EP3891857A1

EP3891857A1 - Device and method for discharging a dc link capacitor

Info

Publication number: EP3891857A1
Application number: EP19798276.2A
Authority: EP
Inventors: Marco DENK; Stefan Hain
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2018-12-07
Filing date: 2019-11-05
Publication date: 2021-10-13
Also published as: WO2020114696A1; CN211809095U; DE102018221209A1; US20220029526A1

Abstract

The present invention relates to a device (105) for discharging a DC link capacitor (140), the device (105) having a discharging unit (145) for discharging the DC link capacitor (140), the discharging unit (145) being connected or connectable between two connection terminals (155) of the DC link capacitor (140), discharging of the DC link capacitor (140) being controllable by means of a control voltage (U_ge) applied to a control input (160) of the discharging unit (145). The device (105) also comprises a control unit (150), which is designed to apply the control voltage (U_ge) to the control input (160) of the discharging unit (145), wherein the control unit (150) is further designed to vary the control voltage (U_ge) during a discharging process or at the start of a process for discharging the DC link capacitor (125).

Description

Device and method for discharging an intermediate circuit capacitor

The present invention relates to an apparatus and a method for discharging an intermediate circuit capacitor according to the main claims.

An intermediate circuit capacitor in a power electronic drive train should be able to be discharged in a controlled manner in the event of a fault for safety reasons. For example, a permanent passive discharge through high-resistance resistors or a redundant, active discharge circuit is used. The active discharge circuit can, for example, a plurality of power resistors which absorb the energy of the intermediate circuit capacitor and / or comprise a high-voltage semiconductor switch which interconnects the load resistors with the intermediate circuit capacitor if necessary. This technology can be used for systems up to 400V, for example.

The problem for 800V systems is that the high-voltage semiconductor switch and the load resistances become significantly larger because the DC link capacitor contains four times the energy with the same capacity.

Against this background, the present invention provides an improved device and an improved method for discharging an intermediate circuit capacitor according to the main claims. Advantageous embodiments result from the subclaims and the following description.

A device for discharging an intermediate circuit capacitor is presented, the device comprising the following features:

- A discharge unit for discharging the intermediate circuit capacitor, the discharge unit being switchable or connected between two connecting terminals of the intermediate circuit capacitor, wherein a discharge of the intermediate circuit capacitor can be controlled by a drive voltage applied to a control input of the discharge unit; and

- A control unit, which is designed to act upon the control input of the discharge unit with the control voltage, the control unit is further configured to change the drive voltage during a discharge process or to start a discharge process of the intermediate circuit capacitor.

A discharge unit can be understood to mean, for example, a unit or an element which enables a current to flow in response to a control signal in order to discharge the intermediate circuit capacitor in a discharge process. For example, the discharge unit can be a semiconductor component, in particular from the field of power electronics. A control unit can be understood to mean a unit, in particular an electronic unit, which generates the control voltage in accordance with a predetermined regulation or circuit topology. The control voltage can be generated, for example, numerically or in terms of circuitry. For example, a component or an element of an inverter can be used as the discharge unit.

The approach proposed here is based on the knowledge that a discharge unit, for example depending on a current temperature, can have a different switching behavior, so that by operating the control input of the discharge unit with a variable control voltage, a working point of the discharge unit is reliably controlled , in which a safe discharge of the intermediate circuit capacitor is achieved. The approach presented here has the advantage of being able to safely discharge the intermediate circuit capacitor in different application scenarios using technically simple and inexpensive means, in response to the control signal or the control voltage.

The approach presented here thus offers a solution of how the redundant, active discharge according to one embodiment can be implemented, for example, as part of the inverter by suitable control of semiconductor switches as the discharge unit. Corresponding load resistors and an associated high voltage load resistor can be saved. The power semiconductor (s) as an embodiment of the discharge unit is / are se operated in the linear range and set a defined resistance and discharge current for discharging the intermediate circuit capacitor.

According to one aspect of the approach presented here, it is thus possible to implement a particularly simple and functional control method for power semiconductors as an embodiment of a discharge unit in order to carry out an active discharge of the intermediate circuit capacitor in a controlled manner. It is therefore proposed according to an embodiment of the approach presented here a novel Ansteuerver drive the discharge unit, for example in the form of a power semiconductor, in order to be able to integrate the function of a redundant, active discharge of the intermediate circuit capacitor into the control.

