阅读说明：本技术 隔离型升压双向dc-dc变换器拓扑结构 (Isolated boost bidirectional DC-DC converter topological structure ) 是由 郑泽东 刘基业 李驰 王哲 于 2020-04-02 设计创作，主要内容包括：本发明公开了一种隔离型升压双向DC-DC变换器拓扑结构,包括：前级Boost电路、集成变压器和后级H桥电路,其中,前级Boost电路包括第一两相交错并联的Boost变换器,集成变压器为耦合电感结构包括Boost电感部分和理想变压器结构,第一两相交错并联的Boost变换器与集成变压器的Boost电感部分串联,集成变压器的理想变压器结构与后级H桥电路串联。该拓扑结构选用器件少,电路简单且集成度高,能够较好地解决输入电流不连续的问题,并极大地抑制输入电流纹波和输出电压纹波,使其对电流纹波要求更高的锂电池应用场景。(The invention discloses an isolated boost bidirectional DC-DC converter topological structure, which comprises: the integrated transformer comprises a first front-stage Boost circuit, an integrated transformer and a rear-stage H-bridge circuit, wherein the first front-stage Boost circuit comprises a first two-phase interleaved parallel Boost converter, the integrated transformer is a coupled inductor structure and comprises a Boost inductor part and an ideal transformer structure, the first two-phase interleaved parallel Boost converter is connected with the Boost inductor part of the integrated transformer in series, and the ideal transformer structure of the integrated transformer is connected with the rear-stage H-bridge circuit in series. The topological structure has few selected devices, simple circuit and high integration level, can better solve the problem of discontinuous input current, greatly inhibits input current ripple and output voltage ripple, and enables the topological structure to have a lithium battery application scene with higher requirements on the current ripple.)

1. An isolated boost bidirectional DC-DC converter topology, comprising: a front-stage Boost circuit, an integrated transformer and a rear-stage H-bridge circuit, wherein,

the front-stage Boost circuit comprises a first two-phase interleaved parallel Boost converter, the integrated transformer is a coupling inductance structure and comprises a Boost inductance part and an ideal transformer structure, the first two-phase interleaved parallel Boost converter is connected with the Boost inductance part of the integrated transformer in series, and the ideal transformer structure of the integrated transformer is connected with the rear-stage H-bridge circuit in series.

2. The isolated Boost bidirectional DC-DC converter topology structure of claim 1, wherein two switching tubes are arranged on each bridge arm of the first two-phase interleaved Boost converter.

3. The isolated Boost bidirectional DC-DC converter topology structure of claim 2, wherein when two switches on a bridge arm are simultaneously turned on, the first two-phase interleaved parallel Boost converters charge the Boost inductance part, and when the first two-phase interleaved parallel Boost converters are in any remaining combined switch state, the Boost inductance part discharges a rear-stage H-bridge circuit.

4. The isolated Boost bidirectional DC-DC converter topology structure of claim 1, wherein the pre-stage Boost circuit further comprises a first power supply and a first clamping capacitor, and the first power supply and the first clamping capacitor are respectively connected in parallel with the first two Boost converters which are staggered and connected in parallel.

5. The isolated boost bidirectional DC-DC converter topology of claim 4, in which the voltage of the first clamping capacitor is represented as:

wherein the content of the first and second substances,representing the voltage of the first clamping capacitor, U₁And D represents the duty ratio of the previous-stage Boost circuit.

6. The isolated Boost bidirectional DC-DC converter topology of claim 1, wherein a phase angle of a phase difference between a voltage of the front stage Boost circuit and a voltage of the rear stage H-bridge circuit is related to a flow direction of energy.

7. The isolated Boost bidirectional DC-DC converter topology of claim 1, wherein the back-stage H-bridge circuit comprises a second two-phase interleaved parallel Boost converter, a second clamping capacitor, a second power supply, a leakage inductance, and a secondary side of an ideal transformer portion, wherein the second two-phase interleaved parallel Boost converter is connected in parallel with the second clamping capacitor, the second two-phase interleaved parallel Boost converter is connected in series with the leakage inductance, the leakage inductance is connected in series with the secondary side of the ideal transformer portion, and the second clamping capacitor is connected in parallel with the second power supply.

Technical Field

The invention relates to the technical field of power electronics and electric energy conversion in the electrical technology, in particular to a novel topology of an isolated boost bidirectional DC-DC converter.

Background

With the increase of energy crisis and global warming, renewable energy sources such as lithium batteries, solar energy, wind energy and the like are more and more concerned by people. Compared with the traditional battery, the lithium battery has the advantages of long endurance, repeated and repeated utilization, cleanness, no pollution, high energy density and the like. The isolated boost bidirectional DC-DC converter has the advantages of bidirectional flow of energy, high boost ratio, adjustable transformation ratio and the like, and is widely applied to the field of renewable energy sources such as lithium batteries and the like.

