Three-phase bidirectional AC-DC converter circuit

Abstract

The present application discloses a three-phase bidirectional AC-DC converter circuit comprising three boosting circuits having the same structure and an output capacitor circuit, each of the boosting circuits comprising an inductor circuit and a switching circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, the switching circuit comprising eight switching tubes and four diodes, each of the four switching tubes being connected in series to form bridge arms, two bridge arms being connected in parallel to one side of the output capacitor circuit, each of the two diodes being connected in series and in parallel to the two switching tubes located in the middle of a bridge arm, and a connection point between the two series-connected diodes being connected to the output capacitor circuit.wherein the like end of the primary winding of the self-coupling inductor and the unlike end of the secondary winding are connected to one end of the first inductor, and while the like end of the primary winding of the self-coupling inductor and the like end of the secondary winding are each connected to the midpoint of a bridge arm.

Description

[0001] This application is based on and claims priority from Chinese Patent Application No. 202211104497.2 filed on September 9, 2022, the entire contents of which are hereby incorporated into this application as a whole. TECHNICAL FIELD

[0002] The present application relates to the technical field of power conversion, in particular to a three-phase bidirectional AC-DC converter circuit. STATE OF THE ART

[0003] Bidirectional AC-DC converter circuits are circuits for the mutual conversion of commercial AC and DC power, making the power conversion system simpler and more efficient. With the rapid development of the renewable energy industry, bidirectional AC-DC converter circuits are widely used in many renewable energy electronic devices such as photovoltaic energy storage and APF. Especially in recent years, photovoltaics, wind energy, combined charging and storage systems, and energy storage have developed toward higher power, increasing the demand for high-performance three-phase AC-DC converter circuits and making their application more and more widespread.However, the industry currently still uses traditional three-level T-type or I-type technologies to implement bidirectional AC-to-DC converter circuits. Due to industry practices and the limitations of high-voltage semiconductors, the switching frequency currently rarely exceeds 20 kHz. This poses many challenges for both power inductance and EMC filtering, including large size, high cost, and difficulty in filtering.Especially in the filtering to a standard sine wave through a three-level inverter to achieve low-cost filtering, the industry generally uses LCL filter, the second resonance of the LCL filter is very easy to cause the control loop oscillation, especially in the parallel connection of multiple machines, the second resonance of the LCL filter to the impact of the obvious, the oscillation is more likely to occur, bringing more challenges to the loop control. CONTENT OF THIS APPLICATION

[0004] The technical problem to be solved by the present application is to provide a three-phase bidirectional AC-DC converter circuit that can increase the switching frequency and achieve low-cost filtering while reducing the input and output voltage and current ripple and reducing the difficulty of control.

[0005] To solve the technical problem, the present application provides a three-phase bidirectional AC-DC converter circuit comprising three amplifying circuits having the same structure and an output capacitor circuit, each of the amplifying circuits comprising an inductor circuit and a switching circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, the switching circuit comprising eight switching tubes and four diodes, each of the four switching tubes being connected in series to form bridge arms, two bridge arms being connected in parallel to one side of the output capacitor circuit, each of the two diodes being connected in series and in parallel to the two switching tubes located in the middle of a bridge arm,and wherein a connection point between the two series-connected diodes is connected to the output capacitor circuit, wherein the same-name end of the primary winding of the self-coupling inductor and the unlike-name end of the secondary winding are connected to one end of the first inductor, and while the same-name end of the primary winding of the self-coupling inductor and the same-name end of the secondary winding are each connected to the midpoint of a bridge arm, wherein the other side of the output capacitor circuit serves as the second external side of the three-phase bidirectional AC-DC converter circuit, and while the other end of the first inductor in three boosting circuits serves as the first external side of the three-phase bidirectional AC-DC converter circuit.

[0006] As a further technical solution, the output capacitor circuit comprises a fourth capacitor and a fifth capacitor, the fourth capacitor and the fifth capacitor being connected in series and in parallel with the bridge arm of the three amplification circuits, the connection point between the fourth capacitor and the fifth capacitor being the midpoint of the output capacitor circuit and being connected at the connection point between two series-connected diodes.

[0007] As a further technical solution, the three-phase bidirectional AC-DC converter circuit further comprises an EMI filter circuit, the EMI filter circuit comprising a first capacitor, a second capacitor, and a third capacitor, the first capacitor, the second capacitor, and the third capacitor being each connected in parallel between the first external side of the three-phase bidirectional AC-DC converter circuit and the midpoint of the output capacitor circuit.