According to a particularly favorable embodiment, the control unit can be designed to change the control voltage from a low voltage level to a high voltage level. In this way, the discharge unit can advantageously be controlled such that the intermediate circuit capacitor is discharged as quickly and safely as possible via the discharge unit.

According to a further embodiment, the control unit can also be designed to change the control voltage uniformly, linearly and / or monotonously, in particular strictly monotonously. In this way it can be ensured, for example, that the discharge unit is controlled for a sufficiently long time in an optimal voltage range of the control voltage so that the intermediate circuit capacitor can be discharged reliably and quickly. At the same time, such a control voltage can be provided in a technically simple and efficient manner.

An embodiment of the approach proposed here is particularly advantageous in which the control unit has an RC element in order to determine a voltage level of the control voltage. Such an embodiment is technically very simple to implement.

According to a further embodiment of the approach presented here, the control unit can be designed to operate at or for a start of discharge. tion process to cause a voltage jump in the drive voltage and / or to cause a voltage jump in the drive voltage after an end of the discharge process. Such an embodiment offers the advantage of actuating the discharge unit in such a way that no inadvertent discharge of the intermediate circuit capacitor occurs before the desired start of the discharge process and / or after the end of the discharge process the discharge unit can be brought quickly back into a state in which the intermediate circular capacitor can be recharged.

In this context, an embodiment of the approach presented here is particularly advantageous, in which the control unit is designed to set the control voltage to a level of 0 volts at the start of the discharge process, in particular starting from a minimum value that occurs before the start of the Discharge process has applied to the control input of the discharge unit and / or wherein the control unit is designed to set the control voltage to a minimum value after an end of the discharge process, in particular based on a maximum value that at one end of the discharge process at the control input of the Discharge unit has created. In this way, the discharge unit can be controlled in such a way that the discharge of the intermediate circuit capacitor is as safe as possible at the desired discharge times or discharge time intervals, while at the other times or time intervals a discharge of the intermediate circuit capacitor can be avoided as reliably as possible.

According to another embodiment of the approach proposed here, the discharge unit can be designed as a semiconductor switch, in particular a power semiconductor switch. In this way, the discharge of the intermediate circuit capacitor can be controlled very quickly and simply. At the same time, this semiconductor switch can, for example, be part of an inverter of the intermediate circuit, so that components of the intermediate circuit that are already in use can be used for additional functionality and additional, separate components can thereby be saved, as a result of which the approach presented here can be implemented very inexpensively. Very cheap The semiconductor switch can also be operated in a linear (characteristic) range, so that the technical functions of the semiconductor switch can be used as efficiently as possible for the discharge process of the intermediate circuit, for example for converting the electrical energy stored in the intermediate circuit capacitor into thermal energy.

According to a further embodiment of the approach presented here, the discharge unit can also be designed as a transistor, in particular a MOSFET transistor, or an IGBT. Such an embodiment offers the advantage of a particularly fast and reliable control possibility of the discharge unit or the discharge of the intermediate circuit capacitor, wherein, for example, how a component of the intermediate circuit can be used for the further function as a discharge unit, which increases the manufacturing costs for the implementation of the approach presented here can be reduced.

In a further embodiment of the approach presented here, the control unit can be designed to determine the control voltage as a function of a temperature of the discharge unit or a component of the discharge unit. Such an embodiment offers the advantage of controlling an optimal operating point of the discharge unit as quickly as possible with a suitable control voltage, so that the intermediate circuit capacitor can be discharged as quickly as possible.

The approach proposed here can be implemented in a particularly simple and inexpensive manner if a circuit topology is used in which the control unit has at least two resistors, one of the resistors being connectable in parallel with the other of the resistors by means of a first switch or being coupled to the control input of the discharge unit or can be coupled and / or wherein the control unit has a capacitance that can be switched or switched between the control input of the discharge unit and a connection of the intermediate circuit capacitor, in particular wherein the capacitance has a second switch for parallel connection of the capacitance between the control input and the Connection of the intermediate circuit capacitor to effect. Such an The form of implementation of the approach presented here has the advantage of being able to use technically simple means to provide the desired change in the drive voltage during the discharge process or to initiate the discharge process.

