Speed Control of a Three-Phase IM with Closed-Loop Control Scheme

The chapter delves into the speed control of three-phase induction motors (IMs) using closed-loop control schemes. It begins by explaining the necessity of speed regulation in various applications and discusses both stator and rotor side control methods. The v/f control method is highlighted, which maintains a constant air-gap flux by varying voltage and frequency simultaneously. The chapter also explores sensorless strategies, such as direct torque control (DTC), and intelligent techniques using PI controllers for real-time estimation and improved performance. Additionally, it covers advanced control systems like automated PLC systems and hybrid PWM techniques, which reduce ripple and improve harmonic distortion. Mathematical modeling and simulation of VSI-fed IM with closed-loop control are discussed, along with practical implementations using PCs and add-on cards. The chapter further explores the use of Z-source inverters and model-based embedded system designs in MATLAB for enhanced efficiency. It also compares different PWM approaches and their impact on motor performance. The chapter concludes with a comparative study of open-loop and closed-loop control methods, emphasizing the benefits of closed-loop control in reducing harmonics and improving overall motor performance.