Flyback power supply circuit based on planar transformer
By adopting a planar transformer core and PCB winding flyback power supply circuit, the problems of high cost, large size and difficulty in miniaturization of traditional wound flyback transformers are solved, achieving cost reduction and size reduction, and improving reliability and automated production capabilities.
Patent Information
- Application Number
- CN202510967958.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-14
- Publication Date
- 2025-09-19
AI Technical Summary
In existing flyback power supply technology, traditional wound flyback transformers have the problems of high cost, large size, difficulty in miniaturization and automated production, and require multiple sets of peripheral control circuits.
A flyback power supply circuit based on a planar transformer is used. The planar transformer core and PCB winding are used to replace the traditional wound flyback transformer, integrating it into a flyback power supply, reducing peripheral control circuit components, and adopting an automated molding process.
It reduces costs, reduces volume, improves power volume density, and achieves better control of reliability and quality.
Smart Images
Figure CN120675413A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of flyback power supplies, and in particular to a flyback power supply circuit based on a planar transformer. Background Art
[0002] A flyback power supply consists of an input power supply, input capacitors, a control chip, a primary MOSFET, a flyback transformer (a traditional wire-wound flyback transformer or a planar transformer), diodes (an auxiliary power supply diode and an output rectifier diode), and an output capacitor. The flyback transformer includes a primary winding (Np), an auxiliary winding (Na), and a secondary winding (Ns).
[0003] The flyback power supply operates as follows: the input power supplies the primary winding, which is then controlled by the control chip to switch on and off the primary MOSFET. When the primary MOSFET is on, the auxiliary winding Na and the secondary winding Ns are blocked from current due to the presence of the diodes, resulting in energy stored in the primary winding Np. When the primary MOSFET is off, this energy flows through the auxiliary and secondary windings to produce the output voltage. The control chip dynamically adjusts the required secondary voltage using the Vfb voltage generated by the auxiliary winding Na to ensure that the voltage meets the design value.
[0004] As the instruction manual Figure 1 As shown in the figure, the current mainstream solution uses two traditional wire-wound flyback transformers to form two flyback power supplies. Flyback transformer T2 outputs three drive power supplies, Vgd1, Vgd2, and Vgd3, which respectively drive the upper three bridges of the full-bridge drive circuit. Flyback transformer T3 outputs three drive power supplies, Vgd4, Vgd5, and Vgd6, which respectively drive the lower three bridges of the full-bridge drive circuit. Driver power supply Vgd6 is connected to an LDO (low-dropout regulator) to generate the high-voltage sampling auxiliary power supply, Vsens1.
[0005] However, it still has the following disadvantages: 1. Due to the use of two flyback transformers, two sets of peripheral control circuits are required, which is more expensive.
[0006] 2. Because traditional wire-wound flyback transformers are wound on a bobbin, a balance needs to be struck between transformer volume and the number of windings. It is impossible to achieve the characteristics of a large number of windings and a small volume at the same time.
[0007] 3. Due to its structural characteristics, the traditional wound flyback transformer cannot be very low in height, resulting in the inability to further miniaturize the structural size.
[0008] 4. The traditional wound flyback transformer has the problem of difficult control of the winding and frame welding process in production control, which cannot fully realize automated production, increases process costs, and has a high overall price.
[0009] Based on this, the present invention designs a flyback power supply circuit based on a planar transformer to solve the above problems. Summary of the Invention
[0010] In view of the above-mentioned shortcomings of the prior art, the present invention provides a flyback power supply circuit based on a planar transformer.
[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions: A flyback power supply circuit based on a planar transformer has one end of an input capacitor Cin1 connected to the positive terminal of a low-voltage vehicle battery KL30 and the other end grounded. One end of a primary winding Np of a planar transformer T1 is connected to the positive terminal of a low-voltage vehicle battery KL30 and the other end is connected to the drain of a primary-side MOSFET Q1 of a flyback power supply. The source of the primary-side MOSFET Q1 of the flyback power supply is grounded, and the gate is connected to a flyback power supply control chip Flyback IC 1, driven by the flyback power supply control chip Flyback IC 1. One end of an auxiliary winding Na of the planar transformer T1 is connected to the anode of a feedback power supply diode Da1 and the other end is grounded. The cathode of the feedback power supply diode Da1 is connected to the positive terminal of a feedback power supply filter capacitor Cfb1, and the negative terminal of the feedback power supply filter capacitor Cfb1 is grounded, together forming a rectifier and filter circuit that outputs a flyback power supply feedback voltage Vfb1. The cathode of the feedback power supply diode Da1 and the positive terminal of the feedback power supply filter capacitor Cfb1 are connected to the flyback power supply control chip Flyback IC 1, and the flyback power supply feedback voltage Vfb1 signal is transmitted back to the flyback power supply control chip Flyback IC 1; Planar transformer T1 has multiple sets of secondary windings, each set corresponding to one output.
