A three-phase interleaved wide-range high-efficiency isolated bidirectional converter

Abstract

The application discloses a three-phase staggered wide-range high-efficiency isolated bidirectional converter, which comprises a three-phase bridge switching circuit, a resonance cavity, three transformers and a three-phase bridge rectifier circuit. The resonance cavity comprises three resonance circuits. Each resonance circuit comprises a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor and a third inductor. One end of the first inductor is connected to one end of the second inductor, the first capacitor and the third capacitor. The other end of the first inductor and the first capacitor is respectively connected to one end of the third inductor and the second capacitor. The one end of the third inductor is connected to the midpoint of one bridge arm of the three-phase bridge switching circuit. The other end of the second inductor and the third capacitor is respectively connected to the other end of the third inductor and the second capacitor and connected to the primary winding of a transformer. The one end of the second capacitor and the first capacitor of the three resonance circuits is respectively connected to each other to form a Y-type connection. The secondary windings of the three transformers are respectively connected to the midpoints of the three bridge arms of the three-phase bridge rectifier circuit.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power conversion, more particularly to a three-phase interleaved wide-range high-efficiency isolated bidirectional converter. BACKGROUND

[0002] DC-DC bidirectional converter is a DC / DC converter capable of adjusting the bidirectional transmission of energy as needed, which is mainly used in energy storage systems, vehicle power systems, feedback charging and discharging systems, hybrid energy electric vehicles and other occasions. With the continuous development of the industry, the power is continuously increasing from kilowatt to tens of kilowatts, and the topology capable of realizing large power, wide range, positive and negative symmetric bidirectional, high efficiency has become the general trend.

[0003] In the traditional LLC resonant bidirectional converter, the ZVS conduction of the primary side switch tube and the ZCS conduction of the rectification side diode can be realized whether in forward or reverse direction. However, when the energy flows in the reverse direction, the circuit characteristic is no longer LLC resonance characteristic but LC resonance characteristic, and the maximum voltage gain of LC resonance becomes 1, which greatly reduces the voltage gain in the reverse direction, and cannot realize normal output in the reverse direction, so that the forward and reverse directions are not completely symmetric bidirectional. In order to realize completely symmetric bidirectional energy flow, DAB or a one-stage topology circuit is added based on LLC to make up for the insufficient reverse gain of LLC, and completely symmetric bidirectional is basically realized. However, DAB hard switching and LLC two-stage topology architecture will bring about the problem of low efficiency, especially for larger power bidirectional DC-DC, due to the inherent problems of DAB or two-stage topology, the heat and ripple of large power bidirectional DC-DC will become more and more difficult to handle as the power increases, which will eventually become a bottleneck. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a three-phase interleaved wide-range high-efficiency isolated bidirectional converter which can reduce ripple and realize wide range, completely symmetric positive and negative gain and high efficiency.

[0005] To solve the above technical problems, the present application provides a three-phase interleaved wide-range high-efficiency isolated bidirectional converter, which comprises a three-phase bridge switching circuit, a resonant cavity, three transformers and a three-phase bridge rectifier circuit. One side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit is respectively connected to the first connection side and the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter. The resonant cavity comprises three resonant circuits, each of which is connected between the midpoint of the three bridge arms of the three-phase bridge switching circuit and the primary winding of the three transformers.

[0006] The resonant circuit comprises a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor and a third inductor, one end of the first inductor is connected to one end of the second inductor, the first capacitor and the third capacitor, the other end of the first inductor and the first capacitor is connected to one end of the third inductor and the second capacitor respectively, the one end of the third inductor is connected to the midpoint of a bridge arm in the three-phase bridge switching circuit, the other end of the second inductor and the third capacitor is connected to the other end of the third inductor and the second capacitor respectively, and is connected to the primary winding of a transformer, and the one end of the second capacitor and the first capacitor in the three resonant circuits is connected to each other to form a Y-type connection, and the same name end of the three transformer secondary windings is connected to the midpoint of the three bridge arms of the three-phase bridge rectifier circuit respectively, and the different name end of the three transformer secondary windings is connected to each other to form a Y-type connection.

[0007] Further technical solutions are that the three-phase bridge switching circuit comprises six switch tubes, and every two switch tubes are connected in series to form a bridge arm, and the three bridge arms are connected in parallel, and the two ends thereof are used as the first connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter.

[0008] Further technical solutions are that the three-phase bridge rectifier circuit comprises six switch tubes, and every two switch tubes are connected in series to form a bridge arm, and the three bridge arms are connected in parallel, and the two ends thereof are used as the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter.

[0009] Further technical solutions are that the switch tubes are selected from MOSFET, IGBT tube, GaN tube or SiC power tube.

