Electricity: battery or capacitor charging or discharging – Battery or cell discharging – With charging
Reexamination Certificate
1999-12-03
2001-01-09
Wong, Peter S. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell discharging
With charging
C324S430000
Reexamination Certificate
active
06172483
ABSTRACT:
BACKGROUND OF THE INVENTION
Impedance is a complex quantity. As such, it has two components: either magnitude and phase, or real and imaginary parts (i.e., resistance and reactance). These alternative forms of a complex quantity are equivalent.
Both components of impedance of an electrochemical cell or battery are meaningful. One can gain insight into many properties such as cranking power, state-of-charge, percent capacity, temperature, and physical condition by analyzing measurements of complex impedance obtained at selected “spot” frequencies. Heretofore however, complex impedance could only be determined with bridges or expensive laboratory instruments that were poorly suited to measuring batteries in the field (e.g., E. Willihnganz and Peter Rohner, “Battery Impedance”,
Electrical Engineering,
78, No. 9, pp. 922-925, September, 1959; see also David Robinson, “Electrochemical Impedance Spectroscopy in Battery Development and Testing”,
BATTERIES INTERNATIONAL,
31, pp. 59-63, April 1997).
R. S. Robinson, in PCT International Publication WO93/22666, teaches a method for measuring complex impedance of batteries in service. However, the apparatus he discloses is an FFT-based commercial signal analyzer (HP 3562A) and the disclosed method uses existing battery currents as excitation—currents that may not contain the frequency or frequencies desired.
Devices for measuring battery impedance described in the patent literature have been generally limited to apparatus that actually determines only one quantity. For example, patent references can be found for field apparatus that purports to measure battery “impedance” (e.g., U.S. Pat. No. 4,697,134 to Burkum et al, U.S. Pat. No. 5,773,978 to Becker) and battery “resistance” (e.g., U.S. Pat. No. 3,753,094 to Furuishi, U.S. Pat. No. 3,676,770 to Sharaf et al, U.S. Pat. No. 5,047,722 to Wurst et al). However, none of these patents disclose apparatus that measures two quantities. The present patent addresses this deficiency by disclosing a practical method, and its apparatus implementation, for accurately measuring real and imaginary parts of cell/battery impedance under actual field conditions—conditions that often include a high degree of electrical noise.
SUMMARY OF THE INVENTION
A periodic time-varying current excites a cell/battery and provides a timing reference. This current excitation need not be sinusoidal but need only be periodic with its smallest period equal to 1/f
1
, where f
1
is the desired measurement frequency. Linear circuitry senses two signals, one proportional to the time-varying excitation current, the other proportional to the responding time-varying component of battery voltage. The two signals are processed with identical frequency-limiting. filters to attenuate higher-order harmonics and noise. Using the timing reference for synchronization, a microprocessor or microcontroller commands analog to digital converters to sample the frequency-limited current and voltage signals at evenly spaced times over a period of the excitation and accepts the digitized samples as inputs. It then averages these samples over multiple periods and calculates averaged Fourier coefficients of in-phase and quadrature components of frequency-limited current and voltage at frequency f
1
. Finally, the microprocessor/microcontroller combines the four averaged Fourier coefficients numerically to evaluate real and imaginary parts of the cell/battery's complex impedance at frequency f
1
. The disclosed method and apparatus are quite inexpensively implemented and give very accurate results under typical field conditions—even under conditions of extreme electrical noise.
REFERENCES:
patent: 2514745 (1950-07-01), Dalzell
patent: 3356936 (1967-12-01), Smith
patent: 3593099 (1971-07-01), Scholl
patent: 3607673 (1971-09-01), Seyl
patent: 3676770 (1972-07-01), Sharaf et al.
patent: 3729989 (1973-05-01), Little
patent: 3753094 (1973-08-01), Furuishi et al.
patent: 3808522 (1974-04-01), Sharaf
patent: 3811089 (1974-05-01), Strezelewicz
patent: 3873911 (1975-03-01), Champlin
patent: 3886443 (1975-05-01), Miyakawa et al.
patent: 3889248 (1975-06-01), Ritter
patent: 3906329 (1975-09-01), Bader
patent: 3909708 (1975-09-01), Champlin
patent: 3936744 (1976-02-01), Perlmutter
patent: 3946299 (1976-03-01), Christianson et al.
patent: 3947757 (1976-03-01), Grube et al.
patent: 3969667 (1976-07-01), McWilliams
patent: 3979664 (1976-09-01), Harris
patent: 3984762 (1976-10-01), Dowgiallo, Jr.
patent: 3984768 (1976-10-01), Staples
patent: 4008619 (1977-02-01), Alcaide et al.
patent: 4053824 (1977-10-01), Dupuis et al.
patent: 4070624 (1978-01-01), Taylor
patent: 4086531 (1978-04-01), Bernier
patent: 4112351 (1978-09-01), Back et al.
