A planar transformer and a coupled self-powered circuit constituted by the same

Abstract

The application discloses a flat transformer, characterized in comprising a primary energy storage winding layer NP and an output winding layer NS. The application also discloses a coupled self-powered circuit constituted by the flat transformer, characterized in comprising the flat transformer, a PWM chip, a field effect transistor MOS and a charging circuit. The copper sheet arranged on the 3-pin OC lead-out wire of the primary energy storage winding layer is coupled with the multi-layer copper sheet to constitute a coupling capacitor, the coupling capacitor serves as a power supply electrode of the flat transformer, can well replace the power supply winding layer of the existing flat transformer, thereby well reducing the volume of the flat transformer and effectively reducing the cost of the flat transformer.

Description

Technical Field

[0001] This invention relates to the field of electronic technology, specifically to a planar transformer and a coupled self-powered circuit thereof. Background Technology

[0002] With the rise of wide-bandgap semiconductors (GANs), the number of power adapters used in conjunction with them is increasing, and the frequencies are also rising. The use of planar transformers in power supply circuits is becoming more widespread. However, existing planar transformers used in power supply circuits typically consist of a primary energy storage winding layer (NP), an output winding layer (NS), and a power supply winding layer (NA), resulting in large size and high production costs. Therefore, developing a planar transformer that can reduce both size and cost is a pressing need in this field. Summary of the Invention

[0003] The purpose of this invention is to overcome the aforementioned defects of existing planar transformers and to provide a planar transformer and a coupled self-powered circuit thereof.

[0004] The objective of this invention is achieved through the following technical solution: a planar transformer, comprising a primary energy storage winding layer NP and an output winding layer NS; a copper sheet Cu1 is provided on the OC lead of the 3rd pin of the primary energy storage winding layer NP, and copper foil Cu2 matching the copper sheet Cu1 is laid on the upper and lower layers of the primary energy storage winding layer NP, and the copper sheet Cu1 and the copper foil Cu2 are coupled to form a coupling capacitor C1, which serves as the power supply electrode of the planar transformer.

[0005] Furthermore, the area of ​​the copper sheet Cu1 is larger than the area of ​​the OC lead-out of pin 3 of the primary energy storage winding layer NP.

[0006] Furthermore, the number of copper foils Cu2 is two or more, and the number of copper foils Cu2 is even. Changing the number and / or area of ​​copper foils Cu2 and copper sheets Cu1 can adjust the capacitance of coupling capacitor C1.

[0007] The coupled self-powered circuit composed of the aforementioned planar transformer includes a planar transformer, a PWM chip, a field-effect transistor (MOS), and a charging circuit. The gate of the MOS is connected to the GATE pin of the PWM chip through a resistor R2, and the HV pin of the PWM chip is connected to pin 1 of the primary energy storage winding layer NP through a resistor R1. The drain of the MOS is connected to pin 3 of the primary energy storage winding layer NP and the positive terminal of the coupling capacitor C1, respectively. The charging circuit is connected to the negative terminal of the coupling capacitor C1.

[0008] Furthermore, the charging circuit includes a diode D2, an inductor L, and a capacitor C2; the P-terminal of the diode D2 is connected to the negative terminal of the coupling capacitor C1, the inductor L is connected in series between the N-terminal of the diode D2 and the positive terminal of the capacitor C2, and the connection point between the positive terminal of the capacitor C2 and the inductor L is connected to the VCC pin of the PWM chip; the negative terminal of the capacitor C2 and the GND pin of the PWM chip are grounded respectively.

[0009] A diode D1 is also provided on the negative terminal of the coupling capacitor C1. The diode D1 is used for energy storage and discharge. The N terminal of the diode D1 is connected to the negative terminal of the coupling capacitor C1, and the P terminal is grounded.

[0010] In addition, a resistor R3 is provided on the source of the field-effect transistor MOS. One end of the resistor R3 is connected to the source of the field-effect transistor MOS and the CS pin of the PWM chip, and the other end is grounded.

[0011] The PWM chip is a DK065G quasi-resonant flyback control AC-DC power switch chip.

[0012] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0013] (1) The present invention uses a copper sheet on the OC lead of the 3rd pin of the primary energy storage winding layer to couple with multiple layers of copper foil to form a coupling capacitor. This coupling capacitor serves as the power supply electrode of the planar transformer and can effectively replace the power supply winding layer of the existing planar transformer, thereby significantly reducing the volume of the planar transformer and effectively reducing the cost of the planar transformer.

