JPH11285255A - Power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power circuit which does not require high bleakdown voltage element to be used and is suitable for miniaturization. SOLUTION: When one of AC powers of two different voltage values is inputted, a changeover circuit 3 is closed to constitute a voltage doubler rectifier circuit, and when the other AC power is inputted, a changeover circuit 4 is opened to constitute a bridge rectifier circuit, so that two kinds of the AC powers are converted into a DC voltage V0 of a roughly the same value and is outputted. A first diode 51 of an auxiliary power circuit 5 constitutes a circuit for charging a third capacitor 53 in the positive half period of the AC powers. A second diode 52 constitutes a circuit for impressing the AC powers to the series circuit of the third and fourth capacitors 53, 54 in the negative half period. A terminal voltage Vcc of the fourth capacitor 54 is used as the operating voltage of the control circuit 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
For AC input of V and AC 200V, switch to double voltage rectification for the former and full-wave rectification for the latter, and obtain DC output of almost the same value for two different AC power supply systems. Power supply circuit.

[0002]

2. Description of the Related Art In a power supply circuit of this type, when switching between a voltage doubler rectifier circuit and a full-wave rectifier circuit, it is possible to manually operate a changeover switch. As a workaround,
A mainstream circuit configuration automatically switches to full-wave rectification and voltage doubler rectification according to the difference in commercial power supply. JP-A-62-178173, JP-A-60-27916 and JP-A-3-145926 disclose such automatic switching technology.

In order to perform automatic switching, an AC input voltage is detected, and based on the detection signal, an operating voltage is supplied to the control circuit together with a control circuit for controlling a switching circuit including a three-terminal switch element such as a triac. An auxiliary power supply circuit is required.

In configuring the auxiliary power supply circuit, Japanese Patent Laid-Open No. 62-178173 and Japanese Patent Laid-Open No.
In Japanese Patent No. 5926, the AC input voltage is full-wave rectified or half-wave rectified. However, if the AC input is, for example, AC
Since switching between 200 V and 100 V AC is performed, a high withstand voltage element that can withstand the peak value at 200 V AC must be used as the passive circuit component and the active circuit component constituting the control circuit, which increases the cost.

In Japanese Patent Application Laid-Open No. 60-27916, an AC input voltage is reduced by using a transformer, and an auxiliary power supply is generated by using the reduced voltage. But,
In this case, the size of the circuit is increased and the number of components is increased, and it is impossible to meet the demand for downsizing.

[0006]

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a power supply circuit which does not require the use of a high withstand voltage element as a component of a control circuit and which is suitable for downsizing the circuit configuration. It is.

[0007]

In order to solve the above-described problems, a power supply circuit according to the present invention includes a diode bridge circuit, a capacitor circuit, a switching circuit, a control circuit, and an auxiliary power supply circuit. Are selectively inputted, and the two types of AC power are converted into DC voltages having substantially the same value and output.

[0008] The diode bridge circuit has an AC input terminal and a rectified output terminal. The capacitor circuit includes at least a first capacitor and a second capacitor, and the first capacitor and the second capacitor are connected in series between rectified output terminals of the diode bridge circuit.

The switching circuit is closed when one AC power supply is input to form a voltage doubler rectifier circuit by the diode bridge circuit, and is opened when the other AC power supply is input and is a full-wave rectifier circuit by the diode bridge circuit. Is connected between one of the AC input terminals of the diode bridge circuit and a connection point between the first capacitor and the second capacitor.

In the above configuration, the AC power supply is, for example, A
In the case where AC100V is selected between C100V and AC200V, the switching circuit is opened when AC200V is selected. Then, the AC input of AC 200 V is full-wave rectified by the full-wave rectifier circuit, the rectified output is smoothed by the first capacitor and the second capacitor, and a DC voltage corresponding to AC 200 V is obtained between the DC lines.

