Method for switching an operating state of an electric machine and device for switching an operating state of an electric machine

A device for switching from a freewheeling operating state of an electric machine comprising three phase terminals to a short-circuit operating state, the device comprising:

• a first switching element, which is designed to electrically connect a first phase terminal of the electric machine to a node, wherein the first switching element comprises a first freewheeling diode;
• a second switching element, which is designed to electrically connect a second phase terminal of the electric machine to the node, wherein the second switching element comprises a second freewheeling diode;
• a third switching element, which is designed to electrically connect a third phase terminal of the electric machine to the node, wherein the third switching element comprises a third freewheeling diode;
• a drive device, which is configured to receive a request for switching the operating state of the electric machine to the short-circuit operating state, and to output control signals for closing the third switching element and the second switching element at least partly successively at points in time predefined depending on a drive parameter of the electric machine, or closing the second switching element simultaneously with the third switching element, to
• transition from the freewheeling operating state to a partial-phase short circuit operating state having only two phase terminals conductively connected to one another, and the drive device is configured to output control signals for closing the first switching element at a point in time predefined depending on the drive parameter of the electric machine to transition from the partial-phase short-circuit operating state to the short circuit operating state having all three phase terminals conductively connected to each other,
• wherein the drive parameter of the electric machine is a value or a profile of an electrical voltage of the electric machine or a rotor angle of the rotor of the electric machine or another parameter on the basis of which a value or a profile of an electrical voltage of the electric machine or the rotor angle of the rotor of the electric machine can be deduced.

A device for switching from a freewheeling operating state of an electric machine comprising three phase terminals to a short-circuit operating state, the device comprising:

• a first switching element configured to electrically connect a first phase terminal of the electric machine to a node, wherein the first switching element includes a first freewheeling diode;
• a second switching element configured to electrically connect a second phase terminal of the electric machine to the node, wherein the second switching element includes a second freewheeling diode;
• a third switching element configured to electrically connect a third phase terminal of the electric machine to the node, wherein the third switching element includes a third freewheeling diode;
• and
• a drive device configured to receive a request for switching the operating state of the electric machine to the short-circuit operating state, and to output control signals for closing the third switching element and the second switching element at least partly successively at points in time predefined depending on a drive parameter of the electric machine, or closing the second switching element simultaneously with the third switching element, to
• transition the electrical machine from the freewheeling operating state to a partial-phase short circuit operating state having only two phase terminals conductively connected to one another, and closing the first switching element at a point in time predefined depending on the drive parameter of the electric machine to transition from the partial-phase short circuit operating state to the short circuit operating state having all three phase terminals conductively connected to each other,
• wherein the drive parameter of the electric machine is a value or a profile of an electrical voltage of the electric machine or a rotor angle of the rotor of the electric machine or another parameter on the basis of which a value or a profile of an electrical voltage of the electric machine or the rotor angle of the rotor of the electric machine can be deduced.