JP2003047169A - Power failure detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power failure detection device, which achieves power failure detection in an uninterruptive power supply device without accompanying a loss. SOLUTION: The power failure detection device, in the uninterruptive power supply device which makes a power supply from a DC power supply 1 secured, is constituted of a capacitor 4a connected to the output of the DC power supply 1, a differential circuit 5 to output a differential value of the voltage of the capacitor 4a, and a control circuit 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an uninterruptible power supply which supplies power from another power supply source when a DC power supply stops for some reason, and a power failure for detecting that the power supply from the DC power supply has stopped. Regarding the detection device.

[0002]

2. Description of the Related Art Usually, an uninterruptible power supply that converts the power supplied from a commercial power supply into a direct current and guarantees a direct current output is a power failure by simply detecting the presence or absence of a commercial alternating current before conversion into a direct current. Is easily detected. However,
Direct detection of DC power is required when an uninterruptible power supply is added to the output of the DC power supply, or when a power supply that outputs DC current without converting AC to DC has an uninterruptible power supply. .

Therefore, a method of providing a DC / DC converter at the output of the power supply and supplying power to the load from the DC / DC converter to detect the same as a power supply using a commercial power supply as an input can be considered. However, this configuration has a high reliability but a low efficiency because loss occurs in a normal state where no power failure occurs.

Therefore, in many cases, a voltage detection device for detecting a decrease in output voltage is used as a power failure detection device. FIG. 7 is an explanatory diagram of a conventional power failure detection device. Although the power storage device is composed of the electric double layer capacitor 8 here, any device may be used. Since it is inconvenient for the reference voltage of the comparator that detects the output voltage to fluctuate when the power failure starts, the output of the power storage device that is always stable is used as the reference voltage.

[0005]

When the voltage of the power storage device is composed of a battery different from the voltage of the DC power supply, or when it is composed of an electric double layer capacitor whose voltage fluctuates, a DC / DC converter is used. You need to be prepared. In the above method, since it is necessary to keep the power storage device in the output state as the reference voltage at all times, there is a loss inside the DC / DC converter.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a power failure detection device capable of detecting a power failure in an uninterruptible power supply device without loss.

[0007]

According to the present invention, in an uninterruptible power supply device that guarantees electric power from a DC power supply, loss occurs when the output voltage of the power storage device is output while the power is being supplied from the DC power supply. Therefore, it is not necessary to output the output within the time until it detects that the power supply from the DC power supply has stopped, so that no power loss is detected inside the power storage device. Is provided. According to the present invention, there is provided a power failure detection device characterized in that a capacitor is connected in parallel to the output of a DC power supply and a differentiating circuit for outputting a differential value of the voltage of the capacitor is provided.

Furthermore, the present invention provides a power failure detecting device characterized in that a capacitor is connected in parallel to the output of a DC power source and a comparator is provided for comparing the voltage of the capacitor with the voltage of the DC power source.

That is, according to the present invention, in a power failure detection device in an uninterruptible power supply device that guarantees power supplied from a DC power supply, the power failure detection device includes a capacitor connected to an output of the DC power supply, and a voltage of the capacitor. The power failure detection device is composed of a differentiation circuit that outputs a differential value of and a control circuit.

Further, in the present invention, in the uninterruptible power supply device for ensuring the electric power supplied from the DC power supply, the power failure detection device has a parallel circuit of a capacitor and a first resistance voltage dividing circuit at the output of the DC power supply. Is connected via a first diode, a second resistance voltage divider circuit is also connected to the output of the DC power supply via a second diode, and the voltage at the midpoint of the first resistance voltage divider circuit is And a comparator for comparing the voltage at the midpoint of the second resistance voltage dividing circuit, and a control circuit is further provided.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION A power failure detection device according to an embodiment of the present invention will be described below.

(Embodiment 1) FIG. 1 is an explanatory diagram of a power failure detection device according to Embodiment 1 of the present invention. The power failure detection device of FIG. 1 is a power failure detection device in an uninterruptible power supply that guarantees the power supplied from the DC power supply 1, and includes a capacitor 4a connected to the output of the DC power supply, and a voltage differential of the capacitor 4a. It is composed of a differentiation circuit 5 that outputs a value and a control circuit 7. The differentiating circuit 5 is composed of a capacitor 4b and a resistor 6a.

In the power failure detection device shown in FIG.
Electric double layer capacitor 8 when power supply from
An uninterruptible power supply that supplies electric power from an example will be described in detail.

FIG. 2 is a diagram showing the waveform of the output voltage of the DC power supply in the power failure detection device of FIG. In addition, FIG.
It is a figure which shows the waveform of the output voltage of the differentiating circuit in the power failure detection apparatus of FIG. 2 and 3, region I shows a normal operation state, region II shows a state at the moment when a power failure occurs, and region III shows a state in which power is supplied from the power storage device.

When the power supply from the DC power supply 1 is stopped,
The electric power stored in the capacitor 4a is supplied to the load 2. At this time, the voltage instantaneously drops due to the internal resistance of the capacitor 4a. If the load 2 allows this variation, the operation of the load 2 is performed without interruption. By outputting the differential value of the capacitor voltage at that time by the differentiating circuit 5, it can be detected that the power supply from the DC power supply 1 is stopped.

