阅读说明：本技术 一种并联均流的反激变换器 (Flyback converter with parallel current sharing ) 是由 张艺蒙 孙世凯 郭辉 宋庆文 汤晓燕 张玉明 于 2021-07-09 设计创作，主要内容包括：本发明公开了一种并联均流的反激变换器,包括：反激电路和并联均流电路；其中,所述并联均流电路包括多个并联的支路,每个支路包括串接的功率器件和电感；每个支路均串接于所述反激电路的副边电路中,所有支路的电感缠绕于同一磁芯上以彼此耦合。本发明解决了开关电源因并联功率器件分担电流不均导致的导通电阻过大、散热不均的问题,提升了高功率密度下开关电源的性能和寿命。(The invention discloses a flyback converter with parallel current sharing, which comprises: a flyback circuit and a parallel current-sharing circuit; the parallel current-sharing circuit comprises a plurality of parallel branches, and each branch comprises a power device and an inductor which are connected in series; each branch circuit is connected in series in a secondary side circuit of the flyback circuit, and the inductors of all the branch circuits are wound on the same magnetic core to be coupled with each other. The invention solves the problems of overlarge on-resistance and uneven heat dissipation of the switching power supply caused by uneven current sharing of the parallel power devices, and improves the performance and the service life of the switching power supply under high power density.)

1. A parallel current sharing flyback converter, comprising: a flyback circuit and a parallel current-sharing circuit;

the parallel current-sharing circuit comprises a plurality of parallel branches, and each branch comprises a power device and an inductor which are connected in series; each branch circuit is connected in series in a secondary side circuit of the flyback circuit, and the inductors of all the branch circuits are wound on the same magnetic core to be coupled with each other.

2. The flyback converter of claim 1 wherein the secondary circuit includes one winding; and the plurality of parallel branches are connected with the winding in series.

3. A flyback converter as in claim 1 wherein the secondary circuit comprises a plurality of windings in parallel relationship, each winding being connected in series with one of the legs.

4. The flyback converter of claim 1 wherein the secondary side circuit includes a plurality of windings in parallel relationship, any winding being connected in series with one or more of the legs.

5. The flyback converter of claim 1 wherein the power device comprises: and a rectifying diode.

6. The flyback converter of claim 1 wherein the power device comprises: an N-type MOSFET or ideal diode;

the N-type MOSFET or the ideal diode is connected in series in the branch circuit through a source electrode and a drain electrode.

7. The flyback converter of claim 1 wherein the flyback circuit comprises: RCDs passive clamps, or active clamp quasi-resonant converters.

Technical Field

The invention belongs to the technical field of power electronics, and particularly relates to a flyback converter with parallel current sharing.

Background

With the power density of the switching power supply being higher and higher, the output current of the switching power supply is larger and larger. With the increase of the switching current, a single power device is difficult to meet the current capability and the heat dissipation requirement, and a plurality of power devices are often required to be connected in parallel in the switching power supply.

When power devices are connected in parallel, due to the problems of inconsistency of the power devices, circuit layout, time delay of a driving circuit and the like, the current shared by the power devices connected in parallel is often uneven, so that various adverse consequences are caused, including the problems of overlarge on-resistance, uneven heat dissipation and the like of a switching power supply, and the service life of the power device with larger current is also influenced when the power device is serious.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a flyback converter with parallel current sharing.

The technical problem to be solved by the invention is realized by the following technical scheme:

a parallel current sharing flyback converter, comprising: a flyback circuit and a parallel current-sharing circuit;

the parallel current-sharing circuit comprises a plurality of parallel branches, and each branch comprises a power device and an inductor which are connected in series; each branch circuit is connected in series in a secondary side circuit of the flyback circuit, and the inductors of all the branch circuits are wound on the same magnetic core to be coupled with each other.

Optionally, the secondary side circuit comprises a winding; and the plurality of parallel branches are connected with the winding in series.

