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Unformatted text preview: ad/s] , determine the resultant armature current and
is constant with speed). 2
Problem 3: Given a 24VDC PM motor with ra = 0.2279Ω and Kv = 0.1253V·s,
a. Sketch the electromagnetic torque versus speed (ω on the x-axis) characteristic. Calculate the y-intercept, x-intercept, and slope. (y-int = 13.1953 Nm, x-int = 191.5
rad/s, slope = -0.0689)
b. If and TLoss is negligible, what is the steady-state operating speed and the armature current?
[ω = 130.1 rad/s, Ia = 33.78A]
c. What is the efficiency at this operating point?
[η = 67.9%]
Problem 4: We wish to reduce the speed of the motor above to half its current value by
adjusting the armature voltage.
a. Find the load torque at this speed. (1.056 Nm)
b. Find the new armature current. (8.43 A)
c. Find the required armature voltage. (1...
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- Fall '08