Protective device for load resistors

Abstract

The invention relates to a protection device (1) for operating an electric machine (33) at a converter (3), comprising a first and a second conductor (4, 5) of a DC voltage intermediate circuit (2), a switching device (6) having a first and a second switch (7, 8), an intermediate circuit capacitor (9), a load resistor (10) as a precharging and braking resistor, a semiconductor switch (11) and an electrical fuse (12) for protecting the load resistor (10), wherein the electrical fuse (12) and the first switch (7) are electrically connected as a series circuit to the first conductor (4) on the one hand, and On the other hand, it is electrically connected to a first resistor connection (13) of the load resistor (10) and a first power connection (14) of the semiconductor switch (11), wherein the second switch (8) is electrically connected to the first conductor (4) on the one hand and to a first capacitor connection (15) of the intermediate circuit capacitor (9) and a second resistor connection (16) of the load resistor (10) on the other hand, and wherein the semiconductor switch (11) is electrically connected to the second conductor (5) by means of a second power connection (17) and the intermediate circuit capacitor (9) is electrically connected to the second capacitor connection (18) respectively. The invention also relates to a method (42) for operating the protection device (1) and a converter (3) having the protection device (1).

Description

Technical Field

[0001] The invention relates to a protection device for operating an electric motor at a converter, wherein the protection device protects a load resistor which can be operated as a braking resistor in the case of a generator brake by means of a semiconductor switch and which can be used as a precharging resistor for precharging an intermediate circuit capacitor at a DC intermediate circuit. Background Art

[0002] In particular, electrical converters which are also used in safety-related drive systems in industrial environments must be put into a safe operating state in the event of a fault and can only be put back into operation after the fault has been eliminated.

[0003] Not every converter is able to feed back the electrical energy generated by a motor operated by the converter, for example during braking operation, into the grid in a manner dependent on or conditional on the grid dimensioning of the electrical supply grid.

[0004] In order to neutralize the excess electrical energy generated as a generator without damaging the converter, a braking resistor is usually used in the DC voltage intermediate circuit of the converter. The braking resistor converts the electrical energy into heat energy, which is released into the environment by the braking resistor.

[0005] If the entire regenerative power during the braking operation is absorbed by the braking resistor and converted into heat, the braking resistor can be dimensioned accordingly to the required performance data. However, this is a very expensive and space-consuming solution with regard to the braking resistor.

[0006] Another known solution is that the brake resistor absorbs excess electrical energy in a metered manner with the aid of a clocked semiconductor switch and gently converts this electrical energy into heat energy for the brake resistor. Therefore, in order not to overload the brake resistor and prevent it from being damaged, a metered conversion of electrical energy into heat energy is used. This solution is also called a brake resistor with a brake chopper (here a semiconductor switch).

[0007] During operation of a semiconductor switch that is controlled in a clocked manner, which absorbs the electrical energy generated as a generator and converts it into heat for the metered control of a braking resistor, the semiconductor switch fails in the event of a fault. This means that the drain-source path or collector-emitter path of the semiconductor switch, i.e. the supply path, remains permanently closed despite the opening command. As a result, an unintentional short circuit can occur at the semiconductor switch.

[0008] Since the braking resistor can no longer absorb electrical energy in a metered manner due to the presence or expected occurrence of an unexpected short circuit at the semiconductor switch, this error usually leads to a large, destructive heat buildup at the braking resistor. This is associated with a corresponding risk to machines and personnel. After such a heat buildup, the braking resistor is usually destroyed and a new braking resistor is required, which is still very expensive even with this solution.

[0009] The braking resistor in the converter usually also serves as a precharging resistor to precharge the intermediate circuit capacitor at the DC voltage intermediate circuit in a metered manner so that the intermediate circuit capacitor is not damaged during the precharging process. Therefore, the protection of the braking resistor also serves to protect its function as a precharging resistor.

[0010] Since the braking resistor is an electrical load both in its function of electric braking and in its function as a pre-charging resistor, the term load resistor is introduced here, which is also used for the combined functions of braking resistor and pre-charging resistor. Summary of the invention

[0011] The object of the present invention is therefore to specify a protection device, a method for a protection device and a converter having the protection device, by means of which load resistors used as braking and precharging resistors during operation are better protected against damage or destruction than known solutions.