The isolated Boost bidirectional DC-DC converter is generally realized by adopting a Boost converter and a DAB circuit, and the circuit has more devices and poorer integration. In a traditional isolated boost bidirectional DC-DC converter, an input side inductor has a large size and cannot be integrated into a transformer, which results in a large circuit. For a single-phase coupling inductance type Boost converter, the input current is discontinuous when the single-phase coupling inductance type Boost converter works normally, and the single-phase coupling inductance type Boost converter is not suitable for a lithium battery application scene with high requirements on current ripples. In addition, the traditional isolated Boost bidirectional DC-DC converter realizes a high Boost ratio by adopting cascade connection of a Boost converter and a DAB circuit, and has more circuit elements and complex circuit.

Disclosure of Invention

The present invention is directed to solving, at least to some extent, one of the technical problems in the related art.

Therefore, the invention aims to provide an isolated boost bidirectional DC-DC converter topology structure.

In order to achieve the above object, an embodiment of the present invention provides an isolated boost bidirectional DC-DC converter topology, including: the method comprises the following steps: the integrated transformer comprises a front-stage Boost circuit, an integrated transformer and a rear-stage H-bridge circuit, wherein the front-stage Boost circuit comprises a first two-phase interleaved parallel Boost converter, the integrated transformer is a coupling inductance structure and comprises a Boost inductance part and an ideal transformer structure, the first two-phase interleaved parallel Boost converter is connected with the Boost inductance part of the integrated transformer in series, and the ideal transformer structure of the integrated transformer is connected with the rear-stage H-bridge circuit in series.

The isolated Boost bidirectional DC-DC converter topological structure overcomes the defects that the traditional isolated bidirectional Boost converter cannot realize integration and solve the problem of discontinuous input current, and is suitable for the application scene of lithium batteries with high requirements on current ripples.

In addition, the topology structure of the isolated boost bidirectional DC-DC converter according to the above embodiment of the present invention may further have the following additional technical features:

further, in an embodiment of the present invention, two switching tubes are disposed on each bridge arm of the first two interleaved Boost converters in parallel.

Further, in an embodiment of the present invention, when two switches on a bridge arm are simultaneously turned on, the first two-phase interleaved Boost converters in parallel charge the Boost inductor part, and when the first two-phase interleaved Boost converters are in any remaining combined switch state, the Boost inductor part discharges a rear-stage H-bridge circuit.

Further, in an embodiment of the present invention, the preceding stage Boost circuit further includes a first power supply and a first clamping capacitor, and the first power supply and the first clamping capacitor are respectively connected in parallel with the first two interleaved Boost converters in parallel.

Further, in one embodiment of the present invention, the voltage of the first clamping capacitor may be expressed as:

wherein the content of the first and second substances,representing the voltage of the first clamping capacitor, U₁And D represents the duty ratio of the previous-stage Boost circuit.

Further, in one embodiment of the present invention, a phase angle of a phase difference between the voltage of the front stage Boost circuit and the voltage of the rear stage H-bridge circuit is related to a flow direction of energy.

Further, in an embodiment of the present invention, the post-stage H-bridge circuit includes a second two-phase interleaved parallel Boost converter, a second clamping capacitor, a second power supply, a leakage inductance, and a secondary side of the ideal transformer portion, where the second two-phase interleaved parallel Boost converter is connected in parallel with the second clamping capacitor, the second two-phase interleaved parallel Boost converter is connected in series with the leakage inductance, the leakage inductance is connected in series with the secondary side of the ideal transformer portion, and the second clamping capacitor is connected in parallel with the second power supply.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The foregoing and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic structural diagram of an isolated boost bidirectional DC-DC converter topology according to an embodiment of the present invention;

FIG. 2 is an equivalent circuit diagram of an isolated boost bidirectional DC-DC converter topology according to one embodiment of the present invention;

fig. 3 is a waveform diagram illustrating operation of a CMM mode circuit according to an embodiment of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

An isolated boost bidirectional DC-DC converter topology proposed according to an embodiment of the present invention is described below with reference to the accompanying drawings.

Fig. 1 is a schematic structural diagram of an isolated boost bidirectional DC-DC converter topology according to an embodiment of the present invention.

As shown in fig. 1, the isolated boost bidirectional DC-DC converter topology includes: a front-stage Boost circuit 100, an integrated transformer 200 and a rear-stage H-bridge circuit 300.

