JPH09149643A - Dc power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To utilize various AC input voltages with automatic discrimination by a method wherein an approximately constant DC voltage is supplied to a load connected to a main circuit regardless of the connection of a stepdown transformer. SOLUTION: When the voltage of a commercial power supply 1 is AC 100V, a voltage which is stepped down by a stepdown transformer 2 and rectified and smoothed is applied to voltage dividing resistors 10 and 11, a shunt regulator 18 is turned on in accordance with a ratio between the divided voltages, a control transistor 29 is turned on, a relay contact 23b is closed and, in the positive half cycle period of the AC input of the main circuit, a smoothing capacitor 4 is charged and, in the negative half cycle period, a smoothing capacitor 5 is charged. When the voltage of the commercial power supply 1 is AC 200V, as the rectified and smoothed voltage is doubled, the shunt regulator 18 is turned off, the control transistor 29 is turned off, the relay contact 23b is opened and the smoothing capacitors 4 and 5 which are connected in series are charged. In both the cases, the voltage is full-wave rectified by a load 7 in parallel connection to obtain a required voltage. As a result, a various AC input voltage can be utilized with automatic discrimination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC power supply technique, and more particularly to a technique effectively applied to a DC power supply device or the like that outputs a DC voltage of a predetermined rating from a plurality of types of AC input voltages of different sizes. .

[0002]

2. Description of the Related Art For example, in information processing equipment, direct current power is required for operation of equipment such as semiconductor integrated circuits, and therefore it is almost essential to equip a direct current power source for obtaining direct current power from a commercial alternating current power source. Moreover, the voltage value of the commercial power source is internationally diverse, and in consideration of export and import of equipment, it is possible to provide the DC power source with a function of obtaining a constant DC voltage from various external AC input voltages. desirable.

In an input rectifier circuit for an AC100V / 200V shared power supply, it is common to switch to a double voltage rectification method for a 100V system and a full-wave rectification method for a 200V system to use the same rectified voltage. is there. The circuit operation of this conventional method will be described with reference to FIGS.

FIG. 3 is a circuit diagram showing an example of a possible conventional input voltage switching system using a manual changeover switch. 1 is a commercial AC power supply, 3 is a rectifying diode bridge for input rectification, 4, Reference numeral 5 is a smoothing capacitor such as an aluminum electrolytic capacitor for smoothing the rectified voltage. These two smoothing capacitors 4 and 5 are connected in series and are connected in parallel to the load 7. A switch 26 for manual switching is connected to the AC input terminal 3b of the rectifying diode bridge 3 and the negative terminal of the smoothing capacitor 4. When the voltage of the commercial AC power supply 1 is 100V, the contact of the manual switch 26 is manually closed to charge the smoothing capacitor 4 during the positive half cycle of the AC input, and during the negative half cycle. The smoothing capacitor 5 is charged. As a result, the load 7 connected in parallel to the smoothing capacitors 4 and 5 is supplied with the voltage doubled and rectified.

When the voltage of the commercial AC power source 1 is 200V, the contact of the manual changeover switch 26 is manually opened to serially connect the positive half cycle and the negative half cycle of the AC input. The connected smoothing capacitors 4 and 5 are charged. As a result, the load 7 connected in parallel to the smoothing capacitors 4 and 5 is supplied with the full-wave rectified voltage.

Next, in FIG. 4, a control circuit 28 for detecting the voltage of the commercial AC power supply 1 and turning on / off the triac 27 is provided in place of the input changeover type manual changeover switch illustrated in FIG. FIG. 6 is a circuit diagram of a possible conventional system in which the rectification system is automatically switched.

When the voltage of the commercial AC power supply 1 is 100V, the control circuit 28 detects the voltage of the commercial AC power supply 1 to turn on the triac 27, and the smoothing capacitor is provided during the positive half cycle of the AC input. 4 is charged and the smoothing capacitor 5 is charged during the negative half cycle. As a result, the load 7 connected in parallel to the smoothing capacitors 4 and 5 is supplied with the voltage doubled and rectified.