[0008] As a further technical solution, the switching tube can be made of a MOSFET, an IGBT tube, a GaN tube or a SiC power tube.

[0009] To solve the technical problem, the present application further provides a three-phase bidirectional AC-DC converter circuit comprising three boosting circuits having the same structure and an output capacitor circuit, each of the boosting circuits comprising an inductor circuit and a switch circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, the switch circuit comprising four switching tubes, a first bidirectional switch, and a second bidirectional switch, and each of the two switching tubes is connected in series to form bridge arms, two bridge arms being connected in parallel to one side of the output capacitor circuit, the same end of the primary winding of the self-coupling inductor and the opposite end of the secondary winding being connected to one end of the first inductor,while the opposite end of the primary winding of the self-coupling inductor and the like end of the secondary winding are connected to the first bidirectional switch and the second bidirectional switch, respectively, and the other ends of the first bidirectional switch and the second bidirectional switch are connected to the output capacitor circuit, the midpoints of the two bridge arms being connected to the connection node between the self-coupling inductor and the first bidirectional switch and to the connection node between the self-coupling inductor and the second bidirectional switch, respectively, and the other side of the output capacitor circuit serving as the second external side of the three-phase bidirectional AC-DC converter circuit,and while the other end of the first inductor in three amplification circuits serves as the first external side of the three-phase bidirectional AC-DC converter circuit.,

[0010] To solve the technical problem, the present application provides a three-phase bidirectional AC-DC converter circuit comprising three amplifying circuits having the same structure and an output capacitor circuit, wherein each of the amplifying circuits comprises an inductor circuit and a switching circuit, wherein the inductor circuit comprises a first inductor and a self-coupling inductor, and the switching circuit comprises four switching tubes, wherein each of the two switching tubes is connected in series to form bridge arms, and wherein the two bridge arms are connected in parallel to one side of the output capacitor circuit, and wherein the like end of the primary winding of the self-coupling inductor and the unlike end of the secondary winding are connected to one end of the first inductor,and while the unlike end of the primary winding of the self-coupling inductor and the like end of the secondary winding are each connected to the midpoint of one of the bridge arms, the other side of the output capacitor circuit serving as the second external side of the three-phase bidirectional AC-DC converter circuit, and while the other end of the first inductor in three boosting circuits serving as the first external side of the three-phase bidirectional AC-DC converter circuit.

[0011] As a further technical solution, the output capacitor circuit comprises a sixth capacitor, wherein the sixth capacitor is connected in parallel to bridge branches of the three amplification circuits.

[0012] Compared with the prior art, in the three-phase bidirectional AC-DC converter circuit of the present application, the switching tubes of the amplifier circuit can realize bidirectional power flow, the three amplifier circuits adopt three-phase interleaved technology, the three-phase input and output currents are different by 120°, and the input and output current fluctuations of the three-phase amplifier circuits complement each other, so that the input and output voltage and current ripple of the three-phase bidirectional AC-DC converter circuits are small, thus achieving good circuit performance.Each amplifier circuit is equipped with a first inductor and a self-coupling inductor. Parallel interleaving improves the switching frequency, achieves low-cost filtering, reduces control difficulty, and further reduces input and output voltage and current ripple. The interleaved arrangement of each amplifier circuit also ensures that the two branches containing the self-coupling inductor achieve current balance regardless of the power flow direction (forward or reverse). This prevents uneven heating of the components in the branches and ensures reliable circuit operation. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic circuit diagram of a first embodiment of a three-phase bidirectional AC-DC converter circuit of the present application. Fig. 2 is a schematic circuit diagram of a second embodiment of a three-phase bidirectional AC-DC converter circuit of the present application. Fig. 3 is a schematic circuit diagram of a third embodiment of a three-phase bidirectional AC-DC converter circuit of the present application. DETAILED DESCRIPTION

[0013] In order for a person skilled in the art to better understand the purpose, technical solutions and advantages of the present application, the present application is explained in more detail below in conjunction with the attached drawings and embodiments.

