TWM471017U - Transformer used in inverse switch power source - Google Patents

Description

Transformer used in flyback switching power supplies

This creation relates to the field of circuits, and more particularly to a transformer for use in a flyback switching power supply.

The charger is a must-have part of many portable electronic devices such as mobile phones. A charger that supplies power to a portable electronic device such as a capacitive touch screen smart phone with a touch screen must meet the following two conditions: 1) Common Mode Noise (Common Mode Noise) Reduced to less than 2 volts; 2) meet the requirements of Conducted Susceptibility (CS) for portable electronic devices. The above two conditions that the charger needs to meet put forward higher requirements for the key component "transformer" in the charger. How to effectively reduce common mode noise and conducted immunity while solving electromagnetic-magnetic interference (EMI) is the key to whether the chargers produced by various power supply manufacturers have market competitiveness. How to further simplify the winding process of the transformer used in the charger and save the winding time while solving the problems of EMI, Common Mode Noise and CS has become an urgent problem to be solved in the field of switching power supply.

In view of one or more of the problems described above, the present application provides a transformer for use in a flyback switching power supply.

A transformer for use in a flyback switching power supply according to an embodiment of the present invention includes a bobbin, a magnetic core, a primary winding, a secondary winding, a chip auxiliary power supply winding, a mask winding, and an insulating tape, wherein: primary winding, vice The side windings, the chip auxiliary power supply windings, and the mask windings are wound in the following order: primary winding → wafer auxiliary power winding → mask winding → secondary winding; wafer auxiliary power supply winding is wound with single or double wires And the skeletal width occupied by it is 1/2 to 3/4 of the entire width of the skeleton; the cover winding is made of a copper cover, in which the copper is Length of 0.6 to 0.9 turns, one end of the enameled wire is connected to the copper skin, and the other end is connected to the grounding leg on the primary side of the skeleton; the primary winding, the secondary winding, the chip auxiliary power supply winding, and the windings in the shield winding There are 1 to 8 layers of insulating tape between them; the primary winding is made of a single wire wound three layers, and the middle winding is not wound with insulating tape; the secondary winding is made of triple insulated wire, and It is located at the outermost layer with respect to the primary winding, the wafer auxiliary power supply winding, and the shield winding.

This creation considers the consistency of the mass production performance consistency of the product, reduces the number of winding processes of the transformer used in the flyback switching power supply, greatly improves the production efficiency of the transformer, and reduces the production cost of the transformer. . In addition, the transformer used in the flyback switching power supply according to the present invention can pass EMI test, Common Mode Noise, CS test and other safety specification tests.

1‧‧‧AC rectifier circuit

2‧‧‧EMI filter circuit

3‧‧‧Absorption circuit

4‧‧‧Feedback circuit

5‧‧‧ flyback switching circuit

6‧‧‧Output rectification filter circuit

7‧‧‧Control circuit

80‧‧‧Fuse (FUSE)

81‧‧‧Drain

82‧‧‧DC power bus (Buck)

83‧‧‧ wafer auxiliary power supply winding (VDD winding)

84‧‧‧ Grounding (GND)

Q1‧‧‧Switch tube

85‧‧‧ Copper (Copper)

86‧‧‧Signal output pin (VDD)

Fig. 1 is a view showing a typical circuit diagram of a flyback switching power supply to which a transformer used in a flyback switching power supply according to an embodiment of the present invention is applied.

2A and 2B are block diagrams showing the winding structure of a transformer used in a flyback switching power supply according to an embodiment of the present invention, in which black dots indicate winding points.

Features and exemplary embodiments of various aspects of the present work are described in detail below. The following description covers many specific details to provide a thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely provided to provide a clearer understanding of the present invention by the example of the present invention. The present invention is in no way limited to any specific configuration as set forth below, but without departing from the spirit of the present invention, any modification, substitution, or modification of the related elements or components.

