KR20090128260A - Power supply using integrated transformer - Google Patents

Abstract

PURPOSE: A power supply unit is provided to suppress thermal unbalance by winding an inductor winding to an outer leg after winding a primary winding and a secondary winding to a center leg. CONSTITUTION: A switching part(200) converts an input DC power into an AC power. A transforming part(300) converts a voltage level of the AC power from the switching part according to a turns ratio, and includes an integrated transformer. The integrated transformer includes a core and a coil group. The core has a first outer leg, a second outer leg, and a center leg. The coil group has a primary winding, a secondary winding, and an inductor winding. The primary winding and the secondary winding are wound to the center leg. The inductor winding is wound to one of the first outer leg and the second outer leg. A rectifying part(400) rectifies the AC power from the transforming part into a DC power. A control part(500) controls a switching duty of the switching part according to a voltage level of the DC power from the rectifying part.

Description

Power supply using integrated transformers {POWER SUPPLY USING INTEGRATED TRANSFORMER}

The present invention relates to a power supply apparatus using an integrated transformer, and more particularly, to a power supply apparatus using a transformer in which a transformer for power conversion and an inductor for stabilizing an output power by the transformer are integrated into one transformer structure.

BACKGROUND ART In general, a power supply device that converts a commercial AC power source into a DC power source that is required for an information device such as a personal computer, and home electronic products such as an air conditioner, an audio and visual device, is mainly used.

With the various developments of the above-mentioned electronic products, a power supply device for outputting a DC power of several hundred watts or more is required, and a light and small product size is also required while requiring the high output DC power.

As part of satisfying the above-described needs, integration of a transformer, which is a magnetic element used for power conversion, and an output inductor for stabilizing the converted power supply are required in a power supply device.

1 is a block diagram showing the structure of a transformer integrating a transformer and an output inductor employed in a conventional power supply device.

Referring to FIG. 1, a conventional integrated transformer 1 consists of a magnetic core and a winding.

The magnetic core faces each other and extends from the first and second support parts 1a and 1b and the first and second support parts 1a and 1b of a predetermined length having one end and the other end so as to extend the first and second support parts 1a and 1b. First and second outer legs 1c, 1d and center legs 1e which magnetically engage 1b).

The winding includes primary windings P1 and P2, secondary windings S1 and S2 electromagnetically coupled to the primary windings P1 and P2, and an inductor coil Lo corresponding to the above-described output inductor. . The primary windings P1 and P2 and the secondary windings S1 and S2 correspond to the above-described transformer for power conversion.

The primary windings P1 and P2 and the secondary windings S1 and S2 are bisected and wound around the first and second outer legs 1c and 1d, respectively, and the inductor winding Lo is wound around the center leg 1e. do.

The conventional integrated transformer described above has the following problems.

First, the magnetic core uses a commercial EE core or a commercial EI core, in which the primary and secondary windings P1, which are responsible for power conversion to the outer legs 1c and 1d having a cross-sectional area smaller than the center leg 1e, are used. In the form of winding P2, S1, S2, the direct current flux by the inductor winding Lo of the center leg 1e and the alternating magnetic flux of the primary and secondary windings P1, P2, S1, S2 are added to the outer leg 1c. , Magnetic flux density of 1d) becomes very high. In particular, since the DC component is included in the magnetic poles of the primary and secondary windings P1, P2, S1, and S2, the transformer can be easily self-saturated by a small asymmetric circuit element or AC asymmetric operation of the power supply.

Secondly, the center leg 1e is only wound with the inductor winding Lo so that only the magnetic flux caused by the inductor flows and the cross section is larger than the outer legs 1c and 1d, so that the core loss is very small. Therefore, most of the losses are concentrated in the outer legs 1c and 1d in which the primary and secondary windings P1, P2, S1 and S2 are wound, so that the center legs 1e and thermal unbalance occur.

Third, since the primary and secondary windings (P1, P2, S1, S2) are wound on the outer legs (1c, 1d), if there are many windings, there is no core to wrap and the magnetic flux can spread to the outside, which may cause electromagnetic interference problems. In addition, since the transformer winding is divided into two, the coupling coefficient between the primary windings P1 and P2 and the secondary windings S1 and S2 is small.

In order to solve the above problems, an object of the present invention is to wind the primary and secondary windings corresponding to the transformer for power conversion to the center leg and the inductor winding for stabilizing the output power by the transformer by dividing the outer leg into one The present invention provides a transformer integrated in a transformer structure and a power supply device using the same.