[0010] Further technical solutions are that the three-phase interleaved wide-range high-efficiency isolated bidirectional converter further comprises a first filter capacitor and a second filter capacitor, the two ends of the first filter capacitor are connected to the first connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter, and the two ends of the second filter capacitor are connected to the second connection side.

[0011] To solve the above technical problems, the application further provides a three-phase interleaved wide-range high-efficiency isolated bidirectional converter, comprising a three-phase bridge switching circuit, a resonant cavity, three transformers and a three-phase bridge rectifier circuit, one side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit is used as the first connection side and the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter respectively, the resonant cavity comprises three resonant circuits, and the three resonant circuits are connected between the midpoints of the three bridge arms of the three-phase bridge switching circuit and the primary windings of the three transformers respectively, wherein,

[0012] The resonant circuit comprises a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor and a third inductor, one end of the first inductor is connected to one end of the second inductor, the first capacitor and the third capacitor, the other end of the first inductor and the first capacitor is connected to one end of the third inductor and the second capacitor respectively, the one end of the second capacitor is connected to the midpoint of one bridge arm in the three-phase bridge switching circuit, the other end of the second inductor and the third capacitor is connected to the other end of the third inductor and the second capacitor respectively, and the primary winding of a transformer, and the one end of the third inductor and the first inductor in the three resonant circuits is connected to each other to form a Y-type connection, and the same name end of the three transformer secondary windings is connected to the midpoint of the three bridge arms of the three-phase bridge rectifier circuit respectively, and the different name end of the three transformer secondary windings is connected to each other to form a Y-type connection.

[0013] To solve the above technical problems, the application further provides a three-phase staggered wide-range high-efficiency isolated bidirectional converter, comprising a three-phase bridge switching circuit, a resonant cavity, three transformers and a three-phase bridge rectifier circuit, one side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit is respectively used as the first connection side and the second connection side of the three-phase staggered wide-range high-efficiency isolated bidirectional converter, the resonant cavity comprises three resonant circuits, and the three resonant circuits are respectively connected between the midpoint of the three bridge arms of the three-phase bridge switching circuit and the primary winding of the three transformers, wherein,

[0014] The resonant circuit comprises a first capacitor, a second capacitor, a first inductor, a second inductor and a third inductor, one end of the first inductor and the second inductor is connected to one end of the first capacitor and the second capacitor, the other end of the first inductor is connected to one end of the third inductor, and the other end of the second inductor and the second capacitor is connected to the primary winding of a transformer, and the other end of the second inductor is connected to the other end of the third inductor, the other end of the first capacitor in the three resonant circuits is connected to each other to form a Y-type connection, and the same name end of the three transformer secondary windings is connected to the midpoint of the three bridge arms of the three-phase bridge rectifier circuit respectively, and the different name end of the three transformer secondary windings is connected to each other to form a Y-type connection.

[0015] To solve the above technical problems, the application further provides a three-phase staggered wide-range high-efficiency isolated bidirectional converter, comprising a three-phase bridge switching circuit, a resonant cavity, three transformers and a three-phase bridge rectifier circuit, one side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit is respectively used as the first connection side and the second connection side of the three-phase staggered wide-range high-efficiency isolated bidirectional converter, the resonant cavity comprises three resonant circuits, and the three resonant circuits are respectively connected between the midpoint of the three bridge arms of the three-phase bridge switching circuit and the primary winding of the three transformers, wherein,

[0016] The resonant circuit comprises a first capacitor, a second capacitor, a first inductor, a second inductor and a third inductor, one end of the first inductor is connected with the first capacitor and one end of the third inductor, one end of the second inductor is connected with the other end of the third inductor and one end of the second capacitor, the other end of the first capacitor is connected with the midpoint of one bridge arm in the three-phase bridge switching circuit, the other end of the second inductor and the second capacitor is connected with the primary winding of a transformer, and the other end of the second inductor is connected with the other end of the first inductor, the same name ends of three secondary windings of the transformer are respectively connected with the midpoints of three bridge arms of the three-phase bridge rectifier circuit, and the different name ends of the three primary windings and the three secondary windings of the transformer are respectively connected with each other to form a Y-type connection.

[0017] Compared with the prior art, the three-phase interleaved wide-range high-efficiency isolated bidirectional converter can reduce the ripple by adopting the three-phase interleaved technology, the equivalent circuit of the resonant circuit in the energy forward and reverse flow is a multi-element resonant circuit, the soft switching is realized in the forward and reverse operation, the loss is small, the problem that the traditional LLC resonant circuit cannot work in the reverse direction with the same performance is solved, that is, the three-phase interleaved wide-range high-efficiency isolated bidirectional converter can step up when the energy flows in the reverse direction, the input and output voltage range of the converter can be effectively improved, the wide voltage range output is realized, the gain is the same when the energy flows in the forward and reverse directions, and the structure design of the resonant circuit can realize the wide voltage range output without wide frequency control when the switching frequency control is adopted, that is, the switching control frequency can be compressed to be narrow, and the efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the circuit schematic diagram of the first embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter.

