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:
Nov. 15, 1983
Filed:
Mar. 09, 1981
Shashi B Dewan, Toronto, CA;
Marathon Electric, Wausau, WI (US);
Abstract
A wound rotor motor apparatus includes an energy recovery circuit having a rectifier connecting the rotor circuit to a gated inverter having an input filter for return of rotor power to the three-phase power supply system. A voltage chopper circuit connects the rectifier to the recovery inverter and operates to establish and maintain a constant direct current voltage to the inverter regardless of motor speed. The voltage is greater than the line voltage and is returned at near unity power factor. The chopper circuit is dual gated thyristors. A first thyristor connects an inductor in series to the rectifier. The first thyristor is turned on at the chopper frequency and current flows through the inductor. A commutating thyrister in series with diode is connected in series with a first thyristor and a parallel and back-biasing diode. An inductor in series with a capacitor is connected across commutating thyristor and the inductor-capacitor junction is connected in series with a dropping resistor to the input of the inverter filter. Upon turn-on of the commutating thyristor, the LC circuit tries to ring and current flows through the back-bias diode and turns the first thyristor off. The inductor acts as a high voltage source to the inverter circuit and recharges the commutating capacitor. When the inverter is gated on, power is returned from constant high D.C. voltage supply to the A.C. Power supply.