JP2924336B2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for equipment such as a pot, a rice cooker, an iron, and a vacuum cleaner, and a power supply in which an electronic circuit used in the equipment is not insulated from a commercial power supply. Things.

[0002]

2. Description of the Related Art In recent years, electric appliances used in homes have become more common with electronic circuits including active elements. When an electronic circuit is mounted on a device, its configuration generally includes a power supply device and other electronic circuits.
Hereinafter, for convenience of description, the commercial power supply will be referred to as a primary circuit. Hereinafter, an example of the power supply of the above-described conventional primary circuit will be described with reference to FIG. Reference numeral 1 denotes a commercial AC power supply, and 19 denotes an auto transformer for adjusting the voltage of the commercial AC power supply 1 to an appropriate level. 20 is a rectifier, 21
Denotes a capacitor, and 12 denotes an electronic circuit serving as a load.

The operation of the conventional power supply device configured as described above will be described. The AC voltage of the commercial AC power supply 1 is dropped by the auto transformer 19. The AC voltage whose voltage has dropped is rectified by the rectifier 20, then smoothed by the capacitor 21, and converted into a DC voltage. The DC voltage obtained at this time is determined by the voltage of the terminal output of the auto transformer 19.

[0004]

However, since the power supply device having the above configuration uses a transformer,
There are problems such as a large amount of materials used, a high cost, a low cost, a heavy, large, inefficient, and a large amount of heat.

The present invention is intended to solve the problems of the conventional method and to realize a power supply device which can be used more easily. It is a first object of the present invention to provide a power supply device in which the fluctuation of the output voltage falls within a certain value even when the power supply fluctuates. A second and third object is to provide second and third means for achieving the first object.

[0006]

According to a first aspect of the present invention, there is provided a rectifier circuit connected to a commercial AC power supply, and a first reference voltage output from the rectifier circuit. A first reference voltage generation circuit that generates, a second reference voltage generation circuit that also generates a second reference voltage from the output of the rectifier circuit, and a capacitor connected in parallel with the load ,
Between the output of the rectifier circuit and the capacitor and load
A first switch circuit for charging the connected capacitor, the first reference voltage generation circuit, and a second reference voltage
Connected to the output of the generator and the first reference voltage generator
When operating, the output voltage of the rectifier circuit and the first reference
The output voltage of the rectifier circuit is compared with the first reference voltage.
In the following cases, the first switch circuit is turned on and the rectifier circuit is turned on.
When the output voltage of the path exceeds the first reference voltage,
A first switch control circuit for turning off the switch circuit, a first current limiting circuit for limiting a current flowing through the first switch circuit, an AC voltage detecting circuit for detecting a fluctuation of a commercial AC power supply voltage, and the AC voltage If the detection circuit
When voltage is detected, the first reference voltage generation circuit and the second
A power supply device includes a second switch circuit for switching a quasi-voltage generation circuit, and a second switch control circuit for receiving the output of the AC voltage detection circuit and controlling the second switch circuit.

According to a second aspect of the present invention, there is provided a rectifier circuit connected to a commercial AC power supply, and a first reference for generating a first reference voltage from an output of the rectifier circuit. A voltage generating circuit, a capacitor connected in parallel with the load, an output of the rectifier circuit, the capacitor and the load.
A first switch circuit for charging the capacitor connected between the first reference circuit and the output voltage of the rectifier circuit and the first reference
The output voltage of the rectifier circuit is compared with the first reference voltage.
In the following cases, the first switch circuit is turned on and the rectifier circuit is turned on.
When the output voltage of the path exceeds the first reference voltage,
A first switch control circuit for turning off the switch circuit, wherein
A first current limiting circuit connected in series to the first switch circuit, for limiting a current flowing through the first switch circuit, an AC voltage detection circuit for detecting a change in commercial AC power supply voltage, and the AC voltage detection circuit When activated, the first current control
Connected in series to the first switch circuit as well as the limit circuit,
A second current limiting circuit for limiting the current flowing through the first switch circuit in preference to the first current limiting circuit; and a third switch.
It is connected to the pitch control circuit, the control and the third switch circuit for switching a first current limiting circuit of the second current limiting circuit, the third switch circuit receiving the output of the AC voltage detection circuit first The power supply device includes three switch control circuits.

