CN115378262A - A low-voltage side parallel self-current sharing dual active full-bridge converter - Google Patents

Abstract

The invention discloses a low-voltage side parallel self-current-sharing double-active full-bridge converter, each phase of sub-modules of the parallel double-active full-bridge converter consists of a switch circuit, a series inductor and an isolation transformer, the series inductors of two phase modules are connected in parallel, coupling is realized by connecting the series inductors of the phase modules in parallel, and the parameters equivalent to the series inductors of the phase modules are the same after coupling, so that the influence of the difference of the series parameters of the phase modules on the current-sharing performance of a system is eliminated, and the current sharing of the phase modules is automatically realized; the switching time sequence of the switching circuit of each phase module is the same, the working principle and the parameter design of the resonant converter cannot be influenced, and no additional circuit device is introduced into the provided scheme; the invention can be used for high-power parallel switch power supply occasions such as new energy power generation, electric automobiles, aerospace, uninterruptible power supplies, direct-current power distribution systems, energy storage systems and the like, and has the advantages of reasonable method, convenience in implementation, good universality, small size, low cost and the like.

Description

A low-voltage side parallel self-current sharing dual active full-bridge converter

technical field

The invention relates to the technical field of power electronic cascading, in particular to a low-voltage side parallel self-balanced dual-active full-bridge converter.

Background technique

In recent years, converters in power electronic systems are developing towards high power, integration, low cost, high power density and high efficiency. The resonant converter has many advantages such as electrical isolation, easy to realize soft switching control, high efficiency, etc., and can realize multiple modular solutions through parallel combination, and has developed into new energy power generation, electric vehicles, aerospace, uninterruptible power supply, DC power distribution system One of the core topologies of high-power parallel switching power supplies in other occasions.

In low-voltage and high-current applications, the parallel connection of multi-phase dual active bridge converters can effectively increase the system power capacity and reduce the stress of power tubes, so it is widely used. However, in the actual circuit, the series inductance and other parameters of each module cannot be guaranteed to be exactly the same, which will lead to the imbalance of the current of each module, which will cause serious problems such as excessive current stress of some modules. In order to solve the above problems, IEEE Transactions on Power Electronics published a paper "Dual-Active-Bridge Converter With Parallel-Connected Full Bridges in Low-Voltage Side for ZVS by Using Auxiliary Coupling Inductor" in Volume 66, Issue 9, 2019. A self-sharing topological current sharing method based on coupled inductors, but coupled inductors increase the size and cost of the system and reduce power density.

Contents of the invention

The technical problem to be solved by the present invention is aimed at the defects of the background technology. The present invention provides a low-voltage side parallel self-current sharing type dual active full-bridge converter; by paralleling the series inductors of each phase module at the same time, the The influence of module series parameter difference on system current sharing performance; this method has many advantages such as reasonable structure, convenient implementation, good versatility, high system integration, and low cost.

The present invention adopts the following technical solutions for solving the problems of the technologies described above:

A low-voltage side parallel self-current sharing type dual active full-bridge converter, including:

The first phase dual active bridge converter P ₁ , the first phase dual active bridge converter P ₁ includes a first switch circuit S11, a first series inductor L1, a first isolation transformer T1, a second switch Circuit S12 and capacitors C11 and C12 on the DC port side of the converter; the first series inductor L1 is connected in series with the primary winding _Np1 of the first isolation transformer T1; the first switch circuit S11 has an input port 1-1 and an output port 1-2, the second switch circuit S12 has an input port 1-3 and an output port 1-4;

The second phase dual active bridge converter P ₂ , the second phase dual active bridge converter P ₂ includes a first switch circuit S21, a second series inductor L2, a second isolation transformer T2, and a first The second switch circuit S22 common to the dual-phase active bridge converter and the capacitors C21 and C22 on the DC port side of the converter; the second series inductor L2 is connected in series with the primary winding _Np2 of the second isolation transformer T2; the first A switch circuit S11 has an input port 2-1 and an output port 2-2;

The first series inductor L1 and the second series inductor L2 are connected in parallel through the line l1.

