DE 10 2010 000 852 A1, which is incorporated by reference, discloses a method for locating a defective switch and for determining the nature of the defect. The previously known method detects whether the defective switch is defectively switched on or switched off.
Inverters for actuating brushless motors generally consist of six switches. After a defect, each switch can have in principle two different characteristics: switched off, that is to say blocked in the open switch position, or switched on, that is to say blocked in the closed switch position. A defectively switched-on switch is also commonly referred to as a short circuit. A defectively switched-on switch causes a torque in the electric motor counter to the direction of operation of the electric motor. In particular in safety-relevant applications, it is then important to continue to operate the electric motor in an emergency mode.