JP2893982B2 - 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 device for a device such as a pot, a rice cooker, an iron and a vacuum cleaner, and a power supply device in which an electronic circuit used in the device 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 circuit 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. 1 is a commercial AC power supply,
Reference numeral 20 denotes an automatic transformer for adjusting the voltage of the commercial AC power supply 1 to an appropriate level. Reference numeral 21 denotes a rectifier, 22 denotes a capacitor, and 10 denotes an electronic circuit serving as a load.

The operation of the conventional power supply circuit configured as described above will be described. The AC voltage of the commercial AC power supply 1 is dropped by the auto transformer 20. The AC voltage whose voltage has dropped is rectified by the rectifier 21 and then smoothed by the capacitor 22 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 20.

[0004]

However, since the power supply circuit 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.

An object of the present invention is to solve the problems of the conventional method and to realize a power supply device which can be more easily used. The first purpose is a configuration that does not use a transformer, and charges the capacitor with the power of the AC power supply until the voltage reaches a certain value, stops the power supply when the voltage exceeds a certain value, and keeps the output voltage rise constant. An object of the present invention is to provide a power supply device that can be suppressed to a value or less. A second, third, and fourth object is to provide second, third, and fourth 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 first switch control circuit that receives an output of the first reference voltage generation circuit and controls on / off of the first switch circuit, and a current that flows through the first switch circuit. A first current limiting circuit for limiting, a capacitor charged by the first switch circuit, an output voltage detection circuit for detecting an output voltage between both ends of the capacitor, and receiving the output of the output voltage detection circuit, The power supply device includes a second switch control circuit for controlling the first switch control 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 generation circuit, a first switch control circuit that receives an output of the first reference voltage generation circuit and controls on / off of the first switch circuit, and a first current that limits a current flowing through the first switch circuit A limiting circuit, a capacitor charged by the first switch circuit, an output voltage detection circuit for detecting an output voltage across the capacitor, and a first reference voltage generation circuit when the output voltage detection circuit operates. A second reference voltage generation circuit that generates a second reference voltage from the output of the rectifier circuit by priority, a second switch circuit that switches between the first reference voltage generation circuit and the second reference voltage generation circuit, Receiving the output of the serial output voltage detection circuit in which a second power supply having a third switch control circuit for controlling the switch circuit.

[0008] A third means of the present invention for achieving the third object is a rectifier circuit connected to a commercial AC power supply,
A first reference voltage generation circuit that generates a first reference voltage from an output of the rectifier circuit; and a first switch control that receives an output of the first reference voltage generation circuit and controls on / off of a first switch circuit. Circuit, a first current limiting circuit that limits the current flowing through the first switch circuit, a capacitor charged by the first switch circuit, and an output voltage detection circuit that detects an output voltage across the capacitor. A second current limiting circuit that limits the current flowing through the first switch circuit in preference to the first current limiting circuit when the output voltage detection circuit operates, a first current limiting circuit, and a second current limiting circuit. The power supply device includes a third switch circuit that switches a current limiting circuit, and a fourth switch control circuit that receives an output of the output voltage detection circuit and controls the third switch circuit. .

According to a fourth aspect of the present invention, there is provided a rectifier circuit connected to a commercial AC power supply.
A first reference voltage generation circuit that generates a first reference voltage from an output of the rectifier circuit; and a first switch control that receives an output of the first reference voltage generation circuit and controls on / off of a first switch circuit. Circuit, a first current limiting circuit that limits the current flowing through the first switch circuit, a capacitor charged by the first switch circuit, and an output voltage detection circuit that detects an output voltage across the capacitor. A variable reference voltage generation circuit that receives an output of the output voltage detection circuit and generates a variable reference voltage corresponding to the output of the first switch circuit; The power supply device includes a fifth switch control circuit that controls the first switch circuit prior to the first switch control circuit.