In order to achieve the above object, one technical aspect of the present invention is a switching unit for alternately switching an input DC power source to an AC power source and a voltage level of the AC power source from the switching unit according to a preset winding ratio. A transformer for converting, a rectifier for rectifying AC power from the transformer, and outputting a DC power, and a controller for controlling the switching duty of the switching unit according to the voltage level of the DC power from the rectifier. The first and second supports are formed to have a predetermined length and spaced apart from each other, and the first and second supports are formed between the first and second supports, respectively, and are magnetically coupled to the first and second supports. Has two outer legs and a center leg, and the first and second support portions are formed at one end and opposite to the one end, and the one end and the other end. Has a middle formed in the middle, the first and the second outer leg magnetically connects each one end and each other end of the first and second support, respectively, the center leg is the first and second support A core that magnetically connects each of the interruptions, a primary winding wound on the center leg, and an electromagnetic coupling wound around the center leg to electromagnetic coupling with the primary winding to convert the voltage level of the AC power source according to the turns ratio. A coil group having a secondary winding and an inductor winding wound around at least one outer leg of the first and second outer legs and stabilizing the level-converted AC power from the secondary winding, wherein the first and second outer legs The cross section of the leg and the cross section of the center leg have a width in the longitudinal direction of the first and second support portions, respectively, and the width of the first and second outer legs are respectively the center. It is to provide a power supply using an integrated transformer, characterized in that more than 0.5 times the width of the leg and less than 2 times.

According to one technical aspect of the present invention, the core may be composed of a combination of an EE core or an EI core.

According to one technical aspect of the present invention, the primary winding, the secondary winding and the inductor winding may be wound in the same direction with each other.

According to one technical aspect of the present invention, the secondary winding may be formed with an intermediate tab electrically connected to the DC power output terminal of the rectifier.

According to one technical aspect of the present invention, the rectifying unit may include a plurality of rectifying switches to rectify the AC power from the transformer unit in a full-wave rectifying method or a half-wave rectifying method.

According to one technical aspect of the present invention, the rectifying unit forms a first and second rectifying switch for rectifying the AC power from the inductor winding of the transformer, the inductor winding and the LC filter to form the first and the first 2 may include a capacitor for stabilizing the rectified power from the switch for rectification.

According to one technical aspect of the present invention, the inductor winding may include a first inductor winding wound around a first outer leg of the core and a second inductor winding wound around a second outer leg of the core, One end of the first inductor winding may be electrically connected to one end of the secondary winding, and the other end of the first inductor winding may be electrically connected to the first rectifying switch of the rectifying unit. The other end of the secondary winding may be electrically connected, and the other end of the second inductor winding may be electrically connected to a second rectifying switch of the rectifying unit.

According to one technical aspect of the present invention, the switching unit power supply using an integrated transformer, characterized in that for selecting one of the full bridge, half-bridge and push-pull switching method.

According to one technical aspect of the present invention, the rectifying switch may be composed of a semiconductor switching device including a diode or a metal oxide semiconductor field-effect transistor (MOSFET).

According to one technical aspect of the present invention, the controller may control the switching duty of the switching unit in a phase shift pulse width modulation (PWM) scheme.

According to one technical aspect of the present invention, the power supply device may further include a power factor correction unit for rectifying the commercial AC power and correcting the power factor to provide the input DC power.

According to the present invention, unlike the conventional commercially available EE core or EI core, the cross-sectional width of the outer leg of the core is formed more than 0.5 times and less than 2 times the cross-sectional width of the center leg, respectively, the primary winding to form a transformer Is wound around the center leg and the inductor winding to the outer leg to dissipate the heat generated during power conversion to all legs to suppress thermal unbalance and increase the coupling coefficient of the primary winding to achieve high efficiency of power conversion. have.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a configuration diagram showing an embodiment of a power supply apparatus using the integrated transformer of the present invention.

2, an embodiment of the power supply apparatus of the present invention includes a power factor correcting unit 100, a switching unit 200, a transformer unit 300, a rectifier 400, and a controller 500.

The power factor corrector 100 rectifies the commercial AC power, corrects the power factor of the rectified power, and transmits the DC power Vg to the switching unit 200.