According to a third aspect of the present invention, there is provided a rectifier circuit connected to a commercial AC power supply, and a first reference for generating a first reference voltage from an output of the rectifier circuit. A voltage generating circuit, a capacitor connected in parallel with the load, an output of the rectifier circuit, the capacitor and the load.
A first switch circuit for charging the capacitor connected between the first reference circuit and the output voltage of the rectifier circuit and the first reference
The output voltage of the rectifier circuit is compared with the first reference voltage.
In the following cases, the first switch circuit is turned on and the rectifier circuit is turned on.
When the output voltage of the path exceeds the first reference voltage,
A first switch control circuit for turning off the switch circuit, a first current limiting circuit for limiting a current flowing through the <br/> first switch circuit, and the AC voltage detection circuit for detecting a voltage of the commercial AC power source Varies according to the output of the AC voltage detection circuit .
A variable reference voltage generating circuit for generating a variable reference voltage that, prior to
Of the rectifier circuit connected to the output of the
The output voltage of the rectifier circuit is compared with the output voltage and the variable reference voltage.
Is the first switch circuit when is lower than the variable reference voltage
Is turned on, and the output voltage of the rectifier circuit is
And a fourth switch control circuit for turning off the first switch circuit .

[0009]

The first means of the present invention operates as follows. When the commercial AC voltage is higher than the voltage detected by the AC voltage detection circuit and the voltage rectified by the rectification circuit is equal to or lower than the first reference voltage, the first switch control circuit short-circuits the first switch circuit, The capacitor is charged with the current limited by the first current limiting circuit and power is supplied to the load. When the output voltage of the rectifier circuit exceeds the first reference voltage, the first switch control circuit opens the first switch circuit and stops energization. When the commercial AC voltage fluctuates and drops to the voltage detected by the AC voltage detection circuit, the second switch control circuit controls the second switch circuit to switch from the first reference voltage generation circuit to the second reference voltage generation circuit. Switching and power supply or stop by the first reference voltage generation circuit are performed by the second reference voltage generation circuit. In the method of energizing until the voltage of the commercial AC power supply reaches a certain value as in this method, the time required for the AC voltage to reach a certain voltage value increases when the AC voltage decreases. That is, the conduction angle is equivalently increased. Therefore, the amount of power supplied to the load and the capacitor increases, and the output voltage increases. Therefore, when the AC power supply voltage fluctuates and drops, the reference voltage is switched from the first reference voltage to the second reference voltage lower than the first reference voltage, thereby suppressing an increase in the output voltage. In this manner, a power supply device capable of suppressing the fluctuation of the output voltage due to the fluctuation of the AC voltage to a certain value or less is realized.

The second means of the present invention operates as follows. When the AC voltage detected by the AC voltage detection circuit decreases to a certain value, the third switch control circuit operates the third switch circuit to switch the first current limiting circuit to the second current limiting circuit. When the AC voltage becomes equal to or higher than a predetermined value, the operation is switched to the first current limiting circuit again. In this way, the limit current flowing to the load is changed.
Accordingly, it is possible to realize a power supply device capable of suppressing a change in output voltage due to a change in AC voltage to a certain value or less.

