Circuit arrangement and method for detecting a short circuit

Abstract

The invention relates to a circuit arrangement comprising an inverter (2) and a measuring device (3) for identifying a short circuit between a conductor (8) and a shield (9) in a circuit (4) connected or connectable to the inverter (2). The shield (9) is capacitively connected to a ground (GND1) of the inverter (2) and a pulse voltage (U P ) can be generated by the inverter (2) on the conductor (8). The measuring device (3) is designed to evaluate a voltage (U M ) between the ground (GND1) of the inverter (2) and the shield (9) and to generate a short circuit signal upon occurrence of at least one pulse of the voltage (U M ).

Description

Technical Field

[0001] This invention relates to a circuit arrangement including an inverter and a measuring device for identifying short circuits between conductors and shielding in a circuit connected to or potentially connected to the inverter, wherein the shielding capacitor is connected to the inverter's ground, and a pulse voltage can be generated on the inverter's conductors. The invention also relates to a method for detecting short circuits between conductors and shielding in a circuit connected to the circuit arrangement, wherein the circuit arrangement includes an inverter and a measuring device for determining the short circuit. Background Technology

[0002] Strict electromagnetic compatibility (EMC) requirements apply to the circuit layout in motor vehicles to prevent interference with other circuit layouts inside and outside the vehicle. In many cases, such circuit layouts include components such as motors operated by inverters. Short circuits can occur if there is a connection between conductors and shielding in the component or in the connectors used to connect the component.

[0003] Such short circuits can cause the shielding to lose its shielding effect, i.e., its ability to prevent electromagnetic interference emissions, due to the electrical connection between the conductor and the shielding. This results in the circuit layout no longer meeting electromagnetic compatibility or required limits. For example, this can happen with conductors carrying motor phase currents, because when a short circuit occurs, the pulse voltage of the motor phase is applied to the shielding, and the shielding thus significantly loses its shielding effect on the conductor.

[0004] In order to respond to potential interference from shielding, it is desirable to be able to identify or detect the occurrence of such short circuits. Essentially, it is known that short circuits can be detected by measuring the short-circuit current. However, particularly in circuit arrangements used in motor vehicles, there may be system architectures where, due to purely capacitive connections between various potentials, a closed circuit is not formed between the conductors and the shielding for DC or low-frequency AC currents in the event of a short circuit. In this case, the short circuit does not result in a significant short-circuit current or an increase in the current connected to the conductors of the shielding via the short circuit. However, even in this case, the shielding effectiveness of the shielding may be lost, thus it is desirable to be able to identify the occurrence of such short circuits. Summary of the Invention

[0005] Therefore, the present invention aims to describe a circuit arrangement that enables improved determination of short circuits between conductors and shielding in circuits connected to or potentially connected to an inverter, particularly when the short circuit does not result in a significant short-circuit current.

[0006] To achieve this objective, in the circuit arrangement of the type mentioned at the beginning, according to the present invention, a measuring device is provided that is designed to evaluate the voltage between the inverter's ground and shield, and to generate a short-circuit signal when at least one voltage pulse occurs.

[0007] The pulsed voltage generated by the inverter on a conductor can, for example, move current onto the conductor, which is then supplied to a circuit connected to or capable of being connected to the inverter. This circuit can be, for example, a motor or a circuit including a motor. The motor can be directly connected to the inverter and, for example, can be arranged together with the inverter as a common unit in a housing. The circuit with the inverter can also include connection devices, such as single-phase or multi-phase lines or cables, via which the circuit is connected to or capable of being connected to the inverter. In this case, a short circuit between the conductor and the shield may occur in the connection device or between the conductor or conductor potential and the shield or shield potential within another component of the connected circuit or the connected motor.

[0008] Because of the capacitive connection between the inverter's ground and the shield, DC or low-frequency AC power cannot flow back to the energy source via the inverter. If the circuit layout is arranged such that the energy source feeding the inverter is also capacitively connected to the shield or decoupled from the shield's capacitance, then no DC or low-frequency AC power can flow through such a path. In particular, the pulse voltage that the inverter can generate on the conductor has a relatively low frequency, such as 1 kHz or lower, so that the current generated on the conductor cannot flow through the capacitive connection, as this represents high impedance for current.