[0012] In order to achieve the above-mentioned purpose, a protection device for operating an electric motor at a converter is proposed, which includes a first and a second conductor of a DC voltage intermediate circuit, a switching device having a first and a second switch, an intermediate circuit capacitor, a load resistor as a precharging and braking resistor, a semiconductor switch and an electrical fuse for protecting the load resistor, wherein the electrical fuse and the first switch are electrically connected to the first conductor as a series circuit on the one hand, and are electrically connected to a first resistor interface of the load resistor and a first power supply interface of the semiconductor switch on the other hand, wherein the second switch is electrically connected to the first conductor on the one hand, and is electrically connected to a first capacitor interface of the intermediate circuit capacitor and a second resistor interface of the load resistor on the other hand, and wherein the semiconductor switch is electrically connected to the second conductor by means of a second power supply interface and the intermediate circuit capacitor is electrically connected to the second capacitor interface, respectively.

[0013] The use of a protective device is advantageous if the load resistor is provided for electrical braking, ie for converting the electrical energy generated by the generator drive into heat energy by means of semiconductor switches (brake chopper), and for precharging an intermediate circuit capacitor at the DC voltage intermediate circuit.

[0014] In fault-free generator-driven or motor-driven operation of the converter, the protective device is active. The electrical fuse is arranged as a protective element for the load resistor and the protective device is designed so that when an unexpected short circuit is detected at the semiconductor switch, the electrical fuse is triggered in a forced-actuated manner, wherein electrical energy can no longer flow through the load resistor and thus damage can be prevented.

[0015] As already mentioned, precharging of the intermediate circuit capacitor can also be achieved in an advantageously combined manner with the aid of a protective device, in particular with the aid of a load resistor of the protective device, wherein the protective device can also be activated in this operating state and, in the event of a failed semiconductor switch being identified, triggering of the electrical fuse can be achieved in a forced-drive manner.

[0016] In a first advantageous embodiment of the protection device, the first switch and the second switch form an alternating circuit and when the second switch is open, the first switch is subsequently closed, or when the second switch is closed, the first switch is subsequently opened.

[0017] In this case, it is advantageously ensured that, when the switches are actuated, both switches assume clearly defined switching states, wherein, in particular when the electrical fuse is tripped, the intermediate circuit capacitor is no longer supplied with electrical energy and can discharge.

[0018] In a further advantageous embodiment of the protection device, a control device is comprised, wherein the first switch and the second switch can be switched by means of a switching command which can be generated by the control device.

[0019] The control device advantageously takes over the safe actuation of the switch by means of the control command, wherein the control device can determine the presence or expected presence of an unexpected short circuit at the semiconductor switch and trigger the fuse to protect the load resistor by outputting a switching command to the switch.

[0020] In another advantageous embodiment of the protection device, a first temperature detection device is included which is arranged at the load resistor, wherein the resistance temperature of the load resistor can be detected by means of the first temperature detection device and transmitted to the control device as a first temperature signal.

[0021] The determined resistance temperature of the load resistor is advantageously a measure for whether the load resistor is still operable or whether the resistance temperature of the load resistor is too high for safe operation, wherein this information is provided to a control device by means of a first temperature signal in order to check for a possible or expected unexpected short circuit at the semiconductor switch.

[0022] In another advantageous embodiment of the protection device, a second temperature detection device is included which is arranged at the semiconductor switch, wherein the semiconductor temperature of the semiconductor switch can be detected by means of the second temperature detection device and transmitted to the control device as a second temperature signal.

[0023] The determined semiconductor temperature of the semiconductor switch can advantageously serve as a measure for whether the semiconductor switch is still operable or whether it constitutes a risk for the safe operation of the load resistor, wherein this information is provided to a control device by means of a second temperature signal for checking a possible or expected unexpected short circuit at the semiconductor switch.

[0024] In another advantageous design of the protection device, it includes a voltage detection device, which is electrically connected in series with the first power supply interface of the semiconductor switch or in series with the second power supply interface of the semiconductor switch, wherein the semiconductor output voltage of the semiconductor switch can be detected by means of the voltage detection device and transmitted to the control device as a voltage signal.

[0025] A determined semiconductor output voltage of a semiconductor switch (via a drain-source connection or a collector-emitter connection) can advantageously serve as a measure for whether the semiconductor switch is still operable or whether it constitutes a risk for the safe operation of a load resistor, wherein this information is provided to a control device by means of a voltage signal in order to check for a possible or expected unexpected short circuit at the semiconductor switch.

