Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Electrical signal parameter measurement system
Reexamination Certificate
1999-03-08
2002-10-29
Bui, Bryan (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Electrical signal parameter measurement system
C702S064000, C324S142000, C361S079000
Reexamination Certificate
active
06473699
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a power arithmetic apparatus for calculating power from an AC current and voltage of a target measurement system.
FIG. 1
is a block diagram showing a conventional power arithmetic apparatus.
Referring to
FIG. 1
, terminals T
1
and T
2
input a voltage V
1
and a current A
1
in proportion to the voltage and current of a target measurement system. The voltages V
1
and A
1
are converted into digital values by A/D converters
1
and
2
, respectively. A CPU
3
calculates the digital values from the A/D converters
1
and
2
at a predetermined time interval.
The power arithmetic apparatus of this scheme serves as a wattmeter by calculating
P=V
1
·A
1
and performing integration for a predetermined time, or as a watthour meter by performing infinite time integration.
However, such power arithmetic apparatus has the following problems.
(1) Since the voltage V
1
and current A
1
are multiplied by software, multiplication instruction processing takes a time.
(2) Since calculation is performed by software, processing is complex and time-consuming, so another processing can hardly be performed by software.
(3) Conversion using A/D converters takes a time, so the sampling frequency can hardly be increased. To increase the accuracy, the number of bits is increased, although this results in an increase in cost.
BRIEF SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation, and has as its object to provide a power arithmetic apparatus capable of performing multiplication instruction processing in a short time, avoiding complex processing to allow software to perform another processing, and preventing an increase in cost even when the sampling frequency is increased.
To achieve the above object, according to a first aspect of the present invention, there is provided a power arithmetic apparatus comprising:
means for detecting a first variation amount in a voltage in proportion to a voltage of a measuring object and a second variation amount in a voltage in proportion to a current of the measuring object; and
means for calculating power of the measuring object based on the first variation amount detected and the second variation amount detected.
According to a second aspect of the present innovation, there is provided a apparatus according to first aspect,
wherein the means for detecting the first variation amount and second variation amount comprises:
a first A/D converter for converting the voltage in proportion to the voltage of the measuring object to a first digital signal indicating the voltage in proportion to the voltage of the measuring object;
a second converter for converting the voltage in proportion to the current of the measuring object to a second digital signal indicating the voltage in proportion to the current of the measuring object;
a first counter for outputting the first variation amount based on the first digital signal; and
a second counter for outputting the second variation amount based on the second digital signal.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.
REFERENCES:
patent: 4255707 (1981-03-01), Miller
patent: 5099195 (1992-03-01), Greer et al.
patent: 5170115 (1992-12-01), Kashiwabara et al.
patent: 5243276 (1993-09-01), Kashiwabara et al.
patent: 5369356 (1994-11-01), Kinney et al.
patent: 5448747 (1995-09-01), Garverick et al.
patent: 5924050 (1999-07-01), Maruyama
patent: 6097192 (2000-08-01), Obermeier et al.
patent: 0 772 052 (1997-05-01), None
patent: 9-292417 (1997-11-01), None
patent: WO 94/22024 (1994-09-01), None
Bui Bryan
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Kabushiki Kaisha Toshiba
LandOfFree
Power arithmetic apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Power arithmetic apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Power arithmetic apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2944006