[0009] Therefore, according to the present invention, a short circuit between the conductor and the shield is determined by measuring the voltage between the inverter's ground and the shield. In the absence of a short circuit, no pulse is generated in the voltage between the inverter's ground and the shield. If a short circuit exists between the conductor and the shield, a pulse voltage will also exist on the shield, and thus a short circuit can be determined by the appearance of a pulse or pulse voltage on the shield or on a conductor connected to the shield potential. Therefore, the occurrence of a short circuit can be detected without requiring a short-circuit current or an increased current to occur on the conductor or the like for short-circuit detection.

[0010] Advantageously, when a short circuit occurs between the conductor and the shield, a short-circuit signal describing the occurrence of the short circuit can be generated. Based on this short-circuit signal, measures can be taken, for example, to account for the short circuit. For instance, in the presence of a short-circuit signal or a short-circuit signal describing that a short circuit has occurred, the inverter and / or the circuits connected to the inverter can be shut down.

[0011] Therefore, it is possible to avoid the circuit arrangement and / or switches that can be connected to or are connected to the circuit arrangement being in an operating state where increased interference emissions occur due to short circuits between conductors and shielding. Thus, it is advantageous to avoid damage to other circuit arrangements near the circuit arrangement due to undetected short circuits. In particular, when this circuit arrangement is used in a motor vehicle, electromagnetic compatibility specifications are met even in the event of a short circuit, and damage due to increased interference emissions from other motor vehicle components and / or other electronic circuits near the motor vehicle can be avoided.

[0012] According to the present invention, a measuring device is provided that generates a short-circuit signal when multiple voltage pulses occur within a predetermined time period. Short-circuit detection and thus short-circuit signal generation only occur when multiple pulses are detected (i.e., the presence of a pulse sequence or pulses and / or periodically changing voltages). A single pulse detected by the measuring device will not result in the generation of a short-circuit signal.

[0013] This has advantages, such as the fact that a single pulse used in a so-called electrostatic discharge (ESD) test will not lead to the detection of a short circuit. Such ESD pulses are particularly prevalent in circuit layouts within motor vehicles, as ESD testing is a common testing method for components installed in or within motor vehicles. Therefore, the measuring device can distinguish between a single, non-repeating voltage pulse that is not caused by a short circuit and is, for example, a result of an ESD test, and whether multiple voltage pulses have been measured, thus suggesting a high probability of a short circuit. The predetermined time for multiple pulses to occur can be selected based on the frequency of the pulse voltage generated by the inverter, and this predetermined time, for example, involves a time range between 1 ms and 1 second, so that subsequent ESD tests will not lead to short circuit detection.

[0014] In a preferred embodiment of the invention, the measuring device may include a comparator, wherein a voltage between the inverter's ground and shield exists at a first input of the comparator, and a reference voltage exists at a second input of the comparator, wherein the measuring device is designed to generate a short-circuit signal from the comparator's output signal.

[0015] The voltage existing between the inverter's ground and the shield can, for example, drop across at least one capacitor connected between the inverter's ground connection and the connection at the potential of the shield, thus causing a capacitive connection or decoupling between the shield and the inverter's ground. The capacitor can be present as an assembly component, particularly on a circuit board carrying the circuit layout. In addition to at least one capacitor, the capacitive connection may also include one or more resistive elements.

[0016] Based on the expected voltage level present across the capacitor or between the inverter's ground and shield, the voltage can be applied directly to the comparator's input or a voltage divider can be used to reduce the voltage, especially when the expected voltage is higher than the comparator's permissible input voltage. Using a comparator that compares the voltage present at the first input with a reference voltage advantageously allows for compensation of voltage fluctuations and / or voltage levels at the first input that cannot be accurately predicted, and always generates the same output signal from the comparator, i.e., logic 0 or 1, regardless of the actual value. Therefore, it is advantageous to assess voltages within a predetermined range that may occur under short-circuit conditions, where the same output signal from the comparator is always generated regardless of the actual level. When generating a short-circuit signal based on the comparator's output signal, a uniform output signal can be used, which occurs when the voltage present at the first input is higher than the comparator's reference voltage. The reference voltage can be generated, for example, in a separate circuit of the measuring device. For example, if there is no current connection between the inverter's ground and the separate ground of the measuring device, an isolated comparator or a comparator with a downstream isolator can be used.

