Parallel automatic current sharing circuit based on PCB

Abstract

The utility model relates to the technical field of power supply circuits, in particular to a parallel automatic current-sharing circuit based on a PCB (Printed Circuit Board), which comprises a first current-sharing branch and a second current-sharing branch which are symmetrically designed in parallel, and each of the first current-sharing branch and the second current-sharing branch comprises an independent winding transformer. One end of the output side of the independent winding transformer is connected with the drain electrode of the third switching power MOS tube and the source electrode of the first switching power MOS tube, the other end of the output side of the independent winding transformer is connected with the source electrode of the second switching power MOS tube and the drain electrode of the fourth switching power MOS tube, and the source electrode of the third switching power MOS tube and the source electrode of the fourth switching power MOS tube are both connected with the negative electrode output end. The drain electrode of the first switch power MOS tube and the drain electrode of the second switch power MOS tube are connected with the input end of the power inductor. And one end of the first capacitor is connected with the source electrode of the third switch power MOS tube in the second current-sharing branch, and the other end of the first capacitor is connected with the output end of the power inductor in the first current-sharing branch. The utility model aims to provide the parallel automatic current sharing circuit which is low in cost, good in current sharing effect and high in stability.

Description

Technical Field

[0001] The utility model relates to the technical field of power supply circuits, and particularly relates to a parallel automatic current sharing circuit based on a PCB board. Background Technique

[0002] With the continuous development of our society, the continuous advancement of the modernization process, the continuous improvement of the economy and science and technology, the power electronics technology has also achieved rapid development, and the power electronics equipment has penetrated into people's daily work and life, and the relationship has become increasingly close. And power electronics equipment often requires a power supply as a power device. In the 1980s, the computer power supply first completed the replacement and fully realized the switching power supply; in the 1990s, the switching power supply gradually entered various electronic fields and was widely used, accelerating the development of its technology.

[0003] At present, the overall development trend of medium and small power switching power supplies begins to develop from the whole to the modular, from low frequency to high frequency, and from high energy consumption to low energy consumption. For the development of power supply modularization, fixed-size brick-shaped modules have been formed in the industry, such as full-brick modules, half-brick modules, 1 / 4-brick module power supplies, etc.

[0004] In recent years, the development of electronic technology has made the working voltage of the circuit lower and lower and the current higher and higher. Low-voltage operation is beneficial to reducing the overall power loss of the circuit, but it also poses new problems for power supply design: the output filter capacitor is too large in volume in high-current application scenarios, and the device current stress and conduction loss are large; two-phase interleaved parallel connection can greatly reduce the output current ripple and reduce the output capacitor volume. Classifying the parallel system from the mechanism of current sharing, it can be roughly divided into two categories, namely the step-down method and the active current sharing method.

[0005] Step-down method: The idea of the step-down method is mainly that if the current of a certain module is too large, its voltage is lowered to ensure the balance of its output power. The working mechanism of the step-down method adjusts the output impedance to achieve current sharing between converters. Generally speaking, the larger the current sharing, the worse the voltage regulation of the converter. Generally, the power supply is designed to have a low output impedance to obtain good voltage regulation characteristics, so it cannot achieve good automatic current sharing. The disadvantage is that an output impedance adjustment circuit needs to be added, which increases the circuit complexity and increases the hardware cost.

[0006] Active current sharing method: The active current sharing method adjusts through a specific control structure and current programming in combination with an external controller. The external controller is the main device used to achieve current sharing. The external regulator compares the current sharing signals of each load unit and then adjusts the corresponding feedback voltage to achieve load balancing. This method has good adjustment performance, but it requires an additional controller, connections between multiple controllers, and separate power supply for the controller. In addition, using an additional controller to coordinate the operation of each power supply affects the reliability of the system to a certain extent. The disadvantages of the active current sharing method are complex design, difficult control, low efficiency, easy to cause system instability, and increased design cost. Utility Model Content

[0007] The purpose of the present utility model is to provide a parallel automatic current sharing circuit based on a PCB board to solve the technical problems of the existing parallel current sharing circuit in the background technology, such as complex design, high cost, and easy to affect system stability.