[0010]

The first means of the present invention is to control the first switch control when the output voltage is lower than the voltage detected by the output voltage detection circuit and the voltage rectified by the rectification circuit is lower than the first reference voltage. The circuit short-circuits the first switch circuit, charges the capacitor with the current limited by the first current limiting circuit, and supplies power 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 output voltage rises to the voltage detected by the output voltage detection circuit, the second switch control circuit controls the first switch circuit so that the output voltage does not rise above the detection voltage detected by the previous output voltage detection circuit Is what you do. Thus, when the output voltage reaches a certain value, the power supply is stopped, and a power supply circuit capable of suppressing the output voltage to a certain value or less is realized.

The second means of the present invention operates as follows. When the output voltage detected by the output voltage detecting means rises to a certain value, the third switch control circuit activates the second switch circuit to change the first reference voltage generation circuit to the second reference voltage generation circuit. Switching, the first switch circuit is operated by the second reference voltage generated by the second reference voltage generation circuit and the first switch control circuit. When the output voltage falls below a certain value, the third switch control circuit activates the second switch circuit to switch from the second reference voltage generation circuit to the first reference voltage generation circuit, and the first reference voltage The first switch circuit is controlled by a first reference voltage generated by a generation circuit and a first switch control circuit.

The third means of the present invention is that when the output voltage detected by the output voltage detecting means reaches a predetermined value, the fourth switch control circuit activates the third switch circuit to cause the first current limiting circuit to operate. To the second current limiting circuit.
When the output voltage falls below a certain value, the operation is switched to the first current limiting circuit again.

According to a fourth aspect of the present invention, when the output voltage rises, the reference voltage generated by the variable reference voltage generating circuit in response to the output of the output voltage detecting means decreases. Increase the reference voltage. This reference voltage is compared with the output voltage of the rectifier circuit, and when the output voltage of the rectifier circuit is lower than the reference voltage, charging of the capacitor and power supply to the load are performed. 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. Thus, the operation is performed so that the output voltage becomes constant.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A power supply circuit according to an embodiment of the first means 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 is a positive half-wave rectifier circuit. 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 comprises a diode 3a and a resistor 3b. Reference numeral 4 denotes a first switch circuit for turning on / off the power supply to the output side. In this embodiment, a transistor is used. The first current limiting circuit operates as follows. That is, when the base current of the transistor 4 flows and the transistor 4 becomes conductive, about 0.6
A voltage of V is generated, and a voltage of about 1.2 V is generated in the diode 3a. Therefore, a voltage of 0.6 V is applied to the resistor 3b, and the current flowing is limited by the value of the resistor 3b. Reference numeral 5 denotes a capacitor which obtains a DC output voltage from both ends. Reference numeral 6 denotes a first reference voltage generation circuit that generates a first reference voltage. The first reference voltage generation circuit 6 includes a constant voltage diode 6a and a resistor 6b connected in series from the output terminal A of the rectifier circuit to the terminal B of the other commercial power supply. The voltage at the connection point D of the two is the output terminal of the first reference voltage generation circuit 1. Reference numeral 7 denotes a first switch control circuit that receives the output of the first reference voltage generation circuit 6 and controls the first switch circuit 4.
The first switch control circuit 7 includes a resistor 7a and transistors 7b and 7c. The connection configuration includes the collector of the transistor 7b and the base of the transistor 7c,
The collector of the transistor 7b is connected to the resistor 7a, and the other end of the resistor 7a is connected to a point C which is an output terminal of the rectifier circuit 2. The emitters of the transistors 7b and 7c are connected to the B-side terminal of the commercial power supply. The base of the transistor 7b is connected to the output terminal D of the first reference voltage generating circuit 6,
The collector of c is connected to the base of the transistor 4 constituting the first switch circuit. Reference numeral 8 denotes an output voltage detection circuit that detects a DC voltage between both ends of the capacitor 5. The output voltage detection circuit 8 includes a constant voltage diode 8a
And a resistor 8b. The constant voltage diode 8a and the resistor 8b are connected in series.
Is connected to the positive terminal of the capacitor 5. The other end of the resistor 8b is a terminal B of a commercial power supply.
It is connected to the. Terminal B of commercial power supply and capacitor 5
Are the same points. Constant voltage diode 8a
A connection point F between the output voltage detection circuit 8 and the resistor 8b is connected to the second switch control circuit 9. In the present embodiment, the second switch control circuit 9 is constituted by a transistor, and the base thereof is connected to the output terminal F of the output voltage detection circuit 8. The collector is connected to the collector of the transistor 7b of the first switch control circuit 7. The emitter is connected to a B-side terminal of a commercial power supply. Reference numeral 10 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. From the time when the output voltage of the rectifier circuit 2 reaches 0 to the first reference voltage (hereinafter simply referred to as the first reference voltage) which is the operating voltage of the constant voltage diode 6a constituting the first reference voltage generation circuit 6. During this time, the first reference voltage generation circuit 6 does not operate. That is, no voltage is generated between both terminals of the resistor 6b. 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, and current flows from the rectifier circuit 2 to the collector via the emitter of the first switch circuit 4,
The capacitor 5 is charged. At the same time, power is also supplied to the load 10 connected to both ends of the capacitor 5. In this case, the charging current of the capacitor 5 and the current flowing to the load 10 become 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 connected in series at the same time, and a voltage of about 1.2 V is generated during this time. 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 3b has a voltage of 1.2 V of the diode 3a.
, A voltage of about 0.6 V is applied. Therefore, by appropriately selecting the value of the resistor 3b, the current flowing through the resistor 3b, in other words, the current flowing through the transistor forming the first switch circuit 4 is limited.
When the output voltage of the rectifier circuit 2 rises and exceeds the first reference voltage, and exceeds the base-emitter ON voltage of the transistor 7b constituting the first switch control circuit 7, approximately 0.6 V, the transistor 7b turns on. Then, a current flows to the collector through the resistor 7a. As a result, a voltage is generated in the resistor 7a, the voltage between the base and the emitter of the transistor 7c becomes substantially 0 V, and the transistor 7c 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 10. 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 10.

