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. 24, 2004
Filed:
May. 02, 2002
Delta Electronics, Inc., Taoyuan, TW;
Abstract
The invention relates to an apparatus and a method for detecting a current direction in a PWM converter or an inverter having one or more upper and lower arms, each of which consists of a switching device with an anti-parallel diode. The voltage across the switching device presents a different value and a polarity that depend on the direction of the current flowing through the switching device, wherein the current direction is acquired by sampling this voltage in the period of the trigger signal being on. In a case of small current, this sampled voltage value is relatively large to the flowing current magnitude and is easy to be distinguished. Furthermore, this invention presents a method for obtaining the phase angle between the load current and the output voltage, and judging whether the output current is zero or includes DC component. As a result, this method presents high precision.