CN105846679B - Transformer and switching power supply device - Google Patents

Transformer and switching power supply device Download PDF

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Publication number
CN105846679B
CN105846679B CN201610045872.9A CN201610045872A CN105846679B CN 105846679 B CN105846679 B CN 105846679B CN 201610045872 A CN201610045872 A CN 201610045872A CN 105846679 B CN105846679 B CN 105846679B
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winding
transformer
windings
primary winding
auxiliary
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CN105846679A (en
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小川纮生
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Tamura Corp
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Tamura Corp
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/30—Fastening or clamping coils, windings, or parts thereof together; Fastening or mounting coils or windings on core, casing, or other support
    • H01F27/306—Fastening or mounting coils or windings on core, casing or other support
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F3/00—Cores, Yokes, or armatures
    • H01F3/10—Composite arrangements of magnetic circuits
    • H01F3/14—Constrictions; Gaps, e.g. air-gaps

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Coils Of Transformers For General Uses (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention provides a transformer and a switching power supply device. The transformer can reduce cross regulation even when the load becomes unbalanced. The switching power supply device uses the transformer. The transformer (T) comprises: a magnetic core (10); a primary winding (11) fitted on the magnetic core (10); two or more secondary windings (12, 13) fitted on the core (10) in such a way that the reels are identical to those of the primary winding (11); and two or more auxiliary windings (14, 16) fitted on the magnetic core (10) in such a manner that the reels are identical to those of the primary winding (11), wherein the auxiliary windings (14, 16) are respectively disposed adjacent to the secondary windings (12, 13), and the auxiliary windings (14, 16) are connected in parallel with each other. A switching power supply device is provided with a transformer (T), a switching element connected to a primary winding (11) of the transformer (T), and a control circuit for controlling the switching element.

Description

Transformer and switching power supply device
Technical Field
The present invention relates to a transformer and a switching power supply device using the same, and more particularly to a structure of the transformer.
Background
In order to operate electric devices and circuits, a stable dc voltage is required, and a switching power supply device has been conventionally used to generate the dc voltage. The switching power supply device rectifies and smoothes a voltage supplied from an external power supply, performs a switching operation by a semiconductor switching element, inputs the rectified voltage to a primary winding of a transformer, and supplies a dc voltage from a secondary winding of the transformer to a load via smoothing by a smoothing circuit. The output voltage is monitored, and the timing of the semiconductor switching element is adjusted by the control circuit so that the output voltage is kept constant.
In such a switching power supply device, a multi-output device is conventionally known. In order to form the device, the transformer has two or more secondary windings in addition to a magnetic core and a primary winding mounted on the magnetic core.
Patent document 1: japanese laid-open patent publication No. H05-049257
In the case of a transformer provided with two or more secondary windings, cross regulation may occur when the load becomes unbalanced. That is, when the current flowing through the load connected to one secondary winding changes, the output voltage of the other secondary winding, which should not be related to the load fluctuation, fluctuates, and the output voltage may become unstable.
Disclosure of Invention
The present invention has been made to solve the above-described problems, and provides a transformer capable of reducing cross regulation even when a load is unbalanced, and a switching power supply device using the transformer.
(1) The transformer of the present invention is characterized by comprising: a magnetic core; a primary winding assembled on the magnetic core; two or more secondary windings fitted on the magnetic core in such a manner that a reel thereof is identical to that of the primary winding; and two or more auxiliary windings fitted on the magnetic core in such a manner that the reels are identical to those of the primary windings, wherein the auxiliary windings are respectively disposed adjacent to the secondary windings, and the auxiliary windings are connected in parallel with each other.
The transformer of the present invention may have the following configuration.
(2) The secondary winding is provided on both sides of the primary winding and closer to the primary winding than the auxiliary winding in a direction of a winding axis of the primary winding.
(3) An air gap is provided in the magnetic core at a position where the primary winding is mounted, and the secondary winding is provided on both sides of the primary winding in a direction of a winding shaft of the primary winding at an equal distance from the air gap.
A switching power supply device according to the present invention is characterized by comprising: a transformer having the structure of (1) above; a switching element connected to a primary winding of the transformer; and a control circuit for controlling the switching element. The transformer may have the structure of (2) or (2) and (3).