[0011] A third aspect of the present invention, when the commercial AC voltage is lowered, a commercial AC power a variable reference voltage variable reference voltage generating circuit receives the output of the second AC voltage detecting circuit generates
To a voltage lower than the first reference voltage according to the degree of pressure drop
Lower continuously. The comparison of this variable reference voltage and the output voltage of the rectifier circuit, when the output voltage of the rectifier circuit is lower than the reference voltage and supplies power to the charging and load of the condenser. When the output voltage of the rectifier circuit becomes higher than the reference voltage, the power supply to the capacitor and the load is stopped. In this way, it is possible to realize a power supply device capable of suppressing the fluctuation of the output voltage due to the fluctuation of the AC voltage to a certain value or less.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply according to a first embodiment of the present invention will be described below with reference to FIG. Reference numeral 1 denotes a commercial AC power supply, and 2 denotes a rectifier circuit connected to the A side of the commercial AC power supply 1. In this embodiment, the rectifier circuit rectifies a positive half-wave. Reference numeral 3 denotes a first current limiting circuit for limiting a current value passing through this line to a certain value or less, and diodes 3a and 3b
And a resistor 3c. First current limiting circuit 3
Works as follows. That is, when a current flows through the base of the transistor constituting the first switch circuit 4 and the first switch circuit 4 conducts, a voltage of about 0.6 V is generated between the base and the emitter. In addition, diodes 3a and 3
A voltage of about 1.8 V is generated in b. Therefore resistor 3
A voltage of 1.2 V is applied to c, and the current flowing through the circuit is limited by the resistance of the resistor 3c. 4 charges the capacitor 5 and supplies the load 12 with power.
This is a first switch circuit for supplying power, and a transistor is used in this embodiment. Reference numeral 5 denotes a capacitor, which obtains a DC output voltage from both ends, and supplies power to the load 12. Reference numeral 6 denotes a first reference voltage generation circuit that generates a first reference voltage. First reference voltage generation circuit 6
Are constant voltage diodes 6a and 6b connected in series between the output terminal A of the rectifier circuit 2 and the terminal B of the commercial AC power supply;
It consists of a resistor 6c. Connection point D of the constant voltage diode 6 b and the resistor 6c, the first reference voltage generating circuit 6
Acts as an output terminal. 7 receives the output of the first reference voltage generation circuit 6 and receives the output of the first switch circuit 4
Is a first switch control circuit for controlling the switch. The first switch control circuit 7 includes a resistor 7a and transistors 7b and 7
and c are connected as follows. The collector of the transistor 7b is connected to the base of the transistor 7c, and the collector of the transistor 7b is connected to the resistor 7a.
The other end of the resistor 7a is the output terminal C of the rectifier circuit 2.
Connected to a point. The emitters of the transistors 7b and 7c are connected to the terminal B of the commercial AC power supply 1. The base of the transistor 7b is connected to the output terminal D of the first reference voltage generating circuit 6, and the collector of the transistor 7c is connected to the base of the transistor constituting the first switch circuit 4. 8 is
This is an AC voltage detection circuit that detects the voltage level of the commercial AC power supply 1. The AC voltage detection circuit 8 includes a constant voltage diode 8
a, a resistor 8b, and a capacitor 8c are connected as follows. Constant voltage diode 8a and resistor 8b
Are connected in series, and the anode at the other end of the constant voltage diode 8 a is connected to the negative terminal of the capacitor 5. The other end of the resistor 8b is connected to the output terminal C of the rectifier circuit 2 . The terminal B of the commercial AC power supply 1 and the negative terminal of the capacitor 5 are the same point. The resistor 8b and the capacitor 8c are connected in parallel. A connection point F between the constant voltage diode 8a, the resistor 8b, and the capacitor 8c is an output terminal of the AC voltage detection circuit 8, and is connected to the second switch control circuit 9. Second switch control circuit 9
Is composed of a transistor 9a and resistors 9b and 9c. The output terminal F of the AC voltage detection circuit 8 is connected to the base of the transistor 9a via a resistor 9c. The collector is connected to one end of the resistor 9b and the second switch circuit 10. The emitter is a rectifier circuit 2
Is connected to the output terminal C of Second switch circuit 10
Is constituted by a transistor in the present embodiment, and the base thereof has a transistor as an output of the second switch control circuit 9.
The collector of the transistor 9a is connected. The collector is connected to the connection point of the constant voltage diodes 6a and 6b of the first reference voltage generation circuit 6, and the emitter is connected to the output terminal C of the rectifier circuit 2. 11 is a second reference voltage generation circuit for generating a second reference voltage,
In the case of the present embodiment, the first reference voltage generating circuit 6 includes a constant voltage diode 6b and a resistor 6c which constitute a part of the first reference voltage generating circuit 6. Reference numeral 12 denotes a load connected to both ends of the capacitor 5, which is usually an electronic circuit.