[0012] Furthermore, the planar transformer T1 has seven sets of secondary windings, namely transformer secondary winding Ns1, transformer secondary winding Ns2, transformer secondary winding Ns3, transformer secondary winding Ns4, transformer secondary winding Ns5, transformer secondary winding Ns6 and transformer secondary winding Ns7.
[0013] Furthermore, one end of the secondary winding Ns1 of the transformer is connected to the anode of the output power diode D1, and the other end is grounded; the cathode of the output power diode D1 is connected to the positive electrode of the output power capacitor C1, and the negative electrode of the output power capacitor C1 is grounded, outputting the flyback power supply output voltage Vgd1.
[0014] Furthermore, one end of the secondary winding Ns2 of the transformer is connected to the anode of the output power diode D2, and the other end is grounded; the cathode of the output power diode D2 is connected to the positive electrode of the output power capacitor C2, and the negative electrode of the output power capacitor C2 is grounded, outputting the flyback power supply output voltage Vgd2.
[0015] Furthermore, one end of the secondary winding Ns3 of the transformer is connected to the anode of the output power diode D3, and the other end is grounded; the cathode of the output power diode D3 is connected to the positive electrode of the output power capacitor C3, and the negative electrode of the output power capacitor C3 is grounded, outputting the flyback power supply output voltage Vgd3.
[0016] Furthermore, one end of the secondary winding Ns4 of the transformer is connected to the anode of the output power diode D4, and the other end is grounded; the cathode of the output power diode D4 is connected to the positive electrode of the output power capacitor C4, and the negative electrode of the output power capacitor C4 is grounded, outputting the flyback power supply output voltage Vgd4.
[0017] Furthermore, one end of the secondary winding Ns5 of the transformer is connected to the anode of the output power diode D5, and the other end is grounded; the cathode of the output power diode D5 is connected to the positive electrode of the output power capacitor C5, and the negative electrode of the output power capacitor C5 is grounded, outputting the flyback power supply output voltage Vgd5.
[0018] Furthermore, one end of the secondary winding Ns6 of the transformer is connected to the anode of the output power diode D6, and the other end is grounded; the cathode of the output power diode D6 is connected to the positive electrode of the output power capacitor C6, and the negative electrode of the output power capacitor C6 is grounded, outputting the flyback power supply output voltage Vgd6.
[0019] Furthermore, one end of the secondary winding Ns7 of the transformer is connected to the anode of the output power diode D7, and the other end is grounded; the cathode of the output power diode D7 is connected to the positive electrode of the output power capacitor C7, and the negative electrode of the output power capacitor C7 is grounded, outputting the flyback power supply output voltage Vsens1.
[0020] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts a planar transformer core plus a PCB winding to form a flyback transformer to replace the traditional wound flyback transformer. Since the planar transformer core is assembled on the PCB, there is no winding welding process and the reliability is high.
[0021] The height of the planar transformer core of the present invention is controllable, which can reduce the overall height and volume of components in the driver power circuit, thereby improving power volume density. Furthermore, the planar transformer core can be produced using an automated molding process, which reduces costs and improves quality control.
[0022] The present invention integrates two independent flyback power supplies into one flyback power supply, thereby reducing the number of peripheral control circuit components used and effectively reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.
[0024] Figure 1 This is the circuit diagram of the existing mainstream solution; Figure 2 1 is a circuit diagram of the present invention. DETAILED DESCRIPTION
[0025] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.
[0026] In some embodiments, please refer to the accompanying drawings of the specification. Figure 2 A planar transformer-based flyback power supply circuit uses a planar transformer T1 combined with a wiring winding in a PCB to form a planar transformer solution. The flyback power supply circuit has a total of 8 output power supplies: among them, Vfb1 is used as the primary feedback winding to modulate the power control; Vgd1, Vgd2, Vgd3, Vgd4, Vgd5, and Vgd6 provide drive sources for the upper and lower three bridges of the full-bridge drive circuit; and Vsens1 is used as a high-voltage sampling auxiliary power supply.