An embodiment of the approach proposed here can be used particularly efficiently in an intermediate circuit for transmitting electrical energy from an energy source to an actuator, the intermediate circuit having an intermediate circuit capacitor and a device coupled to the intermediate circuit capacitor according to a variant presented here, in particular wherein the device uses at least one component which is also used by an inverter connected to the intermediate circuit capacitor. The component used by the inverter can be used here as the discharge unit of the device. Such an embodiment offers the advantage of being able to discharge the intermediate circuit capacitor efficiently, quickly and reliably through the device.

Another advantage is an embodiment of the approach proposed here as a method for discharging an intermediate circuit capacitor by means of a variant of a device presented here, the method having the following step:

- Actuation of the control input of the discharge unit with a control voltage, the charging being carried out in such a way that the control voltage is changed during or for a start of a discharge process of the intermediate circuit capacitor.

Even with such an embodiment, the advantages of the approach presented here can be realized quickly and efficiently.

An embodiment of the approach presented here as a control device, which is set up to execute and / or to control the step of a variant of a method presented here in a corresponding unit, is also favorable. A control device can be an electrical device that processes electrical signals, for example sensor signals, and outputs control signals as a function thereof. The control device can have one or more suitable interfaces, which can be designed as hardware and / or software. In the case of a hardware configuration, the interfaces can, for example, be part of an integrated circuit in which functions of the device are implemented. The interfaces can also be separate integrated circuits or at least partially consist of discrete components. In the case of software-based training, the interfaces can be software modules which are present, for example, on a microcontroller next to their software modules.

Also advantageous is a computer program product with program code, which can be stored on a machine-readable medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out the method according to one of the above-described embodiments when the program is on a computer or a control unit.

The invention is explained in more detail by way of example with reference to the accompanying drawings. Show it:

1 shows a schematic representation of a vehicle in which a device for discharging a dual-circuit capacitor according to an exemplary embodiment can be used;

Figure 2 is a diagram showing the modulation behavior of a power semiconductor as a discharge unit.

3 shows a schematic illustration of a profile of the control voltage;

4 shows a diagram corresponding to the diagram from FIG. 2, but it can now be seen that an optimal operating point or an optimal gate voltage is achieved on a characteristic curve by the variable gate voltage;

5 shows a possible circuit topology which can be used for the simple and inexpensive implementation of the approach presented here; FIG. 6 shows a diagram to show different electrical quantities over time for a deeper understanding of the function of the circuit from FIG. 5; and FIG. 7 shows a flow chart of a method according to an exemplary embodiment.

In the following description of preferred exemplary embodiments of the present invention, the same or similar reference numerals are used for the elements which have a similar effect and which are shown in the various figures, a repeated description of these elements being dispensed with.

FIG. 1 shows a schematic illustration of a vehicle 100, in which a device 105 for discharging an intermediate circuit capacitor according to one exemplary embodiment can be used. The vehicle 100 is configured, for example, as a hybrid or electric vehicle. The vehicle 100 is supplied with electrical energy by a battery or an accumulator as an energy store 110, which for example feeds a voltage UB of 400 volts or, in newer vehicles, 800 volts into an energy supply system 115 of the vehicle 100. In order to be able to operate a drive motor 120 of the vehicle 100 with this energy from the energy store 110, an intermediate circuit 125 with an inverter 130 is often required in order, for example, to feed the energy supply system 115 of the vehicle 100 from the energy source 110 as DC voltage Energy to generate an alternating voltage, in particular a multi-phase alternating voltage in a drive energy supply system 135 for operating the drive motor 120. For this purpose, the inverter 130 can have one or more bridge circuits (not shown in FIG. 1 for reasons of clarity) in order to determine the suitable AC voltage for injection into the drive power supply system 135 from the DC voltage UB from the energy supply system 115.

