Electricity: motive power systems – Alternating current commutating motors – Universal or a.c.-d.c. motors
Patent
1983-11-23
1985-07-02
Witkowski, S. J.
Electricity: motive power systems
Alternating current commutating motors
Universal or a.c.-d.c. motors
364726, 324161, 318312, 318490, G06F 15332, H02K 2364
Patent
active
045271011
ABSTRACT:
An indirect speed sensor for an electric motor, such as an electric motor of the universal type, provides for a resistive element in series with the motor windings so that current pertubations that occur as a consequence of armature rotation are manifested as speed-dependent voltage signals across the resistive element. The voltage signals are amplified and filtered to remove frequency components above and below the expected signal spectrum and then provided to an analog-to-digital converter that converts the filtered analog signal to digital values that are stored in a memory. A stored-program controlled microprocessor analyzes the stored digital information by performing a fast Fourier transform to provide an equivalent amplitude spectrum. The maximum amplitude spectral component is then identified to determine the speed of the motor.
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Ro, Bentsu; Dissertation, University Microfilms International, Ann Arbor, Michigan, 1983, p. 35.
IEEE Communications, "The Discrete Fourier Transform Applied to Time Domain Signal Processing", vol. 20, No. 3, pp. 13-22, May 1982.
Ibid, "Time Domain Modeling and Digital Simulation of Variable-Freq. A.C. Motor Speed Control Using PLL Technique", vol. IA-19, No. 2, Mar./Apr. 1983, pp. 174-180.
Saar David A.
Zavis Wayne
Black & Decker Inc.
Murphy Edward D.
Ro Bentsu
Sherer Ronald
Weinstein Harold
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