JPS6266162A - Time division multiplication type electronic watt-hour meter - Google Patents

Abstract

PURPOSE:To prevent a noise and a surge component from being mixed into a device, by constituting a multiplying circuit of a photocoupler having a bidirectional conducting property, and executing an insulation between an electronic circuit which has been provided on the post-stage of the multiplying circuit and a pulse modulating circuit which has been provided on the pre-stage of the multiplying circuit. CONSTITUTION:An analog voltage signal A is inputted to a pulse width modulating circuit 21 through an analog voltage signal input system 20, and its circuit 21 has a function for bringing the signal A to a pulse modulation and outputting as a time series a modulated pulse B having a pulse width being proportional to its voltage. A multiplying circuit 22 is provided on the post-stage of this circuit 21. This circuit is constituted of a photocoupler having a bidirectional conducting property. In this way, a noise component and a surge component which are mixed in the pulse B are eliminated by the circuit 22, therefore, it can be prevented that the noise component and the surge component are mixed into an electronic circuit which has been provided on the post-stage of the circuit 22.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an improvement in a time-division multiplication type electronic watt-hour meter.

(Prior Art) Conventionally, a time division multiplication type electronic watt-hour meter has been equipped with a pulse width modulation circuit 1 and a multiplication circuit 2, as shown in FIG.
The analog voltage signal A shown in FIG.
The modulated pulse B is modulated into a modulated pulse having a pulse width proportional to the voltage, and the modulated pulse B is generated in time series, and the modulated pulse B is multiplied by the analog current signal C shown in FIG. 3 in a multiplier circuit 2. , a current pulse signal having a pulse width corresponding to an analog voltage value and an amplitude value corresponding to an analog current value is generated in a time series, and the product VI of the amplitude value of the current pulse signal and the pulse width V is obtained. is proportional to the instantaneous power W, and the rectified signal obtained by rectifying the current pulse signal is proportional to the electric power. Therefore, the current pulse signal is rectified in the rectifier circuit 3 as an electronic circuit, and the rectified signal is The voltage/frequency conversion circuit 4 converts the frequency, and inputs it as a frequency signal corresponding to the amount of electric power to the frequency dividing circuit 6 while insulating it via the unidirectional conductive photocoupler 5,
The integrated power amount (Kwh) is converted into power amount and displayed on the display circuit 7. In Fig. 1, 8 indicates an analog current signal input system, 9 indicates an analog voltage signal input system, and the analog voltage signal A and analog current signal B are schematically enlarged views of the vicinity of the zero point of the sine wave alternating current. This is an indication.

Furthermore, Figure 4 shows the conventional configuration of a conventional time-division multiplication type electronic watt-hour meter that measures and displays the total amount of power of multi-phase AC such as three-phase AC, and shows an analog current signal corresponding to each phase. Input system 10.11, switch 14.15.16 to switch to analog voltage signal input system 12.13 corresponding to each phase,
I7 is provided, and the pulse width modulation circuit 1 is controlled by the control circuit 18.
The analog voltage signal input to the multiplier circuit 2 is alternately switched for each phase, and the analog current signal input to the multiplier circuit 2 is alternately switched for each phase to generate a current pulse signal in time series. There is a pulse width modulation circuit 1,
Each of the multiplier circuits 2 and the like is configured as a single unit in order to reduce costs and improve circuit accuracy.

(Problem to be Solved by the Invention) Conventionally, the multiplication circuit 2 uses an analog switch such as a transistor/transistor logic circuit TTL. Input current signal C and turn on/off its gate with modulation pulse B.
It is turned off and the current pulse signal is taken out from the drain side, but in order to turn the gate on and off, it is necessary to convert the modulation pulse B to the signal level of the transistor/transistor logic circuit TTL. There is a problem that the total number of circuit points increases and the cost increases. Further, the analog voltage signal A is extracted by the potential transformer PT and resistance division, but is led directly from the distribution line to the pulse width modulation circuit 1, and compared to the analog current signal C, it has noise components,
Surge components are likely to mix in, and the rectifier circuit 3, voltage/frequency conversion circuit 4, etc., which are electronic circuit components provided after the multiplier circuit 2, may malfunction or be destroyed due to these noise components and surge components. There is a problem with sexuality.

