| 摘要 |
PROBLEM TO BE SOLVED: To calculate an effective value and a phase difference of an AC signal easily.SOLUTION: When an AC voltage and an AC signal are detected and then filter sections 51 and 52 extract a fundamental wave component, arithmetic processing in the filter sections 51 and 52 is performed by an expression (a1). Each of the filter sections 51 and 52 outputs a cosine wave and a sine wave of the fundamental wave component of an input, effective value computation sections 53 and 54 calculates AC voltage and an effective value of the AC voltage, and a phase difference computation section 55 calculates a phase difference &phgr;. |