[0017] According to the invention, the measuring device may also include a retriggerable monostable multivibrator, wherein the hold time of the trigger is greater than the period of the pulse voltage generated by the inverter, and the output signal of the comparator is present at the input of the trigger. The measuring device is designed to generate a short-circuit signal when the output signal of the trigger has a constant switching state within a predetermined time period. The retriggerable monostable multivibrator, also called a retriggerable single trigger, changes its switching state from a first switching state or output state to a second switching state or active state within a certain time period by a trigger signal applied to the input of the trigger. Then, after the hold time has elapsed, the trigger returns to its initial state, wherein the retriggerable trigger is restarted by a new trigger signal received during the hold time until the trigger returns to its initial state and remains in the active state. Therefore, the new trigger signal received during the active state and the triggering state prolongs the active state in a timely manner.

[0018] If the inverter can generate different frequencies, for example, to set different speeds in a motor connected to the inverter, then the hold time of the monostable multivibrator is preferably longer than the maximum duration of the pulse voltage generated by the inverter. The hold time can be, for example, twice the duration of the voltage the inverter can generate or the maximum duration. If a short circuit is present, an output signal permanently at the logic value will be generated at the output of the monostable multivibrator because the retrievable trigger is always retriggered by a pulse of the voltage between the inverter's ground and shield, or a pulse of the output voltage arriving during the comparator hold time.

[0019] A short-circuit signal can be generated when the output signal of the monostable multivibrator is at a logic voltage level corresponding to the active switching state for a predetermined time period. This predetermined time period specifically corresponds to a number of pulses of the voltage generated by the inverter. In this way, a simple structure of the measuring device can be implemented using analog components, which generates a short-circuit signal only when a certain number of pulses occur. In particular, when combined with a comparator, tolerance to voltage fluctuations under short-circuit conditions can also be generated, enabling reliable and rapid diagnosis of short circuits.

[0020] According to the present invention, a circuit arrangement may be provided including a control device, wherein a short-circuit signal may be determined by the control device or may be transmitted from a measuring device to the control device, wherein the control device is designed to activate at least one measure when a short-circuit signal is present.

[0021] Therefore, the control device can be part of the measuring device or an additional control device for the circuit arrangement. If it is part of the measuring device, the control device can generate a short-circuit signal based on the output signal of the measuring device, particularly based on the output signal of the trigger. This can be done, for example, when the output signal of the trigger corresponds to the active switching state of the trigger for a predetermined time period. The predetermined time period can particularly correspond to a multiple of the holding period of the trigger and, for example, include the duration of at least ten pulse voltage periods generated by the inverter. Alternatively, the short-circuit signal can be generated by another component of the measuring device based on the output signals of the trigger and / or comparator, wherein the short-circuit signal generated by the measuring device is transmitted to the control device, for example, in the form of a one-bit signal or a voltage corresponding to a predetermined value.

[0022] In addition to identifying or receiving short-circuit signals, the control device may include other functions; specifically, it may control or regulate the inverter. For this purpose, the control device can be connected to or linked to at least one data communication interface, through which it can receive and / or send corresponding information or commands for operating the inverter. If a short-circuit signal is present, the control device can initiate measures that take into account the short circuit. Specifically, the inverter may be shut down and / or short-circuit information describing the presence of a short circuit may be transmitted via the data interface connected to the control device.

[0023] In a preferred embodiment of the invention, the circuit arrangement may include a ground contact and / or a housing, wherein the ground contact and / or housing are at the potential of the shield, and the ground capacitance of the inverter is coupled to the ground contact and / or housing. The ground contact may, for example, be designed as a substrate made of metal, a circuit board of the circuit arrangement, or, in particular, a layer in the structure of a printed circuit board (PCB).

[0024] The grounding potential of the circuit arrangement can also be additionally or alternatively applied to the circuit housing, particularly a metal housing. The potential of the shielding is applied to the grounding contacts and / or the housing. This can be accomplished, for example, via an electrical connection between the grounding contacts and the shielding, particularly via contact pins provided for this purpose. Connection to the housing of the circuit arrangement can also be made, for example, via an electrical pin on the housing, which can be connected to or to the shielding of the circuit.