[0014] (2) The copper sheet of the present invention is coupled with multiple layers of copper foil to form a coupling capacitor with adjustable capacitance and is not easily attenuated. It is not easily broken down by high voltage and can effectively ensure the power supply stability of the power supply circuit. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the planar transformer of the present invention.

[0016] Figure 2 This is a schematic diagram of the copper foil Cu2 of the flat-plate transformer of the present invention.

[0017] Figure 3 This is a schematic diagram of the circuit structure of the coupled self-powered circuit constructed from the planar transformer of the present invention. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0019] Example 1

[0020] like Figure 1 and Figure 2 As shown, the objective of this invention is achieved through the following technical solution: a planar transformer, comprising a primary energy storage winding layer NP and an output winding layer NS. Specifically, in this embodiment, the power supply winding layer is eliminated, which greatly reduces the size and production cost of the planar transformer. To enable it to supply power, a copper sheet Cu1 is provided on the OC lead of pin 3 of the primary energy storage winding layer NP, and the area of ​​the copper sheet Cu1 is larger than the area of ​​the OC lead of pin 3 of the primary energy storage winding layer NP. Simultaneously, copper foil Cu2 matching the copper sheet Cu1 is laid on the upper and lower layers of the primary energy storage winding layer NP, and the copper sheet Cu1 and copper foil Cu2 are coupled to form a coupling capacitor C1, which serves as the power supply electrode of the planar transformer. The capacitance of the coupling capacitor C1, formed by the coupling of the copper sheet Cu1 and the multiple layers of copper foil Cu2, is adjustable, not easily attenuated, and not easily broken down by high voltage, effectively ensuring the power supply stability of the planar transformer and the power supply circuit it constitutes.

[0021] The number of copper foils Cu2 is two or more, and the number of copper foils Cu2 is even. In practical applications, the capacitance of the coupling capacitor C1 can be adjusted by changing the number and / or area of ​​the copper foils Cu2 and copper sheets Cu1, thereby adjusting the output voltage and current.

[0022] Example 2

[0023] The coupled self-powered circuit, constructed from the planar transformer in Example 1, includes the planar transformer, a PWM chip, a field-effect transistor (MOS), and a charging circuit. For example... Figure 3 As shown, specifically, in this embodiment, the PWM chip is preferably implemented using the DK065G quasi-resonant flyback control AC-DC power switch chip, and the MOSFET is preferably implemented using the KIA4750S switching transistor. In actual use, the models of the PWM chip and the MOSFET can be adjusted as needed.

[0024] In this circuit, the gate of the MOSFET is connected to the GATE pin of the PWM chip via a 10kΩ resistor R2. The HV pin of the PWM chip is connected to pin 1 of the primary energy storage winding layer NP via a 4kΩ resistor R1. The drain of the MOSFET is connected to pin 3 of the primary energy storage winding layer NP and the positive terminal of the coupling capacitor C1, while the charging circuit is connected to the negative terminal of the coupling capacitor C1.

[0025] like Figure 3As shown, the charging circuit includes a diode D2, an inductor L, and a capacitor C2. Specifically, in this embodiment, diode D2 is preferably a 1N4012 charging rectifier diode, and the P-terminal of diode D2 is connected to the negative terminal of coupling capacitor C1. The inductor L has a self-inductance of 50μH and is connected in series between the N-terminal of diode D2 and the positive terminal of capacitor C2. The connection point between the positive terminal of capacitor C2 and inductor L is connected to the VCC pin of the PWM chip. The capacitance of capacitor C2 is 0.1μF, and its negative terminal is grounded to the GND pin of the PWM chip.

[0026] To prevent excessive voltage in the primary energy storage winding layer NP of the flat-plate transformer during energy storage, which could damage the transformer, a diode D1 (model SD36CW) is placed on the negative terminal of the coupling capacitor C1. The N-terminus of diode D1 is connected to the negative terminal of coupling capacitor C1, and its P-terminus is grounded. In operation, diode D1 is used for energy storage discharge. When the primary energy storage winding layer NP of the flat-plate transformer is conducting and storing energy, coupling capacitor C1 discharges through the field-effect transistor (MOSFET) and diode D1. Diode D1 discharges the large current through the line to ground and also limits the voltage of the primary energy storage winding layer NP and coupling capacitor C1 to a low potential, thus protecting the flat-plate transformer and the power supply circuit. When the primary energy storage winding layer NP of the flat-plate transformer stops storing energy, after the overvoltage surge of coupling capacitor C1 disappears, diode D1 quickly returns to a high-resistance state of ≥10GΩ, ensuring the normal operation of the power supply circuit.

