Monitoring device and method for monitoring a closed state of a battery switch, inverter device, electric axle drive and motor vehicle

1 . A monitoring device for monitoring an on/off state of a battery switch, wherein the battery switch has a first terminal for connecting the battery switch to a pole on a battery, and a second terminal for connecting the battery switch to a pole on an intermediate circuit, wherein the monitoring device comprises:

a series circuit with a power source and a diode, wherein the series circuit is connected in parallel to the battery switch;

the power source, which has a first terminal and a second terminal, wherein the power source is configured to generate a current or voltage between the first terminal and the second terminal of the battery switch;

the diode, which has a first terminal and a second terminal, wherein the first terminal of the diode is connected to the second terminal of the power source; and

an evaluation circuit configured to create an evaluation signal based on a voltage at the first terminal of the diode, which indicates the on/off state of the battery switch,

wherein the evaluation circuit comprises a comparator, wherein the comparator has a first input, a second input, and an output, wherein the comparator is connected by the first input to the first terminal of the diode, and by the second input to a reference voltage terminal, wherein the comparator is configured to provide the evaluation signal at the output.

2 . The monitoring device according to claim 1 ,

wherein the diode has a cathode and an anode, wherein the first terminal of the diode is the anode, and the second terminal of the diode is the cathode.

3 . The monitoring device according to claim 1 ,

wherein the first terminal of the power source is connected to the second terminal of the battery switch, and

wherein the second terminal of the diode is connected to the first terminal of the battery switch.

4 . The monitoring device according to claim 1 ,

wherein the first terminal of the power source is connected to the first terminal of the battery switch, and

wherein the second terminal of the diode is connected to the second terminal of the battery switch.

5 . The monitoring device according to claim 1 ,

wherein the power source is a current source.

6 . The monitoring device according to claim 1 ,

wherein the power source is a voltage source.

7 . The monitoring device according to claim 1 ,

wherein the power source comprises a first resistor, a second resistor, and a supply voltage collector,

wherein the first resistor is between the supply voltage collector and the second terminal of the power source, and

wherein the second resistor is between the first terminal of the power source and the second terminal of the power source.

8 . The monitoring device according to claim 7 ,

wherein the series circuit comprises a third resistor.

9 . The monitoring device according to claim 8 ,

wherein the diode is between the third resistor and the power source.

10 . The monitoring device according to claim 1 , comprising:

the battery switch comprising the first terminal for connecting the battery switch to the pole on the battery, and the second terminal for connecting the battery switch to the pole on the intermediate circuit.

11 . An inverter device comprising:

the monitoring device according to claim 10 , which has the intermediate circuit; and

an inverter configured to convert battery voltage to drive voltage,

wherein the intermediate circuit is between the battery switch and the inverter.

12 . An electric axle drive for a motor vehicle comprising:

at least one electric machine;

a transmission; and

the inverter device according to claim 11 .

13 . A motor vehicle comprising:

the inverter device according to claim 11 .

14 . A method of monitoring an on/off state of a battery switch,

wherein the battery switch has a first terminal for connecting the switch to a pole on a battery, and a second terminal for connecting the switch to a pole on an intermediate circuit, wherein the method is executed with a series circuit that contains a power source and a diode, and with an evaluation circuit, wherein the series circuit is connected in parallel to the battery switch, wherein the power source has a first terminal and a second terminal, wherein the diode has a first terminal and a second terminal, wherein the first terminal of the diode is connected to the second terminal of the power source, and the method comprising:

generating a current or voltage between the first terminal of the battery switch and the second terminal of the battery switch with the power source; and

providing an evaluation signal indicating the on/off state of the battery switch by the evaluation circuit based on a voltage at the first terminal of the diode,

wherein the evaluation circuit comprises a comparator, wherein the comparator has a first input, a second input, and an output, wherein the comparator is connected by the first input to the first terminal of the diode, and by the second input to a reference voltage terminal, the method comprising:

providing the evaluation signal by the comparator at the output of the comparator.