Patent ID: 8213140

Claim:
An apparatus for the operation of an electrical machine ( 1 ) for driving a motor vehicle including a drive system ( 25 ) with an output stage ( 2 ) having three upper circuit breakers ( 2 o 1 , 2 o 2 , 2 o 3 ) and three lower circuit breakers ( 2 u 1 , 2 u 2 , 2 u 3 ), the electrical machine ( 1 ) being switchable off by the drive system ( 25 ) and including an external controller ( 30 ) for controlling the switching of the electrical machine ( 1 ) to an off state, wherein a bidirectional communication capability is provided between the external controller ( 30 ) and the drive system ( 25 ) of the electrical machine ( 1 ) and wherein a separate switch-off line ( 34 ) is provided extending between the external controller ( 30 ) and the drive system ( 25 ) for fast transmission of a switch-off signal from the external controller ( 30 ) to the drive system ( 25 ) of the electrical machine ( 1 ), wherein, for switching off the electrical machine ( 1 ), the output stage ( 2 ) is subjected to a three-phase short circuit by shorting one of the three upper circuit breakers ( 2 o 2 , 2 o 2 , 2 o 3 ) and the three lower circuit breakers ( 2 u 1 , 2 u 2 , 2 u 3 ) when the rotation seed D 1 does not fall below a definable limit value GR 1 or a voltage U DC of the output stage ( 2 ) exceeds a limit value U max ; and all the circuit breakers ( 2 o 2 , 2 o 2 , 2 o 3 , 2 u 1 , 2 u 2 , 2 u 3 ) of the output stage ( 2 ) are opened for switching off the electrical machine ( 1 ), when the rotation speed D 1 is below the limit value GR 1 and the voltage U DC of the output stage ( 2 ) does not exceed a limit value U max .