Current transformer for high-frequency switching power supply

Abstract

The utility model relates to the technical field of electronic components, in particular to a current transformer for a high-frequency switching power supply, which comprises a magnetic core, a primary coil, a secondary coil, an inner shell and an outer shell, the primary coil is wound on the magnetic core to form a primary winding, and the secondary coil penetrates through the magnetic core to form a secondary winding. The magnetic core and the primary coil are arranged in the inner shell, the secondary coil penetrates through the center of the inner shell, the inner shell is arranged in the outer shell, and the periphery of the outer shell is provided with a peripheral layer for shielding and / or insulation. Compared with a current transformer in the prior art, the current transformer provided by the utility model has the advantages that the double-shell design of the inner shell and the outer shell is adopted, and meanwhile, the peripheral layer for shielding and insulating is arranged on the periphery, so that the current transformer is high in anti-interference capability, good in stability and good in current sampling detection effect at a high frequency band.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic components technical field especially relates to a current transformer for high frequency switching power supply. BACKGROUND

[0002] In high frequency switching power supply, the current of switch tube, inductor and other components needs to be detected to provide for control protection circuit. The current detection method usually has hall element, resistance or current transformer sampling.

[0003] The hall element sampling has isolation between control and main power circuit, can detect direct current signal, and signal restoration is good, but has microsecond level delay, and the price is relatively expensive. The resistance direct sampling is very cheap, and signal restoration is good, but control circuit and main power circuit are not isolated, and power consumption is relatively large. The current transformer sampling has the advantages of low energy consumption, wide frequency band, good signal restoration, low price, isolation between control and main power circuit, etc.

[0004] At present, the current transformer for high frequency switching power supply on the market mainly includes a magnetic core, a primary coil and a secondary coil, the primary coil is wound on the magnetic core to form a primary winding, the secondary coil passes through the magnetic core to form a secondary winding, and the periphery is simply wrapped with insulating tape. The current transformer with the above structure has poor effect at high frequency band, is easily affected by electromagnetic interference of other elements in the switching power supply, and has not ideal detection effect in the circuit. UTILITY MODEL CONTENTS

[0005] The utility model aims at the shortage of prior art and provides a current transformer for high frequency switching power supply, which has strong anti-interference ability, good stability and good current sampling detection effect at high frequency band.

[0006] The utility model achieves the purpose by the following technical measures:

[0007] A current transformer for high frequency switching power supply includes a magnetic core, a primary coil and a secondary coil, the primary coil is wound on the magnetic core to form a primary winding, the secondary coil passes through the magnetic core to form a secondary winding, and the current transformer further includes an inner shell and an outer shell, the magnetic core and the primary coil are arranged in the inner shell, the secondary coil is arranged at the center of the inner shell, the inner shell is arranged in the outer shell, and the outer shell is provided with a peripheral layer for shielding and / or insulation.

[0008] Further, the magnetic core is a ring-shaped magnetic core, and the primary coil is wound on the magnetic core by a quarter of the butterfly winding method.

[0009] Further, the magnetic core is made of manganese-zinc material, the primary coil is made of enameled wire with a diameter of 0.05-0.15 mm, and the primary coil is wound on one fourth of the magnetic core for three layers, and then the winding of the other four fourths of the magnetic core is sequentially completed one by one.

[0010] Further, the shell includes a shell horizontal end face, a shell side wall, a shell annular cavity, and a shell cylinder provided at the center of the shell annular cavity, wherein the shell cylinder is provided with a shell through hole for the secondary coil to pass through; the inner shell includes an inner shell horizontal end face, an inner shell side wall, an inner shell annular cavity, and an inner shell cylinder provided at the center of the inner shell annular cavity, wherein the primary winding is arranged in the inner shell annular cavity, the inner shell cylinder is sleeved with the primary winding, and the inner shell cylinder is provided with an inner shell through hole for the shell cylinder to be sleeved; and the inner shell is invertedly buckled on the shell, wherein the outer side of the inner shell side wall abuts against the inner side of the shell side wall, and the shell cylinder is sleeved in the inner shell through hole.

[0011] Further, the inner shell is filled with potting glue.

[0012] Further, the peripheral layer includes an inner layer insulating tape on the inner side, a shielding layer in the middle, and an inner layer insulating tape on the outer side; and the shielding layer is made of silver, copper or aluminum.

[0013] Further, the current transformer further includes a bottom plate, a head portion of the shell is provided with a vertical face, the bottom plate is tightly attached to the vertical face, and two ends of the secondary coil are provided with pins, and the bottom plate is provided with a hole position, and the pins pass through the hole position of the bottom plate and are fixed.

