JPS61185069A - Dc/dc converter - Google Patents

Abstract

PURPOSE:To reduce the size and to suppress to temperature rise of a DC/DC converter by inserting a saturable reactor to a driven output circuit of a transformer, and electromagnetically coupling the choke coil of a main output coil and the choke coil of a driven output coil. CONSTITUTION:When a switch element 2 is closed, a voltage of a DC power source 1 is transmitted by a transformer 4 to the secondary windings 14, 5. The induced voltage of the winding 5 is fed through a saturable reactor 6 to a DC voltage by a rectifier. This voltage is input to a controller 11, which flows a reset current in response to the output voltage to the reactor 6 to be stabilized. Choke coils 19, 20 are electromagnetically coupled with the coil 19 as the primary coil and the coil 20 as the secondary coil.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a DC-DC converter, and more particularly to an improvement of a DC-DC converter using a saturable reactor.

[Prior art] In multi-output DC-DC converters, a Remy type magnetic control method is used in which the output voltage is controlled on the secondary side by a saturable reactor except for the main output, which directly controls the switching element on the primary side via a control circuit. is widely used.

Figure 2 shows a two-output DC-
A schematic configuration diagram of a DC converter is shown. 6 in the figure, the output circuit is the main output circuit, and the DC voltage outputted through the rectifier circuit equipped with the choke coil 19 is stabilized by controlling the switching element 2 by directly feeding it back to the control circuit 18. output voltage is obtained. In addition, when the output ■ is not controlled in any way, the output voltage is affected by the load fluctuation of the output ■ (usually called cross regulation), so a Remy type magnetic control method is used to control it on the secondary side. There is.

[Problems to be Solved by the Invention] However, in the conventional method described above, the driving frequency of the DC-DC converter and the dimensions of the saturable reactor 6 are limited due to the temperature rise of the saturable reactor 6 used. There was a problem in terms of miniaturization of the DC-DC converter.

(IEEJ Magnetics Study Group Material MAG-84-
23) [Means for Solving the Problems] In order to solve the above problems, the present invention provides a primary winding of a transformer having two or more secondary windings at both ends of a DC power supply and a switch element. are connected in series, generate an output voltage from one of the secondary windings of the transformer through a rectifier circuit having a choke fill, and return the output voltage to the switch element through a control circuit for control. The output voltage is generated from a main output circuit that stabilizes the output voltage by a rectifier circuit having a choke coil from another secondary winding of the transformer via a saturable reactor, and a secondary output voltage is generated by the saturable reactor. In the DC-DC converter, the saturable reactor is connected to the switch element on the secondary winding side that constitutes the secondary output circuit of the transformer. It is inserted and connected to the side that has positive polarity during the on period, and is characterized in that the choke coil of the main output circuit is used as a primary coil and the choke coil of the sub-output circuit is used as a secondary coil and electromagnetically coupled. It is.

[Example] Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a circuit diagram showing an embodiment of the DC-DC converter according to the present invention. When the switch element 2 is on,
The voltage of the DC power supply 1 is applied to the secondary windings 14 and 5 by the transformer 4.
are transmitted to each. The induced voltage in the secondary winding wire 14 is applied to the diodes 15, 16 and the choke coil 19. A DC voltage is generated at the output through an output rectifier circuit consisting of a capacitor 17, and this output voltage is fed back to the switch element 2 through a control circuit 18, and the output voltage is stabilized by directly controlling the ON and OFF periods. We are trying to

On the other hand, the induced voltage in the secondary winding 5 passes through the saturable reactor 6 and is transferred to the rectifier circuit (diode 7.8, choke coil 20,
(consisting of a capacitor 10) generates a DC voltage. This voltage is input to the control circuit 11, and is stabilized by the control circuit passing a reset current corresponding to the output voltage to the saturable reactor 6.

Here, the present invention is characterized in that the two-winding choke coil 9 is constructed by electromagnetically coupling the choke coil 19 as a primary coil and the choke coil 20 as a secondary coil, and by this coupling, high frequency effective Since the resistance Re can be reduced, the output voltage fluctuation △I due to the load current fluctuation ΔIL due to cross regulation is reduced.
Re can be reduced.

That is, in the present invention, since the cross regulation can be considerably improved by the two-winding choke coil 9, the saturable reactor only needs to compensate for the deficiency.
The load is reduced, and as a result, the heat generated by the saturable reactor is significantly reduced.

With this circuit configuration, the output ■ is +5V 2~10A1
Output ■ +12■ 0~4A switching frequency 20
As a result of making a prototype of a 0kHz DC-DC converter, the temperature rise in the saturable reactor was able to be significantly reduced compared to the conventional method, as shown in Table 1.

Table 1 Here, the load conditions are +5V output 10A, +12
The V output is OA, and the cross-sectional area of the iron core of the saturable reactor is 0.075 cm2. The average magnetic path length is 5.34 Cm.

[Effects of the Invention] According to the present invention, there is an effect that the temperature rise of the saturable reactor can be reduced even when driven at high frequency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram of a Remy type magnetically controlled DC-DC converter. 2... Switch element, 4... Transformer, 5.14...
・Secondary winding, 6...Saturable reactor, 9...Two winding choke.

Claims (1)

[Claims] A primary winding and a switch element of a transformer having two or more secondary windings are connected in series to both ends of a DC power supply, and an output voltage is output from one secondary winding of the transformer through a rectifier circuit having a choke coil. a main output circuit that stabilizes the output voltage by generating and controlling the output voltage by returning the output voltage to the switch element via a control circuit; A DC-DC converter comprising a secondary output circuit that generates an output voltage from a rectifier circuit having a choke coil and performs stabilization control of the output voltage on the secondary side using the saturable reactor, the saturable reactor comprising: the secondary winding constituting the secondary output circuit of the transformer is inserted and connected to the side that has positive polarity while the switch element is on, and the choke coil of the main output circuit is used as the primary coil; A DC-DC converter characterized in that a choke coil of an output circuit is electromagnetically coupled as a secondary coil.