JP2003088118A - Resonance dc-dc converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resonance DC-DC converter capable of supplying heavy current to load side even if DC power supply of low voltage is used. SOLUTION: Direct current supplied from a DC power supply E is converted into alternating current of small current and high voltage by a DC-AC conversion circuit 15. The alternating current of small current and high voltage from a DC-AC conversion circuit 15 is inputted into the primary winding of a leakage transformer T2 through a capacitor to induce alternating current to a secondary winding, so that the alternating current from the secondary winding of the leakage transformer T2 is rectified and smoothed by an output circuit 13 to output DC voltage and generate a gate driving signal for controlling the DC-AC conversion circuit 15 corresponding to DC voltage from the output circuit 13 in a control circuit 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resonance type D capable of supplying a large current to the load side even if the DC power source has a low voltage.
The present invention relates to a C-DC converter.

[0002]

2. Description of the Related Art In recent years, a resonance type DC-DC converter having excellent characteristics such as high conversion efficiency and low noise has been developed. FIG. 8 shows a half-bridge type current resonance voltage quasi-resonance type DC-DC converter 101 known as a type of resonance type DC-DC converter.

The operation of the DC-DC converter 101 will be described below with reference to the timing chart shown in FIG. First, the DC power source E is the DC-DC converter 10
When it is turned on, the negative input terminal of the operational amplifier OP1 provided in the control circuit 11 is 0V, so that the operational amplifier O1
The maximum level error voltage is output from P1 to the VCO, and the gate drive signal 1 as shown in FIG. 8 is output from the VCO to the gate of the switching element Q11.

At the timing t1, the drain-source voltage Vds1 of the switching element Q11 becomes 0 V due to voltage quasi-resonance due to the inductance of the capacitor C11 and the primary winding P11. At this time, the gate drive signal 1 is supplied to the switching element Q11, and the switching element Q11 is turned on.

As a result, the drain current Id1 from the DC power source E is drain-source of the switching element Q11,
From transformer T11 to half bridge capacitor C13
Through to GND. At this time, the transformer T11
Since magnetic energy is induced in the secondary winding S11, the output voltage is output to the secondary side after being rectified and smoothed by the diode D11 and the capacitor C14.

In the DC-DC converter 101,
Leakage inductance Lo of the transformer T11
And the half bridge capacitor C13 cause series resonance, so that a drain current Id having a sinusoidal waveform as shown in FIG.
A waveform of 1 appears. At the same time, an exciting current due to the inductance of the primary winding P11 is superimposed.

Next, 2 is applied to the minus input terminal of the operational amplifier OP1.
Since the output voltage on the next side is input, the error voltage is output from the operational amplifier OP1 to the VCO. Next, the gate drive signal 2 having a phase substantially opposite to that of the gate drive signal 1 is output from the VCO to the gate of the switching element Q12. Here, at the timing t3 to t4, the switching element Q12 outputs the gate drive signal 2 Accordingly, the drain-source voltage Vds2 becomes 0V by turning on. The drain current Id2 flows from the transformer T11 to the half-bridge capacitor C13 via the drain-source of the switching element Q12 and GND. At this time, since magnetic energy is induced in the secondary winding S12 of the transformer T11, it is rectified and smoothed by the diode D12 and the capacitor C14, and the output voltage is output to the secondary side. By repeating the above-mentioned operation, the output voltage on the secondary side is increased and then stabilized.

[0008]

By the way, a film-structured capacitor is generally used as the half-bridge capacitor C13 used for the above-mentioned resonance. However, since the film thickness is structurally thin, There is a limit to the allowable current. Therefore, the half bridge capacitor C13 used for resonance is suitable for operating at high voltage and small current.

Therefore, in the case of the half bridge type DC-DC converter 101 as described above, the DC power source E side is set to a high voltage, and a small current is allowed to flow in the transformer T11 and the half bridge capacitor C13. This half bridge type DC-DC converter 101 is
The DC power supply E side can be set to a low voltage only when the load power is small and the primary side current is small.

However, when the DC power source E side has a low voltage, or when the load power is large and, for example, the primary current requires a large current of 10 A or more, the resonance type D as described above is used.
There is a problem that a C-DC converter cannot be adopted. Therefore, it has been desired to develop a resonance type DC-DC converter that can operate even when the DC power source E side has a low voltage.

The present invention has been made in view of the above,
An object of the invention is to provide a resonance type DC-DC converter which can be configured even when a low voltage DC power supply is used.

[0012]

The invention according to claim 1 is
In order to solve the above problems, a direct current supplied from a direct current power source is converted from this direct current into a small current / high voltage alternating current-
An AC conversion circuit and a leakage transformer that inputs a small current / high voltage AC from the DC-AC conversion circuit to the primary winding through a resonance capacitor to induce an AC in the secondary winding.
An output circuit that rectifies and smoothes the alternating current from the secondary winding of the leakage transformer and outputs a direct current voltage, and a control circuit that generates a control signal for controlling the direct current-alternating current conversion circuit according to the direct current voltage from the output circuit. The point is to have and.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, the DC-AC conversion circuit is turned on / off alternately according to a control signal from the control circuit. An element, a primary winding provided with a first tap, a center tap and a second tap, and a secondary winding provided with a first tap and a second tap, A transformer for stepping up the input AC voltage and inducing it in the secondary winding, and connecting the first tap of the primary winding of the transformer in series with the first switching element,
The second tap of the primary winding of the transformer is connected in series to the second switching element, and the center tap of the primary winding of the transformer is connected to the DC power source. The first tap of the winding and the first tap of the primary winding of the leakage transformer are connected via a resonance capacitor, and the second tap of the secondary winding of the transformer and the first of the leakage transformer are connected. The secondary winding of the transformer is connected to the secondary tap, and the AC voltage output from the secondary winding of the transformer is resonated by the leakage inductance of the leakage transformer and the resonance capacitor to the primary winding of the leakage transformer. The point is to enter.

According to a third aspect of the present invention, in order to solve the above-mentioned problems, the DC-AC conversion circuit is alternately turned on / off in response to a control signal from the control circuit. An element and a winding provided with a first tap, a center tap, and a second tap, wherein the first tap of the winding is connected in series to the first switching element, and the second tap is connected. A second tap of the winding is connected in series to a switching element, a center tap of the winding is connected to the DC power supply, a first tap of the winding and a primary winding of the leakage transformer. The second tap of the winding is connected to the first tap of
Is connected to the second tap of the primary winding of the leakage transformer, and the AC voltage output from the winding is resonated by the leakage inductance of the leakage transformer and the resonance capacitor, and The point is to input to the next winding.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problems, the DC-AC conversion circuit is turned on / off alternately according to a control signal from the control circuit. An element, a first winding provided with a first tap, a center tap and a second tap, a second winding provided with a third tap and a fourth tap and continuously wound with the first winding And an automatic transformer having a winding, and connecting a first tap of a first winding and a fourth tap of a second winding of the automatic transformer in series with the first switching element. Then, the second tap of the first winding of the autotransformer is connected in series to the second switching element, and the center tap of the first winding of the autotransformer is connected to the DC power supply. , The third winding of the second winding of the autotransformer Of-up and the leakage transformer 1
The first tap of the next winding is connected via a resonance capacitor, the center tap of the first winding of the autotransformer is connected to the second tap of the primary winding of the leakage transformer, The gist is that the AC voltage output from the second winding of the autotransformer is resonated by the leakage inductance of the leakage transformer and the resonance capacitor and is input to the primary winding of the leakage transformer.

