CN113383493A

CN113383493A - Circuit arrangement for transmitting control signals, power converter and vehicle

Info

Publication number: CN113383493A
Application number: CN201980090604.0A
Authority: CN
Inventors: R.埃德尔豪泽
Original assignee: Valeo Siemens eAutomotive Germany GmbH
Current assignee: Valeo eAutomotive Germany GmbH
Priority date: 2018-12-17
Filing date: 2019-12-03
Publication date: 2021-09-10
Also published as: WO2020126464A1; EP3900184A1; DE102018132496A1

Abstract

A circuit arrangement (1) for transmitting a control signal (3) to a functional element (18), comprising: -first and second supply lines (15, 16) for first and second potentials, -a switching line (17) alternately connected to the supply lines (15, 16), wherein the functional element (18) has a capacitance (20) between the control input (19) and the switching line (17), and the circuit arrangement (1) is configured to: -in the presence of a first signal state of the control signal (3), when the switching line (17) is at a second potential, charging the capacitor (20) to a first target voltage via a first power supply line (15) by means of a charging current, and limiting the discharge current when the switching line (17) is at the first potential to keep the voltage drop across the capacitance (20) outside a voltage interval defined by a first voltage threshold and a second voltage threshold for the function of the functional element (18), and-in the presence of a second signal state of the control signal (3), when the switching line (17) is at a first potential, the capacitor (20) is charged to a second target supplementary voltage via the second power supply line (16) by means of a charging current, and limiting the discharge current when the switching line (17) is at the second potential to keep the voltage outside the voltage interval.

Description

Circuit arrangement for transmitting control signals, power converter and vehicle

Technical Field

The invention relates to a circuit arrangement for transmitting control signals from an input of the circuit arrangement to a functional element of the circuit arrangement, comprising a first power supply line for a first potential, a second power supply line for a second potential different from the first potential, a switching line which can be alternately connected to the first power supply line and the second power supply line, wherein the functional element has a control input and a capacitance between the control input and the switching line.

The invention also relates to a power converter and a vehicle.

Background

For example, such a circuit arrangement is known in gate drivers for power converters, wherein the gates of the power semiconductor switching elements of the power converter are connected to the switching lines of the circuit arrangement. In order to make possible different switching speeds of the power semiconductor switching elements, the series circuit consists of a functional element (in the form of a MOSFET with a gate-source capacitance) and a further resistor which is connected in parallel with the gate series resistor in the switching line. When the functional element is activated in accordance with the control signal, the gate series resistance and the further resistance result in a lower total resistance, which increases the switching speed of the power semiconductor switching element compared to the deactivated switching state of the functional element (in which only the gate series resistance is active).

Since the switching line is alternately connected to the first potential and the second potential and the source terminal of the MOSFET or the functional element is also connected to said alternating potential, an additional voltage source is usually provided which provides the following switching voltages: the two potentials for activating and deactivating the functional element independently of the potential of the switching line at the control input are sufficiently high and are switched to the control input in dependence on the control signal. However, the additional voltage source leads to a higher degree of circuit and component complexity in such a circuit arrangement.

Disclosure of Invention

It is therefore an object of the invention to specify a less complex option for controlling a functional element on a switching line with a varying potential.

According to the invention, this object is achieved by a circuit arrangement of the type mentioned above, which is configured to:

-in the presence of a first signal state of the control signal, charging the capacitance to a target voltage via the first supply line by means of a charging current when the switching line is at the second potential, and limiting a discharging current flowing from the capacitance to one of the supply lines, opposite to the charging current, when the switching line is at the first potential, to keep a voltage drop across the capacitance exceeding a first threshold outside a voltage interval for the function of the functional element defined by the first voltage threshold and the second voltage threshold, and

in the presence of a second signal state of the control signal, the capacitor is charged via the second supply line by means of a charging current to a target voltage that complements the target voltage in the first signal state when the switching line is at the first potential, and a discharging current flowing from the capacitor to one of the supply lines, opposite to the charging current, is limited when the switching line is at the second potential, to keep the voltage drop across the capacitor outside the voltage interval exceeding the second threshold value.

