KR101665582B1 - Transformer and converter including the same - Google Patents

Abstract

A transformer according to an embodiment of the present invention includes a primary winding, a secondary winding, and a shield winding. The number of turns of the shield winding is determined by the number of windings of the primary winding, the number of windings of the secondary winding, The secondary winding and the parasitic capacitance component of the shield winding.

Description

[0001] TRANSFORMER AND CONVERTER INCLUDING THE SAME [0002]

The present technique relates to a transformer and a converter including the transformer.

Flyback converters are useful in low-cost high-density adapters because they have a simple circuit configuration and fewer elements than other converters. However, since high current and voltage are generated in the switch and the transformer, displacement current is generated, and electromagnetic interference (EMI) is generated by the displacement current. Therefore, a high level of EMI measures is required.

In order to reduce the EMI that may occur in the converter, a method of adding an EMI filter in the converter or increasing the capacity of the capacitor disposed between the winding on the secondary side and the ground is used. However, the addition of the EMI filter affects the price, and the increase of the capacity of the capacitor causes a problem of increasing the leakage current.

Korean Patent Publication No. 10-1318425

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems of the conventional art, and it is an object of the present invention to provide a transformer capable of removing EMI without addition of an EMI filter or a capacitor, and a combter including the transformer.

A transformer according to an embodiment of the present invention includes a primary winding to which input power is applied, a secondary winding formed to be insulated from the primary winding, a shield winding formed between the primary winding and the secondary winding, Wherein the number of windings of the shield winding is determined by the number of windings of the primary winding, the number of windings of the secondary winding, and the parasitic capacitance component of the primary winding, the secondary winding, and the shield winding have.

According to an embodiment of the present invention, EMI can be effectively removed between the primary side and the secondary side of the transformer.

1 is a circuit diagram showing an example of a circuit configuration for reducing EMI of a converter.
2 is an equivalent circuit diagram showing an example of a transformer.
3 is a structural view showing an example of a transformer.
Fig. 4 is an equivalent circuit diagram showing a capacitance component formed between adjacent layers in the transformer shown in Fig. 3. Fig.
5 is an equivalent circuit diagram showing a capacitance component formed across one layer in the transformer shown in Fig.
Fig. 6 is an equivalent circuit diagram showing a capacitance component formed across two layers in the transformer shown in Fig. 3; Fig.
Figure 7 is a diagram provided to illustrate the capacitance component formed across one layer.
Figure 8 is a circuit diagram provided to illustrate the nomenclature of a capacitor.
9 (a) is a circuit diagram showing a converter according to an embodiment of the present invention, and FIG. 9 (b) is a circuit diagram showing a transformer according to an embodiment of the present invention.
10 is an equivalent circuit diagram showing a capacitance component formed in the transformer shown in Fig. 9 (a).
11 is a view for explaining the position of a compensation capacitor according to an embodiment of the present invention.
12 is a simulation graph according to the embodiment of FIG.
13 is a view for explaining the position of a compensation capacitor according to an embodiment of the present invention.
14 is a simulation graph according to the embodiment of FIG.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily carry out the present invention.

1 is a circuit diagram showing an example of a circuit configuration for reducing EMI of a converter. More specifically, FIG. 1 is a circuit for reducing EMI that may occur in a flyback converter using a shield wire.

1 includes a transformer 30 including a filter portion 10, a rectifying portion 20, a primary winding N _p , a secondary winding N _s and a shield winding N _sh , a switch 40, , And a reduction capacitor (50).

The filter unit 10 is connected to a power supply terminal to which the AC power source AC is applied, so that the noise mixed in the AC power source AC can be removed. The filter unit 10 may include a line filter, and the filter unit 10 may operate as a kind of low-pass filter.

The rectifying unit 20 rectifies the power received from the filter unit 10 and can transmit power to the primary winding N _p disposed on the primary side of the transformer 30. Power applied to the primary winding of the transformer 30 can be transmitted to the secondary winding (N _s) disposed on the secondary side of the transformer 30 in accordance with the switching operation of the switch 40. At this time, the primary winding Np and the secondary winding Ns can be electromagnetically coupled or inductively coupled.

In Fig. 1, the voltage V _p is a path of noise generated on the primary side, the voltage V _s is a path of noise generated on the secondary side, and the voltage V _sh is a path of noise generated on the shield winding N _sh . Referring to FIG. 1, the shield winding N _sh forms a path of noise in a path opposite to the path of noise generated in the primary side and the secondary side, thereby reducing the noise generated in the primary side and the secondary side.

The reduction capacitor 50 is disposed on the secondary side and the ground side, and the noise generated in the primary side and the secondary side can be attenuated. At this time, the capacitance of the reduced capacitor 50 is proportional to the magnitude of the noise generated at the primary side and the secondary side. When the noise is large, the capacitance of the reduced capacitor 50 also increases, There is a problem in that it becomes larger and becomes bulky.