Further, when the voltage of the commercial AC power source 1 is 200 V, the control circuit 28 detects the voltage of the commercial AC power source 1 and turns off the triac 27 to set a period of a positive half cycle of the AC input. The smoothing capacitors 4 and 5 connected in series are charged during the negative half cycle. As a result, the load 7 connected in parallel to the smoothing capacitors 4 and 5 is supplied with the full-wave rectified voltage.

[0009]

In the conventional method using the manual selector switch, the manual switch must be switched in response to a change in the input voltage, and there is a concern that the load (electronic device) may be damaged due to a switching mistake. is there.

Further, the automatic switching system by turning on / off the triac eliminates the fear of damage to electronic equipment due to switching mistake, but since the failure mode of the triac is short mode, there is a great concern of damage to electronic equipment at the time of failure. There was a technical problem to say. Also, since the commercial AC voltage is rectified as it is and a high DC voltage is output, for example,
It is unsuitable as an input voltage for a DC / DC converter that requires input of a DC low voltage.

An object of the present invention is to provide a DC power supply technology capable of utilizing various AC input voltages by automatically determining the AC input voltage.

Another object of the present invention is to provide a DC power supply technology capable of reliably preventing damage to the equipment at the time of switching mistake or failure.

Still another object of the present invention is to set the DC output to D
It is to provide a DC power supply technology that can be used as an input of a C / DC converter.

[0014]

A DC power supply device of the present invention includes a step-down transformer to which a first AC power supply or a second AC power supply, which has a relationship of a doubled voltage having different voltage values, is connected to a primary side, The main circuit is connected to the secondary side of the step-down transformer and can select full-wave rectification and double-voltage rectification, and the main circuit is full-wave rectified or double-voltage rectified based on the voltage of the primary side or secondary side of the step-down transformer. By switching to rectification,
The configuration includes a rectification voltage switching circuit that outputs a substantially constant DC voltage to the load connected to the main circuit regardless of the connection of the first or second AC power supply having a different voltage to the step-down transformer.

More specifically, for example, AC100V
When using a rectifier circuit including a transformer that can obtain a predetermined voltage when the secondary winding voltage is rectified by a bridge diode rectifier circuit at the time of 200V input in a power supply sharing a system / 200V system, the AC input voltage is monitored, The main circuit is automatically switched to full-wave rectification and voltage doubler rectification circuit by turning on / off the relay connected to the rectification diode bridge of the main circuit by AC input voltage.
/ DC converter is configured to supply a predetermined DC voltage to a load.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a circuit diagram showing an example of the configuration of a DC power supply device according to an embodiment of the present invention, and FIG. 2 is a conceptual diagram showing a part of it. In the present embodiment, as an example, a case will be described in which the present invention is applied to a DC power supply device for both AC100V system / 200V system.

The DC power supply device of this embodiment has a step-down transformer 2 to which a commercial AC power supply 1 is connected on the primary side, and an AC input terminal 3a and an AC input terminal 3b on the secondary side of the step-down transformer 2. The rectifying diode bridge 3 to be connected, the pair of smoothing capacitors 4 and 5 connected in series connected in parallel to the DC output terminal 3c and the DC output terminal 3d of the rectifying diode bridge 3, and the rectifying diode bridge 3 AC input terminal 3
b and a main circuit including a relay 23 (relay internal coil 23a, relay contact 23b, Zener diode 24) for switching the rectification method for opening and closing the connection between the negative terminal (between capacitors) of the smoothing capacitor 4 and this main circuit. The circuit is connected in parallel with the main circuit to the output connector 6 that connects the circuit to the desired load 7 and the secondary side of the step-down transformer 2, and the opening / closing operation of the relay contact 23b is controlled according to the magnitude of the voltage on the secondary side. And a control circuit 25 for monitoring the input voltage.

The step-down transformer 2 is AC2 of the commercial AC power supply 1.
When the voltage of the secondary winding when 00V is input to the primary winding is rectified by the bridge rectification circuit, a predetermined DC voltage (for example, 48V in the present embodiment) is obtained so that the primary side and the secondary side can be obtained. The winding number ratio of the side winding is set. The smoothing capacitor 4 and the smoothing capacitor 5 are composed of, for example, an aluminum electrolytic capacitor or the like.

