Winding multiplexing flyback circuit
By using a flyback circuit with winding reuse, the second primary winding of the main power winding of the flyback switching power supply is reused as the VCC auxiliary power supply winding, which solves the problem of insufficient transformer bobbin pins and achieves a reduction in transformer size and cost.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-17
- Publication Date
- 2026-04-03
AI Technical Summary
In existing technologies, the insufficient number of pins in the transformer frame of high-frequency switching power supplies prevents the transformer size from being reduced, thus increasing the space occupied and R&D costs of the switching power supply.
By adopting a winding reuse flyback circuit, part of the second primary winding of the main power winding of the flyback switching power supply is reused as the VCC auxiliary power supply winding, which reduces the number of bobbin pins, shrinks the bobbin size, and solves the problem of coil fullness when winding the transformer.
It effectively reduces the number of transformer pins and volume, lowers the cost of high-frequency transformers, and simultaneously achieves the functions of traditional flyback converters.
Smart Images
Figure CN224083420U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of electronic circuit technology, and specifically relates to a winding multiplexing flyback circuit. Background Technology
[0002] Currently, the development trend of switching power supplies is towards higher frequencies and smaller sizes. However, the development of higher frequencies brings EMI performance issues. To solve these EMI problems, the industry usually uses a "sandwich" winding method for transformers, dividing the primary winding into at least two windings and winding a secondary winding in a sandwich structure. Figure 2 This winding method requires the transformer bobbin to have a sufficient number of pins for wire insertion into the PCB board. In switching power supplies, the high-frequency transformer is a crucial component; its size and volume determine the overall size of the power supply. The transformer's power rating is related to the coil current carrying capacity, the bobbin's specifications, and the core's specifications. Therefore, reducing the transformer's size within the same power rating is critical. Currently, if the existing bobbin doesn't have enough pins, the only solution is to modify the bobbin size, increasing the number of pins, which inevitably increases the transformer's size. This increased transformer size leads to wasted space in the switching power supply and a larger PCB area. This contradicts the miniaturization trend of switching power supplies and significantly increases R&D costs. Utility Model Content
[0003] This invention aims to overcome the problems of insufficient skeleton pins and inability to reduce transformer size in the prior art, and provides a winding multiplexing flyback circuit to solve the pain point of insufficient skeleton pins in transformers using the "sandwich" winding method to optimize EMI performance in the industry.
[0004] To achieve the above objectives, the present invention adopts the following technical solution:
[0005] This utility model embodiment provides a winding multiplexed flyback circuit, including an energy storage unit, a main control unit, a switching unit, a VCC power supply unit, a sampling unit, a high-frequency transformer unit, and a rectifier output unit;
[0006] The first end of the energy storage unit is connected to the positive input port and the opposite end of the first primary winding of the high-frequency transformer. The same end of the first primary winding is connected to the first end of the switching unit. The second end of the switching unit is connected to the first end of the sampling unit and the first end of the main control unit. The second end of the sampling unit is connected to the opposite end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit. The same end of the second primary winding is connected to the negative input port, the second end of the energy storage unit, and the second end of the VCC power supply unit. The same end of the secondary winding of the high-frequency transformer unit is connected to the first end of the rectifier output unit. The opposite end of the secondary winding is connected to the second end of the rectifier output unit. The output end of the VCC power supply unit is connected to the input end of the main control unit. The output end of the main control unit is connected to the control end of the switching unit.
[0007] Optionally, the energy storage unit includes a first capacitor, the first end of which is connected to the positive input port and the opposite end of the first primary winding, and the second end of the energy storage unit is connected to the negative input port, the same end of the second primary winding, and the second end of the VCC power supply unit.
[0008] Optionally, the main control unit includes a control chip, the CS sampling pin of the control chip is connected to the second terminal of the switching unit and the first terminal of the sampling unit respectively, the power supply pin of the control chip is connected to the output terminal of the VCC power supply unit, the drive pin of the control chip is connected to the control terminal of the switching unit, and the IC ground pin of the control chip is connected to the ground terminal.