[0025] According to the invention, an inverter can be provided connected to or may be connected to an energy storage device, wherein the energy storage device is capacitively coupled to a shield. The energy storage device may be, for example, a low-voltage energy storage device, particularly a low-voltage battery providing a voltage of, for example, 12 volts, 24 volts, or 48 volts. Alternatively, the energy storage device may be a high-voltage energy storage device, particularly a high-voltage battery providing a voltage between 400 volts and 800 volts. Capacitive coupling between the energy storage device and the shield can occur directly or indirectly. For example, indirect capacitive coupling may exist if both the energy storage device and the shield are capacitively coupled to another potential (e.g., the chassis of a motor vehicle).

[0026] In the case of circuit arrangements used in motor vehicles, low-voltage energy storage devices can be, for example, batteries designed to supply power to the low-voltage vehicle electrical system. High-voltage energy storage devices can correspondingly be traction energy storage devices that operate the high-voltage on-board electrical system of the motor vehicle and can, for example, supply power to the traction motor via an inverter connected to an inverter circuit. The energy storage device connected to the inverter is also capacitively coupled to a shield or coupled to a chassis coupled to a shield, such that in the event of a short circuit, no short-circuit current can flow into the energy storage device through the conductors and the shield.

[0027] In a preferred embodiment of the invention, the circuit arrangement may include circuitry connected to the inverter, wherein the circuitry includes at least one motor. The inverter of this circuit arrangement may be designed in particular as a three-phase inverter, for example, as a B6 bridge comprising three half-bridges or as a pulse inverter.

[0028] This circuit arrangement can be a roll stabilizer, electric steering system, and / or electric traction drive for a motor vehicle. Many other systems with this architecture are also conceivable, allowing the circuit arrangement to be used for other purposes as well. The electric steering system can be, for example, front-axle steering or rear-axle steering. Therefore, the motor connected to the circuitry of the inverter can be, for example, an electric traction motor for a motor vehicle. The motor in the circuitry can also be part of a motor vehicle actuator other than a traction drive, which is controlled or operated via the circuit arrangement.

[0029] According to the invention, a method for detecting a short circuit between a conductor and a shield in a circuit connected to a circuit arrangement includes an inverter and a shield capacitor connected to the inverter's ground, wherein the inverter generates a pulse voltage on the conductor; the voltage between the inverter's ground and the shield is evaluated, and a short circuit signal is generated when at least one pulse of the voltage occurs.

[0030] If multiple voltage pulses occur within a predetermined time, a short-circuit signal can be generated.

[0031] The circuit arrangement may include a measuring device that evaluates the voltage between the inverter's ground and shield and generates a short-circuit signal when at least one pulse of the voltage occurs. The measuring device may preferably include a comparator, wherein the voltage between the inverter's ground and shield is present at a first input of the comparator, and a reference voltage is present at a second input of the comparator, wherein the short-circuit signal is generated by the measuring device based on the comparator's output signal.

[0032] The measuring device preferably includes a retrievable monostable multivibrator, wherein the hold time of the multivibrator is longer than the period of the pulse voltage generated by the inverter, and the output signal of the comparator is present at the input of the multivibrator. When the output signal of the multivibrator has a constant switching state within a predetermined time period, the measuring device generates a short-circuit signal.

[0033] Preferably, the circuit arrangement may include a control device, wherein a short-circuit signal is identified by the control device or transmitted to the control device by a measuring device, wherein if a short circuit exists, the control device initiates at least one measure.

[0034] All the advantages and configurations described above regarding the circuit arrangement according to the invention are accordingly applicable to the method according to the invention, and vice versa. Attached Figure Description

[0035] The present invention will now be described with reference to the accompanying drawings and exemplary embodiments. The drawings are schematic illustrations, in which:

[0036] Figure 1 An exemplary embodiment of the circuit arrangement according to the present invention is shown, and

[0037] Figure 2 A detailed view of the measuring device with the circuit arrangement according to the present invention is shown. Detailed Implementation

[0038] Figure 1An exemplary embodiment of circuit arrangement 1 is shown. This circuit arrangement includes an inverter 2 and a measuring device 3 for determining short circuits in circuits 4 connected to or accessible to the inverter 2. In this example, circuit 4 connected to the inverter 2 includes a motor 5 and a connection device 6, which in this case is designed as a three-phase shielded motor cable. In this exemplary embodiment, three-phase alternating current can be transmitted from the inverter 2 to the motor 5 via the connection device 6, enabling motor operation of the motor 5 via the inverter 2. To provide this alternating current, the inverter 2 is connected to an energy storage device 7. The inverter 2 can be designed, for example, as a B6 bridge.