According to one embodiment of the present invention, by adjusting the winding of the shield winding of the transformer, or connecting at least two of the primary winding, the secondary winding, and the shield winding to the compensation capacitor, EMI Can be removed.

2 is an equivalent circuit diagram showing an example of a transformer. 2, an equivalent circuit of a transformer may include a first winding Np formed between nodes A and B and a second winding Ns formed between nodes C and D. At this time, the first winding Np and the second winding Ns are insulated from each other and can be coupled to each other electromagnetically. It also includes a plurality of capacitors C1-C6 according to the electromagnetic coupling of the first winding Np and the second winding Ns or the parasitic capacitance component of each of the first winding Np and the second winding Ns can do.

Specifically, the capacitor C1 is connected between nodes A and C, the capacitor C2 is connected between nodes C and B, the capacitor C3 is connected between nodes A and D, the capacitor C4 is connected between nodes B and D, the capacitor C5 is connected between nodes A and B A capacitor C6 may be formed between nodes C and D.

The capacitances of the plurality of capacitors in FIG. 2 can be expressed by the following Equation (1). At this time, C ₀ represents the capacitance measured between the primary side and the secondary side.

3 is a structural view showing an example of a transformer. Specifically, Figure 3 shows the structure of a transformer that may be employed in a flyback converter. In Fig. 3, Lc represents the center leg of the core of the transformer and Lo represents the outer leg of the nose of the transformer. The windings Np1 and Np2 represent primary windings and may be configured in parallel interleaved form, the winding Np1 may be formed in the outer leg Lc, and the winding Np2 may be formed in the middle leg Lo. The winding Ns represents the secondary winding, and the windings Nsh1 and Nsh2 represent the shield winding. Each winding may be composed of a single layer. The winding Np1 is connected to the first layer L1, the winding Nsh1 to the second layer L2, the winding Ns to the third layer L3, and the winding Nsh2 to the fourth layer L4, and the winding Np2 may be sequentially formed on the fifth layer L5. The terminals shown on one side of each winding represent the physical positions of the dots of the transformer, and U and D of each layer (L1-L5) represent both ends of each layer.

The primary windings N _p1 and N _p2 may have opposite dot polarities to the secondary windings N _s1 and N _s2 and the shield windings N _sh1 and N _sh2 may be connected to the primary windings N _p1 and N _p2 And the dot polarity of one of the secondary windings N _s1 and N _s2 . In one example, the shield windings N _sh1 and N _sh2 may have the same dot polarity as the secondary windings N _s1 and N _s2 .

When the principle of the equivalent circuit of the transformer as shown in Fig. 2 is applied to the structure of the transformer of Fig. 3, it can be represented as the circuit shown in Figs. 4 to 6.

4 is an equivalent circuit diagram showing a capacitance component formed between adjacent layers, FIG. 5 is an equivalent circuit diagram showing a capacitance component formed across one layer, and FIG. 6 is a diagram showing a capacitance component formed across two layers An equivalent circuit diagram.

The capacitance component formed between the adjacent layers can be measured after disconnecting both ends of the corresponding layers, but the component of the capacitor formed across one or two layers can be measured using the following method.

Figure 7 is a diagram provided to illustrate the capacitance component formed across one layer.

The capacitance component measured between the A layer and the C layer includes the capacitance component related to the B layer. Therefore, in order to remove the capacitance component related to the B layer, the capacitance component C ₃ between the A layer and the C layer can be expressed by the following equation (2).

Where C ₁ is the capacitance measured between the A and B layers, C ₂ is the capacitance measured between the B and C layers, and C _3e is the capacitance measured between the A and C layers.

Figure 8 is a circuit diagram provided to illustrate the nomenclature of capacitors to be used in the following description. The names of the capacitors can be determined according to the layer to be formed and the order. For example, as illustrated, the capacitor according to the capacitance component formed on the X layer and Y layer may be referred to as a C _XY, for the first capacitor, such as C _{XY _1,} the second case the capacitor C _{XY _2} . ≪ / RTI >

9 (a) is a circuit diagram showing a converter according to an embodiment of the present invention, and FIG. 9 (b) is a circuit diagram showing a transformer according to an embodiment of the present invention. 9A, a converter according to an embodiment of the present invention may include a filter unit 100, a rectifier unit 200, a transformer 300, and a switch 400 reduction capacitor 500. The converter shown in Fig. 9A is a flyback converter similar to the converter described in Fig. 1, and therefore, the transformer shown in Fig. 9B will be mainly described below.

9 (b), the transformer 300 may include a primary winding N _p , a secondary winding N _s, and first and second shield windings N _sh1 and N _sh2 . The primary winding Np of the transformer It is assumed that EMI power source (EMI source) is connected at one end to provide EMI generated according to the operation of the converter.