The operation of this embodiment will be described below. The output peak voltage of the rectifier circuit 2 is determined by the operating voltage of the constant voltage diode 8a forming the AC voltage detecting circuit 8 and the base / emitter of the transistor 9a forming the second switch control circuit 9.
When the voltage is equal to or higher than the sum of the on-state voltages of about 0.6 V, the transistor 9a is turned on. Therefore, a current flows through the resistor 9b, and the voltage between the emitter and the collector of the transistor 9a becomes almost 0V. At this time, the second switch circuit 10 is turned off, and the first reference voltage generating circuit 6 outputs the first reference voltage (hereinafter simply referred to as the first reference voltage) which is the sum of the operating voltages of the constant voltage diodes 6a and 6b. Is created. While the output voltage of the rectifier circuit 2 is 0 and a voltage of a magnitude required to reach the first reference voltage , the output of the first reference voltage generation circuit 6 is 0V . That is, no voltage is generated between both terminals of the resistor 6c. Therefore, the transistor 7b is off, and the transistor 7c is turned on by supplying a bias current to the base by the resistor 7a. Therefore,
A current flows through the base of the transistor constituting the first switch circuit 4 connected to the collector of the transistor 7c. As a result, the first switch circuit 4 is turned on, a current flows from the rectifier circuit 2 to the collector via the emitter of the first switch circuit 4, and the capacitor 5 is charged. At the same time, power is also supplied to the load 12 connected to both ends of the capacitor 5. In this case, the charging current of the capacitor 5 and the current flowing through the load 12 are equal to or less than the value limited by the first current limiting circuit 3. That is, when the first switch circuit 4 is turned on, current also flows through the two diodes 3a and 3b connected in series at the same time.
A voltage of 1.8 V is generated. On the other hand, a voltage of about 0.6 V is generated between the base and the emitter of the transistor 4, and the resistor 3c has a voltage of 1.8 V, which is the sum of the diodes 3a and 3b.
A voltage of about 1.2 V, which is different from V, is applied. Therefore, by appropriately selecting the value of the resistor 3c, the resistor 3c
, In other words, the current flowing through the emitter and collector of the transistor constituting the first switch circuit 4 is limited.

The output voltage of the rectifier circuit 2 rises and exceeds the first reference voltage, and the on-voltage between the base and the emitter of the transistor 7b constituting the first switch control circuit 7 is about 0.1.
When the voltage exceeds 6 V, the transistor 7b turns on, and a current flows to the collector through the resistor 7a. As a result, a voltage is generated in the resistor 7a, and the base-emitter voltage of the transistor 7c becomes almost 0 V,
Is turned off. When the transistor 7c is turned off, the transistor constituting the first switch circuit 4 is turned off because the base current is not supplied. Therefore, no power is supplied to the capacitor 5 and the load 12.

When the output voltage of the rectifier circuit 2 drops again below the ON voltage of the transistor 7b constituting the first switch control circuit 7, the transistor 7b turns off and the transistor 7c turns on. Therefore, the first switch circuit 4 is turned on, and the commercial power is again supplied to the capacitor 5 and the load 12.

Next, the output peak voltage of the rectifier circuit 2 drops by a fixed value, and the constant voltage diode 8 of the AC voltage detection circuit 8
A case will be described below in which the operating voltage of the transistor 9a and the ON voltage of the transistor 9a of the second switch control circuit 9 reach a sum of about 0.6 V or less. The transistor 9a turns off. At this time, the resistor 9b becomes a bias resistor of the transistor of the second switch circuit 10, and turns on the transistor 10. The voltage between the emitter and the collector of the transistor 10 becomes almost 0 V, and the current flows through the constant voltage diode 6b and the resistor 6c. Thereby, the constant voltage diode 6b
And the resistor 6c are equivalent to the second reference voltage generation circuit 11
Will be formed. This second reference voltage generating circuit 1
1 operates in the same manner as the first reference voltage generation circuit 6.

As described above, according to the present embodiment, the voltage of the commercial AC power supply 1 is higher than the voltage detected by the AC voltage detection circuit 8, and the voltage rectified by the rectification circuit 2 is equal to or less than the first reference voltage. , The first switch circuit 4 is short-circuited by the first switch control circuit 7, the capacitor 5 is charged with the current limited by the first current limiting circuit 3, and the load 1
2 is powered. When the output voltage of the rectifier circuit 2 exceeds the first reference voltage, the first switch circuit 4 is opened by the first switch control circuit 7 and charging of the capacitor 5 is stopped. When the voltage of the commercial AC power supply 1 fluctuates and falls to a voltage not detected by the AC voltage detection circuit 8, the second switch control circuit 9 controls the second switch circuit 10,
The first reference voltage generation circuit is switched to the second reference voltage generation circuit, and power supply or stop by the first reference voltage generation circuit is performed by the second reference voltage generation circuit. In this manner, a power supply device capable of suppressing the fluctuation of the output voltage due to the fluctuation of the AC voltage to a certain value or less is realized.