Here, the operation when the output voltage detecting circuit 8 and the second switch control circuit 9 operating in response to the output voltage detecting circuit 8 are provided in the power supply circuit will be described. When the load 10 fluctuates and the load current decreases, the voltage applied to the load, that is, the voltage across the capacitor 5 increases. This increase increases as the amount of decrease in the load current increases. The output voltage detection circuit 8 monitors the output voltage across the capacitor 5. While the output voltage is lower than the operating voltage of the constant voltage diode 8a, the resistor 8b is not energized, so that no voltage is generated at both ends. Therefore, the transistor constituting the second switch control circuit 9 is off, and the first switch circuit 4 is continuously controlled by the first switch control circuit 7. If the output voltage exceeds the operating voltage of the constant voltage diode 8a,
This operating voltage is generated between both terminals of the resistor a.
The remaining voltage is generated between the terminals b. When the voltage between both ends of the resistor 8b exceeds the base-emitter on-voltage of the transistor 9 constituting the second switch control circuit 9, the transistor constituting the second switch control circuit 9 is turned on. The first switch control circuit is operated prior to the first reference voltage generation circuit. Thus, the first switch circuit 4 is turned off, and the power supply to the capacitor 5 and the load 10 is stopped.

Therefore, the dynamic operation of this embodiment is as follows. The first switch circuit 4 is on until the voltage rectified by the rectifier circuit 2 gradually increases from 0 V and reaches the first reference voltage of the first reference voltage generation circuit 7. During this time, the voltage across the capacitor 5 increases. When the output voltage across the capacitor 5 reaches the sum of the operating voltage of the constant voltage diode 8a forming the output voltage detecting circuit 8 and the ON voltage of the transistor forming the second switch control circuit 9,
The second switch control circuit 9 operates to turn off the first switch circuit 4 prior to the first reference voltage generation circuit 6. When the first switch circuit 4 is turned off, the output voltage of the capacitor 5 decreases. When the output voltage of the capacitor 5 decreases, the output voltage detection circuit 8 stops detecting this output voltage. When the detection is stopped, the second switch control circuit 9
Is turned off, and the first switch circuit 4 is turned on by the first reference voltage generation circuit 6 and the first switch control circuit 7. When the first switch circuit 4 is turned on, the output voltage across the capacitor 5 starts to increase. Hereinafter, as described above, the first switch circuit is connected to the sum of the operating voltage of the constant voltage diode 8a forming the output voltage detecting circuit 8 and the operating voltage of the transistor 9 forming the second switch control circuit. Repeats on and off.

