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. 19, 1991
Filed:
Apr. 20, 1989
Masao Iwasa, Chiba, JP;
Yasutami Kito, Aichi, JP;
Otis Elevator Company, Farmington, CT (US);
Abstract
The present invention is achieved with a control unit for a PWM inverter for comparing (8) a voltage command signal (7) with the fundamental of the inverter's output voltage waveform and for comparing (11) the result with a carrier signal (10) and using that result to keep the output voltage waveform equal to the voltage command signal. The use of the output's fundamental for feedback eliminates the prior art need to use slight delays in the inverter's switching stage thereby removing the prior art torque ripple and consequent vibration problems particularly at low speed and furthermore enables smoother stopping and starting control using variable speed ranges of several hundred to one.