselves cannot withstand these voltages, in the event of insulation failure and / or short circuits, thus preventing fires or irreparable and costly damage.

[0032] The DC-DC converter can preferably be a flyback converter. However, forward converters, push-pull converters, resonant converters, etc., can also be used as DC-DC converters with galvanic isolation, depending on the design.

[0033] According to one embodiment, the DC-DC converter comprises a low-voltage primary circuit, a high-voltage secondary circuit, a switching regulator which controls a switch in the primary circuit, and a feedback path through which a signal containing information about the current output voltage is fed back to the switching regulator. The DC-DC converter can therefore preferably be a regulated DC-DC converter. In this embodiment, the connection point of the interlock circuit is also connected to the switching regulator via the feedback path in order to vary the feedback signal depending on the interlock signal. In other words, the interlock circuit is configured to intervene in the regulation of the DC-DC converter and thereby influence its output voltage, which in turn can be detected by the high-voltage control device.

[0034] According to a specific advanced design, it is preferred that the feedback path be divided into a low-voltage section and a high-voltage section by means of galvanic isolation. This means that the feedback path, like the converter's storage transformer, bridges the galvanic isolation and / or even incorporates it itself. In this case, the connection point of the interlock circuit is connected to the low-voltage section. Thus, the interlock circuit is located entirely on the low-voltage side. The galvanic isolation with information transmission (interlock: yes or no) to the high-voltage side is therefore completely handled by the DC-DC converter. Since the DC-DC converter is already present, the interlock circuit only needs to be connected to the feedback path without requiring any modifications to the components in the DC-DC converter.

[0035] According to a specific embodiment, the galvanic isolation between the low-voltage path section and the high-voltage path section of the feedback path can be achieved by an optocoupler. It should be noted that this optocoupler would potentially be required for the DC-DC converter anyway. In this case, the invention eliminates the need for a second optocoupler, which would conventionally be required between the interlock circuit and the high-voltage controller.

[0036] Control via feedback of the current output voltage is generally advantageous, as the control system can directly adjust the variable itself. An optocoupler can provide this functionality; however, a disadvantage is that optocouplers are subject to aging effects.

[0037] In an alternative embodiment, the DC-DC converter circuit arrangement (again) comprises a low-voltage primary circuit, a high-voltage secondary circuit, a switching regulator which controls a switch in the primary circuit, and a feedback path. This feedback path now feeds a signal containing information about the current voltage from an additional measuring winding on a storage transformer of the DC-DC converter back to the switching regulator. Here, the feedback in the control loop is therefore indirect, based on parameters that are only related to the output voltage to be set, but do not depend directly on the output voltage Ua. This allows for a slight error in the control, while eliminating the need for an optocoupler, thus reducing costs and the number of components, and improving durability, particularly the lifespan.

[0038] Here too, as in the embodiment above, the connection point of the interlock circuit is connected to the switching regulator via the feedback path in order to detectably influence the feedback signal depending on the interlock signal.

[0039] According to another embodiment, the interlock circuit comprises at least one transistor whose gate or base terminal is connected to the interlock loop (in particular to the interlock switch, which can be implemented by the break and the contacts in the connector), and whose drain or collector terminal, as well as whose source or emitter terminal, in the electrically conductive case, each connect the connection point of the interlock circuit or the feedback path to the ground potential, respectively. This represents a particularly simple implementation of a high-voltage interlock circuit.

[0040] The transistor can be, for example, a MOSFET or a bipolar transistor. The interlock loop allows the transistor to be switched, thereby, for example, pulling the corresponding section of the feedback path to a comparatively lower potential (e.g., transistor conducting when the interlock loop is closed or the connector is correctly plugged in) or leaving it unaffected (transistor blocking when the interlock loop is open or the connector is unplugged).

