TWI678873B - Interleaved dc-dc forward converter - Google Patents

Abstract

A out-of-phase DC-DC forward converter receives an input voltage and converts the input voltage into an output voltage to a load, and includes a transformer, a first switch, a second switch, a first diode, and a second diode. , The third diode, the capacitor, the first inductor, the second inductor, the output capacitor, and the control unit. The first switch and the second switch are controlled to switch between a conducting state and a non-conducting state. A pulse wave modulation signal and a second pulse wave modulation signal, and the first pulse wave modulation signal and the second pulse wave modulation signal are out of phase with each other. The first switch receives the first pulse wave modulation signal and is controlled by the first pulse wave modulation signal. The second switch receives the second pulse wave modulation signal and is controlled by it, so that the present invention reduces the use of components, reduces the cost, provides a high step-down ratio, and the output current is low ripple.

Description

Out-of-phase DC-DC forward converter

The present invention relates to a staggered phase DC-DC forward converter, especially using a first switch and a second switch to be controlled for out-of-phase operation, cooperated with a transformer, a first inductor, a second inductor and a Capacitor's out-of-phase DC-DC forward converter.

Referring to the first figure, a conventional out-of-phase DC-DC forward converter receives an input voltage V _in and converts it into an output voltage V _{o and} provides it to a load R. The DC-DC converter includes a first transformer T _r1 , a second transformer _Tr2 , a first switch _S01 , a second switch _S02 , a first diode _D01 , a second diode _D02 , a third diode _D03 , A fourth diode D ₀₄ , a fifth diode D ₀₅ , a sixth diode D ₀₆ , a first inductor L ₀₁ , a second inductor L ₀₂ , and an output capacitor C _o1 . The first transformer T _r1 has a primary side winding p1, a secondary side winding s1, and a tertiary side winding t1. The second transformer T _r2 has a primary side winding p2, and a secondary side winding s2. And one and three side windings t2. The voltage gain ratio of this conventional out-of-phase DC-DC forward converter is nD, where D is a duty cycle of the first switch and the second switch, and n represents the first transformer T _r1 and the second transformer. turns ratio of the transformer T _{r2, n = N s1 / N p1} = N s2 / N p2, N s1 represents the number of turns of the secondary winding of the first transformer T _r1, N _p1 denotes the first transformer T _r1 of the number of turns of the primary winding, N _s2 denotes the number of turns of the secondary winding of the second transformer T _r2, N _p2 represents the number of turns of the primary winding of the second transformer T _r2. Although this circuit can provide low ripple output current, it uses quite a lot of components and cannot reduce the cost.

Therefore, the object of the present invention is to solve the problem that the conventional out-of-phase DC-DC forward converter uses a large number of components and cannot reduce the cost, and proposes an out-of-phase DC-DC forward converter.

Therefore, the out-of-phase DC-DC forward converter of the present invention receives an input voltage and converts the input voltage into an output voltage to a load, and the out-of-phase DC-DC forward converter includes a transformer, a first A switch, a second switch, a first diode, a second diode, a third diode, a capacitor, a first inductor, a second inductor, an output capacitor, and a control unit .

The transformer is electrically connected to the input voltage, the first switch is electrically connected between the transformer and the input voltage, and is controlled to switch between a conductive state and a non-conductive state, and the second switch is controlled to switch to a conductive state And non-conducting state, the first diode is electrically connected between the transformer and the second switch, the second diode is electrically connected to the transformer, and the third diode is electrically connected to the second switch And the transformer, the capacitor is electrically connected between the first diode and the second diode, the first inductor is electrically connected to the capacitor, and the second inductor is electrically connected to the first inductor and the first inductor Between the three diodes, the output capacitor is electrically connected between the first inductor and the third diode. The voltage across the output capacitor is the output voltage. The load is connected in parallel with the output capacitor to receive the output voltage. The control unit outputs a first pulse wave modulation signal and a second pulse wave modulation signal, and the first pulse wave modulation signal and the second pulse wave modulation signal are out of phase with each other, and the first switch receives the The first pulse wave modulates the signal and is subject to the first pulse wave Varying the control signal, the second switch receives the second pulse modulation signal and the second pulse modulation signal and the control subject.

