JPH08322245A - Dc-dc converter - Google Patents

Abstract

PURPOSE: To maintain the turning-on resistance value of a switching element used for a rectifying means at a low level by respectively conducting a third and second switching elements in accordance with the presence and absence of the electric current of a first switching element. CONSTITUTION: When a first switching element (S) 3 is periodically turned on and off, an electric current flows to the S3 and another electric current flows to the secondary side of a current transformer 10 which detects the electric current flowing to the S3. When the electric current flows to the secondary side of the transformer 10, the transistor (Tr) 11a of a driving means 11 is turned off and a third S6 and Tr 11g are turned on. When the S3 is turned off and no electric current flows to the S3, a Tr 11b is turned on and the S6 is turned off. When the S6 is turned off, a Tr 11d is turned off and another Tr 11f is turned on. As a result, a second S5 is turned on. Since the output of a winding 1e for driving power wound around a transformer 1 is rectified by means of diodes 12a and 12b and a driving voltage is obtained by rectifying the voltage by means of a choke coil 12c and smoothing capacitor 12d, a voltage which does not change with time is supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC / DC converter using a switching element as rectifying means.

[0002]

2. Description of the Related Art FIG. 24 and FIG.
FIG. 11 is a circuit diagram showing a conventional DC / DC converter disclosed in Japanese Patent Publication No. 25314. In FIG. 24, 1 is a transformer having a primary winding 1a, a secondary winding 1b, and a reset winding 1c, 2 is a DC power supply, and 3 is a DC power supply 2 connected in series with the primary of the transformer 1. It is a first switching element that is connected to the winding 1a and periodically turns on / off the DC power supply 2. In this case, a field effect transistor (hereinafter referred to as MOSFET) made of a metal oxide semiconductor is used as the first switching element 3. Reference numeral 4 is a diode for exciting energy feedback, which is connected between the DC power supply 2 and the reset winding 1c of the transformer 1.

Reference numeral 5 is a second switching element, 5a is its parasitic diode, 6 is a third switching element,
6a is the parasitic diode. The second switching element 5 and the third switching element 6 are also M here.
OSFET is used. The second switching element 5 and the third switching element 6 are connected in series with each other and are connected to the secondary winding 1b of the transformer 1. Reference numeral 7 is a smoothing filter formed by a choke coil 7a and a smoothing capacitor 7b, and a second switching element 5 is connected in parallel to the input side thereof. 8
Reference numerals a and 8b are output terminals derived from the output side of the smoothing filter 7.

Further, in FIG. 25, 1 is a primary winding 1
a, a secondary winding 1b, a reset winding 1c, and also a control winding 1d, which is a transformer different from that shown in FIG. It is an inverter connected to 1d. The second switching element 5 and the third switching element 6 shown in FIG. 24 obtain the drive signal from the voltage of the secondary winding 1b of the transformer 1, but the second switching element 5 and the third switching element 6 shown in FIG.
The switching element 5 uses a signal generated by inverting the voltage generated in the control winding 1d of the transformer 1 by the inverter 9, and the third switching element 6 uses the voltage generated in the control winding 1d as it is as a drive signal. I am trying. Note that the other portions are portions corresponding to those denoted by the same reference numerals in FIG.

Next, the operation will be described. First, in the DC / DC converter shown in FIG.
The first switching element 3 connected in series with the DC power supply 2 to the next winding 1a is periodically on / off driven. When the first switching element 3 is on, the 1 of the transformer 1
When a voltage is applied from the DC power supply 2 to the secondary winding 1a and turned off, the diode 4 operates and the voltage applied to the primary winding 1a is inverted and applied to the reset winding 1c. Therefore, the voltage generated in the secondary winding 1b of the transformer 1 is
When the switching element 3 is turned on, a positive voltage is generated, and when it is turned off, a negative voltage is generated.

On the other hand, on the secondary side of the transformer 1, when the first switching element 3 is turned on, a positive voltage is generated in the secondary winding 1b, so that the third switching element 6 is turned on. As a result, the third switching element 6 operates as a rectifier with less voltage drop than the Schottky diode, and the current flows from the output terminal 8b to the third switching element 6, the secondary winding 1b, the choke coil 7a, and the output terminal 8a. And flows to a load (not shown) connected to the output terminals 8a and 8b. Further, when the first switching element 3 is turned off, a negative voltage is generated in the secondary winding 1b, so that the second switching element 5 is turned on. This time,
The third switching element 6 is reverse-biased and thus turned off. Here, in such a step-down type forward converter, the parasitic diode 5 is used as the secondary side diode.
Although a Schottky diode having a smaller voltage drop than a, 6a or a normal junction type diode is often used, the second switching element 5 in the ON state is a rectifier having a smaller voltage drop than the Schottky diode. Operate. Thereby, the current is output to the output terminal 8b, the second
The load connected to the output terminals 8a and 8b is circulated through the switching element 5, the choke coil 7a, and the output terminal 8a.

As described above, the DC /
In the DC converter, a drive signal and a drive power source for the second switching element 5 and the third switching element 6 are obtained from the voltage of the secondary winding 1b of the transformer 1, and the second switching element 5 and the third switching element 5 are driven. The switching element 6 is operated as a rectifier instead of a diode to reduce the voltage drop, thereby reducing the loss. Therefore, the loss that can be reduced is obtained by multiplying the output current by the difference between the voltage drop of the second switching element 5 and the third switching element 6 and the voltage drop of the diode. It is a value obtained by subtracting the drive power of the element 6.

When the exciting energy of the transformer 1 is completely regenerated to the DC power source 2 through the diode 4 while the first switching element 3 is off, the secondary winding 1b of the DC / DC converter of FIG. The voltage becomes zero, and the gate drive voltage cannot be applied to the second switching element 5. Therefore, a current flows through the parasitic diode 5a having a larger voltage drop than that of the Schottky diode, and it becomes impossible to keep the loss low. To prevent this, FIG.
In the DC / DC converter shown in FIG. 1, even if the voltage of the secondary winding 1b becomes zero after the reset of the transformer 1 is completed, the inverter 9 for applying the gate drive voltage to the second switching element 5 is provided. ing. In this case,
The drive signal and drive power of the circuit are the control winding 1d of the transformer 1.
Is obtained from

[0009]

Since the conventional DC / DC converter using the switching element as the rectifying means is configured as described above, the driving power source is the transformer 1.
It is obtained from the secondary winding 1b or the control winding 1d, and the drive voltage rises as the voltage of the DC power supply 2 increases. Therefore, when the driving power of the second switching element 5 and the third switching element 6 increases and the voltage of the DC power supply 2 increases, the loss of the DC / DC converter cannot be reduced so much. On the contrary, since the drive voltage becomes lower as the voltage of the DC power supply 2 becomes lower, the on-resistance of the second switching element 5 and the third switching element 6 used as the rectifying means increases and the voltage drop occurs. However, there is a problem that the size of the DC / DC converter becomes large and the loss cannot be reduced so much.

The present invention has been made in order to solve the above-mentioned problems, and maintains a low on-resistance and supplies an optimum drive voltage even if the input voltage fluctuates greatly, thereby reducing the rectification circuit. D, which is designed so that the effect of loss can be fully exerted
The purpose is to obtain a C / DC converter.

[0011]

D according to the invention of claim 1
In the C / DC converter, a first switching element is connected in series to a DC power source and connected to the primary winding of the transformer, and one end of a second switching element connected in parallel to the input side of the smoothing filter is connected to the transformer. One end of the next winding, the other end is the third
The current detecting means for detecting the current flowing through the first switching element, and the current flowing through the DC / DC converter connected to the other end of the secondary winding of the transformer via the switching element A driving unit that operates so that the third switching element conducts during the detection period and a second switching element conducts during the period when no current flows is detected, and a transformer for the driving unit. The output of the drive power supply winding is rectified and a drive power supply for supplying a smoothed voltage is added.

Further, in the DC / DC converter according to the invention of claim 2, the first switching element is connected in series to the direct current power source to be connected to the primary winding of the transformer, and is connected in parallel to the input side of the smoothing filter. And a DC / DC converter in which one end of the second switching element is connected to one end of the secondary winding of the transformer and the other end is connected to the other end of the secondary winding of the transformer through the third switching element. Drive signal transmitting means for transmitting a drive signal of the first switching element, and the third switching element is conductive while the ON signal is being output in synchronization with the transmitted drive signal of the first switching element. Then, a driving unit that operates so that the second switching element conducts during the period when the OFF signal is output, and a voltage obtained by rectifying and smoothing the output of the winding for the driving power supply of the transformer by the driving unit. It is obtained by adding a driving power supply.

In the DC / DC converter according to the third aspect of the present invention, the first switching element is connected in series to the DC power source to connect to the primary winding of the transformer, and is connected in parallel to the input side of the smoothing filter. And a DC / DC converter in which one end of the second switching element is connected to one end of the secondary winding of the transformer and the other end is connected to the other end of the secondary winding of the transformer through the third switching element. The third switching element conducts while the voltage generated in the winding of the transformer has the same polarity as that generated when the first switching element conducts, and the second switching element conducts when the voltage has the opposite polarity or zero voltage. Drive means for operating so as to conduct, and
A drive power supply for rectifying and smoothing the output of the drive power supply winding of the transformer is added to the drive means.

According to a fourth aspect of the present invention, there is provided a DC / DC converter in which a rectangular wave generator having a direct current as a power source is positive
Apply a signal with negative and zero periods to the primary winding of the transformer, connect switching elements to taps other than the center tap of the secondary winding with the center tap of the transformer, and pass the output through a smoothing filter. In the DC / DC converter which is obtained as a DC output, the current detecting means for detecting the current flowing in the primary winding of the transformer, the current flowing when a positive voltage is applied to the primary winding of the transformer During the period when it is detected that the current is flowing, only one of the two switching elements becomes non-conductive, and it is detected that the current flowing when the negative voltage is applied is flowing. During the period, the driving means that operates so that only the other switching element becomes non-conductive, and the winding for the driving power supply of the transformer Rectifying the output, it is obtained by adding a driving power source for supplying the smoothed voltage.

The DC / DC according to the invention of claim 5
The DC converter is a rectangular wave generator configured by a push-pull converter using two switching elements.

The DC / DC according to the invention of claim 6
The DC converter is a rectangular wave generator configured by a full-bridge converter using four switching elements.

Further, DC / according to the invention of claim 7
The DC converter is a rectangular wave generator configured by a half bridge converter using two switching elements and two capacitors.

The DC / DC converter according to an eighth aspect of the present invention is a DC / DC converter in which a rectangular wave generator having a DC power source
Apply a signal with negative and zero periods to the primary winding of the transformer, connect switching elements to taps other than the center tap of the secondary winding with the center tap of the transformer, and pass the output through a smoothing filter. A drive signal transmitting means for transmitting a drive signal of the rectangular wave generator to a DC / DC converter which is obtained as a DC output, and a period in which it is a positive voltage in synchronization with the signal transmitted by the drive signal transmitting means. Driving means for operating so that only one of the two switching elements is non-conductive and only the other switching element is non-conductive during a period of a negative voltage, and a driving means for driving the transformer. A drive power supply for rectifying and smoothing the output of the power supply winding is added.

According to a ninth aspect of the present invention, there is provided a DC / DC converter in which a rectangular wave generator having a direct current as a power source is positive
Apply a signal with negative and zero periods to the primary winding of the transformer, connect switching elements to taps other than the center tap of the secondary winding with the center tap of the transformer, and pass the output through a smoothing filter. In the DC / DC converter that is obtained as a DC output, only one of the two switching elements is non-conducting during the period when the voltage generated in the transformer winding is in the positive direction, and the period during the negative direction is A driving means for operating only the other switching element to be non-conductive, and a driving power supply for rectifying the output of the driving power supply winding of the transformer and supplying a smoothed voltage are added to the driving means.

Further, DC / DC according to the invention of claim 10
The converter is a rectangular wave generator powered by direct current,
A signal with positive, negative and zero periods is applied to the primary winding of the transformer, and four switching elements in full bridge connection or two switching elements in mixed bridge connection are connected to the secondary winding of the transformer. DC / D with a bridge circuit composed of two diodes connected to obtain the output of this bridge circuit as a DC output through a smoothing filter.
It is detected that the C converter has a current detecting means for detecting a current flowing through the primary winding of the transformer, and that a current flowing when a positive voltage is applied to the primary winding of the transformer is flowing therethrough. During the period, it is detected that only the switching element on one side of the switching elements on two diagonal sides of the bridge circuit is conductive and the current flowing when the negative voltage is applied is flowing. During this period, driving means for operating so that only the switching element on the other side is conductive, and a driving power supply for rectifying the output of the winding for the driving power supply of the transformer and supplying a smoothed voltage are added to this driving means. It is a thing.

Further, the DC according to the invention described in claim 11
The / DC converter connects the connection points of the switching element and the diode of the bridge circuit by the mixed bridge to the secondary windings of the transformer, respectively, and makes the ground level of the driving means and the driving power source common to each other, thereby providing two switching elements. Is connected to the earth level.