According to the present invention, a transformer capable of reducing cross regulation even when a load is unbalanced, and a switching power supply device using the transformer can be obtained.
Drawings
Fig. 1 is a schematic sectional view showing the overall structure of a transformer of embodiment 1.
Fig. 2 is a circuit diagram of the switching power supply device according to embodiment 1.
Fig. 3 is a graph showing a time change of the output voltage of each secondary winding of the transformer according to embodiment 1.
Fig. 4 is a schematic sectional view showing the entire structure of the transformer of embodiment 2.
Fig. 5 is a circuit diagram of the switching power supply device according to embodiment 2.
Fig. 6 is a graph showing the time change of the output voltage (after rectification) from each secondary winding when the load balance is changed in the transformer according to embodiment 1.
Fig. 7 is a graph showing the time change of the output voltage (after rectification) from each secondary winding in the transformer according to embodiment 2 when the load balance is changed.
Fig. 8 shows the output voltage waveform of the secondary winding before rectification, fig. 8(a) shows a case where the current flowing through the secondary winding 12 is 0A (no load) and the current flowing through the secondary winding 13 is 0.1A, and fig. 8(b) shows a case where the current flowing through the secondary winding 12 is 0.1A and the current flowing through the secondary winding 13 is 0A (no load) in contrast.
Fig. 9 is a graph showing a voltage time change of the auxiliary winding of embodiment 1 in the case where the load balance is changed, fig. 9(a) is a case where the current of one secondary winding is set to 0.1A and the current of the other secondary winding is set to 0A, and fig. 9(b) is a case where the current of one secondary winding is set to 0A and the current of the other secondary winding is set to 0.1A, which are opposite to each other.
Fig. 10 is a graph showing the voltage time change of each auxiliary winding of the transformer of embodiment 2.
Fig. 11 shows a voltage waveform (before rectification) when the current of the secondary winding 12 is 0A and the current of the secondary winding 13 is 0.1A.
Fig. 12 is a schematic sectional view showing the entire structure of a transformer of another embodiment.
Fig. 13 is a circuit diagram of a switching power supply device according to another embodiment.
Fig. 14 is a schematic sectional view showing the entire structure of a conventional transformer.
Fig. 15 is a graph showing a temporal change in output voltage from each secondary winding of a conventional transformer.
Fig. 16 is a schematic sectional view showing the entire structure of a conventional transformer.
Fig. 17 is a graph showing a temporal change in output voltage from each secondary winding of a conventional transformer.
Description of the reference symbols
10: a magnetic core; 10 a: a middle foot part; 11: a primary winding; 12. 13 and 17: a secondary winding; 14. 16: an auxiliary winding; 15: an air gap; 21: a switching element; 22: a control circuit; 23. 24: a diode (rectifying unit); 25. 26: a capacitor (smoothing unit); t: a transformer; c: the reels of the primary winding and the secondary winding are in a consistent straight line.
Detailed Description
A transformer and a switching power supply device using the transformer according to an embodiment of the present invention will be described below with reference to the drawings. First, the present transformer will be described, and next, the configuration of a switching power supply device using the present transformer will be described.
[1 ] embodiment 1 ]
[1-1. Structure ]
Fig. 1 is a schematic sectional view showing the overall structure of a transformer of the present embodiment. The transformer T transforms a voltage supplied from an external power supply, and supplies power to a load such as a circuit or an external device connected to the transformer T. As shown in fig. 1, the transformer T has a magnetic core 10, a primary winding 11 fitted on the magnetic core 10, two or more secondary windings 12, 13 (two in this case), and an auxiliary winding 14.
The magnetic core 10 is provided with a straight-line-shaped center leg portion 10a at its center portion. The windings 11 to 14 are attached to the center leg 10a so that the winding axes of the windings 11 to 14 are aligned with each other. An air gap 15 is provided at a portion of the magnetic core 10 where the primary winding 11 is fitted. That is, the center leg portion 10a is provided with an air gap 15. Secondary windings 12 and 13 and auxiliary winding 14 are wound around middle leg portion 10a so as to have a polarity opposite to that of primary winding 11, and magnetic core 10 and windings 11 to 14 are insulated by unillustrated bobbins made of an insulating material such as resin.
