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. 14, 1989
Filed:
May. 10, 1988
John T Boys, Auckland, NZ;
University of Auckland, Auckland, NZ;
Abstract
A method and apparatus is shown to control both the motor terminal current to vary in exact proportion as the motor shaft torque varies for any given excitation frequency. This obviates the need for ancillary motor speed control and prevents voltage boosting at low speeds from resulting in excessive motor losses for no load conditions. A motor is powered from an inverter, the inverter providing an output voltage with independent control of amplitude and frequency. A frequency signal is fed directly to the inverter from a frequency input, the frequency input also being connected to a multiplier. The multiplier provides the amplitude signal for the inverter based on the product of the input frequency and motor current.