CHAPTER 6
DISCUSSIONS AND CONCLUSION
6.1. Discussions
The study provides a direct comparison of PID and Fuzzy speed controllers
applied to the same DTC-based PMSM drive for EV applications. Both controllers
were tested using the same motor parameters, inverter, DTC structure, reference
conditions, and simulation environment, providing a consistent basis for comparison.
The results show that both controllers can regulate the PMSM speed and follow the
required reference under different operating conditions.
The simulation results also show differences in dynamic performance between
the two controllers. The PID controller provides a simple and effective speed-control
response with good reference tracking, while its performance depends strongly on the
selected controller gains. The Fuzzy speed controller uses speed error and changes of
speed error to determine the control action and provides more flexible behavior when
operating conditions change. The comparison of electromagnetic torque responses also
shows differences in torque variation and stability during changes in speed and load
conditions.
Under the selected EV operating conditions, both controllers demonstrate their
ability to maintain motor speed during flat-road, uphill, downhill, and load-change
conditions. Therefore, the results indicate that controller selection affects the speed
and torque behavior of the DTC-based PMSM drive. The comparison provides a
practical basis for identifying the advantages and limitations of PID and Fuzzy speed
controllers for EV propulsion applications.
6.2. Conclusion
In conclusion, this study compared PID and Fuzzy speed controllers for a
DTC-based PMSM drive used in EV applications under the same motor, inverter,
DTC, and simulation conditions. The results show that both controllers can track the
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reference speed under different operating conditions. The PID controller provides a
simple and effective speed response, while the Fuzzy speed controller provides more
flexible control based on speed error and change of speed error.Overall, the
comparison shows that both controllers are suitable for DTC-based PMSM EV
propulsion, but they provide different speed and electromagnetic torque responses.
The Fuzzy speed controller showed more stable torque behavior in the evaluated
conditions, while the PID controller provided reliable speed tracking with a simple
control structure. Therefore, the selection of the speed controller depends on the
required speed-tracking and torque-response performance of the EV drive.