The primary winding 11 is connected to an external power supply, and feeds power to the secondary windings 12 and 13 and the auxiliary winding 14. The secondary windings 12 and 13 are connected between their terminals to a load such as an external circuit or an external device, and the power received from the primary winding 11 is connected to these circuit or load. The secondary windings 12 and 13 are connected to a snubber circuit for operating, for example, an IGBT, a MOS, or the like.
The secondary windings 12, 13 are disposed on both sides of the primary winding 11 in the direction of the winding axis of the primary winding 11. In other words, the respective secondary windings 12, 13 are disposed so that both are adjacent to the primary winding 11. Preferably, the primary winding 11 is disposed at an equal distance from the primary winding 11 in the direction of the winding axis of the primary winding 11. Further, the secondary windings 12 and 13 are provided at equal distances from the air gap 15 in the winding direction of the primary winding 11.
In the present embodiment, the secondary windings 12, 13 are equidistant from the primary winding and from the air gap 15 in the direction of the winding axis of the primary winding 11. That is, the secondary windings 12 and 13 are provided symmetrically about the primary winding 11 and symmetrically about the air gap 15.
The auxiliary winding 14 is connected to a control circuit for controlling the switching elements, which will be described later. The auxiliary winding 14 receives power from the primary winding 11 and supplies a driving power supply voltage to the control circuit. The auxiliary winding 14 is arranged beside the secondary winding 13 in such a way that the direction of the winding axis is the same, but may also be arranged beside the other secondary winding 12.
The transformer T having the above-described structure is used for a switching power supply device. Fig. 2 is a circuit diagram of a switching power supply device using the present transformer T. Since the transformer T has a plurality of (two in this case) secondary windings 12 and l3, the switching power supply device of the present embodiment is a multi-output power supply device. The switching power supply device is, for example, a flyback switching power supply, and is used for switching a semiconductor.
Specifically, the switching power supply device includes a transformer T, a switching element 21, a control circuit 22 for controlling the switching element 21, diodes 23 and 24, and capacitors 25 and 26. The device may also have a rectifying/smoothing circuit. The rectifying/smoothing circuit is connected between an external power supply and the primary winding 11 of the transformer T, and rectifies and smoothes a voltage supplied from the external power supply.
The switching element 21 is a semiconductor switching element such as an FET. The switching element 21 is connected to the primary winding 11 of the transformer T, and controls an input voltage to the primary winding 11. The control circuit 22 is configured to include an IC, is connected to the auxiliary winding 14 and the switching element 21 provided on the output side, receives a power supply voltage from the auxiliary winding 14, and controls the on/off time rate of the switching element 21 so as to control the input voltage to the primary winding 11. That is, the control circuit 22 controls the output voltages of the secondary windings 12 and 13 to be kept at predetermined voltages, respectively.
For example, the control circuit 22 includes a voltage monitor unit that detects the voltage of the auxiliary winding 14, a smoothing unit such as a capacitor that smoothes the output voltage from the auxiliary winding 14, an optical coupler including a light emitting element and a light receiving element, and an IC. In this case, when an example of control by the control circuit 22 is shown, first, the output voltage value from the auxiliary winding 14 detected by the voltage monitor means is input to the IC via the smoothing means. The IC calculates the output voltages of the secondary windings 12 and 13 from the voltage values and the winding ratios of the auxiliary winding 14 and the secondary windings 12 and 13, and generates control signals for stabilizing the output voltages of the secondary windings 12 and 13 based on the calculated voltages. Then, the IC outputs the control signal to the light emitting element of the photo coupler connected to the IC. The light emitting element converts the input control signal into an optical signal, and outputs the optical signal to a light receiving element connected to the switching element 21. The light receiving element converts the input optical signal into an electrical signal, and receives the electrical signal to change the time rate of the switching element 21.
Capacitors 25, 26 are connected to the secondary windings 12, 13. Diodes 23 and 24 are connected between the secondary windings 12 and 13 and capacitors 25 and 26, and rectify output voltages from the secondary windings 12 and 13. The rectified voltage is smoothed by capacitors 25 and 26 to generate a dc voltage.