The front-stage Boost circuit comprises a first two-phase interleaved parallel Boost converter, the integrated transformer is a coupling inductance structure and comprises a Boost inductance part and an ideal transformer structure, the first two-phase interleaved parallel Boost converter is connected with the Boost inductance part of the integrated transformer in series, and the ideal transformer structure of the integrated transformer is connected with the rear-stage H-bridge circuit in series.

Further, in an embodiment of the present invention, two switching tubes are disposed on each bridge arm of the first two interleaved Boost converters in parallel.

Further, in an embodiment of the present invention, when two switches on a bridge arm are simultaneously turned on, the first two-phase interleaved parallel Boost converter charges the Boost inductor part, and when the first two-phase interleaved parallel Boost converter is in a state of any remaining combination switch, the Boost inductor part discharges the rear-stage H-bridge circuit.

Specifically, as shown in the left side of fig. 1, there are two Boost converters connected in parallel, each bridge arm is equivalent to one Boost converter, when two switching tubes on the bridge arm are simultaneously turned on, the Boost inductor part is charged, and when other switching states are performed, the Boost inductor part discharges to the rear-stage H-bridge circuit, thereby realizing higher voltage gain.

Furthermore, the front-stage Boost circuit further comprises a first power supply and a first clamping capacitor, and the first power supply and the first clamping capacitor are respectively connected in parallel with the first two staggered Boost converters in parallel.

Wherein, in the Boost converter, a first clamping capacitor C_SEquivalent to the load, the first clamp capacitor voltage can be expressed as:

wherein the content of the first and second substances,representing the voltage of the first clamping capacitor, U₁And D represents the duty ratio of the previous-stage Boost circuit.

The voltage at two sides of the secondary side leakage inductance can be obtained according to the voltage of the first clamping capacitor:

U_cd＝U₂

therefore, the equivalent circuit of the converter can be represented as fig. 2, the working principle of the converter is similar to that of a DAB converter, and the control method is PWM control plus phase shift control, namely, the duty ratio of the front-stage Boost circuit and the rear-stage H-bridge circuit and the phase shift angle between the two circuits are controlled.

That is, the phase angle of the phase difference between the voltage of the preceding stage Boost circuit and the voltage of the succeeding stage H-bridge circuit is related to the flow direction of energy, and the voltage u is changed_abAnd voltage u_cdThe phase angle between them changes the direction of the energy flow.

Further, as shown in fig. 1, the integrated transformer in the embodiment of the present invention may be divided into a Boost inductor part and an ideal transformer part, wherein the Boost inductor part includes an inductor L_m1And an inductor L_m2The ideal transformer part comprises a primary side and a secondary side, an inductor L_m1And an inductor L_m2Connected in parallel with the two primary sides of an ideal transformer, respectively, inductor L_m1And an inductor L_m2Has the same function as a common boost inductor, except that the inductor L_m1And L_m2The integrated inductor is not a separate inductor but an inductor integrated in the transformer, the integrated inductor has no electromagnetic coupling relation with a secondary side, and the integrated inductor is in electromagnetic coupling relation with the secondary side after being connected with a primary side in parallel.

Further, in an embodiment of the present invention, the post-stage H-bridge circuit includes a second two-phase interleaved parallel Boost converter, a second clamping capacitor, a second power supply, a leakage inductance, and an ideal transformer portion, wherein the second two-phase interleaved parallel Boost converter is connected in parallel with the second clamping capacitor, the second two-phase interleaved parallel Boost converter is connected in series with the leakage inductance, the leakage inductance is connected in series with a secondary side of the ideal transformer portion, and the second clamping capacitor is connected in parallel with the second power supply.

The operation principle of the isolated boost bidirectional DC-DC converter topology according to the embodiment of the present invention is described below with reference to fig. 3.

The topological structure of the embodiment of the invention is supposed to work in a CCM mode, the duty ratio D of the left-side Boost converter is less than 0.5, the duty ratio of the right-side H bridge is 0.5, and the phase shift angle between the left-side Boost converter and the right-side H bridge is equal to that between the left-side Boost converter and the right-side H bridge.

From the previous analysis u can be obtained_abAnd u_cdThe amplitude of (d) is:

U_cd＝U₂

the primary side current can be further deduced according to the obtained leakage inductance current.

The primary current consisting of two parts, exciting inductor current i_m1、i_m2And coupling of inductor current Ni_Ls、-Ni_LsThat is to say have

i₁＝i_m1+Ni_Ls

i₂＝i_m2-Ni_Ls

The input current being the sum of the currents flowing through the exciting inductances in the two branches

i_in＝i₁+i₂＝i_m1+i_m2

As shown in fig. 3, the excitation current i_m1And i_m2Is determined by the voltage applied across the exciting inductor. The two are added to obtain the input current waveform. So that the frequency of the input current waveform is 2 times of the switching frequency, and the rising slope is the exciting current i_m1And i_m2Difference in slope, falling slope being excitation current i_m1And i_m2The sum of the slopes.