According to a fifth aspect of the present invention, in order to solve the above problems, the DC-AC conversion circuit is turned on / off alternately according to a control signal from the control circuit. An element, a first winding provided with a first tap, a center tap, and a second tap; a third winding provided with a third tap, a center tap, and a fourth tap, and continuously wound with the first winding; An automatic transformer having a second winding, a center tap of the first winding of the autotransformer is connected in series to the first switching element, and the center tap of the first switching element is connected to the second switching element. Connect the center tap of the second winding of the autotransformer in series,
The first winding of the first winding of the autotransformer is connected to the DC power supply.
And the fourth tap of the second winding are connected, and the third tap of the second winding of the autotransformer and the first tap of the primary winding of the leakage transformer are used for resonance. A first tap of the autotransformer, a second tap of the first winding of the autotransformer, and a second tap of the primary winding of the leakage transformer; The AC voltage output from the winding is resonated by the leakage inductance of the leakage transformer and the resonance capacitor, and
The point is to input to the next winding.

According to a sixth aspect of the invention, in order to solve the above-mentioned problems, the first and second switching elements are field effect transistors, and the second and third switching elements are connected between a drain terminal and a source terminal. And a second inductor and a third inductor, respectively.
The gist is to alternately resonate with the capacitor of.

In order to solve the above-mentioned problems, a seventh aspect of the present invention includes a non-leakage transformer having no leakage, instead of the leakage transformer.
Second tap of next winding and 1 of the non-leakage transformer
The gist is to connect an inductance between the second winding and the second tap.

In order to solve the above-mentioned problems, the invention according to claim 8 is provided with a non-leakage transformer having no leakage, instead of the leakage transformer, and
Second tap of next winding and 1 of the non-leakage transformer
The gist is to connect an inductance between the second winding and the second tap.

In order to solve the above-mentioned problems, a ninth aspect of the present invention includes a non-leakage transformer that does not leak, in place of the leakage transformer, and a center tap of the primary winding of the autotransformer and the non-leakage transformer. The gist is to connect an inductance to the second tap of the primary winding of the transformer.

According to a tenth aspect of the invention, in order to solve the above-mentioned problems, a leakage-free non-leakage transformer is provided in place of the leakage transformer, and a second tap of the first winding of the autotransformer is provided. The gist of the invention is to connect an inductance to the second tap of the primary winding of the non-leakage transformer.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a diagram showing a detailed configuration of a resonance type DC-DC converter 10 according to a first embodiment of the present invention. Hereinafter, referring to the circuit diagram shown in FIG.
The configuration of the resonance type DC-DC converter 10 will be described.

The DC-AC conversion circuit 15 is provided with switching elements Q1 and Q2 and a transformer T1 for converting a DC voltage supplied from the DC power source E into a small current / high voltage AC. The DC power source E is connected to the center taps Tpc of the primary windings P1 and P2 of the transformer T1,
The switching element Q is attached to the tap Tp1 of the primary winding P1.
The drain of 1 is connected, and the source of this element Q1 is connected to the GND side of the DC power source E. Also, the primary winding P
The drain of the switching element Q2 is connected to the tap Tp2 of No. 2, and the source of this element Q2 is G of the DC power supply E.
It is connected to the ND side.

Tap Tp of the secondary winding S1 of the transformer T1
1 is connected to the tap Tp1 of the primary winding P5 of the leakage transformer T2 via the resonance capacitor C1, and the tap Tp2 of the secondary winding S1 of the transformer T1 and the primary winding P5 of the leakage transformer T2. The tap Tp2 is directly connected.

Secondary winding S5 of leakage transformer T2
The taps Tp1 and Tp2 of S6 are diode D
Capacitor C3 and (+) used for smoothing via 1 and D2
The center taps Tpc of the secondary windings S5 and S6 of the leakage transformer T2 are connected to the output terminal, and are connected to the capacitor C3 and the (−) output terminal.

The inter-terminal voltage of the resistor R11 connected to both output terminals is input to the input resistor R1 of the control circuit 11, and the above-mentioned output voltage Vo of the (+) output terminal is (-) of the operational amplifier OP1. The input voltage is input to the input terminal, and the reference voltage Vref is input to the (+) input terminal of the operational amplifier OP1. The operational amplifier OP1 detects the difference between the output voltage Vo and the reference voltage Vref as an error voltage and supplies the error voltage to the VCO. The VCO outputs two types of gate drive signals Vg1 and Vg2 having substantially opposite phases according to the error voltage. They are generated and output to the gates of the switching elements Q1 and Q2, respectively.

In the present embodiment, the DC voltage E is treated as a power source that can take out a low voltage and a large current, and the secondary winding S1 of the transformer T1 and the leakage transformer T2 have a voltage of 1.
It is assumed that a high voltage / small current appears in the secondary winding P5 and a low voltage / large current can be taken out from the secondary windings S5, S6 of the leakage transformer T2.

Next, the operation of the resonance type DC-DC converter 10 will be described with reference to the timing chart shown in FIG. First, when the DC power supply E is turned on to the DC-DC converter 10, since the negative input terminal of the operational amplifier OP1 provided in the control circuit 11 is 0 V, the operational amplifier OP1 outputs the maximum level error voltage to the VCO,
Further, if the gate drive signal Vg1 as shown in FIG.
It is output from O to the gate of the switching element Q1.

At timing t1, the drain-source voltage Vds1 of the switching element Q1 becomes 0V. At this time, the gate drive signal V is applied to the switching element Q1.
The switching element Q1 is turned on by supplying g1.
As a result, the drain current Id1 from the DC power source E flows from the center tap Tpc of the primary winding of the transformer T1 and the tap Tp1 of the primary winding P1 to the GND via the drain-source of the switching element Q1.

At this time, magnetic energy is induced in the secondary winding S1 of the transformer T1.
From the tap Tp2 of the next winding S1 to the leakage transformer T2
From the tap Tp2 of the primary winding P5 and the tap Tp1 of the primary winding P5 through the resonance capacitor C1 to the transformer T1.
The secondary current I21 flows through the tap Tp1 of the secondary winding S1.

As a result, magnetic energy is induced in the secondary winding S6 of the leakage transformer T2, so that a current flows from the tap Tp2 of the secondary winding S6 to the diode D2 and is rectified and smoothed by the capacitor C3 to be secondary side. The output voltage is output to.