Further, the DC / DC according to the invention of claim 12
The converter is a rectangular wave generator powered by direct current,
A signal with positive, negative, and zero periods is applied to the primary winding of the transformer, and full bridge connection is made to the secondary winding of the transformer.
Two switching elements or two with mixed bridge connection
Drive signal transmission means for transmitting a drive signal of a rectangular wave generator to a DC / DC converter in which a bridge circuit including one switching element and two diodes is connected and the output of the bridge circuit is obtained as a DC output through a smoothing filter. , In the period in which the voltage is in the positive direction in synchronization with the transmitted signal, only the switching element on one side of the switching elements on the two diagonal sides of the bridge circuit conducts and the negative direction A drive means for operating so that only the switching element on the other side conducts during a voltage period and a drive power supply for rectifying and smoothing the output of the transformer drive power supply winding are added to this drive means. It was done.

DC / DC according to the invention of claim 13
The converter is a rectangular wave generator powered by direct current,
A signal with positive, negative, and zero periods is applied to the primary winding of the transformer, and full bridge connection is made to the secondary winding of the transformer.
Two switching elements or two with mixed bridge connection
In a DC / DC converter in which one switching element and a bridge circuit consisting of two diodes are connected and the output of this bridge circuit is obtained as a DC output through a smoothing filter, the voltage generated in the transformer winding is in the positive direction. Driving means for operating so that only the switching element on one side of the switching elements on two diagonal sides of the bridge circuit is conductive and only the switching element on the other side is conductive during a negative direction, Further, a drive power supply for rectifying and smoothing the output of the drive power supply winding of the transformer is added to the drive means.

[0024]

According to the present invention, the driving means receives the supply of the constant voltage stabilized by rectifying and smoothing the output of the winding for the driving power source of the transformer from the driving power source, and the first means by the current detecting means. By making the third switching element conductive while the current is detected to flow through the switching element, and making the second switching element conductive while the current is detected not flowing. The ON resistance value of the switching element used in the rectifying means can be kept low at all times, and the driving power of the switching element can be reduced by preventing negative voltage from being applied to the switching element.

Further, the driving means in the invention of claim 2 receives the supply of the constant voltage stabilized by rectifying and smoothing the output of the driving power supply winding of the transformer from the driving power supply, and the driving signal transmission means. In synchronization with the transmitted drive signal of the first switching element, the third switching element is made conductive during the period when it is an ON signal, and the second switching element is made conductive during the period when it is an OFF signal. It is possible to keep the on-resistance value of the switching element used in the rectifying means low at all times, and further, to prevent the negative voltage from being applied to the switching element and to reduce the driving power thereof.

The drive means in the invention of claim 3 receives a supply of a constant voltage stabilized by rectifying and smoothing the output of the drive power source winding of the transformer from the drive power source, and the transformer winding receives the voltage. By making the third switching element conductive when the generated voltage has the same polarity as the voltage generated when the first switching element is conductive, and making the second switching element conductive when it has the opposite polarity or zero voltage, It is possible to keep the on-resistance value of the switching element used in the rectifying means low at all times, and further, to prevent the negative voltage from being applied to the switching element and to reduce the driving power thereof.

Further, the drive means in the invention of claim 4 is supplied with a constant voltage stabilized by rectifying and smoothing the output of the drive power supply winding of the transformer from the drive power supply, and the transformer by the current detecting means. During the period when it is detected that the positive direction current that flows when the positive direction voltage is applied to the primary winding of the Only one of the two switching elements connected to each is made non-conducting, and the other is applied during the period in which it is detected that the negative current flowing when the negative voltage is applied is flowing. It is possible to keep the on resistance value of the switching element used for the rectifying means low at all times by turning off only the switching element of The switching element so as not to apply negative voltage to the driving power and small.

According to the fifth aspect of the present invention, in the rectangular wave generator, the two switching elements formed in the push-pull converter generate a rectangular wave signal having positive, negative, and zero periods using direct current as a power source. And apply it to the primary winding of the transformer.

Further, in the rectangular wave generator according to the invention described in claim 6, a rectangular wave signal having positive, negative and zero periods is generated by using a direct current as a power source, by four switching elements configured in a full bridge converter. And apply it to the primary winding of the transformer.

The rectangular wave generator according to the invention of claim 7 is a half-bridge converter.
With one switching element and two capacitors, positive,
A rectangular wave signal having a period of negative and zero is generated by using direct current as a power source and applied to the primary winding of the transformer.

The drive means in the invention of claim 8 receives the supply of a constant voltage stabilized by rectifying and smoothing the output of the drive power source winding of the transformer from the drive power source, and the drive signal transmitting means. In synchronization with the transmitted drive signal of the rectangular wave generator, during the period in which it is in the positive direction, two switchings are connected to each tap other than the center tap of the secondary winding with the center tap of the transformer. Always keep the on-resistance value of the switching element used for the rectifying means low by turning off only one of the switching elements and turning off the other switching element only in the negative direction. In addition, the driving power is made small by preventing the negative voltage from being applied to the switching element.

The drive means in the invention of claim 9 receives a supply of a constant voltage stabilized by rectifying and smoothing the output of the drive power supply winding of the transformer from the drive power supply, and the transformer winding receives During the period when the generated voltage is in the positive direction, only one of the two switching elements connected to each tap other than the center tap of the secondary winding with the center tap of the transformer is made non-conductive, By making only the other switching element non-conductive during the period in the negative direction, it is possible to keep the on-resistance value of the switching element used for the rectifying means low at all times, and the negative voltage is not applied to the switching element. Thus, the driving power is made small.

According to the tenth aspect of the present invention, the drive means receives a supply of a constant voltage stabilized by rectifying and smoothing the output of the drive power source winding of the transformer from the drive power source, and the transformer by the current detecting means. During the period in which it is detected that a positive current flows when a positive voltage is applied to the primary winding of the transformer, four full bridge connections are connected to the secondary winding of the transformer. A bridge circuit consisting of two switching elements and two diodes with a switching element or a mixed bridge connection,
During a period in which only the switching element on one side of the two pairs of diagonal sides is made conductive and a negative current flowing when a negative voltage is applied is detected. By making only the switching element on the other side conductive, it is possible to keep the on-resistance value of the switching element used for the rectifying means low at all times, and to drive the switching element without applying a negative voltage. Use small power.

According to the eleventh aspect of the present invention, in a bridge circuit, two switching elements each connected in series to a secondary winding of a transformer and two diodes are connected in parallel to each other. Connection point and 2
It is formed by a mixing bridge in which the input side of the smoothing filter is connected to the connection point of two diodes, and the connection point of the two switching elements is connected to the common drive means and the ground level of the drive power supply. Therefore, the number of driving power supplies is only one.

According to the twelfth aspect of the present invention, the drive means receives the supply of a constant voltage stabilized by rectifying and smoothing the output of the drive power source winding of the transformer from the drive power source, and the drive signal transmitting means. In synchronization with the transmitted drive signal of the rectangular wave generator, during the period in which it is in the positive direction, four switching elements in a full bridge connection or two in a mixed bridge connection are connected to the secondary winding of the transformer. In the bridge circuit consisting of the switching element and the two diodes, only the switching element on one side of the two pairs of diagonal sides is conductive, and only the switching element on the other side is conductive during the negative direction. By doing so, it is possible to keep the on resistance value of the switching element used for the rectifying means low at all times, and The ring element so as not to apply negative voltage to the driving power and small.

According to the thirteenth aspect of the present invention, the drive means receives a supply of a constant voltage stabilized by rectifying and smoothing the output of the drive power source winding of the transformer from the drive power source, and the transformer winding receives the voltage. During the period in which the generated voltage is in the positive direction, a pair of four switching elements with full bridge connection or two switching elements with mixed bridge connection and a bridge circuit with two diodes connected to the secondary winding of the transformer is paired. The switching element used for the rectifying means is turned on by making only the switching element on one side of the two pairs of angled sides conductive and making only the switching element on the other side conductive during the negative direction. It is possible to keep the resistance value low at all times, and to prevent negative voltage from being applied to the switching element. To the driving power and small ones Te.

[0037]

【Example】

Example 1. An embodiment of the present invention will be described below with reference to the drawings. 1 is a circuit diagram showing a DC / DC converter according to a first embodiment of the present invention. In the figure, 1 is a transformer, 1a is its primary winding, 1b is a secondary winding, 1c is a reset winding, 2 is a DC power supply, 3 is a first switching element, 4 is a diode, and 5 is a second. Switching element, 5
a is its parasitic diode, 6 is the third switching element, 6a is its parasitic diode, 7 is a smoothing filter, 7
a is the choke coil, 7b is a smoothing capacitor, 8a
Output terminals 8b and 8b are the same as or equivalent to those of the related art denoted by the same reference numerals in FIG. 24, and therefore detailed description thereof will be omitted. The duty of the drive pulse of the first switching element 3 is controlled so that the output voltage of the DC / DC converter is kept constant, and 37 is the output terminal 8a of the DC / DC converter.
In order to match the output voltage between 8b and the predetermined set value,
It is a pulse width controller for controlling the pulse width for turning on the first switching element 3. This is the same in other embodiments described below, though not shown.

Reference numeral 10 is a current transformer as an example of a current detecting means for detecting a current flowing through the first switching element 3, and 11 is a rectifying means for receiving a signal from the current transformer 10. It is a driving means for driving the second switching element 5 and the third switching element 6 that are present. The driving means 11 includes a transistor 11a,
The circuit formed by 11b and the gate resistor 11c drives the third switching element 6, and the transistor 11d and the resistor 11
e, the transistors 11f and 11g, and the gate resistor 1
The second switching element 5 is driven by the circuit formed by 1h. Reference numeral 12 denotes a drive power supply which supplies a stable and constant voltage to the drive means 11 irrespective of the voltage fluctuation of the DC power supply 2, and a drive power supply winding 1e wound around the transformer 1.
Diode 1 for rectifying the output of this drive power supply winding 1e
2a, 12b, and a choke coil 12c and a smoothing capacitor 12d for smoothing the rectified output thereof.

FIG. 2 is a waveform diagram for explaining the operation of the DC / DC converter according to the first embodiment shown in FIG. 1A shows the gate-source voltage V _GS1 of the first switching element 3, and FIG. 1B shows the current I _D1 flowing through the first switching element 3 detected by the current transformer 10. Waveform, FIG. 7C is a waveform of the gate-source voltage V _GS2 of the second switching element 5, FIG.
Is a waveform of the gate-source voltage V _GS3 of the third switching element 6.

Next, the operation will be described. Here, when the first switching element 3 is periodically turned on / off in accordance with the waveform of the voltage shown in FIG. 2A as in the conventional DC / DC converter, the on period from time t ₁ to time t ₂ 2B, a current starts flowing through the first switching element 3 as shown in FIG.
Current flows to the secondary side of the transistor 11a and the transistor 11a of the driving means 11 is turned on. When the transistor 11a is turned on, as shown in FIG. 2 (d), the third switching element 6
Is biased in the positive direction and the third switching element 6 is turned on. On the other hand, at this time, the driving means 11
Then, since the transistor 11d is also turned on, the transistor 11g is turned on, and the gate-source voltage of the second switching element 5 becomes zero as shown in FIG. 2 (c). Therefore, the second switching element 5 is turned off.

The first switching element 3 is turned on at time t.
_When it is turned off at ₂ , no current flows in the first switching element 3 and no current flows in the secondary side of the current transformer 10. Therefore, in the driving means 11, the transistor 11b is turned on, and the gate-source voltage of the third switching element 6 becomes zero as shown in FIG. 2 (d). As a result, the third switching element 6 is turned off. On the other hand, in the driving means 11, the transistor 11d is turned off at this time, so the transistor 11f is turned on. Therefore, as shown in FIG. 2C, the second switching element 5
Is biased in the positive direction, and the second switching element 5 is turned on.

Here, the drive voltage of the second switching element 5 and the third switching element 6 is supplied from the drive power supply 12, but unlike the conventional case shown in FIGS. 24 and 25, it is wound around the transformer 1. The output of the winding 1e for driving power supply is rectified by the diodes 12a and 12b, and the rectified voltage is smoothed by the choke coil 12c and the smoothing capacitor 12d to obtain the driving voltage. Supplied. Therefore, like the conventional DC / DC converter shown in FIGS. 24 and 25, the gate drive voltage to the second switching element 5 disappears while the first switching element 3 is off. There is no. Also,
Since a voltage waveform similar to that of the secondary winding 1b is generated in the drive power supply winding 1e of the transformer 1, pulse width control for making the output voltage constant by the pulse width controller 37 is performed by the drive power supply winding 1e. The same applies to the line 1e, and even if the voltage of the DC power supply 2 changes, the output voltage of the drive power supply 12 is always kept constant. Therefore, the gate of the second switching element 5
The source-to-source voltage V _GS2 and the gate-to-source voltage V _GS3 of the third switching element 6 can always give a constant and optimum voltage. In addition, even if the load current of this DC / DC converter changes,
The output voltage of the drive power supply 12 is kept constant because the voltage waveform hardly changes, only the current flowing through the secondary winding 1a and the secondary winding 1b changes. The ON resistance values of the second switching element 5 and the third switching element 6 depend on the voltage between the gate and the source thereof, so that a constant optimum voltage is always applied to reduce the voltage drop. Since it can be maintained and can be suppressed to a constant minimum required drive power regardless of fluctuations in the input voltage, a low-loss rectifier circuit can be configured. Further, in the conventional DC / DC converter, since the drive voltage is obtained from the winding of the transformer 1, a voltage in both positive and negative directions is applied between the gate and source of the second switching element 5 and the third switching element 6. However, in this embodiment, since a negative voltage is not applied, it is possible to realize a DC / DC converter having a very low drive power and a low loss rectifier circuit.

