Electromechanical energy conversion

Discussion in 'Homework Help' started by Sarilaci, Dec 16, 2015.

  1. Sarilaci

    Thread Starter New Member

    Dec 16, 2015
    1-electromagnet with a relative permeability of 1000 and a uniform thickness of
    10 cm has the dimensions as given in Figure . Calculate the limit value of the current in the
    series-connected coils so that the electromagnet can lift the ferromagnetic bar having a relative
    permeability of 300 and a mass of 20 kg (Earth’s gravitational constant g=9.81 m/s2).


    Consider the two-coil rotating electromechanical system shown in Figure. The
    airgap is uniform and the iron core is infinitely permeable. The self inductance of the rotor and
    stator coils are Lr = Ls = 0.6 H, and the mutual inductance between them varies with the angular
    position (θ) as: Lrs(θ) = Lsr(θ) = 0.5 cos θ, where θ is in degrees.


    a) Calculate the torque induced on the rotor when θ = 30o, Is = 5 A and Ir = 2 A, where Is
    and Ir are currents in stator and rotor coils, respectively.

    b) The rotor coil is open circuited and the stator coil current is fixed to 5 A. Calculate
    induced voltage between the terminals of the rotor coil when the rotor is revolving at an
    angular speed of 100 rad/s.
  2. crutschow


    Mar 14, 2008
    So how's it going so far with your solution to the questions?
    Or are you expecting us to do your homework? :rolleyes:
  3. Sarilaci

    Thread Starter New Member

    Dec 16, 2015
    I have same examples with solutions but in this questions,electromagnet and ferromagnetic bar have infinite permeability.How do we solve that permeabilities are different as question 1.

    In question 2b, I try to solve this question by using this formula: e2=Lr(Q)*di2/dt + i2*wm*dLr(Q)/dQ + Ls(Q)*di1/dt + i1*wm*Ls(Q)/dQ

    I find -250sinQ, is it true?