Estimate the minimum dc input voltage to the switch-mode converter required to supply the motor in Problem 15-1 if the maximum speed is 5000 rpm and the torque is 0.25 N-m.

Problem 15-1

A brushless, permanent-magnet, four-pole, three-phase motor has the following parameters:

The above motor produces a trapezoidal back-emf. The torque constant is obtained as a ratio of the maximum torque produced to the current flowing through two of the phases. The voltage constant is the ratio of the peak phase-to-phase voltage to the rotational speed. If the motor is operating at a speed of 3000 rpm and delivering a torque of 0.25 N-m, plot the idealized phase current waveforms.