[0027] Specifically, the flyback power supply circuit based on the planar transformer includes: The KL30 low-voltage car battery is used to provide 12V low-voltage power to the vehicle. Input capacitor Cin1 is used to provide voltage stabilization, filtering, and energy storage for the flyback power supply input source; Flyback power supply control chip Flyback IC 1 is used to control the power supply operation; The primary side MOSFET Q1 of the flyback power supply is used to act as a switch; Feedback power diode Da1; Output power diodes D1, D2, D3, D4, D5, D6, and D7; Feedback power supply filter capacitor Cfb1; Output power capacitors C1, C2, C3, C4, C5, C6, and C7 serve to store energy and stabilize voltage. Transformer primary winding Np; Transformer auxiliary winding Na; Transformer secondary windings Ns1, Ns2, Ns3, Ns4, Ns5, Ns6 and Ns7; Flyback power supply feedback voltage Vfb1; The flyback power supply output voltages Vgd1, Vgd2, Vgd3, Vgd4, Vgd5 and Vgd6 are used to provide driving power to the back-end driving circuit; The flyback power supply output voltage Vsens1 has the sensor power supply function and can provide a stable working power supply for the back-end sensor.
[0028] One end of the input capacitor Cin1 is connected to the positive terminal of the low-voltage vehicle battery KL30, and the other end is grounded. One end of the primary winding Np of the planar transformer T1 is connected to the positive terminal of the low-voltage vehicle battery KL30 (between the positive terminal of the low-voltage vehicle battery KL30 and the input capacitor Cin1), and the other end is connected to the drain of the primary side MOSFET Q1 of the flyback power supply. The source of the primary side MOSFET Q1 of the flyback power supply is grounded, and the gate is connected to the flyback power supply control chip Flyback IC 1, which is driven by the flyback power supply control chip Flyback IC 1. One end of the auxiliary winding Na of the planar transformer T1 is connected to the anode of the feedback power supply diode Da1, and the other end is grounded. The cathode of the feedback power supply diode Da1 is connected to the positive terminal of the feedback power supply filter capacitor Cfb1, and the negative terminal of the feedback power supply filter capacitor Cfb1 is grounded, together forming a rectifier and filter circuit, which outputs the flyback power supply feedback voltage Vfb1. The cathode of the feedback power supply diode Da1 and the positive terminal of the feedback power supply filter capacitor Cfb1 are connected to the flyback power supply control chip Flyback IC 1. The flyback power supply feedback voltage Vfb1 signal is transmitted back to the flyback power supply control chip Flyback IC 1. The flyback power supply control chip Flyback IC 1 detects the voltage change of the flyback power supply feedback voltage Vfb1 and dynamically adjusts the PWM drive duty cycle of the flyback power supply primary side MOSFET Q1 to achieve output voltage regulation control.
[0029] Planar transformer T1 has 7 sets of secondary windings (transformer secondary windings Ns1, Ns2, Ns3, Ns4, Ns5, Ns6 and Ns7), each corresponding to one output: One end of the secondary winding Ns1 of the transformer is connected to the anode of the output power diode D1, and the other end is grounded; the cathode of the output power diode D1 is connected to the positive electrode of the output power capacitor C1, the negative electrode of the output power capacitor C1 is grounded, and the flyback power supply output voltage Vgd1 is output.
[0030] One end of the secondary winding Ns2 of the transformer is connected to the anode of the output power diode D2, and the other end is grounded; the cathode of the output power diode D2 is connected to the positive electrode of the output power capacitor C2, the negative electrode of the output power capacitor C2 is grounded, and the output flyback power supply output voltage Vgd2 is output.
[0031] One end of the secondary winding Ns3 of the transformer is connected to the anode of the output power diode D3, and the other end is grounded; the cathode of the output power diode D3 is connected to the positive electrode of the output power capacitor C3, the negative electrode of the output power capacitor C3 is grounded, and the flyback power supply output voltage Vgd3 is output.
[0032] One end of the secondary winding Ns4 of the transformer is connected to the anode of the output power diode D4, and the other end is grounded; the cathode of the output power diode D4 is connected to the positive electrode of the output power capacitor C4, the negative electrode of the output power capacitor C4 is grounded, and the flyback power supply output voltage Vgd4 is output.
[0033] One end of the secondary winding Ns5 of the transformer is connected to the anode of the output power diode D5, and the other end is grounded; the cathode of the output power diode D5 is connected to the positive electrode of the output power capacitor C5, the negative electrode of the output power capacitor C5 is grounded, and the output flyback power supply output voltage Vgd5 is output.
[0034] One end of the secondary winding Ns6 of the transformer is connected to the anode of the output power diode D6, and the other end is grounded; the cathode of the output power diode D6 is connected to the positive electrode of the output power capacitor C6, the negative electrode of the output power capacitor C6 is grounded, and the output flyback power supply output voltage Vgd6 is output.
[0035] One end of the secondary winding Ns7 of the transformer is connected to the anode of the output power diode D7, and the other end is grounded; the cathode of the output power diode D7 is connected to the positive electrode of the output power capacitor C7, the negative electrode of the output power capacitor C7 is grounded, and the flyback power supply output voltage Vsens1 is output.