[0041] In another embodiment, the control device is configured to compare the first and second voltage values ​​with a predetermined reference value or reference interval and, depending on the result, output the signal representing the state of the high-voltage connector. Since slight variations are to be expected when controlling the clocking or duty cycle of the DC-DC converter's switch(es), which are compensated for by the control system, particularly during load changes on the high-voltage side, it may be advantageous to specify a voltage interval for interlock detection within which the measured output voltage should lie, depending on whether the connector is correctly inserted or not.The extent of the influence on the feedback path should therefore be large enough so that these two voltage intervals can be chosen with sufficient distance between them, but possibly also with not too great a distance, so that the control device or the corresponding microcontroller remains operational at both voltage levels.

[0042] According to exemplary embodiments, the first voltage value can correspond to a state in which the plug connection at the high-voltage terminal is correctly established and the operation of the component is activated or to be activated, and the second voltage value can correspond to a state in which the plug connection is not correctly established or not established at all and the intended operation of the component is blocked or to be blocked.

[0043] As described, according to further embodiments, the control device digitally outputs the signal representing the state of the high-voltage connector to a control electronics unit, a battery management system, or another electronic control unit in the vehicle via a vehicle bus. Furthermore, the signal representing the state of the high-voltage connector can include deactivating the high-voltage operation of the electrically driven component via the high-voltage connector, possibly even without external communication.

[0044] Further advantages, features, and details of the various aspects will become apparent from the claims, the following description of preferred embodiments, and the drawings. In the figures, identical reference numerals denote identical features and functions. Brief description of the drawings

[0045] They show: Fig. 1 in a circuit diagram a circuit arrangement according to a first embodiment; Fig. 2 in a circuit diagram a circuit arrangement according to a second embodiment. Preferred embodiment(s) of the invention

[0046] In the following description of preferred embodiments, it should be noted that the present disclosure of the various aspects is not limited to the details of the construction and arrangement of the components as illustrated in the following description and in the figures. The embodiments can be implemented or carried out in practice in various ways. Furthermore, it should be noted that the language and terminology used here are employed solely for the purpose of concrete description and should not be interpreted restrictively by those skilled in the art.Furthermore, in the following description, identical reference numerals in the various embodiments or figures denote identical or similar features or objects, so that in some cases a repeated detailed description of the same is omitted in order to preserve the compactness and clarity of the presentation.

[0047] The Fig. Figure 1 shows a circuit diagram illustrating a circuit arrangement 10 for an electrically operated heating device 1 according to a first embodiment. The circuit arrangement 10 essentially comprises a high-voltage interlock circuit 30, a DC-DC converter 40, and a control device 50, which are described below. It also includes a low-voltage connection 16 and a high-voltage connection 20. However, the high-voltage connection 20 as such merely provides a high-voltage power supply for the operation of heating elements in the heating device, which are not part of the circuit described in Figure 1. Fig. The circuit arrangement considered in section 10 is therefore in Fig. 1. The corresponding high-voltage lines are only schematically indicated. However, connectors are each assigned to the low-voltage connection 16 and the high-voltage connection 20, of which in Fig. Figure 1 shows only the high-voltage connector 22 schematically as a box. Mechanically, the connector 22 is designed as a plug and socket. It is equipped with an HV interlock to meet the safety requirements described above.

[0048] For this purpose, the interlock circuit 30 is provided. The interlock circuit 30 is designed as a module of electronic components that generates a signal, here called the interlock signal, on a low-voltage side LV depending on whether the plug is correctly inserted into the socket of the connector or not, so that a reliable electrical connection in the HV circuit can be ensured, and that this signal is passed on to a high-voltage side HV that is galvanically isolated from the low-voltage side LV. In the specific embodiment of the Fig. The interlock circuit 30 comprises an interlock loop 32 that extends into the connector 22 and is interrupted when the plug is removed or incorrectly inserted, while the connection of the interrupted loop segments is closed when the plug is correctly inserted. The interlock loop 32 is supplied on one side with a low voltage, e.g., 5 V, from a test voltage source Ui, which is generated from the low-voltage connection 16 (not shown). The interruption of the loop segments of the interlock loop 32 and the connection of appropriately configured electrical contacts by a conductive spacer on the plug side acts like a manually actuated electrical switch S1, activated by inserting the plug (which can also be opened again by removing it).

