Method for improving precision of built-in real-time clock of electric energy meter MCU

Abstract

The invention discloses a method for improving the precision of a built-in real-time clock of an electric energy meter MCU. Based on the practical crystal oscillator frequency, fine compensation can be achieved. An electric energy meter comprises the MCU, a crystal oscillator and a power management unit. The method for improving the precision of the built-in real-time clock of the electric energy meter MCU includes the following steps of compensation amount calculation and clock calibration. Compensation amount calculation is performed according to the following processes that firstly, frequency deviations of the practical crystal oscillator under different temperatures are measured; secondly, a temperature-frequency deviation curve sketch is drawn, and the turn temperature T0 is found out; thirdly, the measured frequency deviations of the two sides of T0 undergo curve fitting, and a corresponding buckling constant is obtained; fourthly, a temperature-frequency deviation function table is formed according to a function of the third process, the frequency deviation value of the current temperature can be obtained through the temperature-frequency deviation function table according to the practical environmental temperature, and the frequency deviation value serves as the compensation amount for calibrating the clock under the practical environmental temperature. According to the method for improving the precision of the built-in real-time clock of the electric energy meter MCU, an accurate compensation value can be obtained according to errors of the practical crystal oscillator, and therefore the precision of the clock is improved.

Description

technical field [0001] The invention relates to a method for improving the precision of a real-time clock (RTC) built into an MCU of an electric energy meter. Background technique [0002] As a metering product for electric energy metering and electricity bill settlement, smart energy meters are required to have stable and accurate metering performance, so as to ensure that the interests of both electricity consumers and power suppliers are not damaged. At present, smart energy meters generally have time-sharing and multi-rate energy meters, and the requirements for time accuracy are getting higher and higher, and the problem of daily timing errors is also more prominent. In the rectification notice issued by the supplier, both Article 2 "Components Link" and Article 11 "Design and Manufacturing Process Link" focused on the problem of daily timekeeping error out-of-tolerance, requiring key rectification. According to the technical specifications of the smart energy meter of...

AI Technical Summary

Problems solved by technology

[0003] Chinese patent CN102176112A proposes a method for accurate timekeeping of a MCU built-in RTC real-time clock; although Deng Qianzhong's master's degree thesis "Research and Design of Self-Calibrating Real-Time Clock RTC" is a correction method proposed for hard clock design, the principle is the same as that of the Chinese patent The method proposed by CN102176112A is the same, and the deviation of crystal oscillator frequency with temperature is regarded as a parabola whose symmetry axis is parallel to the Y axis, such as Image 6 As shown, this is also the crystal frequency error model commonly used at present, but there is a certain discrepancy with the actual crystal frequency error, so the calibration accuracy will also be affected to a certain extent

Since there is a certain difference between the actual crystal oscillator curve and the typical crystal temperature-accuracy curve (the actual crystal oscillator curve is as follows figure 1 As shown), this will cause the final compensation amount to be unable to calibrate the frequency accurately, resulting in timing errors

Images