A wide input range multi-coil winding switching power supply

Abstract

This invention relates to a multi-coil switching power supply with a wide input range, comprising a switching transformer T2 with three series-connected primary windings, whose secondary windings output negative feedback voltage, 12V, 24V, and 5V respectively; pin 4 of the main control chip U3 is grounded via resistor R28, and also via resistor R28' and phototransistor U6b; LED U6a is connected to the secondary winding Le, which controls transistor Q8, which in turn controls LED U6a, achieving PFM control. Therefore, by using a switching transformer with three series-connected primary windings, the input voltage is divided into three equal parts, allowing it to withstand a wide input range voltage. Furthermore, the PFM control method developed for the PWM control chip achieves good regulation of the wide input range voltage, making it suitable for photovoltaic power plants, wind power, and energy storage.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and in particular to a multi-coil winding switching power supply with a wide input range. Background Technology

[0002] The voltage output of photovoltaic (PV) panels fluctuates significantly with sunlight intensity, typically ranging from 200V to 1500V. This means the voltage output of the same PV panel can differ by several times at different times, necessitating a multi-coil switching power supply adaptable to a wide input range. Furthermore, the monitoring and control system of a PV power plant is also powered by the PV panels. Many sensors, computers, and other components in this system require low-voltage DC power supplies of 5V, 12V, and 24V, which differs greatly from the voltage output of the PV panels. Therefore, the switching power supply for a PV power plant must not only be compatible with the wide input range of the PV panels but also output low-voltage DC power suitable for the monitoring and control system. Simultaneously, it must be adaptable to wind power and energy storage applications. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art. This invention provides a multi-coil switching power supply with a wide input range. It is equipped with a switching transformer with three series-connected primary windings, which divides the input voltage equally into three parts, can withstand a wide input range voltage, and develops a PFM control mode for PWM control chips to achieve good regulation of the wide input range voltage, making it suitable for photovoltaic power plants.

[0004] This invention discloses a multi-coil winding switching power supply with a wide input range, characterized in that it comprises:

[0005] The switching transformer T2 has primary coils La, Lb and Lc connected in series, a primary feedback coil Ld, and secondary coils Le, Lf, Lg and Lh.

[0006] Among them, the secondary coil Le is used to output the negative feedback voltage, the secondary coil Lf is used to output 12V voltage, the secondary coil Lg is used to output 24V voltage, and the secondary coil Lh is used to output 5V voltage.

[0007] The positive terminal V+ of the input power supply is grounded through the primary coil La, field-effect transistor V1, primary coil Lb, field-effect transistor V2, primary coil Lc, field-effect transistor V3, resistor R46, and resistor R47.

[0008] The drive transformer T1 has a primary coil L0, a secondary coil Li, a secondary coil Lj, and a secondary coil Lk;

[0009] NPN transistor Q4 and PNP transistor Q5 form a totem pole. Pin 8 GATE of the main control chip U3 is connected to the primary coil L0 of the totem pole via resistor R26 to form a drive unit and execute PWM control.

[0010] Pin 4, RI of the main control chip U3, is grounded through resistor R28. Pin 4, RI, is also grounded through resistor R28' and phototransistor U6b.

[0011] The LED U6a corresponding to the phototransistor U6b is connected to the output terminal of the secondary coil Le. The output voltage Vo+ of the secondary coil Le controls the base current of the transistor Q8. The base current of the transistor Q8 controls the current value flowing through the LED U6a, which is used by the main control chip U3 to perform PFM control.

[0012] Preferably, the primary coil La is connected to the drain of the field-effect transistor V1, the source of the field-effect transistor V1 is connected to the primary coil Lb, the primary coil Lb is connected to the drain of the field-effect transistor V2, the source of the field-effect transistor V2 is connected to the primary coil Lc, the primary coil Lc is connected to the drain of the field-effect transistor V3, and the source of the field-effect transistor V3 is connected to resistors R46 and R47 in parallel, and finally grounded.