Fig. 1 is a view showing a typical circuit diagram of a flyback switching power supply to which a transformer used in a flyback switching power supply according to an embodiment of the present invention is applied. As shown in Figure 1, the flyback The switching power supply includes an AC rectification circuit 1, an EMI filter circuit 2, an absorption circuit 3, a feedback circuit 4, a flyback switch circuit 5, an output rectification filter circuit 6, and a control circuit 7. among them:

The AC rectifying circuit 1 includes a fuse (FUSE) 80 and a rectifying diode, and the main function of the AC rectifying circuit 1 is to rectify the AC voltage.

The EMI filter circuit 2 includes an inductor, a high voltage electrolytic capacitor, and an Electro-Static Discharge resistor, and the main function of the EMI filter circuit 2 is to suppress EMI and post-rectification filtering.

The absorbing circuit 3 includes a capacitor, a resistor, and a diode (the configuration of the absorbing circuit can be varied according to different system requirements), and the main function of the absorbing circuit 3 is to suppress the peak value of the drain 81 voltage.

The feedback circuit 4 includes a sampling resistor, and the main function of the feedback circuit 4 is to proportionally sense the secondary AC voltage through the transformer primary supply winding and to deliver the induced AC voltage to the control circuit 7 via the sampling resistor.

The flyback switching circuit 5 includes a flyback transformer (i.e., a transformer used in a flyback switching power supply as described above), a switching transistor, and a current detecting resistor. Wherein, both ends of the primary winding of the flyback transformer are respectively connected with Buck (DC power supply bus) 82 and Drain (Drain) 81 in the absorbing circuit 3, and both ends (A and B) of the secondary winding are respectively output The positive terminal of the output rectifying diode in the rectifying and filtering circuit 6 is connected to the ground, and the two ends of the chip auxiliary power supply winding (VDD winding) 83 are respectively connected to the ground (GND) 84 and the power supply terminal C in the control circuit 7, and the mask The winding is connected to the GND 84 of the VDD winding 83.

The output rectification filter circuit 6 includes two main parts of an output rectifying diode and a filter capacitor. For different output ripple requirements, the output rectification filter circuit 6 can add a p-type filter circuit or a common mode filter circuit.

The primary device of control circuit 7 is a pulse width modulated drive die (e.g., OB2540 or similarly functioning control die) and the necessary peripheral auxiliary components. The pulse width modulation driving chip includes but is not limited to six functional pins, respectively: A: compensation pin, external capacitor to GND 84; B: current detecting pin, used for detecting voltage signal, for turning off and protecting, etc. Features; C: switch tube drive pin for driving switch tube Q1, connected to flyback switch circuit 5 through switch tube Q1; D: feedback signal pin for output voltage detection, connected to feedback circuit 4; E: GND 84 is grounded F: The power supply pin is used to provide the working voltage, and the rectification and filtering power supply circuit through the C point is connected to the flyback switch circuit 5.

2A and 2B are block diagrams showing the winding structure of a transformer used in a flyback switching power supply according to an embodiment of the present invention, in which black dots indicate winding points. Specifically, FIG. 2A shows a winding structure diagram of a transformer used in a flyback switching power supply according to an embodiment of the present invention, and FIG. 2B shows a cold spot winding according to the present invention. A winding structure diagram of a transformer used in a flyback switching power supply of an embodiment.

As shown in FIGS. 2A and 2B, the transformer used in the flyback switching power supply according to the embodiment of the present invention includes a skeleton, a pair of magnetic cores, a set of primary windings, a set of secondary windings, and a set of wafers. Auxiliary power windings, a set of shroud windings, and insulating tape. Wherein, the winding sequence of each winding in the transformer used in the flyback switching power supply is as follows: primary winding→ wafer auxiliary power supply winding→mask winding→secondary winding.

In the process of winding a transformer used in a flyback switching power supply according to an embodiment of the present invention (ie, the flyback transformer described above), it is necessary to add 1 ^to 8 layers of insulating tape between the windings for convenience. The next layer of windings can be smoothly wound to improve the consistency of the transformer; after completing the winding of the primary winding, the chip auxiliary power supply winding, the mask winding, and the secondary winding, the windings are made of 2 ^to 3 layers of insulating tape. Finally, the core and the bobbin are mated and secured with insulating tape to form a novel flyback transformer in accordance with an embodiment of the present invention.