[0008] To achieve the above purpose, the present utility model provides a parallel automatic current sharing circuit based on a PCB board. The parallel automatic current sharing circuit is arranged on the PCB board and includes a first current sharing branch and a second current sharing branch. The first current sharing branch and the second current sharing branch are designed symmetrically in parallel, where:

[0009] Both the first current sharing branch and the second current sharing branch include an independent winding transformer. One end of the output side of the independent winding transformer is connected to the drain of the third switching power MOS tube and the source of the first switching power MOS tube, and one end is connected to the source of the second switching power MOS tube and the drain of the fourth switching power MOS tube. The sources of the third switching power MOS tube and the fourth switching power MOS tube are both connected to the negative output terminal. The drains of the first switching power MOS tube and the second switching power MOS tube are both connected to the input end of the power inductor. The output end of the power inductor is connected to the positive output terminal;

[0010] It also includes a first capacitor. One end of the first capacitor is connected to the sources of the third switching power MOS tube and the fourth switching power MOS tube in the second current sharing branch, and the other end is connected to the output end of the power inductor in the first current sharing branch and the output end of the power inductor in the second current sharing branch.

[0011] Further, the input side and the output side are electrically isolated through the independent winding transformer, and the high voltage on the input side is converted into a low voltage and large current on the output side.

[0012] Further, the input side winding and the output side winding of the independent winding transformer adopt a multi-layer design.

[0013] Further, both the first current-sharing branch and the second current-sharing branch include a second capacitor. One end of the second capacitor is connected to the drains of the first switching power MOS transistor, the second switching power MOS transistor and the power inductor, and the other end is connected to the sources of the third switching power MOS transistor and the fourth switching power MOS transistor.

[0014] Further, the PCB board uses a thick-layer board, and the inner layer of the PCB board is copper-clad.

[0015] The beneficial effects of the present utility model include:

[0016] 1. By using a PCB planar transformer and a PCB inductor, compared with traditional transformers, there is no need for a winding skeleton, which can reduce the volume of the transformer and the cost. The PCB winding is in the form of planar copper sheets, which has excellent heat dissipation. The PCB winding adopts a multi-layer design. The input-side winding and the output-side winding of the transformer adopt a sandwich structure, and the windings of the transformer are fully coupled, reducing the leakage inductance. Between layers, it can meet the high withstand voltage requirements of the transformer.

[0017] 2. The PCB uses a thick-layer board, and the inner layer also uses a large area of copper cladding, making the internal resistance of the PCB traces small, reducing the power loss on the line during operation, and having higher stability during operation. The two windings on the output side of the transformer and the winding of the power inductor use a completely symmetric wiring method, making the internal resistances of the two parallel windings exactly the same and the currents the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required to be used in the embodiments of the present utility model. It should be understood that the following drawings only show some embodiments of the present utility model, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0019] Figure 1 FIG. is a schematic diagram of a parallel automatic current-sharing circuit based on a PCB board provided for an embodiment of the present utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The following will describe the technical solutions in the embodiments of the present utility model with reference to the drawings in the embodiments of the present utility model.

[0021] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. It should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the utility model product is usually placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present application. In addition, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0022] Please refer to Figure 1 As shown, a parallel automatic current sharing circuit based on a PCB board provided by at least one embodiment of the present disclosure is disposed on the PCB board and includes a first current sharing branch and a second current sharing branch. The first current sharing branch is in parallel with the second current sharing branch, where:

[0023] The first current sharing branch includes an independent winding transformer T1. One end of the output side of the independent winding transformer T1 is connected to the drain of the switching power MOS transistor S3 and the source of the switching power MOS transistor S1, and the other end is connected to the source of the switching power MOS transistor S2 and the drain of the switching power MOS transistor S4. The drain of the switching power MOS transistor S1 is connected to the drain of the switching power MOS transistor S2, and the source of the switching power MOS transistor S3 is connected to the source of the switching power MOS transistor S4. The source of the switching power MOS transistor S3 and the source of the switching power MOS transistor S4 are connected to the negative output terminal, and the drain of the switching power MOS transistor S1 and the drain of the switching power MOS transistor S2 are connected to the input terminal of the power inductor L1. The output terminal of the power inductor L1 is connected to the positive output terminal;

[0024] The second current sharing branch includes an independent winding transformer T2. One end of the output side of the independent winding transformer T2 is connected to the drain of the switching power MOS transistor S7 and the source of the switching power MOS transistor S5, and the other end is connected to the source of the switching power MOS transistor S6 and the drain of the switching power MOS transistor S8. The drain of the switching power MOS transistor S5 is connected to the drain of the switching power MOS transistor S6, and the source of the switching power MOS transistor S7 is connected to the source of the switching power MOS transistor S8. The source of the switching power MOS transistor S7 and the source of the switching power MOS transistor S8 are connected to the negative output terminal, and the drain of the switching power MOS transistor S5 and the drain of the switching power MOS transistor S6 are connected to the input terminal of the power inductor L2. The output terminal of the power inductor L2 is connected to the positive output terminal;

