JP3058156B2 - Input disconnect signal sending circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC power supply for supplying predetermined DC power to an electronic device such as a computer.
The present invention relates to an input power supply disconnection signal transmission circuit.

[0002]

2. Description of the Related Art It is necessary to continuously supply AC input power of a power supply device for supplying a predetermined DC power to an electronic device such as a computer. When the AC input power is cut off, the DC voltage of a load is reduced. And the electronic device does not operate normally. 2. Description of the Related Art Conventionally, an input disconnection signal transmission circuit of an AC input power supply for detecting a disconnection of an AC input power supply and stopping processing of the apparatus has monitored the presence or absence of an AC input power supply in the power supply.
When the input power is cut off and the AC input is cut off,
In general, a method of transmitting a disconnection signal to the device side with a predetermined time lag is provided.

[0003]

However, according to the above-mentioned method, the processing of the apparatus is stopped in response to the AC power supply disconnection signal even though the load is light and the output voltage of the power supply is sufficiently maintained. There was a problem that it would be a problem. The problem is to detect only the presence or absence of AC input power inside the power supply, and to determine the state of the load connected to the power supply (the amount of load current).
This is because the disconnection signal is transmitted with a predetermined time lag assuming the maximum load state regardless of the maximum load state.

The present invention has been made under such a background, and an object of the present invention is to provide an input disconnection signal transmission circuit which can prevent transmission of a disconnection signal while an output voltage is held. And

[0005]

According to a first aspect of the present invention, there is provided an input disconnection signal transmitting circuit for notifying an electronic device that an AC input voltage of a power supply device for supplying power to the electronic device has been disconnected. The AC input is rectified by the rectifier
DC voltage value smoothed by the smoothing capacitor
Output capacitor voltage detecting means and the rectifier
Rectified voltage before smoothing detected by photocoupler
The zero-cross detection circuit detects the voltage drop for a predetermined time or less.
AC input that sends AC input disconnect signal when detected above
Disconnection timing detection means and a load current value flowing through the electronic device
Load current detecting means for detecting the
Output voltage and the load current detection.
Output current and the AC input
The disconnection of the AC input voltage is detected by the disconnection timing detecting means.
From the time when the output voltage of the power supply device becomes equal to or less than a predetermined value.
At the load side from this calculated time.
Sends the input disconnect signal when the time required for processing is subtracted
And an input disconnection signal transmission timing calculating means.

[0006]

[0007]

As described above, the feature of the present invention is that
In an input disconnection signal transmission circuit that notifies the load side of the electronic device that the input voltage has been disconnected, detection of the presence or absence of an AC input voltage, the voltage between the terminals of an input smoothing capacitor held by a power supply output, and the power of the load applied to the power supply Is detected and the CPU
It is possible to provide a circuit that predicts the time during which the output is held by calculating with the use of, and prevents transmission of the disconnection signal while the output is held.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an input disconnection signal transmission circuit according to an embodiment of the present invention. A power supply circuit typified by the figure, which rectifies an AC input power supply by a single-phase full-wave rectifier 2 and smoothes it by a smoothing capacitor 3, and supplies a predetermined voltage power to a load 10 by a converter 20, It has an AC input disconnection detection circuit 6 for detecting disconnection. Also,
The current (power) detection circuit 8 converts a current consumed by the load into a voltage by the current transformer 9 and supplies the voltage to the CPU 7. FIG. 2 shows the configuration of the AC input disconnection detection circuit 6.
In this figure, the AC input disconnection detection circuit 6 is, for example, a photocoupler 11 and a zero cross detection circuit 13 in the CPU 7.
It is composed of

Next, the operation of the embodiment of the present invention will be described in detail with reference to the drawings. First, the AC shown in FIG.
The operation of the input disconnection detection circuit 6 will be described. A in FIG.
C input power supply 1 is full-wave rectified by single-phase full-wave rectifier 2 and
(2). When this waveform is detected on the transistor side of the photocoupler, it becomes a rectangular wave shown in (3) of FIG. As shown in FIG. 3, when the AC input is disconnected, the square wave disappears as well. The rectangular wave is detected as a zero cross, and when a state of zero without the rectangular wave has elapsed for a predetermined time T3, it is determined that the power supply has been cut off, and the CPU 7 is notified.