The switching unit 200 is configured in a full bridge method having four switches Q1, Q2, Q3, and Q4, and alternately switches according to the switching signals sw1, sw2, sw3, and sw4 to supply DC power (Vg). ) Is converted into AC power and transferred to the transformer unit 300. (D1 to D4 denote body diodes of Q1 to Q4, respectively.)

The transformer 300 includes the integrated transformer shown in FIG. 4, and transforms the voltage level of the AC power supply from the switching unit 200 according to the winding ratio between the primary winding P1 and the secondary windings S1 and S2. Transfer to the rectifier 400.

The rectifier 400 is configured in a half-wave rectification method having two rectifier switches Q5 and Q6 including the body diodes D5 and D6 in consideration of the conduction loss, so that the inductor winding Lo1 of the transformer 300 is reduced. The AC power supply from Lo2) is rectified and converted into DC power supply Vo having a preset voltage level. At this time, the rectifier 400 includes a capacitor Co at the output terminal to stabilize the DC power supply Vo. Although not shown, the rectifier 400 may also be configured in a full-wave rectification method having four switches for rectification.

The controller 500 switches the control signals sw1, sw2, sw3, and sw4 to variably control the switching duty of the alternate switching of the switching unit 200 according to the voltage level of the DC power supply Vo from the rectifier 400. To 200. The control unit 500 switches the phases of the control signals sw1, sw2, sw3, and sw4 according to the voltage level of the DC power supply Vo to switch the phase by a phase shift PWM (Phase Shift Pulse Width Modulation) method. Can be controlled.

3 is a block diagram showing another embodiment of a power supply apparatus using the integrated transformer of the present invention.

Referring to FIG. 3 together with FIG. 2, the switching unit 200 may be configured in a half-bridge method having two switches Q1 and Q2 connected in parallel to an input DC power supply Vg terminal. .

4A and 4B are schematic diagrams of integrated transformers employed in the transformer 300 of the power supply apparatus of the present invention.

Referring to FIG. 4A, the integrated transformer 310 of the present invention includes a core formed of a magnetic element and a coil group wound around the core.

The core has supports 311, 312 and legs 313, 314, 315.

The support parts 311 and 312 may include a first support part 311 and a second support part 312, and the first and second support parts 311 and 312 may be formed of magnetic elements having a predetermined length, respectively. The other end formed on the opposite side in the longitudinal direction and a middle stop between the one end and the other end.

Legs 313, 314 and 315 are composed of first and second outer legs 313 and 314 and a center leg 315. The first outer legs 313 magnetically connect each end of the first and second support portions 311 and 312. The second outer leg 314 magnetically connects the other ends of the first and second support parts 311 and 312. The center leg 315 magnetically connects each interruption of the first and second supports 311 and 312. Air gaps for determining the inductance of the transformer may be formed in the first and second outer legs 313 and 314 and the center leg 315, respectively.

The core has an EE core structure, but the cross-sectional width (t) of the first and second outer legs (313,314) is 0.5 times compared to the cross-sectional width (t) of the center leg (315), unlike conventional commercial EE cores. Preferably, the cross section widths 313 and 314 of the outer leg and the cross section width of the center leg 315 may be configured to be the same in consideration of mass production as illustrated.

In addition, as shown in FIG. 4B, the core may have an EI core structure, and the cross-sectional width 2t of the first and second outer legs 313 and 314 may be compared with the cross-sectional width t of the center leg 315. It may be configured twice.

Electrical characteristics of the cross-sectional widths of the first and second outer legs 313 and 314 and the cross-sectional width of the center leg 315 will be described with reference to FIG. 10.

The coil group has a primary winding P1 that is responsible for power conversion and secondary windings S1, S2 and an inductor winding Lo1, Lo2 that is responsible for output stabilization.

The primary winding P1 and the secondary windings S1 and S2 are wound around the center leg 315 of the core portion, and the inductor windings Lo1 and Lo2 are wound around the outer legs 313 and 314. The inductor windings Lo1 and Lo2 may be wound on at least one outer leg of the first and second outer legs 313 and 314. However, in consideration of thermal balance, the inductor windings Lo1 and Lo2 may be dividedly wound on the first and second outer legs 313 and 314. desirable

The inductor windings Lo1 and Lo2 may be configured of a first inductor winding Lo1 wound around the first outer leg 313 and a second inductor winding Lo2 wound around the second outer leg 314. One end of the first inductor winding Lo1 is electrically connected to one end of the secondary winding S1, and the other end of the first inductor winding Lo1 is electrically connected to the first rectifying switch Q5 of the rectifier 400. do. Similarly, one end of the second inductor winding Lo2 is electrically connected to the other end of the secondary winding S2, and the other end of the second inductor winding Lo2 is electrically connected to the second rectifying switch Q6 of the rectifier 400. Can be connected.