[0025] In this embodiment, the independent transformer electrically isolates the input side and the output side. The two independent transformers convert the high voltage on the input side into a low voltage and large current on the output side by controlling the turns ratio. The output side of the transformer uses two independent windings in parallel. The switching power MOS transistors conduct alternately to generate a pulsed voltage. By controlling the duty cycle of the pulsed voltage, the pulsed voltage passes through the power inductor and the output filter capacitor to make the output reach the required stable low voltage.

[0026] Specifically, the high voltage on the input side is converted into a low voltage and large current on the output side through two independent transformers. The large output current uses two sets of coils in parallel. If the current in the two sets of coils is not evenly divided, it will cause the winding with more overcurrent to heat up severely, easily leading to device damage and unstable system operation. In this embodiment, a multi-layer PCB is used in combination with the PCB planar transformer technology, with symmetrical layout and large-area copper plating, which can achieve the internal resistance matching of multiple windings and achieve the effect of automatic current sharing.

[0027] Specifically, in this embodiment, the input side windings and the output side windings of the independent winding transformer T1 and the independent winding transformer T2 both adopt a multi-layer design, enabling full coupling between the transformer windings and reducing the leakage inductance. Between layers, the high voltage withstand requirement of the transformer can be met.

[0028] It also includes a capacitor C1. One end of the capacitor C1 is connected to the source electrodes of the switching power MOS transistors S7 and S8, and the other end is connected to the output ends of the power inductors L1 and L2.

[0029] Specifically, in this embodiment, it also includes a capacitor C2. The capacitor C2 is arranged on the first current sharing branch. One end of it is connected to the input side of the power inductor L1, and one end is connected to the negative output terminal; there is a capacitor C3 symmetrically arranged with the capacitor C2 on the second current sharing branch. One end of it is connected to the input side of the power inductor L2, and one end is connected to the negative output terminal.

[0030] As described above, the above is only the specific implementation manner of the present utility model, but the protection scope of the present utility model is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present utility model can easily think of changes or substitutions, which should all be covered within the protection scope of the present utility model. Therefore, the protection scope of the present utility model shall be subject to the protection scope of the claims.

Claims

1. A parallel automatic current sharing circuit based on a PCB board, the parallel automatic current sharing circuit being disposed on the PCB board, characterized in that, It includes a first current sharing branch and a second current sharing branch, and the first current sharing branch and the second current sharing branch are designed symmetrically in parallel, where: Both the first current sharing branch and the second current sharing branch include an independent winding transformer. One end of the output side of the independent winding transformer is connected to the drain of the third switching power MOS tube and the source of the first switching power MOS tube, and the other end is connected to the source of the second switching power MOS tube and the drain of the fourth switching power MOS tube. The sources of the third switching power MOS tube and the fourth switching power MOS tube are both connected to the negative output terminal, and the drains of the first switching power MOS tube and the second switching power MOS tube are both connected to the input terminal of the power inductor. The output terminal of the power inductor is connected to the positive output terminal; It further includes a first capacitor. One end of the first capacitor is connected to the sources of the third switching power MOS tube and the fourth switching power MOS tube in the second current sharing branch, and the other end is connected to the output terminal of the power inductor in the first current sharing branch and the output terminal of the power inductor in the second current sharing branch.

2. The parallel automatic current sharing circuit based on a PCB board according to claim 1, wherein The input side and the output side are electrically isolated through the independent winding transformer, and the high voltage on the input side is converted into a low voltage and large current on the output side.

3. A parallel automatic current sharing circuit based on a PCB board according to claim 1, characterized in that, The input side winding and the output side winding of the independent winding transformer adopt a multi-layer design.

4. A parallel automatic current sharing circuit based on a PCB board according to claim 1, characterized in that, Both the first current sharing branch and the second current sharing branch include a second capacitor. One end of the second capacitor is connected to the drains of the first switching power MOS tube and the second switching power MOS tube and the power inductor, and the other end is connected to the sources of the third switching power MOS tube and the fourth switching power MOS tube.

5. A parallel automatic current sharing circuit based on a PCB board according to claim 1, characterized in that, The PCB board uses a thick layer board, and the inner layer of the PCB board is copper-clad.

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