JPH0448111Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention uses a power supply equipped with a rectifier circuit to determine the state of an input AC signal to the power supply, such as waveform disturbance and the presence or absence of continuity of the input AC signal. This invention relates to a power supply input monitoring circuit that monitors power supply input monitoring circuits.

(Prior Art) FIG. 4 is a configuration and connection diagram showing an example of a conventional input monitoring circuit used in a power supply. In the figure, 11 and 12 are input terminals of a power supply to which an AC signal ei is applied, 13 is a rectifier circuit that rectifies the AC signal to a DC signal, 14 is a smoothing capacitor that smoothes the rectified output, 15 is an input monitoring circuit, 16, 17 is the output terminal of the power supply, from which the smoothed DC signal is output.
get eo.

The input monitoring circuit 15 receives an AC signal at one input terminal.
It consists of a comparator CP that inputs ei through diodes D ₁ and D ₂ and inputs a specified voltage ER to the other input terminal. In this case, the comparator CP outputs an alarm signal ALM.

(Problem to be solved by the invention) However, in an input monitoring circuit with such a configuration, when the rated value of the input AC signal ei is changed or the circuit constants are changed, the optimum value is set each time. The voltage ER must be adjusted,
There was a problem that the number of adjustment steps increased.

The present invention was developed in view of these problems, and its purpose is to monitor the input of a power supply that has a simple configuration and can respond to changes in the rated value of the input AC signal ei and changes in the circuit constants. This is an attempt to realize a circuit.

(Means for Solving the Problems) The present invention, which solves the above-mentioned problems, is an input monitoring circuit for a power supply equipped with a rectifying and smoothing circuit that rectifies and smoothes an input AC signal to obtain a DC signal, and includes the above-mentioned steps. A rectifier circuit that double-wave rectifies an input AC signal to a power supply to obtain a signal containing ripples that is not smoothed, a signal containing ripples obtained from this rectifier circuit, and an output DC signal of the rectifier and smoothing circuit. and an alarm output circuit that detects that the repeated signal outputted from the comparison means remains at a low level or a high level for a predetermined period of time or more and outputs an alarm signal. This is a power supply input monitoring circuit characterized by the following.

(Example) FIG. 1 is a configuration and connection diagram showing an example of a circuit according to the present invention. In the figure, 11 and 12 are input terminals of a power supply to which an input AC signal ei is applied. 13 is a rectifier circuit, here a bridge rectifier circuit. 14 is a smoothing capacitor, and 16 and 17 are output terminals that output a smoothed DC voltage eo. 15 is an input monitoring circuit which is a feature of the present invention. In this input monitoring circuit, D1 and D2 are diodes constituting a rectifier circuit that rectifies the AC signal ei input to the power supply to obtain a signal ei1 containing a ripple component (an unsmoothed signal). CP is a comparator, to which a signal ei1 containing unsmoothed ripple obtained by rectification by diodes D1 and D2 is applied to one input terminal, and to the other input terminal the DC output obtained at both ends of the capacitor 14 is applied. A voltage ed obtained by dividing the voltage eo (that is, a signal related to the DC output voltage eo) is applied. 18 detects whether the repetitive signal output from the comparator CP has been at a low level or high level for a predetermined period of time t or more, and detects whether the waveform of the input AC signal is disturbed or there is no trace of continuity. This is an alarm output circuit that outputs an alarm signal ALM indicating that the

The operation of the circuit configured as described above will now be explained with reference to the operational waveform diagram of FIG.

In comparator CP, one input terminal (+) has
A signal ei ₁ obtained by full-wave rectification of the input AC signal ei shown in FIG. 2A is applied. At the other input terminal (-),
The pulsating signal obtained by smoothing the full-wave rectified signal is connected to the resistors R ₁ and R ₂
A divided voltage signal ed shown in A, which is divided by , is applied.

Therefore, if the input AC signal ei is continuously supplied from the comparator CR and there is no abnormality in the waveform, the high level and low level will be output at a period t corresponding to the period of the AC signal ei, as shown in (b). A rectangular wave signal PO with repeating levels is output.