[0027] Meanwhile, to ensure the discharge performance of the MOSFET, a 10kΩ resistor R3 is placed on the source of the MOSFET. One end of resistor R3 is connected to the source of the MOSFET and the CS pin of the PWM chip, and the other end is grounded to ensure the normal operation of the power supply circuit after the overvoltage surge disappears.

[0028] In practical use, the externally input voltage passes through the planar transformer, and the current charges the coupling capacitor C1. Once C1 reaches saturation, its output current raises the voltage level on diode D2, causing it to conduct. At this time, current flows through inductor L to power capacitor C2. Both C1 and C2 are charging. Simultaneously, the PWM chip starts working, outputting a square wave to drive the field-effect transistor MOS, which then conducts. The primary energy storage winding layer NP conducts to store energy, and the coupling capacitor C1 discharges through the MOS and diode D1. When the PWM chip is turned off, the MOS is cut off, and the reverse voltage generated by the planar transformer is superimposed on the input voltage. Simultaneously, current charges the coupling capacitor C1, forming a capacitor pump charging and discharging coupled self-powered circuit. (Copper foil Cu2 and copper sheet Cu1 are also mentioned.)

[0029] This invention utilizes a copper sheet Cu1 coupled with multiple layers of copper foil Cu2 on the OC lead of the primary energy storage winding layer to form a coupling capacitor C1. This coupling capacitor C1 serves as the power supply electrode of a planar transformer, effectively replacing the power supply winding layer of existing planar transformers, thereby significantly reducing the size and cost of the planar transformer. Furthermore, the capacitance of the coupling capacitor formed by the copper sheet Cu1 and the multiple layers of copper foil Cu2 is adjustable and not easily attenuated, making it less susceptible to high-voltage breakdown and effectively ensuring the power supply stability of the power supply circuit.

[0030] As described above, the present invention can be well implemented.

Claims

1. A coupled self-powered circuit composed of a planar transformer, characterized in that, The system includes a planar transformer, a PWM chip, a field-effect transistor (MOS), and a charging circuit. The planar transformer comprises a primary energy storage winding layer NP and an output winding layer NS. A copper sheet Cu1 is disposed on the OC lead of pin 3 of the primary energy storage winding layer NP. Copper foils Cu2, matching the copper sheet Cu1, are respectively laid on the upper and lower layers of the primary energy storage winding layer NP. The copper sheet Cu1 and the copper foil Cu2 are coupled to form a coupling capacitor C1, which serves as the power supply electrode of the planar transformer. The area of ​​the copper sheet Cu1 is larger than the area of ​​the OC lead of pin 3 of the primary energy storage winding layer NP. The number of copper foils Cu2 is two or more, and the number of copper foils Cu2 is even. Changing the number and / or area of ​​copper foils Cu2 and copper sheets Cu1 can adjust the capacitance of coupling capacitor C1. The gate of the field-effect transistor MOS is connected to the GATE pin of the PWM chip through resistor R2. The HV pin of the PWM chip is connected to pin 1 of the primary energy storage winding layer NP through resistor R1. The drain of the field-effect transistor MOS is connected to pin 3 of the primary energy storage winding layer NP and the positive terminal of coupling capacitor C1, respectively. The charging circuit is connected to the negative terminal of coupling capacitor C1.

2. The coupled self-powered circuit composed of a planar transformer according to claim 1, characterized in that, The charging circuit includes a diode D2, an inductor L, and a capacitor C2; the P-terminal of the diode D2 is connected to the negative terminal of the coupling capacitor C1, the inductor L is connected in series between the N-terminal of the diode D2 and the positive terminal of the capacitor C2, and the connection point between the positive terminal of the capacitor C2 and the inductor L is connected to the VCC pin of the PWM chip; the negative terminal of the capacitor C2 and the GND pin of the PWM chip are grounded respectively.

3. The coupled self-powered circuit composed of a planar transformer according to claim 2, characterized in that, A diode D1 is also provided on the negative terminal of the coupling capacitor C1. The diode D1 is used for energy storage and discharge. The N terminal of the diode D1 is connected to the negative terminal of the coupling capacitor C1, and the P terminal is grounded.

4. The coupled self-powered circuit composed of a planar transformer according to claim 3, characterized in that, A resistor R3 is provided on the source of the field-effect transistor MOS. One end of the resistor R3 is connected to the source of the field-effect transistor MOS and the CS pin of the PWM chip, and the other end is grounded.

5. The coupled self-powered circuit composed of a planar transformer according to claim 4, characterized in that, The PWM chip is a DK065G quasi-resonant flyback control AC-DC power switch chip.

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