You're looking for information on AC and DC motor control, specifically related to Gerald Moberg's work!
For AC motors, control techniques like Variable Frequency Drives (VFDs) are commonly used. VFDs adjust the frequency and voltage of the AC supply to control the motor's speed. Ac And Dc Motor Control Gerald Moberg Pdf
The PWM technique allows for efficient control of the motor's speed, as the motor's inertia helps to filter out the high-frequency switching. By adjusting the duty cycle, the motor's speed can be controlled. You're looking for information on AC and DC