JPH04271277A - Power supply - Google Patents

Abstract

PURPOSE:To provide a power supply which can convert AC power supply voltage into a DC voltage through a simple circuitry. CONSTITUTION:The power supply comprises a rectifier circuit 2 connected with a commercial power supply 1, a current limiter circuit 3, a switch circuit 4 and a capacitor p connected in series with the output terminal of the rectifier circuit 2, and a switch control circuit 6 for controlling the switch circuit 4 wherein the capacitor 5 is charged with a current, limited by the current limiter circuit 3, when the voltage of the commercial power supply 1 is lower than a predetermined level.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to power supply circuits for electronic circuits in which the electronic circuits of equipment are used without being isolated from the commercial power source.

0002

2. Description of the Related Art In recent years, it has become common for household electrical appliances to be equipped with electronic circuits including active elements. Most wireless-related electronic circuits constitute secondary circuits that are insulated from the commercial power source, but there are also many home appliances that have electronic circuits that are not insulated from the commercial power source. When an electronic circuit is installed in a device, the configuration generally includes an electronic circuit and a power supply circuit that supplies power to the electronic circuit. For convenience of explanation, the commercial power supply will be referred to as a primary circuit below.

An example of the above-mentioned conventional primary circuit power supply will be described below with reference to FIGS. 3 and 4. In FIG. 3, 1 is a commercial power supply, 12 is an autotransformer, 13 is a rectifier circuit, 14 is a capacitor, and 15 is an electronic circuit serving as a load for the power supply.

The operation of the conventional power supply circuit configured as described above will be explained. The AC voltage of the commercial power source 1 is voltage-dropped by an autotransformer 12 . The dropped AC voltage is rectified by a rectifier circuit 13, and then smoothed by a capacitor 14 and converted into a DC voltage. This DC voltage is determined by the terminal output voltage of the autotransformer 12.

Further, FIG. 4 shows an additional resistor 16, and the same parts as those in FIG. 3 are given the same reference numerals. Its operation is as follows. Commercial power supply 1 is resistor 16
The voltage is rectified by a rectifier circuit 13, smoothed by a capacitor 14, and converted into a DC voltage. In this case, this DC voltage is determined by the resistance value of resistor 16.

[0006]

[Problems to be Solved by the Invention] However, since the method shown in FIG. 3 uses a transformer, it uses a large amount of materials, is expensive, is difficult to reduce cost, is heavy, large, inefficient, and generates heat. There are many problems. Further, the method shown in FIG. 4 has problems such as low efficiency, large heat generation due to the resistance, and inability to extract a large current because the voltage is dropped by the resistance.

The present invention aims to solve the problems of the conventional methods, and provides a power supply circuit that can convert AC power to DC voltage with a simple configuration. The primary purpose of this is to In connection with this first object, a second object is to provide a power supply circuit that can obtain multiple outputs of DC voltage.

[0008]

[Means for Solving the Problems] A first means of the present invention to achieve the first object is to provide a rectifier circuit connected to a commercial power source and a current limiting circuit connected in series between its output terminals. and a switch circuit, a capacitor, and a switch control circuit for controlling the switch circuit, the power supply circuit charging the capacitor with the current limited by the current limiting circuit while the voltage of the commercial power source is below a certain voltage. It is something.

A second means of the present invention for achieving the second object is a rectifier circuit connected to a commercial power source, a first current limiting circuit connected in series between its output terminals, and a rectifier circuit connected to a commercial power source. a switch circuit and a first capacitor, a second current limiting circuit, a second switch circuit, and a second capacitor, which are also connected in series between the output terminals, and the first switch circuit and the second capacitor. It is equipped with a switch control circuit that simultaneously controls the switch circuits, and when the voltage of the commercial power supply rectified by the rectifier circuit is below a certain value, the first current limiting circuit and the second capacitor are connected to the first capacitor and the second capacitor. This is a power supply circuit that performs charging with the current limited by the current limiting circuit and obtains multiple outputs at the same time.

0010

[Operation] The first means of the present invention is that while the voltage of the commercial power supply after being rectified by the rectifier circuit is lower than the reference voltage generated by the reference voltage generation circuit included in the switch control circuit, the switch control circuit The circuit shorts the switch circuit, charges the capacitor with current limited by the current limiting circuit, and serves to supply current to the load of the power supply. Further, when the voltage of the commercial AC power supply after being rectified by the rectifier circuit exceeds the reference voltage, the switch control circuit opens the switch circuit and acts to stop the current supply to the capacitor. Therefore, current is supplied to the load during this time by using the accumulated charge in the capacitor.