Furthermore, in the case of time-sharing multiplication type electronic watt-hour meters that measure and display the total amount of power of multiphase AC, analog switches have traditionally been used for the changeover switches, and these analog switches have fast switching speed and high accuracy. While this is good, it has the problems of high cost and poor insulation properties.

(Objective of the Invention) Therefore, the object of each invention of the present application is to provide a time-sharing multiplication type electronic watt-hour meter that can reduce costs and can also be expected to improve reliability. be.

(Means for Solving the Problems) A feature of the time-sharing multiplication type electronic watt-hour meter according to the first invention of the present application is that the multiplication circuit is constructed from a photocoupler having bidirectional conductivity. .

A feature of the time division multiplication type electronic watt-hour meter according to the second invention of the present application is that the changeover switch is constructed from a photocoupler having bidirectional conductivity.

(Function) According to the time-sharing multiplication type electronic watt-hour meter according to the first invention, the electronic circuit provided after the multiplication circuit and the pulse width modulation circuit provided before the multiplication circuit are integrated. 1@ between
It is possible to improve the green color, and it is possible to prevent noise components and surge components from entering the electronic circuit provided after the pulse width modulation circuit.

According to the time-sharing multiplication type electronic watt-hour meter according to the second aspect of the invention, it is possible to prevent noise components and surge components from entering the pulse width modulation circuit and multiplication circuit provided after the changeover switch.

(Example) Hereinafter, an example of the time-sharing multiplication type electronic watt-hour meter according to the present invention will be described based on the drawings.

FIG. 5 shows an embodiment of the time-sharing multiplication type electronic watt-hour meter according to the first invention of the present application. In FIG. 5, 19 is an analog current signal input system, and 20 is an analog voltage A signal input system, analog current signal system 19
and analog voltage signal input system 20 are directly connected to the power distribution line. The analog voltage signal A is input to the pulse width modulation circuit 21 via the analog voltage signal input system 20,
The pulse width modulation circuit 21 has a function of pulse modulating the analog voltage signal A and outputting modulated pulses B having a pulse width proportional to the voltage in a time series manner. A 1 multiplier circuit 22 is provided after the pulse width modulation circuit 21 . This multiplication circuit 22 is composed of a photocoupler having bidirectional conductivity. Here, a photocoupler having bidirectional conductivity is used because the analog current signal C and the analog voltage signal A are alternating current signals. A photo triac, a photo thyristor, a photo solid state relay, etc. are used for this photo coupler. This photocoupler is connected to the pulse width modulation circuit 2.
Switching is performed every time a modulation pulse is output from 1.

The multiplier circuit 22 multiplies the modulated pulse B and the analog current signal C to time-sequentially generate a current pulse signal having a pulse width corresponding to the analog voltage value and an amplitude value corresponding to the analog current value. , has a function of outputting the current pulse signal to the rectifier circuit 23 provided at the subsequent stage of the multiplier circuit 22. A voltage/frequency conversion circuit 24 is provided after the rectification circuit 23, and the rectified signal is frequency-converted by the voltage/frequency conversion circuit 24, and is input to the frequency division circuit 25 as a frequency signal corresponding to the amount of electric power. The frequency is divided by the frequency circuit 25 and input to the display circuit 26, and in this embodiment, insulation is achieved by the multiplication circuit 22, so that it is not provided in the conventional time division multiplication type electronic watt-hour meter. The conventional unidirectional conductive photocoupler is no longer necessary.

According to this embodiment, the noise components and surge components mixed in the modulated pulse B are removed by the multiplication circuit 22 made of a photocoupler, so that the noise components and surge components are removed from the electronic circuit provided after the multiplication circuit 22. Contamination can be prevented, and the reliability of the time-division multiplication type electronic watt-hour meter can be improved with a simple configuration.

FIG. 6 is a diagram illustrating an embodiment of a time-sharing multiplication type electronic watt-hour meter according to the second invention of the present application. An example of measurement is shown. This system measures the phase-to-phase voltage of any two phases of the three-phase alternating current alternately and displays the integrated amount of electric power, and the analog current signal input system 10.
11. Photocouplers are used as the changeover switches 14, 15, and 6.17 of the analog voltage signal input system 12.13, and a photocoupler is used as the multiplier circuit 22.

