This Motor Control Sensor Feedback Circuit Diagram article is written by Jim Lepkowski from Microchip Technology Inc. Sensors in motor control are used to sense the current, position, speed and direction of the rotating motor. In most motor control systems, several sensors are used to provide feedback information on the motor. These sensors are used in the control loop and to improve the reliability by detecting fault conditions that may damage the motor.
The three most popular current sensors in motor control applications are: Shunt resistors, Hall effect sensors, and Current transformers. Shunt resistors are popular current sensors because they provide an accurate measurement at a low cost. Hall effect current sensors are widely used because they provide a non-intrusive measurement and are available in a small IC package that combines the sensor and signal-conditioning circuit. Current-sensing transformers are also a popular sensor technology, especially in high-current or AC line-monitoring applications.