JPS63262026A - Ac-dc switching source input voltage monitoring circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an AC-DC switching power supply input voltage monitoring circuit, and in particular to an AC-DC switching power supply input voltage monitoring circuit that has a simplified configuration circuit.
This invention relates to a switching xm input voltage monitoring circuit.

[Conventional technology]

Conventionally, this type of AC-DC switching power supply input voltage monitoring circuit uses a commercial AUVL source 7 as an input power source, and rectifies this input power source with a rectifier circuit 2 including a rectifying element C1l and an input capacitor C, as shown in FIG. Furthermore, in an AC-DC power supply equipped with a DC-DC comparator 6 that converts and outputs a desired DC constant voltage in the form of a switching regulator, after closing the switch 8 and turning on the commercial AC power supply 7, the timer 10 is set. After a period of time has elapsed, the DC-DC converter 6 is started, and the inrush current prevention circuit 1 is configured to short-circuit the inrush current prevention resistor R, which was in a connected state when the commercial AC41 source 7 was turned on, and the commercial ACi source 7 is instantaneously activated. The input voltage is controlled by a momentary power failure detection circuit 12 that detects a so-called instantaneous power failure and outputs a stop signal that notifies the load side of the DC-DC converter 6 that the power supply has stopped, and a rectifier circuit 12 that has a rectifier element CD2. is being monitored.

1. A timer 10 that starts the DC-DC converter 6 and short-circuits the inrush current prevention resistor R of the inrush current prevention circuit 1 through the DC-DC converter when a set time has elapsed, and a rectifier circuit 11. The instantaneous interruption detection circuit 12 plays a main role in monitoring the input power supply.

[Problem that the invention seeks to solve]

The conventional AC-DC switching N and source input voltage monitoring circuit described above sends out a stop signal when a momentary power interruption occurs, regardless of the load size of the DC-DC converter.
Therefore, even when the load is light and there is sufficient margin in the terminal voltage of the input capacitor, that is, the input voltage of the DC-DC converter, a stop signal is sent to the load side every time there is a momentary power outage, which disturbs the normal operation of the load system. There are drawbacks. In addition, there is a drawback that the circuit configuration for monitoring the input voltage has many types including an instantaneous power failure detection circuit, an associated rectifier circuit, and a timer.

The object of the present invention is to eliminate the above-mentioned drawbacks, and to provide an AC-DC system that has a simple configuration and is capable of sending a stop signal for instantaneous power interruption and stopping the supply of power only to loads exceeding a predetermined heavy load.
An object of the present invention is to provide a switching power supply input voltage monitoring circuit.

[Failure to solve the problem]

The circuit of the present invention takes all input power from a commercial AC power source, rectifies it with a rectifying element and an input capacitor, and supplies it to a switching regulator type DC-DC converter.
) An input voltage detection circuit that detects an input voltage of the DC-DC converter applied to the input capacitor in an AC-DC switching power supply input voltage monitoring circuit that monitors an input voltage of an AC-DC switching power supply that is converted into a constant voltage. When the DC-DC converter is activated while receiving the input voltage, and the input power supply is instantaneously cut off when the input voltage exceeds the activation level, the DC-DC converter is activated. 1) C-D C only for the preset heavy load of the DC converter.
a converter operation control circuit that controls the operation of the converter to stop the converter; and a momentary power interruption detection circuit that detects the D(Σ-DC converter) and outputs a stop signal that notifies the instantaneous input power interruption only to a preset heavy load of the Σ-DC converter.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, including an inrush current prevention circuit 1, a rectifier circuit 2. Input voltage detection circuit 3. Converter operation control circuit 4. Momentary interruption detection circuit 5, DC-DC
It is configured with a converter 6. Since the components having the same reference numerals among these components are the same as those of the conventional device shown in FIG. 3, detailed explanations regarding these same components will be omitted.

The input voltage detection circuit 3 detects the voltage across the input capacitor C of the rectifier circuit 2 and supplies it to the converter operation control circuit 4 and the instantaneous interruption detection circuit 5.

Both the converter operation control circuit 4 and the instantaneous interruption detection circuit 5 have basically the same configuration, and each includes a converter 41, a reference voltage generator 42, and a comparator 51 and a reference voltage generator 52.

The reference voltage generators 42, 52 each have D as an initial value.
The starting level of the C-DC converter 6 is used as a reference voltage.

FIG. 2 is an input voltage control characteristic diagram for explaining the input voltage monitoring operation in the embodiment of FIG. 1.