[0013] Preferably, the secondary coil Li is used to drive the field-effect transistor V1, the secondary coil Lj is used to drive the field-effect transistor V2, and the secondary coil Lk is used to drive the field-effect transistor V3.

[0014] The primary-side feedback coil Ld generates voltage during the DC / DC conversion process.

[0015] Preferably, one end of capacitor C9 and one end of resistor R31 are both connected to the positive terminal V+ of the input power supply and one end of the primary coil La. The other end of the primary coil La is connected to the drain of the field-effect transistor V1. The other end of capacitor C9 and the other end of resistor R31 are both connected to one end of capacitor C10 and one end of resistor R32.

[0016] The other end of capacitor C10 and the other end of resistor R32 are both connected to one end of the primary coil Lb, the source of field-effect transistor V1, one end of capacitor C11 and one end of resistor R33. The other end of capacitor C11 and the other end of resistor R33 are both connected to one end of capacitor C12 and one end of resistor R34.

[0017] The other end of capacitor C12 and the other end of resistor R34 are both connected to one end of the primary coil Lc, the source of field-effect transistor V2, one end of capacitor C13 and one end of resistor R35. The other end of capacitor C13 and the other end of resistor R35 are both connected to one end of capacitor C14 and one end of resistor R36.

[0018] The other end of capacitor C14 is grounded, as is the other end of resistor R36.

[0019] Preferably, one end of the secondary coil Li is connected to one end of the resistor R37, the other end of the resistor R37 is connected to one end of the resistor R38 and the gate of the field-effect transistor V1, the other end of the secondary coil Li is connected to the other end of the resistor R38 and the source of the field-effect transistor V1, and the drain of the field-effect transistor V1 is connected to one end of the primary coil La.

[0020] One end of the secondary coil Lj is connected to one end of resistor R40, the other end of resistor R40 is connected to one end of resistor R41 and the gate of field-effect transistor V2, the other end of the secondary coil Lj is connected to the other end of resistor R41 and the source of field-effect transistor V2, and the drain of field-effect transistor V2 is connected to one end of the primary coil Lb.

[0021] One end of the secondary coil Lk is connected to one end of resistor R43, the other end of resistor R43 is connected to one end of resistor R44 and the gate of field-effect transistor V3, the other end of the secondary coil Lk is connected to the other end of resistor R44 and the source of field-effect transistor V3, and the drain of field-effect transistor V3 is connected to one end of the primary coil Lc.

[0022] Preferably, one end of the secondary coil Le is connected to the positive terminal of diode D14, the negative terminal of diode D14 is connected to one end of resistor R63 and one end of resistor R66, the other end of resistor R63 is connected to one end of resistor R64 and the positive terminal of LED U6a, and the negative terminal of LED U6a is connected to the other end of the secondary coil Le.

[0023] The other end of resistor R64 is connected to the collector of NPN transistor Q8. The emitter of NPN transistor Q8 is connected to the other end of the secondary coil Le. The other end of resistor T66 is connected to the negative terminal of Zener diode DZ3. The positive terminal of Zener diode DZ3 is connected to the base of NPN transistor Q8 and one end of resistor R65. The other end of resistor R65 is connected to the other end of the secondary coil Le.

[0024] Preferably, resistor R28' is connected in series with phototransistor U6b to generate the first equivalent resistance;

[0025] Resistor R28, resistor R28', and phototransistor U6b are connected in parallel to generate a second equivalent resistance;

[0026] The resistance value of the first equivalent resistor is controlled by the light intensity of the light-emitting diode U6a.