[0049] Opposite the test voltage source Ui with respect to switch S1, the interlock loop 32 is connected to the low-voltage ground potential LV_GND via a high-resistance resistor R1. Between this resistor R1 and the switch S1 formed by the connector, a tap of the interlock loop 32 is connected to a gate of an n-channel MOSFET, forming a second switch S2 in the interlock circuit 30. Depending on the voltage potential applied to the gate, this second switch S2 can open or close a connection between the ground potential LV_GND and a connection point 34 of the interlock circuit 30, with a resistor R2 interposed between connection point 34 and the collector of the n-channel MOSFET. Connection point 34 of the interlock circuit 30 is also a connection point in a feedback path 48 of the regulated DC-DC converter 40.It follows that, depending on the state of the plug connection or connector (correctly plugged in or not), the second switch opens or closes the connection between connection point 34 and the basic potential LV_GND, which has a different effect on the signal level returned in the feedback path 48.

[0050] The DC-DC converter 40 is designed as a flyback converter and comprises a primary circuit 42 with a third switch S3, a secondary circuit 44 with a diode D1 and a storage capacitor C1, the feedback path 48, and a switching regulator 46. The primary circuit is supplied with an input voltage Ue from the low-voltage terminal 16. Intermediate filters, bridges, etc., are not shown. The input voltage Ue can also be reduced or otherwise modified compared to the low-voltage voltage supplied via the low-voltage terminal 16. The flyback converter may also include other components that have been omitted in the simplified representation, in particular a main inductor. The primary circuit 42 and the secondary circuit 44 are connected in a known manner via a storage transformer with windings L1 and L2 around an air-gap core.In the high-frequency switching operation of the third switch S3, which is controlled by the switching regulator 46, the closed third switch S3 charges the storage transformer, while its stored energy is transferred to the secondary side when the third switch S3 is open. The storage transformer provides galvanic isolation 60 between the low-voltage side LV and the high-voltage side HV. The galvanic isolation is symbolically represented by a dashed line. The storage capacitor C1 in the secondary circuit ensures a time-smoothed output voltage Ua at the output 18 of the DC-DC converter, and the diode D1 in the secondary circuit prevents intermediate discharge of the storage capacitor C1. In this configuration, the output voltage Ua is higher than the input voltage Ue, but is not equal to the high-voltage voltage supplied via the high-voltage connection 20.The connector 22 supplies the actual heating power. For example, the output voltage could be 15 V and the high-voltage voltage 250 V.

[0051] A tap for the feedback path 48 is provided at the output 18 of the DC-DC converter 40. The feedback path 48 feeds information about the output voltage Ua from the secondary side 44 back to the primary side 42 and allows the switching regulator 46 to control the operation of the third switch S3 via this feedback in order to maintain a predetermined value for the output voltage Ua. Galvanic isolation 60 is ensured by an optocoupler 49 in the feedback path 48. The optocoupler 49 divides the feedback path 48 into a low-voltage path section 48b and a high-voltage path section 48a. The low-voltage path section 48b connects the optocoupler 49 to an input of the switching regulator 46 via a resistor R4.

[0052] The connection point 34 of the interlock circuit 30 is connected to this low-voltage path section 48b. The low-voltage path section 48b is connected to the low-voltage ground potential LV_GND via a resistor R3. The connection between the connection point 34 of the interlock circuit 30 and the low-voltage ground potential LV_GND, including the resistor R2 provided therein, is arranged in parallel to the connection to the ground potential via resistor R3.

