Results of study of quantization and discretization error of digital tachometers with encoder

What is it about?

The analysis of measuring channels of angular velocity with an encoder given by the authors made it possible for the first time to obtain an equation for estimating the quantization and sampling error for an exponential mathematical model describing the transient process of operation of electrical machines. The components of the mathematical model of this dynamic error are the sampling step and the derivative, which characterizes the rate of change of the measured value over time. It was found that the errors of quantization and sampling significantly depend on the value of the resolution z of the encoder. Moreover, an increase in z leads to a decrease in the sampling error, but the relative quantization error increases. To reconcile these components of errors, the laws of change in the distinguishing ability z of the encoder are adaptive to the dynamic properties of the change in angular velocity over time.

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Why is it important?

Currently, to intensify the testing of electric machines, the vast majority of research is focused on the acceleration of tests carried out in the no-load experiment. The main one here is the transient characteristic (variable angular velocity over time, which is obtained in the dynamic mode of operation of the measuring object (electric machine) with practically zero moment of resistance on its shaft. To ensure the maximum number of measured values of angular velocity during the transition process (3-5)tau, most researchers focused their choice on digital measuring channels with encoders, the main components of which are the following: measurements object OB, coupling shaft MC, encoder E, shaper F, device for the period selection T, f0 frequency generator G, AND logic gate for the TX period quantization, binary counter CT2, programmable PI interface (parallel or serial), MPS microprocessor system.