Further, the transformer includes a primary winding and a secondary winding. Each of the primary winding and the secondary winding has a first end and a second end. One end is electrically connected to the positive electrode of the input voltage, and the first switch has a primary connection to the transformer. A first end of a second end of the side winding and a second end of a negative electrode electrically connected to the input voltage, the second switch has a first end and a second end, and the first diode has an electrical connection with the An anode at the first end of the secondary winding of the transformer and a cathode electrically connected to the first end of the second switch, the second diode has an electrode electrically connected to the second end of the secondary winding of the transformer. An anode and a cathode, the third diode having an anode electrically connected to the anode of the second diode, and a cathode electrically connected to the second end of the second switch, the capacitor having an electrical connection to the first two A first end of the cathode of the pole body and a second end of the cathode of the second diode body, the first inductor has a first end electrically connected to the second end of the capacitor, and a second end The second inductor has a first terminal electrically connected to the cathode of the third diode and a second terminal electrically connected to the second terminal of the first inductor, and the output capacitor has a first terminal electrically connected to the first inductor; A first end of the two ends and a second end of the anode electrically connected to the third diode.

Further, the out-of-phase DC-DC forward converter further includes a fourth diode, the transformer further includes a tertiary winding, the tertiary winding has a first end and a second end, and the fourth The diode has an anode electrically connected to the second end of the tertiary winding of the transformer and a cathode electrically connected to the positive pole of the input voltage, and the first end of the tertiary winding of the transformer is electrically connected to the negative pole of the input voltage.

Further, the first end of the primary winding, the secondary winding, and the tertiary winding of the transformer are all polar point terminals, and the second end of the primary winding, the secondary winding, and the tertiary winding of the transformer are all one. Non-polar point end.

Further, when the first switch is in a conductive state and the second switch is in a non-conductive state, the energy of the input voltage is transmitted to the capacitor, the first inductor, the output capacitor, and the load through the transformer, and at the same time, is stored. The energy in the second inductor is also transferred to the output capacitor and the load. When the first switch and the second switch are in a non-conducting state, the first inductor, the second inductor, and the output The energy stored in the capacitor is released to the load at the same time. When the first switch is in the non-conducting state and the second switch is in the conducting state, the energy stored in the capacitor is transferred to the second inductor, the output capacitor, and the load. At the same time, the energy stored in the first inductor is also transferred to the output capacitor and the load.

Further, a voltage gain ratio of the output voltage to the input voltage is nD / 2, where D is a duty cycle between the first switch and the second switch switched between a conducting state and a non-conducting state, and D is between Between 0 and 1, n = N ₂ / N ₁ , n represents the turns ratio of the transformer, N ₂ represents the number of turns of the secondary winding, and N ₁ represents the number of turns of the primary winding.

Further, the inductance of the first inductor is the same as the inductance of the second inductor.

Further, the first switch and the second switch are two N-type metal oxide semiconductor field effect transistors, respectively.

According to the above technical features, the following effects can be achieved:

1. The first switch and the second switch are controlled for out-of-phase operation, and cooperate with the functions of the transformer, the first inductor, the second inductor, and the capacitor, so that the present invention can reduce the number of components used and reduce costs. Reduce, not only can provide a higher step-down ratio, and the output current also achieves the effect of low ripple.

2. The voltage gain ratio of the present invention is nD / 2, where D is the duty cycle of the first switch and the second switch, and n is the turns ratio of the transformer.