[0036] The present invention adopts a planar transformer core and a PCB winding to form a flyback transformer to replace a traditional wound flyback transformer. Since the planar transformer core is assembled on the PCB, no winding welding process is required, and the reliability is high.
[0037] The height of the planar transformer core of the present invention is controllable, which can reduce the overall height and volume of components in the driver power circuit, thereby improving power volume density. Furthermore, the planar transformer core can be produced using an automated molding process, which reduces costs and improves quality control.
[0038] The present invention integrates two independent flyback power supplies into one flyback power supply, thereby reducing the number of peripheral control circuit components used and effectively reducing costs.
[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.
Claims
1. A flyback power supply circuit based on a planar transformer, characterized in that: One end of the input capacitor Cin1 is connected to the positive terminal of the low-voltage vehicle battery KL30, and the other end is grounded. One end of the primary winding Np of the planar transformer T1 is connected to the positive terminal of the low-voltage vehicle battery KL30, and the other end is connected to the drain of the primary side MOSFET Q1 of the flyback power supply. The source of the primary side MOSFET Q1 of the flyback power supply is grounded, and the gate is connected to the flyback power supply control chip Flyback IC 1, which is driven by the flyback power supply control chip Flyback IC 1. One end of the auxiliary winding Na of the planar transformer T1 is connected to the anode of the feedback power supply diode Da1, and the other end is grounded. The cathode of the feedback power supply diode Da1 is connected to the positive terminal of the feedback power supply filter capacitor Cfb1, and the negative terminal of the feedback power supply filter capacitor Cfb1 is grounded, together forming a rectifier and filter circuit, which outputs the flyback power supply feedback voltage Vfb1. The cathode of the feedback power supply diode Da1 and the positive terminal of the feedback power supply filter capacitor Cfb1 are connected to the flyback power supply control chip Flyback IC 1, and the flyback power supply feedback voltage Vfb1 signal is transmitted back to the flyback power supply control chip Flyback IC 1; Planar transformer T1 has multiple sets of secondary windings, each set corresponding to one output.
2. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: The planar transformer T1 has seven sets of secondary windings, namely, transformer secondary winding Ns1, transformer secondary winding Ns2, transformer secondary winding Ns3, transformer secondary winding Ns4, transformer secondary winding Ns5, transformer secondary winding Ns6 and transformer secondary winding Ns7.
3. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: One end of the secondary winding Ns1 of the transformer is connected to the anode of the output power diode D1, and the other end is grounded; the cathode of the output power diode D1 is connected to the positive electrode of the output power capacitor C1, the negative electrode of the output power capacitor C1 is grounded, and the flyback power supply output voltage Vgd1 is output.
4. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: One end of the secondary winding Ns2 of the transformer is connected to the anode of the output power diode D2, and the other end is grounded; the cathode of the output power diode D2 is connected to the positive electrode of the output power capacitor C2, the negative electrode of the output power capacitor C2 is grounded, and the output flyback power supply output voltage Vgd2 is output.
5. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: One end of the secondary winding Ns3 of the transformer is connected to the anode of the output power diode D3, and the other end is grounded; the cathode of the output power diode D3 is connected to the positive electrode of the output power capacitor C3, the negative electrode of the output power capacitor C3 is grounded, and the flyback power supply output voltage Vgd3 is output.
6. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: One end of the secondary winding Ns4 of the transformer is connected to the anode of the output power diode D4, and the other end is grounded; the cathode of the output power diode D4 is connected to the positive electrode of the output power capacitor C4, the negative electrode of the output power capacitor C4 is grounded, and the flyback power supply output voltage Vgd4 is output.
7. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: One end of the secondary winding Ns5 of the transformer is connected to the anode of the output power diode D5, and the other end is grounded; the cathode of the output power diode D5 is connected to the positive electrode of the output power capacitor C5, the negative electrode of the output power capacitor C5 is grounded, and the output flyback power supply output voltage Vgd5 is output.
8. The flyback power supply circuit based on a planar transformer according to claim 1, characterized in that: One end of the secondary winding Ns6 of the transformer is connected to the anode of the output power diode D6, and the other end is grounded; the cathode of the output power diode D6 is connected to the positive electrode of the output power capacitor C6, the negative electrode of the output power capacitor C6 is grounded, and the output flyback power supply output voltage Vgd6 is output.
9. The flyback power supply circuit based on a planar transformer according to any one of claims 1 to 8, characterized in that: One end of the secondary winding Ns7 of the transformer is connected to the anode of the output power diode D7, and the other end is grounded; the cathode of the output power diode D7 is connected to the positive electrode of the output power capacitor C7, the negative electrode of the output power capacitor C7 is grounded, and the flyback power supply output voltage Vsens1 is output.
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