[1-2. Effect ]
(1) The transformer T of the present embodiment includes a core 10, a primary winding 11 mounted on the core 10 so that the respective reels are identical, and two or more secondary windings 12 and 13, wherein the core 10 is provided with an air gap 15 at a portion where the primary winding 11 is mounted, and the secondary windings 12 and 13 are provided on both sides in the direction of the reel C and at equal distances from the air gap 15. This reduces the difference in inductance between the secondary windings 12 and 13 and the difference in coupling coefficient with the primary winding 11, and as shown in fig. 3, it is possible to suppress the output voltages from the secondary windings 12 and 13 from deviating when they are stable.
The effects of the present embodiment will be described in more detail in comparison with the prior art. In the case of the conventional transformer shown in fig. 14 in which the secondary windings 112 and 113 provided on both sides of the primary winding 111 are not equidistant from the air gap 115, for example, when the inductance values of the secondary windings 112 and 113 are in the order of several tens μ H (order), the output voltages from the secondary windings 112 and 113 diverge as shown in fig. 15 when the levels of one bit are different. This is caused by a large difference in inductance values between the secondary windings 112 and 113. While the inductance values are equal only in the tens position in the example of fig. 14, the inductance values of the secondary windings 12 and 13 of the transformer T according to the present embodiment can be 10-1The bits are equal and there is a difference of two bits in the uniformity of the inductance values.
As shown in fig. 16, in the case of a conventional transformer in which the distance between the arrangement position of each of the secondary windings 112 and 113 and the air gap 115 is equal and the distance from the primary winding 111 is different, when the inductance value of the secondary windings 112 and 113 is in the order of several tens μ H, 10 is used-1When the bit levels are different, the output voltages from the secondary windings 112 and 113 diverge as shown in fig. 17. This is due to the difference in coupling with the primary winding 111, although the two inductance values are approximately equal. In the example of FIG. 16, electricityThe sense values are equal only in bits. The coupling coefficient between the secondary windings 112 and 113 and the primary winding 111 is only 10-1The bits are equal. On the other hand, the inductance values of the secondary windings 12 and 13 of the transformer T of the present embodiment can be 10-1The bits are equal and there is a one-bit difference in the uniformity of the inductance values. The coupling coefficient of the transformer T of the present embodiment to the primary winding 11 is 10-2Are equal in level, there is a one-bit difference in the uniformity of the coupling coefficients.
As described above, according to the present embodiment, since the difference between the inductances of the secondary windings 12 and 13 and the difference between the coupling coefficients with the primary winding 11 can be reduced, a transformer capable of suppressing the output voltages from the secondary windings 12 and 13 from deviating in multiples, and a switching power supply device using the transformer are obtained.
[2 ] embodiment 2 ]
[2-1. Structure ]
Embodiment 2 will be described with reference to fig. 4 to 11. The basic structure of embodiment 2 is the same as embodiment 1. Thus, only the differences from embodiment 1 will be described, and the same portions as those of embodiment 1 will be denoted by the same reference numerals and their detailed description will be omitted.
Fig. 4 is a schematic sectional view showing the entire structure of the transformer of embodiment 2. Fig. 5 is a circuit diagram of a switching power supply device using the transformer T of embodiment 2. The difference from embodiment 1 is that two or more (here, two) auxiliary windings 14, 16 are provided.
That is, the difference is that the auxiliary windings 14, 16 are provided adjacent to the secondary windings 12, 13 in the winding direction of the windings 11 to 13, respectively, and the auxiliary windings 14, 16 are connected in parallel with each other. In the present embodiment, the auxiliary windings 14 and 16 are provided so as to be equidistant from the air gap 15 in the winding direction and symmetrical with respect to the air gap 15. However, the auxiliary windings 14, 16 do not necessarily have to be arranged symmetrically with respect to the air gap 15.
In the present embodiment, the secondary windings 12 and 13 are provided closer to the primary winding 11 than the auxiliary windings 14 and 16. The windings 11 to 16 are insulated by bobbins made of an insulating material such as resin. As shown in fig. 5, the auxiliary windings 14 and 16 are also connected in parallel with the control circuit 22.
