Development Of A High Precision Digital Electric Energy Meter

Requirements of electric energy meter are growing rapidly, because people are paying more attention to electric energy measurement and power quality, and the government has made some policy about electric energy. Precision and stability of traditional electric energy meter are far from optimal, parameter that it can measure is little, requirements can't be satisfied. However, digital electric energy meter can make up for these disadvantages, it has higher precision, almost all of the parameters can be measured. It has a very fast rate and low cost. The most suitable method is using electric energy special chip or digital signal processing. Therefore, manufacture of digital high-precision electric energy meter is a focus.Firstly, this paper presents a plan, which uses 16-bit ultra-low power MCU MSP430F149, three-phase electric energy special chip ATT7022B, and 32-bit fixed-point DSP TMS320F2812. Among these three chips, the function of MSP430F149 is reading electric energy parameters, controlling LCD, operating keys, saving data, and communicating with monitoring computer. The function of ATT7022B is measuring voltage, current, power, and so on. The function of TMS320F2812 is measuring harmonics.Secondly, this paper has checked FFT and its implement method on DSP, and analyzed MCU, DSP, periphery circuits of electric energy special chip, including signal conditioning circuit, SPI communication circuit, data storage circuit, LCD circuit, DSP periphery circuit, and power circuit, and so on. To achieve the function of networking, this paper compiles a monitoring computer interface which can read and save electric energy parameters instantly using LabVIEW. Automatic meter reading is achieved.Finally, it can be concluded that this electric energy meter has high precision, low consumption, networking, multifunction, and can replace many traditional watt-hour meter, in order to achieve automatic data acquisition and control. Precision of voltage, current and power meet the requirements, and it can measure harmonic ratio. This electric energy meter achieves the requirement of industrial and agricultural production.