[0014] Further, two ends of the primary coil are provided with lead wires, a tail portion of the inner shell is provided with an inner shell extension cavity for placing the lead wires, a tail end of the inner shell extension cavity is provided with clamping grooves for the two lead wires to pass through, a tail portion of the shell is correspondingly provided with a shell extension cavity for placing the inner shell extension cavity, and a tail end of the shell extension cavity is also provided with a corresponding groove position.

[0015] Further, the lead wires are peripherally wrapped with insulating sleeves, and end portions of the lead wires are provided with plug-in terminals.

[0016] Further, the plug-in terminal is a copper terminal, and the copper terminal is provided with a barb.

[0017] The utility model has the advantages that:

[0018] The utility model discloses a current transformer, including magnetic core, primary coil, secondary coil, the primary coil is wound in the magnetic core and forms primary winding, the secondary coil passes through the magnetic core and forms secondary winding, and the current transformer still includes inner shell, shell, the magnetic core, primary coil all are placed in the inner shell, and the secondary coil is worn in the center of inner shell, and the inner shell is placed in the shell, and the periphery of shell is provided with the peripheral layer for shielding and / or insulation. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 It is the three-dimensional exploded structure schematic diagram of the utility model;

[0020] Figure 2 It is Figure 1 The enlarged structure schematic diagram of A place in the middle;

[0021] Figure 3 It is the three-dimensional structure schematic diagram of the back direction of inner shell of the utility model;

[0022] Figure 4 It is the cross section winding structure schematic diagram of the magnetic core and primary coil in horizontal direction of the utility model.

[0023] The serial number of drawing is as follows:

[0024] Primary winding 100,

[0025] Magnetic core 1,

[0026] Primary coil 2, lead wire 21, insulating sleeve 22, plug-in terminal 23, barb 24, wire starting direction 201, wire winding direction 202,

[0027] Secondary coil 3, pin 31,

[0028] Inner shell 4, inner shell annular cavity 41, inner shell cylinder 42, inner shell through-hole 43, inner shell extension cavity 44, clamping groove 45,

[0029] Shell 5, shell annular cavity 51, shell cylinder 52, shell through-hole 53, vertical surface 54, shell extension cavity 55, slot 56,

[0030] Peripheral layer 6, inner layer insulating tape 61, shielding layer 62, outer layer insulating tape 63,

[0031] Potting adhesive 7,

[0032] Bottom plate 8. DETAILED DESCRIPTION

[0033] In order to describe the technical scheme of the utility model in detail, the technical scheme of the utility model embodiment will be described clearly and completely in combination with the drawings of the utility model embodiment. Obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments. Based on the described embodiment of the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model.

[0034] Please refer to Figures 1 to 4 The current transformer of the utility model, comprising a magnetic core 1, a primary coil 2, a secondary coil 3, the primary coil 2 is wound on the magnetic core 1 to form a primary winding 100, and the secondary coil 3 passes through the magnetic core 1 to form a secondary winding. Wherein, the current transformer of the utility model further comprises an inner shell 4 and an outer shell 5. The magnetic core 1 and the primary coil 2 are both placed in the inner shell 4, so that the inner shell 4 can protect and isolate the magnetic core 1 and the primary coil 2. The secondary coil 3 is arranged in the center of the inner shell 4, and the inner shell 4 is placed in the outer shell 5, so that the outer shell 5 has a further protection and isolation effect, increasing the safety distance. The outer shell 5 is provided with a peripheral layer 6 for shielding and / or insulation, preferably, as shown in Figure 1 The peripheral layer 6 comprises an inner layer insulation tape 61 on the inner side, a shielding layer 62 in the middle and an outer layer insulation tape 63 on the outer side. The shielding layer 62 is made of silver, copper or aluminum. This multi-layer shielding and insulation structure can effectively isolate external electromagnetic interference, prevent internal electromagnetic field leakage and significantly improve the anti-interference ability and electromagnetic compatibility of the current transformer of the utility model, while providing good insulation performance.

[0035] Therefore, the current transformer of the utility model adopts a double-shell design of inner shell and outer shell, and is provided with a peripheral layer for shielding and insulation on the periphery, so that the current transformer of the utility model has strong anti-interference ability, good stability and good current sampling detection effect at high frequency.