The first to third switching elements 3,
If the drain-source capacitance of 5 and 6 is large,
Since the transformer 1 can be reset by the LC resonance phenomenon, the reset winding 1c and the diode 4 can be omitted.

Example 2. Although the third switching element 6 is connected to the lower output terminal 8b side in the first embodiment, it may be connected to the upper output terminal 8a side as in the first embodiment. Produce the effect of.

FIG. 3 shows a DC / D according to the second embodiment of the present invention.
It is a circuit diagram which shows a C converter. In this embodiment, since the third switching element 6 is connected to the upper output terminal 8a side, the third switching element 6 is driven by the driving means 11A and the second switching element 5 is connected as shown in the figure. It is necessary to drive them separately by the drive means 11B. The driving means 11A and 11B are the same as the driving means 11 of the first embodiment.
The drive means 11A is a transistor 11
a, 11b and a gate resistor 11c, and the driving means 11B is composed of a transistor 11d and a resistor 11e, and transistors 11f and 11g and a gate resistor 11h. Note that 12A and 12B are drive power supplies that individually supply a stabilized constant voltage to each of these drive means 11A or 11B, and are wound around the transformer 1 like the drive power supply 12 in the first embodiment. Drive power supply winding 1e and diode 12
a, 12b, the choke coil 12c, and the smoothing capacitor 12d, or the drive power supply winding 1f,
It is composed of diodes 12e and 12f, a choke coil 12g, and a smoothing capacitor 12h.

Further, the current transformer 10 as the current detecting means.
Has a winding for obtaining the detection signal A sent to the driving means 11A and a winding for obtaining the detection signal B sent to the driving means 11B, respectively.
1 is different from that of the first embodiment shown in FIG. Note that the other parts are the same parts as those denoted by the same reference numerals in FIG. 1, and therefore description thereof will be omitted.

Here, the DC / DC converter according to the second embodiment basically operates in the same manner as the DC / DC converter according to the first embodiment, and the description thereof will be omitted.

Example 3. FIG. 4 is a circuit diagram showing a DC / DC converter according to a third embodiment of the present invention. Corresponding parts are designated by the same reference numerals as those in FIG. 1 and their explanations are omitted. In the figure, 13 is a control circuit for generating a signal for controlling the first switching element 3, and 14 is a signal from the control circuit 13 and outputs a drive signal C for driving the first switching element 3. It is a driving means. Reference numeral 15 is a drive signal transmission means for transmitting the drive signal C of the first switching element 3, which is a pulse transformer 15a having a primary winding, a secondary winding and a reset winding, and a pulse transformer 15a.
Of the switching element 15b connected to the primary winding, a resistor 15c connected in parallel to the secondary winding, and a diode 15d connected to the reset winding. 16
Is an auxiliary power supply for supplying power to the drive signal transmission means 15, and is composed of a drive power supply winding 1g wound around the transformer 1, diodes 16a and 16b, a choke coil 16c, and a smoothing capacitor 16d.

FIG. 5 is a waveform diagram for explaining the operation of the DC / DC converter according to the third embodiment shown in FIG. Incidentally, FIG. (A) shows the voltage waveform of the driving signal C supplied to the first switching element 3 from the driving circuit 14, Fig. (B) is a waveform of the voltage V _T generated in the resistor 15c of the drive signal transmitting means 15 FIG. 7C shows the waveform of the gate-source voltage V _GS2 of the second switching element 5, and FIG. 7D shows the waveform of the gate-source voltage V _GS3 of the third switching element 6. .

Next, the operation will be described. When the drive signal C shown in FIG. 5A is applied to the first switching element 3, the switching of the drive signal transmission means 15 is performed together with the first switching element 3 during the ON period from time t ₁ to time t _2. The element 15b is also turned on at the same time. Therefore, a voltage V _T in the positive direction is induced across the resistor 15c connected to the secondary winding of the pulse transformer 15a as shown in FIG. In the driving means 11, the transistor 1 is driven by this positive voltage V _T.
1a is turned on, and the gate of the third switching element 6 is biased in the positive direction as shown in FIG. As a result, the third switching element 6 is turned on.
On the other hand, since the transistor 11d is also turned on at this time, the transistor 11g is turned on, and the gate-source voltage of the second switching element 5 becomes zero as shown in FIG. 5 (c). As a result, the second switching element 5
Turns off.

The first switching element 3 is turned on at time t.
_When it is turned off at ₂ , the switching element 15b of the drive signal transmission means 15 is also turned off at the same time, and the pulse transformer 15
A voltage V _{T in the} negative direction as shown in FIG. 5B is generated and transmitted to the driving means 11 across the resistor 15c of the secondary winding a. In the driving means 11 which has received it, the transistor 11b is turned on, and the gate-source voltage of the third switching element 6 becomes zero as shown in FIG. 5 (d). As a result, the third switching element 6 is turned off. On the other hand, in the driving means 11, the transistor 11d is turned off at this time, so the transistor 11f is turned on. Therefore, as shown in FIG. 5C, the gate of the second switching element 5 is biased in the positive direction, and the second switching element 5 is turned on.

Also in the third embodiment, as in the case of the first embodiment, the drive voltage of the second switching element 5 and the third switching element 6 is given from the drive power supply 12, and the voltage fluctuation of the DC power supply 1 is generated. Since a stable and constant voltage can be always supplied regardless of the input voltage, the gate-source voltage V _{GS2 of} the second switching element 5 and the third switching element 6 The gate-source voltage V _GS3 is always given a constant optimum voltage, and it is possible not to apply a negative voltage. As a result, a low voltage drop can be maintained, and a constant and minimum required drive power can be suppressed regardless of fluctuations in the input voltage, so that a low loss rectifier circuit can be configured.

The third switching element 6 connected to the lower output terminal 8b side may be connected to the upper output terminal 8a side similarly to the second embodiment, and the first switching element 6 may be connected to the upper output terminal 8a side.
When the capacitance between the drain and the source of the third switching elements 3, 5, 6 is large, the transformer 1 can be reset by the LC resonance phenomenon, so that the reset winding 1c and the diode 4 can be omitted.

Example 4. 6 is a circuit diagram showing a DC / DC converter according to a fourth embodiment of the present invention. Corresponding parts are designated by the same reference numerals as those in FIG. 1 or FIG. In the figure, 17 is a resistor connected in parallel to a control winding (winding) 1d wound around the transformer 1, and the driving means 11 is connected to the voltage across the resistor 17, that is, the control winding 1d of the transformer 1. The second switching element 5 and the third switching element 6 are alternately driven according to the polarity of the generated voltage V _T.

Next, the operation will be described. When the first switching element 3 is periodically turned on / off, time t
₁ to the first switching element 3 at time t ₂ is the period of the on, the positive direction of voltage V _T as shown in FIG. 5 (b) are induced in the control winding 1d of the transformer 1, and the When the switching element 3 of No. 1 is turned off at time t ₂ , the control winding 1d
In this state, a negative voltage V _T is induced as shown in FIG. Thereafter, the same operation as in the case of the third embodiment is performed, and when the polarity of the voltage V _T is in the positive direction, the third switching element 6 becomes conductive, and in the case of the negative direction or zero voltage, the second switching element 6 is turned on. The switching elements 5 are alternately operated so as to be conductive.

Also in the fourth embodiment, as in the case of the first and third embodiments, the drive voltage of the second switching element 5 and the third switching element 6 is from the drive power source 12 to the DC power source 1. A stable and constant voltage is always applied regardless of voltage fluctuation, so a low voltage drop is maintained,
In addition, it is possible to suppress the required minimum drive power regardless of the fluctuation of the input voltage, and it is possible to prevent the voltage in the negative direction from being applied. Therefore, the drive power of the switching element can be further reduced. A low-loss rectifier circuit can be configured.

The third switching element 6 connected to the lower output terminal 8b may be connected to the upper output terminal 8a as in the second embodiment, or
Drains of the first to third switching elements 3, 5, 6
When the capacitance between the sources is large, the transformer 1 can be reset by the LC resonance phenomenon, so that the reset winding 1c and the diode 4 can be omitted.

Example 5. 7 is a circuit diagram showing a DC / DC converter according to a fifth embodiment of the present invention. Corresponding parts are designated by the same reference numerals as those in FIG. 1 and their description is omitted. In the figure, 18 is a transformer having center taps in the primary winding and the secondary winding, 18a ₁ and 18a ₂ are primary windings, 18b is the center tap, and 18c ₁ and 18c ₂
Is a tap other than the center tap 18b, 18d ₁ ,
18d ₂ is a secondary winding, 18e is its center tap, 1
Reference numerals 8f ₁ and 18f ₂ are taps other than the center tap 18e, and 18g and 18h are drive power source windings. In addition,
As the secondary windings 18d ₂ and 18d ₁ with the center tap 18e of this transformer 18, two windings having the same number of turns are connected in series and the connecting portion is used as a center tap, and the other tap of each winding is connected. The secondary winding with a center tap may be used in the meaning including them in this specification. In addition, this means that the primary winding 18a
_The same applies to ₁ and 18a ₂ .

Reference numeral 19 is a rectangular wave generator for generating a rectangular wave signal having positive, negative and zero periods by using the DC power supply 2 as a power source, and tap 18c _{1 of the} primary winding 18a ₁ of the transformer 18.
And a switching element 19a for turning on / off the supply of the DC power supply 2 to the tap 18c ₂ of the primary winding 18a ₂
b, a push-pull converter format is used. Reference numeral 20a is a current transformer as a current detecting means for detecting the current flowing through the primary winding 18a ₁ of the transformer 18.
Reference numeral 20b is a current transformer as a current detecting means for detecting a current flowing through the primary winding 18a ₂ . 21 and 22 is a switching element used as the rectifying means is connected between a tap 18f ₁ of the secondary winding 18 d ₁ and the secondary winding 18 d ₂ of the tap 18f ₂ of which are connected in series with the transformer 18 to each other The connection point is connected to the choke coil 7a of the smoothing filter 7 to form a double-wave rectification circuit. Reference numeral 21a is a parasitic diode of the switching element 21, and 22a is a parasitic diode of the switching element 22.

Reference numeral 23 is a drive means for driving the switching element 21 used as the rectifying means, and 24 is a drive means for similarly driving the switching element 22, which are resistors 23a or 24a and transistors 23b or 24b, and, respectively. It is composed of transistors 23c, 23d or 24c, 24d and a gate resistor 23e or 24e. 25 and 26 are drive power supplies for supplying a stable and constant voltage to the drive means 23 or 24 regardless of the voltage fluctuation of the DC power supply 2, as in the case of the drive power supply 12 of the first embodiment. Drive power supply winding 18g or 18h wound around the transformer 18, diodes 25a, 25b or 26a, 26b, choke coil 25c or 26c, and smoothing capacitor 25d.
Or 26d.

FIG. 8 is a waveform diagram for explaining the operation of the DC / DC converter according to the fifth embodiment shown in FIG. It should be noted that FIG. 7A shows the waveform of the voltage V _T1 induced in the primary winding 18a ₁ of the transformer 18, and FIG. 7B shows the current transformer 20a detecting the current flowing through the primary winding 18a _1. The waveform of the signal A to be output, the waveform (c) of FIG. 6C is the waveform of the signal B output by detecting the current flowing through the primary winding 18a ₂ by the current transformer 20b, and the waveform (d) of FIG. The waveform of the voltage V _GS1 between the sources is shown in FIG. _7E , which is the waveform of the voltage V _GS2 between the gate and the source of the switching element 22.

Next, the operation will be described. When the switching elements 19a and 19b of the rectangular wave generator 19 are driven on / off periodically, respectively, the switching element 19
In the period from time t ₁ to time t ₂ when a is on,
As shown in (a), a positive voltage V _T1 is induced on the primary side of the transformer 18. At that time, this switching element 1
The current flowing through the primary winding 18a ₁ of the transformer 18 via 9a is detected by the current transformer 20a, and a signal A as shown in FIG. 8B is obtained from the current transformer 20a and sent to the driving means 24. To be In the driving means 24, the transistor 24b is turned on by this signal A, whereby the transistor 24b is turned on.
Since d is turned on, the gate-source voltage of the switching element 22 becomes zero as shown in FIG. As a result, the switching element 22 is turned off.

On the other hand, during this period, the switching element 19b of the rectangular wave generator 19 is turned off, and the primary winding 18a _{2 of the} transformer 18 is passed through this switching element 19b.
No current is flowing through. Therefore, the signal B output from the current transformer 20b which has detected it becomes zero as shown in FIG. 8 (c). This signal B is sent to the driving means 23 to turn off its transistor 23b. Transistor 23b
Is turned off, the transistor 23c is turned on, and FIG.
As shown in (d), the gate of the switching element 21 is biased in the positive direction. As a result, the switching element 21
Keeps on.

