Lutsenko V. Developing and researching switching converters of signals of thermocouples

Research object: processes of measurement of small values of electric signals thermocouples by a switching method which provides raise of sensitivity simultaneous growth of act of influencing factors. Research purpose: raises of sensitivity, fast operation and accuracy of measurement and the control of temperature in three-zoned grouting furnaces due to use of switching transformation of a thermo-emf. Research methods and apparatus: methods of cal-culation and analysis of electric and magnetic circuits, methods of measurement of electric magnitudes, methods of the theory of probability and mathematical statistics, methods of the theory of the metrology and computer modeling, methods of circuitry and programming of microprocessor devices. Theoretical and practical results: methods of creation of switching converters of thermo-emf and systems of measurement and the control of temperature over furnaces which set up on the developed methods measurement of a thermo-emf of thermocouples, are offered. Novelty: the method of switching transformation of a thermo-emf and method of measurement of a thermo-emf in a regime of a leakage of an external current through junction of thermocouple are proved and developed. They allow receiving a conversion coefficient of value of a thermo-emf in amplitude of an output pulse about 103, that determines raise of sensitivity of measurements in as much time. The methods allow excluding effect of allocation of Joule heat on formation of test affecting on the basis of heat Peltie; method of compensation of switching noise is developed. The method is based on compensation of magnetic streams created by switching interferences which result from work of field transistors in the core of the transformer. This method allows to raise noise immunity and to lower a limit of sensibility of measurements; mathematical expressions which connect parameters of output signal with parameters of the switching converter, formulas for calculation value of sensitivity of the switching converter for thefirst time are received, and the optimum regime of his work which is characterized by the maximum value to a conversion coefficient is determined; the specified mathematical models for definition multiplicative and additive lapses of a measuring channel of a thermo-emf are developed for the first time; it has allowed to determine extent of agency of lapses of the switching converter pa-rameters on resulting value of a lapse and to establish the physical nature of formation of the relation signal / noise during switching. Degree of introduction: the center of a heading of scien-tific results "Elent A" (Dnepropetrovsk), laboratory of nonlinear - optical frequency converters the Zaporozhye state engineering academy (Zaporozhye). Sphere of the use: systems of measurement and the control of temperature in three-zoned furnaces