JP5824211B2 - Composite magnetic component and switching power supply using the same - Google Patents

Description

  The present invention relates to a composite magnetic component and a switching power supply device using the same.

  A technique related to a composite magnetic component in which magnetic components constituting a transformer and a reactor used in a switching power supply device and the like are integrated is disclosed.

  In Patent Document 1, a primary side winding and a secondary side winding constituting a transformer are wound around a central leg portion of an E-type core, and an I-type core disposed via an E-type core and a magnetic gap is disclosed. A composite magnetic component configured by winding a reactor winding formed by extending a primary winding of a transformer around a core is disclosed. Patent Document 2 discloses a composite transformer in which a reactor and a transformer are integrated in a composite manner. The two windings constituting the reactor are wound so that the magnetic flux directions cancel each other, and are wound so as to alternately overlap each other in the transformer core.

JP 2009-59995 A JP 2009-284647 A

  In the above prior art, the magnetic coupling of the windings constituting the reactor is not considered, and it is difficult to handle the reactor and the transformer independently. In other words, in the technique described in Patent Document 1, the E-type core has many magnetic branch paths as viewed from the windings constituting the reactor, and the reactor and the transformer cannot be handled independently. Further, in the technique described in Patent Document 2, a tightly coupled reactor and two reactors can be integrated, but a configuration for obtaining a transformer structure is not disclosed.

  In the technique described in Patent Document 1, since the magnetic circuit is formed by combining the E-type core and the I-type core, the magnetic flux passing through the primary winding and the secondary winding of the transformer is 2 The magnetic gap between the two cores passes through, and the magnetic coupling between the primary winding and the secondary winding is weakened.

  In either of Patent Documents 1 and 2, there is no description about a configuration in which a transformer is provided with a center tap. If a center tap is provided in the coil constituting the transformer and a current is supplied from the center tap, the independent operation of the reactor and the transformer cannot be maintained. That is, since the lengths of the windings are different from the center tap, the respective resistance values are different, and the current balance is lost.

The present invention provides a reactor core including a reactor core, a reactor winding wound around the reactor core, and both ends of the reactor core and a magnetic gap, and the reactor core Is a separate member, a transformer core that constitutes a circular magnetic circuit, and a primary side of a transformer that is divided into a plurality of spatially symmetrical portions with respect to the reactor core and wound around the transformer core A transformer unit including a winding and a secondary winding of the transformer that is divided into a plurality of spatially symmetrical portions with respect to the reactor core and wound around the transformer core. The reactor winding, the primary side winding and the secondary side winding are independent windings, and the reactor winding is not wound around the transformer core, and the primary side Winding and Serial secondary winding is a composite magnetic component, wherein not wound around the core for reactor.

  Here, the reactor winding is wound so as to form a magnetic flux in a direction opposite to the first reactor winding and the magnetic flux formed in the reactor core by the first reactor winding in the reactor core. The second reactor winding is preferably included.

  The reactor winding is wound so as to form a magnetic flux in the same direction as a magnetic flux formed in the reactor core by the first reactor winding and the first reactor winding. The second reactor winding is preferably included.

  In addition, it is preferable that the reactor core has a magnetic gap between the first reactor winding and the second reactor winding.

  In addition, it is preferable to provide a plurality of the reactor portions.

  Further, it is preferable that at least one of the primary side winding and the secondary side winding is provided with a center tap divided at the midpoint of the winding.

  It is also preferable to realize a switching power supply device using the composite magnetic component.

  According to the present invention, the number of components can be reduced in a circuit that requires a reactor and a transformer.