[0014] As in Fig. 1, is Fig. 1 is a schematic circuit diagram of a first embodiment of a three-phase bidirectional AC-DC converter circuit of the present application. In the embodiment shown in the attached drawings, the three-phase bidirectional AC-DC converter circuit 10 comprises three boosting circuits of the same structure and an output capacitor circuit, each of the boosting circuits comprising an inductor circuit and a switching circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, the switching circuit comprising eight switching tubes and four diodes, each of the four switching tubes being connected in series to form bridge arms, two bridge arms being connected in parallel to one side of the output capacitor circuit, each of the two diodes being connected in series and to the two switching tubes,which are located in the middle of a bridge arm, are connected in parallel, and a connection point between the two series-connected diodes is connected to the output capacitor circuit, the same end of the primary winding of the self-coupling inductor and the unlike end of the secondary winding are connected to one end of the first inductor, and the same end of the primary winding of the self-coupling inductor and the same end of the secondary winding are each connected to the midpoint of a bridge arm, the other side of the output capacitor circuit serving as the second external side of the three-phase bidirectional AC-DC converter circuit 10, and the other end of the first inductor in three amplification circuits serving as the first external side of the three-phase bidirectional AC-DC converter circuit 10. It is understandable,that both the first external side and the second external side in the three-phase bidirectional AC-DC converter circuit 10 of the present application can be connected to a load and an AC power source. The first external side can be connected to the AC power source when used as the AC power side, and its second external side can be externally connected to the load when used as the DC output side. When the second external side is used as the AC power side, the AC power source can be externally connected, and its first external side is used as the DC output side, which can be externally connected to the load. Based on the above design, each boosting circuit is equipped with a first inductor and a self-coupling inductor, thereby improving the switching frequency.Cost-effective filtering can be achieved and the difficulty of control can be reduced through a nested parallel connection, as well as reducing the load and the input and output voltage and current ripple. The three boost circuits use three-phase nesting technology. The three-phase input and output currents differ by 120°, and the input and output current fluctuations of the three-phase boost circuit are complementary, which further reduces the input and output current ripple of the three-phase bidirectional AC-DC converter circuit 10. Furthermore, the nested arrangement and manner can ensure that the two branches in which the self-coupling inductor is located achieve current balance regardless of the power flow direction (forward or reverse), and can prevent the branch from uneven heating to preventthat the branch current unevenly triggers overcurrent protection, so that the circuit can work normally, thus achieving the purpose of improving the performance of the circuit.

[0015] Specifically, in this embodiment, the three amplification circuits having the same structure are a first amplification circuit, a second amplification circuit, and a third amplification circuit, respectively, wherein the inductor circuit in the first amplification circuit includes a first inductor L1 and a self-coupling inductor L2, and wherein the switching circuit includes a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7, an eighth switching tube Q8, a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4, and wherein the midpoint of a bridge arm formed by the series connection of the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4,connected to the opposite end of the primary winding of the self-coupling inductor L2. In the bridge arm, the third switching tube Q3 and the fourth switching tube Q4 are located in the middle, and the first diode D1 and the second diode D2 are connected in series and then in parallel with the third switching tube Q3 and the fourth switching tube Q4. The junction point between the first diode D1 and the second diode D2 is connected to an output capacitor circuit. That is, the anode of the first diode D1 and the cathode of the second diode D2 are both connected to the output capacitor circuit after they are connected. The midpoint of the bridge arm, formed by the series connection of the fifth switching tube Q5, the sixth switching tube Q6, the seventh switching tube Q7, and the eighth switching tube Q8, is connected to the same end of the secondary winding of the self-coupling inductor L2.The seventh switching tube Q7 and the eighth switching tube Q8 are located in the middle of this bridge arm. A third diode D3 and a fourth diode D4 are connected in series and then parallel to the seventh switching tube Q7 and the eighth switching tube Q8. The junction point between the third diode D3 and the fourth diode D4 is connected to the output capacitor circuit. That is, the anode of the third diode D3 and the cathode of the fourth diode D4 are both connected to the output capacitor circuit after they are connected.