[0026] In another advantageous design of the protection device, it includes a current detection device, which is electrically connected between a first power supply interface of the semiconductor switch and a second resistance interface of the load resistor or between a second power supply interface of the semiconductor switch and a second conductor of the DC voltage intermediate circuit, wherein the semiconductor output current of the semiconductor switch can be detected by means of the current detection device and transmitted to the control device as a current signal.

[0027] A determined semiconductor output current of a semiconductor switch (in the drain-source path or the collector-emitter path) can advantageously serve as a measure for whether the semiconductor switch is still operable or whether it constitutes a risk for the safe operation of a load resistor, wherein this information is provided to a control device by means of a current signal for checking a possible or expected presence of an unexpected short circuit at the semiconductor switch.

[0028] In a further advantageous embodiment of the protection device, an actuation detection device is included, wherein actuation commands of a control interface for the semiconductor switch can be detected by means of the actuation detection device and transmitted as actuation signals to the control device.

[0029] The control command for the control interface (gate) of the semiconductor switch, i.e. the state of an off command or an on command at the semiconductor switch, can advantageously be used, in particular together with information about the semiconductor output voltage and / or together with information about the semiconductor output current, as a measure of whether the semiconductor switch is still operable or whether it constitutes a risk for the safe operation of the load resistor, wherein this information is provided to a control device by means of a control signal for checking a possible or expected presence of an unexpected short circuit at the semiconductor switch.

[0030] In order to achieve the above-mentioned purpose, a method for operating a protection device according to the present invention is also proposed, wherein, in fault-free generator-driven operation of the converter, when the electric motor is braked by means of a load resistor and a semiconductor switch, or in fault-free motor-driven operation of the converter, when the electric motor is driven by means of an intermediate circuit capacitor, a first switch of the switching device is opened and a second switch of the switching device is closed, wherein, in a test operation, the semiconductor switch is checked whether an unexpected short circuit exists or is expected, wherein, in a fault operation, if an unexpected short circuit of the semiconductor switch exists or is expected, the first switch is closed and the second switch is opened, and wherein, in a protection operation, an electrical fuse for protecting the load resistor is triggered.

[0031] Starting from a respectively fault-free generator-driven or motor-driven operation of the converter, wherein the first switch is open and the second switch is closed, the test operation is carried out in an advantageous form of the method in parallel with the fault-free generator-driven or motor-driven operation. The presence or expected presence of an unexpected short circuit leads to an erroneous operation. The expected presence of an unexpected short circuit means that this unexpected short circuit is about to occur if the generator-driven or motor-driven operation continues.

[0032] In fault operation, the switches are switched as an active action, wherein in protection operation, due to the closing of the first switch and the opening of the second switch, an electrical fuse for protecting the load resistor is triggered and a safe operating state is established for the converter by means of the protection device.

[0033] In a first advantageous embodiment of the method, in the event of an unexpectedly occurring short circuit, or in the event of an expected short circuit, the switch is switched by means of a switching command from the control device and a triggering signal is generated for triggering the electrical fuse.

[0034] In a further advantageous embodiment of the method, the presence or expected presence of an unexpected short circuit is determined by the control device based on the resistance temperature of the load resistor.

[0035] The resistance temperature of the load resistor is a measure for whether the load resistor is still operable or whether the resistance temperature is too high for safe operation of the load resistor. The control device can therefore advantageously determine the presence or expected presence of an unexpected short circuit using the resistance temperature and whether the protection of the load resistor must be activated using an electrical fuse.

[0036] In a further advantageous embodiment of the method, the presence or expected presence of an unexpectedly occurring short circuit is determined by the control device based on the semiconductor temperature of the semiconductor switch.

[0037] The semiconductor temperature of the semiconductor switch is a measure of whether the semiconductor switch is still operable or poses a risk to the safe operation of the load resistor. The control device can therefore advantageously determine the presence or expected presence of an unexpected short circuit using the semiconductor temperature and whether the protection of the load resistor must be activated using an electrical fuse.

[0038] In a further advantageous embodiment of the method, the presence or expected presence of an unexpectedly occurring short circuit is determined by the control device based on a control command of a control interface for the semiconductor switch and a semiconductor output voltage of the semiconductor switch.

