Study on determination of an asynchronous motor’s reactive power by the current-to-voltage converter

Abstract

Abstract This article presents a method for determining the primary currents, non-sinusoidal and asymmetrical currents flowing through the stator windings of an asynchronous motor based on the signal in the form of the output voltage from the current converter loops placed in each phase between the poles of the asynchronous motor stator and in the arrangement of the stator windings. Differences and characteristics of output signals are researched based on independent, series and opposite (bifilar) connection schemes of asynchronous motor current converter loops of measuring coil. In order to determine the value of the currents generated in each phase of the asynchronous motor stator windings, the output signals of the current converter with independent loop and loops connected in series were mutually analyzed. Measuring non-sinusoidal and asymmetrical currents, according to the opposite (bifilar) connection scheme, the loops of measuring coils are placed in the inter-pole grooves of each phase of the stator in the order corresponding to the three-phase stator windings, the current converter measuring coils each consists of two loops, bifilarly connected to each other. The end of loops of the measuring coils has two exits. Diodes and phase meter-regulators are placed on the first outputs of the loops, and they are oppositely connected to the microprocessor unit for measuring and controlling the asymmetry. The second outputs of the loops are connected directly opposite to the microprocessor unit for measuring and controlling non-sinusoidal currents. This type of current converter is important for determining the non-sinusoidal and asymmetrical currents generated in asynchronous motors, it increases the functional capabilities and accuracy of the current converter, and based on the determined results, it simplifies theoretical calculations, and at the same time, the dynamic and it will be possible to determine the static characteristics through theoretical differential equations. As a result of the research, practical and theoretical results were compared.