Robert Boschgmbh

Robret Bosch Gmbh

Andreas Koenig

Tino Merkel

Lingling Xie

Guenther Plapp

Marc Rudolph

The invention results in improved switching from the idling mode to an active short circuit mode of an electric machine. According to the invention, the switch from the idling mode to the active electric short circuit mode is delayed until predefined voltage conditions have been reached on the external terminals of an electric machine or until the rotor of the electric machine is in a predetermined position corresponding to the required voltage conditions.

Device and method for operating an electric machine

The present invention provides a device and a method for changing over an electric machine from the regular operating mode into the open-circuit mode. In order to avoid excessive increases in voltage and associated adverse effects on the electric machine and the other components, in particular batteries, a further control phase is introduced between the end of the regular operating mode and the freewheeling mode, during which further control phase the voltage at the terminals of the electric machine is continuously adjusted from the voltage previously set in the regular operating mode to the expected open-circuit voltage of the electric machine.

The present invention provides a method and a device for operating an electric machine for a soft changeover from a normal or free-wheel mode to an active short-circuit. To this end, a voltage with which the electric machine is actuated is first reduced in a defined manner to a predefined, preferably very low value and then the phase connections of the electric machine are short-circuited. Excessively high overcurrents, particularly overcurrents greater than the nominal current of the electric machine, can thus be avoided.

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Ostfildern, Germany

Andreas Koenig