On-lime extraction of the rotational back EMF of surface-mounted permanent magnet brushless
motors (PMBM) with a reasonable degree of accuracy offers a possibility for using simple digital
filtering to realize high performance sensorless control of such motors. Such possibility is
investigated theoretically and experimentally in the work reported in this paper. Although the
principle is applicable to both two PMBM motor types i.e. those with sinusoidal or trapezoidal
back EMF, the sinusoidal type is selected as a representative case. Both simulation and
experimental results ensure the effectiveness of the proposed technique.