Povshenko O. Improvement of the rotational method of measuring the electrostatic field strength

The dissertation is devoted to the improvement of the rotational method of measuring the strength of the electrostatic field by reducing its measurement errors and the development of an improved information-measuring system (IMS) of the strength of the electrostatic field with increased accuracy and in a low measurement range from 0 to 1 kV/m. The main part of the dissertation work consists of four chapters, which are devoted to the study of ways to improve the rotational method of measuring the strength of the electrostatic field and the development of an improved IMS. The first chapter is dedicated to the overview of the problem and justification of the research direction of the dissertation work. The requirements for the hardware for measuring the voltage of the EF with increased accuracy in the low measurement range from 0 to 1 kV/m are substantiated. The selection of the rotational method of measuring the strength of the electrostatic field is justified. The second section of the dissertation is devoted to mathematical and computer modeling of the electrostatic field mill (EFM) sensor. The structure and physical principle of the EFM sensor are considered, and the requirements for its mathematical model are substantiated. An analysis of the common equation for the conversion of the electrostatic field strength into current, which describes the operation of the EFM sensor, and its imperfections were determined. An improved conversion equation is proposed and justified, which describes the operation of the EFM sensor, taking into account the limitations and imperfections that are present in the typical conversion equation. In order to compare the improved mathematical model of the EFM sensor with the typical one, a computer simulation of the EF distribution between the sensitive plates and shielding plate of the EFM sensor was carried out, and the numerical values of the charge induced on the sensor plate were determined and the value of the induced current was calculated. It is established that the waveform obtained using the improved transformation equation better corresponds to the real signal, compared to the typical one. The next part of the study was aimed at establishing the optimal configuration and structure of the EFM sensor: determining the value of the optimal distance between the sensitive plates and the shielded plate; determination of the value of the rational number of sectors. The third chapter of the dissertation is devoted to the development of an improved information and measuring system of the electrostatic field strength. A generalized structural scheme of the IMS of the EF strength is proposed and substantiated. In order to improve the current-to-voltage conversion scheme, the scheme of an ungrounded differential transimpedance amplifier with zero voltage drop is proposed and substantiated. Computer simulations of circuit noise parameters in the frequency range and the actual amplification factor for typical and proposed schemes of differential transimpedance amplifiers were carried out. The methodology for calculating the instrumental error of measuring the analog EF cascade is proposed and substantiated, and the influence of the quantization error on the overall result of measuring the strength of the EF is analyzed. The fourth chapter of the dissertation is devoted to the experimental study of the improved electrostatic field mill. An algorithm for digital processing of the measurement information obtained from the sensor of the improved EFM, as a result of calibrated measurement of the strength of the EF, is proposed and substantiated. The structure of the algorithm is presented and its main stages are substantiated: oversampling algorithm, digital filtering, processing of measurement results, amplitude analyzer of the signal sweep, storage and transmission of information. Methodical, algorithmic and software for calibrating the improved EFM has been developed. The calibration algorithm of the analog circuit of the electrostatic field mill and the EFM sensor is proposed and substantiated. A reference stand for sensor calibration has been designed. Methods of conducting an experimental study of measurement errors of the improved electrostatic field mill have been developed. The results of the conducted experiment are presented.