[0027] Preferably, the positive terminal Uin+ of the DC power supply is connected to one end of the filter inductor L1, the other end of the filter inductor L1 is connected to one end of resistor R14 and one end of resistor R18, the other end of resistor R14 is connected to the collector of transistor Q1, the emitter of transistor Q1 is connected to one end of resistor R15, the base of transistor Q1 is connected to one end of resistor R20 and the collector of phototransistor U4b, the other end of resistor R18 is connected to one end of resistor R19, the other end of resistor R19 is connected to the other end of resistor R20 and connected to the cathode pin and reference pin of component U1, and the anode pin of component U1 is connected to the other end of resistor R15 and the emitter of phototransistor U4b, thus forming a first-stage constant current source;

[0028] The other end of resistor R15 is connected to one end of resistor R6 and one end of resistor R21. The other end of resistor R16 is connected to the collector of transistor Q2. The emitter of transistor Q2 is connected to one end of resistor R17. The base of transistor Q2 is connected to one end of resistor R23 and the collector of phototransistor U3b. The other end of resistor R21 is connected to one end of resistor R22. The other end of resistor R22 is connected to the other end of resistor R23 and the cathode and reference pins of component U2. The anode pin of component U2 is connected to the other end of resistor R17 and the emitter of phototransistor U3b, forming a two-stage constant current source.

[0029] Preferably, the secondary constant current source is output through resistor R17 to power pin Vin of the main control chip U3, so as to enable the main control chip U3 to start.

[0030] Preferably, the negative terminal of rectifier diode D4 is connected to the negative terminal of Zener diode DZ1 via resistor R24, the positive terminal of Zener diode DZ1 is connected to the positive terminal of LED U3a, the negative terminal of LED U3a is connected to the positive terminal of LED U4a, and the negative terminal of LED U4a is connected to pin 6 SENSE of main control chip U3.

[0031] Resistor R25 is connected across the positive terminal of LED U3a and the negative terminal of LED U4a.

[0032] As can be seen, by setting up a switching transformer with three series-connected primary windings, the input voltage is divided into three equal parts, which can withstand a wide input voltage range. Furthermore, a PFM control method developed for PWM control chips enables good regulation of the wide input voltage range, making it suitable for photovoltaic power plants. It is also adaptable to wind power and energy storage applications. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the circuit principle of a multi-coil winding switching power supply with a wide input range according to the present invention;

[0034] Figure 2 This is a schematic diagram of the circuit principle of the topology of the main control chip U3 in a multi-coil winding switching power supply with a wide input range according to the present invention to realize negative feedback control;

[0035] Figure 3 This is a schematic diagram of the circuit principle of the primary constant current source and the secondary constant current source in a multi-coil winding switching power supply with a wide input range according to the present invention. Detailed Implementation

[0036] To enhance understanding of the present invention, it will be further described in detail below with reference to embodiments and accompanying drawings. The present invention can be implemented in the following ways:

[0037] Please refer to Figures 1-3 A multi-coil winding switching power supply with a wide input range may include the following:

[0038] The switching transformer T2 has primary coils La, Lb and Lc connected in series, a primary feedback coil Ld, and secondary coils Le, Lf, Lg and Lh.

[0039] Among them, the secondary coil Le is used to output the negative feedback voltage, the secondary coil Lf is used to output 12V voltage, the secondary coil Lg is used to output 24V voltage, and the secondary coil Lh is used to output 5V voltage.

[0040] The positive terminal V+ of the input power supply is grounded through the primary coil La, field-effect transistor V1, primary coil Lb, field-effect transistor V2, primary coil Lc, field-effect transistor V3, resistor R46, and resistor R47.

[0041] The drive transformer T1 has a primary coil L0, a secondary coil Li, a secondary coil Lj, and a secondary coil Lk;

[0042] NPN transistor Q4 and PNP transistor Q5 form a totem pole. Pin 8 GATE of the main control chip U3 is connected to the primary coil L0 of the totem pole via resistor R26 to form a drive unit and execute PWM control.

[0043] Pin 4, RI of the main control chip U3, is grounded through resistor R28. Pin 4, RI, is also grounded through resistor R28' and phototransistor U6b.

[0044] The LED U6a corresponding to the phototransistor U6b is connected to the output terminal of the secondary coil Le. The output voltage Vo+ of the secondary coil Le controls the base current of the transistor Q8. The base current of the transistor Q8 controls the current value flowing through the LED U6a, which is used by the main control chip U3 to perform PFM control.