Next, an embodiment of the second means of the present invention will be described with reference to FIG. The same elements as those in the embodiment of the first means are denoted by the same reference numerals, and description thereof will be omitted.
Reference numeral 13 denotes a third switch control circuit, which includes resistors 13a
13c and the transistor 13b are connected as follows. One end of the resistor 13a is connected to the terminal B of the commercial AC power supply, and the other end is connected to the collector of the transistor 13b. The emitter of the transistor 13b is connected to the output terminal C of the rectifier circuit 2. The base is resistor 1
It is connected to the output F of the AC voltage detection circuit 8 via 3b. G is an output point of the third switch control circuit 13, and is a connection point between the resistor 13a and the transistor 13b. 14 receives the output of the third switch control circuit 13,
This is a third switch circuit that switches between the first current limiting circuit 3 and a second current limiting circuit 15 described below. The third switch circuit 14 includes a base connected to the output point G of the third switch control circuit 13, an emitter connected to the output point C of the rectifier circuit 2, and a diode connected to the first current limiting circuit 3 .
3b comprises a transistor having a collector connected to the cathode . Reference numeral 15 denotes a second current limiting circuit, which comprises a diode 3a and a resistor 3c .
The transistors used in this embodiment all have an on-voltage of about 0.6 V, but are ignored for the sake of simplicity. Therefore, when the output voltage of the rectifier circuit 2 reaches the operating voltage of the constant voltage diode 8a of the AC voltage detection circuit 8, the transistor 13b of the third switch control circuit 13 operates.

The operation of the embodiment will be described below. When the commercial AC power supply voltage is higher than the operating voltage of the constant voltage diode 8a constituting the AC voltage detection circuit 8, the transistor 13b of the third switch control circuit 13 is on. As a result, a current flows through the resistor 13a and the transistor 13
The voltage between the emitter and the collector of a becomes almost 0 V, and the third switch circuit 14 is turned off. Therefore, the voltage applied to the resistor 3c is about 1.2 V which is obtained by subtracting the base-emitter voltage of the first switch circuit 4 from the sum of the voltages of the diodes 3a and 3b. That is, in this case, the current flowing through the first switch circuit 4 is limited by the resistance value of the resistor 3c. However, when the voltage of the commercial AC power supply drops due to the voltage fluctuation, the AC voltage detection circuit 8 is turned off, and the transistor 13 of the third switch control circuit 13 is turned off.
b turns off. At this time, the resistor 13a supplies a bias current to the transistor constituting the third switch circuit 14, and the transistor 14 is turned on, so that the emitter-collector voltage becomes almost 0V. Therefore, the voltage applied to the resistor 3c at this time is about 0.6 V obtained by subtracting the base-emitter ON voltage of the transistor constituting the first switch circuit 4 from the voltage of the diode 3a. Therefore resistor 3
The current determined by the value of c, that is, the current determined by the second current limiting circuit is the first switch circuit 4
Will flow. In the present embodiment, the voltage applied to the resistance value of the resistor 3c is equivalent to two diodes when the first current limiting circuit 3 is used, and when the second current limiting circuit 15 is used. Since the current is one stone, the current passing through the first switch circuit 4 when the second current limiting circuit 15 is used is half of the current when the first current limiting circuit 3 is used. Naturally, the diode 3a
Alternatively, a desired limiting current can be adjusted stepwise by changing the number of diodes of the diode 3b.
Note that the AC voltage changes from 0 by the second reference voltage.
Operation is the same as the operation using the first reference voltage.
It is.

According to the present embodiment, when the voltage of the commercial AC power supply detected by the AC voltage detecting circuit 8 is low, the second current limiting circuit 15 is activated prior to the first current limiting circuit 3. This can prevent the output voltage across the capacitor 5 from unnecessarily increasing.

In the embodiment of the first means of the present invention, when the AC power supply voltage fluctuates and decreases, the power supplied to the load and the capacitor increases, and the output voltage increases. According to this point, according to the present embodiment, the current limit of the current limiting circuit is halved, so that the current at the time of energization can be reduced, so that the power to be supplied can be suppressed low, and the increase in the output voltage can be suppressed. Is what you can do. by this,
The voltage rating of the electronic circuit components that make up the power supply and load
This makes it possible to lower the power rating.