At the same time, in the DC-DC converter 10,
The leakage inductance Lo of the leakage transformer T2 and the series resonance by the resonance capacitor C1 cause a sinusoidal drain current Id1 as shown in FIG.
Waveform appears in the switching element Q1.

Next, 2 is applied to the-input terminal of the operational amplifier OP1.
Since the output voltage on the secondary side is input, the error voltage is output from the operational amplifier OP1 to the VCO, and further, the gate drive signal Vg2 having a phase substantially opposite to the gate drive signal Vg1 is output from the VCO to the gate of the switching element Q2. It

Here, at the timing t3, the drain-source voltage Vds2 of the switching element Q2 becomes 0V. At this time, the gate drive signal Vg2 is supplied to the switching element Q2, and the switching element Q2 is turned on. Accordingly, the drain current Id from the DC power source E
2 is the center tap Tpc of the primary winding of the transformer T1,
From the tap Tp2 of the primary winding P2 to the switching element Q2
To the GND via the drain-source of.

At this time, magnetic energy is induced in the secondary winding S1 of the transformer T1.
From the tap Tp1 of the secondary winding S1 through the resonance capacitor C1, the tap Tp1 of the primary winding P5 of the leakage transformer T2, the tap Tp2 of the primary winding P5 to the transformer T1.
The secondary current I22 flows through the tap Tp2 of the secondary winding S1.

As a result, magnetic energy is induced in the secondary winding S5 of the leakage transformer T2. Therefore, when a current flows from the tap Tp1 of the secondary winding S5 to the diode D1, the capacitor C3 rectifies and smoothes the secondary winding. The output voltage is output to the side. By repeating the above-mentioned operation, the output voltage on the secondary side is increased and then stabilized.

The effect of the first embodiment is that the direct current supplied from the direct current power source E is converted by the direct current-alternating current conversion circuit 15 into an alternating current having a small current and a high voltage.
A small current / high voltage AC from the AC conversion circuit 15 is input to the primary winding of the leakage transformer T2 via the resonance capacitor C1 to induce AC in the secondary winding, and the secondary winding of the leakage transformer T2. The AC from the line is rectified and smoothed by the output circuit 13 to output a DC voltage, and the control circuit 11 generates a gate drive signal for controlling the DC-AC conversion circuit 15 according to the DC voltage from the output circuit 13. Therefore, even when a low-voltage DC power supply is used, a small current / high-voltage AC can be made to flow through the resonance capacitor C1.
It is possible to provide a resonance type DC-DC converter capable of supplying a large amount of power to the load side even if the DC power supply has a low voltage.

Further, as shown in FIG. 1, the DC / AC converting circuit 15 connects the tap Tp1 of the primary winding P1 of the transformer T1 in series with the switching element Q1 and connects it in series with the switching element Q2. Is connected to the tap Tp2 of the primary winding P2 of the transformer T1, the center tap Tpc of the primary winding of the transformer T1 is connected to the DC power source E, the tap Tp1 of the secondary winding S1 of the transformer T1 and the leakage transformer T2. Is connected to the tap Tp1 of the primary winding P5 of the transformer via the resonance capacitor C1, and the secondary winding S of the transformer T1 is connected.
The first tap Tp2 and the tap Tp2 of the primary winding P5 of the leakage transformer T2 are connected to each other.

Therefore, the AC voltage output from the secondary winding S1 of the transformer T1 is resonated by the leakage inductance of the leakage transformer T2 and the resonance capacitor C1 and input to the primary winding P5 of the leakage transformer T2. , The secondary winding S5 of the leakage transformer T2,
An AC voltage can be induced in S6, the AC voltage from the secondary winding of the leakage transformer T2 can be rectified and smoothed by the output circuit 13, and the DC voltage Vo can be output.

As a result, even when a low-voltage DC power supply is used, a small current / high-voltage AC can be made to flow through the resonance capacitor C1, and large power can be supplied to the load side even if the DC power supply has a low voltage. It is possible to provide a resonance type DC-DC converter capable of performing.

Further, since the transformer conversion efficiency of 99% or more can be expected by using the transformer T1 whose leakage is reduced as much as possible, even when a low-voltage DC power source is used, the resonance type DC- A DC converter can be provided.

(Modification 1) FIG. 3 is a diagram showing a modification of the resonance type DC-DC converter 20 according to the first embodiment of the present invention. The characteristic of the resonance type DC-DC converter 20 shown in FIG. 3 is that capacitors C5 and C6 for voltage quasi-resonance are added in parallel between the drains and sources of the switching elements Q1 and Q2 formed of field effect transistors. .

When the switching element Q1 is off, the inductance of the primary winding P5 of the leakage transformer T2 converted to the primary side by the primary-secondary winding ratio of the transformer T1 and the drain of the switching element Q1.
Resonance is caused by the capacitor C5 connected in parallel between the sources and the capacitor C6 connected in parallel between the drain and the source of the switching element Q2.

When the switching element Q2 is off,
An inductance obtained by converting the inductance of the primary winding P5 of the leakage transformer T2 into the primary side by the primary-secondary winding ratio of the transformer T1, and a capacitor C5 connected in parallel between the drain and source of the switching element Q2. Resonance is caused by the capacitor C6 connected in parallel between the drain and source of the switching element Q1. in this way,
Voltage resonance can be generated by causing the leakage inductance of the transformer T1 and the capacitors C5 and C6 to resonate.

(Modification 2) FIG. 4 is a view showing a modification of the resonance type DC-DC converter 30 according to the first embodiment of the present invention. The resonant DC-DC converter 30 shown in FIG. 4 is characterized in that a leakage-less transformer T20 which is a non-leakage transformer is used in place of the leakage transformer T2 shown in FIG. Tap Tp2 of winding S1 and transformer T
It is inserted between the 20 primary winding P5 and the tap Tp2 to form a resonance circuit between the resonance capacitor C1 and the inductance L1.

Resonant DC-DC converter 1 shown in FIG.
In the circuit configuration of 0, the resonance circuit is configured by using the leakage inductance of the leakage transformer T2.
It was difficult to predict the inductance of this leak.

Therefore, in this modified example, the transformer T20 is used, the inductance L1 is externally inserted, and the resonance circuit is configured between the resonance capacitor C1 and the inductance L1 to easily design the resonance circuit. can do.

(Second Embodiment) FIG. 5 shows a resonance type DC-DC converter 40 according to a second embodiment of the present invention.
It is a figure which shows the detailed structure of. Hereinafter, only the characteristic configuration of the resonance type DC-DC converter 40 will be described with reference to the circuit diagram shown in FIG. 5, and the description of the same configuration as the configuration described in the first embodiment will be omitted. To do.

The DC-AC conversion circuit 45 includes a DC power source E.
In order to convert the DC voltage supplied from the AC into a small current / high voltage AC, switching elements Q1, Q2, transformer T1
Is provided, and as shown in FIG. 5, only the primary windings P1 and P2 of the transformer T1 are used as they are.

