Help Finding voltage at steady state?

Thread Starter


Joined 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?


Joined 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 = ?