Servo drives, also known as "servo controllers" or "servo amplifiers," are controllers used to control servo motors. They function similarly to variable frequency drives with standard AC motors, forming part of the servo system and are primarily used in high-precision positioning systems. Control of servo motors is typically achieved through position, speed, and torque, enabling high-precision transmission system positioning, which is a product of transmission technology.

Servo drives are an essential component of modern motion control, widely used in automated equipment such as industrial robots and CNC machining centers. Particularly, servo drives for controlling AC permanent magnet synchronous motors have become a hot research topic both domestically and internationally. In current AC servo drive designs, the three-loop control algorithm based on vector control is commonly used for current, speed, and position. The rational design of the speed loop is crucial for the overall servo control system, especially for the performance of speed control.