The DC power source E is the primary winding P of the transformer T1.
1 and P2 are connected to the center tap Tpc, and the drain of the switching element Q1 and one end of the resonance capacitor C1 are connected to the tap Tp1 of the primary winding P1. The source of this element Q1 is the DC power source E. It is connected to the GND side. The tap Tp2 of the primary winding P2 has a drain of the switching element Q2 and a leakage transformer T2.
The tap Tp2 is connected, and the source of the element Q2 is connected to the GND side of the DC power supply E.

Tap Tp of the primary winding P1 of the transformer T1
1 is connected to the tap Tp1 of the primary winding P5 of the leakage transformer T2 via the resonance capacitor C1, and the tap Tp2 of the primary winding P2 of the transformer T1 and the primary winding P5 of the leakage transformer T2 are connected. The tap Tp2 is directly connected.

Also in this embodiment, the DC voltage E is treated as a power source capable of extracting a low voltage and a large current, and the primary winding of the transformer T1 and the primary winding P5 of the leakage transformer T2 have a high voltage and a small voltage. It is assumed that a current appears and that a low voltage / large current can be taken out from the secondary windings S5 and S6 of the leakage transformer T2.

Next, the operation of the resonance type DC-DC converter 40 will be described with reference to the timing chart shown in FIG. First, when the DC power source E is turned on to the DC-DC converter 40, since the-input terminal of the operational amplifier OP1 provided in the control circuit 11 is 0 V, the operational amplifier OP1 outputs the maximum level error voltage to the VCO,
Further, if the gate drive signal Vg1 as shown in FIG.
It is output from O to the gate of the switching element Q1.

At timing t1, the drain-source voltage Vds1 of the switching element Q1 becomes 0V. At this time, the gate drive signal V is applied to the switching element Q1.
The switching element Q1 is turned on by supplying g1.
As a result, the drain current Id1 from the DC power source E flows from the center tap Tpc of the primary winding of the transformer T1 and the tap Tp1 of the primary winding P1 to the GND via the drain-source of the switching element Q1.

At this time, from the DC power source E to the center taps Tpc to Tp2 of the primary winding of the transformer T1, the taps Tp2 and 1 of the primary winding P5 of the leakage transformer T2.
Tap Tp1 of the secondary winding P5, tap Tp of the primary winding P5
The secondary current I21 flows from 1 to the resonance capacitor C1 and the tap Tp1 of the primary winding P1 of the transformer T1.

As a result, since magnetic energy is induced in the secondary winding S6 of the leakage transformer T2, a current flows from the tap Tp2 of the secondary winding S6 to the diode D2 and is rectified and smoothed by the capacitor C3 to be secondary. The output voltage is output to the side.

At the same time, in the DC-DC converter 40,
The leakage inductance Lo of the leakage transformer T2 and the series resonance by the resonance capacitor C1 cause a sinusoidal drain current Id1 as shown in FIG.
Waveform appears in the switching element Q1.

Next, 2 is applied to the-input terminal of the operational amplifier OP1.
Since the output voltage on the secondary side is input, the error voltage is output from the operational amplifier OP1 to the VCO, and further, the gate drive signal Vg2 having a phase substantially opposite to the gate drive signal Vg1 is output from the VCO to the gate of the switching element Q2. It

Here, at the timing t3, the drain-source voltage Vds2 of the switching element Q2 becomes 0V. At this time, the gate drive signal Vg2 is supplied to the switching element Q2, and the switching element Q2 is turned on. Accordingly, the drain current Id from the DC power source E
2 is the center tap Tpc of the primary winding of the transformer T1,
From the tap Tp2 of the primary winding P2 to the switching element Q2
To the GND via the drain-source of.

At this time, from the DC power source E to the center tap Tpc of the primary winding of the transformer T1 to the tap Tp1, and to the leakage transformer 1 through the resonance capacitor C1.
Tap Tp1 of the secondary winding P5, tap Tp of the primary winding P5
2 from 2 to tap Tp2 of primary winding P1 of transformer T1
The next current I22 flows.

As a result, since magnetic energy is induced in the secondary winding S5 of the leakage transformer T2, a current flows from the tap Tp1 of the secondary winding S6 to the diode D1 and is rectified and smoothed by the capacitor C3 to be secondary side. The output voltage is output to.

By repeating the above operation, the output voltage on the secondary side rises and then stabilizes. The effect in the second embodiment is that the direct current supplied from the direct current power source E is converted by the direct current-alternating current conversion circuit 45 into an alternating current having a small current 1/2 times and a high voltage twice as high as the direct current. An alternating current of 1/2 times small current and 2 times high voltage from the AC conversion circuit 45 is input to the primary winding of the leakage transformer T2 via the resonance capacitor C1 to induce the alternating current in the secondary winding. ,
To rectify and smooth the AC from the secondary winding of the leakage transformer T2 by the output circuit 13 to output a DC voltage, and to control the DC-AC conversion circuit 45 in the control circuit 11 according to the DC voltage from the output circuit 13. Since the gate drive signal of is generated, even if a low-voltage DC power supply is used, it is possible to pass a 1 / 2-fold small current and a 2-fold high-voltage AC through the resonance capacitor C1. Resonant type DC-DC capable of supplying a large amount of power to the load side even at low voltage
A converter can be provided.

Further, as shown in FIG. 5, the DC-AC converting circuit 45 connects the tap Tp1 of the winding of the transformer T1 in series with the switching element Q1, and the transformer T1 in series with the switching element Q2. Winding tap T
p2 is connected to the DC power source E, the center tap Tpc of the winding of the transformer T1 is connected, and the tap Tp1 of the winding of the transformer T1 and the tap T of the primary winding of the leakage transformer T2 are connected.
p1 is connected via a resonance capacitor C1, and the winding tap Tp2 of the transformer T1 and the leakage transformer T2 are connected.
It is configured to be connected to the tap Tp2 of the primary winding.

Therefore, the AC voltage output from the winding of the transformer T1 is resonated by the leakage inductance of the leakage transformer T2 and the resonance capacitor C1 and input to the primary winding of the leakage transformer T2.
An AC voltage can be induced in the secondary windings S5 and S6 of the leakage transformer T2, and the AC voltage from the secondary winding of the leakage transformer T2 can be rectified and smoothed by the output circuit 13 to output the DC voltage Vo.

As a result, even when a low-voltage DC power supply is used, the resonance capacitor C1 has a small current of 1/2 and
Resonant type D that can supply double high voltage AC and can supply large power to load side even if DC power supply has low voltage
A C-DC converter can be provided.

Further, since the transformer conversion efficiency of 99% or more can be expected by using the transformer T1 whose leakage is reduced as much as possible, even when a low-voltage DC power source is used, the resonance type DC- A DC converter can be provided.