The invention is based on the idea of always charging the capacitor to one of the target voltages in accordance with the signal state of the control signal when the switching line is at one of the two potentials suitable for reaching the target voltage. This occurs via the first power supply line at the first potential when the switching line is at the second potential in the presence of the first signal state, and via the second power supply line at the second potential when the switching line is at the first potential in the presence of the second signal state. If the switching line is at another respective potential, there is at least a limitation of the discharge current, so that the voltage drop across the capacitor does not enter the voltage interval. The capacitor can thus reach the corresponding target voltage in order to provide a voltage at the control input of the functional element which can clearly follow the signal state at the input, regardless of which power line is connected to the switching line.

In this way, the control signal on the input side is advantageously transmitted to the functional element without an additional voltage source having to be provided. This reduces the circuit and component complexity of the circuit arrangement and reduces its production cost compared to conventional circuit arrangements.

The first potential is typically higher than the second potential. The switching line can be or be connected to a driver unit for switching the power supply line to the switching line. The functional element can be configured to perform a function in accordance with a voltage drop across the capacitance or between the control input and the switching line. The function of the functional element may be a switching function, i.e. switching the functional element on and off. The first voltage threshold is typically higher than the second voltage threshold.

The circuit arrangement according to the invention is particularly preferably designed to suppress the discharge current when the respective signal state is applied. Thus, a particularly stable voltage across the capacitor is achieved when the respective signal state is present. As a result, the target voltage can be provided in a particularly stable or "clean" manner at the control input of the functional element. As a result, the voltage across the capacitor can be maintained for a longer time, which is particularly advantageous when switching operating states in which no potential change occurs for a longer period of time (e.g. a few seconds), and therefore the capacitor is not recharged for a longer period of time. Furthermore, this enables the use of simple transistors as functional elements, which are not specifically designed to only generate a voltage swing at their control input with restrictions, and are therefore inexpensive. In this way, the component complexity and cost of the circuit arrangement may advantageously be further reduced.

As will be described in more detail below, the circuit arrangement according to the invention can have one or more switching devices. The switching device or the corresponding switching device can have a control terminal and a switching path between a first terminal and a second terminal of the switching device. The switching path can generally be controlled in dependence on the voltage difference between the control terminal and the second terminal. The switching device is formed, for example, by a transistor connected to a suitable resistance. Typically, in this case, the first terminal of the switching device is connected to a collector or drain terminal of the transistor and/or the second terminal of the switching device is connected to an emitter or source terminal and/or the control terminal of the switching device is connected to a base or gate terminal of the transistor.

The circuit arrangement according to the invention can have a switching device which can be controlled in dependence on a control signal, is connected between the first power supply line and the control input, and is configured to be conductive when the switching line is at the second potential in the presence of the first signal state. This switching device (also referred to as first switching device) is thus able to provide a charging current from the first power supply line to the switching line.

According to a particularly preferred first embodiment of the switching device with the first switching device according to the invention, it is configured to block for the entire duration of the presence of the second signal state. Thus, the first switching device is able to suppress the discharge current when the second signal state is present. For this purpose, the second terminal of the first switching device is preferably connected to a first power supply line.

The circuit arrangement according to the invention can also have a switching device which can be controlled in dependence on a control signal, which is connected between the control input and the second power supply line, and which is configured to be switched on when the switching line is at the first potential in the presence of the second signal state. This switching device (also referred to as second switching device) is thus able to provide a charging current from the second power supply line to the switching line.

In this case, in particular in a particularly preferred first embodiment, it is advantageous if the second switching device is configured to block for the entire duration of the presence of the first signal state. Thus, the second switching device is able to suppress the discharge current when the first signal state is present. For this purpose, the second terminal of the second switching device is preferably connected to a second power supply line. The transistors of the first switching device and the second switching device are preferably of different types, that is to say, for example, npn or pnp bipolar transistors, or alternatively, n-channel or p-channel field effect transistors.

According to a second embodiment of the switching device according to the invention with one or both switching devices, the switching device or the respective switching device can additionally be controlled depending on the potential at the control input of the functional element. In this case, the first terminal of the switching device or of the respective switching device is usually connected to a power supply line. The second embodiment reduces circuit complexity compared to the first embodiment, although the first switching device causes a lower discharge current when the second signal state is present and the second switching device causes a lower discharge current when the first signal state is present. This results in a slightly unstable voltage on the capacitor outside the voltage interval compared to the first embodiment, which may, however, be tolerable, depending on the intended use of the circuit arrangement or the design of the functional element.

It is also useful if a respective diode is connected between the respective switching device and the control input, wherein the diodes have opposite forward directions. In particular, in the first embodiment, these are used to suppress the discharge current.