[0036] Preferably, as shown in Figure 4 The magnetic core 1 is a ring-shaped magnetic core, and the primary coil 2 is wound on the magnetic core 1 by a quarter of the butterfly winding method. The quarter of the butterfly winding method can make the frequency band of the current transformer of the utility model wider. More specifically, the magnetic core 1 is made of manganese-zinc material, the primary coil 2 is made of enameled wire with a diameter of 0.05-0.15mm, and the primary coil 2 is wound on the four quarters of the magnetic core 1 in turn, preferably, as shown in Figure 4The primary coil 2 is wound from the start winding direction 201 to the end winding direction 202 (the number of coils in the figure is only for reference), and the arrow direction indicates the winding direction.

[0037] Preferably, as shown in the figure, Figure 1 The shell 5 includes a shell horizontal end face, a shell side wall, and a shell annular cavity 51, and the shell annular cavity 51 is provided with a shell cylinder 52 in the center, and the shell cylinder 52 is provided with a shell through hole 53 for the secondary coil to pass through. Figure 1 and Figure 3 The inner shell 4 includes an inner shell horizontal end face, an inner shell side wall, and an inner shell annular cavity 41, and the primary winding 100 is arranged in the inner shell annular cavity 41, and the inner shell annular cavity 41 is provided with an inner shell cylinder 42 in the center, and the primary winding 100 is sleeved on the inner shell cylinder 42, and the inner shell cylinder 42 is provided with an inner shell through hole 43 for the shell cylinder 52 to be sleeved in. The inner shell 4 is invertedly buckled on the shell 5, wherein the outer side of the inner shell side wall abuts against the inner side of the shell side wall, and the shell cylinder 52 is sleeved in the inner shell through hole 43. The above-mentioned ingenious design of the inner shell 4 and the shell 5 can further enhance the stability of the current transformer of the utility model, increase the safety distance from other electronic components, can withstand a high voltage of up to 4500V, and can meet the fireproof level of UL94-V0.

[0038] Preferably, as shown in the figure, Figure 1 The inner shell 4 is filled with potting glue 7, and the magnetic core 1 and the primary coil 2 can be potted, so that the insulation performance can be further improved, the gaps between the windings can be effectively filled, the air gap can be reduced, the thermal resistance can be reduced, and the heat dissipation performance can be improved.

[0039] Preferably, as shown in the figure, Figure 1 The current transformer of the utility model further includes a bottom plate 8, the head of the shell 5 is provided with a vertical face 54, and the bottom plate 8 is tightly attached to the vertical face 54. The two ends of the secondary coil 3 are provided with pins 31, and the bottom plate 8 is provided with a hole position, and the pins 31 pass through the hole position of the bottom plate 8 and are fixed. This design not only facilitates installation and fixation, but also ensures stable and reliable electrical connection of the secondary coil, and further improves the overall performance of the current transformer.

[0040] Preferably, as shown in the figure, Figures 1 to 3As shown, two ends of the primary coil 2 are provided with lead wires 21, and the tail of the inner shell 4 is provided with an inner shell extension cavity 44 for placing the lead wires, and the tail end of the inner shell extension cavity 44 is provided with a clamping groove 45 for passing the two lead wires 21; and the tail of the outer shell 5 is correspondingly provided with an outer shell extension cavity 55 for placing the inner shell extension cavity 44, and the tail end of the outer shell extension cavity 55 is also provided with a corresponding slot 56; such a structure design not only facilitates the arrangement and fixation of the lead wires, but also further improves the overall structural compactness and reliability of the current transformer. Further, the periphery of the lead wire 21 is wrapped with an insulating sleeve 22, and the end of the lead wire 21 is provided with a plug-in terminal 23; the plug-in terminal 23 is a copper terminal provided with a barb 24; such a design not only ensures the electrical insulation performance of the lead wire, but also realizes reliable electrical connection through the barb structure of the copper terminal, preventing the lead wire from loosening or falling off under high-frequency working conditions; especially when the plug-in terminal needs to be welded to the PCB board, the copper terminal provided with the barb can be inserted into the welding hole of the PCB board and is not easy to pop up, thereby increasing the welding reliability.

[0041] The production process of the current transformer of the utility model is as follows: firstly, the primary coil is wound on the magnetic core through a quarter butterfly winding method; then, the magnetic core with the wound primary coil is sleeved into the cylinder of the inner shell and placed in the annular cavity of the inner shell; then, the annular cavity of the inner shell is injected with potting glue; then, the inner shell with the injected potting glue is reversely clamped in the outer shell, so that the cylinder of the outer shell is sleeved into the through hole of the inner shell and the inner shell is placed in the annular cavity of the outer shell; then, the secondary coil (usually a wire) is passed through the through hole of the outer shell, and the pins at both ends of the secondary coil are fixed through the hole positions of the bottom plate; finally, the periphery of the outer shell is wound with an insulating layer and a shielding layer, and the periphery of the lead wire is sleeved with an insulating sleeve.