(Modification 3) A modification of the resonance type DC-DC converter 40 according to the second embodiment of the present invention will be described. The feature of this modification 2 is that the modification 1 shown in FIG.
Similarly, capacitors C5 and C6 for voltage quasi-resonance may be added in parallel between the drain and source of each of the switching elements Q1 and Q2 that are field effect transistors.

When the switching element Q1 is off, the inductance of the primary winding P5 of the leakage transformer T2 is converted to the primary side by the primary-secondary winding ratio of the transformer T1 and the drain of the switching element Q1.
Resonance is caused by the capacitor C5 connected in parallel between the sources and the capacitor C6 connected in parallel between the drain and the source of the switching element Q2.

When the switching element Q2 is off,
An inductance obtained by converting the inductance of the primary winding P5 of the leakage transformer T2 into the primary side by the primary-secondary winding ratio of the transformer T1, and a capacitor C5 connected in parallel between the drain and source of the switching element Q2. Resonance is caused by the capacitor C6 connected in parallel between the drain and source of the switching element Q1. in this way,
Voltage resonance can be generated by causing the leakage inductance of the transformer T1 and the capacitors C5 and C6 to resonate.

(Modification 4) A modification of the resonance type DC-DC converter 40 according to the second embodiment of the present invention will be described. The feature of the modification 4 is that the modification 2 shown in FIG.
5, a leakage transformer T20 which is a non-leakage transformer is used in place of the leakage transformer T2 shown in FIG. 5, and the tap Tp2 of the secondary winding S1 of the transformer T1 and the primary winding of the transformer T20 are externally attached. An inductance L1 is inserted between the tap Tp2 of P5 and a resonance circuit between the resonance capacitor C1 and the inductance L1.

Resonant DC-DC converter 4 shown in FIG.
In the circuit configuration of 0, the resonance circuit is configured by using the leakage inductance of the leakage transformer T2.
It was difficult to predict the inductance of this leak.

Therefore, in the present modification, the transformer T20 is used, the inductance L1 is externally inserted, and the resonance circuit is configured between the resonance capacitor C1 and the inductance L1 to easily design the resonance circuit. can do.

(Third Embodiment) FIG. 6 shows a resonance type DC-DC converter 50 according to a third embodiment of the present invention.
It is a figure which shows the detailed structure of. Hereinafter, only the characteristic configuration of the resonance type DC-DC converter 50 will be described with reference to the circuit diagram shown in FIG. 6, and the description of the same configuration as the configuration described in the first embodiment will be omitted. To do.

The DC-AC conversion circuit 55 has a DC power source E.
Switching elements Q1 and Q2 and an autotransformer T3 are provided to convert the DC voltage supplied from the AC into a small current / high voltage AC. As shown in FIG. 6, the primary winding P1 of the autotransformer T3 is provided. , P2 are continuously wound around non-insulated winding P3 to improve magnetic coupling.

The DC power source E is connected to the center taps Tpc of the primary windings P1 and P2 of the autotransformer T3 and to the tap Tp2 of the primary winding P5 of the leakage transformer T2. Further, in the tap Tp1 of the primary winding P1,
The drain of the switching element Q1 and the tap Tp4 of the winding P3 are connected, and the source of this element Q1 is the DC power source E.
Is connected to the GND side of. Further, the drain of the switching element Q2 is connected to the tap Tp2 of the primary winding P2, and the source of this element Q2 is the GND of the DC power source E.
Connected to the side. The tap Tp3 of the winding P3 of the auto transformer T3 is connected to the tap Tp1 of the primary winding P5 of the leakage transformer T2 via the resonance capacitor C1.

Also in this embodiment, the DC voltage E is treated as a power source capable of taking out a low voltage and a large current, and a high voltage is applied to the primary winding of the autotransformer T3 and the primary winding P5 of the leakage transformer T2. It is assumed that a small current appears and that a low voltage / large current can be taken out from the secondary windings S5 and S6 of the leakage transformer T2.

Next, the operation of the resonance type DC-DC converter 50 will be described with reference to the timing chart shown in FIG. First, when the DC power supply E is turned on to the DC-DC converter 50, since the-input terminal of the operational amplifier OP1 provided in the control circuit 11 is 0V, the operational amplifier OP1 outputs the maximum level error voltage to the VCO,
Further, if the gate drive signal Vg1 as shown in FIG.
It is output from O to the gate of the switching element Q1. At timing t1, the drain-source voltage Vds1 of the switching element Q1 becomes 0V. At this time, the gate drive signal Vg1 is supplied to the switching element Q1,
The switching element Q1 is turned on. As a result, the drain current Id1 from the DC power source E is changed to
Flows from the center tap Tpc of the primary winding to the GND from the tap Tp1 of the primary winding P1 via the drain-source of the switching element Q1.

At this time, from the DC power source E to the center tap Tpc of the primary winding of the auto transformer T3 to the tap Tp2 of the primary winding P5 of the leakage transformer T2, and the primary winding P.
The secondary current I21 flows from the tap Tp1 of No. 5, the tap Tp1 of the primary winding P5 to the resonance capacitor C1, and from the tap Tp3 of the winding P3 of the autotransformer T3 to the tap Tp4.

As a result, since magnetic energy is induced in the secondary winding S6 of the leakage transformer T2, a current flows from the tap Tp2 of the secondary winding S6 to the diode D2 and is rectified and smoothed by the capacitor C3 to be secondary. The output voltage is output to the side.

At the same time, in the DC-DC converter 40,
The leakage inductance Lo of the leakage transformer T2 and the series resonance by the resonance capacitor C1 cause a sinusoidal drain current Id1 as shown in FIG.
Waveform appears in the switching element Q1.

Next, 2 is applied to the-input terminal of the operational amplifier OP1.
Since the output voltage on the secondary side is input, the error voltage is output from the operational amplifier OP1 to the VCO, and further, the gate drive signal Vg2 having a phase substantially opposite to the gate drive signal Vg1 is output from the VCO to the gate of the switching element Q2. It

At the timing t3, the drain-source voltage Vds2 of the switching element Q2 becomes 0V. At this time, the gate drive signal Vg2 is supplied to the switching element Q2, and the switching element Q2 is turned on. Accordingly, the drain current Id from the DC power source E
2 is the center tap T of the primary winding of the autotransformer T3
pc from the tap Tp2 of the primary winding P2 to the GND via the drain-source of the switching element Q2.

At this time, from the DC power source E to the center tap Tpc of the primary winding of the autotransformer T3 to the tap Tp.
1, taps Tp4 to Tp3 of the winding P3 of the autotransformer T3, taps Tp1 and P5 of the primary winding P5 of the leakage transformer T2 via the resonance capacitor C1
The secondary current I22 flows from the tap Tp2 of the above to the center tap Tpc of the primary winding of the autotransformer T3.

As a result, since magnetic energy is induced in the secondary winding S5 of the leakage transformer T2, a current flows from the tap Tp1 of the secondary winding S6 to the diode D1 and is rectified and smoothed by the capacitor C3 to be secondary side. The output voltage is output to. By repeating the above operation, 2
It is stabilized after the output voltage on the secondary side has risen.