[0016] The inductor circuit in the second amplification circuit includes a first inductor L3 and a self-coupling inductor L4, and the switching circuit includes a ninth switching tube Q9, a tenth switching tube Q10, an eleventh switching tube Q11, a twelfth switching tube Q12, a thirteenth switching tube Q13, a fourteenth switching tube Q14, a fifteenth switching tube Q15, a sixteenth switching tube Q16, a fifth diode D5, a sixth diode D6, a seventh diode D7, and an eighth diode D8. The midpoint of a bridge arm formed by the series connection of the ninth switching tube Q9, the tenth switching tube Q10, the eleventh switching tube Q11 and the twelfth switching tube Q12 is connected to the unlike end of the primary winding of the self-coupling inductor L4, and the eleventh switching tube Q11 and the twelfth switching tube Q12 are located in the middle of this bridge arm.A fifth diode D5 and a sixth diode D6 are connected in series and then connected in parallel with the eleventh switching tube Q11 and the twelfth switching tube Q12. The junction point between the fifth diode D5 and the sixth diode D6 is connected to an output capacitor circuit. That is, the anode of the fifth diode D5 and the cathode of the sixth diode D6 are both connected to the output capacitor circuit after connection. The midpoint of a bridge arm formed by the series connection of the thirteenth switching tube Q13, the fourteenth switching tube Q14, the fifteenth switching tube Q15, and the sixteenth switching tube Q16 is connected to the like-end of the secondary winding of the self-coupling inductor L4. The fifteenth switching tube Q15 and the sixteenth switching tube Q16 are located in the middle of this bridge arm.A seventh diode D7 and an eighth diode D8 are connected in series and then connected in parallel with the fifteenth switching tube Q15 and the sixteenth switching tube Q16 which are connected in series, and the connection point between the seventh diode D7 and the eighth diode D8 is connected to an output capacitor circuit, that is, the anode of the seventh diode D7 and the cathode of the eighth diode D8 are both connected to the output capacitor circuit after being connected.

[0017] The inductor circuit in the third amplification circuit comprises a first inductor L5 and a self-coupling inductor L6, wherein the switching circuit comprises a seventeenth switching tube Q17, an eighteenth switching tube Q18, a nineteenth switching tube Q19, a twentieth switching tube Q20, a twenty-first switching tube Q21, a twenty-second switching tube Q22, a twenty-third switching tube Q23, a twenty-fourth switching tube Q24, a ninth diode D9, a tenth diode D10, an eleventh diode D11 and a twelfth diode D12, wherein the midpoint of a bridge arm formed by the series connection of the seventeenth switching tube Q17, the eighteenth switching tube Q18, the nineteenth switching tube Q19 and the twentieth switching tube Q20 is connected to the opposite end of the primary winding of the self-coupling inductor L6, the nineteenth switching tube Q19 and the twentieth switching tube Q20 are located in the middle of the bridge branch.A ninth diode D9 and a tenth diode D10 are connected in series and then connected in parallel with the nineteenth switching tube Q19 and the twentieth switching tube Q20. The junction point between the ninth diode D9 and the tenth diode D10 is connected to an output capacitor circuit. That is, the anode of the ninth diode D9 and the cathode of the tenth diode D10 are both connected to the output capacitor circuit after connection. The midpoint of a bridge arm formed by the series connection of the twenty-first switching tube Q21, the twenty-second switching tube Q22, the twenty-third switching tube Q23, and the twenty-fourth switching tube Q24 is connected to the like-named end of the secondary winding of the self-coupling inductor L4. The twenty-third switching tube Q23 and the twenty-fourth switching tube Q24 are located at the center of this bridge arm.An eleventh diode D11 and a twelfth diode D12 are connected in series and then in parallel with the series-connected twenty-third switching tube Q23 and the twenty-fourth switching tube Q24, and the connection point between the eleventh diode D11 and the twelfth diode D12 is connected to the output capacitor circuit, that is, the anode of the eleventh diode D11 and the cathode of the twelfth diode D12 are connected to the output capacitor circuit.

[0018] Preferably, the switching tubes are selectively made of MOS, IGBT, GaN, SiC, or other controllable power switching tubes to achieve better circuit performance. When the switching tube is selected as a MOS tube, a diode is connected in parallel between the drain and source, and when the switching tube is selected as an IGBT, a diode is connected in parallel between the emitter and collector. Furthermore, in the present embodiment, a PFM method is adopted to control the operation of the switching tube. That is, a constant duty cycle is adopted to keep the on- and off-time of the switching tube constant, and then the frequency of the square wave is modulated to achieve closed-loop control to realize currentless turn-on of the three-phase bidirectional AC-DC converter circuit 10 in a low-frequency operating state.