It is a perspective view which shows the structure of the composite magnetic component in embodiment of this invention. It is a schematic diagram which shows the structure of the composite magnetic component in embodiment of this invention. It is a schematic diagram which shows another example of a structure of the composite magnetic component in embodiment of this invention. It is a perspective view which shows another example of a structure of the composite magnetic component in embodiment of this invention. It is a perspective view which shows another example of a structure of the composite magnetic component in embodiment of this invention. It is a figure for demonstrating a magnetic circuit model. It is a figure for demonstrating a magnetic circuit model. It is a schematic diagram for demonstrating a magnetic circuit model. It is an equivalent circuit diagram for demonstrating a magnetic circuit model. It is a schematic diagram for demonstrating a magnetic circuit model. It is an equivalent circuit diagram for demonstrating a magnetic circuit model. It is an equivalent circuit diagram for demonstrating the effect | action of the composite magnetic component in embodiment of this invention. It is a schematic diagram for demonstrating the effect | action of the composite magnetic component in embodiment of this invention. It is an equivalent circuit diagram for demonstrating the effect | action of the composite magnetic component in embodiment of this invention. It is a schematic diagram for demonstrating the effect | action of the composite magnetic component in embodiment of this invention. It is an equivalent circuit diagram for demonstrating the effect | action of the composite magnetic component in embodiment of this invention. It is a schematic diagram for demonstrating the effect | action of the composite magnetic component in embodiment of this invention. It is a figure which shows the multiport power supply circuit which is a usage example of the composite magnetic component in embodiment of this invention. It is a perspective view which shows another example of a structure of the composite magnetic component in embodiment of this invention. It is a figure for demonstrating the effect | action when comprising a composite magnetic component with a laminated steel plate.

<Composition of composite magnetic parts>
As shown in FIG. 1, a composite magnetic component 100 according to an embodiment of the present invention includes a transformer core 10, a transformer primary winding 12 (12a, 12b), and a transformer secondary winding 14 (14a, 14b). ), The reactor core 16 and the reactor winding 18 (18a, 18b). FIG. 2 schematically shows the configuration of the composite magnetic component 100 shown as a perspective view in FIG.

  The transformer core 10 is a magnetic material, and forms a magnetic circuit through which a magnetic flux passing through the primary winding 12 and the secondary winding 14 passes. The transformer core 10 is preferably a loop-shaped magnetic member that does not have a magnetic gap in the middle so as to constitute a circular magnetic circuit. For example, the transformer core 10 is preferably a loop-shaped rectangular shape having four sides as shown in FIG. By using the transformer core 10 that does not have a magnetic gap in the middle, the magnetic coupling rate between the primary winding 12 and the secondary winding 14 described later can be made close to 100%. The conversion efficiency can be increased.

  The primary winding 12 and the secondary winding 14 of the transformer are provided in combination with the transformer core 10 in the composite magnetic component 100 to form a transformer. That is, the primary side winding 12 and the secondary side winding 14 are provided for converting the voltage in accordance with the ratio of the number of turns. The primary side winding 12 and the secondary side winding 14 are configured by winding a conductor around the transformer core 10. As the primary winding 12 and the secondary winding 14, for example, copper wires are preferably used.

  The primary side winding 12 is divided and wound as primary side windings 12 a and 12 b at two locations on the transformer core 10. In the present embodiment, the primary windings 12 a and 12 b are wound around the left and right sides of the transformer core 10 so that magnetic fluxes in the same direction are formed in the transformer core 10. Here, in order to generate magnetic fluxes symmetrically, it is preferable that the numbers of turns of the primary windings 12a and 12b are equal. Further, the secondary side winding 14 is divided and wound as secondary side windings 14 a and 14 b at two locations of the transformer core 10. In the present embodiment, the secondary windings 14 a and 14 b are wound around the left and right sides of the transformer core 10 so that magnetic fluxes in the same direction are formed in the transformer core 10. Here, in order to generate magnetic flux symmetrically, it is preferable that the number of turns of the secondary windings 14a and 14b be equal.

  The reactor core 16 is a magnetic member that forms a magnetic circuit through which a magnetic flux passing through the reactor winding 18 passes. The reactor core 16 is magnetically coupled to the transformer core 10 and is disposed such that a magnetic gap (air gap) 20 is formed between at least both ends and the transformer core 10. Further, the reactor core 16 is divided between the primary side windings 12a and 12b wound in two portions and between the secondary side windings 14a and 14b wound in two portions. It is preferable that the primary windings 12a and 12b and the secondary windings 14a and 14b are arranged symmetrically with respect to each other.

