## 4 Discussion  
As shown in Figure 5, the low-speed mode for EV is 40 km/h. It is evident from the waveform that the total time taken by the FM-PI controller is 1.4 s, with an overshoot of 12.5%. The IM begins operation from the rest position. Hence, the torque reaches its maximum limit of 300 Nm. Due to this huge torque value, a large current is required to change the state of the motor from rest to motion. As the control action proceeds towards the referenced speed, both torques, and the three phases, the current value drops exponentially. A zoom view of the phase-to-phase voltage, V\({}_{\text{ab}}\), is presented in Figure 6.  
Figure 5: IM application in the EV model for speed mode (0–40), comparing its effects on torque, current, and voltage. Figure 7 shows that the 60 km/h medium-speed mode is followed by 40 km/h in the lower speed mode. The control operation from the resting position to a lower speed takes 1.4 s, while it takes 1.1 s from low speed to medium speed. Hence, the total time taken by the FM-PI controller is 2.5 s, while the overshoot for the second speed transition is observed as 5%. The simulated model follows two reference speed commands to reach the step speed through a closed-loop PI control operation. Initially, the current and torque reach the maximum value. While the motor achieves a set speed value, at this point the current value drops with the decay in rotor torque, dropping to the minimum value. It reaches a stable speed at 3.1 s, with the torque and current both approaching minimum values. As presented in Figure 8, the high-speed mode at 80 km/h is followed by a medium-speed mode at 60 km/h. The protocol to reach a high speed in less time is to adopt the medium-speed mode from the rest position, followed by a high-speed transition. For a speed step of 60 km/h, initially, the FM-PI controller takes 1.7 s to reach medium speed, while from the second transition at 2 s, it takes 1.1 s from medium speed to high speed. Therefore, the total time taken by the FM-PI controller is 2.8 s, while the overshoot for the second transition is 4%. The general speed mode operation consists of four speed transitions, as presented in Figure 9. The model was subjected to a start from the rest position toward the low, medium, high, and brake transitions, respectively. The first step was at 40 km/h, then at 2.0 s for 40 km/h to 60 km/h. The next step was applied at 4.0 s for 60 km/h to 80 km/h, then, at 6.0 s, a brake was applied to deaccelerate the IM toward the rest position. At 2.0 s, the reference speed command instantly reached a value of from 40 to 60 km/h. The torque with  
Figure 6: Zoom-in voltage (V\({}_{\text{ab}}\)). Figure 7: IM application in the EV model for each speed mode (0–40, 40–60 km/h) to compare its effects on torque, current, and voltage. the current reached the maximum value to attain the required speed as early as possible, through vector control. The same behavior was observed at 4.0 s for the reference speed step from 60 to 80 km/h. When the machine finally achieved a speed of 80 km/h at 5.1 s, with torque and current both approaching minimum values over time, at 6.0 s, the torque took a negative maximum of 300 N.m., and the speed dropped toward the resting state. Finally, it reached the rest position at 7.7 s. The overshoot of the first, second, and third transitions remained the same, while the undershoot in the fourth transition is 22%. The additional driving scenario built for a load torque of 100 Nm, applied for low (40 km/h), medium (60 km/h), and high-speed modes (80 km/h), is presented in Figure 10. The waveform suggests that the PI-based model response time remained the same for all  
Figure 8: IM application in the EV model for the speed modes (0–60 and 60–80 km/h), to compare its effects on torque, current, and voltage. Figure 9: IM application in the EV model for all speed modes (0–40, 40–60, 60–80, and 80–0 km/h), to compare its effects on torque, current, and voltage. speed transitions.