When the output voltage of the rectifier circuit 2 exceeds the first reference voltage and the transistor 7b constituting the first switch control circuit 7 is turned on, the first switch circuit 4 is turned off and the output of the capacitor 5 and the load 10 The power supply is stopped.
When the output voltage of the rectifier circuit 2 drops beyond its peak and drops again to the sum of the first reference voltage and the operating voltage of the transistor 7b, the transistor 7b turns off and the first switch control circuit 7 turning on the first switch circuit 4 acts. That is, power is supplied to the load 10 while charging the capacitor 5. In this way, the second switch control circuit 9 is turned on and off in the same manner as described above with the output voltage of the capacitor 5 as a boundary with the voltage obtained by the output voltage detection circuit 8.

As described above, in the present embodiment, the output voltage detection circuit 8 is used before the output of the rectifier circuit 2 reaches the first reference voltage.
When the output voltage reaches the level at which the output voltage is detected, the second switch control circuit 9 functions to control the first switch circuit 4 prior to the first reference voltage generation circuit 6. When the output voltage of the rectifier circuit 2 reaches the first reference voltage, the first switch circuit 4 is turned off by the first switch control circuit 7. The output voltage is output voltage detection circuit 8
, The operation of the second switch control circuit 9 stops, and only the first switch control circuit 7 operates to control the first switch circuit 4. In this manner, a power supply device capable of suppressing an increase in output voltage to a certain value or less can be provided.

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 11 denotes a third switch control circuit, which has a resistor 11a and a transistor 11b. One end of the resistor 11a is connected to the output terminal C of the rectifier circuit 2 and the other end is connected to the transistor 11
b is connected to the collector. The emitter of the transistor 11b is connected to the B-side terminal of the commercial power supply. The base is connected to the output of the output voltage detection circuit 8. 12 receives the output of the third switch control circuit 11,
A second switch circuit that switches between the second reference voltage generation circuit 13 and the first reference voltage generation circuit 6. The second reference voltage, which is the operating voltage of the constant voltage diode 13a constituting the second reference voltage generation circuit 13, is set to a value lower than the first reference voltage of the first reference voltage generation circuit 6. And

The operation of this embodiment will be described below. The transistor 11b constituting the third switch control circuit 11 is approximately
Although it has an ON voltage of 0.6 V, it is ignored for the sake of simplicity. When the output voltage of the rectifier circuit 2 is low, that is, when the output voltage is located between 0 V and the first reference voltage, the first switch control circuit 7 operates to short-circuit the first switch circuit 4, and the capacitors 5 and Power is supplied to the load 10. In this case, when the load current is small and the output voltage across the capacitor 5 is high, the output voltage detection circuit 8 may be used before the output voltage of the rectifier circuit 2 reaches the first reference voltage.
May reach the operating voltage of the constant voltage diode 8a first. In this case, the present embodiment operates as follows. That is, when the output voltage at both ends of the capacitor 5 reaches the operating voltage of the constant voltage diode 8a forming the output voltage detecting circuit 8, the transistor 11b forming the third switch control circuit 11 is turned on and the resistor 11a Voltage is generated at both ends. As a result, an on-voltage is generated between the base and the emitter of the transistor constituting the second switch circuit 12, and the second switch circuit 12 is turned on, and the voltage between the emitter and the collector of this transistor becomes almost 0V. Thus, current flows through the second reference voltage generation circuit 13 including the constant voltage diode 13a and the resistor 6b, and the constant voltage diode 13a generates a second reference voltage. Since the second reference voltage is set lower than the first reference voltage, the second reference voltage generation circuit 13 uses the first reference voltage until the output voltage of the rectifier circuit 2 reaches the first reference voltage. The switch control circuit 7 is controlled. Then, when the output voltage of the rectifier circuit 2 reaches the first reference voltage, the first reference voltage generation circuit 6 operates to turn on the transistor 7b constituting the first switch control circuit 7. When the transistor 7b is turned on, the transistor 7c is turned off,
Therefore, the first switch circuit 4 turns off. When the first switch circuit 4 is turned off, power is not supplied to the capacitor 5 and the load 10. When power is not supplied, the load 10 is supplied with the electric charge charged in the capacitor 5.

