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:
Oct. 31, 1978
Filed:
Oct. 26, 1976
Thomas P Gilmore, Wauwatosa, WI (US);
Frederick A Stich, Milwaukee, WI (US);
Allis-Chalmers Corporation, Milwaukee, WI (US);
Abstract
An adjustable speed AC electric motor drive has a static inverter energized from a unidirectional power source through a semiconductor series chopper and eliminates a filter between chopper and inverter and controls the fundamental inverter output frequency as a function of an analog speed reference signal and also pulse width modulates the series chopper at a constant frequency as a function of the speed reference signal and synchronizes the series chopper to the fundamental inverter freqency to provide variable voltage and variable frequency power to the motor. The drive has a shunt chopper at the output of the series chopper and switches it to the opposite conductive state from the series chopper so that it coacts with the feedback diodes to form substantially continuous, low impedance, bidirectional free-wheeling paths for motor current and provides constant harmonic content current to the motor with reduced ripple.