When the principle of the equivalent circuit of the transformer as shown in Figs. 4 to 6 is applied to the transformer of Fig. 9 (b), the transformer of Fig. 9 (b) can be represented as the circuit shown in Fig.

However, in this case, the leakage inductance of the transformer and the resonance of the parasitic capacitor of the switch are out of the range of maintaining the characteristics of the transformer, and therefore, the DC voltage can not be applied to the transformer in a steady state. Do not.

Since the leakage inductance of the transformer is ignored in FIG. 10, the voltage applied to each winding can be determined according to the voltage of the applied EMI power source and the number of windings of each winding. The voltage V _{p corresponds} to the primary winding N _p , the voltage V _{s corresponds} to the secondary winding N _s , and the voltages V _sh1 and V _sh2 correspond to the voltages applied to the shield windings N _sh1 and N _sh2 .

The current generated by the voltages V _p , V _s , V _sh1 and V _sh2 can be calculated by the principle of superposition. By using the capacitance of the reduction capacitor 500 of FIG. 9 (a) the both-end voltage V _{Y -} can be calculated by equation (3) to the _cap.

Referring to Equation 3, the both-end voltage V _Y of the reduction capacitor ₍₅₀₀₎ there can be derived a number of turns of the shield winding to reduce the _cap, like the number of windings of the first and second shield winding (N _sh1, N _sh2) , The winding N _sh of the first and second shield windings N _sh1 and N _sh2 can be derived according to the following equation (4).

The number N _sh of windings of the shield winding N _sh represents the number of windings N _p of the primary winding, the number of windings N _{s of the} secondary winding, and the parasitic capacitance component of the primary winding, the secondary winding, and the shield winding C _p , C _s , C _sh1 , and C _sh2 .

Referring to Equation (3), the capacitance component C _p corresponds to the sum of the capacitance component between the first primary winding and the secondary winding, the capacitance component of the secondary winding and the second primary winding, and the capacitance component C _s is a capacitance component between the first primary winding and the secondary winding, a capacitance component between the first shield winding and the secondary winding, a capacitance component between the secondary winding and the second shield winding, and a capacitance between the secondary winding and the second primary winding The capacitance component C _sh1 corresponds to the sum of the capacitance components of the first shield winding and the secondary winding and the capacitance component C _sh2 corresponds to the sum of the capacitance components of the secondary winding and the second shield winding .

However, since the number of windings N _sh of the shield winding calculated according to Equation (4) may not be calculated as an integer, EMI may not be completely removed. At this time, the compensation capacitor to add a C _comp, a voltage V is applied to the _Y reduction capacitor ₍₅₀₀₎ may reduce the size of the _cap.

When the voltage V _{Y - cap} of the reduced capacitor 500 is negative, the compensation capacitors C _comp are connected in parallel to the capacitors related to the capacitances C _p and C _s as shown in Equations (5) and (6) Can be reduced.

In addition, the reduced voltage V _Y of the capacitor ₍₅₀₀₎ by connecting a capacitance C _sh1 and C _sh2 the compensation capacitor C _comp the associated capacitor as _cap (7) and (8) below appears as a positive value in parallel, reducing the capacitor It is possible to reduce the magnitude of the voltage applied to the transistor 500.

11 is a view for explaining the position of a compensation capacitor according to an embodiment of the present invention.

Referring to Fig. 11, a compensation capacitor C _comp may be disposed between the first shield winding N _sh1 and the secondary winding N _s . More specifically, the compensation capacitor C _comp can connect the dot side portion of the first shield winding N _sh1 and the non-dot side portion of the secondary winding N _s .

12 is a simulation graph according to the embodiment of FIG. FIG. 12A is a graph of the voltage of the reduction capacitor 500 when the compensation capacitor C _comp is not provided, and FIG. 12B is a graph of the reduction capacitor 500 when the compensation capacitor C _comp is provided.

12A and 12B, when the compensation capacitor C _comp is not provided, the oscillation voltage of the reduction capacitor 500 is 1.95 V, but when the compensation capacitor C _comp is provided, The oscillation voltage of the reduction capacitor 500 is 0.2 V, and the voltage of the reduction capacitor 500 is decreased.

13 is a view for explaining the position of a compensation capacitor according to another embodiment of the present invention.

Referring to Fig. 13 (a), the compensation capacitor C _comp can be disposed between the first shield winding N _sh1 and the secondary winding N _s . More specifically, the compensation capacitor C _comp can connect the portion on the dot side of the first shield winding N _sh1 and the portion on the dot side of the secondary winding Ns.

13 (b), the compensation capacitor C _comp can be disposed between the first primary winding N _p1 and the secondary winding N _s . More specifically, the compensation capacitor C _comp can connect the dot-side portion of the first primary winding N _{p1 and} the dot-side portion of the secondary winding Ns.

