The data sheet for a 350-W permanent-magnet dc motor provides the following parameters:

Rated voltage: V_rated = 24 V, Armature resistance: R_a = 97 m?, No-load speed: n_nl = 3580 r/min, No-load current: I_{a, nl} = 0.47 A

a. Calculate the motor torque-constant K_m in V/ (rad/sec).

b. Calculate the no-load rotational loss.

c. The motor is supplied from a 30-V dc supply through a PWM inverter. Table gives the measured motor current as a function of the PWM duty cycle D. Complete the table by calculating the motor speed and the load power for each value of D. Assume that the rotational losses vary as the square of the motor speed.

Transcribed Image Text:

D 1, (A) r/min Pinad (W) 13.35 12.70 12.05 11.40 0.80 0.75 0.70 0.65 0.60 0.55 10.70 10.05 9.30 0.50