[2-2. Effect ]
(1) As an example, the operation and effects of the present embodiment will be described in comparison with embodiment 1. In the present embodiment, even when the balance of the loads is unbalanced, such as when different types of loads are connected to the secondary windings 12 and 13, respectively, fluctuation of the output voltages from the secondary windings 12 and 13 can be suppressed. The configuration of the present embodiment can be applied to any transformer having a primary winding and two or more secondary windings.
First, fig. 6 shows waveforms of output voltages of the secondary windings 12 and 13 when the load balance is changed in the configuration of embodiment 1. Specifically, fig. 6 shows an example of an output voltage waveform (after rectification) when the current of the secondary winding 12 is 0A and the current of the secondary winding 13 is 0.1A. The width between the dotted lines of fig. 6 is the width between the maximum output voltage of the secondary winding 12 and the minimum output voltage of the secondary winding 13, and it is known that the interval is about 4.25V.
On the other hand, in the present embodiment, there are provided a core 10, a primary winding 11 fitted on the core 10, two or more secondary windings 12, 13 fitted on the core 10 in such a manner that the winding axis is the same as the winding axis of the primary winding 11, and two or more auxiliary windings 14, 16 fitted on the core 10 in such a manner that the winding axis is the same as the winding axis of the primary winding 11, the auxiliary windings 14, 16 being provided adjacent to the secondary windings 12, 13, respectively, and the auxiliary windings 14, 16 being connected in parallel with each other. This can improve the problem of cross regulation even when the load is unbalanced in balance. For example, fig. 7 shows output voltage waveforms (after rectification) of the secondary windings 12 and 13 when the load balance is changed, and is an example when the current of the secondary winding 12 is 0A and the current of the secondary winding 13 is 0.1A, as in the case of fig. 6. As shown in fig. 7, the width of the one-dot chain line of the maximum output voltage and the minimum output voltage of the secondary windings 12 and 13 is about 2.25V, which is narrower than the width between the broken lines (about 4.25V) in fig. 6, and the variation in the output voltage is small. That is, it is found that the stability of the output voltage is improved and the cross regulation is improved.
The reason for this will be described based on embodiment 1. First, in embodiment 1, when the load becomes unbalanced, distortion occurs in the output voltage waveform of the secondary winding on the no-load side. Fig. 8 shows an example of this. Fig. 8 is a voltage waveform of the secondary winding before rectification. Fig. 8(a) shows an output voltage waveform when the current flowing through the secondary winding 12 is 0A (no load) and the current flowing through the secondary winding 13 is 0.1A, and fig. 8(b) shows an output voltage waveform when the load imbalance is reversed and the current flowing through the secondary winding 12 is 0.1A and the current flowing through the secondary winding 13 is 0A (no load). Thus, the distortion of the output voltage waveform on the no-load side means that the output voltage changes by the amount of the distortion.
Further, when distortion occurs in the output voltage waveform of the secondary winding, along with this, distortion also occurs in the voltage waveform of the auxiliary winding 14 adjacent to the secondary winding. For example, the waveform of the auxiliary winding 14 shown in fig. 9(b) differs from the waveform of the auxiliary winding 14 in the case where the currents flowing through the secondary winding 12 distant from the auxiliary winding 14 and the secondary winding 13 close to the auxiliary winding 14 are 0A and 0.1A, respectively, as shown in fig. 9(a), and the waveforms of the auxiliary winding 14 in the case where the currents flowing through the secondary winding 12 distant from the auxiliary winding 14 and the secondary winding 13 close to the auxiliary winding 14 are 0.1A and 0A, respectively, in the interval of time 260 to 262 μ s, and distortion occurs in the waveform of fig. 9 (b). Since the auxiliary winding 14 is disposed farther from the secondary winding 12 and closer to the secondary winding 13, the coupling coefficients of the auxiliary winding 14 and the secondary windings 12 and 13 are different from each other. Therefore, the magnetic field passing through the auxiliary winding 14 acts differently on the secondary windings 12 and 13, and it is difficult to improve the cross regulation.