Optionally, the secondary side circuit comprises a plurality of windings, the plurality of windings are connected in parallel, and each winding is connected in series with one of the branches.

Optionally, the secondary side circuit comprises a plurality of windings in parallel relationship, each winding being connected in series with a plurality of the branches.

Optionally, the power device comprises: and a rectifying diode.

Optionally, the power device comprises: an N-type MOSFET or ideal diode;

the N-type MOSFET or the ideal diode is connected in series in the branch circuit through a source electrode and a drain electrode.

Optionally, the flyback circuit includes: an RCD (Residual Current Device) passive clamp circuit, or an active clamp quasi-resonant converter circuit.

The invention has the beneficial effects that:

compared with the traditional switching power supply, the parallel current-sharing flyback converter provided by the invention has the advantages that the inductors are connected in series with each power device in parallel, and the inductors connected in series with all the power devices are wound on the same magnetic core, so that the current sharing of the parallel power devices is realized through mutual coupling among the inductors, the problems of overlarge on-resistance, uneven heat dissipation and low service life of the switching power supply caused by uneven current sharing of the parallel power devices are effectively solved, and the reliability of the switching power supply is improved.

The present invention will be described in further detail with reference to the accompanying drawings.

Drawings

Fig. 1 is a schematic structural diagram of a parallel current-sharing flyback converter according to an embodiment of the present invention;

FIG. 2 shows a schematic of an ideal diode package;

fig. 3 is a schematic diagram of an exemplary proposed circuit structure of a parallel current-sharing flyback converter;

fig. 4 is a schematic diagram of an exemplary proposed circuit structure of another parallel current-sharing flyback converter;

fig. 5 is a schematic diagram of an exemplary proposed circuit structure of a parallel current-sharing flyback converter.

Detailed Description

The present invention will be described in further detail with reference to specific examples, but the embodiments of the present invention are not limited thereto.

In order to solve the problems of overlarge on-resistance, uneven heat dissipation and the like of a switching power supply caused by uneven current sharing of parallel power devices, the embodiment of the invention provides a flyback converter with parallel current sharing, which comprises: a flyback circuit and a parallel current-sharing circuit;

the parallel current-sharing circuit comprises a plurality of parallel branches, and each branch comprises a power device and an inductor L which are connected in series; each branch circuit is connected in series in a secondary side circuit of the flyback circuit, and the inductors of all the branch circuits are wound on the same magnetic core to be coupled with each other.

Referring to fig. 1, the primary winding of the transformer T and the switching tube Q form a primary circuit of the flyback circuit, a secondary winding of the transformer T and an external load R_oThe formed loop is a secondary side circuit of the flyback circuit; it can be seen that all branches are connected in series in the secondary side circuit.

Wherein, the power device can include: a rectifier diode, an N-type MOSFET, or an ideal diode. The ideal diode is not an ideal diode, but a multi-port power device, and fig. 2 schematically shows a packaging diagram of an ideal diode. Wherein VS represents a source, VD represents a drain, VDD represents a power supply pin of the device, and SENSE represents a detection port for detecting an external signal to generate a driving signal of the MOS inside the ideal diode. The inductor may be a common wound inductor or a planar inductor with a coil wound by PCB traces.

In the embodiment of the invention, the N-type MOSFET and the ideal diode are connected in series in the branch circuit through the source electrode and the drain electrode.

In addition, the flyback circuit applicable to the embodiment of the invention has various types; for example, an RCD passive clamp circuit or an active clamp level resonant converter can be used as the flyback circuit in the embodiment of the present invention.

It is understood that the flyback converter belongs to one of the switching power supplies. Compared with the traditional switching power supply, the embodiment of the invention has the advantages that the inductors are connected in series with each power device in parallel, and the inductors connected in series with all the power devices are wound on the same magnetic core, so that the current of the power devices in parallel is equalized through mutual coupling among the inductors, the problems of overlarge on-resistance, uneven heat dissipation and low service life of the switching power supply caused by uneven current sharing of the power devices in parallel are effectively solved, and the reliability of the switching power supply is improved. In addition, on the premise of ensuring the current sharing of each power device, the flyback converter provided by the embodiment of the invention can obtain better performance in the scenes of large current output and high power density.