The secondary windings S1 and S2 may be formed with a center tap electrically connected to the DC power output terminal of the rectifier 400. (Np shown in FIG. 4A represents the number of turns of the primary winding P1, Ns1 and Ns2 are the number of turns of the secondary windings S1 and S2, respectively, and NL1 and NL2 are the number of turns of the inductor windings Lo1 and Lo2, respectively.)

Although not shown in the drawings of the integrated transformer described above, it is obvious to those skilled in the art that the core is coupled to the inside of the bobbin, which is an electrical insulator, and the coil group is wound around the outer circumferential surface of the bobbin.

5 is an operation waveform diagram of the power supply device shown in FIG. 2.

Referring to Fig. 5 along with Fig. 2, an operation waveform of the main part of the power supply apparatus of the present invention can be seen.

6 (a) and 6 (b) are diagrams illustrating the operation in the operation mode 1 shown in FIG. 5.

Referring to FIG. 6 together with FIGS. 2 and 5, in operation mode 1 (see FIG. 5), the first switch Q1 and the fourth switch Q4 of the switching unit 200 are simultaneously turned on and the rectifier 400 may be turned on. The first rectifying switch Q5 is turned on. Positive DC voltage is applied to the secondary windings S1 and S2 of the transformer unit 300 so that power is transferred from the primary winding P1 to the secondary windings S1 and S2 and the current Io of the first inductor winding Lo1 is applied. ) Increases linearly. At this time, no current flows through the second inductor winding Lo2. In the graph of FIG. 5, Im denotes a current flowing through the magnetizing inductor, Vab denotes a voltage between the a and b nodes of FIG. 2, and Ip denotes a primary side current, I5 and I6 denote first and second rectifier switches. It means the current flowing in (Q5, Q6).

FIG. 6A shows the conduction state in the integrated magnetic circuit, and the thick solid line shown in the figure indicates the flow of current. Fig. 6B shows Fig. 6A as an equivalent magnetic circuit. The arrows marked down on each side indicate the reference direction of the flux rate of the leg. The equation of the magnetic flux rate from (a) and 6 (b) of Fig. 6 is the same as the following equation (1) (in Fig. 6 (b) FL1, FL2 is the magnetic force of the inductor winding, Fp is the primary winding) Pressing force, Fs1, Fs2 is the presser force of the secondary winding, Fg1 is the presser force of the permeance of the first outer leg, Fg2 is the presser force of the air gap of the second outer leg S magnetic force, Pg is the air gap permission of the first or second outer leg, Pgc is the air gap permission of the center leg)

(Equation 1)

Where N _p, N _s, N _L represents the number of turns of the respective primary winding (P1) the winding number, the secondary winding (S1, S2) Volume line number and the first inductor winding (Lo1) of, Φ <sub>^{`1,</sup></sub> Φ <sub>2</sub> <sup>`,`} Φ _c each represents a magnetic flux of the first and second outer legs and a center leg. V _g and V _o represent the input voltage and the output voltage. Solving this equation, the flux rate on each side is expressed by Equation 2 below.

(Equation 2)

Therefore, the magnetic flux of the middle side corresponding to the center leg increases linearly by the positive voltage applied to the primary winding P1. The magnetic flux on the right side increases linearly to store energy in the air gap. The winding on the left side is connected in series with the secondary winding (S1), and half of the magnetic flux on the middle side flows, so it can be regarded as a secondary winding having a number of turns of NL / 2.

7 (a) and 7 (b) are diagrams showing the operation in the operation mode 2 shown in FIG.

Referring to FIG. 7 together with FIGS. 2 and 5, in operation mode 2 (see FIG. 5), the first switch Q1 and the second switch Q2 are simultaneously turned on so that the primary side of the transformer 300 is freewheeled. In the freewheeling state, the voltage on the secondary side of the transformer 300 becomes zero. Therefore, the current Io flowing in the first inductor winding Lo1 decreases linearly through the first rectifying switch Q5 as shown in the graph of FIG. 5. No current flows through the second inductor winding Lo2 yet. Fig. 7A shows the conduction state in the integrated magnetic circuit, and the thick solid line shown in the figure shows the flow of current. FIG. 7B shows an equivalent magnetic circuit in FIG. 7A. 7 (a) and 7 (b), the equation regarding the magnetic flux rate can be set as Equation 3 as follows.

