| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a phase detector which can promptly detects a phase even if an amplitude, a phase and a frequency of an AC voltage are varied, and is improved in controllability. <P>SOLUTION: The phase detector for detecting the phase of the AC voltage in a power system comprises: a voltage detecting part (10) for detecting the AC voltage (v<SB>α</SB>=V<SB>p</SB>cosθs) in the power system; a PLL-phase detecting part (11); a voltage amplitude compensating part (12); a virtual β-axis voltage generating part (13); and a phase detection signal outputting line (19). The PLL-phase detecting part (11) obtains a detection phase (θ<SB>d</SB>) by using a means for converting the AC voltage (v<SB>α</SB>) and the virtual β-axis voltage (v<SB>β</SB>) in terms of a rotational coordinate by using the detected phase (θ<SB>d</SB>). <P>COPYRIGHT: (C)2009,JPO&INPIT |