(1) ‧‧‧Control unit

(V _in ) ‧‧‧Input voltage

(V _o ) ‧‧‧Output voltage

(R) ‧‧‧Load

(T _r ) ‧‧‧Transformer

(11) ‧‧‧Primary winding

(21) ‧‧‧Secondary winding

(31) ‧‧‧Third side winding

(S ₁ ) ‧‧‧First switch

(S ₂ ) ‧‧‧Second switch

(D ₁ ) ‧‧‧First Diode

(D ₂ ) ‧‧‧Second Diode

(D ₃ ) ‧‧‧Third Diode

(D ₄ ) ‧‧‧ Fourth Diode

(C) ‧‧‧Capacitance

(L ₁ ) ‧‧‧First inductor

(L ₂ ) ‧‧‧Second inductance

(C _o ) ‧‧‧Output capacitor

(V _C ) ‧‧‧Capacitance across voltage

(V _o ) ‧‧‧Span voltage of output capacitor

(v _GS1 ) ‧‧‧The gate-source signal of the first switch

(v _GS2 ) ‧‧‧The gate-source signal of the second switch

(i _L1 ) ‧‧‧Current flowing through the first inductor

(i _L2 ) ‧‧‧Current flowing through the second inductor

(i _LL ) ‧‧‧Output current

(i _S1 ) ‧‧‧Current flowing through the first switch

(i _S2 ) ‧‧‧Current flowing through the second switch

(i _D1 ) ‧‧‧Current flowing through the first diode

(i _D2 ) ‧‧‧Current flowing through the second diode

(i _D3 ) ‧‧‧Current flowing through the third diode

(T _S ) ‧‧‧The cycle time of the first pulse wave modulation signal and the second pulse wave modulation signal

(D) ‧‧‧ Duty cycle of the first switch and the second switch

(n) ‧‧‧Transformer turns ratio

[First Figure] is a circuit diagram illustrating a conventional out-of-phase DC-DC forward converter.

[Second figure] is a circuit diagram illustrating an embodiment of the out-of-phase DC-DC forward converter according to the present invention.

[Third figure] is an operation timing chart explaining the parameter timing of this embodiment.

[Fourth Figure] is a circuit diagram illustrating that this embodiment operates in a first stage.

[Fifth Figure] is a circuit diagram illustrating that the embodiment operates in a second stage and a fourth stage.

[Sixth Figure] is a circuit diagram illustrating that this embodiment operates in a third stage.

[Seventh Figure] is a graph illustrating the voltage gain of the out-of-phase DC-DC forward converter according to the present invention.

[Eighth Figure] An analog waveform diagram illustrating the gate-source signal of a first switch and the gate-source signal of a second switch in this embodiment.

[Ninth figure] is an analog waveform diagram illustrating an analog waveform of an output current, a current flowing through a first inductor, and a current flowing through a second inductor in this embodiment.

[Tenth figure] is an analog waveform diagram illustrating an analog waveform of an input voltage, a voltage across a capacitor, and an output voltage of this embodiment.

[Eleventh figure] is an analog waveform diagram illustrating the analog waveform of the current flowing through a first switch and a first diode in this embodiment.

[Twelfth figure] is an analog waveform diagram illustrating an analog waveform of current flowing through a second diode and a third diode in this embodiment.

Based on the above technical features, the main effects of the out-of-phase DC-DC forward converter of the present invention will be clearly shown in the following embodiments.

Referring to the second figure, an embodiment of the out-of-phase DC-DC forward converter according to the present invention is suitable for receiving an input voltage V _in and converting the input voltage V _in into an output voltage V _o to a load R. The input The voltage V _in is a DC voltage, and the output voltage V _o is also a DC voltage. The out-of-phase DC-DC forward converter includes a transformer T _r , a first switch S ₁ , and a second switch S ₂ . A first diode D ₁ , a second diode D ₂ , a third diode D ₃ , a fourth diode D ₄ , a capacitor C, a first inductor L ₁ , a second The inductor L ₂ , an output capacitor _Co and a control unit 1.

The transformer T _r includes a primary winding 11, a secondary winding 21, and a tertiary winding 31, each of the primary winding 11, the secondary winding 21, and the tertiary winding 31. It has a first end and a second end. The primary winding 11, the secondary winding 21, and the first end of the tertiary winding 31 are all polar point ends. The primary winding 11, the secondary Both the side winding 21 and the second end of the tertiary side winding 31 are non-polar point ends. A first terminal of the primary winding 11 is electrically connected to a positive electrode of the input voltage V _in , and a first terminal of the tertiary winding 31 is electrically connected to a negative electrode of the input voltage V _in .