When the switching element 19a is turned off at the time t ₂ , the voltage V _T1 becomes zero as shown in FIG. 8A, and the primary winding 18a passes through the switching element 19a.
_The current no longer flows to ₁ , and the signal A output from the current transformer 20a becomes zero as shown in FIG. 8 (b). This signal A turns off the transistor 24b of the driving means 24, so that the transistor 24c turns on. Therefore, FIG.
As shown in (e), the gate of the switching element 22 is biased in the positive direction, whereby the switching element 2
2 is turned on. On the other hand, since the state of the switching element 19b does not change, the switching element 21 maintains the ON state as described above.

Further, during the period from time t ₃ to time t ₄ when the switching element 19b of the rectangular wave generator 19 is on,
As shown in FIG. 8A, a negative positive voltage V _T1 is induced on the primary side of the transformer 18. At that time, the current flowing through the primary winding 18a ₂ of the transformer 18 is detected by the current transformer 20b via the switching element 19b, and the current transformer 20b generates a signal B as shown in FIG. Sent to the means 23. In the driving means 23, the signal B turns on the transistor 23b, which turns on the transistor 23d, so that the gate-source voltage of the switching element 23 becomes zero as shown in FIG. 8D. As a result, the switching element 23 is turned off.

On the other hand, during this period, the switching element 19a of the rectangular wave generator 19 is turned off, and the primary winding 18a _{1 of the} transformer 18 is passed through this switching element 19a.
No current is flowing through. Therefore, the signal A output from the current transformer 20a which has detected it becomes zero as shown in FIG. 8 (b). This signal A is sent to the driving means 24 to turn off its transistor 24b. Transistor 24b
Is turned off, the transistor 24c is turned on, and FIG.
As shown in (e), the gate of the switching element 22 remains biased in the positive direction. As a result, the switching element 22 maintains the ON state.

When the switching element 19b is turned off at time t ₄ , the voltage V _T1 becomes zero as shown in FIG. 8 (a), and the primary winding 18a passes through the switching element 19b.
_The current no longer flows to ₂ , and the signal B output from the current transformer 20b becomes zero as shown in FIG. 8 (c). This signal B turns off the transistor 23b of the driving means 23, so that the transistor 23c is turned on. Therefore, FIG.
As shown in (d), the gate of the switching element 21 is biased in the positive direction, whereby the switching element 2
1 is turned on. On the other hand, since the state of the switching element 19a does not change, the switching element 22 maintains the ON state as described above.

Here, the drive voltage is applied to the switching element 21 from the drive power supply 25 and the drive voltage is applied to the switching element 22 from the drive power supply 26, respectively, as in the case of the drive power supply 12 in the first embodiment. DC power supply 2
Since a stable and constant voltage is always supplied regardless of the voltage fluctuations of the switching elements 21 and 22, the gate-source voltages V _GS1 and V _GS2 of the switching elements 21 and 22 are always A constant optimum voltage can be applied. As a result, a low voltage drop can be maintained, and a constant minimum required drive power can be suppressed regardless of fluctuations in the input voltage, and a negative voltage can be prevented from being applied. And a low loss rectifier circuit can be constructed.

Example 6. In the fifth embodiment, the push-pull converter is constituted by the switching elements 19a and 19b as the rectangular wave generator 19 which generates the rectangular wave signal having the positive, negative and zero periods by using the DC power supply 2 as the power supply. However, a full-bridge converter may be used and the same effect as that of the above-described embodiment can be obtained.

FIG. 9 shows a DC / D according to the sixth embodiment of the present invention.
It is a circuit diagram which shows a C converter. In the figure, 19c
.About.19f are switching elements, and these four switching elements 19c to 19f are bridge-connected to form a rectangular wave generator 19 having a full-bridge converter configuration. In this case, the transformer 18 is wound with the primary winding 18a having no center tap, and the current detecting means detects the direction of the current flowing through the primary winding 18a to detect the signal A and the signal B. One output current transformer 20 is used.

DC according to the sixth embodiment configured as described above
In the / DC converter, when the switching elements 19c and 19f of the rectangular wave generator 19 are turned on, the DC power supply 2 → the switching element 19c → the primary winding 18a of the transformer 18 →
In the path of current transformer 20 → switching element 19f → DC power source 2, and when switching elements 19d and 19e are turned on, DC power source 2 → switching element 19e → current transformer 2
A current flows through the path of 0 → the primary winding 18a of the transformer 18 → the switching element 19d → the DC power supply 2. Current transformer 20
Detects the direction of this current, generates a signal A or a signal B, and sends it to the driving means 23 or 24. The other operations are almost the same as those in the case of the fifth embodiment shown in FIG. 7, and the description thereof will be omitted.

Example 7. In the sixth embodiment, the DC power source 2 is used as a power source, and the rectangular wave generator 19 that generates a rectangular wave voltage having positive, negative, and zero periods is used as a full bridge converter including four switching elements 19c to 19f. Although the configuration is shown, the configuration may be a half-bridge converter having two switching elements and two capacitors, and the same effect as that of the above-described embodiment is obtained.

FIG. 10 shows a DC / DC converter according to a seventh embodiment of the present invention.
It is a circuit diagram showing a DC converter.
g and 19h are switching elements, and 19i and 19j are capacitors, which are bridge-connected to form a rectangular wave generator 19 having a half-bridge converter configuration. In this case as well, the transformer 18 is wound with the primary winding 18a having no center tap, and the current detecting means detects the direction of the current flowing through the primary winding 18a to detect the signal A and the signal B. One current transformer 20 that outputs is used.

DC according to the seventh embodiment configured as described above
In the / DC converter, when the switching element 19g of the rectangular wave generator 19 is turned on, the DC power supply 2 → the switching element 19g → the primary winding 18a of the transformer 18 → the current transformer 2
0 → capacitor 19j → DC power supply 2 and when switching element 19h is turned on, DC power supply 2 → capacitor 19i → current transformer 20 → primary winding 1 of transformer 18
A current flows through the path of 8a → switching element 19h → DC power supply 2. The current transformer 20 detects the direction of this current, generates a signal A or a signal B, and sends it to the driving means 23 or 24. The other operations are almost the same as those in the case of the fifth embodiment shown in FIG. 7, and the description thereof will be omitted.

Example 8. FIG. 11 is a circuit diagram showing a DC / DC converter according to an eighth embodiment of the present invention. Corresponding parts are designated by the same reference numerals as those in FIGS. 4 and 7 and their description is omitted. In the figure, 27 is a control circuit for generating a signal for controlling the switching elements 19a and 19b of the rectangular wave generator 19, and 28a is a drive signal C for receiving a signal from the control circuit 27 and driving the switching element 19a. And 28b is a drive circuit which outputs a drive signal D for driving the switching element 19b. Reference numeral 29 is a drive signal transmission means for receiving a power supply from the auxiliary power supply 16 and transmitting a drive signal C for driving the switching element 19a of the rectangular wave generator 19 and a drive signal D for driving the switching element 19b.
The drive signal transmitting means 29 is connected to a pulse transformer 29a having a primary winding having a center tap and two secondary windings, and a tap other than the center tap of the primary winding of the pulse transformer 29a. It is composed of two switching elements 29b and 29c and resistors 29d and 29e connected in parallel to each secondary winding.

FIG. 12 is a waveform diagram for explaining the operation of the DC / DC converter according to the eighth embodiment shown in FIG. It should be noted that FIG. 7A shows the waveform of the voltage V _T1 induced in the primary winding 18a ₁ of the transformer 18, and FIG. 7B shows the drive signal applied from the drive circuit 28a to the switching element 19a of the rectangular wave generator 19. The waveform of C, the waveform (c) of FIG. 6 is the waveform of the drive signal D that is similarly applied to the switching element 19b from the drive circuit 28b, and the waveform (d) of the same is the waveform of the signal A generated in the resistor 29d of the drive signal transmission means 29. The figure (e) also shows the waveform of the signal B generated in the resistor 29e, the figure (f) shows the waveform of the gate-source voltage V _GS1 of the switching element 21, and the figure (g) shows the switching element 22.
_Is a waveform of the voltage V _GS2 between the gate and the source of the.

Next, the operation will be described. The drive signal C from the drive circuit 28a is applied to the switching element 19a of the rectangular wave generator 19 as shown in FIG. 12 (b). The period from time t ₁ ~ time t ₂ when the switching element 19a is turned on, 12 a forward voltage as shown in (a) V _T1
Are induced on the primary side of the transformer 18. At this time, the switching element 29b of the drive signal transmission means 29 is also turned on by the drive signal C. Therefore, a positive voltage is induced at both ends of the resistor 29d connected to one secondary winding of the pulse transformer 29a in the drive signal transmitting means 29, as shown in FIG. A is transmitted to the driving means 24. The drive means 24 uses this signal A
This turns on the transistor 24b and turns on the transistor 24d. Therefore, as shown in FIG. 12G, the voltage between the gate and the source of the switching element 22 becomes zero, which turns off the switching element 22.

On the other hand, during this period, the voltage induced in the resistor 29e connected to the other secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 is as shown in FIG.
As shown in (e), it becomes a negative voltage, which is signal B.
Is transmitted to the driving means 23. In the driving means 23, the signal B turns off the transistor 23b and turns on the transistor 23c. Therefore, FIG.
As shown in (3), the gate of the switching element 21 is biased in the positive direction, whereby the switching element 21 maintains the ON state.

When the switching element 19a of the rectangular wave generator 19 is turned off at time t ₂ as shown in FIG. 12 (b), the voltage V _T1 becomes zero as shown in FIG. 12 (a), and at that time,
Also in the drive signal transmission means 29, the switching element 29b is turned off by the drive signal C. Therefore, the signal A output from the resistor 29d of one secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 is as shown in FIG.
It becomes zero like. In the driving means 24, the transistor 24b is turned off by the signal A, and the transistor 24b is turned off.
c is turned on. As a result, the gate of the switching element 22 is biased in the positive direction and turned on as shown in FIG. On the other hand, during this period, the signal B output from the resistor 29e of the other secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 is also shown in FIG.
Since it becomes zero as shown in (e), the switching element 21 maintains the ON state as in the period from the time t ₁ to the time t ₂ .

Further, the drive signal D from the drive circuit 28b is applied to the switching element 19b of the rectangular wave generator 19 as shown in FIG.
2 (c). Switching element 19b
The period between times t ₃ ~ time t ₄ but which is turned on, FIG. 12
A negative voltage V _T1 as shown in (a) is induced on the primary side of the transformer 18. At this time, the switching element 29c of the drive signal transmission means 29 is also turned on by the drive signal D. Therefore, the resistor 2 connected to one of the secondary windings of the pulse transformer 29a in the drive signal transmitting means 29.
A voltage in the positive direction is induced at both ends of 9e as shown in FIG. 12 (e), and this is transmitted to drive means 23 as signal B. In the driving means 23, the signal B turns on the transistor 23b and turns on the transistor 23d. Therefore, as shown in FIG. 12 (f), the gate-source voltage of the switching element 21 becomes zero, which turns off the switching element 21.

On the other hand, during this period, the voltage induced in the resistor 29d connected to the other secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 is as shown in FIG.
As shown in (d), it becomes a negative voltage, which is signal A.
Is transmitted to the driving means 24. In the driving means 24, the signal A turns off the transistor 24b and turns on the transistor 24c. Therefore, as shown in FIG. 12 (g), the gate of the switching element 22 is biased in the positive direction, whereby the switching element 22 maintains the ON state.

When the switching element 19b of the rectangular wave generator 19 is turned off at time t ₄ as shown in FIG. 12C, the voltage V _T1 becomes zero as shown in FIG. 12A, and at that time,
In the drive signal transmission means 29, the drive signal D also turns off the switching element 29c. Therefore, the signal B output from the resistor 29e connected to one of the secondary windings of the pulse transformer 29a in the drive signal transmitting means 29 becomes zero as shown in FIG. 12 (e). In the driving means 23, the signal B turns off the transistor 23b and turns on the transistor 23c. As a result, FIG.
As shown in, the gate of the switching element 21 is biased in the positive direction and turned on. On the other hand, during this period, the signal A output from the resistor 29d connected to the other side of the secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 is also zero as shown in FIG. 12 (d). since, similarly to the period of the time t ₃ ~ time t _4, the switching element 22 is kept on.

Here, the driving voltage is applied to the switching element 21 from the driving power supply 25 and the switching element 22 is applied from the driving power supply 26, respectively. Since the constant voltage which is always stabilized is supplied regardless of the voltage fluctuation of the DC power supply 2, the voltage V between the gate and the source of the switching elements 21 and 22 is changed even if the input voltage fluctuates.
_GS1 and V _GS2 can always give a constant and optimum voltage. As a result, a low voltage drop can be maintained, and the drive power can be suppressed to a constant minimum required power regardless of fluctuations in the input voltage.
Since it is possible to avoid applying a negative voltage,
Further, the driving power can be reduced and a low loss rectifier circuit can be configured.