The control circuit 25 for controlling the opening and closing of the relay contact 23b includes a rectifying diode bridge 8, a smoothing capacitor 9, a voltage dividing resistor 10, a voltage dividing resistor 11, a control resistor 13,
Control resistor 16, control resistor 17, control resistor 19, control resistor 20, control resistor 21, control resistor 30, control transistor 12, control transistor 22, control transistor 29,
It is composed of a backflow prevention diode 14, a capacitor 15, and a shunt regulator 18 for voltage detection. Such a control circuit 25 can be configured by, for example, a hybrid integrated circuit or a monolithic integrated circuit. For this reason, the installation space of the control circuit 25 is small, so that even if it is attached to a part of the main circuit, it is possible to suppress an increase in the installation space of the main circuit.

As shown in FIG. 2, the relay contact 23b
Due to its own elasticity, the open state is maintained in a state where no external force is applied, and when the relay internal coil 23a is excited, the open state is attracted to the closed state. Therefore, in the failure mode such as the disconnection of the relay internal coil 23a, the relay contact 23b is kept open.

An example of the operation of the DC power supply device of this embodiment will be described below.

When the voltage of the commercial AC power supply 1 is AC100V system (first AC power supply), the voltage is once stepped down by the step-down transformer 2 and rectified and smoothed by the rectifying diode bridge 8 and the smoothing capacitor 9 (DC24V). Is a voltage dividing resistor 1
0,11 is applied. The voltage ratio across the voltage dividing resistors 10 and 11 is set to a value at which the shunt regulator 18 turns on when the voltage is 24V. Therefore, AC100
At the time of V, the shunt regulator 18 is turned on by the voltage ratio between the voltage dividing resistors 10 and 11, and the control transistor 1
2, 2 and 22 are turned off, the control transistor 29 is turned on, a current flows through the relay internal coil 23a of the relay 23 to be excited, and the relay contact 23b is turned on (closed) to cause a positive half cycle of the AC input of the main circuit. The smoothing capacitor 4 is charged during the period, and the smoothing capacitor 5 is charged during the negative half cycle period. As a result, the smoothing capacitors 4, 5
In the load 7 connected in parallel with the
A predetermined voltage is supplied to the load 7 such as a DC converter.

The voltage of the commercial AC power supply 1 is AC200.
In the case of the V system (second AC power supply), the voltage once stepped down by the step-down transformer 2 and rectified and smoothed by the rectifying diode bridge 8 and the smoothing capacitor 9 becomes DC48V,
The shunt regulator 18 is turned off by the voltage ratio of the voltage dividing resistors 10 and 11, and the control transistors 12 and 22 are turned on, so that the control transistor 29 is turned off and the relay 2
No current flows through the relay internal coil 23a of No. 3 so that it is not excited, the relay contact 23b is turned off (open), and it is connected in series during the positive half cycle and the negative half cycle of the AC input of the main circuit. The connected smoothing capacitors 4 and 5 are charged. As a result, the load 7 connected in parallel to the smoothing capacitors 4 and 5 undergoes full-wave rectification, and a predetermined voltage is supplied to the load 7 such as a DC / DC converter.

As described above, in the DC power supply device according to the present embodiment, the control circuit 25 for monitoring the input voltage monitors the magnitude of the AC input voltage, and the rectification method of the main circuit is changed to double voltage rectification or full-wave rectification. Automatically and appropriately, the concern about damage to the load 7 of an electronic device or the like due to a mistake in manual switching as in the related art can be eliminated, and commercial power sources of various voltages can be appropriately used. .

Further, as in the prior art, in the automatic switching circuit using a semiconductor switch such as a triac, the failure of the triac is in the short mode. Therefore, when a failure occurs at the time of inputting a high voltage of 200 V, the full-wave is originally intended. What should be rectified is in a voltage doubler rectified state, and a high voltage that is twice the rated voltage is output to the load 7, which may cause damage or malfunction of the electronic device. In the case of a failure such as disconnection of the relay internal coil 23a, the relay contact 23b opens and enters a full-wave rectification state. Therefore, when the input voltage to the primary side of the step-down transformer 2 is 100V / 200V, The DC voltage output to the load 7 does not exceed the rated value, and damage to the equipment is reliably avoided.