It is preferred here that resistors are connected in series with the respective diodes, wherein the resistors have different resistance values. In the second embodiment, the current flowing to the corresponding power supply line can be set differently by selecting the resistance value. On the other hand, in the first embodiment, the resistor is mainly used to set the time constant for charging the capacitor.

In the circuit arrangement according to the invention, provision can also be made for the circuit arrangement to have one or two switching elements on the input side, wherein both switching elements or the respective switching element are connected to the supply line via a resistor. In particular, both switching elements or the control terminals of the respective switching elements can form an input. In particular with regard to the first and second embodiments, it can be provided that the control terminals of both switching elements or of the respective switching element are connected between both switching elements or of the respective switching element and the resistor.

According to a third embodiment of the circuit arrangement according to the invention, the circuit arrangement has a resistance unit which connects the switching element and the control input to each other. In particular, the third embodiment operates without a switching device and is therefore particularly easy to implement. However, the third embodiment also has lower voltage stability than the first embodiment, as with the second embodiment.

In this case, it is particularly preferred that the resistance value of the resistance unit depends on the direction of the current flowing through the resistance unit. In this case, the current flowing through the respective power supply line can also be set differently by selecting the resistance value.

In the circuit arrangement according to the invention, the functional element is preferably an electronically controlled switching tube (switch), in particular a field effect transistor. This capacitance is then realized by the gate-source capacitance of the field effect transistor.

The circuit arrangement can also have a resistor in the switching line, wherein the electronically controlled switching tube is connected in series with a further resistor, in order to connect the two resistors in parallel in dependence on the control signal. As a result of the circuit arrangement, the total resistance in the switching line can thus be changed in dependence on the control signal, even if the potential on the switching line varies.

In the circuit arrangement according to the invention, it is also expediently provided that the circuit arrangement has a capacitor connected in parallel with the capacitance. Therefore, the capacitance of the capacitor is added to the capacitance of the functional element.

Furthermore, the circuit arrangement can comprise a voltage limiting unit connected in parallel with the capacitance of the functional element, in particular formed by two zener diodes connected in series in opposite directions. The target voltage can thus be adapted to the maximum voltage and/or the minimum voltage allowed at the control input of the functional unit.

Furthermore, the invention relates to a power converter comprising at least two half-bridges, wherein each of the at least two half-bridges has two series-connected power switching elements, a circuit arrangement according to the invention, a control terminal configured to actuate one of the power switching elements via a switching line, and a voltage supply unit configured for jointly supplying power to the driver unit and the circuit arrangement via a first power supply line and a second power supply line

Finally, the invention relates to a vehicle, in particular a hybrid or electric vehicle, comprising an electric motor configured to drive the vehicle and a power converter according to the invention for supplying power to the electric motor.

All statements relating to the circuit arrangement according to the invention can be applied analogously to the power converter according to the invention and to the vehicle according to the invention, so that the advantages described above can also be achieved with these.

Drawings

Further advantages and details of the invention emerge from the exemplary embodiments described below on the basis of the figures. The following are schematic and are shown:

fig. 1 shows a circuit diagram of a first exemplary embodiment of a circuit arrangement according to the present invention;

FIG. 2 shows a graph of voltage waveforms versus time during operation of the circuit arrangement shown in FIG. 1;

fig. 3 shows a circuit diagram of a second exemplary embodiment of a circuit arrangement according to the present invention;

FIG. 4 shows a graph of voltage waveforms versus time during operation of the circuit arrangement shown in FIG. 3;

fig. 5 shows a circuit diagram of a third exemplary embodiment of a circuit arrangement according to the present invention; and

fig. 6 shows a basic schematic diagram of an exemplary embodiment of a vehicle according to the present invention with an exemplary embodiment of a power converter according to the present invention.

Detailed Description

Fig. 1 is a circuit diagram of a first exemplary embodiment of a circuit arrangement 1, which receives a control signal 3 via an input 2. The circuit arrangement 1 is exemplarily connected to the voltage supply unit 2a via further input terminals 4, 5, to the driver unit 6a via an input terminal 6, and to a control terminal 8 of a power switching element 9 in the form of an Insulated Gate Bipolar Transistor (IGBT) via an output terminal 7.