In the eighth embodiment, the push-pull converter is used as the rectangular wave generator 19 for generating the rectangular wave voltage having the positive, negative and zero periods by using the DC power supply 2 as a power source. However, Example 6 and Example 7
Similarly, a half-bridge converter or a full-bridge converter may be used.

Example 9. FIG. 13 is a circuit diagram showing a DC / DC converter according to a ninth embodiment of the present invention. Each part is given the same reference numeral as the corresponding part in FIG. 7 and its description is omitted. In this case, the transformer 18 has a primary winding 1
8a ₁ , 18a ₂ , secondary windings 18d ₁ , 18d ₂ , drive power supply windings 18g, 18h, and control windings (windings)
Drive means 23 and 24 are provided with 18i and 18j, and control the switching elements 21 and 22 according to the polarities of the voltages generated in the control windings 18i and 18j.

FIG. 14 is a waveform diagram for explaining the operation of the DC / DC converter according to the ninth embodiment shown in FIG. 1A shows the waveform of the voltage V _T1 induced in the primary winding 18a ₁ of the transformer 18, and FIG. 6B shows the waveform of the voltage V _T2 induced in the control winding 18i of the transformer 18. (C) shows the waveform of the voltage V _T3 induced in the control winding 18j of the transformer 18, and (d) shows the switching element 2
Waveform of the voltage V _GS2 between the gate and source of Figure ₂ , (e)
Is the voltage V between the gate and source of the switching element 21.
_{This is} the waveform of _GS1 .

Next, the operation will be described. Switching elements 19a of the rectangular wave generator 19 and 19b of periodically turning on / off driving respectively, in a period of time t ₁ ~ time t ₂ when the switching element 19a is turned on, transformer 1
The voltage V in the positive direction as shown in FIG.
_T1 is induced. At that time, the control winding 18i is also shown in FIG.
A positive-direction voltage V _T2 as shown in (b) is induced and sent to the driving means 23. The driving means 23 that has received the voltage V _{T2 in the} positive direction makes the voltage V _GS1 between the gate and source of the switching element 21 positive as shown in FIG. Become. On the other hand, in the control winding 18j, a negative voltage V _T3 as shown in FIG. The driving means 24 which has received the negative voltage V _T3 sets the gate-source voltage V _GS2 of the switching element 22 to zero as shown in FIG. _14D , whereby the switching element 22 is turned off. .

[0088] Turning off the switching element 19a at time t _2, the with voltage V _T1 becomes zero as shown in FIG. 14 (a), the control winding voltage V _T2 and the control winding of the 18i 18
The voltage V _{T3 of} j also becomes zero as shown in FIGS. 14 (b) and 14 (c). Therefore, FIG. 14 (e) and FIG.
As shown in (d), the gates of the switching elements 21 and 22 are both positively biased by the driving means 23 and 24, the switching element 21 remains in the ON state, and the switching element 22 in the OFF state is turned on.

Further, during the period from the time t ₃ to the time t ₄ when the switching element 19b is ON, the negative voltage V _T1 as shown in FIG. 14A is induced on the primary side of the transformer 18. A negative voltage V _T2 as shown in FIG. 14B is also induced in the control winding 18i. This negative voltage V _T2
The drive means 23 receiving the control winding 18i from the control winding 18i outputs the gate-source voltage V _GS1 of the switching element 21 as shown in FIG.
Since it is zero as shown in (e), the switching element 2
1 is turned off. On the other hand, FIG.
A voltage V _{T3 in the} positive direction as shown in (c) is induced, and the driving means 24 that receives the voltage causes the switching element 22 to bias the gate-source voltage V _GS2 in the positive direction as shown in FIG. 14 (d). Therefore, the ON state is maintained.

When the switching element 19b is turned off at time t ₄ , the voltage V _T1 becomes zero as shown in FIG. 14A, and the voltage V _T2 of the control winding 18i and the control winding 18
V _{T3 of} j is also zero as shown in FIGS. 14 (b) and 14 (c). Therefore, FIG. 14 (e) and FIG. 14 (d)
As described above, the gates of the switching elements 21 and 22 are both positively biased by the driving means 23 and 24, the switching element 21 in the off state is turned on, and the switching element 22 in the off state remains in the on state. maintain.

Here, the driving voltage is applied to the switching element 21 from the driving power supply 25 and the switching element 22 is applied from the driving power supply 26, respectively. These are the same as in the case of the driving power supply 12 of the first embodiment. Since the constant voltage which is always stabilized is supplied regardless of the voltage fluctuation of the DC power supply 2, the voltage V between the gate and the source of the switching elements 21 and 22 is changed even if the input voltage fluctuates.
_GS1 and V _GS2 can always give a constant and optimum voltage. As a result, a low voltage drop can be maintained, and the drive power can be suppressed to a constant minimum required power regardless of fluctuations in the input voltage.
Since it is possible to avoid applying a negative voltage,
Further, the driving power can be reduced and a low loss rectifier circuit can be configured.

In the ninth embodiment, the push-pull converter is used as the rectangular wave generator 19 which uses the DC power supply 2 as a power supply and generates a rectangular wave signal having positive, negative and zero periods. However, as in the case of the sixth and seventh embodiments, a configuration such as a full bridge converter or a half bridge converter may be adopted.

Example 10. FIG. 15 is a first embodiment of the present invention.
FIG. 8 is a circuit diagram showing a DC / DC converter based on 0, corresponding portions are assigned the same reference numerals as in FIG. 7, and description thereof will be omitted. In the figure, reference numeral 30 designates a transformer, which is a primary winding 30a ₁ and 30a ₂ provided with a center tap and a secondary winding 30.
b, and the driving power supply windings 30c and 30d. Reference numeral 31 is a bridge circuit connected to the secondary winding 39b of the transformer 30, and is composed of two switching elements 31a and 31b and two diodes 31c and 31d that are mixed bridge connected. 31
e and 31f are parasitic diodes of the switching element 31a or 31b. Reference numeral 32 is a driving means for driving the switching element 31a of the bridge circuit 31, and 33 is also driving means for driving the switching element 31b, which are transistors 32a, 32b or 33, respectively.
a, 33b, and the gate resistor 32c or 33c.

FIG. 16 shows the DC / DC shown in FIG.
FIG. 6 is a waveform diagram for explaining the operation of the converter. It should be noted that FIG. 10A shows the waveform of the voltage V _T1 induced in the primary winding 30a ₁ of the transformer 30, and FIG.
The waveform of the signal A which detects and outputs the current of the secondary winding 30a ₁ , the figure (c) shows the waveform of the signal B which the current transformer 20b detects and outputs the current of the primary winding 30a ₂ , (D) shows the waveform of the gate-source voltage V _GS1 of the switching element 31 a of the bridge circuit 31, and (e) shows the waveform of the gate-source voltage V _GS2 of the switching element 31 b.

Next, the operation will be described. When the switching elements 19a and 19b of the rectangular wave generator 19 are driven on / off periodically, respectively, the switching element 19
In the period from time t ₁ to time t ₂ when a is on,
A positive voltage V _T1 as shown in (a) is induced on the primary side of the transformer 30. At that time, this switching element 1
Current flows through the primary winding 30a ₁ of the transformer 30 via 9a, and the current is detected from the current transformer 20a shown in FIG. 16 (b).
A signal A such as is sent to the driving means 32. Drive means 3
2, the transistor 32a is turned on by this signal A, so that the switching element 31a of the bridge circuit 31 is turned on.
Has its gate biased in the positive direction as shown in FIG. As a result, the switching element 31
a is turned on.

On the other hand, during this period, the switching element 19b of the rectangular wave generator 19 is off, and the primary winding 30a _{2 of the} transformer 30 is passed through this switching element 19b.
No current flows through Therefore, the signal B output from the current transformer 20b which has detected it becomes zero as shown in FIG. 16 (c). This signal B is sent to the driving means 33 to turn on the transistor 33b thereof, so that the gate-source voltage of the switching element 31b of the bridge circuit 31 becomes zero as shown in FIG. 16 (e). As a result, the switching element 31b maintains the off state. At that time, in the bridge circuit 31, the diode 31d diagonally connected to the switching element 31a in the ON state is turned on to rectify the output of the secondary winding 30b, and the switching element 31b in the OFF state.
The diode 31c that is diagonal to is non-conductive.

[0097] When at time t ₂ to turn off the switching element 19a, with the voltage V _T1 becomes zero as shown in FIG. 16 (a), 1 winding 30 via the switching element 19a
No current flows through a ₁ . Thereby the current transformer 20a
The output signal A becomes zero as shown in FIG. 16B, and the transistor 32b of the driving means 32 is turned on. Therefore, the gate-source voltage of the switching element 31a becomes zero as shown in FIG. 16 (d), which turns off the switching element 31a in the bridge circuit 31. On the other hand, since the state of the switching element 19b does not change, the switching element 31b maintains the off state as described above. In the period from time t ₂ to time t ₃ , the secondary winding 3 of the transformer 30 is driven by the diode 31d and the parasitic diode 31e of the switching element 31a.
Rectify the output of 0b.

Further, during the period from time t ₃ to time t ₄ when the switching element 19b of the rectangular wave generator 19 is on,
A negative voltage V _T1 as shown in FIG. 16A is induced on the primary side of the transformer 30. At that time, the current flowing through the primary winding 30a ₂ of the transformer 30 via the switching element 19b is detected by the current transformer 20b, and the current transformer 20b generates a signal B as shown in (c) of FIG. Sent to. Since the transistor 33a is turned on by the signal B in the driving means 33, the gate of the switching element 31b of the gate circuit 31 is biased in the positive direction as shown in FIG. As a result, this switching element 3
1b is turned on.

On the other hand, during this period, the switching element 19a of the rectangular wave generator 19 is turned off, and the primary winding 30a _{1 of the} transformer 30 is connected via this switching element 19a.
No current flows through Therefore, the signal A output from the current transformer 20a which has detected it becomes zero as shown in FIG. 16 (b). This signal A is sent to the driving means 32 to turn on its transistor 32b.
As shown in (d), the gate-source voltage of the switching element 31a is maintained at zero. As a result, the switching element 31a of the bridge circuit 31 maintains the off state. At that time, in the bridge circuit 31,
The diode 31c, which is diagonal to the switching element 31b in the ON state, becomes conductive, rectifies the output of the secondary winding 30b, and the switching element 3 in the OFF state.
The diode 31d diagonal to 1a is non-conductive.

When the switching element 19b is turned off at time t ₄ , the voltage V _T1 becomes zero as shown in FIG. 16 (a), and the primary winding 30 passes through the switching element 19b.
No current flows through a ₂ . Thereby the current transformer 20b
The output signal B becomes zero as shown in FIG. 16C, and the transistor 33b of the driving means 33 is turned on. Therefore, the voltage between the gate and the source of the switching element 31b becomes zero as shown in FIG. 16 (e), which turns off the switching element 31b in the bridge circuit 31. On the other hand, since the state of the switching element 19a does not change, the switching element 31a maintains the off state as described above. During the period from time t ₃ to time t ₄ , the secondary winding 3 of the transformer 30 is driven by the diode 31c and the parasitic diode 31f of the switching element 31b.
Rectify the output of 0b.

Here, the switching element 31a of the bridge circuit 31 is connected to the switching element 3a from the drive power source 25.
A driving voltage is applied to each of 1b from the driving power source 26, but these are the same as the driving power source 12 of the first embodiment, and are always a constant voltage which is stabilized regardless of the voltage fluctuation of the DC power source 2. Is supplied to the switching elements 31a and 31b even if the input voltage fluctuates.
The gate-source voltages V _GS1 and V _GS2 can always be constant and optimum. As a result, a low voltage drop can be maintained, and a constant minimum required drive power can be suppressed regardless of fluctuations in the input voltage, and a negative voltage can be prevented from being applied. And a low loss rectifier circuit can be constructed.

Example 11. In the above tenth embodiment,
Switching element 3 of bridge circuit 31 connected in series
1a and 31b, and diode 31c connected in series
And 31d are connected in parallel to the secondary winding 30b of the transformer 30, the choke coil 7a of the smoothing filter 7 is connected to the connection point of the switching elements 31a and 31b, and the smoothing filter 7 is connected to the connection point of the diodes 31c and 31d. Although the output terminal 8b is connected via the above, the connection of the bridge circuit 31 may be of another type, and the same effect as that of the above-described embodiment can be obtained.

FIG. 17 shows a DC according to the eleventh embodiment of the present invention.
It is a circuit diagram of a / DC converter. According to the eleventh embodiment, the switching elements 31a and the diodes 31c connected in series and the switching elements 31b and the diodes 31d connected in series in the bridge circuit 31 are connected in parallel to the secondary winding 30b of the transformer 30. The choke coil 7a of the smoothing filter 7 is connected to the connection point of the switching element 31a and the diode 31c, and the output terminal 8b is connected to the connection point of the switching element 31b and the diode 31d via the smoothing filter 7. In addition,
Since the basic operation is the same as that of the tenth embodiment shown in FIG. 15, the description thereof will be omitted.