Preferably, after connecting the first series inductance L1 and the second series inductance L2 of the two-phase module in parallel, the first series inductance L1 and the second series inductance L2 realize coupling, and the total series inductance value after coupling is:

The total series inductance equivalent to the series inductance values of the first phase dual active bridge converter _P1 and the second phase dual active bridge converter _P2 are Lr1 and Lr2 respectively, and Lr1=Lr2, after equivalent The expression for series inductance is:

Preferably, the switching timings of the first switching circuits S11 and S21 are the same; at the same moment, the current direction of each phase converter is the same; there is a phase shift duty between the first switching circuit Sn1 and the second switching circuit Sn2 D2, the phase shift duty cycle D2 is used to control the magnitude of the converter power and the direction of power flow.

Preferably, the first switch circuits S11 and S12 can be half-bridge circuits and full-bridge circuits; the second switch circuits S21 and S22 can be half-bridge circuits, full-bridge circuits, full-bridge rectifier circuits and multiplier circuits. Voltage rectifier circuit.

Compared with prior art, the beneficial effect of the present invention is:

1. A low-voltage side parallel self-current sharing dual active full-bridge converter provided by the present invention realizes coupling by connecting the series inductances of each phase module in parallel, and after coupling, the parameters of the series inductance equivalent to each phase module will be the same, In this way, the influence of the difference in series connection parameters of each phase module on the current sharing performance of the system is eliminated; it has many advantages such as reasonable structure, convenient implementation, good versatility, high system integration, and low cost.

2. In the low-voltage side parallel self-current equalizing dual active full-bridge converter provided by the present invention, the timing of the first switching circuit is the same, which will not affect the analysis of the working principle and inductance of the parallel dual active full-bridge converter. parameter design.

3. The present invention provides a low-voltage side parallel self-current equalizing dual active full-bridge converter. The solution provided does not introduce any additional circuit devices, does not need to add complicated control methods, and has a good current equalizing effect.

Description of drawings

In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the specific implementation or description of the prior art. Obviously, the accompanying drawings in the following description The drawings show some implementations of the present invention, and those skilled in the art can also obtain other drawings based on these drawings without creative work.

Fig. 1 is a kind of low-voltage side parallel self-current sharing type dual active full-bridge converter structure schematic diagram provided by the present invention;

Fig. 2 is a low-voltage side parallel self-current sharing type dual active full-bridge converter embodiment 1 provided by the present invention;

Figure 3 is a traditional low-voltage side parallel dual active full-bridge converter;

Fig. 4 is when the method of the present invention is not adopted, the simulation waveforms of the inductor current i _L1 and i _L2 of the low-voltage side two-phase module, and the simulation waveform of the inductor current i _L2 at the top of 47A: 67A;

Fig. 5 is the simulation waveform of the inductor current i _L1 and i _L2 of the two-phase module on the low-voltage side when the method of the present invention is adopted, and the simulation waveform of the inductor current i _L2 located at the top at 54A:53.8A.

Vp and Vs in the figure are the DC side port voltages of parallel dual active bridge converters. i _L1 and i _L2 are the inductance current of each phase module.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

A low-voltage side parallel self-current sharing type dual active full-bridge converter, including:

The first phase dual active bridge converter P ₁ , the first phase dual active bridge converter P ₁ includes a first switch circuit S11, a first series inductor L1, a first isolation transformer T1, a second switch Circuit S12 and capacitors C11 and C12 on the DC port side of the converter; the first series inductor L1 is connected in series with the primary winding _Np1 of the first isolation transformer T1; the first switch circuit S11 has an input port 1-1 and an output port 1-2, the second switch circuit S12 has an input port 1-3 and an output port 1-4;

The second phase dual active bridge converter P ₂ , the second phase dual active bridge converter P ₂ includes a first switch circuit S21, a second series inductor L2, a second isolation transformer T2, and a first The second switch circuit S22 common to the dual-phase active bridge converter and the capacitors C21 and C22 on the DC port side of the converter; the second series inductor L2 is connected in series with the primary winding _Np2 of the second isolation transformer T2; the first A switch circuit S11 has an input port 2-1 and an output port 2-2;

The first series inductor L1 and the second series inductor L2 are connected in parallel through the line l1.

