JP2564933Y2 - Input voltage abnormality detection circuit - Google Patents

Description

[Detailed description of the invention]

[0001]

INVENTION The present invention relates to relates to the input voltage abnormality detection circuit for detecting an abnormality of the AC input voltage, particularly, an AC wave
The present invention relates to an input voltage abnormality detection circuit that operates reliably even for a special AC input signal whose shape is missing for one cycle .

[0002]

2. Description of the Related Art Some electronic devices using a commercial power supply as a power supply are provided with an input voltage abnormality circuit for detecting a power failure.

FIG . 3 is a block diagram showing a conventional input voltage abnormality detection circuit. In a power supply unit using this input voltage abnormality detection circuit, a voltage supplied from an AC input power supply 11 is supplied to each unit of the electronic device via a power supply circuit 12. Then, the input voltage abnormality detection circuit
It is configured as follows. One end of the AC input power supply 11 is connected via the resistor 13 to one end of an input section 41 of an insulating element for detecting a positive voltage of the AC input voltage and an input section 51 of an insulating element for detecting a negative voltage of the AC input voltage. The other ends of the input sections 41 and 51 are connected to the other end of the AC input power supply 11 and grounded. Each input unit 41,
Reference numeral 51 includes, for example, a light emitting diode or a laser diode. The output section 42 of the insulating element for detecting the positive voltage of the AC input voltage and the output section 52 of the insulating element for detecting the negative voltage of the AC input voltage are composed of phototransistors. Power supply circuit 1
2, the output positive voltage (+ V ₀ ) is applied, and the emitter is connected to the ground SG of the power supply circuit 12 via the resistor 16 and to the delay circuit 21. The delay circuit 21 outputs an abnormal input voltage signal k.

In this input voltage abnormality detection circuit, a negative-to-positive zero-crossing detection signal h of the waveform of the AC voltage g supplied from the AC input power supply 11 is detected by the insulating elements 41 and 42, and the positive-to-negative zero-crossing is detected. Detection signal i
Detected at 1,52. Then, the delay circuit 21 outputs a constant pulse signal having a width of the delay time t ₁ by using the logical sum signal j of the detection signals of the both insulating elements as a trigger, and this output becomes the input voltage abnormality signal k. AC input power supply 11
Is an ordinary commercial sine wave, the input voltage abnormality signal k is always "H" in a normal state.

[0005]

[0006]

In recent years, uninterruptible power supplies such as rectangular waves and intermittent rectangular waves have become widespread as a measure against power failure.

FIG . 4 shows signal waveforms at various parts of the input voltage abnormality detection circuit when the AC voltage g is a rectangular wave. Also in this case, similarly to the stationary commercial sine wave, the zero-cross detection signal h from negative to positive is detected by the insulating elements 41 and 42, and the zero-cross detection signal i from positive to negative is detected by the insulating elements 51 and 52. However, because of the rectangular wave input, the rising and falling of the zero cross detection signals h and i are simultaneous. Therefore, the logical sum signal j input to the delay circuit 21 is always "H" and the trigger signal is lost, and the input voltage abnormality detection signal k is always "L", resulting in a malfunction.

As described above, in the conventional input voltage abnormality detection circuit, since the logical sum of the zero-cross detection signals h and i of the positive and negative voltages of the AC input waveform is obtained in the preceding stage of the delay circuit 21, it has been widely used in recent years. In the case of the uninterruptible power supply input waveform, for example, a rectangular wave, a malfunction occurs. Also,
Incorrect operation when AC waveform is missing in longer than half cycle
There was a problem of making.

Therefore, the purpose of the present invention is to make the AC waveform
An object of the present invention is to provide an input voltage abnormality detection circuit that can detect an abnormality of an input voltage without malfunction in a case where a period is lost .

[0010]

Means for Solving the Problems According to the invention of claim 1 ,
It is, traverse the zero-crossing point a positive voltage of (i) the AC input voltage
A positive voltage detector for detecting at that timing, the negative voltage detection means for <br/> detected at the timing crosses the zero-cross point a negative voltage of (b) the AC input voltage, a detection signal of (c) a positive voltage detector (D) first pulse output means for outputting a pulse signal having a time width of one cycle of the AC input voltage as a trigger;
AC input voltage triggered by the detection signal of the negative voltage detection means
Taking a second pulse output means for outputting a time width of one cycle of the pulse signal, a logical sum of the (e) the output signal of the output signal and the second pulse output means of the first pulse output unit, both The input voltage abnormality detection circuit is provided with an operation means for outputting an abnormality detection signal when neither the output signal nor the output signal is output.
You.

In this input voltage abnormality detecting circuit, the positive voltage of the AC input voltage is set at the zero cross point by the positive voltage detecting means.
Is detected at the timing crosses, a detection signal as a trigger, one cycle of the AC input voltage from the first pulse output means
Pulse signal having a time width of the output. Similarly, the negative voltage of the AC input voltage makes the zero cross point by the negative voltage detecting means.
Is detected at the timing crosses, a detection signal as a trigger, one cycle of the AC input voltage from the second pulse output unit
Pulse signal having a time width of the output. Then, the calculating means takes the logical sum of the output signal of the output signal and the second pulse output means of the first pulse output unit, making it outputs an abnormality detection signal when no output both the output signal
You. This allows any type of exchange with a fixed period
Abnormal input voltage is reliably detected regardless of its positive or negative waveform
Will be done.

[0012]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 relate to an embodiment of the present invention, and FIG. 1 is a block diagram showing a configuration of an input voltage abnormality detection circuit.

