A brushless direct current motor drive without rotor position sensors

A drive which enables sensorless operation of brushless direct current motors with trapezoidal flux distributions is proposed. The proposed drive improves upon an older version but is implemented using different hardware and a microcontroller for greater flexibility. The microcontroller allows easy implementation of more sophisticated control schemes which result in extending the speed range of the motor. Experimental results show that the proposed operating scheme without modification allows the motor to be operated at speeds as low as 55 rpm and higher than 2500 rpm with reasonable dynamic performance. More sophisticated control schemes can only improve these results.