The first switch S ₁ is an N-type metal-oxide-semiconductor field-effect transistor, and has a first terminal electrically connected to the second terminal of the primary winding 11 of the transformer T _r , and a terminal electrically connected to the input voltage V _in . A second terminal of the negative electrode is controlled to switch between a conducting state and a non-conducting state, wherein the first terminal of the first switch S ₁ is a drain and the second terminal is a source. The second switch S ₂ is also an N-type metal oxide semiconductor field effect transistor, and has a first terminal and a second terminal, and is controlled to switch between a conducting state and a non-conducting state. The first end of the second switch S ₂ is a drain, and the second end is a source.

The first diode D ₁ has an anode electrically connected to the first end of the secondary winding 21 of the transformer T _r and a cathode electrically connected to the first end of the second switch S ₂ . The second diode D ₂ has an anode and a cathode that are electrically connected to the second end of the secondary winding 21 of the transformer T _r . The third diode D ₃ has an anode electrically connected to the anode of the second diode D ₂ and a cathode electrically connected to the second end of the second switch S ₂ . The fourth diode D ₄ has an anode electrically connected to the second end of the tertiary winding 31 of the transformer T _r , and a cathode electrically connected to the positive electrode of the input voltage V _in .

The capacitor C has a first terminal electrically connected to the cathode of the first diode D ₁ and a second terminal electrically connected to the cathode of the second diode D ₂ . In addition, the capacitance of the capacitor C is sufficiently large, and the trans-voltage V _{C of} the capacitor _C can be regarded as a fixed value.

The first inductor L ₁ has a first terminal electrically connected to a second terminal of the capacitor C, and a second terminal. The second inductor L ₂ has a first terminal electrically connected to the cathode of the third diode D ₃ and a second terminal electrically connected to the second terminal of the first inductor L ₁ . The inductance of the first inductor L ₁ is the same as the inductance of the second inductor L ₂ .

The output capacitor _Co has a first terminal electrically connected to the second terminal of the first inductor L ₁ , and a second terminal electrically connected to the anode of the third diode D ₃ . The voltage across the output capacitor C _o is the output voltage V _o , and the capacitance of the output capacitor C _o is sufficiently large, the voltage across the output capacitor C _o can be regarded as a fixed value, and the load R is electrically connected to the output capacitor C _o first and second ends to receive the output voltage V _o.

The control unit 1 outputs a first pulse wave modulation signal and a second pulse wave modulation signal, and the first pulse wave modulation signal and the second pulse wave modulation signal are out of phase with each other. The first switch S ₁ receives the first pulse wave modulation signal and is controlled by the first pulse wave modulation signal to switch between a conducting state and a non-conducting state. The second switch S ₂ receives the second pulse wave modulation signal and is controlled by the second pulse wave modulation signal to switch between a conducting state and a non-conducting state. The phase error control unit 1 controls the first switch S ₁ and the second switch S _2, it will be further described hereinafter the first switch S ₁ and the second switch S ₂ is four-phase switching mode.

Referring to the third figure, this is an operation timing diagram of this embodiment, wherein the parameter v _GS1 represents the voltage of the first pulse wave modulation signal controlling whether the first switch S ₁ is turned on, and is also the gate of the first switch S _{1 -Source} signal, parameter v _GS2 represents the voltage of the second pulse wave modulation signal that controls whether the second switch S ₂ is turned on, and is also the gate-source signal of the second switch S ₂ , parameters i _L1 , i _L2 Respectively the currents flowing through the first inductor L ₁ and the second inductor L ₂ , the parameter i _LL represents the output current, and the parameters i _S1 and i _S2 represent the first switch S ₁ and the second switch S _{2 respectively.} The parameters i _D1 , i _D2 , and i _D3 respectively represent the currents flowing through the first diode D ₁ , the second diode D ₂ , and the third diode D ₃ , and the parameter T _S represents The cycle time of the first pulse wave modulation signal and the second pulse wave modulation signal, and the parameter D is a responsibility between the first switch S ₁ and the second switch S ₂ switched between a conducting state and a non-conducting state. Period, and D is between 0 and 1.

Refer to the fourth to sixth figures, which are circuit diagrams of this embodiment operating in four stages, in which components that are conducting or functioning are represented by solid lines, components that are not conducting or functioning are represented by dashed lines, and the transformer T _r The role of the tertiary winding 31 and the fourth diode D ₄ is to solve the problem of magnetic flux reset, which is not the focus of the present invention, and is common to those skilled in the art. Therefore, for simplicity, The circuit diagram of the six diagrams is omitted and will not be repeated here.

