The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 18, 2015
Filed:
May. 29, 2013
Daihen Corporation, Osaka-shi, Osaka, JP;
DAIHEN Corporation, Osaka, JP;
Abstract
A phase difference detector detects the phase difference between two AC signals at a high speed and with high accuracy. A phase difference computation unit computes the phase difference φ(=φ−φ) between two detected voltages v(phase angle: φ) and v(phase angle: φ). The phase difference computation unit uses a sine wave vand a cosine wave vgenerated separately and having the same frequency as the fundamental frequency of the voltages vand v, to perform computation of v=v×v, v=v×v, v=v×v, v=v×v, and then extracts DC components I=(−A/2)·sin(φ), R=(A/2)·cos(φ), I=(−A/2)·sin(φ), R=(A/2)·cos(φ) at low-pass filters. The phase difference computation unit computes R=R×R+I×Iat a complex multiplying unit to obtain R=(A·A/4)·cos(φ), computes I=R×I−R×Ito obtain I=(A·A/4)·sin(φ), and computes φ=tan(I/R) at the arctangent calculation unit, thereby obtaining the phase difference φ.