Active short circuit
An active short circuit (AKS) is a measure in drive technology that is used to avoid damage when electrical voltages are too high . The targeted AKS is considered to be a safe mode for the prime movers. For this purpose, the connection lines for the motors , which are mostly operated with three-phase current , are short-circuited in the electrical machine by IGB transistors of the power electronics .
The active short circuit is regarded as a safe condition in vehicles with an electrified drive concept. A major advantage is the absence of voltage in the system in operating situations such as maintenance or crashes. This is particularly advantageous with permanent synchronous machines, as these can induce life-threatening voltages at high speeds. In order to be able to operate a permanent synchronous machine without overheating in an active short circuit, long-term winding concepts (= high induced voltage) are not advisable. With unsuitable converter / machine concepts, this operating state leads to almost immediate thermal damage.