[0045] Here, by adding PFM control capability to the main control chip U3, which has PWM control capability, it can accurately regulate the voltage over a wide input range, avoiding problems such as voltage over-limit.

[0046] In addition, the switching transformer T2 is equipped with three primary windings connected in series, which can divide the input voltage into three equal parts, thereby compressing the threshold of the input voltage from a physical perspective and preventing the switching power supply from being impacted by large-scale voltage fluctuations.

[0047] Therefore, by compressing the input voltage threshold and improving the voltage regulation capability through PFM, good regulation can be achieved for facilities with a wide input range, such as photovoltaic power plants, ensuring stable circuit operation and outputting compliant low-voltage DC power.

[0048] In this embodiment, the primary coil La is connected to the drain of the field-effect transistor V1, the source of the field-effect transistor V1 is connected to the primary coil Lb, the primary coil Lb is connected to the drain of the field-effect transistor V2, the source of the field-effect transistor V2 is connected to the primary coil Lc, the primary coil Lc is connected to the drain of the field-effect transistor V3, and the source of the field-effect transistor V3 is connected to resistors R46 and R47 in parallel, and finally grounded.

[0049] In this embodiment, the secondary coil Li is used to drive the field-effect transistor V1, the secondary coil Lj is used to drive the field-effect transistor V2, and the secondary coil Lk is used to drive the field-effect transistor V3.

[0050] The primary-side feedback coil Ld generates voltage during the DC / DC conversion process.

[0051] In this embodiment, one end of capacitor C9 and one end of resistor R31 are both connected to the positive terminal V+ of the input power supply and one end of the primary coil La. The other end of the primary coil La is connected to the drain of the field-effect transistor V1. The other end of capacitor C9 and the other end of resistor R31 are both connected to one end of capacitor C10 and one end of resistor R32.

[0052] The other end of capacitor C10 and the other end of resistor R32 are both connected to one end of the primary coil Lb, the source of field-effect transistor V1, one end of capacitor C11 and one end of resistor R33. The other end of capacitor C11 and the other end of resistor R33 are both connected to one end of capacitor C12 and one end of resistor R34.

[0053] The other end of capacitor C12 and the other end of resistor R34 are both connected to one end of the primary coil Lc, the source of field-effect transistor V2, one end of capacitor C13 and one end of resistor R35. The other end of capacitor C13 and the other end of resistor R35 are both connected to one end of capacitor C14 and one end of resistor R36.

[0054] The other end of capacitor C14 is grounded, as is the other end of resistor R36.

[0055] In this embodiment, one end of the secondary coil Li is connected to one end of the resistor R37, the other end of the resistor R37 is connected to one end of the resistor R38 and the gate of the field-effect transistor V1, the other end of the secondary coil Li is connected to the other end of the resistor R38 and the source of the field-effect transistor V1, and the drain of the field-effect transistor V1 is connected to one end of the primary coil La.

[0056] One end of the secondary coil Lj is connected to one end of resistor R40, the other end of resistor R40 is connected to one end of resistor R41 and the gate of field-effect transistor V2, the other end of the secondary coil Lj is connected to the other end of resistor R41 and the source of field-effect transistor V2, and the drain of field-effect transistor V2 is connected to one end of the primary coil Lb.

[0057] One end of the secondary coil Lk is connected to one end of resistor R43, the other end of resistor R43 is connected to one end of resistor R44 and the gate of field-effect transistor V3, the other end of the secondary coil Lk is connected to the other end of resistor R44 and the source of field-effect transistor V3, and the drain of field-effect transistor V3 is connected to one end of the primary coil Lc.

[0058] In this embodiment, one end of the secondary coil Le is connected to the positive terminal of diode D14, the negative terminal of diode D14 is connected to one end of resistor R63 and one end of resistor R66, the other end of resistor R63 is connected to one end of resistor R64 and the positive terminal of light-emitting diode U6a, and the negative terminal of light-emitting diode U6a is connected to the other end of the secondary coil Le.