Next, an embodiment of the third means of the present invention will be described with reference to FIG. Reference numeral 16 denotes a second AC voltage detection circuit, which is connected to the commercial AC power supply 1 from the output terminal C of the rectifier circuit 2.
The two resistors 16a and 16 connected in series to the B-side terminal of
b and a capacitor 16c connected in parallel with the resistor 16b. With the above configuration, the resistor 16a and the resistor 1
An output proportional to the output voltage of the rectifier circuit 2 is generated from an output point F, which is a connection point of 6b . Reference numeral 17 denotes a variable reference voltage generation circuit which receives an output of the second AC voltage detection circuit 16 and supplies a reference voltage corresponding to the output to a fourth switch control circuit 18. Variable reference voltage generation circuit 17
Is a resistor 17a, a constant voltage diode 17b, and an amplifier 1.
7c are connected as follows. Commercial AC power
The resistor 17a and the constant voltage diode 17b connected in series to the B-side terminal of the source 1 are connected in series, and function as a reference voltage generating circuit. The output of this connection point is connected to the inverting input of amplifier 17c. The non-inverting input side of the amplifier 17c is connected to the output terminal F of the second AC voltage detection circuit 16. Therefore, when the commercial AC voltage increases due to the voltage fluctuation, the output voltage of the variable reference voltage generation circuit 17 increases, and when the commercial AC voltage decreases, the output voltage of the variable reference voltage generation circuit 17 also decreases. The fourth switch control circuit 18 includes a comparator 18a and a transistor 18b. In the comparator 18a, the output of the amplifier 17c is input to the inverting input side, and the output of the rectifier circuit 2 is input to the non-inverting input side. The output of the comparator 18a is connected to the base of the transistor 18b. The emitter of the transistor 18b is connected to the B-side terminal of the commercial AC power supply, and the collector is connected to the collector of the transistor 7b constituting the first switch control circuit 7.

The operation of this embodiment will be described below. AC voltage
Is higher, the variable reference voltage is higher than the first reference voltage.
The apparatus of the present embodiment within one cycle of a commercial AC power supply
Operate with a first reference voltage. Commercial AC power supply
When the pressure fluctuates below a certain value, the variable reference voltage
And the operation within one AC cycle is acceptable.
It is controlled by the variable reference voltage. At this time, the AC voltage drops
Continuously decreases the variable reference voltage depending on the degree of
It will be. The variable reference voltage generation circuit 17 includes the rectifier circuit 2
Second AC voltage detection circuit 16 for detecting the output terminal voltage of
And an operating voltage of the constant voltage diode 17b, and outputs a voltage corresponding to the difference voltage as a reference voltage. That is, since the output of the second AC voltage detection circuit 16 changes according to the output of the rectifier circuit 2, that is, the commercial AC power supply voltage, the reference voltage is a variable reference voltage that varies according to the commercial AC power supply voltage. is there. The fourth switch control circuit 18 is connected to the variable reference voltage generation circuit 17.
The variable reference voltage, which is the output of
Of the output terminal C at the non-inverting input side, and compares the input levels of the two. If the output voltage of the rectifier circuit 2 is higher, the first switch circuit 4 is turned off, and if it is lower, it is turned on. As a result, the amplifier 17c of the variable reference voltage generation circuit 17
By appropriately selecting the amplification degree, the first switch circuit 4 can be repeatedly turned on and off so that the output voltage across the capacitor 5 does not fluctuate with respect to fluctuations in the commercial AC power supply voltage.

As described above, according to this embodiment, the output voltage at both ends of the capacitor 5 is kept constant.

[0025]

As described above, according to the first means of the present invention, when the commercial AC power supply voltage fluctuates in a configuration without using a transformer, the switching reference voltage is adjusted to reduce the fluctuation width of the output voltage. It is intended to realize a power supply device. Further, according to the second means of the present invention, similarly, when the commercial AC power supply voltage fluctuates, a power supply device that adjusts the current supplied to the output to reduce the fluctuation width of the output voltage is realized. . Further, according to the third means of the present invention, it is possible to make the output voltage constant by detecting the commercial AC power supply voltage and setting the reference voltage in accordance with the AC voltage. Therefore, when the power supply device according to the first means of the present invention is used, the components used in the electronic circuit connected to the output of the power supply device can have a low withstand voltage rating and low heat generation. Similarly, the components used by the second means and the third means of the present invention are those which generate less heat and have a lower component rating.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a first means of a power supply device of the present invention.

