JPH0479767A - Dc power supply circuit - Google Patents

Abstract

PURPOSE:To obtain a DC voltage circuit which has excellent ratio frequency characteristics and is suitable for size reduction at a low cost by a method wherein two control windings of a commutation choking coil are connected in series in such a manner that voltages induced in the respective control windings by an AC current applied to a main winding cancel each other and, further, a current is applied to the control windings by applying the output voltage of a smoothing circuit. CONSTITUTION:If a control current Ic is made to flow through the control windings 7f and 7g of a commutation choking coil 7 along the direction of arrows when a current is made to flow through the main winding 7e along the direction of arrows and magnetic fields are induced in the core along the directions of arrows F and G as shown in the figure, magnetic fields are induced in the outer cores 7b and 7c along the directions of arrows J and K. When the control current Ic is small, the impedance of the commutation choking coil 7 is large and the current flowing through the main winding 7e is small and hence an output voltage V01 is small. On the other hand, as a permeability mu becomes smaller when the control current Ic becomes larger, the impedance of the commutation choking coil 7 becomes smaller and hence the current applied to the main winding 7e is large and the output voltage V01 is large.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a DC power supply circuit that converts an AC current from an AC power supply circuit such as a commercial power supply circuit into a DC voltage and outputs the DC voltage.

[Prior Art] Conventionally, the one shown in FIG. 4 has been known as a DC power supply circuit. This DC power supply circuit includes a transformer 101,
an AC power supply circuit 102 that flows an AC current through the primary winding 101a of the transformer 101; a first rectifier circuit 103 that rectifies the AC current induced in the secondary winding 101b of the transformer 101;
The first smoothing circuit 104 reduces the pulsating current of the output voltage from now on.

The AC power supply circuit 102 includes an AC current generation circuit 105 and a transistor 106. Said first rectifier circuit 1
03, a saturable iron core 107 and a diode 108 are sequentially connected in series to one end of the secondary winding 101b of the transformer 101, a diode 109 is connected to the other end of the secondary winding 101b of the transformer 101, and 2 diode 108,1
It is made by connecting the output terminal of 09. Said first smoothing circuit 1
04 consists of a choke 110 and a capacitor 111, and the choke 110 is connected immediately after the first rectifier circuit 103.

The connection point between the choke 1]0 and the capacitor]] is connected to the emitter of the transistor 112. The collector of this transistor 112 is connected via a diode 113 to the connection point between the saturable iron core 107 and the diode 108 . A Zener diode 114 is connected between the connection point between the secondary winding 101b of the transformer 101 and the diode 109 and the base of the transistor 112.

By causing a reset current from the first smoothing circuit 104 to flow through the transistor 112 by a current value determined by the Zener diode 114, the DC output voltage V is determined. We are trying to stabilize 1-.

Further, in the conventional DC power supply circuit, two of the transformers 101
A second rectifier circuit 15 that rectifies the alternating current induced in the secondary winding 101b and another secondary winding 101C, and a second smoothing branch 116 that reduces the pulsating current of the output voltage. For direct current, power voltage V. I also got 2.

The second rectifier circuit 115 includes two diodes 117,
Consists of 118. The second smoothing circuit 116 includes a choke 119 and a capacitor 120.

[Problem to be solved by the invention] However, in the conventional DC power supply circuit, the saturable iron core 1
07 has a problem in that it needs to be made of a relatively expensive material (for example, an amorphous alloy material such as nickel-iron) that has a good squareness ratio and low coercive force, as shown by the curve in FIG.

Furthermore, in the conventional DC power supply circuit, in order to reduce the size of the transistor 106, the on/off time of the transistor 106 can be shortened and the switching frequency can be increased, but when the switching frequency is increased, the saturable iron core 107 is Curve E
As shown in Figure 2, the squareness ratio decreases and the coercive force increases, so the DC output voltage V. There is a problem that the control accuracy of 1- deteriorates and power loss also increases.

Furthermore, in the conventional DC voltage circuit, the transformer 10
The secondary windings 101b and 101c of 1 are
Since it is necessary to ensure a sufficient safe distance from the next winding 101a, there is a problem that the transformer is not suitable for miniaturization.

The object of the present invention is to provide low cost, good high frequency characteristics,
Another object of the present invention is to provide a DC voltage circuit that is suitable for downsizing.