(Equation 3)

Solving the above Equation 3, the magnetic flux rate flowing on each side corresponding to each leg is as shown in Equation 4 below.

(Equation 4)

Referring to Equation 4, the magnetic flux on the center side is constant and the magnetic flux on the outer side decreases linearly.

8A and 8B are diagrams illustrating the operation in the operation mode 3 shown in FIG. 5.

Referring to FIG. 8 together with FIGS. 2 and 5, in operation mode 3 (see FIG. 5), the second switch Q2 and the third switch Q3 are simultaneously conducted, and the switch for the second rectification of the rectifier 400 is performed. Q6 is conducting. Therefore, a negative DC voltage is applied to the secondary windings S1 and S2 of the transformer unit 300 so that electric power is transferred from the primary winding P1 to the secondary windings S1 and S2, and the second inductor winding Lo2 The current Io increases linearly as shown in FIG. 5. At this time, no current flows through the first inductor winding Lo1. Fig. 8A shows the conduction state in the integrated magnetic circuit, and the thick solid line shown in the figure shows the flow of current. FIG. 8B shows an equivalent magnetic circuit under the condition of FIG. 8A. According to (a) and (b) of FIG. 8, the magnetic flux rate may be expressed as in Equation 5 below.

(Equation 5)

Solving the above Equation 5, the magnetic flux rate on each side can be obtained as shown in Equation 6 below.

(Equation 6)

Referring to Equation 6, the magnetic flux of the center side decreases linearly by the positive voltage applied to the primary winding P1. The magnetic flux on the left side increases linearly to store energy in the voids. The winding on the right side is connected in series with the secondary winding S2, and since half of the magnetic flux on the middle side flows, it can be viewed as a secondary winding having a turn number of NL / 2.

9A and 9B are views showing an operation in the operation mode 4 shown in FIG. 5.

Referring to FIG. 9 together with FIGS. 2 and 5, in the operation mode 4 (see FIG. 5), the third switch Q3 and the fourth switch Q4 are simultaneously conducted so that the primary side of the transformer 300 is freewheeled. In the freewheeling state, the voltage on the secondary side of the transformer 300 becomes zero. Therefore, the current Io flowing in the second inductor winding Lo2 decreases linearly through the second rectifying switch Q6 as shown in the graph of FIG. 5. No current flows through the first inductor winding Lo1 yet. Fig. 9A shows the conduction state in the integrated magnetic circuit, and the thick solid line shown in the figure shows the flow of current. FIG. 9B shows an equivalent magnetic circuit under the condition of FIG. 9A. According to (a) and (b) of FIG. 9, the magnetic flux rate may be expressed as in Equation 7 below.

(Equation 7)

Solving the above equation (7) can be obtained as shown in the following equation (8).

(Equation 8)

In the above Equation 8, the magnetic flux on the center side is constant, and the magnetic flux on the outer side decreases linearly.

FIG. 10 is a main waveform diagram of the magnetic equivalent circuit shown in FIGS. 6B to 9B. Referring to FIG. 10, flux rates and flux waveforms at the first and second outer and center legs of the integrated transformer are shown. ^{_{Here, Φ `1, Φ` 2}} , Φ `c comprises first and second outer and instantaneous value of the magnetic flux of the legs and the center _{leg, Φ 1, Φ 2, Φ} c comprises first and second outer legs and a center leg Represents the average magnetic flux of. The magnetic flux of the center leg flows only the alternating magnetic flux caused by the transformer. In the first and second outer legs, the alternating magnetic flux by the transformer flows in half evenly and is added to the direct current magnetic flux by the inductor winding.

Therefore, the peak value of the magnetic flux of the first and second outer legs is the largest and serves as a criterion for selecting the core in the above-described embodiment. In other words, when a general core having a cross-section of the outer side is about half the cross-sectional area of the center side is used for the magnetic circuit integration, the core side cannot be effectively used, and the core size becomes very large. Therefore, in order to reduce the volume of the core, as shown in FIGS. 4A and 4B, when the core of the outer side is 1 to 2 times larger than the width of the middle side, the maximum power density can be obtained at the given volume.