According to this embodiment, the noise components and surge components mixed in the analog voltage signal A can be prevented from entering the pulse width modulation circuit 21, and the pulse width modulation circuit 21 can Not only can destruction be prevented, but also noise components and surge components can be prevented from entering the multiplication circuit 22.

In the embodiment described above, the frequency is divided by the frequency dividing circuit 25 and the measurement and display is performed, but it is also possible to use a microcomputer to perform the measurement and display.

(Effects of the Invention) As explained above, according to the first invention of the present application, the multiplication circuit that multiplies the modulated pulse and the analog current signal is configured with a photocoupler having bidirectional conductivity. Therefore, it is possible to achieve insulation between the input side of the stage before the multiplication circuit and the output side of the stage after the multiplication circuit, thereby preventing noise and surge components from entering the electronic circuit on the output side. Therefore, the reliability of the time division multiplication type electronic watt-hour meter is improved.

Further, according to the second invention of the present application, since a photocoupler is used for the changeover switch, it is possible to prevent noise components and surge components from entering at least the pulse width modulation circuit provided on the input side. It has a preventive effect.

Furthermore, since the number of parts can be reduced, there is also the effect of reducing costs.

[Brief explanation of drawings]

FIG. 1 is a block circuit diagram showing a schematic configuration of a conventional time-division multiplication type electronic watt-hour meter, and FIG. A schematic diagram illustrating the relationship; FIG. 3 is a schematic diagram illustrating generation of a current pulse signal based on the modulated pulse signal and analog current signal input to the multiplication circuit shown in FIG. 1;
FIG. 4 is a block circuit diagram showing still another configuration of a conventional time-division multiplication type electronic watt-hour meter, and FIG. 5 is a block circuit diagram of a time-division multiplication type electronic watt-hour meter according to the first invention of the present application. FIG. 6 is a block circuit diagram for explaining the first embodiment. FIG. 6 is a block circuit diagram for explaining the embodiment of the time-sharing multiplication type electronic watt-hour meter according to the second invention of the present application. A... Analog voltage signal B... Modulation pulse C. Analog current signal D... Current pulse signals 14 to 17... Changeover switch 19... Current signal input system 20... Voltage signal input system 21. ... Pulse width modulation circuit 22 ... Multiplication circuit 23 ... Rectifier circuit

Claims (3)

[Claims] (1) a pulse width modulation circuit that pulse width modulates an analog voltage signal input through an analog voltage signal input system and outputs modulated pulses with a pulse width proportional to the voltage in a time series; and the pulse width The modulation pulse provided after the modulation circuit multiplies the modulation pulse output from the pulse width modulation circuit by the analog current signal input via the analog current signal input system, and generates the pulse width and analog current corresponding to the analog voltage value. a multiplication circuit that outputs a current pulse signal having an amplitude value corresponding to the current pulse value in time series; and an electronic circuit that is provided after the multiplication circuit and measures and displays the amount of electric power based on the current pulse signal. 1. A time-division multiplication type electronic watt-hour meter comprising: a time-division multiplication type electronic watt-hour meter, characterized in that the multiplication circuit comprises a photocoupler having bidirectional conductivity. (2) A pulse width modulation circuit that pulse width modulates the analog voltage signal input through the analog voltage signal input system corresponding to each phase and outputs modulated pulses with a pulse width proportional to the voltage in time series. is provided after the pulse width modulation circuit, and multiplies the modulated pulse output from the pulse width modulation circuit by an analog current signal inputted through an analog current signal input system corresponding to each phase, thereby generating an analog signal. a multiplier circuit that outputs a current pulse signal in time series having a pulse width corresponding to a voltage value and an amplitude value corresponding to an analog current value; and an analog voltage signal corresponding to each phase is input to the pulse modulation circuit. a changeover switch that changes over the analog voltage input system so that the analog voltage input system is inputted to the multiplication circuit; a changeover switch that changes over the analog current input system so that the analog current signal corresponding to each phase is input to the multiplication circuit; an electronic circuit for measuring and displaying the total power amount of each phase based on the current pulse signal; and a time-sharing multiplication electronic watt-hour meter, wherein the switching circuit is a photocoupler having bidirectional conductivity. A time-sharing multiplication type electronic watt-hour meter characterized by comprising: (3) The time-sharing multiplication type electronic watt-hour meter according to claim 2, wherein the multiplication circuit is composed of a photocoupler having bidirectional conductivity.