11 shown in Figure 2. ．． 12 shows an example of the input voltage characteristics of the DC-DC converter 6 for heavy load and light load when a momentary power interruption occurs in the power supply from the time the power is turned on. It is captured as the voltage across C.

This input voltage rises when the power is turned on, and the starting level is L.
When it becomes 1, the DC-DC converter 6 is activated. In the converter operation control circuit 4, the initial level value output by the reference voltage generator 42 is set to the starting level L1, and the comparison output that increases as the input voltage increases is converted to DC-D.
While supplying to the C converter 6, the input voltage is at the starting level L.
2 When the magnitude of the human power exceeds 1 and reverses, the output becomes zero and the C-DC converter 6 is activated, and the reference voltage generator 42 receives the output zero information and sets the stop level L3 of the DC-DC converter 6. Generates a voltage of

On the other hand, when the input from the input voltage detection circuit 3 exceeds the activation level L1 and the two-man power level is reversed, the instantaneous power failure detection circuit 5 also outputs zero, and upon receiving this output zero information, the reference voltage generator 52 The output level of is set as the instantaneous interruption detection level L2 as a reference level when detecting an input instantaneous interruption. The comparator 51 does not send out a stop signal until the input level falls below the instantaneous interruption detection level L2 mentioned above.

L2 and L3 shown in FIG. 2 indicate a momentary interruption detection level and a DC-DC converter stop level, respectively.

If a momentary interruption of the input power supply occurs when a heavy load exceeding a preset level is connected to the LDC-DC converter 6, the input voltage will change according to the heavy load characteristic 11, as shown in Figure 2. plummet. When the input voltage reaches the instantaneous interruption detection level L2 indicated by Xl, the comparator 5
The level magnitude relationship of the two-manpower in No. 1 is reversed, and the comparator 51
A stop signal is provided to the heavy load in a predetermined format, and when the input voltage further decreases to the X2 DC-DC converter stop level, the magnitude relationship between the two power levels of the comparator 41 is reversed and the output becomes (, 1-The DC converter 6 is stopped, and the short-circuited state of the inrush current prevention circuit 1 is released and the initial state is returned.

The above is a case of a heavy load, but in the case of a light load, the input voltage drop characteristic due to the occurrence of instantaneous interruption becomes quite gradual, for example, as shown in light load characteristic 7!2.

In this case, the input detection points of the comparators 41 and 51 are respectively X2' and The input voltage recovers to the activation level 1 or above again within a certain time. In this way, when the load is light, it is possible to send a stop signal, control the power supply to avoid stopping the DC-DC converter 6, and send the stop signal, and such operations are more emphasized as the load becomes lighter.

〔Effect of the invention〕

As explained above, according to the present invention, by providing a means for increasing the withstand capacity against instantaneous interruptions as the load of the DC-DCC compal is light, system downtime due to instantaneous interruptions during light loads can be greatly reduced. This has the advantage that it is possible to realize an AC-DC switching power supply input voltage monitoring circuit with a simple configuration in which the input voltage is reduced.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a block diagram of an embodiment of the present invention.
FIG. 3 is an input voltage control characteristic diagram for explaining the input voltage monitoring operation in the embodiment shown in the figure, and FIG. FIG. 2 is a block diagram of a knee DC switching power supply input voltage monitoring circuit. l... Inrush current prevention circuit, 2... Rectifier circuit, 3...
- Input voltage detection circuit, 4... Converter operation control circuit, 5... Momentary interruption detection circuit, 6... DC-DC converter, 7... Commercial AC power supply, 8... Switch, 9...
- Timer, 10... Rectifier circuit, 11... Momentary interruption detection circuit. Agent Patent Attorney Uchihara. Bamboo 1 map MZ country

Claims (1)

[Claims] A switching regulator-type DC power source that uses a commercial AC power source as an input power source and rectifies it with a rectifying element and an input capacitor.
- An AC that monitors the input voltage of the AC-DC switching power supply that supplies the DC converter and converts it to the desired DC constant voltage.
- a DC switching power supply input voltage monitoring circuit, comprising: an input voltage detection circuit that detects an input voltage of the DC-DC converter applied to the input capacitor; and an input voltage detection circuit that starts the DC-DC converter while receiving the input voltage; If an instantaneous input interruption occurs in which the input power source is momentarily cut off when the voltage exceeds the startup level, the DC-DC converter is stopped only for a preset heavy load of the DC-DC converter. a converter operation control circuit for controlling the operation so as to increase the speed of the DC-DC converter; An AC-DC switching power supply input voltage monitoring circuit comprising: a momentary interruption detection circuit that outputs a stop signal that notifies the momentary input interruption only for a preset heavy load of a DC-DC converter.