In FIG. 4, the voltage conversion ratio M (D) is obtained by selecting one of the first and second outer legs from the condition that the average magnetic flux ratio becomes zero, as shown in Equation 9 below.

(9)

Here, D represents the ratio of the steady state and inductor windings Lo1 and Lo2 play the same role as secondary windings S1 and S2. Therefore, the output DC power supply (V _o ) can be obtained by appropriately selecting the ratio of the ratio and the winding ratio of the integrated transformer.

The inductance of one of the inductor windings of the inductor windings Lo1 and Lo2 is given by the following equation (10).

(Equation 10)

Here, P _g is the permeability of the gap located on the outer side of the equation (11).

(Equation 11)

Where μ ₀ is the permeability in air, and A _o and l _g represent the cross-sectional areas of the first and second outer legs and the length of the air gap formed in the legs. Accordingly, the magnetization inductance is as shown in Equation 12 below.

(Equation 12)

The peak-to-peak alternating flux and the maximum magnetic flux of the first and second outer legs are expressed by Equation 13 below.

(Equation 13)

Here, f _s represents the switching frequency of the switching unit 200. Since there is no direct current flux in the center leg, only the alternating magnetic flux by the transformer exists, and the magnitude of the peak-to-peak alternating magnetic flux and the maximum magnetic flux are shown in Equation 14 below.

(Equation 14)

From the maximum magnetic flux density of each leg, it is possible to determine whether magnetic saturation has occurred in the core of the transformer, and the core loss generated in each leg can be obtained from the alternating magnetic flux density.

11 (a) to 11 (d) are graphs showing electromagnetic characteristics of the integrated transformer of the present invention. In FIGS. 11A to 11C, the voltage level of the input DC power is set to 400 V, the output DC power is set to 1.2 W, and the voltage level is set to 12 V in the power supply of FIG. 2. The switching frequency of 200 is 100 kHz, the number of turns N _p of the primary winding P1 is 40, the number of turns N _s of the secondary windings S1 and S2 is 2, and the inductor windings Lo1 and Lo2 The number of turns N _L represents the electrical characteristic curve according to the ratio of the width of the center leg to the width of the outer leg of the integrated transformer under the condition of rated load when set to 2.

In general, in the case of commercially available cores, the ratio of the width of the center leg to the width of the outer leg is about 2. Referring to (a) of FIG. 11, in the case of a commercial core, the peak magnetic flux density of the center leg is much smaller than that of the outer leg, so that the cross-sectional area of the center leg is not effectively used. Accordingly, as shown in FIG. 11B, the power conversion efficiency is lower even though the cross section of the center leg is larger than that of the outer leg. The reason is that the core loss of the center leg is small but the loss is increased.

On the other hand, when the ratio of the width of the center leg to the width of the outer leg is less than 2 as applied to the integrated transformer of the present invention, it can be seen that the peak magnetic flux density of the center leg is increased. From the point where the outer leg width ratio is 1, the peak magnetic flux density of the center leg is rapidly increased. In addition, when the ratio of the width of the center leg to the width of the outer leg is 1/2, the peak magnetic flux density of the center leg and the outer leg becomes equal. Accordingly, referring to FIG. 11B, when the ratio of the width of the center leg to the width of the outer leg is less than 2, it can be seen that the power conversion efficiency of the center leg increases. It can be seen that the power density increases about 20% when the center leg width and the outer leg width are the same as those of the commercial core where the center leg width is twice the width of the outer leg.

Therefore, it can be seen that the use of the integrated transformer of the present invention can greatly increase power conversion efficiency and power density.

FIG. 11 (d) shows an efficiency curve according to load under the condition of a core shape obtained by adjusting the width and thickness so that the width of the center leg is equal to the width of the outer leg, and the width of each leg is the same square. It can be seen that the efficiency is 98.74% at rated load and the maximum efficiency is about 99% at 0.3 to 0.5 load.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, but is defined by the claims below, and the configuration of the present invention may be modified in various ways without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art that the present invention may be changed and modified.

1 is a block diagram of an integrated transformer employed in a conventional power supply device.

2 is a block diagram showing an embodiment of a power supply apparatus using the integrated transformer of the present invention.

3 is a block diagram showing another embodiment of a power supply apparatus using the integrated transformer of the present invention.

4 (a) and 4 (b) are diagrams showing embodiments of an integrated transformer employed in the power supply apparatus of the present invention.

