Practical issues and research opportunities when implementing zero speed sensorless control

It is well accepted that drives require knowledge of rotor and flux linkage positions to precisely control torque and motion at all speeds including zero and near zero. In industrial applications the rotor position sensor is the standard solution. However, in the rapidly emerging automotive and aerospace applications the harsh environment (temperature, humidity, chemicals and vibration) can easily cause failure of the sensor connectors, cables or sensor components. Such failures are unacceptable. Furthermore, the weight and cost penalty associated with mechanically protecting the sensor, sensor connector, and sensor cabling is a significant disadvantage. Thus, true sensorless operation through the power leads is fast becoming a requirement. This paper will focus on practical Implementation and research issues for sensorless, high performance, zero and near zero speed, motion control.