1. A method ( 30 ) for actuating an electric machine ( 14 ) in the motor starting mode by a power electronic system ( 10 ) having a multiplicity of controllable power switches which are designed to supply the electric machine ( 14 ) with electric current (l_s), the method comprising: estimating ( 38 ), by a controller, a total amount of energy ( 50 ) which is required to reach a predefined rotational speed (n_crit) and a time period (t_ 0 ) for reaching the predefined rotational speed (n_crit); determining ( 42 ), by the controller, a setpoint torque (M) for starting the electric machine ( 14 ) on the basis of the estimated total amount of energy ( 50 ) and the estimated time (t_ 0 ) such that a maximum permissible energy loss is not reached prior to the electric machine ( 14 ) reaching the predefined rotational speed (n_crit); and actuating ( 46 ), by the controller, the power electronic system ( 10 ) in accordance with the lesser of a maximum permissible torque M max and the setpoint torque (M).