ACTIVE POWER MEASUREMENT ACCURACY INCREASING WITH SIGNIFICANT REACTIVE COMPONENT

Abstract

The broadband wattmeter of transient power with its own consumption error correction for measuring the active power against the background of large reactive components in the frequency range up to units MHz is described in the article. This instrument can measure the power loss (active power) in a variety of reactive elements, for example, the inductances used in pulsed energy converters. Such wattmeter can be used to optimize the development of wireless power transmission systems based on open resonance circuits. The structure of such systems, as was found during the study, has a spherical directional pattern and does not depend on the emitter and receiver location, described in the article. The article specifies the features of active power measurements at searching for the most efficient design of wireless power transmission systems on the basis of open resonant circuits, where the measurement is complicated by the fact that relatively small active power needs to be measured against the background of large reactive components, when the operating frequencies are shifted from the resonance, and phase shift between current and voltage accrue.At high frequencies measuring, the channels of the wattmeter become very sensitive to phase errors. It is necessary to minimize links that cause phase shifts. In this connection, it is important to construct correctly the wattmeter input units and to make such a transformation, which will provide operations with signal modules. The proposed scheme allows this to be achieved, and required gain is carried out without taking into account the signals phase shift.In the basic scheme of the wattmeter, the input device is executed from the main shunt and parallel to the auxiliary distributed shunt connected to it, which is connected to the main resistance of the voltage divider, in which the value of all resistances of the input device is determined by conditions of invariance to the squares of the voltage and load current, and the partially distributed auxiliary shunt is calculated with additional weighting factors to provide the conditions for invariance of the square of voltage and current and eliminate the error from its own revives.The value of the calculated power measurement error on the model for this wattmeter is 0,1%. The basic error of the wattmeter is the error of the low-ohm shunt. It is expedient to use coaxial or triaxial shunts to extend the frequency range. The designs of such shunts and examples of shunts with the best technical characteristics for today are given in the article.The advantages of such wattmeter are:- gives the exact value of the measured power on the load, regardless of the actual consumption of the input device;- the values of the input device elements can be optimized by the criterion of maximum broadband, since the error from its own consumption is taken into account;- one low-level shunt, which reduces the cost of the wattmeter; is used in the scheme- additive errors of the voltage conversion channel are minimized.