[0019] In some embodiments, the output capacitor circuit includes a fourth capacitor C4 and a fifth capacitor C5, wherein the fourth capacitor C4 and the fifth capacitor C5 are connected in series and in parallel with the bridge leg of the three amplification circuits. The connection point of the fourth capacitor C4 and the fifth capacitor C5 is the midpoint of the output capacitor circuit and connects the connection points between a first diode D1 and a second diode D2, a third diode D3 and a fourth diode D4, a fifth diode D5 and a sixth diode D6, a seventh diode D7 and an eighth diode D8, a ninth diode D9 and a tenth diode D10, an eleventh diode D11 and a twelfth diode D12, which are connected in series.

[0020] Furthermore, the three-phase bidirectional AC-DC converter circuit 10 in this embodiment further includes an EMI filter circuit 13, wherein the EMI filter circuit 13 includes a first capacitor C1, a second capacitor C2, and a third capacitor C3. The first capacitor C1, the second capacitor C2, and the third capacitor C3 are each connected in parallel between a first external side of the three-phase bidirectional AC-DC converter circuit 10 and a midpoint of the output capacitor circuit. Based on the above design, the added EMI filter circuit 13 ensures that the common-mode noise of the entire three-phase bidirectional AC-DC converter circuit 10 has a bypass channel, which greatly reduces the common-mode noise, facilitates the suppression of electromagnetic interference, and improves the reliability of the circuit.

[0021] As in Fig. 2, is Fig. 2 is a schematic circuit diagram of a second embodiment of a three-phase bidirectional AC-DC converter circuit of the present application. This embodiment differs from the first embodiment described above in that the specific structure of the switching circuit in the booster circuit is different, while the remaining structures are similar or identical. In this embodiment, the switching circuit includes four switching tubes, a first bidirectional switch and a second bidirectional switch, each of the two switching tubes being connected in series to form a bridge arm, and the two bridge arms being connected in parallel to one side of the output capacitor circuit.The same end of the primary winding of the self-coupling inductor and the opposite end of the secondary winding are connected to one end of the first inductor, and the same end of the primary winding of the self-coupling inductor and the same end of the secondary winding are connected to the first bidirectional switch and the second bidirectional switch, respectively. The other ends of the first bidirectional switch and the second bidirectional switch are connected to the output capacitor circuit, and the midpoints of the two bridge arms are connected to the connection points between the self-coupling inductor and the first bidirectional switch and the connection points between the self-coupling inductor and the second bidirectional switch, respectively. The present embodiment also achieves good circuit performance.

[0022] Specifically, in this embodiment, the switching circuit in the first amplification circuit includes a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a first bidirectional switch S1, and a second bidirectional switch S2.The midpoint of a bridge arm formed by the series connection of the first switching tube Q1 and the second switching tube Q2 is connected to a connection node between the first bidirectional switch S1 and the opposite end of the primary winding of the self-coupling inductor L2, and the midpoint of a bridge arm formed by the series connection of the third switching tube Q3 and the fourth switching tube Q4 is connected to a connection node between the second bidirectional switch S2 and the opposite end of the secondary winding of the self-coupling inductor L2, and the first bidirectional switch S1 and the second bidirectional switch S2 are both connected to the midpoint of the output capacitor circuit.The switching circuit in the second amplification circuit includes a first switching tube Q21, a second switching tube Q22, a third switching tube Q23, a fourth switching tube Q24, a first bidirectional switch S3 and a second bidirectional switch S4.The midpoint of a bridge arm formed by the series connection of the first switching tube Q21 and the second switching tube Q22 is connected to a connection node between the first bidirectional switch S3 and the opposite end of the primary winding of the self-coupling inductor L4, and the midpoint of a bridge arm formed by the series connection of the third switching tube Q23 and the fourth switching tube Q24 is connected to a connection node between the second bidirectional switch S4 and the opposite end of the secondary winding of the self-coupling inductor L4, and both the first bidirectional switch S3 and the second bidirectional switch S4 are connected to the midpoint of the output capacitor circuit.The switching circuit in the third amplification circuit includes a first switching tube Q31, a second switching tube Q32, a third switching tube Q33, a fourth switching tube Q34, a first bidirectional switch S5 and a second bidirectional switch S6.The midpoint of a bridge arm formed by the series connection of the first switching tube Q31 and the second switching tube Q32 is connected to a connection node between the first bidirectional switch S5 and the opposite end of the primary winding of the self-coupling inductor L6, and the midpoint of a bridge arm formed by the series connection of the third switching tube Q33 and the fourth switching tube Q34 is connected to a connection node between the second bidirectional switch S6 and the opposite end of the secondary winding of the self-coupling inductor L6, and both the first bidirectional switch S5 and the second bidirectional switch S6 are connected to the midpoint of the output capacitor circuit.