At [ t ]₀,t₂]Time of input current i_inTo be provided withThe slope rises;

at [ t ]₂,t₃]Time of input current i_inTo be provided withThe slope is reduced;

therefore, the ripple value Δ i of the input current_inIs composed of

[0,t₁]In the time period, in the Boost converter, the control signal of the switch tube S1 is in a high level, the control signal of the switch tube S4 is in a high level, and in the following H bridge, the control signals of the switch tubes S6 and S7 are in a high level, so that the control signals of the switch tubes S6 and S7 are in a high level, and therefore

u_ab＝-U_ab

u_cb＝U_cd

u_Ls＝u_ab-u_cd＝-(U_ab+U_cd)

Thereby leaking the inductive current i_LsWith a slope (U)_ab+U_cd) And (4) descending.

[t₁,t₂]In the time period, in the Boost converter, the control signal of the switch tube S1 is in a high level, the control signal of the switch tube S4 is in a high level, and in the following H bridge, the control signals of the switch tubes S5 and S8 are in a high level, so that the control signals of the switch tubes S5 and S8 are in a high level, and therefore

u_ab＝-U_ab

u_cb＝-U_cd

u_Ls＝u_ab-u_cd＝-(U_ab-U_cd)

Thereby leaking the inductive current i_LsWith a slope (U)_ab-U_cd) And (4) descending.

[t₂,t₃]In the time period, in the Boost converter, the control signal of the switch tube S2 is in a high level, the control signal of the switch tube S3 is in a high level, and in the following H bridge, the control signals of the switch tubes S5 and S8 are in a high level, so that the control signals of the switch tubes S5 and S8 are in a high level, and therefore

u_ab＝0

u_cb＝-U_cd

u_Ls＝u_ab-u_cd＝U_cd

Thereby leaking the inductive current i_LsWith a slope U_cdAnd (4) rising.

[t₃,t₄]In the time period, in the Boost converter, the control signal of the switch tube S1 is in a high level, the control signal of the switch tube S4 is in a high level, and in the following H bridge, the control signals of the switch tubes S5 and S8 are in a high level, so that the control signals of the switch tubes S5 and S8 are in a high level, and therefore

u_ab＝U_ab

u_cb＝-U_cd

u_Ls＝u_ab-u_cd＝U_ab+U_cd

Thereby leaking the inductive current i_LsWith a slope (U)_ab+U_cd) And (4) rising.

[t₄,t₅]In the time period, in the Boost converter, the control signal of the switch tube S2 is in a high level, the control signal of the switch tube S3 is in a high level, and in the following H bridge, the control signals of the switch tubes S6 and S7 are in a high level, so that the control signals of the switch tubes S6 and S7 are in a high level, and therefore

u_ab＝U_ab

u_cb＝U_cd

u_Ls＝u_ab-u_cd＝U_ab-U_cd

Thereby leaking the inductive current i_LsWith a slope (U)_ab-U_cd) And (4) rising.

[t₅,t₆]In the time period, in the Boost converter, the control signal of the switch tube S2 is in a high level, the control signal of the switch tube S4 is in a high level, and in the following H bridge, the control signals of the switch tubes S6 and S7 are in a high level, so that the control signals of the switch tubes S6 and S7 are in a high level, and therefore

u_ab＝0

u_cb＝U_cd

u_Ls＝u_ab-u_cd＝-U_cd

Thereby leaking the inductive current i_LsWith a slope U_cdAnd (4) descending.

[t₆,t₇]The time period starts a new cycle again, and the working principle is the same as before.

In summary, according to the isolated Boost bidirectional DC-DC converter topology structure provided by the embodiment of the present invention, by adding the coupling inductor structure, the Boost converter can flexibly improve the voltage gain, and the gain range of the Boost converter is greatly expanded; the front stage is formed by two-phase interleaved Boost converters which are connected in parallel and are connected with the Boost inductor part of the coupling inductor in series, so that the problem of discontinuous input current can be better solved, and input current ripples and output voltage ripples are greatly inhibited; the inductor in the H bridge is integrated into the transformer, so that the circuit integration level is high; in addition, the embodiment of the invention can realize the bidirectional flow of energy, further realize the double-quadrant operation, realize the functions of two single-phase DC-DC converters and is suitable for the application occasions of lithium batteries and the like which need frequent charging and discharging.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, 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, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.