[0039] The measuring device 3 is designed to detect short circuits between conductor 8 and shield 9 in circuit 4. This short circuit is schematically shown as a dashed connection 10 between conductor 8 and shield 9. Short circuits may occur in the connecting device 6 or within the motor 5.

[0040] Conductor 8 is connected to the AC side of inverter 2. In this case, shield 9 is connected to the ground potential GND1 of inverter 2 via capacitor C1. Shield 9 is connected to the housing 12 of circuit arrangement 1 via contact pin 11, wherein housing 12 is a metal housing and represents the ground potential GND1 of circuit arrangement 1. Capacitor C2 is arranged between the ground potential GND1 of inverter 2 and the ground terminal GND2 of housing 12, such that the ground potential GND1 of inverter 2 is also coupled to shield 9 connected to housing 12 via capacitor C2.

[0041] In addition to capacitors C1 and C2, the connection between GND1 and GND2 may also include one or more resistive elements. Capacitors C1 and C2, as well as any resistive elements present, may be designed, for example, to form, fully or partially, mounted capacitors or resistors on the printed circuit board of circuit arrangement 1.

[0042] Circuit arrangement 1 is shown in its installation state within a motor vehicle, where the connection of components to the ground potential GND3 of the motor vehicle is also shown, for example, to the ground of the vehicle chassis. Housing 12 is connected to ground GND3 via resistor R1. The ground potential GND4 of motor 5 in circuit 4 is also coupled to ground GND3 via resistor R2. Energy storage 7 is also coupled to ground GND3 via capacitor C3. When short circuit 10 occurs between conductor 8 and shield 9, each possible short-circuit current path flows through at least one of the capacitive connections formed by capacitors C1, C2, and C3. In this way, direct current or low-frequency alternating current cannot flow as a short-circuit current because the capacitive connections used for such currents each represent infinite or at least very high impedance.

[0043] Inverter 2 generates a pulse voltage on conductor 8 of circuit 4, which in this case is a three-phase voltage, for example, with a switching frequency between 1 kHz and 500 kHz, particularly between 10 kHz and 20 kHz. This voltage generates a current on conductor 8 of circuit 4, with a frequency, for example, between 1 Hz and 10 kHz, particularly between 1 Hz and 1 kHz. If a short circuit occurs between conductor 8 and shield 9, a voltage Up from one phase of the pulse generated by the inverter's switching frequency also exists on shield 9, wherein the frequency of voltage Up is significantly higher than the frequency of the current fed into motor 5, also known as the motor current fundamental frequency.

[0044] Because of the voltage Up applied to the shield 9, it loses its shielding effect. This could lead to electromagnetic compatibility (EMC) damage to circuit 4, which is why the measuring device 3 is designed to detect such a short circuit. Since a short circuit cannot be measured by the short-circuit current or by measuring the phase current flowing through conductor 8 to power motor 5, the voltage U between inverter 2's ground GND1 and the shield 9 is... M Evaluated by measuring device 3. Voltage U M This corresponds to the switching frequency of inverter 2, and its frequency is significantly higher than the motor current frequency. The measuring device 3 is also configured to generate a short-circuit signal when at least one pulse of this voltage occurs.

[0045] The housing 12 of the circuit arrangement 11 can be designed as a metal housing connected to the ground potential GND2. Alternatively, the grounding contact of the ground potential GND2 can be designed as a layer of a conductive metal plate and / or a circuit board (e.g., a printed circuit board) of the circuit arrangement 1.