In order to avoid or smooth out fluctuations in the voltage UB in the energy supply system 115 with a changing load of the drive motor 120, an intermediate circuit capacitor 140 is provided. This intermediate circuit capacitor 140 is usually designed in such a way that it can absorb a large amount of energy in order to compensate for the corresponding fluctuations in the voltage UB in the energy supply interception system 115 intercept. However, if a fault occurs in the electrical system of the vehicle 100, for example a short circuit or an electrical defect, it may be necessary for safety reasons to discharge the intermediate circuit capacitor 140 as quickly as possible, for example to avoid the risk of fire of the vehicle 100 or the risk of to minimize electric shock for occupants of vehicle 100 due to the high electrical voltage that may still be present in intermediate circuit capacitor 140. For this purpose, a corresponding protective circuit is usually used, as is the device 105 presented here for discharging the intermediate circuit capacitor 140.

The device 105 for discharging the intermediate circuit capacitor 140 has a discharge unit 145 and a control unit 150. The discharge unit 145 can be connected, for example, between terminals 155 of the intermediate circuit capacitor 140, wherein a discharge of the intermediate circuit capacitor 140 can be controlled by the discharge unit 145 by means of a drive voltage applied to a control input 160. The control unit 150 is designed to apply the control voltage to the control input 160 of the discharge unit 145, the control unit 150 providing the control voltage in such a way that the control voltage during the discharge process or for a discharge (ie for starting the discharge) of the intermediate circuit capacitor 140 is changed.

In order to initiate a discharge of the intermediate circuit capacitor 140, for example in response to an error detected by an error detection unit 165 and transmitted to the control unit 150 by means of an error signal 170, for example a defect in the electrical system of the vehicle 100, the corresponding control voltage U in the control unit 150 _be generated and applied to the control input 160 of the discharge unit 145, as will be described in more detail below.

If a power semiconductor is now used as the discharge unit 145, for example that which is part of the inverter 130 or a bridge circuit of the inverter 130, a problem can be encountered with regard to controlled activation of the latter Power semiconductors occur so that instead of its nominal current (a few hundred amperes) carries only a very small current (a few hundred milliamps). For this purpose, the gate voltage U _{ge of} this power semiconductor (ie the voltage between the gate and the source connection of the power semiconductor used as a discharge unit 145), which sets the current flow I in the power semiconductor, should be at a certain constant value (U _{ge, const} ) can be set. As for egg NEN desired low discharge current controls the necessary gate voltage U _ge of many Parameteren such as temperature and manufacturing tolerances depends, is the active discharge by applying a pre-defined Ga te voltage U _ge not possible.

FIG. 2 shows a diagram to illustrate the modulation behavior of a power semiconductor as a discharge unit 145, in which the gate voltage U _g e is plotted on the abscissa and the current l _c flowing through the power semiconductor is plotted on the ordinate. Furthermore, three characteristic curves 200 are entered in the diagram, a first 200 a of the characteristic curves 200 showing the current flow l _c as a function of the gate voltage U _ge at a temperature of 150 ° C. of the power semiconductor, and a second 200 b of the characteristic curves 200 the current flow l _c as a function of gate voltage U _g e at a temperature of 25 ° C of the power semiconductor and 200 the flow of current l _c _ge function of the gate voltage U at a temperature of -40 ° C of the power semiconductor maps drit te 200c of the characteristic curves. It can be seen from FIG. 2 that the discharge current 210 required to discharge the intermediate circuit capacitor 140 is reliably reached only for the temperature 25 ° C. of the power semiconductor; in the event that the power semiconductor has a temperature of -25 ° C., the constant gate voltage U _{ge is} too low, while for the temperature 150 ° C. of the power semiconductor the constant gate voltage U _{ge is} too high.

Figure 2 thus illustrates the problem using the example of the reliable control of the discharge unit 145 using the example of a power semiconductor as a discharge unit at a variable temperature, which has the greatest influence on the discharge current. FIG. 2 thus shows the problem of the uncontrollable discharge current. mes lc at a constant gate voltage (U _ge , konst) of a discharge unit 145 in the form of a power semiconductor as a function of the temperature.

