High resolution optical encoders are used in industrial servo drives with position and/or speed control for providing the respective feedback signals. In applica- tions with lower accuracy requirements resolvers are used as feedback sensors with respect to lower cost. As a resolver is nothing else than an electrical AC machine of special design, there is the basic idea to operate the servo motor itself like a resolver – in parallel to its original drive operation, of course. High frequency resolver sig- nals are injected to the servo motor without disturbing its original purpose (i. e. the production of torque). The reaction of the servo motor on the high frequency signals can be detected by the current sensors, which are availa- ble with respect to the current control loop anyway. A lot of schemes and concepts for encoderless AC drive control providing good operation during standstill are already published. Acceptance by industry, however, is not very extended. The main reasons for hesitations in industry are