[0023] As in Fig. 3, is Fig.3 is a schematic circuit diagram of a third embodiment of a three-phase bidirectional AC-DC converter circuit of the present application. The difference between this embodiment and the first embodiment described above is that the specific structures of the switching circuit and the output capacitor circuit are not connected to each other. In this embodiment, the switching circuit includes four switching tubes. Two switching tubes are connected in series to form bridge arms. Two bridge arms are connected in parallel to the output capacitor circuit side. The same end of the primary winding of the self-coupling inductor and the opposite end of the secondary winding are connected to the end of the first inductor.The unlike end of the primary winding and the like end of the secondary winding of the self-coupling inductor are connected to the midpoint of a bridge arm, and the output capacitor circuit includes a sixth capacitor C6 connected in parallel to the bridge arm of the three amplification circuits.

[0024] Specifically, in this embodiment, the switching circuit in the first amplification circuit includes a first switching tube Q41, a second switching tube Q42, a third switching tube Q43, and a fourth switching tube Q44, and the midpoint of the bridge arm formed by the series connection of the first switching tube Q41 and the second switching tube Q42 is connected to the same end of the primary winding of the self-coupling inductor L2, the midpoint of the bridge arm formed by the series connection of the third switching tube Q43 and the fourth switching tube Q44 is connected to the same end of the secondary winding of the self-coupling inductor L2.The switching circuit in the second amplification circuit comprises a first switching tube Q51, a second switching tube Q52, a third switching tube Q53 and a fourth switching tube Q54, wherein the midpoint of the bridge arm formed by the series connection of the first switching tube Q51 and the second switching tube Q52 is connected to the same end of the primary winding of the self-coupling inductor L4, the midpoint of the bridge arm formed by the series connection of the third switching tube Q53 and the fourth switching tube Q54 is connected to the same end of the secondary winding of the self-coupling inductor L4.The switching circuit in the third amplification circuit includes a first switching tube Q61, a second switching tube Q62, a third switching tube Q63, and a fourth switching tube Q64. The midpoint of the bridge arm formed by the series connection of the first switching tube Q61 and the second switching tube Q62 is connected to an unlike end of the primary winding of the self-coupling inductor L6, and the midpoint of the bridge arm formed by the series connection of the third switching tube Q63 and the fourth switching tube Q64 is connected to the like end of the secondary winding of the self-coupling inductor L6.

[0025] In summary, in the three-phase bidirectional AC-DC converter circuit of the present application, the switching tubes of the amplifier circuit can realize bidirectional power flow. The three amplifier circuits use three-phase interleaved technology. The three-phase input and output currents differ by 120°, and the input and output current fluctuations of the three-phase amplifier circuits complement each other, so the input and output voltage and current ripple of the three-phase bidirectional AC-DC converter circuits are small, thus achieving good circuit performance. Each amplifier circuit consists of parallel-connected amplifier circuits whose two phases have the same frequency and a phase difference of 180°.The boost circuit uses a three-inductor structure formed by the first inductor and the self-coupling inductor. This interleaving improves the switching frequency, achieves low-cost filtering, reduces control difficulty, and further reduces input and output voltage and current ripple. It also ensures that the two branches containing the self-coupling inductor achieve current balance regardless of the power flow direction (forward or reverse). This prevents uneven heating of the components in the branches and ensures reliable circuit operation.