Example 12. Further, in the tenth embodiment,
At the connection point of the switching elements 31a and 31b of the bridge circuit 31 in which the switching elements 31a and 31b connected in series and the diodes 31c and 31d connected in series are connected in parallel to the secondary winding 30b of the transformer 30. Although the choke coil 7a of the smoothing filter 7 is connected and the output terminal 8b is connected to the connection point of the diodes 31c and 31d via the smoothing filter 7, the connection may be replaced.

FIG. 18 shows a DC according to the twelfth embodiment of the present invention.
It is a circuit diagram of a / DC converter. According to the twelfth embodiment, the choke coil 7a of the smoothing filter 7 is connected to the connection point of the diodes 31c and 31d of the bridge circuit 31, and the output terminal 8b is connected to the connection point of the switching elements 31a and 31b via the smoothing filter 7. Connected. In this case, the two switching elements 31a of the bridge circuit 31
And 31b can be driven by the driving means 32 and 33 having a common ground level, so that the connecting points of the switching elements 31a and 31b are common to the driving means 32 and 33 and the driving power supply 25 as shown in FIG. It is possible to connect to a stabilized earth level, and to supply the driving means 32 and 33 with only one driving power supply 25, which is a stabilized and constant power supply similar to the driving power supply 12 of the first embodiment. It becomes possible to do. Since the basic operation is the same as that of the tenth embodiment shown in FIG. 15, the description thereof will be omitted.

Example 13. In addition, the above Examples 10 to 12
Then, the bridge circuit 31 has two switching elements and two
A mixed bridge composed of two diodes is shown, but a full bridge using four switching elements may be used.
It has the same effect as 1.

FIG. 19 shows a DC according to the thirteenth embodiment of the present invention.
It is a circuit diagram of a / DC converter. In the figure, 31 is four switching elements 31 connected in full bridge.
is a bridge circuit composed of a, 31b, 31g and 31h, and 31i and 31j are switching elements 3
It is a parasitic diode of 1g or 31h. Also, 3
Reference numeral 4 is composed of transistors 34a and 34b and a gate resistor 34c, and is a switching element 31 of the bridge circuit 31.
drive means for driving g, 35 is transistors 35a, 3
5b and a gate resistor 35c, the bridge circuit 3
1 is a driving means for driving the switching element 31h, and 36 is constituted by a driving power supply winding 30e of the transformer 30, diodes 36a and 36b, a choke coil 36c, and a smoothing capacitor 36d, and driving means 34 and 35.
In addition, the drive power source supplies a stabilized constant power source similar to the case of the drive power source 12 of the first embodiment. The transformer 30 is provided with the drive power source winding 30e, and the current transformer 20a as the current detecting means outputs the signal C for controlling the control means 34 in addition to the signal A for controlling the drive means 32. And the current transformer 20b controls the signal B for controlling the drive means 33.
Besides, a signal D for controlling the control means 35 is also output.

In the bridge circuit 31 of the DC / DC converter according to the thirteenth embodiment, the signal A from the current transformer 20a is used.
And the signal C, the driving means 32 simultaneously drives the switching element 31a and the driving means 34 simultaneously drives the switching element 31g, and the driving means 33 drives the switching element 31b by the signals B and D from the current transformer 20b. , The driving means 35 is the switching element 31h
Drive each simultaneously. Since the other basic operations are the same as those in the above-described tenth to twelfth embodiments, the description thereof will be omitted.

Example 14. FIG. 20 shows the first embodiment of the present invention.
4 is a circuit diagram showing a DC / DC converter according to FIG. The fourteenth embodiment is a DC according to the twelfth embodiment shown in FIG.
The drive means 32 and 33 of the / DC converter are shown in FIG.
As in the case of the eighth embodiment shown in FIG.
It is controlled by the signal A and the signal B transmitted by means of the reference numeral 9, and the respective parts are given the same reference numerals as those in the corresponding parts in FIG. 11 or FIG.

FIG. 21 is a waveform diagram for explaining the operation of the DC / DC converter according to the fourteenth embodiment shown in FIG. It should be noted that FIG.
Waveform of voltage V _T1 induced in the next winding 30a ₁ , FIG.
Is the waveform of the drive signal C given to the switching element 19a of the rectangular wave generator 19 from the drive circuit 28a, FIG.
Similarly, the waveform of the drive signal D given to the switching element 19b from the drive circuit 28b is the same as the waveform of the signal A generated in the resistor 29d of the drive signal transmission means 29 in the same figure (d). The waveform of the signal B to be applied, the waveform (f) of FIG. 6 is the waveform of the gate-source voltage V _GS1 of the switching element 31 a of the bridge circuit 31, and the waveform (g) of the same is the gate-source voltage V _{GS2 of the} switching element 31 b. Is the waveform of.

Next, the operation will be described. The drive signal C from the drive circuit 28a is applied to the switching element 19a of the rectangular wave generator 19 as shown in FIG. 21 (b). The period from time t ₁ ~ time t ₂ when the switching element 19a is turned on, the positive direction of voltage as shown in FIG. 21 (a) V _T1
Is induced on the 1 o'clock side of the transformer 30. At this time, the switching element 29b of the drive signal transmission means 29 is also turned on by the drive signal C. Therefore, a positive voltage is induced across the resistor 29d connected to one secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 as shown in FIG. Is transmitted to the drive means 32. In the driving means 32, the signal A turns on the transistor 32ba, and in the bridge circuit 31, the gate of the switching element 31a is biased in the positive direction as shown in FIG. As a result, the switching element 31a is turned on.

On the other hand, during this period, as shown in FIG. 21 (e), the pulse transformer 29a in the drive signal transmission means 29 is used.
The voltage induced in the opposite 29e connected to the other secondary winding of the above becomes a negative voltage, which is transmitted as the signal B to the driving means 33. Since the transistor 33b is turned on by the signal B in the driving means 33, the gate-source voltage of the switching element 31b of the bridge circuit 31 becomes zero as shown in FIG. As a result, the switching element 31b maintains the off state. At that time, in the bridge circuit 31, the diode 31 that is diagonal to the switching element 31a in the ON state is used.
The diode 31c diagonally connected to the switching element 31b which is in the OFF state is non-conductive because the output d of the secondary winding 30b is rectified by d becoming conductive.

When the switching element 19a of the rectangular wave generator 19 is turned off at time t ₂ as shown in FIG. 21 (b), the voltage V _T1 becomes zero as shown in FIG. 21 (a). At that time,
Also in the drive signal transmission means 29, the switching element 29b is turned off by the drive signal C. Therefore, the signal A output from the resistor 29d of one secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 is as shown in FIG.
It becomes zero like. In the driving means 32, the signal A turns on the transistor 32b and the gate-source voltage of the switching element 31a becomes zero as shown in FIG. 21 (f). Therefore, in the bridge circuit 31, the switching element 31a is turned off. Become. On the other hand, during this period,
Since the signal B output from the resistor 29e connected to the other secondary winding of the pulse transformer 29a in the drive signal transmitting means 29 also becomes zero as shown in FIG. 21 (e), the time t ₁
Like the period-time t _2, the switching element 31b of the bridge circuit 31 is kept off. Note that time t
In a period of ₂ to time t _3, rectifying the output of the secondary winding 30b of the transformer 30 by the parasitic diode 31e diode 31d and the switching element 31a.

Further, the drive signal D from the drive circuit 28b is applied to the switching element 19b of the rectangular wave generator 19 as shown in FIG.
Given as 1 (c). Switching element 19b
21 is turned on during the period from time t ₃ to time t _{4 when} is turned on.
A negative voltage V _T1 as shown in (a) is induced on the primary side of the transformer 30. At this time, the switching element 29c of the drive signal transmission means 29 is also turned on by the drive signal D. Therefore, the resistor 2 connected to one of the secondary windings of the pulse transformer 29a in the drive signal transmitting means 29.
A voltage in the positive direction is induced at both ends of 9e as shown in FIG. 21 (e), and this is transmitted to drive means 33 as signal B. In the driving means 33, the transistor 33a is turned on by this signal B, and the gate of the switching element 31b of the bridge circuit 31 is biased in the positive direction as shown in FIG. As a result, the switching element 31b is turned on.

On the other hand, during this period, the drive signal transmitting means 2
The voltage induced in the resistor 29d connected to the other of the secondary windings of the pulse transformer 29a in 9 becomes a negative voltage as shown in FIG. Transmitted. Since the transistor 32b is turned on by the signal A in the driving means 32,
As shown in (f), the gate-source voltage of the switching element 31a of the bridge circuit 31 becomes zero. As a result, the switching element 31a maintains the off state. At that time, in the bridge circuit 31, the diode 31c diagonally connected to the switching element 31b in the ON state is turned on to rectify the output of the secondary winding 30b, and the switching element 31a in the OFF state.
The diode 31d diagonally opposite to is non-conductive.

When the switching element 19b of the rectangular wave generator 19 is turned off at time t ₄ as shown in FIG. 21 (c), the voltage V _T1 becomes zero as shown in FIG. 21 (a). At that time,
In the drive signal transmission means 29, the drive signal D also turns off the switching element 29c. Therefore, the signal B output from the resistor 29e of one of the secondary windings of the pulse transformer 29a in the drive signal transmitting means 29 is as shown in FIG.
It becomes zero like. In the driving means 33, the transistor 33b is turned on by this signal B, and the bridge circuit 31
The voltage between the gate and the source of the switching element 31b becomes zero as shown in FIG. As a result, the switching element 31b is turned off. On the other hand, during this period, the pulse transformer 29a in the drive signal transmission means 29 is
Because even if the signal output from the connection to the other secondary winding resistance 29d A becomes zero as shown in FIG. 21 (e), as with the period of the time t ₁ ~ time t _2, the bridge circuit 31 The switching element 31a of 1 maintains the off state. In addition,
During the period from time t ₃ to time t ₄ , the output of the secondary winding 30b of the transformer 30 is rectified by the diode 31c and the parasitic diode 31f of the switching element 31b.

Here, the switching element 31a and the switching element 31b of the bridge circuit 31 are supplied with a stabilized constant drive voltage from the drive power source 25 in the same manner as the drive power source 12 of the first embodiment. But
Since these supply a constant voltage which is always stabilized irrespective of the voltage fluctuation of the DC power supply 2, even if the input voltage fluctuates, the voltage V _GS1 between the gate and the source of the switching elements 31a and 31b. , V _GS2 can always provide a constant optimum voltage. As a result, a low voltage drop can be maintained, and a constant minimum required drive power can be suppressed regardless of fluctuations in the input voltage, and a negative voltage can be prevented from being applied. And a low loss rectifier circuit can be constructed.

In the fourteenth embodiment, the case where the same bridge circuit as that of the twelfth embodiment shown in FIG. 18 is used as the bridge circuit has been described, but the tenth embodiment shown in FIG. The same mixed bridge as in the case of the eleventh embodiment shown in FIG. 17 may be used, and further the same full bridge as that in the case of the thirteenth embodiment shown in FIG. 19 may be used.

Example 15. 22 shows a first embodiment of the present invention.
FIG. 19 is a circuit diagram showing a DC / DC converter according to No. 5, the same reference numerals as those of the corresponding portions in FIG. In this case, the transformer 30 includes the primary windings 30a ₁ and 30a ₂ , the secondary winding 30b, the drive power source winding 30c, and control windings (windings) 30g and 30h. The driving means 32 and 33 are the control winding 30g.
Alternatively, the switching elements 31a and 31b of the bridge circuit 31 are controlled according to the polarity of the voltage generated at 30h.

FIG. 23 is a waveform diagram for explaining the operation of the DC / DC converter according to the fifteenth embodiment shown in FIG. It should be noted that FIG.
Waveform of voltage V _T1 induced in the next winding 30a ₁ , FIG.
Is a waveform of the voltage V _T2 induced in the control winding 30g of the transformer 30, FIG. 7C is a waveform of the voltage V _T3 induced in the control winding 30h of the transformer 30, and FIG.
Voltage V between the gate and source of the switching element 31a of
The waveform of _GS1 and the same figure (e) shows the switching element 31
It is a waveform of the gate-source voltage V _GS2 of FIG.

Next, the operation will be described. Switching elements 19a of the rectangular wave generator 19 and 19b of periodically turning on / off driving respectively, in a period of time t ₁ ~ time t ₂ when the switching element 19a is turned on, transformer 3
The voltage V in the positive direction as shown in FIG.
_T1 is induced. At that time, the control winding 30g is also shown in FIG.
A positive voltage V _T2 as shown in (b) is induced and sent to the driving means 32. The drive means 32 that has received it is shown in FIG.
As shown in FIG. 3 (d), the gate-source voltage V _GS1 in the positive direction is applied to the switching element 31a of the bridge circuit 31.
give. As a result, the switching element 19a is turned on.

On the other hand, at that time, the control winding 30h is shown in FIG.
As shown in (c), a negative voltage V _T3 is induced and sent to the driving means 33. The driving means 33 having received it, as shown in FIG. 23 (e), sets the gate-source voltage V _GS1 of the switching element 31b of the bridge circuit 31 to zero. As a result, the switching element 31b is turned off. At that time, in the bridge circuit 31, the diode 31d diagonally connected to the switching element 31a in the ON state becomes conductive, and the secondary winding 30b.
The diode 31c that rectifies the output of the diode and is diagonal to the switching element 31b that is in the OFF state is non-conductive.