[0046] The structure of measuring device 3 is schematically shown as follows Figure 2 As shown. The measuring device 3 includes a comparator 13 and a trigger 14. Furthermore, the measuring device 3 includes a control device 15, which is designed, for example, as a microcontroller. Alternatively, the measuring device 3 is connected to the control device 15 of the circuit arrangement 1, as will be explained in more detail below. Figure 2 In this circuit, the ground potential of control device 15 is designated as GND5. The ground potential GND5 of control device 15 can be electrically connected to the ground potential GND1 of inverter 2. For this purpose, for example, a current connection 16 in the form of a conductor path can exist on the circuit board of circuit arrangement 1. Alternatively, another type of current connection 16 can be formed, such as metallization of the connection between the equipotential surfaces of one or more circuit boards of circuit arrangement 1 assigned to ground potentials GND1 and GND5. If there is no current connection between the ground potentials GND1 and GND5 of inverter 2, comparator 13 can also be designed as an isolated comparator or a comparator with a downstream isolator.

[0047] The voltage U between the ground potential GND1 of inverter 2 and the ground potential GND5 of control device 15 connected thereto, and the ground potential GND2 of shielding or circuit arrangement 1. M The voltage exists at the first input terminal 17 of comparator 13. Reference voltage source 19 is connected to the second input terminal 18 of the comparator, such that the voltage present at the first connection 17 is equal to the reference voltage U present at the second connection 18. R A comparison can be made. For example, the first connection 17 can be the negative connection of the comparator and the second connection 18 can be the positive connection of the comparator. Reverse distribution is also possible. Depending on the voltage level that may occur between the shield 9 and the ground GND1 of the inverter 2, the measuring device 3 may include a voltage divider, such that the voltage U M It can be reduced to a voltage level that matches the input 18 of comparator 13.

[0048] The output 20 of comparator 13 is connected to flip-flop 14. Flip-flop 14 is designed as a retriggerable monostable multivibrator, also known as a retriggerable single flip-flop, and can be, for example, in the form of an integrated circuit (IC). The hold time of flip-flop 14 is longer than the pulse voltage U generated by inverter 2. p During the period, the pulse voltage U p It is applied to conductor 8 or, in the case of a short circuit, to shield 9. The holding time may be, for example, at least twice the duration of the time period that inverter 2 can generate or the maximum time period duration when circuit 4 or motor 5 is running.

[0049] The use of comparator 13 makes it possible to measure voltage U even when the voltage is being measured. M Exceeding the reference voltage U R Even when there is a different voltage between the ground GND1 of the inverter 2 and the shield 9, a similar output signal corresponding to the logic level can be generated at the output terminal 20 of the comparator 13. In this way, the measuring device 3 can be designed to be robust and adaptable to different high voltages U. M This improves the reliability of measuring device 3 or circuit arrangement 1 in detecting short circuits.

[0050] The use of the monostable trigger 14 allows the measuring device 3 to be designed as follows: when several measuring voltage pulses U M If the short circuit occurs within the predetermined time, the measuring device 3 generates a short circuit signal. If the trigger 14 is designed as a retrievable monostable multivibrator, and the holding time of the active state of the trigger 14 is greater than the pulse voltage U generated by the inverter 2... p During the period when a short circuit occurs, the hold time of flip-flop 14 is continuously retriggered, so that the output terminal 21 of flip-flop 14 gives a constant signal level.

[0051] If this condition persists for a predetermined time, particularly longer than one or more periods of the pulse voltage generated by inverter 2, a short circuit can be determined. The output 21 of trigger 14 can be connected to control device 15, where control device 15 performs a corresponding evaluation of output 21. This means that control device 15 monitors whether trigger 14 has an active switching state for a specified time. Alternatively, another type of evaluation can be performed, for example, by another, particularly analog, component of measuring device 3. In this case, the control device cannot represent a component of the measuring device, where a short-circuit signal generated by measuring device 3 is transmitted to control device 15.

[0052] Both scenarios offer the advantage that the short-circuit signal, whether present in analog form or identified based on the duration of the analog signal at the output 21 of trigger 14, allows for rapid and digitally delay-free initiation of measures due to the short circuit. For example, the short-circuit signal can be transmitted to another component of motor 5 or circuit 4, causing them to stop operating. Another type of use in circuit 4 is also possible, particularly if circuit 4 has a different structure than that shown. Furthermore, control device 15 can be connected to a communication link, allowing short-circuit information and / or information regarding measurements to be performed due to the short circuit to be transmitted to other components of the vehicle.