On the other hand, in the present embodiment, two auxiliary windings 14 and 16 attached to the core 10 are provided, and these windings 14 and 16 are connected in parallel. Therefore, the auxiliary windings 14, 16 are short-circuited to each other, and the voltage waveforms of the auxiliary windings 14, 16 are the same. For example, fig. 10 shows the voltage waveforms of the auxiliary windings 14 and 16 when the current of the secondary winding 12 is 0A and the current of the secondary winding 13 is 0.1A, and it can be seen that the two waveforms are the same. By providing the auxiliary winding 14 adjacent to the secondary winding 13 and the auxiliary winding 16 adjacent to the secondary winding 12, the magnetic field generated from the auxiliary windings 14 and 16 acts on the adjacent secondary windings 12 and 13.
That is, when the load becomes unbalanced, the voltage waveform of one secondary winding 12, 13 is normal, but distortion occurs in the voltage waveform of the other secondary winding 12, 13. Accordingly, the distorted voltage waveforms of the auxiliary windings 14 and 16 on the secondary windings 12 and 13 side are also distorted. However, the voltage waveforms of the auxiliary windings 14 and 16 on the normal secondary windings 12 and 13 are normal, and the voltage waveforms of the auxiliary windings 14 and 16 on the distorted secondary windings 12 and 13 are also normal because the two auxiliary windings 14 and 16 are short-circuited. The auxiliary windings 14 and 16 having the normal voltage waveform are applied to the secondary windings 12 and 13 having the distorted voltage waveform to have the normal voltage waveform, thereby reducing the distortion. As an example of this, fig. 11 shows voltage waveforms of the secondary windings 12 and 13 before rectification. Fig. 11 shows voltage waveforms when the current in the secondary winding 12 is 0A and the current in the secondary winding 13 is 0.1A. As shown by the circular dotted line in fig. 11, the voltage waveform of the secondary winding 12 has a lower protruding portion (about 20V in the figure) than the protruding portion (about 21V in the figure) of the secondary winding 12 in fig. 8 a, and it is found that distortion is improved. In this way, since the two voltage waveforms of the secondary windings 12 and 13 before rectification are improved to be the same, the cross regulation can be reduced.
(2) In the present embodiment, the secondary windings 12 and 13 are provided on both sides of the primary winding 11 in the direction of the winding axis and closer to the primary winding 11 than the auxiliary windings 14 and 16. This can increase the coupling coefficient between the secondary windings 12 and 13 and the primary winding 11, and can improve the conversion efficiency as a transformer.
[3 ] other embodiments ]
The present invention is not limited to the above embodiments, and includes other embodiments described below. Further, various inventions can be formed by appropriate combinations of a plurality of constituent elements disclosed in the above embodiments and other embodiments described below. The structural elements can be modified and embodied in the implementation stage without departing from the gist thereof. For example, some of the components shown in the embodiments may be deleted, changed, or replaced. The following describes an example of another embodiment. A switching power supply device using a transformer according to the above-described embodiment, another embodiment described below, or a combination thereof is also included in the scope of the present invention.
(1) In embodiments 1 and 2, two secondary windings 12 and 13 are provided, but three or more secondary windings may be provided. In the case where an odd number of secondary windings are provided, for example, in the case where three secondary windings are provided, as shown in fig. 12, two secondary windings 12 and 13 are symmetrically provided with respect to the air gap 15, and the third secondary winding 17 is provided in a layered manner so as to overlap either of the secondary windings 12 and 13. That is, the secondary windings are disposed outside either one of the secondary windings 12 and 13 with the radius centered in the direction of the winding axis changed. However, the windings are insulated from each other by a bobbin made of resin or the like.
In the case where an even number of secondary windings are provided, they are disposed equidistantly from the air gap. When four or more are provided, for example, the layers are overlapped as in the case where an odd number of the layers are provided. In the multi-output type in which three or more secondary windings are provided, as described above, the inductance value and the coupling coefficient with the primary winding 11 can be made equal by making the distance from the primary winding 11 equal to each other while making the symmetry with respect to the air gap 15. Therefore, even in the case of a multi-output, it is possible to obtain a switching power supply device capable of suppressing the mutual deviation of the output voltage values.
