Help Finding voltage at steady state?

Discussion in 'Homework Help' started by cobra1, Apr 7, 2009.

  1. cobra1

    Thread Starter New Member

    Apr 7, 2009
    A PMDC with a torque constant load torque of
    Km= 0.2 NM/A is modeled as the below circuit. If the load is TL = 2 NM at a speed of wm=326 rad/s and the armature resistance is Ra=1 W,
    find the applied motor terminal voltage Vab at steady-state.


    Can anyone here help me with this?
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    Try this approach.

    Assuming no mechanical losses then

    Electrical torque, Te = Mechanical torque = 2Nm

    So Electrical Power at motor back emf

    Pe = ω x Te = ? watts

    Te = Km x ia

    hence with Km and Te known

    ia = ?

    Motor emf, E = Pe/ia [at steady state!]

    Applied Vab = E+ia x Ra = ?