Next, the operation of the circuit of FIG. 1 will be described with reference to FIGS. A at input disconnection detection circuit 6
When the disconnection of the C input power is detected, a signal obtained by converting the voltage of the current detected by the current transformer 9 into a CPU
7, the level is detected by the A / D converter. At the same time, the voltage of the smoothing capacitor 3 is divided by the detection resistor 4 to detect the level. When the AC input power supply 1 is cut off, the output voltage gradually decreases as shown in FIG. 3, but the output voltage holding time T4 usually depends on the current consumption I at the load and the smoothing capacitor 3 of the power supply. Is expressed as follows by the inter-terminal voltage Vc.

As shown in FIG. 3 (4), the voltage between terminals of the smoothing capacitor 3 detected at the time when the AC disconnection is determined is Vc1, and the current value at that time is I. Assuming that the voltage at which the output of the power supply cannot be held is Vc2, the output voltage of the power supply is Vo, and the capacitance of the smoothing capacitor 3 is C, the holding time T4 is T4 = C (Vc1 × Vc1−Vc2 × Vc2) / Vo /
I / 2.

Vc2 and C are values determined at the time of designing the power supply. If predetermined information is written in the CPU 7 in advance, when the AC disconnection is determined, the detected voltage Vc1 and the value of the current I are used. , Perform the above-described calculation in the CPU 7,
The retention time can be estimated. The disconnection signal is transmitted to the load after a time T6 obtained by subtracting the time T5 required for processing on the load from the estimated holding time.

Although the operation of one embodiment of the present invention has been described in detail with reference to the drawings, the present invention is not limited to this embodiment, and a design change or the like may be made without departing from the gist of the present invention. The present invention is also included in the present invention.

[0015]

As described above, the effect obtained by the present invention is to maintain the output of the power supply and to continue the operation of the device without transmitting a disconnection signal as long as the device can operate. Is possible. The reason is A
This is because the disconnection signal is transmitted to the load side by detecting not only the C input but also the state of the DC voltage and the load current on the input side.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an input disconnection signal transmission circuit according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a configuration of an AC input disconnection detection circuit in FIG. 1;

FIG. 3 is a diagram showing waveforms at various parts in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... AC input power supply 2 ... Single-phase full-wave rectifier 3 ... Smoothing capacitor 4 ... Detection resistance 5 ... Rectifier 6 ... AC input disconnection detection circuit 7 ... CPU 8 ... Current (power) detection circuit 9 ... Current transformer 10 ... Load 11 ... Photocoupler 12 ... Zener diode 13 ... Zero cross detection circuit 20 ... Converter

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 3/28 G05F 1/10 304

Claims (1)

(57) [Claims] 1. A power supply unit for supplying power to an electronic device.
An input disconnect signal sending circuit for notifying said electronic device that a C input voltage has been disconnected, wherein an AC input is rectified by a rectifier and is connected to a smoothing capacitor.
Therefore, the capacitor voltage that detects the smoothed DC voltage value
Detecting means for detecting the voltage before smoothing rectified by the rectifier;
And a zero-cross detection circuit detects the voltage drop for a predetermined time or more.
AC input disconnection that sends an AC input disconnection signal when issued
Timing detecting means for detecting a load current value flowing through the electronic device;
Output means and the DC voltage detected by the capacitor voltage detection means.
Voltage value and the load voltage detected by the load current detecting means.
AC input by the flow value and the AC input disconnection timing detecting means
From the time when the disconnection of the voltage is detected, the output of the power supply
The time at which the force voltage falls below the specified value is calculated, and this calculated
When the time required for processing on the load side is subtracted from the
An input disconnection signal transmission timing calculating means for setting a period as an input disconnection signal transmission timing.