Fast Speed Measurement Research Articles

Measurement of Speed and Calibration of Tachometers Using Rotating Magnetic Field

Fast speed measurement and control signals are required for feedback control applications. In the proposed technique, a rotating magnetic field (RMF) is used to measure the speed and the variation in speed with high accuracy. In addition to a 400 Hz, three-phase input voltage circuit and an output zero-crossing detector circuit, a contact-type synchro is used as a primary transducer. A balanced three-phase ac voltage is applied to the stator windings of synchro, which produces an RMF. The frequency of electromotive force induced in the rotor circuit of synchro depends upon the speed of rotor or rotating member. The RMF revolves at a speed of 24 000 r/min, which is purposely kept very high in comparison with the speed of the rotor or rotating member. Thus, the measurement becomes very fast and the change in speed is sensed within 2.5 ms. The time response of the proposed scheme is also compared with the time response of a dc tachogenerator. A digital storage oscilloscope and a microcontroller are used for measurement of the output. The 16-b digital output of the microcontroller is made available as a feedback signal for control applications. The high accuracy of measurement of the proposed technique is also successfully used for calibration of different contact- and noncontact-type tachometers.

Accurate and fast speed measurement using ramp-waveform sampling technique

A novel sampling technique for accurate and fast speed measurement is presented. Square pulses from an encoder are turned into ramps using analog electronics. They are then sampled, and linear regression is used on ramp-waveform sample points to extrapolate backward and determine the starting point of each pulse very accurately.

Microprocessor-Based Speed Control System for High-Accuracy Drives

A digital speed control system for a dc motor with a pulse tachogenerator for speed sensing is described. A microprocessor is used for fast speed measurement with a response time constant of the order of 8 ms and a resolution of 0.0125 percent of the top speed. This has become possible because of the principle of obtaining the latest speed value based on the previous speed value. This paper describes the principle of speed measurement and control, the flowchart, and the experimental results. A closed-loop speed holding accuracy of ±0.025 percent of the top speed is obtained.

A Fast and Accurate Speed Measurement System Using Microprocessor

A digital speed measurement system for a variable speed drive with a pulse tachogenerator is described. A microprocessor is used for fast speed measurement with a response time of the order of 8 ms, and a resolution of 0.0125%. This has become possible because of the principle of obtaining the latest speed value based on the previous speed value. The paper describes the principle of speed measurement, the flow-chart and the experimental results.