  For example, as shown in FIG. 1, the reactor core 16 spans between the primary windings 12a and 12b and the secondary windings 14a and 14b on the side surface 10a of the rectangular transformer core 10. Placed in. The magnetic coupling between the transformer core 10 and the reactor core 16 will be described later.

  Reactor windings 18a and 18b are provided in combination with reactor core 16 in composite magnetic component 100 to form a reactor. Reactor windings 18 a and 18 b are configured by winding a conductor around reactor core 16. As the reactor windings 18a and 18b, for example, copper wires are preferably used.

  Reactor windings 18a and 18b can be adjusted to an arbitrary value by winding the reactor core 16 at a free turn ratio. As a result, current smoothing can be performed using a change in inductance according to the current direction.

  As shown in the schematic diagram of FIG. 3, a magnetic gap 20 may be provided in the middle of the reactor core 16 if necessary. Further, the reactor core 16 may be disposed anywhere as long as it is symmetrical with respect to the transformer core 10. For example, as shown in FIG. 4, three reactor cores 16 may be provided on both sides and the center of the transformer core 10. Moreover, as shown in FIG. 5, the reactor core 16 may be provided in a direction shifted by 90 ° with respect to the reactor core 16 of FIGS. A plurality of these arrangements may be combined.

  Moreover, since the reactor windings 18a and 18b shown in FIGS. 1 and 2 are wound in a direction in which the magnetic fluxes cancel each other, they are coupled in the same phase direction. However, the present invention is not limited to this, and if the reactor windings 18a and 18b are wound in a direction in which the magnetic flux is strengthened, they are coupled in the opposite phase direction. Further, only one of the reactor windings 18a and 18b may be wound. Also in this case, a reactor having no magnetic coupling with the transformer can be obtained.

<Magnetic circuit model>
FIG. 6 shows a magnetic flux model of the reverse phase current. In FIG. 6, when the magnetic resistance is R, the magnetic flux density B = φ / S generated in the core by the winding is expressed by Equations (1) and (2). Here, N is the number of turns, I is the current, S is the core cross-sectional area, L is the core length, μ ₀ is the vacuum permeability, and μr is the relative permeability.
B × S = 1 / R × N × I (1)
R = L / (μr × μo × S) (2)

The magnetic flux φ has a property that it is easy to pass through a path having a small magnetic resistance and difficult to pass through a high path. In the case where a gap is provided in the core as shown in FIG. 7, assuming that the magnetic resistance is Ra, the magnetic flux density Ba = φa / S generated in the core by the winding is expressed by equations (3) and (4). Here, Lg is the gap length.
Ba × S = 1 / Ra × N × I (3)
Ra = 1 / [[[(μo × S) / Lg] + [(μr × μo × S) / L]] (4)

  Therefore, when a magnetic material having a large μr is used for the core, the magnetoresistance Ra is almost concentrated in the gap portion, and the magnetoresistance Ra can be designed by adjusting the gap length. At this time, care must be taken so that the magnetic flux density Ba does not exceed the maximum magnetic flux density Bmax of the core.

The inductance formed by the winding is determined by the magnetic flux density linked to the winding, and the inductance L when there is no gap is expressed by Equation (5).
L = N × N / R (5)

Inductance La in the case of having a gap is expressed by Equation (6).
La = N × N / Ra (6)

In general, when designing a transformer, it is necessary to design the transformer so as to generate a large magnetic flux with as small an excitation current as possible by designing the transformer so that the magnetic resistance is reduced and the inductance L is increased. That is, when the excitation current increases, losses such as copper loss and iron loss increase, leading to deterioration in transformer conversion efficiency and coupling rate. Further, the primary side winding 12 and the secondary side winding of the transformer based on the formula (7) so that the magnetic flux density Bpeak (T) generated when the maximum voltage Vmax is applied does not exceed the maximum saturation magnetic flux density Bmax of the transformer core 10. It is necessary to design the number of turns of the wire 14 and the cross-sectional area S of the transformer core 10. Here, f is the operating frequency of the transformer.
Bpeak (T) = Vmax / (4 × N × f × S) (7)