[0039] The semiconductor output voltage of the semiconductor switch is a measure of whether the semiconductor switch is still operable or poses a risk to the safe operation of the load resistor. The control device therefore advantageously determines the presence or expected presence of an unexpected short circuit and whether the protection of the load resistor must be activated by means of an electrical fuse, using the semiconductor output voltage and the control command of the control interface for the semiconductor switch.

[0040] In a further advantageous embodiment of the method, the presence or expected presence of an unexpectedly occurring short circuit is determined by the control device based on a control command of a control interface for the semiconductor switch and a semiconductor output current of the semiconductor switch.

[0041] The semiconductor output current of the semiconductor switch is a measure for whether the semiconductor switch is still operable or poses a risk to the safe operation of the load resistor. The control device therefore advantageously determines the presence or expected presence of an unexpected short circuit and whether the protection of the load resistor must be activated by means of an electrical fuse, using the semiconductor output current and the control command of the control interface for the semiconductor switch.

[0042] In order to achieve the purpose, a converter having a protection device according to the invention is also proposed, wherein the protection device can be operated using the method according to the invention, wherein an electric motor can be operated at a power grid with the aid of the converter, and wherein, in protection operation, the generator-driven or motor-driven operation of the converter and the precharging of the intermediate circuit capacitor of the converter can be blocked with the aid of the protection device after triggering the electrical fuse. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above characteristics, features and advantages of the present invention and the methods for achieving them will become clearer and easier to understand in conjunction with the following description of the embodiments, which are described in detail in conjunction with the accompanying drawings. The drawings show:

[0044] Figure 1 A first schematic diagram of a protection device according to the present invention is shown,

[0045] Figure 2 Shown according to Figure 1 A second schematic diagram of a protection device with a control device,

[0046] Figure 3 shows the method for running according to Figure 1 or Figure 2 A structural diagram of the method of protecting the device, and

[0047] Figure 4 A schematic diagram of a converter with a protective device and a method for a protective device is shown, wherein an electrical machine can be operated on a power supply network by means of the converter. DETAILED DESCRIPTION

[0048] Figure 1 A first schematic diagram of a protection device 1 according to the invention is shown.

[0049] The DC voltage intermediate circuit 2 has a first conductor 4 and a second conductor 5 .

[0050] The electrical fuse 12 and the first switch 7 of the switching device 6 are electrically connected as a series circuit on the one hand to the first conductor 4 and on the other hand to the first resistor connection 13 of the load resistor 10 and the first power supply connection 14 of the semiconductor switch 11 .

[0051] The second switch 8 is electrically connected on the one hand to the first conductor 4 and on the other hand to a first capacitor connection 15 of the intermediate circuit capacitor 9 and to a second resistor connection 16 of the load resistor 10 .

[0052] The semiconductor switch 11 is electrically connected to the second conductor 5 by means of a second power supply connection 17 , and the intermediate circuit capacitor 9 is electrically connected to the second conductor 5 by means of a second capacitor connection 18 .

[0053] In order to precharge the intermediate circuit capacitor 9, Figure 1 As shown, the first switch 7 of the switching device 6 is closed and the second switch 8 of the switching device 6 is open. The intermediate circuit capacitor 9 is precharged via the DC voltage intermediate circuit 2, the first conductor 4, the closed first switch 7, the electrical fuse 12, the load resistor 10, the intermediate circuit capacitor 9 and the second conductor 5.

[0054] In the case of generator-driven or motor-driven operation of the protection device 1, the first switch 7 of the switching device 6 is opened and the second switch 8 of the switching device 6 is closed ( Figure 1 In generator-driven operation, electrical energy from the DC voltage intermediate circuit 2 can be supplied via the first conductor 4, the closed second switch 8 ( Figure 1 ), the load resistor 10, the semiconductor switch 11 and the second conductor 5 are converted into thermal energy by means of the load resistor 10 and the semiconductor switch 11 at the load resistor 10.

[0055] In generator-driven operation, electrical energy can also be fed into the intermediate circuit capacitor 9, as long as its charge capacity still permits this, via the first conductor 4, the closed second switch 8 ( Figure 1 ), the intermediate circuit capacitor 9 to be charged and the second conductor 5 (the closed switching state is not shown).

[0056] The motor-driven operation of the protection device 1 is also activated by closing the second switch 8 ( Figure 1 The intermediate circuit capacitor 9 which is electrically connected to the DC voltage intermediate circuit 2 thus ensures in particular that the level of the DC voltage is as constant as possible and is smoothed.