Thereafter, when the output voltage of the rectifier circuit 2 falls after passing the peak, power is supplied to the condenser 5 and the load 10 of the commercial power supply as follows. When the output voltage of the rectifier circuit 2 drops to the first reference voltage,
The first switch circuit 4 is turned on to charge the capacitor 5 and supply power to the load 10. When the output voltage at both ends of the capacitor 5 exceeds the voltage detected by the output voltage detection circuit 8, the first switch control circuit 7 is again operated by the second reference voltage generation circuit 13. That is, the first switch circuit 4 is turned on and off when the output voltage at both ends of the capacitor 5 is detected by the output detection circuit 8. In other words, when the load current is small and the output voltage is about to rise, the first switch control circuit 6 operates at the second reference voltage, so that the operating voltage is reduced, so that the power supply is reduced and the output is more than necessary. Do not increase the voltage.

Next, when the first reference voltage is reached before reaching the operating voltage of the output voltage detecting circuit 8 when the load current is large and the output voltage is low, the output detecting circuit 8 and the third switch The control circuit 11, the second switch circuit 12, and the second reference voltage generation circuit 13 do not operate. That is, when the load current is large, the first switch control circuit 7 operates at the first reference voltage, so that the operating voltage is increased, the power supplied to the capacitor 5 and the load 10 is increased, and the required voltage is secured.

FIG. 3 is a block diagram showing an embodiment of the third means of the present invention. Reference numeral 14 denotes a fourth switch control circuit, which includes a resistor 14a and a transistor 14b. The output of the output voltage detecting circuit 8 is connected to the base of the transistor 14b, and a resistor 14a and the collector and the emitter of the transistor 14b are connected in series between the output terminal C of the rectifier circuit 2 and the other terminal B of the commercial power supply. Are connected. The output of the fourth switch control circuit 14 is a connection point G between the resistor 14a and the collector of the transistor 14b. Reference numeral 15 denotes a third switch circuit which receives the output of the output point G of the fourth switch control circuit 14 and switches between the second current limit circuit 16 and the first current limit circuit 3 described below. The third switch circuit 15 is connected to the base connected to the output point G of the fourth switch control circuit 14, the emitter connected to the output point C of the rectifier circuit 2, and connected to the first current limiting circuit 3. PN with collector
It is composed of P transistors. Reference numeral 16 denotes a second current limiting circuit, which includes a diode 16a and the first current limiting circuit 3.

The operation of this embodiment will be described below. When the output voltage at both ends of the capacitor 5 is lower than the operating voltage of the constant voltage diode 8a constituting the output voltage detection circuit 8, the transistor 14b of the fourth switch control circuit 14 is off. Therefore , no current flows through the resistor 14a, and the transistor of the third switch circuit 15 is off . The voltage applied to the resistor vessel 3b and slave Tsu <br/> the diode 16a
About minus from the voltage of the sum of the diode 3a of the first switch circuit 4 based, the emitter voltage of about 0.6V
1.2V is applied. Therefore , the current flowing through the first switch circuit 4 is limited by the resistance value of the resistor 3b . When the output voltage across the load current decreases and the capacitor 5 is increased, the output detection circuit 8 is operated, the transistor 14b of the fourth switch control circuit 14 is turned on. Thus, a voltage is generated at both ends of the resistor 14a, and the transistor constituting the third switch circuit 15 is turned on . Third
When the switch circuit 15 is turned on, the collector and the emitter
The voltage between them is almost 0V. Therefore, the voltage applied to the resistor 3b is changed from the voltage of the diode 3a to the first switch.
Between the base and the emitter of the transistor constituting the switch circuit 4.
It is about 0.6 V obtained by subtracting the ON voltage of about 0.6 V. Therefore, the current determined by the value of the resistor 3b, ie,
The current determined by the first current limiting circuit flows through the first switch circuit 4. In this embodiment, the voltage applied to the resistance value of the resistor 3b is equivalent to one diode when the first current limiting circuit is used, and the second current limiting voltage including the first current limiting circuit is used. When the circuit is used, the current is equal to two, so the current passing through the first switch circuit 4 when the second current limiting circuit is used is twice as large as that when the first current limiting circuit is used. Become. As a matter of course, by changing the number of diodes 3a or 16a, it is possible to gradually adjust the current to a desired limit current.