8 and 9 show the principle of the coupled inductor. Based on the above formulas (1) to (6), based on the core length, cross-sectional area, gap length, etc., the windings 30 and 32 according to the interlinkage magnetic flux of the windings 30 and 32 (4 turns). The inductors 38a and 38b formed by the above are determined. Here, the value of the inductor generated when the magnetic flux 36 generated by the winding 32 is linked to the winding 30 is L (30). Actually, since the same current flows in the winding 30 and the winding 32, the magnetic flux 34 and the magnetic flux 36 cancel each other, the magnetic flux interlinking with the windings 30 and 32 is reduced, and the inductors 38a and 38b are lowered. To do. Assuming that a (0 <a <1) is the ratio of the magnetic flux interlinking with the winding 30 in the magnetic flux 36 generated by the winding 32, the value Lb1 (reverse phase current flow) of each inductor 38a, 38b shown in FIG. (Hour) is expressed by Equation (8).
Lb1 = (1-a) × L (30) (8)

Further, as shown in FIGS. 10 and 11, a similar phenomenon occurs when a current of the same phase is passed through the windings 30 and 32. That is, the magnetic flux 34 and the magnetic flux 36 strengthen each other when the common-mode current flows, and the value Lb2 (when the common-mode current flows) of the inductors 39a and 39b in FIG. 11 is expressed by Expression (9).
Lb2 = (1 + a) × L (30) (9)

Thus, it can be used as an inductor whose inductance varies depending on the current direction. In addition, the number of winding turns, the shape of the core, the gap length, etc. so as to satisfy Expression (10) so that the magnetic flux density Bpeak (Lb) generated in the core does not exceed the maximum saturation magnetic flux density Bmax of the core. Need to design.
Bpeak (Lb) = (a × N × Imax) / (Ra × S) (10)

<Operation of composite magnetic parts>
FIG. 12 and FIG. 13 show an operation example in the case where excitation is caused to flow through the primary winding 12 of the transformer of the composite magnetic component 100 in the present embodiment. When a current is supplied from the excitation power source 40 to the load 41, an excitation current flows through the primary winding 12 as shown in FIG. Thereby, an exciting magnetic flux is generated and interlinks with the secondary winding 14. As paths for the magnetic flux generated by the primary winding 12, paths 44 and 46 through the reactor core 16 can be considered, but the transformer core 10 has no gap 20 and is designed to have a very small magnetic resistance in the path 42. Since the magnetic resistance of the paths 44 and 46 is designed to be extremely large due to the gap 20 between the transformer core 10 and the reactor core 16, almost all the generated magnetic flux flows through the path 42.

  Further, even if a small amount of magnetic flux leaks to the reactor core 16, since the turns ratio of the primary side winding 12a (left side) and the primary side winding 12a (left side) is equal, the primary side winding 12a (left side) The magnetic flux 48a generated and the magnetic flux 48b generated by the primary side winding 12b (right side) cancel each other in the reactor core 16, and the reactor windings 18a and 18b are not affected.

  As shown in FIGS. 14 and 15, the same effect is obtained when excitation is performed from the secondary winding 14. That is, the action on the transformer side does not interfere with the reactor side.