[0009] Optionally, the switching unit includes a first switching transistor, the first end of which is connected to the same-named end of the first primary winding, the second end of which is connected to the first end of the sampling unit and the first end of the main control unit, and the control end of the first switching transistor is connected to the output end of the main control unit.
[0010] Optionally, the sampling unit includes a first resistor, the first end of which is connected to the second end of the switching unit and the first end of the main control unit, and the second end of which is connected to the opposite end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit.
[0011] Optionally, the VCC power supply unit includes a first diode and a second capacitor. The first terminal of the second capacitor is connected to the opposite terminal of the second primary winding and the second terminal of the sampling unit, respectively. The anode of the first diode is connected to the negative input port, the second terminal of the energy storage unit and the same terminal of the second primary winding, respectively. The cathode of the first diode is connected to the second terminal of the second capacitor and the input terminal of the main control unit, respectively.
[0012] Optionally, the rectifier output unit includes a second diode and a third capacitor. The anode of the second diode is connected to the same-name terminal of the secondary winding, and the cathode of the second diode is connected to the opposite-name terminal of the secondary winding through the third capacitor. The positive terminal of the third capacitor is connected to the positive output port, and the negative terminal of the third capacitor is connected to the negative output port.
[0013] Optionally, the sampling unit includes a current transformer, the first end of which is connected to the second end of the switching unit and the first end of the main control unit, and the second end of which is connected to the opposite end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit.
[0014] Optionally, the main control unit includes a microcontroller, the sampling terminal of the microcontroller is connected to the second terminal of the switching unit and the first terminal of the sampling unit respectively, the power supply terminal of the microcontroller is connected to the output terminal of the VCC power supply unit, the driving terminal of the microcontroller is connected to the control terminal of the switching unit, and the grounding terminal pin of the microcontroller is connected to the ground terminal.
[0015] Compared with the prior art, this utility model has the following advantages and beneficial effects:
[0016] This invention reuses a portion of the second primary winding of the main power winding of the flyback switching power supply as a VCC auxiliary power supply winding, which can effectively reduce the number of pins in the frame, thereby reducing the frame size. At the same time, eliminating one VCC winding can also solve the problem of coil fullness during transformer winding, thus reducing the cost of high-frequency transformers. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of a winding multiplexing flyback circuit according to the present invention.
[0018] Figure 2 This is a circuit schematic diagram of a conventional sandwich-wound flyback converter in the prior art;
[0019] Figure 3 This is a circuit diagram of a winding multiplexing flyback circuit according to the present invention. Detailed Implementation
[0020] The present invention and its beneficial effects will be further described in detail below with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this application.
[0021] It should be noted that the terms "comprising" and "having" and any variations thereof described in the specification and claims of this application are intended to cover non-exclusive inclusion. For example, including a series of components, unit circuits or control timings is not necessarily limited to those components, unit circuits or control timings that are explicitly listed, but may include components, unit circuits or control timings that are not explicitly listed or that are inherent to these circuits.
[0022] Furthermore, unless otherwise specified, the embodiments and features described in this application may be combined with each other.
[0023] It should be understood that, in the specification and claims, when an element is described as being “connected” to another element, that element may be “directly connected” to the other element or “connected” to the other element via a third element.
[0024] refer to Figure 1 This utility model provides a winding multiplexed flyback circuit, including an energy storage unit, a main control unit, a switching unit, a VCC power supply unit, a sampling unit, a high-frequency transformer unit, and a rectifier output unit;
[0025] The first end of the energy storage unit is connected to the positive input port and the opposite end of the first primary winding of the high-frequency transformer. The same end of the first primary winding is connected to the first end of the switching unit. The second end of the switching unit is connected to the first end of the sampling unit and the first end of the main control unit. The second end of the sampling unit is connected to the opposite end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit. The same end of the second primary winding is connected to the negative input port, the second end of the energy storage unit, and the second end of the VCC power supply unit. The same end of the secondary winding of the high-frequency transformer unit is connected to the first end of the rectifier output unit. The opposite end of the secondary winding is connected to the second end of the rectifier output unit. The output end of the VCC power supply unit is connected to the input end of the main control unit. The output end of the main control unit is connected to the control end of the switching unit.