In other words, in the exemplary embodiment shown in FIG. 2, the constant gate voltage (U _ge , konst) is set for a temperature of 25 ° C. in such a way that the desired discharge current l _c flows. However, if the semiconductor becomes too hot (T = 150 ° C.), an excessively high discharge current flows over the semiconductor or the semiconductor of the discharge unit 145 at the same applied gate voltage, as a result of which they can be damaged or destroyed. For low temperatures (T = -40 ° C) the problem may arise that the gate voltage is not sufficient to open the electron channel of the semiconductor as a discharge unit 145 and no discharge current l _{c flows} . This problem means that an active discharge via the power semiconductor could not be used as the discharge unit 145.

In order to counter this problem of the parameter-dependent gate voltage for a constant and controlled discharge current, a new control method is proposed here according to an exemplary embodiment. The discharge unit 145, which is embodied here as a semiconductor, is not driven with a constant gate voltage, but with a variable drive voltage, such as a gate voltage ramp.

FIG. 3 shows a schematic illustration of a profile 300 of the control voltage, as can be applied to the control input 160 of the discharge unit 145 in accordance with an exemplary embodiment of the approach presented here. The time t is plotted on the abscissa of the diagram shown in FIG. 3 and the gate voltage U _ge on the ordinate. The linear or monotonous or even strictly monotonically increasing profile of the gate voltage U _{ge can be seen} for increasingly later times t, the time in the original corresponding to a time of activation of the discharge process, for example in response to the error signal 170. The gate voltage U _ge is thus impressed on the control input 160 as a variable control voltage or gate voltage voltage ram. The use of such a variable gate voltage U _ge as the control voltage applied to the control input 160, for example in the form of the gate voltage ramp according to an exemplary embodiment of the approach presented here, makes it possible to increase the control voltage as a function of time with a fixed gradient, so that all relevant gate voltages U _ge are gradually passed through. This control leads to the fact that the gate voltage U _ge , which opens the electron channel and the flow of the optimal discharge current lc through the discharge unit 145, is applied to the semiconductor as the discharge unit 145, regardless of its temperature and its parameters leads as the semiconductor, so that the inter mediate circuit capacitor 145 can be discharged.

FIG. 4 shows the diagram corresponding to the diagram from FIG. 2, but it can now be seen that the variable gate voltage U _{ge means that} an optimal operating point or an optimal gate voltage on one of the characteristic curves 200 is independent of the current temperature of the semiconductor as a discharge unit 145 it is sufficient, which leads to the opening of the discharge unit 145 in the form of a semiconductor, so that the intermediate circuit capacitor 130 can be discharged reliably and quickly. FIG. 4 thus shows an optimal control of the semiconductor as a discharge unit 145 by means of the exemplary variable gate voltage ramp as the control voltage to be impressed on the control input 160. For each temperature of the semiconductor as the discharge unit 145, the desired or required discharge current 210 is thus achieved quickly and reliably.

The slope of the ramp can be used to set how quickly the electron channel of the semiconductor used as the discharge unit 145 is to be opened and thus how dynamically the discharge process of the intermediate circuit capacitor 140 is to be carried out.

FIG. 5 shows a possible circuit topology 500 which can be used for the simple and inexpensive implementation of the approach presented here. The circuit topology 500 can be used as a circuit concept for generating the variable control voltage, for example as a gate voltage ramp. will stand. However, the control voltage or gate voltage voltage can also be implemented by other means, for example by numerical or digital control of corresponding voltage sources. The circuit structure 500 shown in FIG. 5, however, offers a very simple way of realizing the approach proposed here.

The control circuit or control unit 150 of the semiconductor (as discharge unit 145) is supplemented by four further components, namely the first switch S1, the second switch S2, a capacitance CAD and a resistor RAD, the two switches S1 and S2 in, for example Depending on the error signal 170 can be closed or opened by means of a switch control unit 510. Here, as the discharge unit 145, for example, a semiconductor or power semiconductor (here, for example, a MOSFET voltage transistor) is used, which is also part of the inverter 130, for example a bridge circuit of the inverter 130 for converting the DC voltage U _B into an AC voltage for operating the drive motor Can be 120.