Further, since the step-down transformer 2 lowers the voltage from a general commercial AC voltage to a low voltage such as 48 V for rectification, the DC voltage output from the main circuit is directly used as the DC low voltage input. There is also an advantage that it can be supplied as a predetermined input voltage to the load 7 such as a DC / DC converter.

Although the invention made by the present inventor has been specifically described based on the embodiments, the present invention is not limited to the above-described embodiments and can be variously modified without departing from the gist thereof. Needless to say, there is.

For example, the configuration of the control circuit is not limited to that illustrated in the above-mentioned embodiment, but may be any other configuration as long as it can maintain the full-wave rectification mode in the event of a failure or the like. Further, the commercial AC voltage is not limited to AC100 / AC200 as long as it has a voltage doubler relationship, and may have another voltage value.

[0030]

According to the DC power supply device of the present invention, it is possible to utilize various AC input voltages by automatically determining the AC input voltage.

Further, there is an effect that it is possible to surely prevent the equipment from being damaged due to a switching error or a failure.

Further, the effect that the DC output can be used as the input of the DC / DC converter is obtained.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a configuration of a DC power supply device that is an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a part of a DC power supply device according to an embodiment of the present invention.

FIG. 3 is a circuit diagram showing a possible example of a conventional input voltage switching system using a manual selector switch.

FIG. 4 is a circuit diagram showing a possible example of a conventional input voltage switching system using a triac.

[Explanation of symbols]

1 ... Commercial AC power supply, 2 ... Step-down transformer, 3 ... Rectifier diode bridge, 3a, 3b ... AC input terminals, 3c, 3d
... DC output terminals, 4, 5 ... Smoothing capacitor, 6 ... Output connector, 7 ... Load, 8 ... Rectifying diode bridge, 9 ...
Smoothing capacitors, 10, 11 ... Voltage dividing resistors, 14 ... Backflow prevention diodes, 15 ... Capacitors, 13, 16, 1
7, 19, 20, 21, 30 ... Control resistor, 18 ... Shunt regulator, 12, 22, 29 ... Control transistor, 23 ... Relay, 23a ... Relay internal coil (excitation coil), 23b ... Relay contact, 24 ... Zener diode , 25 ... Control circuit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Okawa 1 Horiyamashita, Hadano City, Kanagawa Pref., Inside Hitsuyama Computer Electronics Co., Ltd. (72) Naofumi Kono 810 Shimoimaizumi, Ebina City, Kanagawa Hitachi, Ltd. Office System Division

Claims (3)

[Claims] 1. A step-down transformer connected to a primary side of a first AC power source or a second AC power source having a voltage value that is approximately a double voltage, and a step-down transformer connected to a secondary side of the step-down transformer.
A main circuit capable of selecting full-wave rectification and voltage-doubler rectification, and switching the main circuit to full-wave rectification or voltage-doubler rectification based on the magnitude of the voltage on the primary side or secondary side of the step-down transformer, A rectification voltage switching circuit that outputs a substantially constant DC voltage to a load connected to the main circuit, regardless of the connection of the different first or second AC power supply to the step-down transformer. Power supply. 2. The DC power supply according to claim 1, wherein
The main circuit includes a bridge diode having an AC input terminal connected to the secondary side of the step-down transformer, a pair of smoothing capacitors connected in series with each other, and connected in parallel to a DC output terminal of the bridge diode. And a relay contact for switching connection / disconnection between the connection terminal between the pair of smoothing capacitors and the AC input terminal of the bridge diode, and an exciting coil for closing the relay contact when energized, the rectified voltage The switching circuit includes a control circuit for controlling energization stop and energization of the exciting coil according to the voltage level of the primary side or the secondary side of the step-down transformer. 3. The DC power supply device according to claim 1, wherein the rectified voltage switching circuit comprises a hybrid integrated circuit or a monolithic integrated circuit.