A DIGITAL METER OF MUTUAL INDUCTANCE

Abstract

The problem of measuring the mutual inductance of magnetically coupled coils is considered, and the principle of its measurement by the phase method is described. A functional diagram of implementing the phase method is presented, and a mathematical model of the transformation is obtained. Based on the application of the phase method, the MIM-24 digital meter is developed and manufactured. The descriptions of the meter nodes are presented, the functions performed by them are presented, and the choice of microcircuits used in them is justified. The process of measuring and processing measurement results is controlled by a programmable microcontroller. A microcircuit of a controlled sinusoidal signal generator, which is programmatically controlled by a microcontroller, is selected as the power source of the measuring circuit. This eliminates the effect of changing the frequency of the power supply on the measurement results. The algorithm of the microcontroller program operation has been compiled. A method of experimental investigation of the metrological characteristics of the MIM-24 meter has been developed. The technique allows to evaluate the achievable accuracy of measuring the device. Measurements of mutual inductance within ohms are carried out on various samples of coils with a ferromagnetic core, and it is found that the limit of the main relative measurement error with a confidence probability does not exceed 0.75%. The device also measures the mutual inductance of coils without a ferromagnetic core when the distance between the coils changes. It is found that the relative measurement error increases with the removal of the coils, which is due to a decrease in their mutual inductance.