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:
Jul. 28, 2015
Filed:
Jun. 01, 2009
Shinichi Nomura, Chiba, JP;
Ulrich Schroder, Saint Marcel, FR;
Shinichi Nomura, Chiba, JP;
Ulrich Schroder, Saint Marcel, FR;
Edwards Japan Limited, Chiba, JP;
Societe de Mecanique Magnetique, Saint Marcel, FR;
Abstract
Provided are a compact and low-cost motor driver circuit capable of achieving an appropriate brake time and restraining heat generated by a regenerative resistance within a specific temperature range without employing a regenerative resistance having a greater capacity, a heat sink, or a FAN generating a larger volume of air, and a vacuum pump having the motor driver circuit. Regenerative current is controlled so that a speed characteristic gradually approaches inclination 'a' from inclination 'b' depending on the motor speed in the initial stage of regeneration. In addition, a limit is set not to pass further current when the regenerative current reaches a maximum brake current value I. As stated above, when the motor is braked, control is performed so that the initial brake current value at the maximum rated speed is set low and the brake current is increased as the rotational speed decelerates.