(2) In embodiments 1 and 2, the auxiliary windings 14 and 16 and the control circuit 22 are provided so as to be insulated from the primary winding 11, but as shown in fig. 13, the auxiliary windings 14 and 16 and the control circuit 22 may be provided so as to be connected to the primary winding 11. When the control of the switching element 21 is described with reference to fig. 13, the control circuit 22 includes a resistor for dividing the voltage of the auxiliary winding 14, and a voltage monitor unit and an IC for detecting the divided voltage. The IC calculates the output voltages of the secondary windings 12 and 13 based on the input divided voltage value, the divided voltage ratio, and the winding ratio between the auxiliary winding 14 and the secondary windings 12 and 13, generates a control signal so that the control signal becomes a predetermined voltage, and outputs the control signal to the switching element 21.
(3) In embodiment 2, the two auxiliary windings 14 and 16 are provided so that the reels of the windings 11 to 13 are the same and are further away from the primary winding than the secondary windings 12 and 13, but the opposite is also possible. That is, in the direction of each reel, one auxiliary winding 14, 16 may be provided on each side of the primary winding 11, and the secondary windings 12, 13 may be provided on the outside thereof.
(4) In embodiments 1 and 2, the auxiliary windings 14 and 16 are provided on the same straight line so as not to overlap the secondary windings 12 and 13 in the winding direction of the primary winding 11, but may be provided in layers adjacent to the secondary windings 12 and 13 with the radius thereof being changed with respect to the winding direction. In an example, the auxiliary winding 14 may be wound outside the secondary winding 13, and the auxiliary winding 16 may be wound outside the secondary winding 12.
(5) In embodiment 2, the auxiliary windings 14, 16 are disposed equidistant from the air gap 15 and are disposed symmetrically with respect to the air gap 15, but are not limited thereto. That is, even if the auxiliary windings 14 and 16 are provided so as to be non-equidistant and asymmetrical with respect to the air gap 15, they can equally act on the secondary windings 12 and 13. The auxiliary windings 14 and 16 may be provided closer to the primary winding 11 than the secondary windings 12 and 13 in the winding direction.
(6) In embodiment 2, two auxiliary windings 14 and 16 are provided, but three or more auxiliary windings may be provided. For example, when three or more secondary windings are provided, the auxiliary windings are disposed adjacent to the respective secondary windings, and the respective auxiliary windings are connected in parallel with each other.

Claims (3)

1. A transformer, characterized in that the transformer has:
a magnetic core having a straight center leg portion provided at a central portion thereof;
a primary winding mounted on the middle leg portion of the magnetic core and connected to an external power supply;
two or more secondary windings attached to the center leg portion of the core so that the same winding axis as that of the primary winding is provided, the two or more secondary windings being connected to different loads, and power received from the primary winding being connected to the different loads; and
two or more auxiliary windings fitted on the central leg portion of the magnetic core in the same manner as the reels of the primary windings,
wherein the auxiliary windings are provided adjacent to the secondary windings in a direction of a winding axis of each winding, respectively, and the auxiliary windings are electrically connected in parallel with each other,
the auxiliary winding is connected to a control circuit for controlling a switching element electrically connected to the primary winding, the auxiliary winding being supplied with a driving power supply voltage of the control circuit,
the secondary winding is provided on both sides of the primary winding and closer to the primary winding than the auxiliary winding in a direction of a winding axis of the primary winding.
2. The transformer of claim 1,
an air gap is provided in the magnetic core at a portion where the primary winding is mounted,
the secondary winding is disposed on both sides of the primary winding in a direction of a winding axis of the primary winding and at an equal distance from the air gap.
3. A switching power supply device characterized by comprising:
the transformer of claim 1 or 2;
a switching element connected to a primary winding of the transformer; and
and a control circuit for controlling the switching element.
CN201610045872.9A 2015-02-04 2016-01-22 Transformer and switching power supply device Active CN105846679B (en)

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JP6165791B2 (en) * 2015-02-04 2017-07-19 株式会社タムラ製作所 Transformer and switching power supply
CN108320892B (en) * 2018-03-02 2020-09-08 深圳创维－Rgb电子有限公司 Transformer and switching power supply
KR102075417B1 (en) * 2020-01-16 2020-02-10 주식회사 케이피일렉트릭 A main transformer for electric traction vehicle
CN111193408B (en) * 2020-03-04 2024-06-11 深圳英飞源技术有限公司 Mutual feedback type auxiliary power supply circuit

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