The three-phase 6/4 VRM of Problem 8.4 has a winding resistance of 0.15/phase and a leakage inductance

The three-phase 6/4 VRM of Problem 8.4 has a winding resistance of 0.15Ω/phase and a leakage inductance of 4.5 mH in each phase. Assume that the rotor is rotating at a constant angular velocity of 1750 r/min.

a. Plot the phase-1 inductance as a function of the rotor angle θm.

b. A voltage of 75 V is applied to phase 1 as the rotor reaches the position θm = -30° and is maintained constant until θm = 0°. Calculate and plot the phase-1 current as a function of time during this period.

c. When the rotor reaches θm = 0°, the applied voltage is reversed so that a voltage of-75 V is applied to the winding. This voltage is maintained until the winding current reaches zero, at which point the winding is open-circuited. Calculate and plot the current decay during the time until the current decays to zero.

d. Calculate and plot the torque during the time periods investigated in parts (b) and (c).