In the power supply section using the input voltage abnormality detection circuit of the present embodiment, the voltage supplied from the AC input power supply 11 is supplied to each section of the electronic equipment via the power supply circuit 12. The input voltage abnormality detection circuit is configured as follows. One end of the AC input power supply 11 is connected via the resistor 13 to one end of an input section 41 of an insulating element for detecting a positive voltage of the AC input voltage and an input section 51 of an insulating element for detecting a negative voltage of the AC input voltage. The other ends of the input sections 41 and 51 are connected to the other end of the AC input power supply 11 and grounded. Each input unit 41,
Reference numeral 51 includes, for example, a light emitting diode or a laser diode. The output section 42 of the insulating element for detecting the positive voltage of the AC input voltage and the output section 52 of the insulating element for detecting the negative voltage of the AC input voltage are constituted by phototransistors. The power supply circuit 12 is connected to the collector of the output section 42.
Output positive voltage (+ Vo) is applied and the emitter is a resistor 1
6 and to the ground SG of the power supply circuit 12 and to the delay circuit 18. Similarly, the output voltage of the power supply circuit 12 (+ V
o) is applied, the emitter is connected to the ground SG of the power supply circuit 12 via the resistor 17, and the delay circuit 1
9 is connected. The delay circuits 18 and 19 are constituted by, for example, monostable multivibrators. And
The OR circuit of the OR circuit calculates the logical sum of the output signal of the delay circuit 18 and the output signal of the delay circuit 19, and the output signal of the logical circuit 20 becomes the input voltage abnormality signal f.

In this input voltage abnormality detection circuit, the insulation elements 41 and 42 detect a zero-cross detection signal b of the waveform of the AC voltage a supplied from the AC input power supply 11 from negative to positive. triggered by the rise delay circuit 18 outputs a constant pulse signal d having a width of the delay time t _1. Similarly, the AC input power supply 11
The insulation elements 51 and 52 detect the zero-cross detection signal c of the waveform of the alternating-current voltage a supplied from the positive and negative sides, and the rising of the zero-cross detection signal c triggers the delay circuit 19 to delay the delay time t ₁ . A constant pulse signal e having a width is output. The logic circuit 20 calculates the logical sum of the pulse signal d from the delay circuit 18 and the pulse signal e from the delay circuit 19, and sets the output signal of the logic circuit 20 as the input voltage abnormality signal f. Note that the delay circuits 18, 1
The delay time t _{1 of} 9 is a half cycle (period) to one cycle of the waveform of the AC voltage a.

FIG. 2 shows signal waveforms at various parts of the input voltage abnormality detection circuit for various normal AC input voltages.
(A) shows the case of a steady commercial sine wave, (B) shows the case of a rectangular wave that is an uninterruptible power supply input waveform, and (C) shows the case of an intermittent rectangular wave that is also the uninterruptible power supply input waveform. ing. In the drawing, T indicates the cycle of the AC voltage g.

In any of the waveforms, when the AC input voltage is normal, a delay time t ₁ generated by using a zero-cross detection signal b from negative to positive of the waveform of the AC voltage a as a trigger.
Constant pulse signal e having a predetermined pulse signal d, the width of the delay time t ₁ generated a zero-cross detection signal c from the positive waveform of the AC voltage a to negative as a trigger having a width
Are not "L" at all, and these signals d and e
The input voltage abnormality signal f, which is the logical sum of the above, is always "H", indicating that it is normal.

[0019]

[0020]

[0021]

As described above, according to this embodiment, positive and negative zero-cross detection signals can be obtained for any AC input voltage such as a commercial sine wave, a rectangular wave of an uninterruptible power supply, and an intermittent rectangular wave. A pulse signal having a time width of one cycle of the AC input voltage is generated by using the signal as a trigger, and an abnormal input voltage signal is obtained by a logical sum of the two pulse signals. Abnormality can be detected.

[0023]

As described above, according to the present invention, the positive voltage and the negative voltage of the AC input voltage are respectively detected at the timing of crossing the zero cross point, and each detection signal is used as a trigger to trigger one cycle of the AC input voltage. Since the pulse signal of the time width of is generated and the abnormality is detected by taking the logical sum of both pulse signals, one cycle of the AC waveform is missing.
In such a case, there is an effect that an abnormality in the input voltage can be detected without malfunction.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an input voltage abnormality detection circuit according to an embodiment of the present invention.

FIG. 2 is a waveform chart showing signal waveforms at various parts of the input voltage abnormality detection circuit of FIG. 1 for various normal AC input voltages.

FIG. 3 is a block diagram showing a configuration of a conventional input voltage abnormality detection circuit.
FIG.

FIG. 4 shows a conventional input voltage abnormality detection circuit for a rectangular wave .
FIG. 3 is a waveform chart showing signal waveforms of respective units.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 AC input power supply 18 Delay circuit 19 Delay circuit 20 Logic circuit 41 Input part of insulating element 42 Output part of insulating element 51 Input part of insulating element 52 Output part of insulating element

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nao Hamamura Nippon Electric Engineering Co., Ltd., 3-20-4 Nishishinbashi, Minato-ku, Tokyo (56) References JP-A-49-8283 (JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A positive voltage of an AC input voltage is set to a zero cross point.
Positive voltage detection means that detects at the crossing timing, and timing that crosses the negative voltage of the AC input voltage across the zero cross point
A negative voltage detection means for detecting at grayed, AC input detection signal of the positive voltage detector as a trigger
A first pulse output unit that outputs a pulse signal having a time width of one cycle of a voltage, and an AC input triggered by a detection signal of the negative voltage detection unit as a trigger
Taking a second pulse output means for outputting a pulse signal of a time width of one cycle of the voltage, the logical sum of the output signal of the output signal and the second pulse output means of the first pulse output unit, both outputs An input voltage abnormality detection circuit, comprising: an arithmetic unit that outputs an abnormality detection signal when neither signal is output.