According to the present embodiment, when the load current is small, it is detected that the output voltage generated at both ends of the capacitor 5 is increased, and the second current limiting circuit 3 is given priority over the first current limiting circuit 3. By operating the circuit 16, the output voltage at both ends of the capacitor 5 can be prevented from rising more than necessary.

Next, an embodiment of the fourth means of the present invention will be described with reference to FIG. Reference numeral 17 denotes a second output voltage detection circuit, which connects two resistors 17a and 17b in series. Reference numeral 18 denotes a variable reference voltage generation circuit which receives an output of the second output voltage detection circuit 17 and supplies a reference voltage corresponding to the output to a fifth switch control circuit 19. The variable reference voltage generation circuit 18 includes a resistor 18a, a constant voltage diode 18b, and an amplifier 18c.
Resistor 18a and constant voltage diode 18 connected in series
b serves as a reference voltage generating circuit, and the output of the connection point is connected to the non-inverting input of the amplifier 18c. The inverting input side of the amplifier 18c is connected to the second output voltage detection circuit 1
7 output terminal. The fifth switch control circuit 19 includes a comparator 19a and a transistor 19b. The comparator 19a is connected to the amplifier 18c.
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 19a is connected to the base of the transistor 19b. The emitter of the transistor 19b is connected to the B-side terminal of the commercial 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. The variable reference voltage generation circuit 18 operates with the voltage of the difference between the output of the second output voltage detection circuit 17 that detects the output voltage across the capacitor 5 and the operating voltage of the constant voltage diode 18b,
A voltage corresponding to the difference voltage is output as a reference voltage.
That is, since the output of the second output voltage detection circuit changes according to the output voltage across the capacitor 5, the reference voltage is a variable reference voltage that varies according to the output voltage across the capacitor 5. . The fifth switch control circuit 19 receives the variable reference voltage output from the variable reference voltage generation circuit 18 on the inverting input side, receives the voltage of the output terminal C of the rectifier circuit 2 on the non-inverting input side, and receives the input levels of both. Compare. 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 first switch circuit 4 repeatedly turns on and off so that the output voltage across the capacitor 5 does not fluctuate.

As described above, according to the present embodiment, the output voltage across the capacitor 5 is kept constant.

In the embodiment of the second means of the present invention and the embodiment of the third means of the present invention, by inserting a capacitor in parallel with the resistor 8b of the output voltage detecting circuit 8, the output voltage can be reduced. The third switch control circuit and the fourth switch control circuit can be operated by giving a time constant to the fluctuation. Also, by connecting a capacitor in parallel to the resistor 17b of the second output voltage detecting means 17 of the fourth means embodiment of the present invention, a time constant is provided for the output voltage fluctuation, and the fifth switch control is performed. It is also possible to make the circuit operate.