[0059] The other end of resistor R64 is connected to the collector of NPN transistor Q8. The emitter of NPN transistor Q8 is connected to the other end of the secondary coil Le. The other end of resistor T66 is connected to the negative terminal of Zener diode DZ3. The positive terminal of Zener diode DZ3 is connected to the base of NPN transistor Q8 and one end of resistor R65. The other end of resistor R65 is connected to the other end of the secondary coil Le.

[0060] In this embodiment, resistor R28' is connected in series with phototransistor U6b to generate the first equivalent resistance;

[0061] Resistor R28, resistor R28', and phototransistor U6b are connected in parallel to generate a second equivalent resistance;

[0062] The resistance value of the first equivalent resistor is controlled by the light intensity of the light-emitting diode U6a.

[0063] As can be seen, the negative feedback voltage output by the secondary coil Le can control the current at the base of transistor Q8, thereby controlling the current flowing through LED U6a. The light intensity emitted by LED U6a changes accordingly, and the resistance of phototransistor U6b changes accordingly. At this time, the first equivalent resistance changes, and then the second equivalent resistance changes with the change of the first equivalent resistance. This change is transmitted through pin 4 RI of the main control chip U3 to realize PFM control, achieving a wider range of voltage regulation capability than PWM control.

[0064] In this embodiment, the positive terminal Uin+ of the DC power supply is connected to one end of the filter inductor L1, the other end of the filter inductor L1 is connected to one end of resistor R14 and one end of resistor R18, the other end of resistor R14 is connected to the collector of transistor Q1, the emitter of transistor Q1 is connected to one end of resistor R15, the base of transistor Q1 is connected to one end of resistor R20 and the collector of phototransistor U4b, the other end of resistor R18 is connected to one end of resistor R19, the other end of resistor R19 is connected to the other end of resistor R20 and is connected to the cathode pin and reference pin of component U1, and the anode pin of component U1 is connected to the other end of resistor R15 and the emitter of phototransistor U4b, thus forming a first-stage constant current source.

[0065] The other end of resistor R15 is connected to one end of resistor R6 and one end of resistor R21. The other end of resistor R16 is connected to the collector of transistor Q2. The emitter of transistor Q2 is connected to one end of resistor R17. The base of transistor Q2 is connected to one end of resistor R23 and the collector of phototransistor U3b. The other end of resistor R21 is connected to one end of resistor R22. The other end of resistor R22 is connected to the other end of resistor R23 and the cathode and reference pins of component U2. The anode pin of component U2 is connected to the other end of resistor R17 and the emitter of phototransistor U3b, forming a two-stage constant current source.

[0066] In this embodiment, the secondary constant current source is output through resistor R17 to power pin Vin of the main control chip U3, so as to start the main control chip U3.

[0067] In this embodiment, the negative terminal of rectifier diode D4 is connected to the negative terminal of Zener diode DZ1 via resistor R24, the positive terminal of Zener diode DZ1 is connected to the positive terminal of LED U3a, the negative terminal of LED U3a is connected to the positive terminal of LED U4a, and the negative terminal of LED U4a is connected to pin 6 SENSE of main control chip U3.

[0068] Resistor R25 is connected across the positive terminal of LED U3a and the negative terminal of LED U4a.

[0069] Here, the secondary constant current source controls the phototransistors U3b and U4b to be in the on and off states based on the switching of LEDs U3a and U4a, thereby controlling the secondary constant current source to be in the working state or the off state.

[0070] Therefore, by using the above-described turn-off constant current source design, the problems of excessive power consumption and heat generation associated with resistor-based voltage reduction startup are avoided, thus improving circuit stability and efficiency.

[0071] In summary, a switching transformer with three series-connected primary windings is used to equally divide the input voltage into three parts, enabling it to withstand a wide input voltage range. A PFM control method has been developed specifically for PWM control chips, achieving excellent regulation of the wide input voltage range, making it suitable for photovoltaic power plants. It is also adaptable to wind power and energy storage applications.

