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:
Feb. 27, 2001
Filed:
Mar. 30, 2000
Seiichi Oshima, Tokyo, JP;
Mitsubishi Denki Kabushiki Kaisha, Tokyo, JP;
Abstract
A control for controlling the DC output voltage of a boosting active filter constant. When a load changes from a rated condition to a light load or a no-load condition and the output voltage rises, a conventional active filter control device externally forces the active filter to stop and restart to suppress the voltage rise. In this process, an excessive inrush current occurs and the reactor produces abnormal sound. In addition, the conventional technique cannot be adapted to the PAM control. Accordingly, in the disclosed control of an active filter, first and second resistors and a control power supply are provided between an output terminal of a main circuit and ground, and the voltage at a node is input to one input end of a first differential amplifier and one input end of a hysteresis comparator. The output of the comparator is connected to an output end of a second differential amplifier through a signal line. The voltage at the node is kept equal to a reference voltage even if the output voltage set value is changed by changing the control voltage of the power supply, thus providing an overvoltage protection function which can follow variation of the output voltage set value. Such an active filter can be applied to a load such as a PAM-controlled inverter, AC servomotor, etc.