An induction machine with the following parameters is controlled in the rotor flux linkage oriented vector control mode.

The impedances are evaluated at the rated frequency. The total inertia, JM + L, of the drive system is 1:0 kgm², and the total friction coefficient, B_{M + L,} of the drive system is 0:1 Nm/(rad/s). The internal connection of stator winding is assumed to be a Y connection. The torque component current has been zero and the flux component current has been set to keep the rotor flux linkage as 0.45 V/(rad/s). The drive system has been in the steady state. At t = 0 s, the torque command varies in step manner to 20 N-m. Plot the "a" phase current for 0-0.5 s. The current regulator can be assumed as ideal, which means that the transfer function of the current regulation loop is unity. At t = 0s, the direction of the rotor flux linkage coincides with that of the magnetic axis of "a" phase winding.