CN111669060A

CN111669060A - Method for solving primary multipath parallel current sharing by utilizing magnetic circuit full coupling

Info

Publication number: CN111669060A
Application number: CN202010666316.XA
Authority: CN
Inventors: 徐艳超; 陈超飞; 李金洁; 吴飞飞; 赵耀峰; 张现民; 李维旭; 杨旭东
Original assignee: Shijiazhuang Tonghe Electronics Co Ltd
Current assignee: Shijiazhuang Tonghe Electronics Co Ltd
Priority date: 2020-07-10
Filing date: 2020-07-10
Publication date: 2020-09-15

Abstract

The invention provides a method for solving the problem of primary multi-path parallel current sharing by utilizing the full coupling of a magnetic circuit, which can realize the autonomous current sharing of multi-path direct parallel connection, and the multi-path can use one set of driving circuit, thereby greatly simplifying the circuit topology, optimizing the design method of an inductor and a transformer, and not increasing any other hardware cost. The method is realized by designing a direct parallel multi-path inductor and a transformer into a full magnetic coupling mode, adopting a parallel wire same-direction winding method when winding multi-path windings, and forcibly dividing abnormal current caused by inconsistent parameters such as switching devices, capacitors, loop parasitics and the like by utilizing the principle that equal coils of the windings are in phase and the windings are mutually embedded with the transformer.

Description

Method for solving primary multipath parallel current sharing by utilizing magnetic circuit full coupling

Technical Field

The invention relates to a method for solving primary multipath parallel current sharing by utilizing magnetic circuit full coupling.

Technical Field

In the switching power supply, when a plurality of primary side branches are directly connected in parallel, static and dynamic non-uniform current can be caused by parameters such as internal threshold voltage and conduction internal resistance of the switching tube and external parameters such as loop stray inductance, parasitic capacitance and device dispersion.

With the improvement of the power grade and the density of the switching power supply, in order to solve the problem of insufficient capacity of the original device, a multi-path parallel connection mode is mostly adopted. And multiple branches are directly connected in parallel, and dynamic and static non-uniform currents are inevitably brought by self discrete parameters of a switch device, a capacitor and the like and loop parasitic parameters of layout wiring, a driving circuit and the like. And the methods of device screening, loop independence and the like are adopted, so that the cost is greatly increased.

Disclosure of Invention

In order to solve the problems, when multiple paths are connected in parallel, a primary side inductor and a transformer are designed to be in a full magnetic coupling mode, and primary non-uniform current caused by the problem is solved by clamping the end voltage of the inductor and the end voltage of the transformer by using a principle similar to that of the transformer.

The technical scheme provided by the embodiment of the application is as follows:

when two parallel inductors are wound, two windings are wound on the same magnetic core in parallel and in the same direction, and the primary winding of the transformer is wound in the same way. Two paths of inductors and the primary of the transformer are highly coupled, two windings are induced in the same magnetic field, electromotive force is induced on one path of the other path when any path is excited, voltages at two ends of the inductors are clamped by a certain phase, the voltages of the certain phase are finally transformed, and the voltages are the same at each moment. In addition, because the winding adopts double wires and is wound on the same magnetic core in parallel, the inductance parameters expressed by the winding are highly consistent. According to the formula UL ═ Ldi (t)/dt, two paths i can be known_LThe same is true. The two half-bridge LLC topologies are directly connected in parallel, a first parallel branch is connected in parallel by switching tubes V1 and V3 and then sequentially connected in series with a resonant capacitor C1, a resonant inductor L1, a main transformer T1, rectifier diodes D1, D2, D3 and D4, and then connected in parallel with an output filter capacitor CD 1; second parallel branchAfter the switching tubes V2 and V4 are connected in parallel, the resonant capacitor C2, the resonant inductor L2, the main transformer T2, the rectifier diodes D5, D6, D7 and D8 are sequentially connected in series, and the filter capacitor CD3 is connected in parallel. The two half-bridges are driven identically, i.e. V1, V2 use the same DRIVE signal DRIVE1_ a and V3, V4 use the same DRIVE signal DRIVE1_ B. The branch 1 and the branch 2 work in the same state, primary current can simultaneously flow through L1 and L2, T1 and T2 in the same direction, parameters of L1 and L2, and parameters of T1 and T2 designed by the method are consistent and highly coupled, and induced electromotive force generated by the method is equivalent to the same direction. When the loop impedances of I1 and I2 are equal, the two branches I1 and I2 have the same size and direction, the inductance is the same as the induced voltage generated by the primary side of the transformer, and the two branches with the same terminal voltage do not block each other; when the impedances of loops where I1 and I2 are located are unequal, two paths of current tend to generate deviation, so that induced voltages generated at the primary side of an inductor and a transformer are different, the deviation of the generated induced voltages just resists to external voltages causing current deviation, the terminal voltages of the inductor and the transformer are the same finally, voltage deviation is compensated by a resonant capacitor, a switching device and the like, and the same terminal voltages act on L1 and L2, T1 and T2 with the same parameter height to bring the same I1 and I2, so that current equalization of a branch 1 and a branch 2 is realized.