  16 and 17 show an example in which the reactor windings 18a and 18b are made to act as coupled inductors. When a current is supplied from the exciting power supply 40 to the load 41, an exciting current flows through the reactor winding 18a as shown in FIG. As a result, magnetic flux is generated in the paths 50 and 52. The path 50 is divided into the left and right sides of the transformer core 10 via the gap 20, and magnetic flux is evenly generated there. The magnetic flux passing through the path 50 is linked to the reactor windings 18a and 18b. That is, the magnetic flux of the path 50 and the reactor windings 18a and 18b are magnetically coupled. Further, the path 52 goes around the reactor winding 18 a through a magnetic resistance portion such as the gap 20. Therefore, by adjusting the number of turns of the reactor winding 18a, the length of the gap 20 between the transformer core 10 and the reactor core 16, and the leakage flux through the path 52, the values of the inductors 54 and 56 and the mutual Can be determined. In the case of the circuit of FIG. 16, a current flows through the reactor winding 18b and a magnetic flux is generated. However, since the magnetic resistance in the path is equal, the operation is the same as that of FIG.

  Here, since the magnetic flux generated by one of the reactor windings 18a and 18b and the magnetic flux linked to the other reactor (for example, the magnetic flux passing through the path 50) pass through the transformer core 10, the primary winding for the transformer. 12 and the secondary winding 14 are also linked. However, among the magnetic flux components passing through the path 50, the component interlinked with the primary winding 12a and the magnetic flux component interlinked with the primary winding 12b are equal, and each of the primary windings 12a and 12b is generated. Voltage cancels out, and the magnetic flux through path 50 does not affect the operation of the transformer. Similarly, among the magnetic flux components passing through the path 50, for example, the component interlinking with the secondary winding 14a and the magnetic flux component interlinking with the secondary winding 14b are equal, and the secondary winding 14a, The voltage generated by each of 14b cancels and the magnetic flux through path 50 does not affect the operation of the transformer.

  Thus, according to composite magnetic component 100 in the present embodiment, a transformer and a reactor can be configured as one magnetic component by using a part of the configuration as a common core, and a reactor and a transformer are required. The number of parts in the circuit can be reduced. As a result, the magnetic device can be manufactured at a lower cost. Moreover, according to the composite magnetic component 100, the mutual magnetic influence of a transformer part and a reactor part can be made small, and a transformer and a reactor can be handled independently. Further, the transformer core 10 of the composite magnetic component 100 has no magnetic gap or the like, and the magnetic coupling between the primary side winding 12 and the secondary side winding 14 of the transformer can be strengthened. The efficiency of voltage conversion can be increased.

<Specific usage example>
FIG. 18 shows an example in which the composite magnetic component 100 according to the embodiment of the present invention is applied to a multiport power supply circuit 200. The multiport power supply circuit 200 is a kind of switching power supply circuit, and can control the voltage and power of the ports A to D. The composite magnetic component 100 includes a transformer 102 provided with center taps 60 and 62 and reactors 104 and 106 coupled in phase.

  FIG. 19 is a diagram illustrating a configuration of the composite magnetic component 100 applied to the multi-port power supply circuit 200. As shown in FIG. 19, center taps 60 and 62 are provided between the primary windings 12a and 12b for the transformer of the composite magnetic component 100 and between the secondary windings 14a and 14b. Reactor windings 18 a, 18 b, 18 c, and 18 d are wound around reactor cores 16 a and 16 b that are disposed at two dividing points of transformer core 10 via gap 20, respectively. In the multiport power supply circuit 200 as described above, the reactor windings 18 a and 18 b constitute the reactor 104, and the reactor windings 18 c and 18 d constitute the reactor 106. In FIG. 19, the arrow indicates the winding direction of the winding.

  By arranging via the gap 20, the magnetic resistance between the transformer core 10 and the reactor cores 16a and 16b is increased, and the primary windings 12a and 12b or secondary windings 14a and 14b for the transformer are increased. Can be prevented from flowing into the reactor cores 16a and 16b, whereby the above-described canceling effect can be more reliably obtained.

  Further, the reactor cores 16a and 16b are determined in shape, size, material and the like so as not to be magnetically saturated by the magnetic flux generated by the reactor windings 18a, 18b, 18c and 18d as shown in the above formula (10). To do. The transformer core 10 is a path between the magnetic flux generated by the primary windings 12a and 12b and the secondary windings 14a and 14b and the magnetic flux generated by the reactor windings 18a, 18b, 18c, and 18d. The shape, size, material, and the like are determined based on the above formula (7) and formula (10).