Claims

1. A multi-coil winding switching power supply with a wide input range, characterized in that, include: The switching transformer T2 has primary coils La, Lb and Lc connected in series, a primary feedback coil Ld, and secondary coils Le, Lf, Lg and Lh. Among them, the secondary coil Le is used to output the negative feedback voltage, the secondary coil Lf is used to output 12V voltage, the secondary coil Lg is used to output 24V voltage, and the secondary coil Lh is used to output 5V voltage. One end of the secondary coil Le is connected to the positive terminal of diode D14. The negative terminal of diode D14 is connected to one end of resistor R63 and one end of resistor R66. The other end of resistor R63 is connected to one end of resistor R64 and the positive terminal of LED U6a. The negative terminal of LED U6a is connected to the other end of the secondary coil Le. The other end of resistor R64 is connected to the collector of NPN transistor Q8, the emitter of NPN transistor Q8 is connected to the other end of secondary coil Le, the other end of resistor R66 is connected to the negative terminal of Zener diode DZ3, the positive terminal of Zener diode DZ3 is connected to the base of NPN transistor Q8 and one end of resistor R65, and the other end of resistor R65 is connected to the other end of secondary coil Le. The positive terminal V+ of the input power supply is grounded through the primary coil La, field-effect transistor V1, primary coil Lb, field-effect transistor V2, primary coil Lc, field-effect transistor V3, resistor R46, and resistor R47. The drive transformer T1 has a primary coil L0, a secondary coil Li, a secondary coil Lj, and a secondary coil Lk; NPN transistor Q4 and PNP transistor Q5 form a totem pole. Pin 8 GATE of the main control chip U3 is connected to the primary coil L0 of the totem pole via resistor R26 to form a drive unit and execute PWM control. Pin 4, RI of the main control chip U3, is grounded through resistor R28. Pin 4, RI, is also grounded through resistor R28' and phototransistor U6b. The LED U6a corresponding to the phototransistor U6b is connected to the output terminal of the secondary coil Le. The output voltage Vo+ of the secondary coil Le controls the base current of the transistor Q8. The base current of the transistor Q8 controls the current value flowing through the LED U6a, which is used by the main control chip U3 to perform PFM control.

2. The multi-coil winding switching power supply with a wide input range according to claim 1, characterized in that, include: The primary coil La is connected to the drain of the field-effect transistor V1. The source of the field-effect transistor V1 is connected to the primary coil Lb. The primary coil Lb is connected to the drain of the field-effect transistor V2. The source of the field-effect transistor V2 is connected to the primary coil Lc. The primary coil Lc is connected to the drain of the field-effect transistor V3. The source of the field-effect transistor V3 is connected to resistors R46 and R47 in parallel, and finally grounded.

3. The multi-coil winding switching power supply with a wide input range according to claim 1, characterized in that, include: Secondary coil Li is used to drive field-effect transistor V1, secondary coil Lj is used to drive field-effect transistor V2, and secondary coil Lk is used to drive field-effect transistor V3. The primary-side feedback coil Ld generates voltage during the DC / DC conversion process.

4. The multi-coil winding switching power supply with a wide input range according to claim 1, characterized in that, include: One end of capacitor C9 and one end of resistor R31 are both connected to the positive terminal V+ of the input power supply and one end of the primary coil La. The other end of the primary coil La is connected to the drain of the field-effect transistor V1. The other end of capacitor C9 and the other end of resistor R31 are both connected to one end of capacitor C10 and one end of resistor R32. The other end of capacitor C10 and the other end of resistor R32 are both connected to one end of the primary coil Lb, the source of field-effect transistor V1, one end of capacitor C11 and one end of resistor R33. The other end of capacitor C11 and the other end of resistor R33 are both connected to one end of capacitor C12 and one end of resistor R34. The other end of capacitor C12 and the other end of resistor R34 are both connected to one end of the primary coil Lc, the source of field-effect transistor V2, one end of capacitor C13 and one end of resistor R35. The other end of capacitor C13 and the other end of resistor R35 are both connected to one end of capacitor C14 and one end of resistor R36. The other end of capacitor C14 is grounded, as is the other end of resistor R36.