The voltage supply unit 2a has a first voltage source 10 which provides a voltage for switching the power switching element 9 on, for example +15 volts compared to the potential 11, the potential 11 corresponding to the potential at the reference terminal 8a of the power switching element 9 (here the emitter terminal), and the voltage supply unit 2a has a second voltage source 12 which provides a voltage for switching the power switching element 9 off, for example-8 volts. The driver unit 6a is further connected to the

voltage sources

10, 12 and is configured to alternately provide the voltage of the first voltage source 10 or the voltage of the second voltage source 12 at the input 6 of the circuit arrangement in accordance with a clock signal 14.

The circuit arrangement 1 comprises a first supply line 15 for a first potential, which is supplied by the first voltage source 10 via the input terminal 4, and a second supply line 16 for a second potential, which is supplied by the second voltage source 12 via the input terminal 5. Furthermore, the circuit arrangement 1 comprises a switching line 17, which can be alternately connected to the first power line 15 and the second power line 16, which in the present case is realized by the driver unit 6 a. Therefore, the switching line 17 has a potential that varies with respect to the potential 11 or the

power supply lines

15, 16 in accordance with the clock signal 14.

Furthermore, the circuit arrangement 1 comprises a functional element 18 with a control input 19 and a capacitance 20 between the control input 19 and the switching line 17. The functional element 18 performs a function according to the voltage drop across the capacitance 20. In order to make these functions dependent on the signal state of the control signal 3, the signal state of the control signal 3 is transmitted from the input 2 to the functional element 18. In this case, the first function is performed when the voltage is safely above the first threshold and the second function is performed when the voltage is safely below the second threshold. Thus, the threshold defines a voltage interval within which the capacitance 20 should not be assumed regardless of the potential connected to the switching line 17 and the signal state of the control signal 3, except for the intersection when changing between functions.

In the present exemplary embodiment, the functional element 18 is designed as an electrical switching tube 21 in the form of a field effect transistor and serves to connect a resistor 22 connected in the switching line 17 in parallel with a further resistor 23 depending on the control signal 3, wherein the further resistor 23 is connected in series with the functional element 18, in order thus to provide a gate resistor having a value which is lower than the value of the resistor 22 for switching off the power switching element 9.

For transmitting the control signal 3 to the functional element 18, the circuit arrangement 1 is configured to charge the capacitance 20 to a first target voltage via the first power supply line 15 by means of the charging circuit in the presence of a first signal state of the control signal 3 when the switching line 17 is at the second potential. In this case, when the switching line 17 is at the first potential, the circuit arrangement 1 suppresses a discharge current flowing from the capacitance 20 to the first power supply line 15, which is in the opposite direction to the charging current, to keep the voltage drop across the capacitance 20 beyond the first threshold outside the voltage interval. Similarly to this, the circuit arrangement 1 is further configured to charge the capacitance 20 via the second power supply line 16 to a second target voltage, which complements the first target voltage, by means of a charging current in the presence of a second signal state of the control signal 3 when the switching line 17 is at the first potential. In this case, when the switching line 17 is at the second potential, the circuit arrangement 1 suppresses a discharge current flowing from the capacitance 20 to the second power supply line 16, which is in the opposite direction to the charging current, to keep the voltage drop across the capacitance 20 beyond the second threshold outside the voltage interval. That is, regardless of which of the

power supply lines

15, 16 is currently connected to the switching line 17, the circuit arrangement 1 reverses the charging of the capacitor 20 when the signal state changes to such a high voltage that the control input 19 of the functional element 18 is always at a high potential relative to the switching line 17 in the first signal state and is always at a low potential relative to the switching line 17 in the second signal state.

For this purpose, the circuit arrangement 1 has a first switching device 24 which can be controlled as a function of the control signal 3 and is connected between the first supply line 15 and the control input 19. The first switching device 24 is configured to be conductive in the presence of the first signal state to enable a charging current to flow from the first power line 15 to the capacitor 20. Meanwhile, the first switching device 24 is configured to block when the second signal state is present.

Analogously thereto, the circuit arrangement 1 has a second switching device 25 which can be controlled as a function of the control signal 3 and is connected between the control input 19 and the second power supply line 17. The second switching device 25 is configured to be conductive when the first signal state is present to enable a charging current to flow from the capacitor 20 to the second power supply line 17. Meanwhile, the second switching device 25 is configured to block when the first signal state is present.