[0053] Circuit arrangement 1 can be designed, for example, as a roll stabilizer, an electric steering system, and / or an electric traction drive for a motor vehicle. Circuit 4 can represent a portion of circuit arrangement 1, specifically with motor 5 directly connected to inverter 2 without the use of connection device 6. Even in this case, a short circuit between the conductor 8 or line potential inside motor 5 and the shield 9 or shield potential can be detected. Figure 2 As shown, the measuring device 3 and the control device 15 can be designed to be connected to the control unit 22 of the inverter 2. The control unit 22 may also have a device 23 for generating the power supply voltage for the comparator 13 and a device 24 for generating the power supply voltage for the trigger 24. The inverter 2 can also be designed as part of the control unit 22, such as... Figure 1 As shown.

[0054] The energy storage device 7 can be designed as a low-voltage energy storage device, such as a low-voltage battery with voltage levels of 12 volts, 24 volts, or 48 volts. This is especially possible if the circuit arrangement 1 is designed as a roll stabilizer or an electric steering system. In the circuit arrangement 1 designed for an electric traction drive in a motor vehicle, the energy storage device 7 can be designed as a high-voltage energy storage device, particularly a high-voltage battery, and can provide a voltage between 700 volts and 800 volts. Depending on the design of the circuit arrangement 1, the desired size and / or power of the circuit 4, and particularly the motor 5, can also be selected differently. In addition to the above purposes, the circuit arrangement 1 can be used for other purposes.

[0055] In an exemplary embodiment of the method according to the invention, the measuring device 3 evaluates the voltage U between the ground GND1 of the inverter 2 and the shield 9. M And when voltage U M When multiple pulses occur, that is, when a pulse voltage U appears on the shield 9 associated with the ground GND1 of inverter 2. M When this occurs, a short-circuit signal is generated. For this purpose, the voltage U at the first input terminal 17 of comparator 13... M The reference voltage U at the second input terminal 18 of comparator 13 R Compare. If it exceeds the reference voltage U... R This generates an output signal, for example, logic 1, at output terminal 20. For example, this triggers flip-flop 14, causing it to also generate logic 1 at its output terminal 21.

[0056] Because the holding time of trigger 14 is greater than the pulse voltage U of inverter 2 under short-circuit conditions. p The time period is greater than the pulse voltage U between the ground GND1 of inverter 2 and the shield 9. M This enables continuous re-triggering of flip-flop 14. For example, logic 1 may permanently appear at the output terminal 20 of the flip-flop, wherein if the time period during which logic 1 appears is longer than the hold time of flip-flop 14, a short-circuit signal is generated by the control device 15. The hold time of flip-flop 14 may, for example, correspond to U. p The time period is twice the duration of the voltage U, and the time period during which the control device 15 evaluates the signal at the output terminal 21 of the trigger 14 can be the voltage U. p The time period is several times longer, for example, ten times longer, and therefore exceeds the hold time of the trigger.

[0057] If a shorter hold time is selected for the trigger and the control device 15 evaluates a shorter time period for the signal at the output terminal 21 of the trigger 14, then the voltage U M A single pulse can also result in the generation of a short-circuit signal describing a short circuit that has occurred. This can be done, for example, if short-circuit detection does not need to be robust to ESD testing.

[0058] The control device 15 can then take measures to counteract the short circuit that has occurred. For example, the control device 15 can also be designed to control or regulate the inverter 2 and to turn off the inverter 2. Alternatively or additionally, the control device 15 can transmit the corresponding short circuit information via a data interface (not shown here), so that, for example, when circuit 1 is arranged in a motor vehicle, corresponding measures can also be taken by other components of the motor vehicle.

[0059] The use of trigger 14 and several voltage pulses U M The advantage of this detection method is that, for example, a single pulse occurring as part of an ESD test will not be detected as a short circuit between conductor 8 and shield 9. Only a few pulses within a predetermined time period (e.g., between 1 ms and 1 s) are interpreted as short circuits by measuring device 3. This ensures that no short circuits are detected during ESD testing of a motor vehicle including circuit arrangement 1.