[0026] In the first embodiment, the energy storage unit is a first capacitor C1, the main control unit is a control chip U1, the switching unit is a first switching transistor Q1, and the first switching transistor can be implemented using switching devices such as MOS transistors, field-effect transistors or transistors. In this embodiment, the first switching transistor is an NMOS transistor; the sampling unit is a first resistor R1, the VCC power supply unit includes a first diode D1 and a second capacitor C2, and the rectifier output unit includes a second diode D2 and a third capacitor C3.
[0027] See Figure 3 The connection method is as follows: the positive input port VIN+ is connected to the positive terminal of the first capacitor C1 and the opposite terminal of the first primary winding S1 of the high-frequency transformer; the same terminal of the first primary winding S1 is connected to the drain of the first switching transistor Q1; the source of the first switching transistor Q1 is connected to one end of the first resistor R1 and the CS sampling pin of the control chip U1; the other end of the first resistor R1 is connected to the ground pin of the control chip U1, the negative terminal of the second capacitor C2, and the opposite terminal of the second primary winding of the high-frequency transformer; the same terminal of the second primary winding of the high-frequency transformer is connected to the first diode D1 of the VCC power supply unit. The anode and the negative terminal of the first capacitor C1, as well as the VIN- of the input port, are connected. The cathode of the first diode D1 of the VCC power supply unit is connected to the positive terminal of the second capacitor C2, and at the same time, it is connected to the VCC power supply pin of the control chip U1. The PWM drive pin of the control chip U1 is connected to the gate of the first switching transistor Q1. The same-name terminal of the secondary winding S3 of the high-frequency transformer is connected to the anode of the second diode D2. The cathode of the second diode D2 is connected to the positive terminal of the third capacitor C3 and the positive output port VOUT+. The opposite-name terminal of the secondary winding S3 is connected to the negative terminal of the third capacitor C3 and the negative output port VOUT-.
[0028] The working principle of this embodiment is as follows: When the circuit is working normally, the second capacitor C2 supplies power to the control chip U1. The control chip U1, through the voltage of the first resistor R1, controls the output of a PWM wave to control the on and off of the first switching transistor Q1. When the PWM wave output by U1 is high, the first primary winding S1 and the second primary winding S2 are energized and store energy. When the PWM wave output by U1 is low, the polarity of the first primary winding S1 and the second primary winding S2 changes, and the stored energy is transferred to the secondary side for demagnetization. At the same time, the second capacitor C2 is charged. The turns ratio of the first primary winding S1 and the second primary winding S2 is determined by the output voltage of the secondary side of the winding and the supply voltage of U1 during normal operation. This utility model patent can achieve the function of a traditional flyback converter while reducing one VCC winding. It can solve the problem that the high-frequency transformer is wound too full to accommodate the magnetic core. At the same time, it can reduce two transformer pins, reduce the transformer size, and reduce the transformer cost.
[0029] Second embodiment:
[0030] The second embodiment is based on the first embodiment. The first resistor R1 can be replaced with a current transformer for sampling, the control unit can be replaced with a microcontroller, and the secondary diode rectification can be replaced with synchronous rectification. Its working principle is similar to that of the first embodiment, and will not be described here.
[0031] The above-described embodiments of this utility model are merely illustrative examples and not intended to limit the implementation of this utility model. Those skilled in the art can make other variations and modifications based on the above description. It is impossible to exhaustively list all possible implementations here. All obvious variations or modifications derived from the technical solutions of this utility model are still within the protection scope of this utility model.