The first stage (time: t ₀ -t ₁ ):

See FIG third and fourth diagram, wherein the first switch S ₁ of the gate - source signal v _GS1 greater than zero and the first switch S ₁ is turned on state, the second switch S ₂ of the gate - source signal v _{GS2 is} equal to zero and the second switch S ₂ is non-conducting, and the second diode D ₂ is non-conducting.

The current path in the first stage is shown by the arrow in the fourth figure. The input voltage V _in via the energy in the winding 11 to the secondary side of the transformer T _r of the primary winding 21 so that the first diode D ₁ is turned on, coming from the secondary winding 21 side of the transformer T _r is The energy is transmitted to the capacitor C, the first inductor L ₁ , the output capacitor C _o , and the load R through the first diode D ₁ , and at the same time, the energy stored in the second inductor L ₂ causes the first The triode D _{3 is} turned on, and the energy of the second inductor L ₂ is also transferred to the output capacitor _Co and the load R. Therefore, the current flowing through the first inductor L ₁ increases linearly and flows through the first inductor L ₁ . The current of the two inductors L ₂ decreases linearly. When the time is t ₁ , the first switch S ₁ and the second switch S ₂ are controlled to switch to a non-conducting state, and the first phase ends.

The second stage (time: t ₁ -t ₂ ):

See FIG third and fifth FIG, wherein the first switch S ₁ of the gate - source signal v _GS1, the second switch S ₂ of the gate - source signal v _GS2 is equal to zero, the first switch S _1, the The second switch S _{2 is in} a non-conducting state, and the currents i _S1 and i _S2 flowing through the first switch S ₁ and the second switch S ₂ are zero. The transformer T _r and the capacitor C have no effect. One diode D ₁ is non-conducting.

The current path in the second stage is shown by the arrow in the fifth figure. The first inductor L ₁ , the second inductor L ₂ , and the energy stored in the output capacitor _Co are simultaneously released to the load R. Therefore, the current flowing through the first inductor L ₁ and the second inductor L ₂ is The linear decrease is achieved. When the time is t ₂ and the second switch S ₂ is controlled to be switched to the conducting state, the second phase ends.

The third stage (time: t ₂ -t ₃ ):

Referring to the third and sixth figures, the gate-source signal v _{GS1 of} the first switch S ₁ is equal to zero and is in a non-conducting state, and the gate-source signal v _{GS2 of} the second switch S ₂ is greater than zero and is In the conducting state, the current i _S1 flowing through the first switch S ₁ is zero, the transformer T _{r has} no effect, and the first diode D ₁ and the third diode D ₃ are not conducting.

The current path in the third stage is shown by the arrow in the sixth figure. The energy stored in the capacitor C is transmitted to the second inductor L ₂ , the output capacitor C _o , and the load R, and at the same time, the energy stored in the first inductor L ₁ is also transmitted to the output capacitor C _o and the The load R, therefore, the current i _L1 flowing through the first inductor L ₁ decreases linearly, and the current i _L2 flowing through the second inductor L ₂ increases linearly. When the time is t ₃ , the second switch S ₂ receives When the control is switched to the non-conducting state, the third phase ends.

The fourth stage (time: t ₃ -t ₄ ):

Referring back to the third and fifth figures, the fourth stage is the same as the second stage, in which the gate-source signal v _{GS1 of} the first switch S _{1 and} the gate-source of the second switch S ₂ The signal v _{GS2 is} equal to zero, the first switch S ₁ and the second switch S ₂ are both non-conductive, and the currents i _S1 and i _S2 flowing through the first switch S ₁ and the second switch S ₂ are zero. The transformer T _r and the capacitor C have no effect, and the first diode D ₁ is not conductive.

The current path in the fourth stage is shown by the arrow in the fifth figure, and the analysis process will not be repeated here. When the time is t ₄ and the first switch S ₁ is controlled to be switched to the on state, the fourth phase ends, and returns to the first phase again to start a new cycle.