In normal switching operation (ie if there is no fault), first switch S1 is closed and second switch S2 is open. Since the resistor RAD SO is selected so that it is much larger (for example by a factor of 10) than the gate resistor R _g , the switching behavior of the semiconductor as the discharge unit 145 is not influenced by the parallel connection of RAD and R _g . Due to the opened second switch S2, the capacitance CAD is not effective. If the intermediate circuit 125 or the intermediate circuit capacitor 140 is to be discharged, this is initiated, for example, by the error signal 170 and the switch control unit 510 controls a voltage source in order to switch a control voltage Us to a positive control voltage, the first switch S1 being opened and the second switch S2 is closed. Since the capacitance of CAD is advantageously much larger (for example by a factor of 10) than the gate-source capacitance of the semiconductor as discharge unit 145, the voltage of the gate-source capacitance is immediately matched to the voltage of the capacitance CAD (for example by a typical jump from -5V to 0V). The further course of the gate voltage U _ge is determined by charging the RC timing element consisting of RAD and CAD, as a result of which the desired gate voltage ramp U _ge , for example, as shown in Figure 4 is reached.

FIG. 6 shows a diagram of different electrical quantities plotted on the ordinate on the left (voltages Uce, U _g e and current lc) and on the right (power loss or energy loss) of the diagram over the time t plotted on the abscissa for a deeper understanding of the function of the Circuit from FIG. 5. Here, the discharge concept of the approach presented here is illustrated on the basis of measurement results and a functional proof of the drive-integrated, active discharge concept presented here.

The discharge circuit is activated at the time t = 0s, as a result of which the gate voltage (characteristic curve 600) jumps to the value 0V at the time Os. The gate voltage ramp is then impressed. In the area 610, the channel of the semiconductor acting as a discharge unit 145 begins to open and a controlled discharge current (characteristic line 620) flows, which is a maximum of 1A. The voltage of the intermediate circuit Uce (characteristic curve 630) drops due to the discharge current lc within a discharge time interval t _d of 0.7 s from 800 V to 0 V. Here, a power loss pi _oss of 500W at iner waste energy ei _oss of 200 J is reduced.

An important aspect of the approach presented here can be seen in that the discharge unit (which is realized here as a semiconductor) can be controlled via a variable drive voltage, such as a gate voltage ramp, for triggering an active discharge of the intermediate circuit capacitor 140. The variable ansteroid voltage or ramp can be generated by different variants, such as an RC element with an applied voltage or a defined current source. The great advantage of such an exemplary embodiment is that all discharge unit types, such as, for example, semiconductor types (Si-IGBTs, Si-MOSFETs and SiC-MOSFETs) that can be used favorably, in many relevant voltage classes (650 V,

1200V, 1700V) can be used to implement a redundant, control-integrated, active discharge circuit according to the concept proposed here. FIG. 7 shows a flowchart of an exemplary embodiment as a method 700 for discharging an intermediate circuit capacitor by means of a variant of a device presented here, the method 700 having the step 710 of applying a control voltage to the control input of the discharge unit, the charging being carried out in such a way that the control voltage is changed during a discharge process or to start a discharge process of the intermediate circuit capacitor.

The exemplary embodiments described and shown in the figures are selected only in a playful manner. Different exemplary embodiments can be combined with one another completely or with regard to individual features. An exemplary embodiment can also be supplemented by features of a further exemplary embodiment.

Furthermore, method steps according to the invention can be repeated and carried out in a sequence other than that described.

If an exemplary embodiment comprises a “and / or” link between a first feature and a second feature, this can be read in such a way that the embodiment according to one embodiment has both the first feature and the second feature and according to a further embodiment either only that has the first feature or only the second feature.

Reference sign

100 vehicle

105 Unloading device

110 energy storage

115 energy supply system

120 drive motor

125 DC link

130 inverters

135 traction power supply system

140 DC link capacitor

145 discharge unit

150 control unit

155 terminals

160 control input

165 Error detection unit

170 error signal

200, 200a, 200b, 200c characteristics

210 discharge current

300 Course of the control voltage

500 circuit topology

510 switch control unit

51 first switch

52 second switch

CAD capacity

R _AD resistance

600 characteristic

610 characteristic

620 characteristic Kennline Procedure for discharging an intermediate circuit capacitor step of loading

Claims

1 . Device (105) for discharging an intermediate circuit capacitor (140), the device (105) comprising the following features:

- A discharge unit (145) for discharging the intermediate circuit capacitor (140), the discharge unit (145) being switchable or connected between two connecting terminals (155) of the intermediate circuit capacitor (140), with a discharge of the intermediate circuit capacitor (140) by a at a control input (160) of the discharge unit (145) applied control voltage (U _ge ) is controllable; and

- a control unit (150) is formed for acting upon the Ansteuereingangs (160) of the discharge unit (145) _(ge U) with the driving voltage, wherein the control unit (150) is further configured _(ge U) to the driving voltage during a discharge operation or to change the start of a discharge process of the intermediate circuit capacitor (125).

