JPS595968A - Apparatus for measuring electric power - Google Patents

Abstract

PURPOSE:To obtain an electric power measuring apparatus excellent in frequency characteristics, by constituting a multiplier and an adder by digial IC separately from a microprocessor. CONSTITUTION:Voltage input Ei and current input Ie are applied to preamplifiers PA1, PA2 to be converted to voltages V, I with predetermind levels and both voltages are applied to filters FL1, FL2 to be filtered. The outputs of the filters FL1, FL2 are converted to numerical value lines shown as digital data at every predetermined sampling cycle by analogue digital converters AD1, AD2. A multiplier MUL receivers the outputs of the analogue digital converters AD1, AD2 to multiply these voltage and current data and the numerical value lines being the multiplication result thereof are outputted. WA is an adder constituted by digital IC and the output of the multiplier MUL is inputted to the adder. The adder WA add the inputted numerical value lines to store the added result thereof. This added value is imparted to a microprocessor muP. The microprocessor applies necessary operations such as operation of coefficient or filtering on the basis of the inputted data to calculate electric power finally. The operation result is provided to a display circuit DIS to be displayed thereby.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a power measurement device using a microprocessor.

A conventional example of a power measuring device using a microprocessor is shown in FIG. In Figure 1, El is a voltage input, and E is a current input, and the power from both of them is converted into voltage and current signals at predetermined levels by preamplifiers PA□ and PA2, and then applied to analog-to-digital converters AD1 and AD2. , where n digital signals V□.

v2. v3...Vn and I□, Eng. , engineering,...
...Converted to In.

Analog to digital conversion like this! aAD, AD
The n digital signals obtained by 2 are led to the microprocessor νP. The microprocessor lIF calculates the following formula (
Perform the calculation shown in 1). Thereby, the electric power W is determined.

The power signal W in equation (1) is given to the display DIS, and its value is displayed.

A device in which a microprocessor (IF) performs the calculation for obtaining the power signal W shown in equation (1) as described above is conventionally known. However, in this device, the sampling period in the analog-to-digital converter AD AD is determined by the calculation speed of the microprocessor IJP, but since the calculation speed of the microprocessor IP is slow, a power measurement device with good frequency characteristics is required. It is difficult to obtain
In order to do this, the leaf must have a large memory capacity,
Requires something expensive. In addition, microprocessor I
All calculations in equation (1) can be performed using digital I, without using IP.
It is also possible to use C. In this case, calculations can be performed at high speed, and as a result, a device with good frequency characteristics can be obtained, but there is a drawback that the configuration becomes large-scale.

The present invention has been made in view of these points, and an embodiment thereof is shown in No. 2''li1.
is a voltage input, Ii is a current input, pAl and PL2 are preamplifiers, PL, PL2 are filters, and D and AD2 are analog-to-digital converters, respectively. Both people power E□
, 11 is a preamp, which is applied to the amplifier PjA□, PL2 and converted to a voltage of a predetermined level ■, I, and then applied to the filter F.
L1. It is added to PL2 and Shitonami is used. Filter F
L□.

The output of PL2 is an analog-to-digital converter AD1°A
D2, digital data v1. v2. v3...vn and 11. I2.
It is converted into a numerical string represented by I3...In. M
UL is a multiplier made up of a digital IC (logic IC).

The multiplier MUL is an analog-to-digital converter section.

AD, output V1. V2. V3・-Vn O-Length 1
．． Engineering 2. Step 3...Receive In, multiply these voltage and current data, and the multiplication result is vl・I,
V2・Engineering 2. Outputs a numerical string expressed as v3.I3...Vn.In. WA is a digital IC (logic I)
C), in which the adder is connected to the multiplier MU
L output v1・11. v2°work2°... is input. The adder WA inputs the input numerical string v1・D□, v2・I
2... and store the addition result. Therefore, the contents of adder WA after n samples are Σvk-Ik. This added value is given to the microprocessor pP. Microprocessor IJ
P calculates K based on the input data (Σvk・k), performs necessary calculations such as calculation of coefficient 1/n, filtering, etc., and finally calculates the power expressed by equation (1). Find W.

This calculation result is given to the display circuit DIS and displayed.

In the present invention having such a configuration, the voltage signals V□,
V2. V3... and current signals I,, I2. I
The multiplier MUL that multiplies 3... and the adder WA that adds the multiplication results are digital ICs (μ thick ICs).
IC consists of an integrated circuit) and a microprocessor lJ
P is configured so that only operations such as multiplying the addition result by a coefficient are performed, so basic operations such as multiplication and addition are determined by the operation speed of the digital IC7, and the microprocessor pp
Because it is not affected by the calculation speed (calculation speed of software), calculation processing can be performed at extremely high speed.

Therefore, according to the present invention, a power measuring device with good frequency characteristics can be obtained. Moreover, since the calculations are divided into the digital IC and the microprocessor IJP, and the operation is performed in the following 7 steps, the memory capacity of the microprocessor IIP does not increase, and the device does not require a large-scale installation over the next few years. Obtainable.

Note 1. The contents of the adder WA in the present invention's equipment are W.
If it's ac (ΣVk7 Ik), it's microprocessor! If we calculate WmWac/n within P, we can calculate 6 to find the power of - period.Here, 1. = T/18,
ts is a voltage signal V by providing an output circuit TC at the sun.
required from. Also, let the content of the adder WA after n samples be x□2nd-order result I2, and Y□-X, , Y
2”X2+ to 2Y1...Ym = Xm 10kmYn
If the calculation of -1 is performed by the microprocessor IJP, this becomes a first-order filter, so that the DC component of the electric power can be detected. Furthermore, in Fig. 2, Vr is a voltage adder and Ir is a current adder, but if both multipliers are Kvkt or I-, the voltage adder Vr and the current adder Ir have can. Although the WH watt/hour adder is used, it is also possible to measure watts/hour by receiving the output of the multiplier MUL with this adder and calculating the output with a microprocessor. By providing multiplication and addition functions separately from the microprocessor pP, various operations such as those mentioned above can be performed at high speed and
To increase the storage capacity of a microprocessor. It has the advantage of being able to do things without having to worry about it.

As described above, according to the present invention, since the multiplier and the adder are configured by digital ICs separate from the microprocessor, a power measuring device with excellent frequency characteristics can be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an example of a conventional power measuring device, and FIG. 2 is a block diagram of an embodiment of the device of the present invention. vessel. Agent Patent Attorney Shinsuke Ozawa (7)

Claims (1)

[Claims] A pair of analog/digital converters that convert voltage input and current input into digital signals, respectively, and a digital IC that multiplies the outputs of the pair of analog/digital converters.
a multiplier configured with a multiplier, an adder configured with a digital IC that adds the outputs of the multiplier, a microprocessor that receives the output of the kernel adder and performs a coefficient operation on the output of the adder, and an output of the microprocessor. A power measurement device equipped with a display that displays.