In the first stage, the second stage, the third stage, and the fourth stage, the output voltage V _o and the input voltage can be obtained from the first inductor L ₁ and the second inductor L ₂ according to the volt-second balance principle. V _in voltage gain ratio nD / 2, _{where, n = N 2 / N 1} , n denotes the turns ratio of the transformer T _r, N ₂ represents the number of turns of the secondary winding 21, N ₁ represents the primary The number of turns of the side winding 11.

Referring to the seventh figure, the voltage gain of the out-of-phase DC-DC forward converter according to the present invention is under the conditions that the transformer T _{r has} a turns ratio of 1, 0.5, and 0.25. From this figure, it can be seen that the present invention can provide High buck ratio.

In the operation of the present invention, the input voltage V _in is 200 volts, the duty cycle D of about 0.24, the turns ratio of the transformer T _r was 1 / 3.5, to give the output voltage V _o is a 12 volt, full output power of 100W The analog waveforms are shown in Figures 8 through 12.

See FIG Eighth, for a first switch S ₁ of the gate - source signal v _GS1, the second switch S ₂ of the gate - source signal v _GS2 analog waveform. The horizontal axis is time, the scale is 40 μs / div, the vertical axis is voltage, and the scale is 15 V / div. From this figure, it can be seen that the duty cycle D is about 0.24.

See FIG. Ninth, the output current i _LL, L flowing through the first inductor current i _{L1 1,} the current flowing through the analog waveform of the second inductor L ₂ of the i _L2. The horizontal axis is time, the scale is 40 μs / div, the vertical axis is current, and the scale is 2A / div. It can be seen from this figure that the first inductor L ₁ and the second inductor L _{2 both} operate in a continuous conduction mode, and the output current i _LL has a low output current ripple.

Refer to the tenth figure, which is an analog waveform of the input voltage V _in , the cross-voltage V _{C of} the capacitor _C , and the output voltage V _o . The horizontal axis is time, with a scale of 50ms / div, and the vertical axis is voltage, with a scale of 50V / div. From this figure, it can be verified that the present invention can convert a high DC voltage into a low DC voltage to achieve the effect of high step-down ratio.

Referring to FIG. 11, it is an analog waveform of the currents i _S1 and i _D1 flowing through the first switch S ₁ and the first diode D ₁ . The horizontal axis is time, the scale is 40 μs / div, the vertical axis is current, and the scale is 2A / div.

Referring to the twelfth figure, it is an analog waveform of the currents i _D2 and i _D3 flowing through the second diode D ₂ and the third diode D ₃ . The horizontal axis is time, the scale is 40 μs / div, and the vertical axis is current, and the scale is 2A / div. From the display of the above analog waveforms, it is verified that the out-of-phase operation process of the present invention is consistent with the foregoing analysis.

In summary, the above embodiment has the following advantages:

1. By controlling the first switch S ₁ and the second switch S ₂ to operate out of phase, in cooperation with the functions of the transformer T _r , the first inductor L ₁ , the second inductor L ₂ and the capacitor C, The invention can reduce the number of components used, reduce the cost, and not only can provide a higher step-down ratio, but also achieve the effect of low ripple in the output current i _LL .

2. The voltage gain ratio of the present invention is nD / 2, where D is the duty cycle of the first switch S ₁ and the second switch S ₂ , and n is the turns ratio of the transformer T _r .

Based on the description of the above embodiments, the operation, use, and effects of the present invention can be fully understood, but the above-mentioned embodiments are only preferred embodiments of the present invention. It is within the scope of the present invention to limit the scope of implementation of the present invention, that is, simple equivalent changes and modifications made according to the scope of the patent application and the description of the invention.

