Pressure control system of the pumping units with frequency-controlled induction motor

Abstract

The ever-increasing demands to the quality of production processes are associated with the pumping of nonviscous liquids, which indicate the need in improving operating conditions of liquid transfer systems with centrifugal pumps, including by means of mathematical modeling. The purpose of the paper is to develop a system for stabilizing the pressure in the calculated point by a scalar frequency-controlling of an induction motor speed, and to study its dynamic operation modes. The following methods are used in the research: theory of the variable frequency drive and electrical machines, methods of operational calculus, theory of centrifugal bladed machines. As a result, a scheme for controlling the pressure of the centrifugal pumping unit in the calculated point by controlling the rotational speed of the induction motor and determining calculated pressure indirectly using the respective models of the centrifugal pump was developed.

The measuriment of ferromagnets magnetic characteristics using Labview software

“…Magnetizing force varies with time not harmonically, but as a non-periodical function. At the same time, the dependence of magnetic induction on magnetic field density is described with the help of a dynamic, not static, hysteresis loop [6,7]. Dynamic hysteresis loop of magnetic materials influences much on the value and the form of the excitation current curve of alternating current multi-purpose transformers and electric machines, and defines their weight, dimensions and energy consumption.…”