When 100 VAC is selected as the AC power supply, the switching circuit is closed. Then, in the positive cycle, AC 100 V is rectified through one of the diodes constituting the full-wave rectifier circuit, and the rectified output is smoothed by the first capacitor. At this time, the terminal voltage of the first capacitor is a DC voltage corresponding to AC 100V. On the other hand, during the negative cycle, AC 100 V is rectified through another diode constituting the full-wave rectifier circuit, and the rectified output is smoothed by the second capacitor. At this time, the terminal voltage of the second capacitor is AC
It becomes a DC voltage corresponding to 100V. Between the DC lines, a doubled DC voltage obtained by superimposing the terminal voltage in the positive cycle and the terminal voltage in the negative cycle is obtained.

The power supply circuit according to the present invention further includes a control circuit and an auxiliary power supply circuit. The control circuit controls the switching circuit in response to a voltage value of an AC power supply. Therefore, the circuit configuration can be automatically switched to full-wave rectification and voltage doubler rectification according to the difference between commercial power supplies such as AC100V and AC200V.

[0013] The auxiliary power supply circuit generates an operating voltage for the control circuit and supplies it to the control circuit. The auxiliary power supply circuit includes a first diode, a second diode, a third capacitor, and a fourth capacitor. The first diode, for example, in the positive half cycle of the AC power supply,
A circuit for charging the third capacitor with the AC power supply is configured. Therefore, the third capacitor is charged in the positive half cycle.

Next, the second diode constitutes a circuit for applying AC power to a series circuit of the third capacitor and the fourth capacitor in the negative half cycle of the AC power. Then, the terminal voltage of the fourth capacitor is used as the operating voltage of the control circuit.

In this auxiliary power supply circuit, the terminal voltage of the fourth capacitor 54 used as the operating voltage of the control circuit is determined by the capacitance value of the third capacitor and the input impedance of the control circuit connected in parallel with the third capacitor. Determined in relation. Therefore, by appropriately selecting the capacitance value of the third capacitor and the input impedance of the control circuit 4, the fourth
Can be set to a low voltage. Therefore, it is not necessary to use a high breakdown voltage element as the passive circuit component and the active circuit component to which the terminal voltage of the fourth capacitor is applied. Further, the terminal voltage of the fourth capacitor is determined by the input impedance of the control circuit. Therefore, by making the input impedance Z of the control circuit different between the AC100 system and the AC200V system, the fourth terminal voltage can be set to a value that is substantially the same in both systems.

Moreover, since the circuit configuration is composed of rectifier diodes and capacitors, the circuit configuration is significantly reduced in size and the number of parts is reduced as compared with the case where a transformer is used.

The power supply circuit according to the present invention is applicable not only to a power supply that takes an independent form itself such as a switching power supply, but also to a power supply that does not take an independent form such as a power supply section of various electronic devices. Widely applicable.

[0018]

FIG. 1 is an electric circuit connection diagram of a power supply circuit according to the present invention. The power supply circuit according to the present invention includes a diode bridge circuit 1, a capacitor circuit 2, a switching circuit 3, a control circuit 4, and an auxiliary power supply circuit 5, and two types of AC power supplies 6 having different voltage values, for example, AC100V. And A
C200V is selectively input, converts these two types of AC power supplies 6 into DC voltages Vo of substantially the same value, and outputs them. This DC voltage Vo is supplied to the load 7. A typical example of the load 7 is a switching power supply. The switching power supply includes not only an independent power supply but also a power supply that does not take an independent form such as a power supply unit of various electronic devices.

The diode bridge circuit 1 has AC input terminals a and b and rectification output terminals c and d. The capacitor circuit 2 includes at least a first capacitor 21 and a second capacitor 22. The first capacitor 21 and the second capacitor 22 are connected in series between the rectification output terminals cd of the diode bridge circuit 1. ing.