Claims (8)

A out-of-phase DC-DC forward converter receives an input voltage and converts the input voltage into an output voltage to a load, and the out-of-phase DC-DC forward converter includes: a transformer, electrically connected to the Input voltage; a first switch electrically connected between the transformer and the input voltage and controlled to switch between a conductive state and a non-conductive state; a second switch controlled to switch between a conductive state and a non-conductive state Between states; a first diode is electrically connected between the transformer and the second switch; a second diode is electrically connected to the transformer; a third diode is electrically connected to the second switch And the transformer; a capacitor electrically connected between the first diode and the second diode; a first inductor electrically connected to the capacitor; a second inductor electrically connected to the first inductor And the third diode; an output capacitor is electrically connected between the first inductor and the third diode, the voltage across the output capacitor is the output voltage, and the load is connected in parallel with the output capacitor to receive The output voltage; and a control And outputs a first pulse wave modulation signal and a second pulse wave modulation signal, and the first pulse wave modulation signal and the second pulse wave modulation signal are out of phase with each other, and the first switch receives the first pulse wave modulation signal and the second pulse wave modulation signal. A pulse wave modulation signal is controlled by the first pulse wave modulation signal, and the second switch receives the second pulse wave modulation signal and is controlled by the second pulse wave modulation signal. The out-of-phase DC-DC forward converter according to item 1 of the patent application scope, wherein the transformer includes a primary winding and a secondary winding, and each of the primary winding and the secondary winding One has a first end and a second end, the first end of the primary winding of the transformer is electrically connected to the positive pole of the input voltage, and the first switch has a first connection electrically connected to the second end of the primary winding of the transformer. One end, and a second end electrically connected to the negative electrode of the input voltage, the second switch has a first end and a second end, the first diode has a first end electrically connected to the secondary winding of the transformer An anode at one end and a cathode electrically connected to the first end of the second switch, the second diode has an anode and a cathode electrically connected to the second end of the secondary winding of the transformer, and the first The triode has an anode electrically connected to the anode of the second diode, and a cathode electrically connected to the second end of the second switch. The capacitor has a first electrode electrically connected to the cathode of the first diode. Terminal and one of the cathodes electrically connected to the second diode Two terminals, the first inductor has a first terminal electrically connected to the second terminal of the capacitor, and a second terminal, the second inductor has a first terminal electrically connected to the cathode of the third diode, and A second terminal connected to the second terminal of the first inductor, the output capacitor has a first terminal electrically connected to the second terminal of the first inductor, and a second terminal electrically connected to the anode of the third diode. The out-of-phase DC-DC forward converter according to item 2 of the patent application scope further includes a fourth diode, and the transformer further includes a tertiary winding having a first end and A second end, the fourth diode has an anode electrically connected to the second end of the tertiary winding of the transformer, and a cathode electrically connected to the positive end of the input voltage, and the first end of the tertiary winding of the transformer is electrically connected. Connect the negative terminal of this input voltage. According to the out-of-phase DC-DC forward converter according to item 3 of the scope of patent application, wherein the first end of the primary winding, the secondary winding, and the tertiary winding of the transformer are all polar point ends, the The second ends of the primary winding, the secondary winding, and the tertiary winding of the transformer are all non-polar point ends. The out-of-phase DC-DC forward converter according to item 1 of the scope of patent application, wherein when the first switch is in a conducting state and the second switch is in a non-conducting state, the energy of the input voltage passes through the transformer Transmitted to the capacitor, the first inductor, the output capacitor, and the load, and at the same time, the energy stored in the second inductor is also transmitted to the output capacitor and the load. When the first switch and the second switch are not In the conducting state, the energy stored in the first inductor, the second inductor, and the output capacitor is simultaneously released to the load. When the first switch is in the non-conducting state and the second switch is in the conducting state, it is stored in the capacitor. The energy is transferred to the second inductor, the output capacitor, and the load, and at the same time, the energy stored in the first inductor is also transferred to the output capacitor and the load. According to the out-of-phase DC-DC forward converter according to item 2 of the patent application scope, wherein a voltage gain ratio of the output voltage to the input voltage is nD / 2, where D is the first switch and the first switch The two switches are switched between a duty cycle between the conducting state and the non-conducting state, and D is between 0 and 1, n = N ₂ / N ₁ , n represents the turns ratio of the transformer, and N ₂ represents the secondary The number of turns of the side winding, N ₁ represents the number of turns of the primary side winding. The out-of-phase DC-DC forward converter according to item 1 of the patent application scope, wherein the inductance of the first inductor is the same as the inductance of the second inductor. The out-of-phase DC-DC forward converter according to item 1 of the scope of the patent application, wherein the first switch and the second switch are two N-type metal oxide semiconductor field effect transistors, respectively.