[0053] In other words, if connector 22 is correctly inserted, the second switch S2 is conducting, and the low-voltage path section 48b is connected to the low-voltage ground potential LV_GND via both resistors R2 and R3. If, however, connector 22 is not correctly inserted or not inserted at all, the second switch S2 is blocking, and the low-voltage path section 48b is connected to the low-voltage ground potential LV_GND only via resistor R3. Therefore, in the second case, the switching regulator 46 will detect a higher voltage level at its input than in the first case. Consequently, in the second case, it will operate at a reduced clock rate, resulting in a lower duty cycle, which in turn leads to a lower output voltage Ua at output 18. This is (ua(by selecting the appropriate resistors R2 and R3) so that the control device 50 connected to output 18 is ready for operation even at this output voltage Ua.

[0054] In the first case – with the connector 22 correctly inserted – a load occurs at connection point 34, resulting in a comparatively lower voltage level at the input of the switching regulator 46. Consequently, in the second case, the switching regulator 46 will operate at a higher clock rate or duty cycle, resulting in a higher output voltage Ua at output 18.

[0055] A voltage divider formed by resistors R5 and R6 allows the divided output voltage Ua to be measured via a measuring input UX of the control device and compared with a reference voltage. Depending on the result of this comparison, the control device 50 can therefore determine whether switch S1 is closed or not, i.e., whether connector 22 is correctly plugged in or not. Based on this result, the control device 50 can signal to a control electronics unit, a BMC, or another ECU that the heating device (component) is ready for use or that a problem exists. Furthermore, depending on the interlock signal, the control device 50 can internally activate or deactivate components or circuit sections.

[0056] The Fig. Figure 2 shows a minor modification of the embodiment shown in a second embodiment. Fig. 1. First embodiment shown. Only the differences from the first embodiment are considered. In particular, the function and structure of the interlock circuit 30, the DC voltage converter 40 (flyback converter) and the control device 50 are more or less identical to the first embodiment.

[0057] Unlike the first embodiment, in this DC-DC converter, in addition to a first winding L1 in the low-voltage primary circuit 42 and a second winding L2 in the high-voltage secondary circuit, an additional measuring winding L3 is wound on the storage transformer of the DC-DC converter 40. During operation of the flyback converter, a smoothing capacitor C2, connected to the measuring winding L3 via a feedback path 48 and connected between the feedback path and the low-voltage ground potential LV_GND, charges up. In a manner analogous to how energy is transferred from the storage transformer to the secondary circuit in the flyback converter operation described above, this also occurs – albeit to a much lesser extent – ​​in the feedback path 48.

[0058] Similar to the first embodiment, the feedback path 48 is connected to a terminal of the switching regulator 46. The voltage level on the feedback path 48, smoothed by the smoothing capacitor C2, is a value that is representative of the output voltage Ua achieved in the secondary circuit. Consequently, the switching regulator 46 can regulate the output voltage based on the corresponding feedback from the measuring winding L3.

[0059] The interlock circuit 30 now accesses this feedback path 48 via connection point 34 in the same way as in the first embodiment. The voltage level established on the feedback path 48 during operation of the flyback converter now depends on whether the feedback path 48 is connected to the low-voltage ground potential LV_GND solely via resistor R3 or additionally via resistor R2 of the interlock circuit 30. This is because, as described above, switch S2 establishes the corresponding parallel connection to the low-voltage ground potential LV_GND due to the correctly inserted connector 22. The resulting different output voltages Ua on the secondary side are then detected by the control device 50 as described above.The information and details provided in the specific embodiments are not to be interpreted restrictively with regard to the scope of protection defined in the appended claims. Further modifications are therefore possible. For example, by appropriately selecting and arranging the transistor for the second switch S2, the enabling (closing) of the connection between the feedback path 48 and the low-voltage ground potential LV_GND can also occur in the opposite way, namely in a state of the connector where a correct connection is not established. In this case of an incorrect connection, the output voltage Ua would then be higher compared to the voltage that would be present in the case of a correct connection. Thus, only the distinguishability of the two output voltage values ​​is relevant.

[0060] Alternative arrangements of the interlock circuit 30, even without transistors for the second switch S2, are also possible, for example the use of a reference diode, or the connection between the feedback path 48 or the connection point 34 and the low-voltage ground potential LV_GND is made directly through the interlock loop 32, so that the first switch S1 formed by the contacts in the plug and socket of the connector 22 itself directly influences the voltage level at the connection point 34.