The switching circuit 3 is closed when one of the AC power supplies 6 is input to form a voltage doubler rectifier circuit by the diode bridge circuit 1, and is opened when the other AC power supply 6 is input and is full-wave by the diode bridge circuit 1. An AC input terminal b of the diode bridge circuit 1 and a first capacitor 21 and a second capacitor 22 so that a rectifier circuit is formed.
And the connection point e. The illustrated switching circuit 3 includes a bidirectional three-terminal switch element such as a triac, and has a circuit configuration in which a trigger signal from the control circuit 4 is supplied to the gate of the bidirectional three-terminal switch element.

In the above configuration, when the AC power supply 6 is selected between, for example, AC 100 V and AC 200 V, when the AC 200 V is selected, the switching circuit 3 is opened by the gate trigger signal supplied from the control circuit 4. Is done. Then, the AC input of AC 200 V is full-wave rectified by the diode bridge circuit 1, the rectified output is smoothed by the first capacitor 21 and the second capacitor 22, and the DC voltage V 0 corresponding to AC 200 V is applied between the DC lines. can get.

When AC 100 V is selected as the AC power supply 6, the switching circuit 3 is closed. Then, in the positive cycle, AC 100 V is rectified through one of the diodes constituting the diode bridge circuit 1, and the rectified output is smoothed by the first capacitor 21. At this time, the terminal voltage of the first capacitor 21 is AC100
DC voltage corresponding to V. On the other hand, during a negative cycle, AC 100 V is rectified through another diode constituting the diode bridge circuit 1, and the rectified output is smoothed by the second capacitor 22. At this time,
The terminal voltage of the second capacitor 22 is a DC voltage corresponding to AC 100V. Between the DC lines, a doubled DC voltage V0 obtained by superposing the terminal voltage in the positive cycle and the terminal voltage in the negative cycle is obtained.

The power supply circuit according to the present invention further includes a control circuit 4 and an auxiliary power supply circuit 5. The control circuit 4 controls the switching circuit 3 in response to the voltage value of the AC power supply 6.
Therefore, the circuit configuration can be automatically switched to full-wave rectification and voltage doubler rectification according to the difference between commercial power supplies such as AC100V and AC200V.

The auxiliary power supply circuit 5 generates an operating voltage for the control circuit 4 and supplies it to the control circuit 4. This auxiliary power supply circuit 5 includes a first diode 51, a second diode 52, a third capacitor 53, and a fourth capacitor 54. As shown in FIG. 2, the first diode 51 is a circuit IC that charges the third capacitor 53 with the AC power supply 6 in, for example, a positive half cycle of the AC power supply 6.
1. Therefore, the third capacitor 53 is charged in the positive half cycle.

Next, as shown in FIG. 3, the second diode 52 is connected to the series circuit of the third capacitor 53 and the fourth capacitor 54 in the negative half cycle of the AC power supply 6.
The circuit IC2 for applying the AC power supply 6 is configured. And
The terminal voltage Vcc of the fourth capacitor 54 is
It is used as the operating voltage of

In the auxiliary power supply circuit 5, the control circuit 4
The terminal voltage Vcc of the fourth capacitor 54 used as the operating voltage of the third capacitor 53 is related to the capacitance value C1 of the third capacitor 53 and the input impedance Z of the control circuit 4 connected in parallel to the fourth capacitor 54. Is determined by the equation

(Vcc) ² = (1/4) · (C1) · (Vac) ² · f · Z where Vac is the AC power supply voltage f is the AC power supply frequency Z is the input impedance of the control circuit 4 By appropriately selecting the capacitance value C1 of the capacitor 53 and the input impedance Z of the control circuit 4, the terminal voltage Vcc of the capacitor 54 can be set to a low voltage of 63 V or less. Therefore, as the first rectifier diode 51 and the second rectifier diode 52,
There is no need to use a device with a high breakdown voltage. This point will be described with a specific example. For example, if C1 = 0.1 μF Vac = 265 V f = 50 Hz Z = 10 kΩ, Vcc = 29.6 V.