In an embodiment, the primary winding can be wound by a single wire around three layers without an insulating tape in the middle to improve the winding efficiency of the transformer; the wafer auxiliary power supply winding can be wound by single or double wires. And it occupies a skeleton width of 1/2 ^~ 3/4 of the entire skeleton; the mask winding can be covered with a Copper 85, one end of the enameled wire is connected to the Copper 85, and one end is connected to the GND 84 of the primary side of the skeleton. The copper skin 85 preferably has a length of 0.6 ^to 0.9 turns; the secondary winding may be a triple insulated wire and is located at the outermost layer with respect to the other windings in the flyback transformer. After the winding of each winding in the flyback transformer is completed, 2 ^to 3 layers of tape are applied to fix the windings.

In the transformer used in the flyback switching power supply according to the embodiment of the present invention, both ends of the primary winding are respectively connected to the two legs of the primary side of the skeleton (Buck 82 and Drain 81); the chip auxiliary power supply winding ( The two ends of the VDD winding 83 are respectively connected to the ground pin (GND) 84 and the signal output pin (VDD) 86 of the primary side of the skeleton; the cover winding is covered with a Copper 85, and one end of the enameled wire is connected to the Copper 85, one end Connect to the GND 84 pin on the primary side of the skeleton (the enameled wire in Figures 2A and 2B is connected to the center of the Copper 85. In practice, the enameled wire can also be connected to the front or rear end of the Copper 85); Connect to the two legs of the secondary side of the skeleton (B and A, B connected to the ground of the output capacitor, A connected to the positive terminal of the output rectifier diode).

This creation considers the consistency of the mass production performance consistency of the product, reduces the number of processes of transformer winding, greatly improves the production efficiency of the transformer, and thus reduces the production cost of the transformer.

The present invention has been described above with reference to the specific embodiments of the present invention, and it is understood by those skilled in the art that various modifications, combinations and changes may be made without departing from the scope of the appended claims. The spirit and scope of this creation.

81‧‧‧Drain

82‧‧‧DC power bus (Buck)

83‧‧‧ wafer auxiliary power supply (VDD winding)

84‧‧‧ Grounding (GND)

85‧‧‧ Copper (Copper)

86‧‧‧Signal output pin (VDD)

Claims (6)

A transformer for use in a flyback switching power supply, comprising a skeleton having a primary side and a secondary side, a magnetic core, a primary winding, a secondary winding, a chip auxiliary power supply winding, a mask winding, and an insulating tape, wherein the magnetic core is disposed The skeleton is fixed by an insulating tape, and the two ends of the primary winding are respectively connected to a drain of a primary side of the skeleton and a DC power bus (Buck); a grounding pin (GND) and a signal output pin (VDD) connected to the primary side of the skeleton; the mask winding is connected to the chip auxiliary power supply winding; the two ends of the secondary winding are respectively connected to the grounding and output rectification of the output capacitor of the skeleton secondary side a positive terminal of the diode, and the primary winding, the secondary winding, the wafer auxiliary power supply winding, and the mask winding are wound in the following order: the primary winding → the wafer assist Power supply winding → said mask winding → said secondary winding. A transformer for use in a flyback switching power supply according to claim 1, wherein the wafer auxiliary power supply winding is wound by a single or double wire, and the occupied skeleton width is The entire width of the skeleton is 1/2 to 3/4. The transformer for use in a flyback switching power supply according to claim 1, wherein the mask winding is a copper cover, wherein the length of the copper is 0.6 to 0.9 turns, and the enameled wire is used. A grounding leg connected to the copper skin at one end and to the primary side of the bobbin at the other end. A transformer for use in a flyback switching power supply according to claim 1, wherein the primary winding, the secondary winding, the die auxiliary power supply winding, and the mask winding are There are 1 to 8 layers of insulating tape between the windings. The transformer for use in a flyback switching power supply according to claim 1, wherein the primary winding is formed by winding a single wire and three layers without insulating tape at one time. . A transformer for use in a flyback switching power supply according to claim 1, wherein the secondary winding is wound by a triple insulated wire and is opposite to the primary winding The wafer auxiliary power supply winding, and the shroud winding, are located at the outermost layer.