The circuit can be further expanded to realize the parallel connection of more branches, and the method is characterized in that multiple paths of inductance windings are wound on the same magnetic core in parallel and in the same direction, and multiple paths of primary windings of the transformer are wound on the same magnetic core in parallel and in the same direction. The principle is that the two paths are connected in parallel.

By using the method, the independent current sharing of multiple paths of direct parallel connection can be realized, and one set of driving circuit can be used for the multiple paths, so that the circuit topology is greatly simplified, the design method of the inductor and the transformer is optimized, and the cost of other hardware is not increased. The method is realized by designing a direct parallel multi-path inductor and a transformer into a full magnetic coupling mode, adopting a parallel wire same-direction winding method when winding multi-path windings, and forcibly dividing abnormal current caused by inconsistent parameters such as switching devices, capacitors, loop parasitics and the like by utilizing the principle that equal coils of the windings are in phase and the windings are mutually embedded with the transformer.

Drawings

FIG. 1 is a two-way LLC parallel embodiment of the invention;

FIG. 2 is a circuit for performing simulation comparison of two parallel LLC topologies;

FIG. 3 is a 'independent inductor and transformer' simulation waveform;

FIG. 4 is a simulation waveform of a fully coupled inductor and transformer;

fig. 5 shows the circuit principle when three branches are connected in parallel.

Detailed Description

The technical solution of the present invention is described in detail below with reference to the accompanying drawings and the detailed description.

Take two LLC in parallel as an example. When two parallel inductors are wound, two windings are wound on the same magnetic core in parallel and in the same direction, and the primary winding of the transformer is wound in the same way. Two paths of inductors and the primary of the transformer are highly coupled, two windings are induced in the same magnetic field, electromotive force is induced on one path of the other path when any path is excited, voltages at two ends of the inductors are clamped by a certain phase, the voltages of the certain phase are finally transformed, and the voltages are the same at each moment. In addition, because the winding adopts double wires and is wound on the same magnetic core in parallel, the inductance parameters expressed by the winding are highly consistent. From the formula UL ═ ldi (t)/dt, it can be seen that the two ils are identical. The circuit is shown in figure 1:

fig. 1 shows that two half-bridge LLC topologies are directly connected in parallel, the first parallel branch is composed of switching tubes V1, V3, a resonant capacitor C1, a resonant inductor L1, a main transformer T1, rectifier diodes D1, D2, D3, D4, and an output filter capacitor CD 1; the second parallel branch is composed of switching tubes V2 and V4, a resonant capacitor C2, a resonant inductor L2, a main transformer T2, rectifier diodes D5, D6, D7 and D8 and an output filter capacitor CD 3. The two half-bridges are driven identically, namely V1 and V2 use the same DRIVE signal DRIVE1_ A, V3 and V4 use the same DRIVE signal DRIVE1_ B, branch 1 and branch 2 work in the same state, primary current can flow through L1 and L2 and T1 and T2 simultaneously and in the same direction, L1 and L2 and T1 and T2 designed by the method are consistent in parameters and highly coupled, and induced electromotive force generated by the half-bridges is equivalent to the same direction. When the loop impedances of I1 and I2 are equal, the two branches I1 and I2 have the same size and direction, the inductance is the same as the induced voltage generated by the primary side of the transformer, and the two branches with the same terminal voltage do not block each other; when the impedances of loops where I1 and I2 are located are unequal, two paths of current tend to generate deviation, so that induced voltages generated at the primary side of an inductor and a transformer are different, the deviation of the generated induced voltages just resists to external voltages causing current deviation, the terminal voltages of the inductor and the transformer are the same finally, voltage deviation is compensated by a resonant capacitor, a switching device and the like, and the same terminal voltages act on L1 and L2, T1 and T2 with the same parameter height to bring the same I1 and I2, so that current equalization of a branch 1 and a branch 2 is realized. For two-way parallel LLC topology using the method and without the method, the simulation comparison circuit is as shown in fig. 2:

in fig. 2, the device discreteness can be reflected most directly by changing the resonant capacitance parameter, the parameter C2 parameter is changed to be positive deviation 20nF according to the deviation of changing the capacitance capacity of C1 and C2 by 10%, the C1 is set to be 200nF, the C2 is set to be 220nF, and other parameters are kept unchanged. Compared with simulation 'independent inductor and transformer' and 'full coupling inductor and transformer', the specific simulation waveforms are shown in fig. 3 and 4 in detail.

Fig. 3 is a simulation waveform of 'independent inductor and transformer', and fig. 4 is a simulation waveform of 'fully coupled inductor and transformer'. In the figure, IP1 and IP2 represent two primary currents, VL1 and VL2 represent two inductor terminal voltages, and VT1 and VT2 represent two transformer primary side end voltages. According to simulation results, after device deviation is introduced into the parallel circuit, a circuit with measures is not adopted, the voltage deviation between the two branch inductors and the terminal voltage of the transformer is large, and primary current poles are not uniform; the circuit using the method has the advantages that the two branch inductors are completely consistent with the terminal voltage of the transformer, and the primary current is relatively uniform and consistent.

The circuit can be further expanded to realize the parallel connection of more branches, and the method is characterized in that multiple paths of inductance windings are wound on the same magnetic core in parallel and in the same direction, and multiple paths of primary windings of the transformer are wound on the same magnetic core in parallel and in the same direction. The principle is that the two paths are connected in parallel. The specific circuit is shown in fig. 5 in detail, and fig. 5 shows a circuit principle when three branches are connected in parallel, so that parallel current sharing of more branches can be realized.

Claims

1. A method for solving primary multipath parallel current sharing by utilizing magnetic circuit full coupling is characterized in that: when two parallel inductors are wound, two windings are wound on the same magnetic core in parallel and in the same direction, and the primary winding of the transformer is wound in the same way. Two paths of inductors and the primary level of the transformer are highly coupled, two windings are induced under the same magnetic field, electromotive force is induced on one path of the other path when any path is excited, the voltage at two ends of each inductor is clamped by a certain phase, the voltage of the certain phase is finally expressed, and the voltage is the same at each moment; in addition, because the winding adopts double wires and is wound on the same magnetic core in parallel, the inductance parameters expressed by the winding are highly consistent; according to the formula UL ═ Ldi (t)/dt, two paths i can be known_LThe same is true.

2. The implementation circuit of the method of claim 1, wherein: the device comprises two half-bridge LLC topologies which are directly connected in parallel, wherein a first parallel branch is connected in parallel by switching tubes V1 and V3 and then sequentially connected in series with a resonant capacitor C1, a resonant inductor L1, a main transformer T1, rectifier diodes D1, D2, D3 and D4, and then connected in parallel with an output filter capacitor CD 1; after the second parallel branch is connected in parallel by the switching tubes V2 and V4, the second parallel branch is sequentially connected in series with a resonant capacitor C2, a resonant inductor L2, a main transformer T2, rectifier diodes D5, D6, D7 and D8 and a filter capacitor CD3 in parallel; the two half-bridges are driven identically, the DRIVE signal DRIVE1_ A is connected with V1 and V2, and the DRIVE signal DRIVE1_ B is connected with V3 and V4.

3. The method according to claim 1 or 2, characterized in that: the multi-path inductance windings are all wound on the same magnetic core in parallel and in the same direction, and the multi-path transformer primary windings are all wound on the same magnetic core in parallel and in the same direction, and are connected in parallel with two paths according to the principle.