When the switching element 19a is turned off at time t ₂ , the voltage V _T1 becomes zero and the voltage V _T2 of the control winding 30g and the control winding 30 become as shown in FIG. 23 (a).
The voltage V _{T3 of} h also becomes zero as shown in FIGS. 23 (b) and 23 (c). Therefore, FIG. 23 (d) and FIG.
As shown in (e), the gate-source voltage V _GS1 of the switching element 31a of the bridge circuit 31 and the gate
The voltage V _GS2 between the sources becomes zero. As a result, the switching element 31a is turned off and the switching element 31b is kept off. The time t ₂ ~
During the period of time t _3, the secondary winding 3 is driven by the diode 31d and the parasitic diode 31e of the switching element 31a.
The output of 0b is rectified.

Further, during the period from time t ₃ to time t ₄ when the switching element 19b is on, a negative voltage V _T1 as shown in FIG. 23A is induced on the primary side of the transformer 30. The negative voltage V _T2 as shown in FIG. _23B is also induced in the control winding 30g. This negative voltage V _T2
The driving means 32 having received the voltage sets the gate-source voltage V _GS1 of the switching element 31a of the bridge circuit 31 to zero as shown in FIG. 23 (d). As a result, the switching element 31a maintains the off state as it is.

On the other hand, at that time, the control winding 30h is shown in FIG.
As shown in (c), a positive voltage V _T3 is induced and sent to the driving means 33. The driving means 33 having received it biases the gate-source voltage V _GS1 of the switching element 31b of the bridge circuit 31 in the positive direction as shown in FIG. As a result, the switching element 31b is turned off. At that time, in the bridge circuit 31, the diode 31c diagonally connected to the switching element 31b which is in the ON state becomes conductive.
The diode 31d that rectifies the output of the next winding 30b and is diagonal to the switching element 31a in the off state is non-conductive.

When the switching element 19a is turned off at time t ₄ , the voltage V _T1 becomes zero and the voltage V _T2 of the control winding 30g and the control winding 30 as shown in FIG. 23 (a).
The voltage V _{T3 of} h also becomes zero as shown in FIGS. 23 (b) and 23 (c). Therefore, FIG. 23 (d) and FIG.
As shown in (e), the gate-source voltage V _GS1 of the switching element 31a of the bridge circuit 31 and the gate
The voltage V _GS2 between the sources becomes zero. As a result, the switching element 31a remains off and the switching element 31b is turned off. In the period from time t ₃ ~ time t _4, performs rectification output of the secondary winding 30b by diode 31c and 31d, the parasitic diode 31f of the switching element 31b.

Here, the switching element 31a and the switching element 31b of the bridge circuit 31 are supplied with a stabilized constant drive voltage from the drive power supply 25 in the same manner as the drive power supply 12 of the first embodiment. These supply a constant voltage which is always stabilized irrespective of the voltage fluctuation of the DC power supply 2, so that even if the input voltage fluctuates, the voltage V _GS1 between the gate and source of the switching elements 31a and 31b. , V _GS2 can always provide a constant optimum voltage. As a result, a low voltage drop can be maintained, and a constant minimum required drive power can be suppressed regardless of fluctuations in the input voltage, and a negative voltage can be prevented from being applied. And a low loss rectifier circuit can be constructed.

In the fifteenth embodiment, the case where the same bridge circuit as that of the twelfth embodiment shown in FIG. 18 is used as the bridge circuit has been described, but the tenth embodiment shown in FIG. A mixed bridge similar to that of the eleventh embodiment shown in FIG. 17 may be used, and further a similar full bridge to that of the thirteenth embodiment shown in FIG. 19 may be used.

In the tenth to fifteenth embodiments, the push-pull converter is used as the rectangular wave generator 19 which uses the DC power supply 2 as a power source and generates a rectangular wave signal having positive, negative and zero periods. However, as in the case of the sixth and seventh embodiments, a full bridge converter, a half bridge converter or the like may be used.

[0130]

As described above, according to the first aspect of the present invention, as the rectifying means on the secondary side of the Ichikoku forward converter having the first switching element on the primary side, the second and the third rectifying means are provided. Using two switching elements, the current detection means for detecting the current of the first switching element is provided,
A driving means for operating the third switching element to conduct during the period when the current flows, and the second switching element to conduct during the period when the current does not flow;
Since the drive power supply is configured to supply a constant voltage stabilized by rectifying and smoothing the output of the drive power supply winding of the transformer, the drive power supply is used as the secondary side rectification means. Since the ON resistance values of the two switching elements can be kept low at all times, the voltage drop can be reduced, and it is possible to suppress the required minimum drive power regardless of fluctuations in the input voltage. Since it does not need to be applied, the driving power is about half compared to the case of charging / discharging in both positive and negative directions.
There is an effect that a DC converter can be obtained.

According to the second aspect of the present invention, as the rectification means on the secondary side of the Ichikoku forward converter having the first switching element on the primary side, the second and the third rectifiers are provided.
A drive signal transmission means for transmitting the drive signal of the first switching element is provided by using two switching elements, and the third switching element is turned on during the period in which the drive signal is outputting the ON signal, and the OFF signal is transmitted. During the period of output, a drive means for operating the second switching element to conduct is provided, and the drive power supply stabilizes by rectifying and smoothing the output of the drive power supply winding of the transformer. Since it is configured to supply a constant voltage, the ON resistance value of the two switching elements used as the rectifying means on the secondary side can always be kept low, so that the voltage drop can be reduced and fluctuations in the input voltage can be prevented. Therefore, it is possible to suppress to a certain minimum required drive power, and since it is not necessary to apply a negative voltage, the drive power is charged and discharged in both positive and negative directions. Since about half compared to the case, it can be a very small driving power, the effect of the DC / DC converter with a low-loss rectifier circuit is obtained.

Further, according to the invention of claim 3, as the rectifying means on the secondary side of the single-stone forward converter having the first switching element on the primary side, the second and third second rectifying means are provided.
The three switching elements are used to detect the voltage generated in the transformer winding, and the detected voltage is the third switching during the period of the same polarity as the voltage generated in the transformer winding when the first switching element is conducting. A drive unit is provided which makes the element conductive and operates so as to make the second switching element conductive during a period of reverse polarity or zero voltage. The drive power source rectifies the output of the winding for the drive power source of the transformer to the drive unit. Since it is configured to supply a constant voltage stabilized by smoothing, the on-resistance value of the two switching elements used as the rectifying means on the secondary side can always be kept low, so that the voltage drop is low. In addition, it is possible to suppress the required minimum drive power regardless of the fluctuation of the input voltage, and it is not necessary to apply a negative voltage. Since about half compared to the case of charging and discharging in both positive and negative directions, it can be a very small driving power, the effect of the DC / DC converter with a low-loss rectifier circuit is obtained.

Further, according to the invention of claim 4, the multi-stone type D
When a rectangular wave signal is applied from the rectangular wave generator to the primary side of the transformer of the C / DC converter, the output obtained from the secondary winding with the center tap is rectified by a double-wave rectification circuit with two switching elements. Then, a current detecting means for detecting a current flowing in the primary winding of the transformer is provided, and one switching element is provided during a period in which a positive current flows when a positive voltage is applied to the primary winding. Only the other switching element becomes non-conducting during the period when the negative current flowing when the negative voltage is applied is provided with the driving means. Since the means is configured to supply a constant voltage stabilized by rectifying and smoothing the output of the transformer drive power source winding, it is used as a secondary side rectifying means. Since the ON resistance of the two switching elements can be kept low at all times, the voltage drop can be reduced, and it is possible to suppress to a constant minimum required drive power regardless of fluctuations in the input voltage. Since it does not need to be used, the driving power is about half compared to the case of charging and discharging in both positive and negative directions, so that the driving power can be made very small and a DC / DC converter having a low loss rectifying circuit can be obtained. There is.

According to the fifth aspect of the present invention, the rectangular wave generator having two switching elements configured in the push-pull converter positively uses DC as a power source,
Since the rectangular wave signal having negative and zero periods is generated and applied to the primary winding of the transformer, the rectangular wave generator can be realized by an extremely simple circuit.

According to the invention described in claim 6, the rectangular wave generator having four switching elements configured in the full-bridge converter positively uses DC as a power source,
Since a rectangular wave signal having a period of negative and zero is generated and applied to the primary winding of the transformer, the circuit configuration of the rectangular wave generator is slightly complicated, but
There is no need to use a secondary winding having a center tap, and there is an effect that only one current detecting means is required.

According to the seventh aspect of the invention, the rectangular wave generator including the two switching elements and the two capacitors configured in the half-bridge converter,
Since a rectangular wave signal having positive, negative, and zero periods is generated using direct current as a power source and is applied to the primary winding of the transformer, it is possible to use a center tap transformer for the primary winding. In addition, there is an effect that the circuit configuration of the rectangular wave generator can be simplified as compared with the one configured as the full bridge converter while maintaining the effect that only one current detection unit is required.

According to the invention of claim 8, the multi-stone type D
When a rectangular wave signal is applied from the rectangular wave generator to the primary side of the transformer of the C / DC converter, the output obtained from the secondary winding with the center tap is rectified by a double-wave rectification circuit with two switching elements. However, drive signal transmission means for transmitting the drive signal of the rectangular wave generator is provided, and in synchronization with the signal transmitted thereby, only one of the switching elements becomes non-conducting while it is in the positive direction, and the negative signal is generated. Direction is provided with a driving means that operates so that only the other switching element becomes non-conductive, and the driving power supply stabilizes by rectifying and smoothing the output of the winding for the driving power supply of the transformer. Since it is configured to supply a constant voltage that is generated, the ON resistance values of the two switching elements used as the rectifying means on the secondary side can be kept low at all times. It is possible to reduce the drop, and it is possible to suppress to a certain minimum required drive power regardless of the fluctuation of the input voltage. Furthermore, since it is not necessary to apply a voltage in the negative direction, the drive power can be charged and discharged in both positive and negative directions. Since it is about half that of the DC / DC converter having a low loss rectifier circuit, the driving power can be made extremely small.

Further, according to the invention of claim 9, the multi-stone type D
When a rectangular wave signal is applied from the rectangular wave generator to the primary side of the transformer of the C / DC converter, the output obtained from the secondary winding with the center tap is rectified by a double-wave rectification circuit with two switching elements. Then, the voltage generated in the transformer winding is detected so that only one switching element is non-conducting during the positive direction of the detected voltage and only the other switching element is non-conducting during the negative direction. Since a driving power supply is provided and a constant voltage stabilized by rectifying and smoothing the output of the winding for the driving power supply of the transformer is supplied from the driving power supply to the driving power supply, the secondary side 2 used as rectifying means
Since the ON resistance of the two switching elements can be kept low at all times, the voltage drop can be reduced, and it is possible to suppress to a constant minimum required drive power regardless of fluctuations in the input voltage. Since it does not need to be used, the driving power is about half compared to the case of charging and discharging in both positive and negative directions, so that the driving power can be made very small and a DC / DC converter having a low loss rectifying circuit can be obtained. There is.

According to the tenth aspect of the present invention, when the rectangular wave signal is applied from the rectangular wave generator to the primary side of the transformer of the multi-stone DC / DC converter, the output obtained from the secondary winding is obtained. , Current switching means for detecting the current flowing in the primary winding of the transformer is rectified by using a bridge circuit consisting of four switching elements in full bridge connection or two switching elements in mixed bridge connection and two diodes. During a period in which a positive direction current flows when a positive direction voltage is applied to the primary winding, only one pair of switching elements of two diagonal sides of the bridge circuit conducts. During a period in which a negative-direction current that flows when a negative-direction voltage is applied, only a switching device of the other pair is provided with a driving unit that operates so that the driving power supply Since a constant voltage stabilized by rectifying and smoothing the output of the drive power source winding of the transformer is supplied to this driving means, the two switching devices used as the rectifying means on the secondary side are provided. Since the on-resistance value of the element can be kept low at all times, the voltage drop can be reduced, and it is possible to suppress to a constant minimum required drive power regardless of the fluctuation of the input voltage. Since the driving power is about half as compared with the case of charging / discharging in both positive and negative directions, it is possible to reduce the driving power to an extremely small value and to have a low loss rectifier circuit.
There is an effect that a C / DC converter can be obtained.

According to the invention described in claim 11,
A bridge circuit is formed by two switching elements and two diodes connected in a mixed bridge, and a secondary winding of a transformer is connected to the connection point between the switching elements and the diodes.
A smoothing filter is connected to the connection point of one switching element and the connection point of two diodes, the drive power source and the ground level of the two drive means are made common, and it is connected to the connection point of the two switching elements. Because I did
There is an effect that the power supply to the two drive means can be performed by one drive power supply.