The effect of the third embodiment is that the direct current supplied from the direct current power source E is converted by the direct current-alternating current conversion circuit 55 into a small current / high voltage determined by an arbitrary winding ratio of P1 = P2: P3 from this direct current. The alternating current is converted into alternating current, and the alternating current of small current and high voltage from the direct current-alternating current conversion circuit 55 is used as the resonance capacitor C.
1 is input to the primary winding of the leakage transformer T2 to induce an alternating current in the secondary winding, and the leakage transformer T2
AC from the secondary winding of the output circuit 13 is rectified and smoothed by the output circuit 13 to output a DC voltage.
Since a gate drive signal for controlling the DC-AC conversion circuit 55 is generated according to the DC voltage from the circuit 3, even when the low-voltage DC power source E is used, a small current / high voltage is applied to the resonance capacitor C1. The alternating current of
It is possible to provide a resonance type DC-DC converter capable of supplying a large amount of electric power to the load side even when the voltage is low.

Further, as shown in FIG. 6, the DC / AC conversion circuit 55 has a tap Tp1 and a winding P1 of the primary winding P1 of the autotransformer T3 connected in series with the switching element Q1.
3 is connected to the tap Tp4 of the autotransformer Q2, the tap Tp2 of the primary winding P2 of the autotransformer T3 is connected in series to the switching element Q2, and the center tap Tpc of the primary winding of the autotransformer T3 is connected to the DC power source E. And the tap Tp3 of the winding P3 of the autotransformer T3 and the tap Tp1 of the primary winding P5 of the leakage transformer T2 are connected via the resonance capacitor C1, and the center tap Tpc of the primary winding of the autotransformer T3 is connected. And the tap Tp2 of the primary winding of the leakage transformer T2 are connected.

Therefore, the AC voltage output from the winding of the autotransformer T3 is resonated by the leakage inductance of the leakage transformer T2 and the resonance capacitor C1 and input to the primary winding of the leakage transformer T2. An AC voltage can be induced in the secondary windings S5 and S6 of T2, and the AC voltage from the secondary winding of the leakage transformer T2 can be rectified and smoothed by the output circuit 13 to output the DC voltage Vo.

As a result, even when a low-voltage DC power supply is used, a small current / high-voltage AC can be made to flow through the resonance capacitor C1, and large power can be supplied to the load side even if the DC power supply has a low voltage. It is possible to provide a resonance type DC-DC converter capable of performing.

(Modification 5) Since the modification of the resonance type DC-DC converter 50 according to the third embodiment of the present invention is the same as the modification 2 described above, its explanation is omitted.

(Modification 6) A modification of the resonance type DC-DC converter 50 according to the third embodiment of the present invention will be described. This modified example 6 is characterized in that modified example 2 shown in FIG.
6, a leakage transformer T20 which is a non-leakage transformer is used in place of the leakage transformer T2 shown in FIG. 6, and the center tap Tpc of the primary winding P2 of the autotransformer T3 and the primary of the transformer T20 are externally attached. An inductance L1 is inserted between the winding P5 and the tap Tp2 to form a resonance circuit between the resonance capacitor C1 and the inductance L1.

Resonant DC-DC converter 5 shown in FIG.
In the circuit configuration of 0, the resonance circuit is configured by using the leakage inductance of the leakage transformer T2.
It was difficult to predict the inductance of this leak.

Therefore, in this modification, the transformer T20 is used, the inductance L1 is externally inserted, and the resonance circuit is configured between the resonance capacitor C1 and the inductance L1 to easily design the resonance circuit. can do.

(Fourth Embodiment) FIG. 7 shows a resonance type DC-DC converter 60 according to a fourth embodiment of the present invention.
It is a figure which shows the detailed structure of. Hereinafter, only the characteristic configuration of the resonance type DC-DC converter 60 will be described with reference to the circuit diagram shown in FIG. 7, and the description of the same configuration as the configuration described in the first embodiment will be omitted. To do.

The DC-AC conversion circuit 65 includes a DC power source E.
In order to convert the DC voltage supplied from the AC into a small current / high voltage AC, switching elements Q1 and Q2 and an autotransformer T5 are provided. As shown in FIG. 7, the primary winding P1 of the autotransformer T5 is provided. , P2 are continuously wound around non-insulated primary windings P3, P4 to further improve magnetic coupling.

The DC power source E includes a tap Tp1 of the primary winding P1 and a tap Tp of the primary winding P4 of the autotransformer T5.
4 is connected to the connection. In addition, the primary windings P3 and P4
The drain of the switching element Q1 is connected to the center tap Tpc of the DC power source E.
Is connected to the GND side of. Further, the primary winding P1,
A switching element Q2 is provided at the center tap Tpc of P2.
Of the DC power source E is connected to the GND side.

The tap Tp3 of the primary winding P3 of the auto transformer T5 is connected to the tap Tp1 of the primary winding P5 of the leakage transformer T2 via the resonance capacitor C1. The tap Tp2 of the primary winding P2 of the auto transformer T5 is the primary winding P5 of the leakage transformer T2.
Is connected to the tap Tp2.

Also in this embodiment, the DC voltage E is treated as a power source capable of taking out a low voltage and a large current, and a high voltage is applied to the primary winding of the autotransformer T5 and the primary winding P5 of the leakage transformer T2. It is assumed that a small current appears and that a low voltage / large current can be taken out from the secondary windings S5 and S6 of the leakage transformer T2.

Next, the operation of the resonance type DC-DC converter 60 will be described with reference to the timing chart shown in FIG. First, when the DC power supply E is turned on to the DC-DC converter 50, since the-input terminal of the operational amplifier OP1 provided in the control circuit 11 is 0V, the operational amplifier OP1 outputs the maximum level error voltage to the VCO,
Further, if the gate drive signal Vg1 as shown in FIG.
It is output from O to the gate of the switching element Q1.

At timing t1, the drain-source voltage Vds1 of the switching element Q1 becomes 0V. At this time, the gate drive signal V is applied to the switching element Q1.
The switching element Q1 is turned on by supplying g1.
As a result, the drain current Id1 from the DC power source E flows from the tap Tp4 of the primary winding P4 of the autotransformer T5 to the switching element Q from the center tap Tpc of the primary winding P4.
1 through drain-source to GND.

At this time, from the DC power source E to the tap Tp1 of the primary winding P1 of the autotransformer T5 to the primary winding Tp.
2. Tap T of the primary winding P5 of the leakage transformer T2
p2, the tap Tp1 of the primary winding P5, the tap Tp1 of the primary winding P5 to the resonance capacitor C1, the tap Tp3 of the winding P3 of the autotransformer T5 to the center tap Tpc.
A secondary current I21 flows through the.