5. The multi-coil winding switching power supply with a wide input range according to claim 1, characterized in that, include: One end of the secondary coil Li is connected to one end of resistor R37, the other end of resistor R37 is connected to one end of resistor R38 and the gate of field-effect transistor V1, the other end of the secondary coil Li is connected to the other end of resistor R38 and the source of field-effect transistor V1, and the drain of field-effect transistor V1 is connected to one end of the primary coil La. One end of the secondary coil Lj is connected to one end of resistor R40, the other end of resistor R40 is connected to one end of resistor R41 and the gate of field-effect transistor V2, the other end of the secondary coil Lj is connected to the other end of resistor R41 and the source of field-effect transistor V2, and the drain of field-effect transistor V2 is connected to one end of the primary coil Lb. One end of the secondary coil Lk is connected to one end of resistor R43, the other end of resistor R43 is connected to one end of resistor R44 and the gate of field-effect transistor V3, the other end of the secondary coil Lk is connected to the other end of resistor R44 and the source of field-effect transistor V3, and the drain of field-effect transistor V3 is connected to one end of the primary coil Lc.

6. The multi-coil winding switching power supply with a wide input range according to claim 1, characterized in that, include: Resistor R28' is connected in series with phototransistor U6b to generate the first equivalent resistance; Resistor R28, resistor R28', and phototransistor U6b are connected in parallel to generate a second equivalent resistance; The resistance value of the first equivalent resistor is controlled by the light intensity of the light-emitting diode U6a.

7. The wide input range multi-coil winding switching power supply according to claim 1, characterized in that, include: The positive terminal Uin+ of the DC power supply is connected to one end of the filter inductor L1. The other end of the filter inductor L1 is connected to one end of resistor R14 and one end of resistor R18. The other end of resistor R14 is connected to the collector of transistor Q1. The emitter of transistor Q1 is connected to one end of resistor R15. The base of transistor Q1 is connected to one end of resistor R20 and the collector of phototransistor U4b. The other end of resistor R18 is connected to one end of resistor R19. The other end of resistor R19 is connected to the other end of resistor R20 and is connected to the cathode pin and reference pin of component U1. The anode pin of component U1 is connected to the other end of resistor R15 and the emitter of phototransistor U4b, forming a first-stage constant current source. The other end of resistor R15 is connected to one end of resistor R6 and one end of resistor R21. The other end of resistor R16 is connected to the collector of transistor Q2. The emitter of transistor Q2 is connected to one end of resistor R17. The base of transistor Q2 is connected to one end of resistor R23 and the collector of phototransistor U3b. The other end of resistor R21 is connected to one end of resistor R22. The other end of resistor R22 is connected to the other end of resistor R23 and the cathode and reference pins of component U2. The anode pin of component U2 is connected to the other end of resistor R17 and the emitter of phototransistor U3b, forming a two-stage constant current source.

8. The multi-coil winding switching power supply with a wide input range according to claim 7, characterized in that, include: The secondary constant current source is output through resistor R17 to power pin Vin of the main control chip U3, enabling the main control chip U3 to start.

9. The multi-coil winding switching power supply with a wide input range according to claim 7, characterized in that, include: The negative terminal of rectifier diode D4 is connected to the negative terminal of Zener diode DZ1 via resistor R24. The positive terminal of rectifier diode D4 is connected to one end of the primary side feedback coil Ld via resistor R30. The positive terminal of Zener diode DZ1 is connected to the positive terminal of LED U3a. The negative terminal of LED U3a is connected to the positive terminal of LED U4a. The negative terminal of LED U4a is connected to pin 7 Vdd of main control chip U3. Resistor R25 is connected across the positive terminal of LED U3a and the negative terminal of LED U4a.

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