| 摘要 |
PURPOSE:To precisely measure electric energy by A/D-converting both D.C. current and voltage, performing moving-average-process, and multiplying them together, for integrating its output. CONSTITUTION:Analog current (i) and voltage signal (v) are inputted in the first and second sigma/delta modulation circuits 10 and 11, respectively, for A/D conversion. The outputs of 10 and 11 come into the second and fourth 16-tap moving average digital filters 14 and 15 by way of the first and third 16-tap moving average digital filters 12 and 13, respectively, and are connected to filters 12 and 13, respectively in parallel, thus constituting component means. In a multiplier 18, one eighth thinning means 141 and 151 remove one data out of eight data, in relation to the outputs of filters 14 and 15, for input. In a multiplier 19, on eight thinning means 161 and 171 do thinning with the outputs of filters 16 and 17, for input. Then the difference in the outputs of multipliers 18 and 19 is calculated by a subtracter 20, and then integrated by a counter 30 for electric energy. |