According to the twelfth aspect of the invention, when the rectangular wave signal is applied from the rectangular wave generator to the primary side of the transformer of the multi-stone DC / DC converter, the output obtained from the secondary winding is A drive signal transmitting means for transmitting a drive signal of the rectangular wave generator, which is rectified by using a bridge circuit including four switching elements connected in a full bridge or two switching elements connected in a mixed bridge and two diodes, In synchronization with the signal transmitted by it,
During the period when it is in the positive direction, only one switching element of the two diagonal sides of the bridge circuit conducts,
During the period in the negative direction, it is provided with a driving means that operates so that only the other pair of switching elements becomes conductive, and the driving power supply stabilizes by rectifying and smoothing the output of the winding for the driving power supply of the transformer. Since it is configured to supply a uniform constant voltage, the ON resistance values of the two switching elements used as the rectifying means on the secondary side can always be kept low, so that the voltage drop can be reduced and the input voltage It is possible to suppress to a certain minimum required drive power regardless of fluctuations, and since it is not necessary to apply a voltage in the negative direction, the drive power is about half compared to the case of charging and discharging in both positive and negative directions. There is an effect that a DC / DC converter having a low loss rectifier circuit can be obtained with a very small drive power.

According to the invention of claim 13, when the rectangular wave signal is applied from the rectangular wave generator to the primary side of the transformer of the multi-stone DC / DC converter, the output obtained from the secondary winding is Rectification is performed using a bridge circuit consisting of four switching elements in full bridge connection or two switching elements in mixed bridge connection and two diodes, and the voltage generated in the transformer winding is detected, and the detected voltage is in the positive direction. Of the bridge circuit, only one pair of switching elements of the two diagonal sides of the bridge circuit conducts, and during the negative direction, only the other pair of switching elements conducts. Since the driving power supply supplies the driving means with a constant voltage stabilized by rectifying and smoothing the output of the winding for the driving power supply of the transformer, Since the ON resistance values of the two switching elements used as the rectifying means on the secondary side can be kept low at all times, the voltage drop can be reduced and the drive power can be suppressed to a constant minimum required power regardless of the fluctuation of the input voltage. Since it is not necessary to apply a voltage in the negative direction, the driving power is about half compared to the case of charging and discharging in both positive and negative directions. There is an effect that a DC / DC converter having a rectifying circuit can be obtained.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a DC / DC converter according to a first embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 3 is a circuit diagram showing a DC / DC converter according to a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a DC / DC converter according to a third embodiment of the present invention.

FIG. 5 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 6 is a circuit diagram showing a DC / DC converter according to a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a DC / DC converter according to a fifth embodiment of the present invention.

FIG. 8 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 9 is a circuit diagram showing a DC / DC converter according to a sixth embodiment of the present invention.

FIG. 10 is a circuit diagram showing a DC / DC converter according to a seventh embodiment of the present invention.

FIG. 11 is a circuit diagram showing a DC / DC converter according to an eighth embodiment of the present invention.

FIG. 12 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 13 is a circuit diagram showing a DC / DC converter according to a ninth embodiment of the present invention.

FIG. 14 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 15 is a circuit diagram showing a DC / DC converter according to a tenth embodiment of the present invention.

FIG. 16 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 17 is a circuit diagram showing a DC / DC converter according to an eleventh embodiment of the present invention.

FIG. 18 is a circuit diagram showing a DC / DC converter according to a twelfth embodiment of the present invention.

FIG. 19 is a circuit diagram showing a DC / DC converter according to a thirteenth embodiment of the present invention.

FIG. 20 is a circuit diagram showing a DC / DC converter according to a fourteenth embodiment of the present invention.

FIG. 21 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 22 is a circuit diagram showing a DC / DC converter according to a fifteenth embodiment of the present invention.

FIG. 23 is a waveform diagram for explaining the circuit operation of the above embodiment.

FIG. 24 is a circuit diagram showing a conventional DC / DC converter.

FIG. 25 is a circuit diagram showing a conventional DC / DC converter.

[Explanation of symbols]

1,18,30 transformers, 1a, 18a, 18a ₁ ,
18a ₂ , 30a ₁ , 30a ₂ primary winding, 1b, 18
d ₁ , 18d ₂ , 30b secondary winding, 1d, 18i, 1
8j, 30g, 30h Control winding (winding), 1e, 1
f, 18g, 18h, 30c, 30d, 30e Drive power source winding, 2 DC power source, 3 first switching element, 5 2nd switching element, 6 3rd switching element, 7 smoothing filter, 10, 20, 20a, 20
b Current transformer (current detecting means) 11, 23, 24, 32
~ 35 drive means, 12, 12A, 12B, 25, 2
6,36 driving power source, 15,29 driving signal transmitting means,
18e center tap, 18f _1, 18f ₂ taps, 19 rectangular wave generator, 19a to 19h, 21,2
2, 31a, 31b, 31g, 31h switching elements, 19i, 19j capacitors, 31 bridge circuits, 31c, 31d diodes.

Claims (13)

[Claims] 1. A transformer having a primary winding and a secondary winding, and a transformer which is connected in series with a DC power source and is connected to the primary winding of the transformer to periodically turn on / off the DC power source. One switching element, second and third switching elements connected in series with each other and connected to the secondary winding of the transformer, and smoothing in which the second switching element is connected in parallel to the input side thereof. Filter and the first
Current detecting means for detecting a current flowing through the switching element, and the third switching element is conducting during the period when the current detecting means detects that the current is flowing, and the current is not flowing. Is detected, the second switching element is driven so as to conduct, and the transformer has a drive power supply winding, and the output of the drive power supply winding is rectified and smoothed. A drive power supply for supplying a voltage to the drive means
C / DC converter. 2. A transformer having a primary winding and a secondary winding, and a transformer which is connected in series with a DC power source and is connected to the primary winding of the transformer to periodically turn on / off the DC power source. 1 switching element, second and third switching elements connected in series with each other to the secondary winding of the transformer, and a smoothing circuit in which the second switching element is connected in parallel to the input side thereof. Filter and the first
Driving signal transmitting means for transmitting the driving signal of the switching element, and a period in which the driving signal is an ON signal in synchronization with the driving signal of the first switching element transmitted by the driving signal transmitting means. The switching device of No. 3 is conducting, and the driving means for operating so that the second switching device is conducting during the period when it is an OFF signal, and the transformer has a drive power supply winding, and the drive power supply winding is provided. A DC / DC converter comprising: a drive power supply that rectifies the output of the line and supplies a smoothed voltage to the drive means. 3. A transformer having a primary winding and a secondary winding, and a transformer which is connected in series with a DC power source and is connected to the primary winding of the transformer to periodically turn on / off the DC power source. 1 switching element, second and third switching elements connected in series with each other to the secondary winding of the transformer, and a smoothing circuit in which the second switching element is connected in parallel to the input side thereof. During a period in which the polarity of the voltage generated in the filter and the winding of the transformer is generated when the first switching element is in conduction, the third switching element is in conduction and the polarity is reverse to that or zero voltage. Has a driving means for operating the second switching element so that the second switching element is conductive, and a winding for driving power supply in the transformer, and rectifies an output of the winding for driving power supply to smooth the voltage. A DC / DC converter including a drive power supply that supplies the drive means. 4. Two with primary winding and center tap
A transformer with a secondary winding and positive, negative, and
A rectangular wave generator that generates a rectangular wave signal having a zero period and applies it to the primary winding of the transformer, and one end of the rectangular wave generator are connected to each other, and the other end is the secondary of the transformer. Two switching elements connected to each tap other than the center tap of the winding, and an input side thereof is connected between a connection point of the two switching elements and a center tap of the secondary winding of the transformer. A filter, a current detecting means for detecting a current flowing through the primary winding of the transformer, and a current flowing when a positive voltage is applied to the primary winding of the transformer by the current detecting means. During the period, only one of the two switching elements becomes non-conductive, and during the period when a current flowing when a negative voltage is applied is detected,
Driving means for operating only the other of the two switching elements to be non-conductive, and a drive power supply winding in the transformer, the output of the drive power supply winding is rectified and smoothed voltage A DC / DC converter including a drive power supply that supplies the drive means. 5. The DC / DC converter according to claim 4, wherein the rectangular wave generator is configured as a push-pull converter using two switching elements. 6. The DC / DC converter according to claim 4, wherein the rectangular wave generator is configured as a full-bridge converter using four switching elements. 7. The DC / DC converter according to claim 4, wherein the rectangular wave generator is configured as a half-bridge converter using two switching elements and two capacitors. 8. A secondary winding having a primary winding and a center tap.
A transformer with a secondary winding and positive, negative, and
A rectangular wave generator that generates a rectangular wave signal having a zero period and applies it to the primary winding of the transformer, and one end of the rectangular wave generator are connected to each other, and the other end is the secondary of the transformer. Two switching elements connected to each tap other than the center tap of the winding, and an input side thereof is connected between a connection point of the two switching elements and a center tap of the secondary winding of the transformer. In synchronization with the filter, the drive signal transmitting means for transmitting the drive signal of the rectangular wave generator, and the drive signal transmitted by the drive signal transmitting means, the two switching operations are performed during a period in which the signal is in the positive direction. Driving means for operating such that only one of the two switching elements is non-conductive during a period in which only one of the switching elements is non-conductive and the other of the two switching elements is in a negative direction; Transformer has a winding drive power source, DC / D with a drive power supplied to the smoothed voltage by rectifying an output of the driving power source for winding the driving means
C converter. 9. A primary winding and two with a center tap
A transformer with a secondary winding and positive, negative, and
A rectangular wave generator that generates a rectangular wave signal having a zero period and applies it to the primary winding of the transformer, and one end of the rectangular wave generator are connected to each other, and the other end is the secondary of the transformer. Two switching elements connected to each tap other than the center tap of the winding, and an input side thereof is connected between a connection point of the two switching elements and a center tap of the secondary winding of the transformer. Only one of the two switching elements is non-conducting during the period when the voltage generated in the filter and the winding of the transformer is in the positive direction, and one of the two switching elements is in the negative direction during the period. Driving means for operating so that only the other side is non-conducting, and a winding for driving power supply in the transformer, and the driving means for rectifying and smoothing the output of the winding for driving power supply. DC with a driving power supply
/ DC converter. 10. A transformer having a primary winding and a secondary winding, and a rectangular wave signal having positive, negative, and zero periods generated by using a direct current as a power source and applying it to the primary winding of the transformer. And a bridge circuit formed by four switching elements in full bridge connection, or two switching elements in mixed bridge connection and two diodes, and connected to the secondary winding of the transformer. , A smoothing filter whose input side is connected to the bridge circuit, a current detecting means for detecting a current flowing in the primary winding of the transformer, and a positive voltage applied to the primary winding of the transformer by the current detecting means. During the period in which the current flowing when is applied is detected, only one of the switching elements of one of the two diagonal sides of the bridge circuit conducts, and the negative side Drive means for operating so that only the switching element of the other pair of the two diagonal sides of the bridge circuit is conductive during the period in which the current flowing when the opposite voltage is applied is detected, A DC / DC converter comprising: a drive power supply winding in the transformer; and a drive power supply that rectifies an output of the drive power supply winding and supplies a smoothed voltage to the drive means. 11. A secondary winding of the transformer is connected in parallel with two switching elements and two diodes each connected in series, and a connection point of the two switching elements and a connection point of the two diodes are connected. The bridge circuit is configured by a mixing bridge in which the input side of the smoothing filter is connected, and the ground level of the driving means and the driving power source is made common, and the connection point of two switching elements of the bridge circuit is made common. 11. The DC / D according to claim 10, wherein the DC / D is connected to a ground level connected to the ground.
C converter. 12. A transformer having a primary winding and a secondary winding, and a rectangular wave signal having positive, negative, and zero periods generated by using a direct current as a power source and applying it to the primary winding of the transformer. And a bridge circuit formed by four switching elements in full bridge connection, or two switching elements in mixed bridge connection and two diodes, and connected to the secondary winding of the transformer. , A smoothing filter whose input side is connected to the bridge circuit, drive signal transmitting means for transmitting a drive signal of the rectangular wave generator, and the drive signal transmitted by the drive signal transmitting means in synchronization with During the period when the signal is in the positive direction, only the switching element of one of the two pairs of diagonal sides of the bridge circuit conducts, and during the period when the signal is in the negative direction, A drive unit that operates so that only the other pair of switching elements of the two diagonal sides of the bridge circuit are turned on, and the transformer has a drive power supply winding. D including a driving power supply for rectifying the output and smoothing the voltage to the driving means
C / DC converter. 13. A transformer having a primary winding and a secondary winding, and a rectangular wave signal having positive, negative and zero periods generated by using a direct current as a power source and applying the rectangular wave signal to the primary winding of the transformer. And a bridge circuit formed by four switching elements in full bridge connection, or two switching elements in mixed bridge connection and two diodes, and connected to the secondary winding of the transformer. , A smoothing filter whose input side is connected to the bridge circuit, and a switching of one of two diagonal sides of the bridge circuit during a period in which the voltage generated in the winding of the transformer is in the positive direction. Only the element conducts, and during the period in which it is in the negative direction, it operates so that only the switching element of the other pair of the two diagonal sides of the bridge circuit conducts. A DC / DC converter comprising: a drive unit; and a drive power supply winding in the transformer, and a drive power supply that rectifies an output of the drive power supply winding and supplies a smoothed voltage to the drive unit.