As a result, since magnetic energy is induced in the secondary winding S6 of the leakage transformer T2, a current flows from the tap Tp2 of the secondary winding S6 to the diode D2 and is rectified and smoothed by the capacitor C3 to be secondary. The output voltage is output to the side.

At the same time, in the DC-DC converter 60,
The leakage inductance Lo of the leakage transformer T2 and the series resonance by the resonance capacitor C1 cause a sinusoidal drain current Id1 as shown in FIG.
Waveform appears in the switching element Q1.

Next, 2 is applied to the-input terminal of the operational amplifier OP1.
Since the output voltage on the secondary side is input, the error voltage is output from the operational amplifier OP1 to the VCO, and further, the gate drive signal Vg2 having a phase substantially opposite to the gate drive signal Vg1 is output from the VCO to the gate of the switching element Q2. It

Here, at the timing t3, the drain-source voltage Vds2 of the switching element Q2 becomes 0V. At this time, the gate drive signal Vg2 is supplied to the switching element Q2, and the switching element Q2 is turned on. Accordingly, the drain current Id from the DC power source E
2 is the drain of the switching element Q2 from the center tap Tpc of the primary windings P1 and P2 of the autotransformer T5.
It flows to GND through the source.

At this time, from the DC power source E to the tap Tp4 of the primary winding P4 of the autotransformer T5 and the autotransformer T5.
5, tap Tp3 of primary winding P3, resonance capacitor C
1 through the tap Tp1 of the primary winding P5 of the leakage transformer T2 to the tap Tp2 of the primary winding P2 of the autotransformer T5 from the tap Tp2 of the primary winding P5.
22 flows.

As a result, since magnetic energy is induced in the secondary winding S5 of the leakage transformer T2, a current flows from the tap Tp1 of the secondary winding S6 to the diode D1 and is rectified and smoothed by the capacitor C3 to be secondary side. The output voltage is output to.

By repeating the above-described operation, the output voltage on the secondary side is increased and then stabilized.

The effect of the fourth embodiment is that the direct current supplied from the direct current power source E is converted by the direct current-alternating current conversion circuit 65 into an alternating current of a small current and a high voltage.
A small current / high voltage AC from the AC conversion circuit 65 is input to the primary winding of the leakage transformer T2 via the resonance capacitor C1 to induce an AC in the secondary winding, and the secondary winding of the leakage transformer T2. The output circuit 13 rectifies and smoothes the AC from the line to output a DC voltage, and the control circuit 11 generates a gate drive signal for controlling the DC-AC conversion circuit 65 according to the DC voltage from the output circuit 13. Therefore, even when the low-voltage DC power supply E is used, a small current / high-voltage AC can be made to flow through the resonance capacitor C1, and large power can be supplied to the load side even if the DC power supply E is at a low voltage. It is possible to provide a resonance type DC-DC converter capable of performing the above.

As shown in FIG. 7, the DC / AC conversion circuit 65 includes a center tap T of the primary windings P3 and P4 of the autotransformer T5 in series with the switching element Q1.
pc, the center tap Tpc of the primary windings P1 and P2 of the autotransformer T5 are connected in series to the switching element Q2, and the DC power source E is connected to the center of the autotransformer T5.
Tap Tp1 of the secondary winding P1 and tap Tp of the primary winding P4
4 and the tap Tp3 of the primary winding P3 of the autotransformer T5 and the tap Tp1 of the primary winding P5 of the leakage transformer T2 are connected via the resonance capacitor C1. Tap Tp2 on line P2
And the tap Tp of the primary winding P5 of the leakage transformer T2
It is configured so as to be connected to 2.

Therefore, the AC voltage output from the primary winding of the autotransformer T5 is resonated by the leakage inductance of the leakage transformer T2 and the resonance capacitor C1 and input to the primary winding of the leakage transformer T2. Secondary windings S5, S of the leakage transformer T2
AC voltage is induced in 6 and 2 of leakage transformer T2
The AC voltage from the next winding can be rectified and smoothed by the output circuit 13 to output the DC voltage Vo.

As a result, even when a low-voltage DC power supply is used, a small current / high-voltage AC can be made to flow through the resonance capacitor C1, and large power can be supplied to the load side even if the DC power supply has a low voltage. It is possible to provide a resonance type DC-DC converter capable of performing.

(Modification 7) A modification of the resonance type DC-DC converter 60 according to the fourth embodiment of the present invention is also the same as the modification 2 described above, and the description thereof will be omitted.

(Modification 8) A modification of the resonance type DC-DC converter 60 according to the fourth embodiment of the present invention will be described. The feature of this modification 8 is that the modification 2 shown in FIG.
Similarly to the leakage transformer T2 shown in FIG. 7, a leakage-free transformer T20 that is a non-leakage transformer is used, and the center tap Tpc of the primary winding P2 of the autotransformer T3 and the primary of the transformer T20 are externally attached. An inductance L1 is inserted between the winding P5 and the tap Tp2 to form a resonance circuit between the resonance capacitor C1 and the inductance L1.

Resonant DC-DC converter 6 shown in FIG.
In the circuit configuration of 0, the resonance circuit is configured by using the leakage inductance of the leakage transformer T2.
It was difficult to predict the inductance of this leak.

Therefore, in the present modification, the transformer T20 is used, the inductance L1 is externally inserted, and the resonance circuit is configured between the resonance capacitor C1 and the inductance L1 to easily design the resonance circuit. can do.

According to the first to fourth embodiments, the resonance type DC- which has excellent efficiency even in the low voltage power supply circuit.
It becomes possible to employ a DC converter. As a result, efficiency is improved, heat dissipation is simplified, noise is reduced, and noise countermeasure parts can be significantly reduced.
The cost of the C-DC converter can be kept low.

[0117]

As described above, according to the present invention,
The direct current supplied from the direct current power supply is converted by this direct current to alternating current into a small current and high voltage alternating current from this direct current.
A small current / high voltage AC from the AC conversion circuit is input to the primary winding of the leakage transformer via the resonance capacitor to induce AC in the secondary winding, and the leakage transformer's 2
Since the alternating current from the next winding is rectified and smoothed by the output circuit to output the direct current voltage, the control circuit generates the gate drive signal for controlling the direct current-alternating current conversion circuit according to the direct current voltage from the output circuit. Resonant DC that can supply a small current and high voltage AC to the resonance capacitor even when a low-voltage DC power supply is used, and can supply a large amount of power to the load side even if the DC power supply has a low voltage. -A DC converter can be provided.

As a result, it becomes possible to employ a resonance type DC-DC converter having excellent efficiency even in a low voltage power supply circuit. For this reason, efficiency is improved, heat dissipation is simplified, and noise is reduced, so that it is possible to greatly reduce the number of noise countermeasure components, and it is possible to keep the cost of the DC-DC converter low.

[Brief description of drawings]

FIG. 1 is a resonance type DC- according to a first embodiment of the present invention.
It is a figure which shows the detailed structure of the DC converter 10.