In this case, the current limiting circuit has a very important function as described below. In other words, this method generates noise because the switching operation is synchronized with the power supply frequency, but by limiting the current with a current limiting circuit,
This makes it possible to realize a practically useful power supply circuit that complies with the noise regulations applied to electronic devices. If the current is not limited by a current limiting circuit, it is difficult to comply with noise standards. Furthermore, by limiting the current with a current limiting circuit, it is possible to keep the ratings of components low, such as the maximum current rating of the switch circuit and the maximum allowable ripple current rating of the capacitor, making it possible to make practical components and comply with noise standards. A rational circuit can be realized.

A second means of the present invention has a configuration in which a second switch circuit, a second current limiting circuit, and a second capacitor are added to the configuration of the first means of the present invention. The switch control circuit can form a DC power source between both ends of the first capacitor and both ends of the second capacitor by controlling the second switch circuit simultaneously with the first switch circuit. be.

[0013]

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. In the figure, 1 is a commercial power supply, 2 is a rectifier circuit connected in series to the next stage of the commercial power supply 1, 3 is a current limiting circuit connected in series to the next stage of the rectifier circuit 2, and 4 is a current limit circuit after rectification. A switch circuit provided in the current-carrying line to turn on and off the current, 5 is a switch circuit 4
A capacitor that stores the current that passes through it. Also 6
is a switch control circuit that controls on/off the switch circuit 4, which includes a reference voltage generation circuit 6a and a switch drive circuit 6b.
It consists of The reference voltage generation circuit 6a is the rectifier circuit 2.
A constant reference voltage is created from the AC power supply after it has been rectified. Further, the switch drive circuit 6b compares the reference voltage obtained by the reference voltage generation circuit 6a with the voltage of the commercial power supply after being rectified by the rectifier circuit 2, and compares the voltage of the commercial power supply after being rectified by the rectifier circuit 2. is lower than the reference voltage, it acts to short-circuit the switch circuit 4. Further, when the same voltage is higher than the reference voltage, it acts to open the switch circuit 4. 7 is an electronic circuit which is a load connected to the power supply circuit of this embodiment. The current limiting circuit 3 is composed of a resistor, a constant current circuit, or the like, and has the function of limiting the current flowing through the circuit to a certain value or less.

The operation of this embodiment will be explained below. A positive half wave of the commercial power supply 1 is rectified by a rectifier circuit 2 . The reference voltage generation circuit 6a generates a constant reference voltage using this rectified voltage. On the other hand, the switch drive circuit 6b compares the output voltage of the rectifier circuit 2, that is, the positive half-wave instantaneous voltage, with the reference voltage, and turns on the switch circuit 4 when the instantaneous voltage is lower than the reference voltage, and turns on the switch circuit 4 when the instantaneous voltage is higher than the reference voltage. Acts off.

Now, the operation of this circuit will be considered in accordance with the movement of the output voltage of the commercial power supply after being rectified by the rectifier circuit 2. Until the voltage gradually increases from 0 and reaches the reference voltage, the switch circuit 4 is short-circuited, and the capacitor 5 is charged with commercial power, and at the same time, power is supplied to the load. Here, the current values of the charging current and the current supplied to the load are limited by the current limiting circuit 3. When the same voltage exceeds the reference voltage, the switch drive circuit 6b opens the switch circuit 4, and charging of the capacitor 5 is stopped.
Power is supplied to the load by the discharge current from the capacitor 5. When the voltage further increases and passes the peak of the commercial voltage, and the voltage drops and becomes lower than the reference voltage again, the switch drive circuit 6b short-circuits the switch circuit 4 again, and the capacitor 5 is charged with commercial power. After that, the commercial power supply voltage reaches 0 volts. The power supply circuit of this embodiment repeats the above operation.