Both switching

devices

24, 25 comprise a transistor 26 and a resistor network 27, which sets the operating point of the transistor 26. Transistor 26 thus implements a switching path between first terminal 28 and second terminal 29 of

respective switching devices

24, 25. Thus, the switching path may be controlled in dependence on the voltage difference between the control terminal 30 and the second terminal 29. Since the second terminal 29 of the first switching device 24 is connected to the high potential of the first power supply line 15, the transistor 26 is a pnp bipolar transistor, or alternatively a p-channel field effect transistor. Similarly, since the second terminal 29 of the second switching device 25 is at a low potential of the second power supply line 16, the transistor 26 of the second switching device 25 is an npn bipolar transistor, or alternatively an n-channel field effect transistor.

Furthermore, the circuit arrangement 1 has a first switching element 31 and a second switching element 32, each implementing a switching path between the first terminal 33 and the second terminal 34, wherein the switching paths can be controlled in dependence on a voltage applied to the control terminal 35. The switching

elements

31, 32 also have a transistor 36. In this case, the control terminal 35 is directly connected to the input terminal 2. Whereas the second terminals 34 of the switching

elements

31, 32 are connected to the second power supply line 16, the first terminal 33 of the first switching element 31 is connected to the first power supply line 15 via a resistor 34, and the first terminal 33 of the second switching element 32 is connected to the first power supply line 15 via a resistor 35. For this purpose, the control terminal 30 of the first switching device 24 is connected between the resistance 34 and the first terminal 33 of the first switching element 31. Thereby, the control terminal 30 of the second switching device 25 is connected between the first terminal 33 of the second switching element 32 and the resistor 35.

If a positive voltage representing the first signal state is thus applied to the input 2, the switching paths at the switching

elements

31, 32 become conductive, as a result of which the control terminals 30 of both switching

devices

24, 25 are at the potential of the second power supply line 16. As a result, on the one hand, the switching path of the first switching device 24 is conductive, and as a result, a charging current can flow. On the other hand, the second switching device 25 blocks to suppress the discharge current for the entire duration of the first signal state being present. Similarly, a low voltage applied to the input 2 and representing the second signal state causes the

switching elements

31, 32 to block, as a result of which the control terminals 30 of the

switching devices

24, 25 are pulled to the potential of the first power supply line 15. Accordingly, the switching path of the second switching device 25 becomes conductive for the entire duration of the presence of the second signal state, as a result of which a charging current can flow, while the first switching device 24 blocks to suppress a discharging current.

The circuit arrangement 1 further has a first diode 37 connected in series with a first resistor 38 between the first terminal 28 of the first switching device 24 and the capacitor 20, and also has a second diode 39 connected in series with a second resistor 40 between the first terminal 28 of the second switching device 25 and the capacitor 20. The forward direction of the

respective diode

37, 39 corresponds to the direction of the respective desired charging current. This prevents undesired discharge currents when the

switching devices

24, 25 are connected to the

respective diodes

37, 39 to conduct. The respective time constants of the charging currents are set by the

resistors

37, 40.

Furthermore, the circuit arrangement 1 has a capacitor 41 connected in parallel with the capacitance 20. The capacitance of the capacitor 41 is added to the capacitance 20, with the result that a suitable time constant for the charge reversal process of the operation of the circuit arrangement 1 is set by a suitable selection of the capacitance of the capacitor 41 and the values of the

resistors

38, 40.

Finally, the circuit arrangement 1 has a voltage limiting unit 42 which is connected in parallel with the capacitance 20 of the functional element 18 and is formed by two

zener diodes

43, 44 connected in series in opposite directions. In this case, the voltage limiting unit 42 limits the voltage applied to the control input 19 to the allowed maximum and minimum values of the functional element 18.

Fig. 2 is a graph of a waveform 45 of a voltage U, which is the voltage drop across the capacitance 20, with respect to time t during operation of the circuit arrangement 1. Here, a line 46 marks the voltage of the first power supply line 15 associated with the potential 11, and a line 47 marks the voltage of the second power supply line 16 associated with the potential 11. The voltage interval is indicated by reference character 45 a. The voltage of the switching line 17 changes frequently in relation to the potential 11 in dependence on the clock signal 14, so that its influence on the waveform 45 of the voltage U cannot be represented in a time-resolved manner in fig. 2.

