The Hall Sensor Speed Detection System Design And Research

Recent years in engineering practice, with the rapid development of automatic control, automatic detection and information technology, the degree of industrial automation is enhanced continuously. In the automatic control system, the measurement of electric parameters and the measurement of engines, motors, machine tool spindles, and other rotating equipment on gear speed are made increasingly higher requirements.The engine speed is not a simple job parameter, but is the calculation basis of other parameters and correct datum in the electronic control system. Many hinge speed measurement is achieved by installing speed detection system. Speed signal is obtained by the measurement of the speed sensor and, if the sensor can not work steadily, electronic control system to control the engine will not work correctly. Therefore, the performance of the sensor is directly related to the performance of the electronic control system.Traditional speed sensors are generally used magnetic-electric sensors. Although magnetic-electric speed sensor has simple structure and low cost, but has the following disadvantages:If the speed is too slow and the output signal voltage is too low, the electric control system can not detect. If the speed is too fast and the output signal voltage is too high, it will appear pulses. The test results do not match the real speed. In addition, it has poor resistance to electromagnetic interference. However, Hall speed sensor has a series of advantages:It has s simple structure, small size, non-contact, high reliability, good thermal performance, long life, no spark, no self-excited oscillation, anti-pollution ability, sturdy, impact resistance, and many other advantages. In this thesis, the design of Hall sensor speed detection system is studied and analyzed. The author selects the appropriate Hall chip, designs amplifier and Schmitt shaping circuit and analyzes a variety of basic methods to measure the speed. Pulse counting method is adopted. As long as the shaft per revolution will result in one or multiple fixed pulse and the pulse will be sent into the microprocessor to count, you can get speed information. The sensor is installed in the shaft, when the blades pass by can produce pulse signals. And by use of constant current source compensation circuit, the bridge equivalent circuit method can improve the accuracy of pulse signal detection. Adopting one-chip computer systems composes hardware detection systems. Using single chip counter port settings counts on speed measurement, and through microcontroller software count one-chip timer/counter port settings on the pulse. On the basis of experimental data sets the pulse equivalent to achieve speed display. Optimization of the system software, use of watchdog circuit power-on reset improve system stability. After installing the hardware and software debugging, design of the system enables accurate measurement of the speed.It has low cost, good performance and simple structure, even in harsh environment it has a strong anti-interference ability, can be widely used in the speed measurement, processing, and display in electronic control system.