JPH01292265A - Input voltage detection circuit - Google Patents

Abstract

PURPOSE:To reduce the number of circuit elements, by detecting the drop of input voltage by a circuit consisting of a level detection circuit, a V-F converter, a mixing circuit and a separation circuit. CONSTITUTION:Input voltage is supplied to a level detection circuit 1 and a V-F converter 2 to be compared with reference voltage and binarized corresponding to the magnitude thereof to be outputted. In a mixing circuit 3, the output of the level detection circuit 1 and that of the V-F converter 2 are superposed one over another to by synthesized. The synthesized output is converted if necessary by a signal converting element 4 to be supplied to a separation circuit 5. Two synthesized signals are separated by the separation circuit 5 and the output of the level detection circuit 1 is supplied, for example, to a power failure processing circuit 8 and the signal from the V-F converter 2 is supplied to an F-V converter 6. The F-V converter 6 again converts the signal converted to frequency to voltage to supply said voltage to an input voltage monitor processor 7.

Description

[Detailed Description of the Invention] [Summary] This invention relates to an input voltage detection circuit that compares an input voltage with a certain reference value to detect an abnormality therein, and that enables constant monitoring of the input voltage value. The purpose is to reduce the number of input voltages, detect a drop in input voltage relative to a certain reference voltage, and constantly monitor the input voltage value. a level detection circuit that converts the input voltage change into a frequency change, a V-F converter that converts the input voltage change into a frequency change, and the output of the level detection circuit
A mixing circuit that combines the outputs of the converters, and a mixing circuit that receives the output of the mixing circuit via a transmission line and connects it to the output of the level detection circuit and V-
A separation circuit that separates the output of the F converter, a monitoring device that receives the output of the level detection circuit from the separation circuit and monitors the input voltage level, and a monitoring device that receives the output of the V-F converter from the separation circuit and converts the signal into a voltage. and an F--converter for converting and supplying the input voltage to a processor that monitors the input voltage.

[Industrial application field]

The present invention relates to an input voltage detection circuit that compares an input voltage with a certain reference value to detect an abnormality thereof, and that can constantly monitor the input voltage value.

[Prior Art] Conventionally, as shown in FIG. 4, this type of circuit rectifies an input voltage, compares the resulting pulsating voltage with a certain reference value,
Since the processor 7 determines the input voltage level based on the output signal of the level detection circuit 1 that obtains a binarized output, if you want to detect several types of levels, you need as many level detection circuits and this circuit. The same number of signal conversion elements 4 (for example, photocouplers, etc.) are used to insulate the human input signal and the output signal between the processors.

[Problems to be Solved by the Invention] As mentioned above, in conventional circuits, the number of level detection circuits and signal conversion elements increases in accordance with the number of levels that need to be detected, and as a result, the number of components increases. Problems that needed to be solved were a decrease in reliability due to an increase in the amount of electricity, and an increase in manufacturing costs.

SUMMARY OF THE INVENTION An object of the present invention is to reduce the number of circuit elements used, to detect a drop in input voltage with respect to a certain reference voltage, and to constantly monitor the input voltage value.

[Means to solve the problem]

In the present invention, as illustrated in FIG. 1, level detection circuits l, v -1? An input voltage detection circuit is provided comprising a converter 2, a mixing circuit 3, a separation circuit 5, an F-V converter 6, and a monitoring device 8.

Input voltage is level detection circuit 1 and V-F converter 2
The level detection circuit 1 compares the input voltage with a certain reference voltage, and outputs the binarized signal depending on its level. In the V-F converter 2, a change in input voltage is converted into a change in frequency and output. In the mixing circuit 3,
The level detection port 1 and the output of the V-F converter 2 are superimposed and synthesized.

The combined output is converted (insulated) by, for example, a signal conversion element or the like as necessary, and is supplied to the separation circuit 5 via a transmission line. The separation circuit 5 separates the two combined signals,
The output of the level detection circuit 1 is supplied to a monitoring device, for example, the power failure processing circuit 8, and the signal from the -F converter 2 is supplied to the F-F converter 2.
It is supplied to the V converter 6. The F-V converter converts the signal converted into a frequency into a voltage again and supplies it to the processor 7.