5 is an operational waveform diagram of a power supply apparatus using the integrated transformer of the present invention shown in FIG.

6 (a) and 6 (b) show the operation of the integrated transformer in the operation mode 1 shown in FIG.

7 (a) and 7 (b) show the operation of the integrated transformer in the operation mode 2 shown in FIG.

8 (a) and (b) show the operation of the integrated transformer in the operation mode 3 shown in FIG.

9 (a) and (b) show the operation of the integrated transformer in the operation mode 4 shown in FIG.

10 is a main waveform diagram of the magnetic circuit of FIGS. 6 to 9;

11A to 11D are graphs showing electromagnetic characteristics of an integrated transformer employed in the power supply apparatus of the present invention.

<Detailed Description of Major Symbols in Drawing>

100 ... Power factor correction unit 200 ... Switching unit

300 ... Transformer 400 ... Rectifier

500 ... Control section 310 ... Integrated transformer

311 ... First support 312 ... Second support

313 ... Outer Legs 314 ... Outer Legs 2nd

315 ... Center leg P1 ... Primary winding

S1, S2 ... Secondary winding Lo1, Lo2 ... First, second inductor winding

Claims (11)

A switching unit which alternately switches an input DC power source and converts the AC power into an AC power source; A transformer for converting a voltage level of an AC power supply from the switching unit according to a preset winding ratio; A rectifier for rectifying AC power from the transformer and outputting DC power; And A control unit for controlling a switching duty of the switching unit according to the voltage level of the DC power supply from the rectifying unit, The transformer unit First and second supports each having a predetermined length and spaced apart from each other at a predetermined interval, and formed between the first and second supports, respectively, and first and second magnetically coupled to the first and second supports. Has an outer leg and a center leg, the first and second support portions have one end and the other end formed opposite to the one end and a middle end formed in the middle of the one end and the other end, and the first and second outer leg have the first leg. And magnetically connecting the respective ends of the second support and the other ends, respectively, and the center leg magnetically connecting the respective interruptions of the first and second supports. And A primary winding wound around the center leg, a secondary winding wound around the center leg and electromagnetically coupled to the primary winding to convert a voltage level of the AC power source according to the turns ratio, and at least one of the first and second outer legs Has a coil group wound around one outer leg and having an inductor winding to stabilize the level-converted AC power from the secondary winding, Cross-sections of the first and second outer legs and cross-sections of the center legs respectively have longitudinal widths of the first and second support portions, and widths of the first and second outer legs are widths of the center legs, respectively. A power supply using an integrated transformer, characterized in that more than 0.5 times and less than 2 times. The method of claim 1, The core is a power supply using an integrated transformer, characterized in that consisting of a combination of EE core or EI core. The method of claim 1, And the primary winding, the secondary winding and the inductor winding are wound in the same direction with each other. The method of claim 1, The secondary winding is a power supply using an integrated transformer, characterized in that the intermediate tab is electrically connected to the DC power output terminal of the rectifier is formed. The method of claim 4, wherein The rectifier is provided with a plurality of rectifier switches for rectifying the AC power from the transformer in a full-wave rectification method or a half-wave rectification method. The method of claim 5, wherein the rectifying unit First and second rectifying switches for rectifying AC power from the inductor winding of the transformer unit; And A capacitor which forms an LC filter with the inductor winding to stabilize the rectified power from the first and second rectifying switches Power supply using an integrated transformer comprising a. The method of claim 6, wherein the inductor winding A first inductor winding wound around a first outer leg of the core; And A second inductor winding wound around a second outer leg of the core, One end of the first inductor winding is electrically connected to one end of the secondary winding, and the other end of the first inductor winding is electrically connected to the first rectifying switch of the rectifying unit. One end of the second inductor winding is electrically connected to the other end of the secondary winding, and the other end of the second inductor winding is electrically connected to the second rectifying switch of the rectifying unit. Device. The method of claim 1, The switching unit power supply using an integrated transformer, characterized in that for selecting one of the full bridge, half-bridge and push-pull switching method. The method of claim 5, And said rectifier switch comprises a semiconductor switching device comprising a diode or a metal oxide semiconductor field-effect transistor (MOSFET). The method of claim 1, And the control unit controls a switching duty of the switching unit by a phase shift PWM (Phase Shift Pulse Width Modulation) method. The method of claim 1, The power supply unit further comprises a power factor correction unit for rectifying the commercial AC power and correcting the power factor to provide the input DC power.

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