When it is detected that the power supply from the DC power supply 1 is stopped, the controller 7 turns the switch circuit 10 off.
The power is supplied from the power storage device 3 to N. In this way, the power supply from the electric double layer capacitor 8 occurs only when the power supply from the DC power supply 1 is stopped,
DC is supplied with power from the DC power supply 1.
There is no loss in the / DC converter 9. Since there is a short time from the start of the power failure to the power supply to the power storage device, the capacitance of the capacitor 4a should be as large as possible.

Therefore, it is convenient to use an electric double layer capacitor as the capacitor 4a. If the internal resistance of the capacitor 4a is not sufficient, the resistance may be properly connected in series. Further, here, the differentiation circuit 5
Has a simple configuration in which the capacitor 4b and the resistor 6a are connected in series, but any type such as an operational amplifier may be used.

(Second Embodiment) FIG. 4 is an explanatory diagram of a power failure detection device according to a second embodiment of the present invention. The power failure detection device of FIG. 4 is a power failure detection device in an uninterruptible power supply device that guarantees the power supplied from the DC power supply 1, and the power failure detection device outputs the DC power supply 1 with a capacitor 4c and a first capacitor.
Resistance voltage divider circuit (composed of resistors 6a and 6b)
Is connected in parallel via the first diode 11a, and the output of the DC power supply 1 is also connected to the second resistor voltage dividing circuit (composed of resistors 6d and 6e) and the second diode 11b. A comparator 12 for comparing the midpoint voltage of the first resistance voltage dividing circuit and the midpoint voltage of the second resistance voltage dividing circuit, and a control circuit 7 It has been configured.

Similar to the first embodiment, the uninterruptible power supply for supplying power from the electric double layer capacitor 8 when the power supply from the DC power supply 1 is stopped will be described in detail as an example. FIG. 5 is a diagram showing waveforms of the negative input voltage and the positive input voltage of the comparator 12 in the power failure detection device of FIG. 6 is a diagram showing a waveform of the output voltage of the comparator 12 in the power failure detection device of FIG.

Region I in each figure is the normal operating state,
Area II shows the state at the moment of the power failure, and area III shows the state in which electric power is supplied from the power storage device. When the power supply from the DC power supply 1 is stopped, the voltage of the negative input of the comparator 12 drops, but the voltage of the positive input of the comparator 12 is held by the capacitor 4c. With load 2,
If this variation is allowed, the operation of the load 2 is performed without interruption. The output of the comparator 12 at that time can detect that the power supply from the DC power supply 1 is stopped.

When it is detected that the power supply from the DC power supply 1 is stopped, the controller 7 turns the switch circuit 10 off.
N is set and power is supplied from the power storage device. In this way, the electric power supply from the electric double layer capacitor 8 occurs only when the electric power supply from the DC power supply 1 is stopped, so that the DC / DC converter 9 does not cause a loss in a state without a power failure. The set values of the resistors 6b to 6e must always be larger than the positive input of the comparator 12 when there is no power failure, but there is a little time from the start of the power failure until the power supply to the power storage device 3 is present. , The difference should be as small as possible.

Although the electric double layer capacitor 8 is used as the power storage device 3 here, the power storage device 3 may be of any type. In addition, the control device 7 and the comparator 1
The second power supply may be supplied from the DC power supply 1 as long as it operates in a range in which the output of the DC power supply 1 varies.

[0023]

According to the present invention, it is possible to provide a power failure detection device capable of detecting a power failure of an uninterruptible power supply without loss.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a power failure detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a waveform of an output voltage of a DC power source in the power failure detection device of FIG.

3 is a diagram showing a waveform of an output voltage of a differentiating circuit in the power failure detection device of FIG.

FIG. 4 is an explanatory diagram of a power failure detection device according to a second embodiment of the present invention.

5 is a diagram showing waveforms of a negative input voltage and a positive input voltage of a comparator in the power failure detection device of FIG.

6 is a diagram showing a waveform of an output voltage of a comparator in the power failure detection device of FIG.

FIG. 7 is an explanatory diagram of a conventional power failure detection device.

[Explanation of symbols]

1 DC power supply 2 Load 3 Power storage device 4a, 4b, 4c Capacitor 5 Differentiating circuit 6a, 6b, 6c, 6d, 6e, 6f, 6g, 6h, 6
i resistance 7 control circuit 8 electric double layer capacitor 9 DC / DC converter 10 switch circuits 11a and 11b diode 12 comparator

Claims (2)

[Claims] 1. A power failure detection device for an uninterruptible power supply that guarantees power supplied from a DC power supply, wherein the power failure detection device includes a capacitor connected to an output of the DC power supply,
A differentiating circuit for outputting a differential value of the voltage of the capacitor,
A power failure detection device comprising a control circuit. 2. A power failure detection device for an uninterruptible power supply that guarantees power supplied from a DC power supply, wherein the power failure detection device includes a capacitor and a first resistance voltage divider circuit in parallel at the output of the DC power supply. A circuit is connected via a first diode, and a second resistance voltage divider circuit is also connected to the output of the DC power supply via a second diode. A power failure detection device characterized in that a comparator for comparing the voltage and the voltage at the midpoint of the second resistance voltage dividing circuit is provided, and a control circuit is further provided.