[0057] Figure 2 Shown according to Figure 1 A second schematic diagram of the protection device 1.

[0058] The control device 19 can generate a control command 20 , by means of which the first switch 7 and the second switch 8 of the switching device 6 can be switched.

[0059] The resistance temperature 22 of the load resistor 10 can be detected by means of the first temperature detection device 21 and can be transmitted to the control device as a first temperature signal.

[0060] The semiconductor temperature 24 of the semiconductor switch 11 can be detected by means of the second temperature detection device 23 and can be transmitted to the control device as a second temperature signal.

[0061] The semiconductor output voltage 26 of the semiconductor switch 11 can be detected by means of a voltage detection device 25 connected to the first and second power supply connections 14 , 17 of the semiconductor switch 11 and can be transmitted to the control device as a voltage signal.

[0062] With the aid of a current detection device 27 , the semiconductor output voltage 26 of the semiconductor switch 11 can be detected and transmitted as a voltage signal to a control device. The current detection device is electrically connected in series with the first power supply connection 14 of the semiconductor switch 11 between the first power supply connection 14 of the semiconductor switch 11 and the second conductor 5 .

[0063] Figure 3 shows the method for running according to Figure 1 or Figure 2 A structural diagram of a method 42 of protecting a device 1 .

[0064] In fault-free generator-driven operation 37 of the converter, when the electric motor is braked by means of a load resistor and semiconductor switches, or in fault-free motor-driven operation 38 of the converter, when the electric motor is driven by means of an intermediate circuit capacitor, the first switch 7 of the switching device 6 is opened and the second switch 8 of the switching device 6 is closed.

[0065] In the test operation 39 , the semiconductor switch 11 is checked in the generator-driven operation 37 and in the motor-driven operation 38 whether an unexpected short circuit 41 is present 40 or is expected to be present 29 .

[0066] In fault operation 35 , in the presence 40 or expected presence 29 of an unexpectedly occurring short circuit 41 of the semiconductor switch 11 , the first switch 7 is closed and the second switch 8 is open.

[0067] In protection mode 36 , electrical fuse 12 is triggered to protect the load resistor.

[0068] In the event of an unexpected short circuit 41 which occurs 40 or is expected to occur 29, switches 7, 8 are switched by means of a switching command from control device 19. A triggering signal 43 for triggering electrical fuse 7 is generated by control device 19.

[0069] Figure 4 A schematic diagram of a converter 3 with a protection device 1 and a method 42 for protecting the protection device 1 is shown.

[0070] The electric machine 33 can be operated on a power supply network 34 by means of a converter 3. The electrical connection between the converter and the power supply network 34 and the electric machine 33 is shown here by way of example with the aid of a three-phase conductor system.

[0071] In protection mode 36 , generator-driven or motor-driven operation 37 , 38 of the converter 3 and precharging of the intermediate circuit capacitors of the converter can be interrupted by means of the protection device 1 after the electrical fuse 12 has been triggered.

Claims

1. A protection device (1) for operating an electric machine (33) at a converter (3), the protection device comprising: - a first conductor (4) and a second conductor (5) of a DC voltage intermediate circuit (2), - a switching device (6) having a first switch (7) and a second switch (8), - an intermediate circuit capacitor (9), - load resistor (10) as pre-charging resistor and braking resistor, - a semiconductor switch (11) and - an electrical fuse (12) for protecting the load resistor (10), wherein: the electrical fuse (12) and the first switch (7) are electrically connected as a series circuit to the first conductor (4) on the one hand and to the first resistance connection (13) of the load resistor (10) and to the first power connection (14) of the semiconductor switch (11) on the other hand, the second switch (8) is electrically connected on the one hand to the first conductor (4) and on the other hand to a first capacitor connection (15) of the intermediate circuit capacitor (9) and a second resistor connection (16) of the load resistor (10), and The semiconductor switch (11) is electrically connected to the second conductor (5) by means of a second power supply connection (17) and the intermediate circuit capacitor (9) is electrically connected to the second conductor (5) by means of a second capacitor connection (18).

2. The protection device (1) according to claim 1, wherein: The first switch (7) and the second switch (8) form an alternating circuit, and wherein, when the second switch (8) is open, the first switch (7) is subsequently closed, or when the second switch (8) is closed, the first switch (7) is subsequently opened.

