JPH07163147A - Rectifying/smoothing circuit - Google Patents

Abstract

PURPOSE:To increase resistance against momentary power interruption in the case of low voltage without increasing the mounting area by providing a switch which connects first and second electrolytic capacitors in parallel for low voltage AC commercial power supply and in series for high voltage AC commercial power supply. CONSTITUTION:In the case of 100V AC commercial power supply, first and second switches 14, 15 are turned ON whereas a third switch 16 is turned OFF thus connecting first and second electrolytic capacitors 12, 13 in parallel. In case of 200V AC commercial power supply, the first to third switches 14, 15, 16 are turned OFF. When the third switch 16 is turned ON, a circuit 17 blocks surge current flowing into the second electrolytic capacitor 13. This circuitry increases the resistance against momentary power interruption of 100V system by switching the switches 14, 15, 16 depending on the voltage of AC commercial power supply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifying / smoothing circuit which uses a commercial AC power supply having a different voltage as a power source, rectifies and smoothes each commercial AC power to convert it into DC power, and supplies the DC power to an electronic device. In particular, the present invention relates to a rectifying / smoothing circuit configured to increase a momentary stop proof strength when a commercial AC power supply stops instantaneously.

[0002]

2. Description of the Related Art In a conventional rectifying / smoothing circuit of a worldwide power supply that can be used in commercial AC power supplies in various countries, when the commercial AC power supply is momentarily stopped in ms order due to an external factor such as lightning surge, an electrolytic capacitor is used. The stored DC power is used as a momentary stopping resistance to continue driving electronic devices.

The momentary stopping proof strength is defined as W = 1/2 CV ² , and is proportional to the capacitance C of the electrolytic capacitor and the square of the voltage V applied to the electrolytic capacitor.
In the case of V system, the momentary stop proof is 200V for commercial AC power supply.
It is lower than that of the system.

Therefore, it is necessary to increase the overall capacity C of the electrolytic capacitor in order to improve the momentary stopping resistance when the commercial AC power source is a 100 V system. There is no other way to increase the quantity or capacity. Therefore, the mounting area of the electrolytic capacitor is also large.

A specific configuration of a conventional rectifying / smoothing circuit will be described below with reference to the drawings.

FIG. 2 is a circuit diagram showing a conventional rectifying / smoothing circuit. This rectifying / smoothing circuit includes a bridge diode 21 for full-wave rectifying a commercial AC power supply, electrolytic capacitors 22, 23 connected in series for smoothing the full-wave rectified power and storing it as DC power, and a commercial AC power supply. Is 100V
It is composed of a switch 24 for switching between the case of the system and the case of the 200V system. One end of the switch 24 is connected to a common connection point of both electrolytic capacitors 22 and 23.

The operation of the rectifying / smoothing circuit configured as above will be described. When the commercial AC power supply is a 100V system, the switch 24 is turned on and one electrolytic capacitor 23 is short-circuited. The commercial AC power supply is full-wave rectified by the full-wave rectification bridge diode 21, and after that, the switch 24 is turned on, so that the DC power is stored only in the electrolytic capacitor 22. The reason why the switch 24 is turned on in the 100V system is to increase the momentary stopping resistance proportional to the capacity of the electrolytic capacitor.

Further, when the commercial AC power source is a 200V system, in order to reduce the voltage applied to each electrolytic capacitor,
By turning off the switch 24, both electrolytic capacitors 2
DC power will be stored in Nos. 2 and 23.

As described above, when the commercial AC power supply is of 100V system, the DC power is stored only in the electrolytic capacitor 22, so that the momentary stopping resistance is lower than that of the commercial AC power supply of 200V system.

[0010]

As described above, in the conventional rectifying / smoothing circuit having the above-mentioned structure, when the commercial AC power supply is a 100V system, the momentary stopping resistance is the capacity of the electrolytic capacitor and the voltage applied to the electrolytic capacitor. Depends on
Compared to the case where the commercial AC power supply is a 200V system, the momentary stop proof strength becomes lower. In order to increase the momentary stopping resistance, it is necessary to use a large-capacity electrolytic capacitor. Therefore, the rectifying and smoothing circuit has a large mounting area.

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and an object of the present invention is to provide a rectifying / smoothing circuit capable of increasing the momentary stopping resistance when the commercial AC power source is instantaneously stopped.