As a specific implementation, after connecting the first series inductance L1 and the second series inductance L2 of the two-phase module in parallel, the first series inductance L1 and the second series inductance L2 realize coupling, and the total series inductance after coupling Values are:

The total series inductance equivalent to the series inductance values of the first phase dual active bridge converter _P1 and the second phase dual active bridge converter _P2 are Lr1 and Lr2 respectively, and Lr1=Lr2, after equivalent The expression for series inductance is:

As a specific implementation manner, the switching sequence of the first switching circuits S11 and S21 is the same; at the same time, the current direction of each phase converter is the same; between the first switching circuit Sn1 and the second switching circuit Sn2 There is a phase-shift duty cycle D2, which is used to control the power magnitude and power flow direction of the converter.

As a specific implementation, the first switch circuits S11, S12 can be half-bridge circuits, full-bridge circuits; the second switch circuits S21, S22 can be half-bridge circuits, full-bridge circuits, full-bridge circuits, etc. Bridge rectifier circuit and voltage doubler rectifier circuit.

As can be seen from accompanying drawing 4 and accompanying drawing 5, without adopting the present invention, the inductive current i ₁₁ and i ₂₁ inductive current simulation waveforms of the traditional (accompanying drawing 3) parallel dual active full-bridge converter on the low voltage side are very different, very The unbalanced current sharing error reached 14.2%. However, after adopting the method proposed in this patent, the simulated waveforms of the inductor currents i ₁₁ and i ₂₁ of the parallel dual active full-bridge converter on the low-voltage side have little difference and are very balanced, and the current-sharing error is less than 1%.

The simulation parameters are: Vp=110V, Vs=125V, L1=2.0μH, L2=1.5μH, transmission power 8kW, switching frequency 50kHz.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (4)

1. The utility model provides a low pressure side is parallelly connected from current-sharing type double-active full-bridge converter which characterized in that includes:

phase 1 dual active bridge converter P ₁ Said 1 st phase dual active bridge converter P ₁ The direct-current converter comprises a first switching circuit S11, a 1 st series inductor L1, a 1 st isolation type transformer T1, a second switching circuit S12 and capacitors C11 and C12 on the direct-current port side of the converter; the 1 st series inductor L1 and the 1 st isolation transformer T1 primary winding N _p1 Are connected in series; the first switching circuit S11 has an input port 1-1 and an output port 1-2, and the second switching circuit S12 has an input port 1-3 andoutput ports 1-4;

phase 2 dual active bridge converter P ₂ Said 2 nd phase dual active bridge converter P ₂ The inverter comprises a first switching circuit S21, a 2 nd series inductor L2, a 2 nd isolation type transformer T2, a second switching circuit S22 shared with a first-phase double-active-bridge inverter, and capacitors C21 and C22 at the direct-current port side of the inverter; the 2 nd series inductor L2 and the primary winding N of the 2 nd isolation transformer T2 _p2 Are connected in series; the first switching circuit S11 has an input port 2-1 and an output port 2-2;

the first series inductor L1 and the second series inductor L2 are connected in parallel through a line L1.

2. The low-voltage side parallel self-current-sharing dual-active full-bridge converter according to claim 1, wherein after the 1 st series inductor L1 and the 2 nd series inductor L2 of the two-phase module are connected in parallel, the 1 st series inductor L1 and the 2 nd series inductor L2 are coupled, and the total series inductance value after coupling is:

total series inductance equivalent to first-phase dual-active bridge converter P ₁ And a second phase dual active bridge converter P ₂ And Lr1= Lr2, the equivalent series inductance expression is:

3. the low-voltage side parallel self-current-sharing double-active full-bridge converter according to claim 1, wherein: the switching time sequences of the first switching circuits S11 and S21 are the same; at the same time, the current direction of each phase transformer is the same; a phase-shifting duty ratio D2 exists between the first switch circuit Sn1 and the second switch circuit Sn2, and the phase-shifting duty ratio D2 is used for controlling the power magnitude and the power flow direction of the converter.

4. The low-voltage side parallel self-current-sharing double-active full-bridge converter according to claim 2, wherein: the first switch circuits S11 and S12 can be half-bridge circuits or full-bridge circuits; the second switch circuits S21 and S22 can be a half-bridge circuit, a full-bridge rectifier circuit, and a voltage-doubler rectifier circuit.

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