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:
Jun. 04, 1991
Filed:
Dec. 04, 1989
Wilhelm Reinhardt, Schrozberg-Gutbach, DE;
Karl-Heinz Schultz, Ohringen-Cappel, DE;
Abstract
Method and apparatus for driving an alternating-current motor. A sinusoidal supply AC voltage is rectified into a pulsating, unsmoothed DC voltage, with sinusoidal half waves and from this DC voltage an alternating-current motor voltage is produced by means of controllable polarity reversal. The pulse width of this alternating-voltage of the motor can be modulated. The polarity reversal takes place in accordance with the supply frequency in such a way that the AC voltage of the motor is essentially composed of the sinusoidal half waves of the pulsating DC voltage. For this purpose, the motor speed can be altered by changing the AC voltage of the motor with a constant timing frequency, lying outside the range of audibility, into pulse-width modulatable voltage pulses.