The voltage waveform 45 across the capacitor 20 here qualitatively corresponds to the waveform of the control signal 3, the signal state changing much less frequently than the clock signal 14. It can be seen that the control input 19 has a clean control voltage (clean control voltage) that is limited to ± 17 volts by the voltage limiting unit 42. The waveform 45 has only a slight ripple 48 corresponding to the switching frequency of the clock signal 14, due to the undesired discharge current, which is suppressed but not completely prevented.

Fig. 3 is a circuit diagram of a second exemplary embodiment of the circuit arrangement 1, wherein components which are identical or have the same effect as compared to the first exemplary embodiment have the same reference numerals. In explaining the functions of this exemplary embodiment, it is assumed that the same as the external circuit shown in fig. 1 is used.

The circuit arrangement 1 is configured to limit the discharge current from the capacitance 20 to one of the

power supply lines

15, 16 when the respective signal state is present, in order to keep the voltage drop across the capacitance 20 outside the voltage interval, so that the voltage across the capacitance 20 always reliably implements one of the functions of the functional element 18. Compared to the first exemplary embodiment, there is no suppression of the discharge current. Thereby, the circuit arrangement 1 can be implemented more easily.

In contrast to the first exemplary embodiment, the second exemplary embodiment of the circuit arrangement has only one switching element 31 and one resistor 34. The control inputs 30 of both switching

devices

24, 25 are connected between the first terminal 33 of the switching element 31 and the resistor 34. In addition, in the first switching device 24, the first terminal 28 is connected to the first power supply line 15, and the second terminal 29 is connected to the capacitor 20 via the first diode 37 and the first resistor 38. In the second switching device 25, the first terminal 28 is connected to the second power supply line 16, and the second terminal 29 is connected to the capacitor 20 via a second diode 39 and a second resistor 40. As a result, the

switching devices

24, 25 can additionally be controlled in dependence on the potential at the control output 19. The

switching devices

24, 25 thus each implement a voltage follower, in which the potential at the second terminal 29 follows the potential at the control input 30. The transistor 26 of the first switching device 24 is correspondingly implemented as an npn bipolar transistor or, alternatively, as an n-channel field effect transistor. The transistor 26 of the second switching device 25 is correspondingly embodied as a pnp bipolar transistor or as a p-channel field effect transistor.

In contrast to the first exemplary embodiment, the control signal 3 is transmitted to the functional element 18 by complementary logic. If a sufficiently low voltage representing the first signal state is thus present at the input 3, the switching element 31 blocks and the control terminal 30 of the

switching device

24, 25 is pulled to the potential of the first power supply line 15. In this case, the charging current flows through the first switching device 24 and the first diode 37 to the capacitor 20. However, depending on the potential on the switching line 17, the limited discharge current flowing to the second power supply line 16 also temporarily flows through the second switching device 25, although this current is smaller than the charging current.

Similarly, when a positive voltage representing the second signal state is applied to the input terminal 3, the switching element 31 is turned on. In this case, the control terminal 30 of the

switching device

24, 25 is at the potential of the second power supply line 16. In this case, the charging current flows from the capacitor 20 through the second switching device 25 and the second diode 39 to the second power supply line. However, depending on the potential on the switching line 17, the limited discharge current flowing to the first power supply line 15 also temporarily flows through the first switching device 24, although this current is smaller than the charging current.

Fig. 4 is a graph of a waveform 49 of a voltage U, which is the voltage drop across the capacitance 20, versus time t during operation of the second exemplary embodiment, where the graph otherwise corresponds to fig. 2.

The voltage waveform 49 across the capacitor 20 here qualitatively corresponds to the waveform of the control signal 3. It can be seen that the control input 19 has a control voltage which is well defined with respect to the signal state and which is limited to-17 volts by the voltage limiting unit 42. The waveform 49 has a ripple 50 corresponding to the switching frequency of the clock signal 14, which is larger than the ripple 48 in the first exemplary embodiment. Therefore, the voltage interval 45a is also smaller than that in the first exemplary embodiment. The ripple is caused by the fact that the discharge current is only limited and not suppressed. However, for a large number of possible functional elements 19, a high ripple 50 can be tolerated.

Fig. 5 is a circuit diagram of a third exemplary embodiment of the circuit arrangement 1, wherein components which are identical or have the same effect as compared to the first exemplary embodiment have the same reference numerals. In explaining the functions of this exemplary embodiment, it is assumed that the same as the external circuit shown in fig. 1 is used.

