The section that handles speed commands and logic in a DC drive is the

• A. Control section
• B. Power section
• C. Feedback section
• D. Input stage

Answer: (A)

The part that processes speed commands and runs the control logic is the brain of the drive—the control section. It takes the speed reference from the user or system, compares it with the actual motor speed (from the feedback section), and computes the error. Using that error, it runs a control algorithm (often a PID loop) to generate a suitable drive signal that tells the power section how to adjust the motor current or voltage to reduce the difference between commanded and actual speed. In short, the control section translates a speed command into the appropriate control signal for the power electronics to execute.

The power section handles the heavy lifting of converting the control signal into actual power delivered to the motor. The feedback section provides the real speed measurement that the controller uses to know how well it’s tracking the command. The input stage is where user commands are initially entered and scaled, but the actual speed command processing and logic reside in the control section.