2. Device (105) according to claim 1, characterized in that the control unit (150) is designed to change the control voltage (U _ge ) from a low voltage level to a high voltage level.

3. Device (105) according to one of the preceding claims, characterized in that the control unit (150) is designed to change the control voltage (U _ge ) uniformly, linearly and / or monotonously, in particular strictly monotonously.

4. Device (105) according to any one of the preceding claims, characterized in that the control unit (150) has an RC element in order to determine a voltage level of the control voltage (U _ge ).

5. The device (105) according to any one of the preceding claims, characterized in that the control unit (150) is designed to cause a voltage jump in the control voltage (U _ge ) at a start or for a start of the discharge process and / or after to cause a voltage jump in the drive voltage (U _ge ) at one end of the discharge process.

6. The device (105) according to claim 5, characterized in that the control unit (150) is designed to set the control voltage (U _ge ) to a level of 0 volts, in particular starting from a minimum, at the start of the discharge process Value which was applied to the control input (160) of the discharge unit (150) before the start of the discharge process and / or where the control unit (150) is designed to reduce the control voltage (U _ge ) to a minimum value after the end of the discharge process to be set, in particular starting from a maximum value which has applied to the discharge input (160) of the discharge unit (150) at one end of the discharge process.

7. Device (105) according to any one of the preceding claims, characterized in that the discharge unit (145) is designed as a semiconductor switch, in particular a power semiconductor switch.

8. The device (105) according to claim 7, characterized in that the discharge unit (145) is designed as a transistor, in particular a MOSFET transistor, or an IGBT.

9. The device (105) according to any one of the preceding claims, characterized in that the control unit (150) is designed to the control voltage (U _g e) as a function of a temperature (T) of the discharge unit (145) or to determine a component of the discharge unit (145).

10. The device (105) according to any one of the preceding claims, characterized in that the control unit (150) has at least two resistors (RAD, Rg), one of the resistors (R _g ) by means of a first switch (S1) with the other (RAD) of the resistors can be connected in parallel with the control input

(160) of the discharge unit (145) is coupled or can be coupled and / or the control unit (150) has a capacitance (CAD), which is between the control input (160) of the discharge unit (145) and a connection (155) of the intermediate circuit capacitor (140) is switchable or switched, in particular wherein the capacitance (CAD) has a second switch (S2) in order to connect the capacitors in parallel. zity (CAD) between the control input (160) and the connection (155) of the intermediate circuit capacitor (140) to effect.

1 1. Intermediate circuit (125) for transmitting electrical energy from an energy source (110) to an actuator (120), the intermediate circuit (125) comprising an intermediate circuit capacitor (140) and a device (105) coupled to the intermediate circuit capacitor (140) according to one of the preceding claims, in particular in particular wherein the device (105) uses at least one component (145) which is further used by an inverter (130) connected to the intermediate circuit (125).

12. A method (700) for discharging an intermediate circuit capacitor (140) by means of a device (105) according to one of the preceding claims 1 to 10, the method (700) comprising the following step:

- Acting (710) of the control input (160) of the discharge unit (145) with a control voltage (U _ge ), the charging being carried out in such a way that the control voltage (U _ge ) during a discharge process or to start a discharge process of the intermediate circuit capacitor (140 ) is changed.

13. Control device (510), which is set up to execute the step (710) of the method (700) according to claim 12 in a corresponding unit

and / or to control.

14. Computer program that is set up to execute and / or to control the step (710) of the method (700) according to claim 12 in a corresponding unit.

15. Machine-readable storage medium on which the computer program according to claim 14 is stored.