  Thus, since the transformer and the reactor can be configured to be independent (not magnetically coupled), the transformer 102 and the reactors 104 and 106 can be configured as one composite magnetic component 100.

  When the transformer core 10 and the reactor core 16 are formed by laminating steel plates 74, as shown in FIG. 20, the magnetic resistance is high with respect to the magnetic flux in the laminating direction of the steel plates 74 (arrow 70). When magnetic flux passes in the direction, it becomes a cause of eddy current generation in the surface of the steel plate 74. Therefore, it is preferable to arrange the reactor cores 16a and 16b so that the end portions extend along the direction (arrow 72) perpendicular to the stacking direction (arrow 70) of the steel plates 74 of the transformer core 10. It is. Thereby, the magnetic flux generated from the reactor windings 18a, 18b, 18c, and 18d flows into the transformer core 10 along the direction (arrow 72) perpendicular to the stacking direction (arrow 70) of the steel plates 74. Can be reduced, and the generation of eddy currents in the surface of the steel plate 74 can also be suppressed. Thereby, the loss of the composite magnetic component 100 can be reduced.

  When using a core whose magnetic characteristics do not change depending on the magnetic flux direction, such as a dust magnetic material, the degree of freedom of relative arrangement of the transformer core 10 and the reactor core 16 can be increased.

  10 transformer core, 10a side surface, 12 (12a, 12b) primary winding, 14 (14a, 14b) secondary winding, 16 (16a, 16b) reactor core, 18 (18a, 18b, 18c, 18d) ) Reactor winding, 30, 32 winding, 34, 36 magnetic flux, 38a, 38b inductor, 39a, 39b inductor, 40 power supply, 41 load, 42, 44, 46 path, 48a, 48b magnetic flux, 50, 52 path, 54 , 56 Inductor, 60, 62 Center tap, 70, 72 Arrow, 74 Steel plate, 100 Composite magnetic component, 102 Transformer, 104, 106 Reactor, 200 Multiport power supply circuit.

Claims (7)

A reactor core;
A reactor winding wound around the reactor core; and
Including a reactor section,
A transformer core that is disposed through magnetic gaps and both ends of the reactor core, is a separate member from the reactor core, and constitutes a circular magnetic circuit;
A primary winding of a transformer that is divided into a plurality of spatially symmetrical places with respect to the reactor core and wound around the transformer core;
A secondary winding of a transformer divided into a plurality of spatially symmetrical places with respect to the reactor core and wound around the transformer core;
Including a transformer section,
With
The reactor winding, the primary side winding and the secondary side winding are independent windings, and the reactor winding is not wound around the transformer core, and the primary side winding The composite magnetic component according to claim 1, wherein the wire and the secondary winding are not wound around the reactor core. The composite magnetic component according to claim 1,
The reactor winding is a first reactor winding and a second winding wound to form a magnetic flux in a direction opposite to the magnetic flux formed in the reactor core by the first reactor winding in the reactor core. A composite magnetic member comprising a reactor winding. The composite magnetic component according to claim 1,
The reactor winding is wound around so as to form a first reactor winding and a magnetic flux in the same direction as a magnetic flux formed in the reactor core by the first reactor winding in the reactor core. A composite magnetic member comprising a reactor winding. The composite magnetic component according to claim 2 or 3,
The composite magnetic component, wherein the reactor core has a magnetic gap between the first reactor winding and the second reactor winding. The composite magnetic component according to any one of claims 1 to 4,
A composite magnetic component comprising a plurality of the reactor portions. The composite magnetic component according to any one of claims 1 to 5,
At least one of the primary side winding and the secondary side winding is provided with a center tap divided at the midpoint of the winding.   A switching power supply apparatus using the composite magnetic component according to claim 1.

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