[Means for Solving the Problems] According to the present invention, there is provided a transformer, an AC power supply circuit for passing an alternating current through the primary winding of the transformer, a core consisting of a center core and two outer cores, and a core of the transformer. A rectifier having a main winding wound around the transformer and a control winding wound around two outer cores, the main winding being connected between the secondary winding of the transformer and the rectifying diode. The rectifier circuit includes a rectifier circuit having a choke for use in the rectifier, and a smoothing circuit for reducing ripples in the output voltage. There is obtained a DC power supply circuit characterized in that the DC power supply circuits are connected in series so that the voltages applied to the control windings cancel each other out, and the output voltage of the smoothing circuit is applied to the control winding to cause a current to flow.

Further, according to the present invention, there is provided a transformer, an AC power supply circuit for passing an AC current through the primary winding of the transformer, a core consisting of a core and two outer cores, and a main winding wound around the core. A first transformer having a rectifying choke connected between a main winding or a secondary winding of the transformer and a rectifying diode. a rectifier circuit, a first smoothing circuit for reducing ripples in the output voltage, and rectifying an alternating current induced in one of the control windings by an alternating current flowing in the main winding of the rectifying choke; and a second smoothing circuit that reduces ripples in the output voltage, and the first rectifier circuit has two control windings of a rectifying choke connected to a main winding. The direct current is connected in series so that the voltages induced by the alternating current flowing through the circuits cancel each other out, and the output voltage of the first smoothing circuit is applied to the control winding to cause the current to flow. A power supply circuit is obtained.

[Example] Next, embodiments of the present invention will be described in detail based on the drawings.

In FIG. 1, reference numeral 1 indicates an AC power supply circuit. This AC power supply circuit 1 consists of an AC current generation circuit 2 and a transistor 3. The alternating current generating circuit 2 may be constructed from a commercial power source.

A primary winding 4a of a transformer 4 is connected to the collector of the transistor 3. The alternating current from the alternating current generating circuit 2 is passed through the primary winding 4a of the transformer 4 by the switching action of the transistor 3.

A first rectifier circuit 5 is connected to the secondary winding 4b of the transformer 4, which rectifies the alternating current induced therein. A first smoothing circuit 6 is connected to the first rectifying circuit 5 to reduce ripples in the output voltage from the first rectifying circuit 5.

DC output voltage V from this first smoothing circuit 6. 1 is obtained.

The first rectifier circuit 5 includes a rectifier choke 7 and a rectifier diode 8 connected in series to one end of the secondary winding 4b of the transformer 4, and a rectifier diode 8 connected to the other end of the secondary winding 4b of the transformer 4. It has a rectifying diode 9 connected thereto. 2
The two rectifier diodes 8 and 9 are each connected to an output terminal.

The rectifying choke 7 has a central core 7a as shown in FIG.
A core 7d consisting of two outer cores 7b and 7c, a main winding 7e wound around the center core 7a, and two outer cores 7b,
Control windings 7f and 7g are respectively wound around the coil 7c. The main winding 7e is the secondary winding 4b of the transformer 4.
and the rectifying diode 8.

The output terminal of the smoothing circuit 6 is connected to the emitter of the transistor 1°. The collector of this transistor 10 is connected via a diode 11 to one end of the control winding 7f. A Zener diode 12 is connected between the connection point between the secondary winding 4a of the transformer 4 and the control winding 7g and the base of the transistor 10.

The two control windings 7f and 7g are connected in series so that the voltages induced by the alternating current flowing through the main winding 7e cancel each other out. One end of the control winding 7g is connected to a connection point between the secondary winding 4b of the transformer 4 and the rectifying diode 9. A predetermined control voltage determined by the Zener diode 12 is applied to the two control windings 7f and 7g, and a control current flows therethrough. Note that a variable resistor may be used instead of the Zener diode 12.

The smoothing circuit 6 includes a smoothing choke 13 and a smoothing capacitor 14 connected in series, and these are connected in parallel to the rectifying diode 9 so that the smoothing choke 13 is located immediately after the rectifying circuit 5. It is connected to the.

The control winding 7f of the rectifying choke 7 includes a main winding 7.
A second rectifier circuit 15 is connected to rectify the alternating current induced by the alternating current flowing through e. A second smoothing circuit 16 is connected to the second rectifying circuit 15 to reduce ripples in the output voltage from now on. The DC output voltage from this smoothing circuit 6 is ■. 2 is obtained.

The second rectifier circuit 15 includes two rectifier diodes 1
Consists of 7.18. The second smoothing circuit 16 includes one smoothing choke and a smoothing capacitor 20.

