JPS59136028A - Protecting device for dc stabilized power source - 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 The present invention relates to a protection device for a stabilized DC power supply that prevents a rectifier of the stabilized DC power supply that directly rectifies a commercial AC power supply from being destroyed by rush current or overvoltage.

Conventionally, there is a DC stabilized power supply of this type as shown in FIG. In the figure, 1 is a power switch, and 2 is a rectifier circuit, which includes a protective resistor 2a, a rectifier 2b, and a smoothing capacitor 2c. 3 is a main transformer/transformer drive circuit, 4 is an output smoothing circuit, 5 is an auxiliary power supply circuit, 6 is an overcurrent protection circuit Q control circuit, and 7 is an AC power supply.

The DC stabilized power supply with the above configuration uses a capacitor input type rectifying and smoothing circuit and has a large capacity smoothing capacitor 2C, so when the power switch 1 is turned on, the charging current of the smoothing capacitor 2C, that is, the inrush current A current several ten times the steady current flows. In order to suppress this inrush current, a protective resistor 2a is inserted on the input side of the rectifier 2b, but the inrush current cannot be completely suppressed, and the rectifier 2a
The disadvantage is that it destroys b.

This invention was made in view of the above points. When the power switch is turned on, AC voltage is not immediately supplied to the main power supply side of the DC stabilized power supply, but the auxiliary power circuit is activated, and the auxiliary power supply circuit provides protection. By igniting the triac in the device near zero voltage of the AC voltage, controlling the main power supply so that AC voltage is always supplied from around zero voltage, and suppressing the inrush current to an extremely low level, the rectifier The purpose of the present invention is to provide a protection device for a DC stabilized power supply that prevents destruction. The present invention will be explained below based on the drawings.

FIG. 2 is a block diagram of a protection device for a DC stabilized power supply, which is an embodiment of the present invention. In the figure, 11 is a light emitting element, 12 is a protection circuit for the light receiving element 11, 13 is a light receiving element, 14 is a zero voltage ignition circuit, 15 is a triac,
16 is a surge absorber consisting of a resistor R and a capacitor C. The protection device A is configured as described above. Note that 17 indicates a load, and 5 and 7 are the same as in FIG.

To explain the operation of the protective device A with the above configuration, the terminals ■,
Between (1) and (2), an AC voltage having the waveform shown in FIG. 3(a) is applied from the AC power supply 7 to terminal (2).

When an input signal voltage having a waveform shown in FIG. 3(b) is applied using the auxiliary power supply circuit 5 between 0 and 0, light is emitted from the light emitting element 11, and this light is received by the light receiving element 13. The output of the light receiving element 13 is input to a zero voltage ignition circuit 14.

Until this zero voltage ignition circuit 14 operates, terminals ■,
Although the impedance is high between
A low impedance state exists between terminals ■ and ■. The zero-voltage ignition circuit 14 operates only when the voltage vo of the AC power supply 7 is between the voltages v2 and vl close to 0, and when the output from the light receiving element 13 is applied, and the zero-voltage ignition circuit 14 turns on to apply a load to the load 17. Flow an electric current. When the voltage VO is 72 or more or 1 or less, control is performed to maintain the off state even if the output from the light receiving element 13 is applied. Turn-off occurs when the load current becomes less than the holding current of the torch 15.

In this way, the light receiving element 13 emits light, and by the action of the zero voltage ignition circuit 14, the trigger 15 operates with a delay until the voltage approaches zero. Triac 15 near zero voltage
As a result, the load current shown in FIG. 3(d) flows through the load 17, and the voltage between the terminals (2) and (2) becomes as shown in FIG. 3(C). In other words, the current flowing to the load 17 starts flowing from around the zero voltage of the AC power supply 7, so the current flowing to the load 17
7 can be suppressed to an extremely low level.

FIG. 4 is a diagram showing a state in which the protection device A shown in FIG. 2 is incorporated into a DC stabilized power supply device. That is, the protection device A is inserted in the portion of the protection resistor 2a in the conventional example shown in FIG. 1, and the rest is the same. A circuit including a rectifier 2b, a smoothing capacitor 20, etc. is connected as the load 17 in FIG. 2.

Next, the operation shown in FIG. 4 will be explained.

When the power switch 1 is turned on, the AC voltage from the AC power supply 7 is applied to the auxiliary power supply circuit 5 and the rectification circuit 2. However, since the protection device A cannot operate until the voltage of the auxiliary power supply circuit 5 reaches a constant value, no AC voltage is applied to the rectifier 2b. When the voltage of the auxiliary power supply circuit 5 reaches a certain value, the operating voltage is supplied to the protection device A and the overcurrent protection circuit Q control circuit 6. As a result, the protection device A starts operating, and when the AC power supply voltage becomes near zero, the triac 15 is ignited and an AC voltage having a waveform as shown in FIG. 3(d) is applied to the rectifier 2b. This AC voltage is rectified by the rectifier 2b and applied to the main transformer-transformer drive circuit 3 via the smoothing capacitor 2C.The main transformer transformer drive circuit 3 generates a predetermined voltage, and the output smoothing circuit 4
It can be taken out as an output voltage 4 to the outside through .

A part of the output voltage is applied to an overcurrent protection circuit/control circuit 6 in order to detect an abnormality in the output power supply.

As mentioned above, by inserting the protection device A before the rectifier 2b of the rectifier circuit 2 on the primary side, an AC voltage from around zero voltage is always supplied to the circuit consisting of the rectifier 2b and the smoothing capacitor 20, etc. Therefore, the inrush current can be suppressed to an extremely low level, and destruction of the rectifier 2b can be prevented. Therefore, a rectifier with a low inrush current value can be used.

As explained above, the protection device for a DC stabilized power supply according to the present invention includes an optical coupling element that combines a light emitting element and a light receiving element, a zero voltage ignition circuit operated by the output from this optical coupling element, and a zero voltage ignition circuit operated by the output from this optical coupling element. Since it consists of a triac and a surge absorber that are ignited by a voltage ignition circuit, the input drive voltage range can be widened, for example from TTL level to 10V, and the input drive current can be kept extremely low. Has excellent effects.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional DC stabilized power supply circuit, Figure 2
The figure is a block circuit diagram of a protection device for a DC stabilized power supply which is an embodiment of the present invention, FIG. 3 is an operation waveform diagram for explaining its operation, and FIG. It is a block diagram incorporated into a stabilized power supply circuit. In the figure, 1 is a power switch, 2 is a rectifier circuit, 2b is a rectifier, 2c is a smoothing capacitor, 3 is a main transformer/transformer drive circuit, 4 is an output smoothing circuit, 15 is an auxiliary power supply circuit, and 6 is an overcurrent protection circuit.・Control fl11 circuit, 7 is an AC power supply, 11 is a light emitting element, 12 is a protection circuit, 13 is a light receiving element,
14 is a zero voltage ignition circuit, 15 is a triac, 16 is a surge absorber, and 17 is a load. Figure 1 Figure 3 Figure 1 Figure 4

Claims (1)

[Claims] An optical coupling device combining a light emitting element and a light receiving element, a zero voltage ignition circuit operated by the output from this optical coupling element, a trial array fired by this zero voltage ignition circuit, and a connection to the above-mentioned trigger. A protection device for a DC stabilized power supply, comprising a surge absorber.