Han, "Torque ripple reduction in BLDC torque motor with nonideal
back EMF," IEEE Transactions on Power Electronics, vol.
Stable operation and control of BLDC motor (with trapezoidal
back EMF profile) necessitate the current commutation in windings to be synchronized with instantaneous rotor position.
3) Sensing of the third harmonic of the
back EMF. 4) Detecting the freewheeling diode conduction and related extended strategies.
Klasnic, "Stationary Frame Induction Motor Feed Forward Current Controller With
Back EMF Compensation," Energy Conversion, IEEE Transactions, vol.
Reed relays contain a reed switch, a coil for creating a magnetic field, an optional diode for handling
back EMF from the coil, and an encapsulating package with connection terminals.
But in low speed region and flux weakening region, the estimated values of the currents and
back EMF cannot help as they have large ripples.
To reduce THD of
back EMF, fractional slot shorted pitch distribution windings are used in [10, 11].
11 gives the calculated
back EMF waveforms (Phase-A) when rotor rotating at 150 rpm, which demonstrated that electric power can be generated by the electromagnetic coupling between the PMs and both windings.
Thus, this algorithm adds sensorless control algorithms based on the observation of
back emf.