Further, as understood from the above equation, the fourth
The terminal voltage Vcc of the capacitor 54 is determined by the input impedance Z of the control circuit 4. Therefore, AC100
By making the input impedance Z of the control circuit 4 different between the system and the AC 200 V system, the fourth terminal voltage Vcc can be set to a value substantially equal to or less than 63 V in both systems, for example. . When the terminal voltage Vcc of the fourth capacitor 54 is set to 63 V or less, a passive circuit element constituting the control circuit 4 and an active circuit element such as a semiconductor element having a withstand voltage of 80 V can be used. Such a low-withstand-voltage electronic component is less expensive (for example, half-value) than a circuit component exceeding a withstand voltage of 80 V.
Therefore, the cost of the control circuit 4 can be significantly reduced, and further, the cost of the power supply circuit can be reduced.

In addition, the first rectifier diode 51, the second rectifier diode 52, the third capacitor 53, and the fourth capacitor 54 have a circuit configuration, so that the circuit configuration is significantly smaller than when a transformer is used. And the number of parts is reduced.

FIG. 4 is an electric circuit diagram showing another embodiment of the power supply circuit according to the present invention. The same components as those of the embodiment shown in FIG. 1 are denoted by the same reference numerals. Also in this embodiment, the auxiliary power supply circuit 5
A first diode 51, a second diode 52, a third capacitor 53, and a fourth capacitor 54 are included. As shown in FIG. 5, the first diode 51 constitutes a circuit IC1 for charging the third capacitor 53 by the AC power supply 6 in, for example, a negative half cycle of the AC power supply 6. Therefore, the third capacitor 53 is charged in the negative half cycle.

Next, as shown in FIG. 6, the second diode 52 is connected to the series circuit of the third capacitor 53 and the fourth capacitor 54 in the positive half cycle of the AC power supply 6.
The circuit IC2 for applying the AC power supply 6 is configured. And
The terminal voltage Vcc of the fourth capacitor 54 is
It is used as the operating voltage of

FIG. 7 shows a specific example of a control circuit included in the power supply circuit according to the present invention. The control circuit 4
It includes a first transistor T1, a second transistor T2, and a third transistor T3.

The base of the first transistor T1 is connected to one of the AC power supply lines through a series circuit of a Zener diode D1 and resistors R1 and R2, and is connected to the other of the AC power supply lines through a resistor Ro. Resistance Ro
R3 is a voltage dividing resistor for dividing the AC power supply voltage Vac.

The base of the first transistor T1 is connected to one end of a fourth capacitor 54 through a resistor R3. A diode D2 is connected in parallel to the resistor R3. The collector of the first transistor T1 is connected to the collector of the third transistor T3 via the resistor R4. The emitter of the first transistor T1 is connected to the emitter of the third transistor T3,
It is led to one end of the fourth capacitor 54.

The second transistor T2 has a collector
The capacitor C1 is connected to one end of the fourth capacitor 54, and the emitter is connected to one end of the resistor R6. The other end of the resistor R6 is connected to the other end of the fourth capacitor 54. A resistor R5 is connected in parallel to the capacitor C1. A parallel circuit of a resistor R7 and a capacitor C2 is connected between the base and the emitter of the second transistor T2. Further, the second transistor T
2 and a capacitor C1 connected to the collector
The capacitor C3 is connected to one end of the capacitor C3.

The third transistor T3 has a collector connected to one end of a resistor R6 via a capacitor C2.

The emitter of the second transistor T2 has
A series circuit of a bidirectional breakover semiconductor element 8 and a resistor R8 is connected. This series circuit is a switching circuit 3
Are connected to the gate of the bidirectional three-terminal element. A parallel circuit of a resistor R9 and a capacitor C4 is connected to the gate circuit of the bidirectional three-terminal element.

In the above circuit, the AC power supply 6
When the voltage is 00 V, the Zener diode D1 has a resistance R
It conducts by the voltage divided by o to R3. When the Zener diode D1 conducts, the first transistor T1 turns on.

