A standard electric drive is a closed-loop system typically composed of the following functional blocks:
The "brain" of the system that processes input commands and feedback to adjust the power modulator's operation. Fundamentals of electric drives
Regulates the power flow from the source to the motor to control speed and torque. Examples include rectifiers (AC-to-DC), inverters (DC-to-AC), and choppers (DC-to-DC). A standard electric drive is a closed-loop system
A simple method that maintains a constant voltage-to-frequency ratio; it is used in applications where precise control isn't critical. Fundamentals of electric drives