In a closed-loop control architecture, which component is primarily responsible for comparing the requested speed with the actual speed and generating an error signal?

• A. Drive
• B. Comparator
• C. Sensor
• D. Amplifier

Answer: (B)

In a closed-loop control system, the essential step is producing an error signal by subtracting the actual speed from the requested speed. This difference tells the system how far off it is from the target and guides adjustments to reach the setpoint. The component that performs this subtraction is the comparator (often called a summing junction). It takes the speed command and the feedback from the speed sensor, computes the error, and outputs it to the controller or drive to adjust the motor output.

The sensor provides the actual speed reading, which is the input for feedback. The drive is the actuator that powers the motor based on the control signal. The amplifier boosts signals as needed to drive the motor. These roles are important, but they do not generate the error signal themselves—the comparator does that crucial subtraction to produce the error used to correct the system.