[0060] List of reference numerals

[0061] 1. Circuit layout

[0062] 2 Inverter

[0063] 3. Measuring device

[0064] 4. Circuit

[0065] 5 motors

[0066] 6. Connecting device

[0067] 7. Energy Storage

[0068] 8 conductors

[0069] 9 Shielding components

[0070] 10 Connections

[0071] 11 Contact pin

[0072] 12. Shell

[0073] 13 Comparators

[0074] 14 Triggers

[0075] 15. Control device

[0076] 16 Connections

[0077] 17 First Input Terminal

[0078] 18 Second Input Terminal

[0079] 19. Reference Voltage Source

[0080] 20 Output terminal

[0081] 21 Output terminal

[0082] 22 Control Unit

[0083] 23 devices

[0084] 24. Device.

Claims

1. A circuit arrangement comprising an inverter (2) and a measuring device (3), the measuring device (3) being used to identify short circuits between conductors (8) and shielding (9) in a circuit (4) connected to or capable of being connected to the inverter (2), wherein, The shield (9) capacitor is connected to the ground (GND1) of the inverter (2) and can generate a pulse voltage (U) on the conductor (8) by the inverter (2). P The measuring device (3) is designed to evaluate the voltage (U) between the ground (GND1) and the shield (9) of the inverter (2). M ), and when the voltage (U) appears M A short-circuit signal is generated when at least one pulse of ) is received.

2. The circuit arrangement according to claim 1, characterized in that, The measuring device (3) is designed to respond when the voltage (U) appears within a predetermined time. M The short-circuit signal is generated when a number of pulses are applied.

3. The circuit arrangement according to claim 1, characterized in that, The measuring device includes a comparator (13), wherein the voltage (U) between the ground (GND1) of the inverter (2) and the shield (9) is measured. M ) exists at the first input terminal (17) of the comparator (13), and the reference voltage (U) R The short-circuit signal is present at the second input terminal (18) of the comparator (13), wherein the measuring device (3) is designed to generate the short-circuit signal based on the output signal of the comparator (13).

4. The circuit arrangement according to claim 3, characterized in that, The measuring device (3) includes a retrievable monostable multivibrator (14), wherein the hold time of the multivibrator (14) is greater than the pulse voltage (U) generated by the inverter. P The short-circuit signal is generated when the output signal of the comparator (13) is present at the input of the flip-flop (14) during a predetermined time period, and the measuring device (3) is designed to generate the short-circuit signal when the output signal of the flip-flop (14) has a constant switching state during a predetermined time period.

5. The circuit arrangement according to any one of the preceding claims, characterized in that, The circuit arrangement (1) includes a control device (15), wherein the short-circuit signal can be determined by the control device (15) or can be transmitted from the measuring device (3) to the control device (15), wherein the control device (15) is designed to activate at least one measure when the short-circuit signal is present.

6. The circuit arrangement according to any one of claims 1-4, characterized in that, The circuit arrangement includes a ground contact and / or a housing (12), wherein the ground contact and / or the housing (12) are at the potential of the shield (9), and the ground (GND1) capacitor of the inverter (2) is coupled to the ground contact and / or the housing (12).

7. The circuit arrangement according to any one of claims 1-4, characterized in that, The inverter (2) is connected to or can be connected to the energy storage device (7), wherein the energy storage device (7) is capacitively coupled to the shield (9).

8. The circuit arrangement according to any one of claims 1-4, characterized in that, The circuit arrangement has a circuit (4) connected to the inverter (2), wherein the circuit includes at least one motor (5).

9. The circuit arrangement according to claim 8, characterized in that, The circuit arrangement (1) is for a roll stabilizer, electric steering system and / or electric traction drive of a motor vehicle.

10. A method for detecting a short circuit between a conductor (8) and a shield (9) in a circuit (4) connected to a circuit arrangement (1), wherein, The circuit arrangement (1) includes an inverter (2), and the shield (9) is capacitorly connected to the ground (GND1) of the inverter (2), wherein the inverter (2) generates a pulse voltage (U) on the conductor (8). P ), wherein the voltage (U) between the ground (GND1) of the inverter (2) and the shield (9) is M ) was evaluated, and the voltage (U) was observed. M A short-circuit signal is generated when at least one pulse of ) is received.

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