[0061] In a corresponding embodiment, the Fig. 1 or Fig. 2. The second switch S2 and its ground reference, for example, are omitted. Instead of the test voltage supply Ui (or the supply of the interlock signal on line 32), the ground potential can be connected there. Then, closing the first switch S1 (interlock switch) with the interlock correctly connected causes connection point 34 (HV interlock circuit) to be pulled to ground via resistor R2. This could result in a relatively harsh switching of the inherently sensitive feedback signal of the DC-DC converter via the mechanical interlock connector; however, the comparatively high resistance of resistor R2 limits any potential interference. In this embodiment, the first and second switches thus function as one.

[0062] In an alternative embodiment, the second switch can be represented by a reference diode instead of a bipolar or MOSFET transistor, such as the TL431 offered by Texas Instruments. This is a diode with an adjustable reference voltage. The anode of this reference diode is in Fig. 1 or Fig. In this case, point 2 is connected to the low-voltage ground potential LV-GND, the cathode to the ohmic resistor R2, and the reference input to the interlock switch S1. As soon as a certain voltage is applied to the corresponding reference input of the reference diode (acting as the second switch S2), the diode switches the cathode to ground. In this case, the reference voltage would then be set to Ui, which is present when the interlock switch S1 is correctly closed. Consequently, via the reference diode, connection point 34 (HV interlock circuit) is pulled to ground potential LV-GND through resistor R2.

[0063] Further modifications concern other types of DC-DC converters that allow for galvanic isolation. REFERENCE MARK LIST: 1 Electrically operated heater 10 Circuit arrangement 16 Low-voltage connection 18 Output of the DC-DC converter 20 high-voltage connection 22 Connector (high-voltage connection) 24 HV lines (power supply for HV load via HV connectors) 30 (HV) interlock circuit 32 (HV) interlock loop 34 Connection point (HV interlock circuit) 40 DC / DC converters, flyback converters 42 Primary circuit 44 Secondary circuit 46 switching regulators 48 Feedback path 48a High-voltage path section 48b Low-voltage path section 49 Optocouplers of the DC-DC converter 50 Control device (HV microcontroller) 60 Galvanic separation C1 storage capacitor C2 smoothing capacitor D1 diode in the secondary circuit D2 diode in the feedback path HV high-voltage side LV low-voltage side L1-L3 Coils / windings of the storage transformer R1-R6 resistors S1 Interlock switch in the connector S2 switch in the interlock circuit S3 switch in the DC-DC converter Ua Output voltage of the DC-DC converter (HV) Ue Input voltage of the DC-DC converter (LV) Test voltage / test voltage source UX measuring input (measuring HV output voltage)

