An electrical drive controls the torque, speed, direction and braking of a motor-driven system. It combines a power source, power converter, motor, controller, sensors and mechanical load. AC and DC drives use different converter and machine arrangements, but both must satisfy the load’s speed-torque profile and duty cycle.
The sections below cover drive selection, speed control, braking and servo systems. Compare continuous and peak torque, acceleration, inertia, speed range, four-quadrant operation, stopping duty, thermal limits, supply harmonics, electromagnetic compatibility, feedback accuracy and fault response. Variable-speed operation can reduce energy on a varying load, but total savings depend on the load profile and the part-load efficiency of the converter, motor and driven equipment.