[For production]

By using the above-described circuit, it is possible to determine whether the input voltage is higher or lower than a certain reference voltage, and, for example, to detect a power outage. Additionally, the voltage value of the input voltage can be notified to the input voltage monitoring processor in parallel. Furthermore, the detection point and the monitoring point can be connected with a minimum number of transmission lines.

〔Example〕

A block diagram of an input voltage detection circuit as an embodiment of the present invention is shown in FIG. This circuit is level detection circuit 1.
It includes a V-F converter 2, a mixing circuit 3, a signal conversion element 4, a separation circuit 5, an F-V converter 6, and a power outage processing circuit 8 as a monitoring device.

The level detection circuit 1 receives and rectifies the input AC voltage, compares the rectified pulsating voltage with a certain reference voltage, converts it into a binary value, and provides a pulse output. This aspect is shown in the first and second rows of FIG. 2 and the waveform diagram of FIG. 3. The detection level in the figure corresponds to the reference voltage.

The V-F converter 2 converts the input AC voltage into a signal whose frequency changes and outputs the signal.

The outputs of the level detection circuit 1 and the V-F converter 2 are combined by a mixing circuit 3 so that the number of transmission lines can be reduced. In the mixing circuit 3, the above two outputs are superimposed. The combined output is converted via the signal conversion element 4, and the transmission waveform is transmitted as is, but is electrically isolated.

For example, a photocoupler or the like is used as the signal conversion element 4.

The output of the signal conversion element 4 is supplied to the separation circuit 5 via a transmission line. The separation circuit 5 separates the composite signal into states before being mixed by the mixing circuit 3.

Among the aforementioned separated signals, the signal corresponding to the output of the level detection circuit 1 is supplied to the power outage processing circuit 8, which monitors the input voltage based on this pulse waveform. For example, if the voltage drops below the reference value, it is determined as a power outage. Notice. Among the separated signals, the signal corresponding to the output of V-F converter 2 is F
-V converter 6 , the F-V converter 6 performs inverse conversion of the V-F converter, and supplies the voltage signal to the input voltage monitoring processor 7 . Thereby, changes in the voltage value of the input voltage can be sequentially notified to the processor.

FIG. 2 shows a waveform diagram in the circuit of the embodiment.

The first stage shows a process in which the input AC voltage is rectified into a pulsating voltage in the level detection circuit 1, and is compared with a certain reference voltage (detection level). The second stage shows the compared output signals of the level detection circuit 1.

The third stage shows the output signal of the V-F converter 2, and the fourth stage shows the superimposed waveform of the second and third stage signals.

The output of the F-V converter 6 is shown at the bottom.

FIG. 3 is a diagram illustrating the output signal of the level detection circuit when the input voltage is lower than the reference voltage.

〔Effect of the invention〕

According to the present invention, a drop in input voltage with respect to a certain reference voltage can be detected, and the input voltage value can be constantly monitored. Moreover, the number of circuit elements used is small, and therefore a circuit with high reliability and low manufacturing cost can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an input voltage detection circuit as an embodiment of the present invention, FIGS. 2 and 3 are waveform diagrams in the circuit of FIG. 1, and FIG. 4 is a diagram of a conventional input voltage detection circuit. It is a block diagram. In the figure, ■...Level detection circuit, 2...V-F converter, 3...Mixing circuit, 4...Signal conversion element,
5... Separation circuit, 6... F-V converter, 7... Input voltage monitoring processor, 8... Power failure processing circuit. Output signal of F-V converter OV-11--1111-Waveform diagram of circuit of embodiment Output waveform diagram of level detection circuit'$ 3 times

Claims (1)

[Claims] A level detection circuit (1) that binarizes and outputs an input voltage according to its level with respect to a reference value; and a V-F converter (2) that converts a change in the input voltage into a change in frequency. , a mixing circuit (3) that combines the output of the level detection circuit (1) and the output of the V-F converter (2), and a mixing circuit (3) that receives the output of the mixing circuit (3) via a transmission line to detect the level. a separation circuit (5) that separates the output of the circuit (1) and the output of the V-F converter (2); and a separation circuit (5) that receives the binarized output of the level detection circuit (1) from the separation circuit (5). a monitoring device (8) that monitors an input voltage level; and a processor (7) that receives an output from the V-F converter (2) of the separation circuit (5), converts a frequency signal into a voltage, and monitors the input voltage. ); and an input voltage detection circuit.