3. The protection device (1) according to claim 1 or 2, comprising a control device (19), wherein: The first switch (7) and the second switch (8) can be switched by means of a control command (20) which can be generated by the control device (19).

4. The protection device (1) according to claim 3, comprising a first temperature detection device (21) arranged at the load resistor (10), wherein: The resistance temperature (22) of the load resistor (10) can be detected by means of the first temperature detection device (21), and the resistance temperature can be transmitted to the control device (19) as a first temperature signal.

5. The protection device (1) according to claim 3, comprising a second temperature detection device (23) arranged at the semiconductor switch (11), wherein: The semiconductor temperature (24) of the semiconductor switch (11) can be detected by means of the second temperature detection device (23) and the semiconductor temperature can be transmitted to the control device (19) as a second temperature signal.

6. The protection device (1) according to claim 3, comprising a voltage detection device (25), wherein the voltage detection device is electrically connected to the first power interface (14) and the second power interface (17) of the semiconductor switch (11), wherein: A semiconductor output voltage (26) of the semiconductor switch (11) can be detected by means of the voltage detection device (25) and the semiconductor output voltage can be transmitted to the control device (19) as a voltage signal.

7. The protection device (1) according to claim 3, comprising a current detection device (27), wherein the current detection device is electrically connected in series with the first power interface (14) of the semiconductor switch (11) or is electrically connected in series with the second power interface (17) of the semiconductor switch (11), wherein: The semiconductor output current of the semiconductor switch (11) can be detected by means of the current detection device (27) and the semiconductor output current can be transmitted to the control device (19) as a current signal.

8. The protection device (1) according to claim 3, comprising a drive control detection device, wherein: A control command for a control interface of the semiconductor switch (11) can be detected by means of the control detection device and the control command can be transmitted to the control device (19) as a control signal.

9. A method (42) for operating a protection device (1) according to any one of claims 1 to 8, wherein - in fault-free generator-driven operation of the converter (3), the electric machine (33) is braked by means of the load resistor (10) and the semiconductor switch (11), or in fault-free motor-driven operation of the converter (3), the electric machine (33) is driven by means of the intermediate circuit capacitor (9), the first switch (7) of the switching device (6) is opened and the second switch (8) of the switching device (6) is closed, - in a test run (39), checking the semiconductor switch (11) for the presence (40) or expected presence (29) of an unexpected short circuit (41), - in the event of an unexpected short circuit (41) of the semiconductor switch (11) occurring (40) or expected to occur (29) during fault operation (35), the first switch (7) is closed and the second switch (8) is opened, and In the protection mode (36), an electrical fuse for protecting the load resistor (10) is triggered.

10. The method (42) of claim 9, wherein: In the event of the presence (40) or expected presence (29) of the unexpectedly occurring short circuit (41), the control device (19) switches the first switch (7) and the second switch (8) by means of a switching command and generates a triggering signal (43) for triggering the electrical fuse.

11. The method (42) of claim 9, wherein: The presence (40) or expected presence (29) of the unexpectedly occurring short circuit (41) is determined by a control device (19) based on the resistance temperature (22) of the load resistor (10).

12. The method (42) of claim 9, wherein: The presence (40) or expected presence (29) of the unexpectedly occurring short circuit (41) is determined by a control device (19) based on a semiconductor temperature (24) of the semiconductor switch (11).

13. The method (42) of claim 9, wherein: The presence (40) or expected presence (29) of the unexpectedly occurring short circuit (41) is determined by a control device (19) based on a control command of a control interface for the semiconductor switch (11) and a semiconductor output voltage (26) of the semiconductor switch (11).

14. The method (42) of claim 9, wherein: The presence (40) or expected presence (29) of the unexpectedly occurring short circuit (41) is determined by a control device (19) based on a control command of a control interface for the semiconductor switch (11) and a semiconductor output current of the semiconductor switch (11).

15. A converter (3) having a protection device (1) according to any one of claims 1 to 8, wherein: The protection device (1) can be operated using a method (42) according to any one of claims 9 to 13, wherein an electric motor (33) can be operated at a power grid (34) with the aid of the converter (3), and wherein, in a protection operation (36), generator-driven or motor-driven operation of the converter (3) and precharging of an intermediate circuit capacitor (9) of the converter (3) can be interrupted with the aid of the protection device (1) after triggering an electrical fuse (12).

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