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:
Apr. 29, 1997
Filed:
May. 24, 1995
Herbert Stemmler, Kirchdorf, CH;
Thomas Eilinger, Winterthur, CH;
Inventio AG, Hergiswil, CH;
Abstract
A method and apparatus for the low noise operation of a electrical machine driven by a pulse inverter computes the amplitudes and frequencies of the harmonics of the inverter output voltages. Through targeted setting of the modulation parameters, the frequency spectrum or the noise spectrum can be fanned out and harmonics, which would excite stator resonances, can be eliminated. Due to the independence of the modulation parameters from the modulation index (a.sub.0) and the fundamental oscillation frequency (f.sub.1), the fanning-out and the elimination has no influence on the fundamental oscillation (u.sub.GS) or on the operating point of the machine. The inverter is controlled through sinusoidal pulse width modulation (PWM) and sinusoidal pulse frequency modulation (PFM) of a triangular carrier signal (U.sub.H). By this method, the main groups of the harmonics with two ordinate numbers (n, v) are fanned out into subgroups with three ordinate numbers (n, m, v). In addition to a more uniform distribution, there also is a reduction in the amplitudes of the harmonics (U.sub.nmv) through this fanning-out method. The generated noise is reduced in level and the sound pattern does not contain any conspicuous unpleasant individual frequencies.