In one embodiment, the secondary side circuit of the flyback circuit comprises a winding, and correspondingly, the parallel current sharing circuit comprises a plurality of parallel branches which are connected with the winding in series.

Referring to the flyback converter with parallel current sharing shown in fig. 3, the switching tube Q₁And a transformer T₁The primary winding forms a primary circuit of the flyback circuit; transformer T₁A loop formed by the secondary winding forms a secondary circuit of the flyback circuit; it can be seen that the inductance L₁And NMOS transistor Q₃Formed branch, and by an inductance L₂And NMOS transistor Q₂The formed branches are connected in series in the secondary side circuit; q₁、Q₂And Q₃The grid electrodes are all externally connected with a switching signal; c_oIs a filter capacitor.

In another embodiment, the secondary side circuit of the flyback circuit comprises a plurality of windings in parallel relationship, each winding being connected in series with one of the above-mentioned branches.

Here, the plurality of windings are in parallel connection, which means that they correspond to the same output voltage, that is, the output voltage of the entire flyback converter is affected by the windings in common.

It will be appreciated that where the secondary circuit comprises a plurality of windings, the non-uniform current distribution between the windings, and hence the non-uniform heat distribution between power devices connected by the different windings, will also result due to the non-uniform coupling coefficient between the different windings. Therefore, the power devices connected with the windings are connected with the inductors of the magnetic cores in series in the embodiment of the invention, so that the problem of uneven circuit distribution among different windings is solved.

Referring to the flyback converter with parallel current sharing shown in fig. 4, the switching tube Q₁And a transformer T₁The primary winding forms a primary circuit of the flyback circuit; the secondary side circuit of the flyback circuit comprises a winding A and a winding B which are connected in parallel; wherein, the inductor L₁And NMOS transistor Q₃The branch circuit is connected in series in the loop of the winding A and consists of an inductor L₂And NMOS transistor Q₂The formed branch is connected in series in a loop in which the winding B is positioned; and, these two branches also satisfy the parallel relation.

In another embodiment, the secondary side circuit of the flyback circuit comprises a plurality of windings in parallel relationship, any one of the windings may be connected in series with one or more of the above-mentioned branches.

Referring to the flyback converter with parallel current sharing shown in fig. 5, the switching tube Q₁And a transformer T₁The primary winding A forms a primary circuit of the flyback circuit; the secondary side circuit of the flyback circuit comprises two windings B and C which are connected in parallel; wherein, the inductor L₁And NMOS transistor Q₃Formed branch and formed by inductor L₂And NMOS transistor Q₃The branches are connected in series in the loop of the winding B and consist of an inductor L₃And NMOS transistor Q₄The formed branch is connected in series in a loop where the winding C is positioned; and, these three branches also satisfy the parallel relation.

Based on the flyback converters shown in fig. 3, 4, and 5, it can be seen that the embodiment of the present invention not only can implement current sharing for a plurality of power devices connected by a single winding, but also can implement current sharing for the power devices among the plurality of windings, thereby enabling current to be uniformly distributed among the power devices, enabling effective thermal management to be implemented, and improving reliability of the devices.

It should be noted that the circuit structures of the flyback converters shown in fig. 3, fig. 4, and fig. 5 are only examples, and do not limit the embodiments of the present invention, and any flyback converter that achieves current equalization by serially connecting inductors of the same magnetic core to each parallel power device belongs to the protection scope of the embodiments of the present invention.

In the description of the specification, reference to the description of the term "one embodiment", "some embodiments", "an example", "a specific example", or "some examples", etc., means that a particular feature or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples described in this specification can be combined and combined by those skilled in the art.

While the present application has been described in connection with various embodiments, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed application, from a review of the drawings, the disclosure, and the appended claims.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.