Speed sensorless control of a DC-motor via adaptive filters

In the motor control industry, digital signal processor (DSP) systems offer major improvements compared to analogue designs, notably enabling to replace speed or position sensors by the implementation of sensorless control algorithms. A new viable method that estimates the rotor velocity of a permanent magnet DC-motor from the ‘rotor slot harmonics’ present in the DC current signal is proposed. This approach is based on both two adaptive digital filters and a frequency estimator, which is fitted to this particular application and compared to a classical technique. Finally, an algorithm that selects the best speed estimation to reach high-speed transient behaviour and to obtain speed estimation error equal to zero at steady state is proposed.