patent: 4114083 (1978-09-01), Benham et al.
patent: 4126874 (1978-11-01), Suzuki et al.
patent: 4178546 (1979-12-01), Hulls et al.
patent: 4193025 (1980-03-01), Frailing et al.
patent: 4207611 (1980-06-01), Gordon
patent: 4315204 (1982-02-01), Sievers et al.
patent: 4316185 (1982-02-01), Watrous et al.
patent: 4322685 (1982-03-01), Frailing et al.
patent: 4363407 (1982-12-01), Barkler et al.
patent: 4369407 (1983-01-01), Korbell
patent: 4390828 (1983-06-01), Converse et al.
patent: 4392101 (1983-07-01), Saar et al.
patent: 4396880 (1983-08-01), Windebank
patent: 4408157 (1983-10-01), Beaubien
patent: 4412169 (1983-10-01), Dell'Orto
patent: 4423378 (1983-12-01), Marino et al.
patent: 4423379 (1983-12-01), Jacobs et al.
patent: 4424491 (1984-01-01), Bobbett et al.
patent: 4459548 (1984-07-01), Lentz et al.
patent: 4514694 (1985-04-01), Finger
patent: 4520353 (1985-05-01), McAuliffe
patent: 4667279 (1987-05-01), Maier
patent: 4678998 (1987-07-01), Muramatsu
patent: 4679000 (1987-07-01), Clark
patent: 4697134 (1987-09-01), Burkum et al.
patent: 4707795 (1987-11-01), Alber et al.
patent: 4709202 (1987-11-01), Koenck et al.
patent: 4710861 (1987-12-01), Kanner
patent: 4719428 (1988-01-01), Liebermann
patent: 4743855 (1988-05-01), Randin et al.
patent: 4816768 (1989-03-01), Champlin
patent: 4820966 (1989-04-01), Fridman
patent: 4825170 (1989-04-01), Champlin
patent: 4849700 (1989-07-01), Morioka et al.
patent: 4881038 (1989-11-01), Champlin
patent: 4912416 (1990-03-01), Champlin
patent: 4929931 (1990-05-01), McCuen
patent: 4931738 (1990-06-01), MacIntyre et al.
patent: 4947124 (1990-08-01), Hauser
patent: 4956597 (1990-09-01), Heavey et al.
patent: 4968941 (1990-11-01), Rogers
patent: 5004979 (1991-04-01), Marino et al.
patent: 5032825 (1991-07-01), Xuznicki
patent: 5047722 (1991-09-01), Wurst et al.
patent: 5087881 (1992-02-01), Peacock
patent: 5126675 (1992-06-01), Yang
patent: 5140269 (1992-08-01), Champlin
patent: 5144248 (1992-09-01), Alexandres et al.
patent: 5170124 (1992-12-01), Blair et al.
patent: 5204611 (1993-04-01), Nor et al.
patent: 5214370 (1993-05-01), Harm et al.
patent: 5214385 (1993-05-01), Gabriel et al.
patent: 5241275 (1993-08-01), Fang
patent: 5254952 (1993-10-01), Salley et al.
patent: 5281919 (1994-01-01), Palanisamy
patent: 5281920 (1994-01-01), Wurst
patent: 5295078 (1994-03-01), Stich et al.
patent: 5298797 (1994-03-01), Redl
patent: 5300874 (1994-04-01), Shimamoto et al.
patent: 5302902 (1994-04-01), Groehl
patent: 5331268 (1994-07-01), Patino et al.
patent: 5336993 (1994-08-01), Thomas et al.
patent: 5343380 (1994-08-01), Champlin
patent: 5352968 (1994-10-01), Reni et al.
patent: 5365160 (1994-11-01), Leppo et al.
patent: 5365453 (1994-11-01), Startup et al.
patent: 5381096 (1995-01-01), Hirzel
patent: 5426371 (1995-06-01), Salley et al.
patent: 5432426 (1995-07-01), Yoshida
patent: 5434495 (1995-07-01), Toko
patent: 5442274 (1995-08-01), Tamai
patent: 5449996 (1995-09-01), Matsumoto et al.
patent: 5449997 (1995-09-01), Gilmore et al.
patent: 5457377 (1995-10-01), Jonsson
patent: 5485090 (1996-01-01), Stephens
patent: 5488300 (1996-01-01), Jamieson
patent: 5519383 (1996-05-01), De La Rosa
patent: 5528148 (1996-06-01), Rogers
patent: 5550485 (1996-08-01), Falk
patent: 5561380 (1996-10-01), Sway-Tin et al.
patent: 5562501 (1996-10-01), Kinoshita et al.
patent: 5572136 (1996-11-01), Champlin
pate
Toatley Jr. Gregory J
Westman Champlin & Kelly P.A.
Wong Peter S.
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