The circuit arrangement 1 is configured to limit a discharge current from the capacitor 20 to one of the

power supply lines

15, 16 when the respective signal state is present. There is also no suppression of the discharge current, compared to the first exemplary embodiment. For this reason, the third exemplary embodiment of the circuit arrangement 1 can be implemented more easily than the first exemplary embodiment and the second exemplary embodiment.

In contrast to fig. 1, the third exemplary embodiment of the circuit arrangement 1 has only one switching element 31 and one resistor 34. The switching devices 24, 25 (refer to fig. 1) are omitted. The switching element 31 is configured to suppress a discharge current to the second power supply line 17 when the first signal state exists and to suppress a discharge current to the first power supply line 15 when the second signal state exists.

Furthermore, a resistance unit 51 is provided which connects the control input 19 to the switching element 31, the resistance value of which depends on the current direction of the current flowing through it. For this purpose, the resistance unit 51 has a series circuit composed of a first diode 52 and a first resistance 53, and a series circuit composed of a second diode 54 and a second resistance 55, the two series circuits being connected in parallel. In this case, the

diodes

52, 54 have opposite forward directions and the

resistors

53, 55 have different resistance values. An alternative configuration of the resistance unit 51 includes a first resistance connected in series with a parallel circuit composed of a diode and a second resistance, or the resistance unit 41 has a first resistance connected in parallel with a series circuit composed of a diode and a second resistance.

In contrast to the first exemplary embodiment, the control signal 3 is transmitted to the functional element 18 by complementary logic. If a sufficiently low voltage representing the first signal state is thus applied to the input terminal 2, the switching element 31 blocks and the resistive unit 51 is connected to the first power supply line 15. In this case, the charging current flows to the capacitor 20 through the first diode 52. However, depending on the potential on the switching line 17, the discharge current to the first power supply line 15 also temporarily flows through the second diode 54 although the current is smaller than the charge current.

Similarly, when a positive voltage representing the second signal state is applied to the input terminal 3, the switching element 31 is turned on. In this case, the resistance unit 51 is connected to the second power supply line 16. In this case, the charging current flows from the capacitor 20 to the second power supply line 16 through the second diode 54. However, depending on the potential on the switching line 17, the discharge current to the second power supply line 16 also temporarily flows through the first diode 52 although the current is smaller than the charge current.

In a third exemplary embodiment, the waveform of the voltage drop across the capacitance 20 substantially corresponds to the waveform 49 shown in fig. 4.

FIG. 6 is a basic schematic diagram of an exemplary embodiment of a vehicle 56 having an exemplary embodiment of a power converter 57.

The power converter 57 comprises three half-bridges 58, each having two series-connected power switching elements 9, wherein the control terminal 8 of the respective power switching element 9 is connected to the circuit arrangement 1 according to one of the above-described exemplary embodiments. For each power switching element 9, there is also provided a voltage supply unit 2a and a driver unit 6a configured to control the control terminal 8 of the power switching element 9 via a switching line 17. The voltage supply unit 2a is here configured for jointly supplying the driver unit 6a and the circuit arrangement 1 via their first power line 15 and second power line 16. For the sake of clarity, the circuit arrangement 1, the voltage supply unit 2a and the driver unit 6a are shown in fig. 6 for only one power switching element 9.

The power converter 57 further has a control unit 59 configured to provide the control signals 3 for all circuit arrangements 1 and the clock signals 14 for the respective driver units 6 a.

The vehicle 56 is a hybrid or electric vehicle that includes an electric motor 60, the electric motor 60 being configured to drive the vehicle and being powered by a power converter 57. For this reason, the power converter converts the DC voltage supplied from the high-voltage battery 61 into a three-phase AC voltage for the motor 60.

Claims

1. A circuit arrangement (1) for transmitting a control signal (3) from an input (2) of the circuit arrangement (1) to a functional element (18) of the circuit arrangement (1), the circuit arrangement comprising:

-a first power supply line (15) for a first potential,

-a second power supply line (16) for a second potential, the second potential being different from the first potential,

-a switching line (17) which can be alternately connected to the first power supply line (15) and to the second power supply line (16),

wherein the functional element (18) has a control input (19) and a capacitance (20) between the control input (19) and the switching line (17),

characterized in that the circuit arrangement (1) is configured to,

-in the presence of a first signal state of the control signal (3), when the switching line (17) is at the second potential, charging the capacitance (20) to a first target voltage via the first power supply line (15) by means of a charging current, and when the switching line (17) is at the first potential, limiting a discharging current flowing from the capacitance (20) to one of the power supply lines (15, 16) opposite to the charging current, to keep a voltage drop across the capacitance (20) beyond a first threshold outside a voltage interval defined by a first voltage threshold and a second voltage threshold for the function of the functional element (18), and