[0042] Through tests, the current transformer of the utility model and the commonly used current transformer are compared in terms of inductance in each frequency band, as shown in the following table:

[0043]

[0044] As shown in the above table, the inductance of the commonly used current transformer starts to decrease at a frequency of 200K, and the inductance at a frequency of 400K is zero, while the inductance of the current transformer of the utility model remains relatively stable before a frequency of 300K, and there is still inductance at frequencies of 400K and 500K.

[0045] In summary, the current transformer of the utility model exhibits excellent performance in high-frequency switching power supplies, can effectively improve the conversion efficiency, stability and reliability of the power supply, reduce electromagnetic interference and improve electromagnetic compatibility, and is suitable for various application scenarios of high-frequency switching power supplies.

[0046] The above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently, and still fall within the protection scope of the present application.

Claims

1. A current transformer for high frequency switching power supply, comprising a magnetic core, a primary coil and a secondary coil, the primary coil is wound around the magnetic core to form a primary winding, the secondary coil passes through the magnetic core to form a secondary winding, characterized in that: The transformer further comprises an inner shell and an outer shell, the magnetic core and the primary coil are arranged in the inner shell, the secondary coil is arranged in the center of the inner shell, the inner shell is arranged in the outer shell, and a peripheral layer is arranged on the periphery of the outer shell for shielding and / or insulation.

2. The current transformer for high frequency switching power supply according to claim 1, characterized in that: The magnetic core is a ring-shaped magnetic core, and the primary coil is wound on the magnetic core by a quarter butterfly winding method.

3. A current transformer for use in a high frequency switching power supply according to claim 2, characterized in that: The magnetic core is made of manganese-zinc material, the primary coil is made of enameled wire with a diameter of 0.05-0.15 mm, and the primary coil is wound on three layers of the quarter of the magnetic core, and then the winding of the other four quarters of the magnetic core is sequentially completed one by one.

4. The current transformer for high frequency switching power supply according to any one of claims 1 to 3, characterized in that: The outer shell comprises an outer shell horizontal end face, an outer shell side wall, and an outer shell ring-shaped cavity, and a cylindrical outer shell is arranged in the center of the outer shell ring-shaped cavity, and the cylindrical outer shell is provided with an outer shell through hole for the secondary coil to pass through. The inner shell comprises an inner shell horizontal end face, an inner shell side wall, and an inner shell ring-shaped cavity, and the primary winding is arranged in the inner shell ring-shaped cavity, and a cylindrical inner shell is arranged in the center of the inner shell ring-shaped cavity, and the cylindrical inner shell is provided with an inner shell through hole for the cylindrical outer shell to be sleeved into. The inner shell is invertedly buckled on the outer shell, wherein the outer side of the inner shell side wall abuts against the inner side of the outer shell side wall, and the cylindrical outer shell is sleeved into the inner shell through hole.

5. A current transformer for use in a high frequency switching power supply as claimed in claim 4, characterized in that: The inner shell is filled with potting glue.

6. The current transformer for use in a high frequency switching power supply according to claim 1, characterized by: The peripheral layer comprises an inner layer insulation tape on the inner side, a shielding layer in the middle, and an inner layer insulation tape on the outer side; and the shielding layer is made of silver, copper or aluminum.

7. The current transformer for use in a high frequency switching power supply according to claim 1, characterized in that: The transformer further comprises a bottom plate, a head portion of the outer shell is provided with a vertical face, and the bottom plate is tightly attached to the vertical face; both ends of the secondary coil are provided with pins, and the bottom plate is provided with a hole position, and the pins pass through the hole position of the bottom plate and are fixed.

8. The current transformer for use in a high frequency switching power supply according to claim 1, characterized by: Both ends of the primary coil are provided with lead wires, a tail portion of the inner shell is provided with an inner shell extension cavity for placing the lead wires, and a tail end of the inner shell extension cavity is provided with a clamping groove for the two lead wires to pass through; a tail portion of the outer shell is correspondingly provided with an outer shell extension cavity for placing the inner shell extension cavity, and a tail end of the outer shell extension cavity is also provided with a corresponding groove position.

9. A current transformer for use in a high frequency switching power supply as claimed in claim 8, characterized in that: The periphery of the lead wire is wrapped with an insulation sleeve, and the end portion of the lead wire is provided with a plug-in terminal.

10. A current transformer for use in a high frequency switching power supply as claimed in claim 9, characterized in that: The plug-in terminal is a copper terminal provided with a barb.

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