FIG. 2 is a block diagram showing an embodiment of the second means.

FIG. 3 is a block diagram showing a third embodiment.

FIG. 4 is a block diagram showing a conventional power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Commercial AC power supply 2 Rectifier circuit 3 First current limiting circuit 4 First switch circuit 5 Capacitor 6 First reference voltage generation circuit 7 First switch control circuit 8 AC voltage detection circuit 9 Second switch control circuit 10 Second switch circuit 11 Second reference voltage generation circuit 13 Third switch control circuit 14 Third switch circuit 15 Second current limiting circuit 16 Second AC voltage detection circuit 17 Variable reference voltage generation circuit 18 Fourth Switch control circuit

Claims (3)

(57) [Claims] A rectifier circuit connected to a commercial AC power supply; a first reference voltage generating circuit for generating a first reference voltage from an output of the rectifier circuit; a second reference voltage generating circuit for generating a voltage, negative
A capacitor connected in parallel with the load ;
A first switching circuit for charging the capacitor connected between the output and the capacitor and the load, said first
Output of the reference voltage generating circuit and the second reference voltage generating circuit
When the first reference voltage generation circuit operates
Then, the output voltage of the rectifier circuit is compared with the first reference voltage.
When the output voltage of the rectifier circuit is lower than the first reference voltage
Turn on the first switch circuit, and output voltage of the rectifier circuit
Exceeds the first reference voltage, the first switch circuit
A first switch control circuit for turning off, a first current limiting circuit for limiting a current flowing through the first switch circuit, and the AC voltage detection circuit for detecting the variation of the commercial AC power supply voltage, before
The AC voltage detection circuit has detected an AC voltage below a certain value.
Time, the first reference voltage generation circuit and the second reference voltage generation circuit
A power supply device comprising: a second switch circuit that switches a path; and a second switch control circuit that receives the output of the AC voltage detection circuit and controls the second switch circuit. 2. A rectifier circuit connected to a commercial AC power supply, a first reference voltage generator circuit for generating a first reference voltage from an output of the rectifier circuit, and a capacitor connected in parallel with a load. > The output of the rectifier circuit and the capacitor and load
A first switch circuit for charging the capacitor connected between the first rectifier circuit and the output voltage of the rectifier circuit and the first base circuit.
The reference voltage is compared with the first reference voltage.
When the pressure is equal to or less than the pressure, the first switch circuit is turned on, and rectification is performed.
When the output voltage of the circuit exceeds a first reference voltage, the first
A first switch control circuit for turning off the switching circuit, before
The first switch circuit connected in series with the first switch circuit, a first current limiting circuit that limits a current flowing through the first switch circuit, an AC voltage detection circuit that detects a change in commercial AC power supply voltage,
When the AC voltage detection circuit operates, the first current
Connected in series with the first switch circuit
Is, a second current limiting circuit for limiting a current flowing through the first switch circuit in preference to the first current limiting circuit, a third
A third switch circuit connected to the switch control circuit and switching between the first current limiting circuit and the second current limiting circuit,
A power supply device comprising the third switch control circuit for controlling a third switch circuit in response to an output of the AC voltage detection circuit. 3. A rectifier connected to a commercial AC power supply, a first reference voltage generator for generating a first reference voltage from an output of the rectifier, and a capacitor connected in parallel with a load. > The output of the rectifier circuit and the capacitor and load
A first switch circuit for charging the capacitor connected between the first rectifier circuit and the output voltage of the rectifier circuit and the first base circuit.
The reference voltage is compared with the first reference voltage.
When the pressure is equal to or less than the pressure, the first switch circuit is turned on, and rectification is performed.
When the output voltage of the circuit exceeds a first reference voltage, the first
A first switch control circuit for turning off the switching circuit, before
A first current limiting circuit that limits a current flowing through the first switch circuit, an AC voltage detecting circuit that detects a voltage of a commercial AC power supply, and a voltage that varies according to an output of the AC voltage detecting circuit.
A variable reference voltage generating circuit for generating a variable reference voltage
A rectifier circuit connected to the output of the variable reference voltage generation circuit
The output voltage of the rectifier circuit is compared with the output voltage of
When the voltage is lower than the variable reference voltage, the first switch
The rectifier circuit output voltage is higher than the variable reference voltage.
And a fourth switch control circuit that turns off the first switch circuit .