14 is a simulation graph according to the embodiment of FIG. FIG. 14A is a graph of the voltage of the reduction capacitor 500 when the compensation capacitor C _comp is not provided, and FIG. 14B is a graph of the reduction capacitor 500 when the compensation capacitor C _comp is provided.

14A and 14B, when the compensation capacitor C _comp is not provided, the oscillation voltage of the reduction capacitor 500 is 1.73 V, but when the compensation capacitor C _comp is provided, 500 is 0.51V, it can be seen that the voltage of the reduction capacitor 500 is reduced.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, Those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Therefore, the spirit of the present invention should not be construed as being limited to the above-described embodiments, and all of the equivalents or equivalents of the claims, as well as the following claims, I will say.

100:
200: rectification part
300: Transformer
400: Switch
500: Reduced Capacitor

Claims (16)

A primary winding, a secondary winding, and a shield winding,
The number of windings of the shield winding is determined by the number of windings of the primary winding, the number of windings of the secondary winding, and the parasitic capacitance component of the primary winding, the secondary winding, and the shield winding,
Wherein the number of windings of the shield winding is inversely proportional to a sum of capacitance components of the shield winding and the secondary winding.
The method according to claim 1,
Said primary winding comprising a first primary winding and a second primary winding,
Wherein the shield winding includes a first shield winding and a second shield winding,
Wherein the first primary winding, the first shield winding, the secondary winding, the second shield winding, and the second primary winding are sequentially arranged in a single layer.
The shield according to claim 2, wherein the number of turns of the shield winding
A transformer determined by the following equation.
[Equation]

(N _{sh is the} number of windings of the shield winding, N _{p is the} number of windings of the primary winding, N _{s is the} number of windings of the secondary winding, C _p is the capacitance component between the primary windings and the secondary windings, C _s : a capacitance component between the first primary winding and the secondary winding, a capacitance component between the first shield winding and the secondary winding, a secondary winding and a second shield winding C _sh1 is the sum of the capacitance components of the first shield winding and the secondary winding, C _sh2 is the sum of the capacitance of the secondary winding and the second shield winding, C _sh2 is the sum of the capacitance components of the primary winding and the secondary winding, Sum of ingredients) 3. The method of claim 2,
Wherein the primary winding and the secondary winding have opposite dot polarities.
5. The method of claim 4,
Wherein the shield winding has the same dot polarity as one of the primary winding and the secondary winding.
6. The shield according to claim 5,
And the polarity of the dot is the same as that of the secondary winding.
The method according to claim 6,
A compensation capacitor coupling the at least one of the first shield winding and the second shield winding to the secondary winding; ≪ / RTI >
8. The apparatus of claim 7, wherein the compensation capacitor comprises:
And a shield winding and a portion of the secondary winding having the same dot polarity.
8. The apparatus of claim 7, wherein the compensation capacitor comprises:
And a shield winding and a portion of the secondary winding whose dot polarities are opposite to each other.
The method according to claim 1,
Wherein the primary winding includes a first primary winding wound around an intermediate leg of the core and a second primary winding wound on an intermediate leg outside of the first primary winding, A first shield winding and a second shield winding wound inside the primary winding and the second primary winding respectively adjacent to the first primary winding and the second primary winding,
And the secondary winding is wound between the first shield winding and the second shield winding.
A transformer including a primary winding to which an input power is applied and a secondary winding insulated from the primary winding, a shield winding formed between the primary winding and the secondary winding, and the secondary winding;
A switch connected to the primary winding to switch a power source applied to the primary winding; And
A reduction capacitor connected to the secondary winding to attenuate a displacement current formed between the primary winding and the secondary winding; Lt; / RTI >
Wherein the transformer further comprises a compensation capacitor coupling the two windings of the primary winding, the secondary winding and the shield winding according to the polarity of the voltage applied to the reduction capacitor.
12. The method of claim 11,
Wherein the number of windings of the shield winding is determined by the number of windings of the primary winding, the number of windings of the secondary winding, and the parasitic capacitance component of the primary winding, the secondary winding, and the shield winding.
12. The method of claim 11,
Wherein the primary winding and the secondary winding have opposite dot polarities.
12. The method of claim 11,
Wherein the shield winding has the same dot polarity as one of the primary winding and the secondary winding.
12. The shielding apparatus according to claim 11,
And the dot polarity is the same as the polarity of the secondary winding.
12. The method of claim 11,
Said primary winding comprising a first primary winding and a second primary winding,
Wherein the shield winding includes a first shield winding and a second shield winding,
Wherein the first primary winding, the first shield winding, the secondary winding, the second shield winding, and the second primary winding are sequentially arranged in a single layer.

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