On the other hand, if the input AC signal ei becomes discontinuous as shown by the broken line in C, or if the waveform is significantly disturbed, the time period during which it is at a low or high level is shown as shown in D. , is longer than the period t.

The alarm output circuit 18 is configured to include, for example, a microcomputer, and uses a counting function to measure the time during which the signal PO output from the comparator CR is at a low level or a high level. When it becomes larger than t, an alarm signal ALM indicating that the input AC signal ei is in an abnormal state is output as shown in E.

FIG. 3 is a configuration and connection diagram showing another example of the circuit of the present invention. In this embodiment, the alarm output circuit 1
8, a transistor Tr ₁ which is turned on and off by a signal from a comparator CR, the above-mentioned charging circuit 19 consisting of a resistor R and a capacitor C whose charging and discharging are controlled by turning on and off this transistor Tr ₁ , and a capacitor C. It consists of a comparator _CP1 that compares the voltage EC across the voltage EC and the reference voltage EV.

If the signal from the comparator CP is a square wave signal that repeats high level and low level with period t, then
The voltage EC across the capacitor C is the voltage across the transistor Tr ₁
Charging and discharging is repeated with a period t, and the reference voltage
It will not be higher than EV. If the level of the signal from the comparator CR continues at low level or high level for a time longer than the period t, the charging time or discharging time becomes longer, the voltage EC across the capacitor C becomes higher than or lower than the reference voltage EC, and the voltage level of the comparator CP increases. Outputs the alarm signal ALM from the output terminal of ₁ .

In the embodiment shown in FIG. 3, the input AC signal ei is rectified by a rectifier circuit 20 composed of a diode bridge at one input terminal of the comparator CR.
The output is applied.

(Effects of the invention) As explained above, the present invention, in the input monitoring circuit, rectifies the input AC signal in both waves so that the signal applied to one input terminal of the comparator CP contains a ripple component that is not smoothed. The signal applied to the other input terminal is a signal related to the DC output voltage obtained by rectifying and smoothing the input AC signal.

For this reason, even if the rated value of the input AC signal ei or the circuit constants of the input circuit are changed, the comparator CP
Since the two signals applied to both change in the same way, the relative relationship between the two signals remains unchanged and no special adjustment is required. Therefore, it is possible to provide an input monitoring circuit that can respond to changes in the rating of input AC signals, changes in input circuit constants, etc. with a simple configuration.

In addition, the signal obtained from the comparator is a signal that repeats at a constant period in a steady state where the waveform of the input AC signal is normal and continuity is maintained, and the waveform of the input AC signal becomes abnormal. In this case, it appears as a change in the time that the signal remains at low level or high level repeatedly. Therefore, the waveform of the input AC signal can be monitored by measuring the time during which the repetitive signal from the comparator is at low level or high level.

[Brief explanation of the drawing]

Fig. 1 is a configuration and connection diagram showing an example of a circuit according to the present invention, Fig. 2 is its operating waveform diagram, Fig. 3 is a configuration and connection diagram of another embodiment of the present invention, and Fig. 4 is a diagram of a conventional circuit. It is a configuration connection diagram. 13, 20... Rectifier circuit, 14... Smoothing capacitor, 15... Input monitoring circuit, _D1 , _D2 ... Diode, CR... Comparator, 18... Alarm output circuit.

Claims (1)

[Claims for Utility Model Registration] An input monitoring circuit for a power supply equipped with a rectification and smoothing circuit that rectifies and smoothes an input AC signal to obtain a DC signal, the circuit rectifying and smoothing the input AC signal to the power supply in both waves. a rectifying circuit that obtains a signal containing a ripple component without using the rectifying circuit; a comparison means that compares a signal including a ripple component obtained from the rectifying circuit with a signal related to the DC output voltage of the rectifying and smoothing circuit; 1. An input monitoring circuit for a power source, comprising: an alarm output circuit that detects that a repetitive signal output from the means remains at a low level or a high level for a predetermined period of time or more and outputs an alarm signal.