-in the presence of a second signal state of the control signal (3), when the switching line (17) is at the first potential, charging the capacitance (20) to a second target voltage, which complements the first target voltage, via the second power supply line (16) by means of a charging current, and when the switching line (17) is at the second potential, limiting a discharging current flowing from the capacitance (20) to one of the power supply lines (15, 16), opposite to the charging current, to keep the voltage drop across the capacitance (20) beyond a second threshold outside the voltage interval.

2. The circuit arrangement of claim 1, designed to suppress the discharge current in the presence of a respective signal state.

3. Circuit arrangement according to claim 1 or 2, having a switching device (24) which can be controlled in dependence on the control signal (3), the switching device (14) being connected between the first power supply line (15) and the control input (19) and being configured to conduct when the switching line (17) is at the second potential in the presence of the first signal state.

4. The circuit arrangement according to claim 3, wherein the switching device (24) is configured to block for the entire duration of the presence of the second signal state.

5. Circuit arrangement according to any of the preceding claims, having a switching device (25) which can be controlled in dependence on the control signal (3), the switching device (15) being connected between the control input (19) and the second power supply line (16) and being configured to conduct when the switching line (17) is at the first potential in the presence of the second signal state.

6. The circuit arrangement according to claim 5, wherein the switching device (25) is configured to block for the entire duration of the presence of the first signal state.

7. Circuit arrangement according to claim 3 or 5, wherein both of the switching devices (24, 25) or the respective switching devices (24, 25) can additionally be controlled depending on the potential at the control input (19) of the functional element (18).

8. Circuit arrangement according to one of the preceding claims, when dependent on claims 3 and 5, wherein a respective diode (37, 39) is connected between the respective switching device (24, 25) and the control input (19), wherein the diodes have opposite forward directions.

9. The circuit arrangement according to claim 8, wherein a resistor (38, 40) is connected in series with the respective diode (37, 39), wherein the resistors (38, 40) have different resistance values.

10. Circuit arrangement according to one of the preceding claims, having one or two switching elements (31, 32) on the input side, wherein both or the respective switching elements are connected to the supply lines (15, 16) via resistors (34, 35).

11. Circuit arrangement according to claim 10, when dependent on claim 3 and/or claim 5, wherein the control terminal (30) of both switching devices (24, 25) or of the respective switching device (24, 25) is connected between both switching elements (31, 32) or of the respective switching element (31, 32) and the resistance (34, 35).

12. The circuit arrangement of claim 10, having a resistance unit (51), the resistance unit (51) connecting the switching element (31) and the control input (19) to each other.

13. Circuit arrangement according to claim 12, wherein the resistance value of the resistance unit (51) depends on the current direction through the resistance unit.

14. Circuit arrangement according to one of the preceding claims, wherein the functional element (18) is an electronically controlled switching tube (21).

15. The circuit arrangement according to claim 14, having a resistance (22) in the switching line, wherein the electronically controlled switching tube (21) is connected in series with a further resistance (23) to connect the two resistances (22, 23) in parallel depending on the control signal (3).

16. Circuit arrangement according to one of the preceding claims, having a capacitor (41) connected in parallel with the capacitance (20) of the functional element (18).

17. Circuit arrangement according to one of the preceding claims, having a voltage limiting unit (42) connected in parallel with the capacitance (20) of the functional element (18).

18. A power converter (57) comprising

-at least two half bridges (58), each of the at least two half bridges having two series-connected power switching elements (9),

-a circuit arrangement (1) according to one of the claims 1 to 17,

-a driver unit (6a) configured to actuate a control terminal (8) of one of the power switching elements (9) via a switching line (17), and

-a voltage supply unit (2a) configured for jointly powering the driver unit (6a) and the circuit arrangement (1) via a first power supply line (15) and a second power supply line (17).

19. A vehicle (56), in particular a hybrid vehicle or an electric vehicle, the vehicle (56) comprising an electric motor (60) configured to drive the vehicle (56) and a power converter (57) according to claim 18 for supplying power to the electric motor (60).