Claims

Circuit arrangement (10) for an electrical component operated in a high-voltage range in a motor vehicle, in particular for an electrically operated heater, comprising: a low-voltage connection (16) through which an input voltage in a low-voltage range can be provided; a DC-DC converter (40) which is configured to convert the input voltage applied to its input into an output voltage at its output; a control device (50) which is connected to the output of the DC-DC converter and is configured to control operation of the component in the high-voltage range; a high-voltage connection (20) through which a current can be provided for the operation of the electrical component in the high-voltage range;an interlock circuit (30) with an interlock loop (32), wherein the interlock circuit (30) is configured to generate an interlock signal depending on the state of a connector (22) at the high-voltage terminal (20); characterized in that the interlock circuit (30) is connected to the DC-DC converter (40) such that the DC-DC converter (40) outputs an output voltage (Ua) with a first voltage value or a second voltage value at its output, depending on the generated interlock signal; and the control device (50) is configured to detect the first and second voltage values ​​and, depending on these, to output a signal representing the state of the connector (22) at the high-voltage terminal (20). Circuit arrangement (10) according to claim 1, wherein the input and output of the DC voltage converter (40) are galvanically isolated. Circuit arrangement (10) according to claim 1 or 2, wherein the DC voltage converter (40) is a flyback converter. Circuit arrangement (10) according to one of claims 2 or 3, wherein the DC-DC converter (40) has a low-voltage primary circuit (42), a high-voltage secondary circuit (44), a switching regulator (46) which controls a switch (S3) in the primary circuit (42), and a feedback path (48) via which a signal with information about a current output voltage (Ua) is fed back to the switching regulator (46), and a connection point (34) of the interlock circuit (30) at which the interlock signal can be generated is connected to the switching regulator (46) via the feedback path (48) in order to vary the feedback signal depending on the interlock signal. Circuit arrangement (10) according to claim 4, wherein the feedback path (48) is divided by a galvanic isolation (60) into a low-voltage path section (48b) and a high-voltage path section (48a), and the connection point (34) of the interlock circuit (30) is connected to the low-voltage path section (48b). Circuit arrangement (10) according to claim 5, wherein the galvanic isolation (60) between the low-voltage path section (48b) and the high-voltage path section (48a) of the feedback path (48) is effected by an optocoupler (49). Circuit arrangement (10) according to one of claims 2 or 3, wherein the DC-DC converter (40) has a low-voltage primary circuit (42), a high-voltage secondary circuit (44), a switching regulator (46) which controls a switch (S3) in the primary circuit (42), and a feedback path (48) via which a signal with information about a current voltage of an additional measuring winding (L3) on a transformer (L1, L2) of the DC-DC converter (40) is fed back to the switching regulator (46), and a connection point (34) of the interlock circuit (30) at which the interlock signal can be generated is connected to the switching regulator (46) via the feedback path (48) in order to vary the feedback signal depending on the interlock signal. Circuit arrangement (10) according to one of claims 4 to 7, wherein the interlock circuit has at least one transistor (S2) whose gate or base terminal is connected to the interlock loop, and whose drain or collector terminal and whose source or emitter terminal, in the electrically conductive case, each connect to the connection point (34) of the interlock circuit and thus the feedback path to the ground potential. Circuit arrangement (10) according to one of claims 1 to 8, wherein the control device (50) is configured to compare the first and second voltage values ​​with a predetermined reference value or with a predetermined reference interval and, depending on the result, to output the signal representing the state of the plug connection (22) of the high-voltage connection (20). Circuit arrangement (10) according to claim 9, wherein the control device (50) outputs the signal representing the state of the plug connection (22) of the high-voltage connection (20) to a control electronics, a battery management system or another electronic control unit in the vehicle, in particular digitally, via a vehicle bus. Circuit arrangement (10) according to one of claims 1 to 10, wherein the first voltage value corresponds to a state in which the plug connection (22) at the high-voltage terminal (20) is correctly established and the operation of the component in the high-voltage range is activated or is to be activated; and the second voltage value corresponds to a state in which the plug connection (22) is not correctly established or not established at all and the operation of the component in the high-voltage range is blocked or is to be blocked. Component comprising at least one component designed for operation in a high-voltage range, comprising the circuit arrangement according to any one of claims 1 to 11, wherein the at least one component is preferably a heating element. Method for operating a component in the high-voltage range, comprising: providing an input voltage in a low-voltage range at a low-voltage terminal (16); applying the input voltage to an input of a DC-DC converter (40); converting the input voltage into an output voltage at an output of the DC-DC converter (40); controlling operation of the component in the high-voltage range by means of a control device (50) connected to the output of the DC-DC converter; providing current for the operation of the electrical component in the high-voltage range through a high-voltage terminal (20); generating an interlock signal by means of an interlock circuit (30) with an interlock loop (32) depending on a state of a connector (22) at the high-voltage terminal (20);characterized by outputting an output voltage (Ua) with a first voltage value or a second voltage value at a connection point (34) of the interlock circuit (30) with the DC-DC converter (40) depending on the generated interlock signal; and detecting the first and the second voltage value by the control device (50) and, depending on this, outputting a signal representing the state of the plug connection (22) at the high-voltage terminal (20).

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