Next, the operation of the above embodiment will be explained.

As shown in FIG. 2, the main winding 7 of the rectifying choke 7
When a current flows in the direction of the arrow in e and a magnetic field is generated in the core in the directions of the arrows F and G, when the control current 1c is caused to flow in the direction of the arrow in the control windings 7f and 7g, these control currents 1c cause an external Magnetic fields are generated in the directions of arrows J and K in the cores 7b and 7c, respectively.

The relationship between the magnetic field strength H and the magnetic flux density B of the outer cores 7b and 7c in this state is shown by the curved line in FIG. As the control current 1c flowing through the control windings 7b and 7c increases, the relationship between H and B changes from the curved region a to the curved regions A, C, and D.

As is clear from the curve in FIG. 3, the control current Ic
As the value increases, the magnetic permeability μ (μmB/H) decreases over time. Therefore, when the control current Ic is small, the impedance of the rectifying choke 7 is large, so the current flowing through the main winding 7e is small, so the pressure voltage becomes ■. 1 is small, and as the control current 1c increases, the magnetic permeability μ decreases, so the impedance of the rectifying choke 7 decreases, so the current flowing through the main winding 7e increases, resulting in the output voltage V. 1 or larger.

When the control current 1c is made larger than the control current IC corresponding to the curved area d in FIG. 3, the outer core 7c around which the control winding 7g is wound is magnetically saturated, and the magnetic circuit is This is the distance that passes through the wound outer core 7b.

In this way, by changing the control current Ic flowing through the control winding 7f7g of the rectifying choke 7, the output voltage V can be adjusted. 1, and the rectifying choke 7 has an outer core 7b.
, 7c need only have the characteristics shown by the curves in FIG. 3, so they can be made of a ferrite core or the like that is inexpensive and has good frequency characteristics.

A DC voltage V is generated from the AC current induced in the control winding 7f of the rectifying choke 7. 2, it is possible to reduce the number of insulation treatments or the required windings of the transformer 4.

[Effects of the Invention] The DC power supply circuit of the present invention is inexpensive, has good high frequency characteristics, and is suitable for miniaturization.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of the DC power supply circuit of the present invention, and FIG. 2 is a perspective view showing a rectifying choke of the same embodiment.
Fig. 3 is a characteristic diagram for explaining the present invention in detail, Fig. 4 is an electric circuit diagram showing a conventional DC power supply circuit, and Fig. 5 is a characteristic diagram for explaining the characteristics of the saturable iron core in the conventional DC power supply circuit. FIG. DESCRIPTION OF SYMBOLS 1... AC power supply circuit, 4... Transformer, 5... First rectifier circuit, 6... First smoothing circuit, 7... Rectifying choke, 7d... Core, 7e...・Main winding, 7f, 7
g... Control winding, 15... Second rectifier circuit, 16
...Second smoothing circuit.

Claims (1)

[Claims] (1) A transformer, an AC power supply circuit that flows AC current through its primary winding, a core consisting of a core and two outer cores, a main winding wound around the core, and two outer cores. a rectifier circuit having a control winding wound around a core thereof, and a rectifier choke having a main winding connected between a secondary winding of the transformer and a rectifier diode, and an output voltage from the rectifier circuit; and a smoothing circuit for reducing pulsating current of the rectifying choke, the rectifying circuit having two control windings of the rectifying choke connected in series so that voltages induced by alternating current flowing through the main winding cancel each other out. , and a DC power supply circuit characterized in that a current is caused to flow by applying an output voltage of a smoothing circuit to a control winding. (2) A transformer, an AC power supply circuit that passes an AC current through its primary winding, a core consisting of a center core and two outer cores, a main winding wound around the center core, and two outer cores. a first rectifier circuit having control windings each wound around a core, and a rectifier choke having a main winding connected between a secondary winding of the transformer and a rectifier diode; a first smoothing circuit that reduces ripples in the output voltage of the rectifying choke; and a second rectifier that rectifies the alternating current induced in one of the control windings by the alternating current flowing in the main winding of the rectifying choke. circuit, and a second smoothing circuit that reduces ripples in the output voltage from now on, the first rectifier circuit comprising:
The two control windings of the rectifying choke are connected in series so that the voltages induced by the alternating current flowing through the main winding cancel each other out, and the output voltage of the first smoothing circuit is applied to the control winding. A DC power supply circuit characterized in that a current is caused to flow through the DC power supply circuit.