[0012]

In order to achieve this object, a rectifying / smoothing circuit of the present invention comprises a rectifying diode and first and second electrolytic cells respectively connected in series to the rectifying diode. And a group of switches for connecting the electrolytic capacitors in parallel when the commercial AC power source has a low voltage and for connecting the electrolytic capacitors in series when the commercial AC power source has a high voltage. It is what

It also has a rush current prevention circuit for preventing a rush current flowing when the switch is turned on.

[0014]

With this configuration, when the commercial AC power supply has a low voltage, it is possible to increase the momentary stop proof strength, and since it is not necessary to increase the capacity or number of electrolytic capacitors to increase the momentary stop proof strength. Also, the mounting area can be reduced.

[0015]

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

FIG. 1 is a circuit diagram showing a rectifying / smoothing circuit according to an embodiment of the present invention. In FIG. 1, 11 is 100V
System, full-wave rectification bridge diode for full-wave rectification of 200V commercial AC power supply, 12 is a first electrolytic capacitor, 1
3 is a second electrolytic capacitor, 14 is a first switch, 1
Reference numeral 5 is a second switch, 16 is a third switch, and 17 is an inrush current prevention circuit.

A full-wave rectification bridge diode 11 is connected to a high-potential-side power supply line on the secondary side of the AC line filter, and the first electrolytic capacitor 12 and the first switch 14 are connected in series to the full-wave rectification bridge diode 11. The circuit is connected. The series circuit of the second switch 15, the inrush current prevention circuit 17, and the second electrolytic capacitor 13 is the first circuit.
Are connected in parallel to the series circuit of the electrolytic capacitor 12 and the first switch 14. A third switch 16 is inserted between the connection point between the first electrolytic capacitor 12 and the first switch 14 and the connection point between the second switch 15 and the inrush current prevention circuit 17. The capacitances of the first electrolytic capacitor 12 and the second electrolytic capacitor 13 are equal to each other, and this is designated as C.

The operation of the rectifying / smoothing circuit configured as described above will be described. When the commercial AC power supply is a 100V system, the first switch 14 is turned on, the second switch 15 is turned on, and the third switch 16 is turned off to set the capacitance of the electrolytic capacitor to 2C for the entire rectifying and smoothing circuit. As a result, the instantaneous stop proof strength can be increased to twice that of the conventional rectifying and smoothing circuit.

When the commercial AC power source is a 200V system, the first switch 14 is turned off, the second switch 15 is turned off, and the third switch 16 is turned on. As a result, the instantaneous stopping strength of the rectifying / smoothing circuit is the same as that of the conventional rectifying / smoothing circuit.

Further, when the third switch 16 is turned on, the inrush current prevention circuit 17 causes the second charge with a small amount of charge.
It is possible to prevent the inrush current flowing through the electrolytic capacitor 13 of FIG.

As described above, according to this embodiment, the instantaneous stop proof strength can be increased and the instantaneous stop proof strength can be increased when the commercial AC power source is 100 V system by switching the switch depending on the commercial AC power source. Since it is not necessary to increase the capacity and the number of electrolytic capacitors for increasing the number, the mounting area can be reduced.

[0022]

As described above, according to the present invention, the instantaneous stop proof strength can be increased by switching the switch even when the commercial AC power supply is different. Therefore, even when the commercial AC power supply is not supplied for a long time, it is increased. Since a constant DC power can be supplied to the electronic device within the momentary stopping resistance, the electronic device can be normally operated.

Since it is not necessary to use a large capacity electrolytic capacitor, the mounting area can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a rectifying / smoothing circuit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a conventional rectifying / smoothing circuit.

[Explanation of symbols]

 11 ... Full wave rectification bridge diode 12 ... First electrolytic capacitor 13 ... Second electrolytic capacitor 14 ... First switch 15 ... Second switch 16 ... Third switch 17 ... Inrush current Prevention circuit

Claims (2)

[Claims] 1. A rectifying diode, first and second electrolytic capacitors respectively connected in series to the rectifying diode, and both electrolytic capacitors connected in parallel when a commercial AC power source has a low voltage. And a group of switches for setting both the electrolytic capacitors in series when the commercial AC power supply is at a high voltage. 2. The rectifying / smoothing circuit according to claim 1, further comprising an inrush current prevention circuit for preventing an inrush current flowing when the switch is turned on.