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, 1996
Filed:
Nov. 04, 1993
Johannes P Bahlmann, Eindhoven, NL;
Henricus M van Hout, Eindhoven, NL;
U.S. Philips Corporation, New York, NY (US);
Abstract
A motor drive circuit for driving an electromotor having a permanent magnet rotor and a stator comprising one or more stator windings. When the supply voltage of the motor drive circuit fails, an emergency signal is generated by a signal generator. This emergency control signal activates an auxiliary power supply circuit for extracting electric energy from the motor and supplying the extracted energy to an auxiliary circuit. The auxiliary power supply circuit comprises a rectifier circuit formed by the fly back diodes bridging the switches of an electronic commutation circuit. The drive circuit comprises short-circuit switches bridging the stator windings. In response to the emergency control signal a short-circuit apparatus causes the stator windings to be temporarily intermittently short-circuited. As a result, a capacitor is charged. The energy stored in the capacitor is used for temporarily energizing the auxiliary circuit once the power supply to the drive circuit has failed. If the drive circuit is used with a hard disc drive, the energy supplied by the auxiliary power supply circuit can be used for moving the magnetic head to an idle position.