Claims
1. A winding multiplex flyback circuit, characterized by: The winding multiplex flyback circuit comprises an energy storage unit, a main control unit, a switching unit, a VCC power supply unit, a sampling unit, a high-frequency transformer unit and a rectification output unit; The first end of the energy storage unit is connected to the positive input port and the opposite-phase end of the first primary winding of the high-frequency transformer respectively, the same-phase end of the first primary winding is connected to the first end of the switching unit, the second end of the switching unit is connected to the first end of the main control unit and the first end of the sampling unit respectively, the second end of the sampling unit is connected to the opposite-phase end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit respectively, the same-phase end of the second primary winding is connected to the negative input port, the second end of the energy storage unit and the second end of the VCC power supply unit respectively, the same-phase end of the secondary winding of the high-frequency transformer unit is connected to the first end of the rectification output unit, the opposite-phase end of the secondary winding is connected to the second end of the rectification output unit, the output end of the VCC power supply unit is connected to the input end of the main control unit, and the output end of the main control unit is connected to the control end of the switching unit.
2. A winding multiplex flyback circuit according to claim 1, characterized in that: The energy storage unit comprises a first capacitor, and the first end of the first capacitor is connected to the positive input port and the opposite-phase end of the first primary winding respectively, and the second end of the energy storage unit is connected to the negative input port, the same-phase end of the second primary winding and the second end of the VCC power supply unit respectively.
3. The winding multiplex flyback circuit of claim 1, wherein: The main control unit comprises a control chip, the CS sampling pin of the control chip is connected to the second end of the switching unit and the first end of the sampling unit respectively, the power supply pin of the control chip is connected to the output end of the VCC power supply unit, the driving pin of the control chip is connected to the control end of the switching unit, and the IC ground pin of the control chip is connected to the ground end.
4. The winding multiplex flyback circuit of claim 1, wherein: The switching unit comprises a first switch tube, the first end of the first switch tube is connected to the same-phase end of the first primary winding, the second end of the first switch tube is connected to the first end of the main control unit and the first end of the sampling unit respectively, and the control end of the first switch tube is connected to the output end of the main control unit.
5. The winding multiplex flyback circuit of claim 1, wherein: The sampling unit comprises a first resistor, the first end of the first resistor is connected to the second end of the switching unit and the first end of the main control unit respectively, and the second end of the first resistor is connected to the opposite-phase end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit respectively.
6. The winding multiplex flyback circuit of claim 1, wherein: The VCC power supply unit comprises a first diode and a second capacitor, the first end of the second capacitor is connected to the opposite-phase end of the second primary winding and the second end of the sampling unit respectively, the anode of the first diode is connected to the negative input port, the second end of the energy storage unit and the same-phase end of the second primary winding respectively, and the cathode of the first diode is connected to the second end of the second capacitor and the input end of the main control unit respectively.
7. The winding multiplex flyback circuit of claim 1, wherein: The rectification output unit comprises a second diode and a third capacitor, an anode of the second diode is connected to the same end of the secondary winding, a cathode of the second diode is connected to the different end of the secondary winding through the third capacitor, a positive pole of the third capacitor is connected to the positive output port, and a negative pole of the third capacitor is connected to the negative output port.
8. The winding multiplex flyback circuit of claim 1, wherein: The sampling unit comprises a current transformer, first ends of the current transformer are connected to the second ends of the switch units and the first end of the main control unit respectively, and second ends of the current transformer are connected to the different end of the second primary winding of the high-frequency transformer unit and the first end of the VCC power supply unit respectively.
9. The winding multiplex flyback circuit of claim 1, wherein: The main control unit comprises a single-chip microcomputer, sampling ends of the single-chip microcomputer are connected to the second ends of the switch units and the first end of the sampling unit respectively, a power supply end of the single-chip microcomputer is connected to the output end of the VCC power supply unit, a driving end of the single-chip microcomputer is connected to the control end of the switch unit, and a grounding end pin of the single-chip microcomputer is connected to the ground end.