The current limiting circuit 3 has an important function in this embodiment. This is because it is a condition for complying with the power line noise stipulated in each country. If the current is not limited by the current limiting circuit 3, it is difficult to comply with this standard, and the circuit cannot be used for practical use. Further, the current limiting circuit 3 may be inserted anywhere between the position after rectification by the rectifying circuit 2 and the capacitor 5. Further, when the switch circuit 4 is open, the capacitor 5 is not charged, and the capacitor 5 is not charged to the load 7.
of charging charge is supplied. Note that the reference voltage does not need to be a constantly maintained DC voltage, and the
A reference voltage formed immediately before or almost simultaneously with the switch operation of the switch circuit 4 and the switch circuit 4 may also be used. For example, when the voltage of the commercial power supply becomes equal to or higher than the reference voltage, a constant voltage that is clamped to one of the terminals by the reference voltage may be used.

Next, an embodiment of the second means of the present invention will be explained based on FIG. In this embodiment, the following circuit is added to the power supply circuit of the embodiment of the first means of the present invention. 8 is a second current limiting circuit connected to the next stage of the rectifier circuit 2, and 9 is a second switch circuit, which is synchronized with the first switch circuit 4 by a reference voltage generation circuit 6a and a switch control circuit 6b. controlled. 10 is a second capacitor, and 11 is a second load.

The operation of this embodiment will be explained below. By the reference voltage generation circuit 6a and the switch drive circuit 6b,
The first switch circuit 4 and the second switch circuit 9 are controlled simultaneously. Thereafter, charging of the first capacitor 5 and the second capacitor 10 and power supply to the first load 7 and the second load 11 are carried out in the same manner as in the embodiment of the first means of the present invention. be exposed. In this case, the second current limiting circuit 8 limits the current to the second circuit, and by changing the current limiting value of the second current limiting circuit 8, the value of the second DC voltage can be arbitrarily selected. Can be done. That is, a second power source is configured that shares a part of the embodiment of the first means of the present invention.

[0019]

As described above, according to the first means of the present invention, a rectifier circuit connected to a commercial power source, a current limiting circuit, a switch circuit, and a capacitor connected in series between its output terminals, The power supply circuit is equipped with a switch control circuit that controls the switch circuit, and complies with noise standards by charging the capacitor with the current limited by the current limiting circuit while the voltage of the commercial power source is below a certain voltage. It is possible to construct a small, lightweight, and inexpensive power supply circuit that generates little heat.

According to the second means of the present invention, a rectifier circuit connected to a commercial power supply, a first current limiting circuit, a first switch circuit, and a first current limiting circuit connected in series between the output terminals of the rectifier circuit are connected to a commercial power source. , a second current limiting circuit, a second switch circuit, a second capacitor, and the first switch circuit and the second switch circuit, which are similarly connected in series between the output terminals. Equipped with a switch control circuit,
While the voltage of the commercial power supply rectified by the rectifier circuit is below a certain value, the first capacitor and the second capacitor are charged with the current limited by the first current limiting circuit and the second current limiting circuit. As a power supply circuit that can obtain a plurality of outputs simultaneously, it is possible to realize a power supply circuit that can obtain a plurality of outputs of DC voltage.

[Brief explanation of the drawing]

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 a power supply circuit according to the second means of the present invention.

[Figure 3] Block diagram showing an example of a conventional power supply circuit

[Figure 4
] Block diagram showing another example of a conventional power supply circuit

[Explanation of symbols]

1 Commercial power supply 2 Rectifier circuit 3 Current limit circuit 4 Switch circuit 5 Capacitor 6 Switch control circuit 6a　Reference voltage generation circuit 6b Switch drive circuit 8 Second current limiting circuit 9 Second switch circuit

Claims (2)

[Claims] 1. A rectifying circuit connected to a commercial power supply, a current limiting circuit, a switch circuit, and a capacitor connected in series between the output terminals of the rectifier circuit, and a switch control circuit for controlling the switch circuit, A power supply circuit that charges the capacitor with a current limited by the current limiting circuit while the voltage is below a certain voltage. [Claim 2] A rectifier circuit connected to a commercial power source, a first current limiting circuit, a first switch circuit, and a first capacitor connected in series between its output terminals; A second current limiting circuit, a second switch circuit, a second capacitor connected in series, and a switch control circuit that simultaneously controls the first switch circuit and the second switch circuit, and rectify the current by a rectifier circuit. While the voltage of the commercial power supply is below a certain value, the first capacitor and the second capacitor are charged with the current limited by the first current limiting circuit and the second current limiting circuit, and multiple A power supply circuit that obtains outputs.