Abstract:

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Conventional controllers such as Proportional Integral Derivative (PID) are simple and easy to design and implement, but often compromise control quality under varying conditions. In contrast, intelligent controllers offer superior adaptability at the cost of design and tuning complexity. Hence, a comparison is necessary to achieve a suitable trade-off between simplicity and control quality in systems like Direct Current (DC) shunt motor speed control. A shunt DC motor has its field windings connected in parallel (shunt) with the armature windings. This configuration gives the motor numerous advantages, such as ease of control, low armature reaction, quick response and durability, among others. This paper presents a comparison of Model Predictive Control (MPC), PID tuned using Ziegler Nichols, and PID based Internal Model Control (IMC) approaches for speed control of the shunt DC motor. The controllers are tested through simulation under three distinct input scenarios, namely unit step, variable step, and random integer generator signals. Their performances are evaluated using standard control measures, including Rise Time, Settling Time, Overshoot, Integral of Absolute Error (IAE), and Control Effort. In each case, MPC records the lowest overshoot of 0%, 143% and 15.3% thereby demonstrating greater efficiency by minimizing control effort. However, PID_IMC achieves the lowest IAE, ranging from 0.3 to 12.3 (rad/s) and maintains the fastest settling time of 1.5 seconds, though all the controllers settle at the same time (15 seconds) for the random integer generator input. These results highlight the trade-off between accuracy and robustness: PID_IMC provides better accuracy in terms of tracking error, while MPC ensures robustness, lower overshoot, and reduced actuator demand, making it more suitable for systems operating under unpredictable conditions. The findings aim to assist control engineers in selecting where and when to choose between conventional PID and modern control techniques.

Keyward(s): Internal Model Control (IMC), Model Predictive Control (MPC), Overshoot; Proportional Integral Derivative (PID), Shunt DC motor

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