When the first transistor T1 is turned on,
Since the base of the second transistor T2 is driven, the second transistor T2 is turned on. When the second transistor T2 turns on, the third transistor T3 turns on, and the terminal voltage of the capacitor C3 becomes almost zero.
For this reason, the voltage applied to both ends of the bidirectional breakover type semiconductor element 8 becomes extremely low, the bidirectional breakover type semiconductor element 8 is turned off, and the three-terminal switch element forming the switching circuit is turned off. Thus, the above-described full-wave rectification is performed.

When the second transistor T2 is turned on,
Since the third transistor T3 is turned on and the second transistor T2 is driven, the self-holding operation starts. 4th
Of the capacitor 54 is consumed by the resistor R6.

When the AC power supply 6 is 100 V AC,
Since the Zener diode D1 does not conduct, the above operation by the first transistor T1 to the third transistor T3 is not performed. When the AC power supply 6 is AC100V,
The capacitor C3 is charged through the diode 51 or 52 and the resistor R6. When the charging terminal voltage of the capacitor C3 reaches the breakover voltage of the semiconductor element 8 due to this charging action, the semiconductor element 8 performs a breakover operation. The gate of the three-terminal switch element forming the switching circuit 3 is triggered by the breakover operation of the semiconductor element 8, and the three-terminal switch element is turned on. As a result, the voltage doubler rectification described above is performed.

The power consumed at this time is
3 and the resistance R6. Thus, AC10
By switching the input impedance of the control circuit 4 between the 0 system and the 200 V AC system, the voltage of the fourth capacitor 54 can be set to 63 V or less.

[0043]

As described above, according to the present invention, it is not necessary to use an element having a high withstand voltage, and it is possible to provide a power supply circuit suitable for downsizing the circuit configuration.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram of a power supply circuit according to the present invention.

FIG. 2 is an electric circuit diagram for explaining the operation of the power supply circuit shown in FIG.

FIG. 3 is an electric circuit diagram for explaining another operation of the power supply circuit shown in FIG. 1;

FIG. 4 is an electric circuit diagram showing another embodiment of the power supply circuit according to the present invention.

FIG. 5 is an electric circuit diagram for explaining the operation of the power supply circuit shown in FIG.

6 is an electric circuit diagram illustrating another operation of the power supply circuit shown in FIG.

FIG. 7 is an electric circuit diagram showing another embodiment of the power supply circuit according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 diode bridge circuit 2 capacitor circuit 21 first capacitor 22 second capacitor 3 switching circuit 4 control circuit 5 auxiliary power supply circuit 51 first diode 52 second diode 53 third capacitor 54 fourth capacitor

Claims (2)

[Claims] 1. An AC power supply including a diode bridge circuit, a capacitor circuit, a switching circuit, a control circuit, and an auxiliary power supply circuit. A power supply circuit that converts a power supply into a DC voltage having substantially the same value and outputs the DC voltage, wherein the diode bridge circuit has an AC input terminal and a rectification output terminal, and the capacitor circuit includes at least a first capacitor and A second capacitor, wherein the first capacitor and the second capacitor are connected in series between rectified output terminals of the diode bridge circuit; and the switching circuit is closed when one of the AC power supplies is input. To form a voltage doubler rectifier circuit by the diode bridge circuit. An AC power supply connected between one of the AC input terminals of the diode bridge circuit and a connection point between the first capacitor and the second capacitor so that a current circuit is formed. Controlling the switching circuit in response to the voltage value of (i), wherein the auxiliary power supply circuit is a circuit that generates an operating voltage for the control circuit and supplies the operating voltage to the control circuit,
, A second diode, a third capacitor, and a fourth capacitor, wherein the first diode is connected to the third capacitor by the AC power supply during one half cycle of the AC power supply. The second diode constitutes a circuit for applying the AC power to a series circuit of the third capacitor and the fourth capacitor in another half cycle of the AC power. And a power supply circuit in which a terminal voltage of the fourth capacitor is used as an operating voltage of the control circuit. 2. The power supply circuit according to claim 1, wherein a terminal voltage of the fourth capacitor is set to 63 V or less.