Speed feedback is implemented in one of two ways the

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: voltage generated by the motor. Sensored Feedback There are a variety of sensors used for speed feedback. The most common are optical encoders and hall effect sensors. Optical encoders are made up of several components. A slotted wheel is mounted to the shaft at the non-driving end of the motor. An infrared LED provides a light source on one side of the wheel and a photo transistor detects light on the other side of the wheel (see Figure 9). Light passing through the slots in the wheel will turn the photo transistor on. As the shaft turns, the photo transistor turns on and off with the passing of the slots in the wheel. The frequency at which the transistor toggles is an indication of motor speed. In the case of positioning applications, an optical encoder will also provide feedback as to the position of the motor. FIGURE 9: OPTICAL ENCODER Slotted Wheel IR LED Front View Photo Transistor Side View DS00905B-page 5 AN905 Back Electro Magnetic Flux (BEMF) Hall effect sensors are also used to provide speed feedback. Like optical encoders, Hall effect sensors require a rotary element attached to the motor and a stationary component. The rotary element is a whe...
View Full Document

This note was uploaded on 01/29/2014 for the course AA AA taught by Professor Aa during the Winter '10 term at ENS Cachan.

Ask a homework question - tutors are online