Temperature Compensation And Auto-calibration Of High-Precision Electronic Balance

Electronic balance is a kind of intelligent weighing instrument and a kind of standard weighing instrument widely used in national defense, scientific research, factory and lab. It has the factions and traits of weighing fast, easy operation, automatic calibration, fault self-diagnosis and so on whose the mechanical balance are not able to have. Due to the high weighing precision and sensitivity, temperature drifts and time-varying drifts become the primary factors of weight of electronic analytical balance.This paper introduces the current development of electronic balance and analyzes the working principles and the main reasons which influence the precision of electronic analytical balance. It analyzes the reasons of time-varying drifts and temperature drifts and gives the new compensation for time-varying drifts and temperature drifts. Finally, this paper verifies the functions of electronic analytical balance which has been improved and analyzes the errors.Firstly, it calibrates electronic balance timely by the single-chip microcomputer controlling the motor drive which drives the standard weight. That makes the electronic balance use more easily. Automatic calibrating device is able to decrease the influence by time-varying drifts efficiently.Secondly, it proposes a new method of compensation for temperature through a large sum of high and low temperature experiment to the balance and analyzing the original principles of temperature drifts seriously. This method changes the voltage signal with temperature into digital quantity by V/F change and calculates the temperature compensation by the inner calculation of single-chip, and then makes compensation for software by sending compensation quantity to the main single-chip of electronic balance through a serial port. The results of experiment show that the new method of compensation has high practicability and precision. It can improve the calculating precision of electronic balance.Lastly, making comparisons of electronic balance before and after compensation and analyzing the errors of the improved system, it proposes some improving methods.