[0031]

According to the first means of the present invention, an easy-to-use power supply device is realized without using a transformer. The output voltage is detected more than necessary by detecting the output voltage and controlling the energizing switch. Can be prevented from rising
Withstand voltage, heat generation, etc. of parts can be suppressed. Further, according to the second means of the present invention, by detecting the output voltage and changing the reference voltage of the switch control circuit, when the output voltage rises by a certain value, the voltage rise is suppressed further, and the parts to be used are rated to withstand voltage. And the heat generation of used parts can be suppressed. Further, when the output voltage decreases by a certain value, it is possible to suppress a further decrease in the output voltage and obtain a required voltage even when the load current increases. Further, according to the third means of the present invention, the effect of the second invention is realized by limiting the current value of the flowing current.
Further, according to the fourth aspect of the present invention, it is possible to make the output voltage constant by detecting the output voltage and setting the reference voltage according to the output voltage. This has the same effect as described above.

[Brief description of the drawings]

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

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

FIG. 3 is a block diagram showing an embodiment of the third means.

FIG. 4 is a block diagram showing an embodiment of the fourth means.

FIG. 5 is a block diagram showing a conventional power supply device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 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 output voltage detection circuit 9 second switch control circuit 11 Third switch control circuit 12 Second switch circuit 13 Second reference voltage generating circuit 14 Fourth switch control circuit 15 Third switch circuit 16 Second current limiting circuit 17 Second output voltage detecting means 18 Variable Reference voltage generation circuit 19 Fifth switch control circuit

Claims (4)

(57) [Claims] A rectifier circuit connected to a commercial AC power supply;
A first reference voltage generation circuit that generates a first reference voltage from an output of the rectifier circuit; and a first switch control that receives an output of the first reference voltage generation circuit and controls on / off of a first switch circuit. Circuit, a first current limiting circuit that limits the current flowing through the first switch circuit, a capacitor charged by the first switch circuit, and an output voltage detection circuit that detects an output voltage across the capacitor. And a power supply device including a second switch control circuit that receives the output of the output voltage detection circuit and controls the first switch control circuit. 2. A rectifier circuit connected to a commercial AC power supply,
A first reference voltage generation circuit that generates a first reference voltage from an output of the rectifier circuit; and a first switch control that receives an output of the first reference voltage generation circuit and controls on / off of a first switch circuit. Circuit, a first current limiting circuit that limits the current flowing through the first switch circuit, a capacitor charged by the first switch circuit, and an output voltage detection circuit that detects an output voltage across the capacitor. A second reference voltage generation circuit that generates a second reference voltage from the output of the rectifier circuit in preference to the first reference voltage generation circuit when the output voltage detection circuit operates; A power supply, comprising: a second switch circuit that switches between a circuit and a second reference voltage generation circuit; and a third switch control circuit that receives the output of the output voltage detection circuit and controls the second switch circuit. Location. 3. A rectifier circuit connected to a commercial AC power supply,
A first reference voltage generation circuit that generates a first reference voltage from an output of the rectifier circuit; and a first switch control that receives an output of the first reference voltage generation circuit and controls on / off of a first switch circuit. Circuit, a first current limiting circuit that limits the current flowing through the first switch circuit, a capacitor charged by the first switch circuit, and an output voltage detection circuit that detects an output voltage across the capacitor. A second current limiting circuit that limits the current flowing through the first switch circuit in preference to the first current limiting circuit when the output voltage detection circuit operates, a first current limiting circuit, and a second current limiting circuit. A power supply device comprising: a third switch circuit that switches a current limiting circuit; and a fourth switch control circuit that receives an output of the output voltage detection circuit and controls the third switch circuit. A rectifier circuit connected to a commercial AC power supply;
A first reference voltage generation circuit that generates a first reference voltage from an output of the rectifier circuit; and a first switch control that receives an output of the first reference voltage generation circuit and controls on / off of a first switch circuit. Circuit, a first current limiting circuit that limits the current flowing through the first switch circuit, a capacitor charged by the first switch circuit, and an output voltage detection circuit that detects an output voltage across the capacitor. A variable reference voltage generation circuit that receives an output of the output voltage detection circuit and generates a variable reference voltage corresponding to the output of the first switch circuit; A power supply device comprising a fifth switch control circuit that controls the first switch circuit prior to the fifth switch control circuit.