FIG. 2 is a timing chart for explaining the operation of the resonance type DC-DC converter.

FIG. 3 is a resonance type DC- according to the first embodiment of the present invention.
It is a figure which shows the modification of the DC converter 20.

FIG. 4 is a resonance type DC- according to the first embodiment of the present invention.
It is a figure which shows the modification of the DC converter 30.

FIG. 5 is a resonance type DC- according to a second embodiment of the present invention.
It is a figure which shows the detailed structure of the DC converter 40.

FIG. 6 is a resonance type DC- according to a third embodiment of the present invention.
It is a figure which shows the detailed structure of the DC converter 50.

FIG. 7 is a resonance type DC- according to a fourth embodiment of the present invention.
It is a figure which shows the detailed structure of the DC converter 60.

FIG. 8 is a diagram showing a detailed configuration of a conventional half-bridge type resonant DC-DC converter.

FIG. 9 is a timing chart for explaining the operation of a conventional half-bridge type resonance DC-DC converter.

[Explanation of symbols]

C1 resonance capacitor E DC power supply Q1, Q2 switching element T2 leakage transformer 11 Control circuit 13 Output circuit 15, 45, 55, 65 DC-AC conversion circuit

Claims (10)

[Claims] 1. A direct current-alternating current conversion circuit for converting direct current supplied from a direct current power source into alternating current of lower current / high voltage than this direct current, and small current / high voltage alternating current from the direct current-alternating current conversion circuit for resonance. A leakage transformer that inputs to the primary winding via a capacitor to induce an alternating current in the secondary winding, an output circuit that rectifies and smoothes the alternating current from the secondary winding of the leakage transformer, and outputs a DC voltage, and an output A resonance type DC-DC converter, comprising: a control circuit that generates a control signal for controlling the DC-AC conversion circuit according to a DC voltage from the circuit. 2. The DC-AC conversion circuit includes first and second switching elements that are turned on / off alternately according to a control signal from the control circuit, a first tap, a center tap, and a second tap. Primary winding with taps and 2 with first and second taps
A primary winding of the transformer in series with the first switching element, the transformer having a secondary winding, and a transformer for boosting an AC voltage input to the primary winding to induce the secondary winding. A first tap of a wire is connected, a second tap of the primary winding of the transformer is connected in series to the second switching element, and a center of the primary winding of the transformer is connected to the DC power source. A tap is connected, the first tap of the secondary winding of the transformer and the first tap of the primary winding of the leakage transformer are connected via a resonance capacitor, and the secondary winding of the transformer is connected. The second tap is connected to the second tap of the primary winding of the leakage transformer, and the AC voltage output from the secondary winding of the transformer is resonated by the leakage inductance of the leakage transformer and the resonance capacitor. hand Resonant DC-D, characterized in that input to the primary winding of the serial leakage transformer
C converter. 3. The DC-AC conversion circuit includes first and second switching elements that are turned on / off alternately according to a control signal from the control circuit, a first tap, a center tap, and a second tap. A winding provided with a tap, the first tap of the winding is connected in series to the first switching element, and the second tap of the winding is connected in series to the second switching element. The center tap of the winding is connected to the DC power supply, and the first tap of the winding and the first tap of the primary winding of the leakage transformer are connected via a resonance capacitor. The second tap of the winding is connected to the second tap of the primary winding of the leakage transformer, and the AC voltage output from the winding is connected to the leakage inductance of the leakage transformer and the resonance coil. Resonant DC-D according to claim 1, wherein by resonating the capacitor, wherein the input to the primary winding of said leakage transformer
C converter. 4. The DC-AC conversion circuit includes first and second switching elements that are turned on / off alternately according to a control signal from the control circuit, a first tap, a center tap, and a second tap. A first winding having a tap, a third winding and a fourth tap, and an autotransformer having a second winding continuously wound with the first winding, The first tap of the first winding of the autotransformer and the fourth tap of the second winding of the autotransformer are connected in series to the first switching element, and are connected in series to the second switching element. The second tap of the first winding of the autotransformer is connected, the center tap of the first winding of the autotransformer is connected to the DC power supply, and the third tap of the second winding of the autotransformer is connected. Tap and the primary winding of the leakage transformer No. 1 tap is connected via a resonance capacitor, the center tap of the first winding of the autotransformer is connected to the second tap of the primary winding of the leakage transformer, and the first tap of the autotransformer is connected. 2. The resonance type DC- according to claim 1, wherein the AC voltage output from the second winding is resonated by the leakage inductance of the leakage transformer and the resonance capacitor and input to the primary winding of the leakage transformer. DC converter. 5. The DC-AC conversion circuit includes first and second switching elements that are alternately turned on / off in response to a control signal from the control circuit, a first tap, a center tap, and a second tap. A first winding having a tap, a third tap, a center tap, and an autotransformer having a fourth tap and a second winding continuous with the first winding. Connecting the center tap of the first winding of the autotransformer in series with the first switching element, and connecting the center tap of the second winding of the autotransformer in series with the second switching element. A tap is connected to the DC power source, a first tap of the first winding of the autotransformer is connected to a fourth tap of the second winding of the autotransformer, and a second tap of the second winding of the autotransformer is connected. 3 taps and the leakage tiger Of the primary winding of the leakage transformer and the first tap of the primary winding of the leakage transformer are connected via a resonance capacitor, and the second tap of the first winding of the autotransformer and the second tap of the primary winding of the leakage transformer are connected. And resonating the AC voltage output from the first and second windings of the autotransformer with the leakage inductance of the leakage transformer and a resonance capacitor, and inputting the AC voltage to the primary winding of the leakage transformer. The resonance type DC-DC converter according to claim 1. 6. The first and second switching elements are field effect transistors, and have second and third capacitors connected between a drain terminal and a source terminal, respectively. The resonant DC-DC converter according to any one of claims 2 to 5, wherein the second and third capacitors alternately resonate. 7. A leakage-free non-leakage transformer is provided instead of the leakage transformer, and a second tap of a secondary winding of the transformer and a second tap of a primary winding of the non-leakage transformer are provided. The resonance type DC-DC converter according to claim 2, wherein an inductance is connected between the two. 8. A leakage-free non-leakage transformer is provided instead of the leakage transformer, wherein a second tap of a primary winding of the transformer and a second tap of a primary winding of the non-leakage transformer are provided. The resonance type DC-DC converter according to claim 3, wherein an inductance is connected between the two. 9. A leakage-free non-leakage transformer is provided instead of the leakage transformer, wherein a center tap of the primary winding of the auto transformer and a second tap of the primary winding of the non-leakage transformer are provided. The resonance type DC-DC converter according to claim 4, wherein an inductance is connected therebetween. 10. Instead of the leakage transformer,
A leakage-free non-leakage transformer is provided, and an inductance is connected between the second tap of the first winding of the autotransformer and the second tap of the primary winding of the non-leakage transformer. The resonant DC-DC converter according to claim 5.