Digital realisation of sensorless drive: some practical considerations

This paper describes some real time filtering issues in the realisation of sensorless control. Though many sensorless control algorithms have now been proposed in the literature, fewer complete closed loop implementations have been reported. Part of the reason is that the step of closing the control loop with estimated variables imposes strong demands on the quality of the estimates. This paper describes two filtering solutions with low computational cost requirements. The solutions are compared on an experimental setup using the authors' algorithm for position estimation in a permanent magnet synchronous motor.