Brushless rotor position estimation

Discussion in 'General Electronics Chat' started by hubble, Jan 12, 2016.

  1. hubble

    Thread Starter Member

    Jun 17, 2009
    How to estimate rotor position of a three phase brushless dc motor having trapezoidal shaped air gap flux distribution using flux-linkage based technique? The commonly used equation given in books and other technical resources to estimate the flux is given as Ψ = Ψp + Ψpm = ∫(U - Ri)dt , where Ψ denotes total flux linkage of the phase (consisting of self and mutual flux Ψp; and Ψpm due to permanent magnet rotor), U denotes phase voltage; R and i denote phase resistance and current. But how does this relation translate into rotor position? What electrical quantity do we actually measure to control the motor in this method?

    Thank you.
    Last edited: Jan 13, 2016