[0026] The foregoing is only a preferred embodiment of the present application and does not constitute a limitation of the present application in any way. Those skilled in the art can make various equivalent changes and improvements based on the above embodiments, and all equivalent changes or modifications made within the scope of the claims are within the scope of the present application. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] CN 202211104497.2

[0001]

Claims

[1] Three-phase bidirectional AC-DC converter circuit, characterized bythat the three-phase bidirectional AC-DC converter circuit comprises three amplification circuits of the same structure and an output capacitor circuit, each of the amplification circuits comprising an inductor circuit and a switch circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, the switch circuit comprising eight switching tubes and four diodes, each of the four switching tubes being connected in series to form bridge arms, two bridge arms being connected in parallel to one side of the output capacitor circuit, each of the two diodes being connected in series and in parallel to the two switching tubes located in the middle of a bridge arm, and a connection point between the two series-connected diodes being connected to the output capacitor circuit,wherein the like end of the primary winding of the self-coupling inductor and the unlike end of the secondary winding are connected to one end of the first inductor, and while the like end of the primary winding of the self-coupling inductor and the like end of the secondary winding are each connected to the midpoint of a bridge arm, the other side of the output capacitor circuit serving as the second external side of the three-phase bidirectional AC-DC converter circuit, and while the other end of the first inductor in three boosting circuits serves as the first external side of the three-phase bidirectional AC-DC converter circuit. [2] Three-phase bidirectional AC-DC converter circuit according to claim 1, characterized bythat the output capacitor circuit comprises a fourth capacitor and a fifth capacitor, the fourth capacitor and the fifth capacitor being connected in series and in parallel with the bridge arm of the three amplification circuits, the connection point between the fourth capacitor and the fifth capacitor being the midpoint of the output capacitor circuit and being connected at the connection point between two series-connected diodes. [3] Three-phase bidirectional AC-DC converter circuit according to claim 2, characterized bythat the three-phase bidirectional AC-DC converter circuit further comprises an EMI filter circuit, the EMI filter circuit comprising a first capacitor, a second capacitor and a third capacitor, the first capacitor, the second capacitor and the third capacitor each being connected in parallel between the first external side of the three-phase bidirectional AC-DC converter circuit and the midpoint of the output capacitor circuit. [4] Three-phase bidirectional AC-DC converter circuit according to claim 1, characterized by that the switching tube consists optionally of a MOSFET, an IGBT tube, a GaN tube or a SiC power tube. [5] Three-phase bidirectional AC-DC converter circuit, characterized bythat the three-phase bidirectional AC-DC converter circuit comprises three amplification circuits with the same structure and an output capacitor circuit, each of the amplification circuits comprising an inductor circuit and a switch circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, the switch circuit comprising four switching tubes, a first bidirectional switch and a second bidirectional switch, and each of the two switching tubes is connected in series to form bridge arms, two bridge arms being connected in parallel to one side of the output capacitor circuit, the like end of the primary winding of the self-coupling inductor and the unlike end of the secondary winding being connected to one end of the first inductor,while the opposite end of the primary winding of the self-coupling inductor and the like end of the secondary winding are connected to the first bidirectional switch and the second bidirectional switch, respectively, and the other ends of the first bidirectional switch and the second bidirectional switch are connected to the output capacitor circuit, the midpoints of the two bridge arms being connected to the connection node between the self-coupling inductor and the first bidirectional switch and to the connection node between the self-coupling inductor and the second bidirectional switch, respectively, and the other side of the output capacitor circuit serving as the second external side of the three-phase bidirectional AC-DC converter circuit,and while the other end of the first inductor in three amplification circuits serves as the first external side of the three-phase bidirectional AC-DC converter circuit., [6] Three-phase bidirectional AC-DC converter circuit, characterized bythat the three-phase bidirectional AC-DC converter circuit comprises three amplification circuits of the same structure and an output capacitor circuit, each of the amplification circuits comprising an inductor circuit and a switch circuit, the inductor circuit comprising a first inductor and a self-coupling inductor, and the switch circuit comprising four switching tubes, each of the two switching tubes being connected in series to form bridge arms, and the two bridge arms being connected in parallel to one side of the output capacitor circuit, and the like-end of the primary winding of the self-coupling inductor and the unlike-end of the secondary winding being connected to one end of the first inductor,and while the unlike end of the primary winding of the self-coupling inductor and the like end of the secondary winding are each connected to the midpoint of one of the bridge arms, the other side of the output capacitor circuit serving as the second external side of the three-phase bidirectional AC-DC converter circuit, and while the other end of the first inductor in three boosting circuits serving as the first external side of the three-phase bidirectional AC-DC converter circuit. [7] Three-phase bidirectional AC-DC converter circuit according to claim 6, characterized by that the output capacitor circuit comprises a sixth capacitor, wherein the sixth capacitor is connected in parallel to bridge branches of the three amplification circuits.

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