[0019] Figure 2 is the circuit schematic diagram of the second embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter.

[0020] Figure 3 is the circuit schematic diagram of the third embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter.

[0021] Figure 4 is the circuit schematic diagram of the fourth embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter. DETAILED DESCRIPTION

[0022] In order for those skilled in the art to more clearly understand the purpose, technical scheme and advantages of the present application, the present application will be further described below in conjunction with the drawings and embodiments.

[0023] REFERENCE Figure 1 , Figure 1The circuit schematic diagram of the first embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 of the present application. In the embodiment shown in the drawing, the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 comprises a three-phase bridge switching circuit 100, a resonant cavity 200, three transformers, and a three-phase bridge rectifier circuit 300, one side of the three-phase bridge switching circuit 100 and the three-phase bridge rectifier circuit 300 respectively serving as the first connection side and the second connection side of the converter 10 to connect the power supply or the load, and the resonant cavity 200 comprising three resonant circuits, each corresponding to the connection between the midpoint of a three-phase bridge switching circuit 100 and the primary winding of a transformer. Among them, the resonant circuit comprises a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor, and a third inductor, one end of the first inductor being connected to one end of the second inductor, the first capacitor, and the third capacitor, the other end of the first inductor and the first capacitor being connected to one end of the third inductor and the second capacitor respectively, the other end of the third inductor being connected to the midpoint of a bridge arm in the three-phase bridge switching circuit 100, the other end of the second inductor and the third capacitor being connected to the other end of the third inductor and the second capacitor respectively, and the primary winding of a transformer, and the ends of the second capacitor and the first capacitor connected in the three resonant circuits being connected to each other to form a Y-type connection, the same-named ends of the secondary windings of the three transformers being connected to the midpoints of the three bridge arms of the three-phase bridge rectifier circuit 300 respectively, and the different-named ends of the secondary windings of the three transformers being connected to each other to form a Y-type connection. Preferably, the inductance of the first inductor and the second inductor in the resonant circuit is the same, and the capacitance of the first capacitor and the third capacitor is the same. Understandably, the Y-type connection is adopted in the resonant circuit, the total current flowing into the midpoint of the Y-type connection is equal to the total current flowing out of the midpoint of the Y-type connection, i.e., the sum of the currents of the three resonant circuits is "0", so at any moment, the current of one resonant circuit is always the sum of the currents of the other two resonant circuits, and therefore even if there is a certain tolerance in the resonant parameters of each resonant circuit, the effective value deviation of their currents is also very small, thereby ensuring the current balance among the three resonant circuits and avoiding the damage or overheating of the devices in a resonant circuit due to the excessive current in the resonant circuit.

[0024] Specifically, in the embodiment, the resonant cavity 200 includes a first resonant circuit, a second resonant circuit and a third resonant circuit, and the three transformers include a first transformer T1, a second transformer T2 and a third transformer T3. The first resonant circuit includes a first capacitor C1, a second capacitor C2, a third capacitor C3, a first inductor L1, a second inductor L2 and a third inductor L3. The second resonant circuit includes a first capacitor C4, a second capacitor C5, a third capacitor C6, a first inductor L4, a second inductor L5 and a third inductor L6. The third resonant circuit includes a first capacitor C7, a second capacitor C8, a third capacitor C9, a first inductor L7, a second inductor L8 and a third inductor L9. In the embodiment shown in the drawing, the third inductor L3, the third inductor L6 and the third inductor L9 correspond to the midpoints of the three bridge arms of the three-phase bridge-type switching circuit 100, respectively. The second capacitor C2, the second capacitor C5 and the second capacitor C8 are connected to each other to form a Y-type connection. The second inductor L2, the second inductor L5 and the second inductor L8 correspond to the same-name ends of the primary windings of the first transformer T1, the second transformer T2 and the third transformer T3, respectively. The third capacitor C3, the third capacitor C6 and the third capacitor C9 correspond to the different-name ends of the primary windings of the first transformer T1, the second transformer T2 and the third transformer T3, respectively.

[0025] In the embodiment, when the energy flows forward, i.e. the energy flows from the first connection side to the second connection side, the first connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 serves as a direct-current input end, and an external power supply can be connected thereto. The second connection side serves as a direct-current output end, and an external load can be connected thereto. When the energy flows reversely, i.e. the energy flows from the second connection side to the first connection side, the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 serves as a direct-current input end, and the first connection side serves as a direct-current output end. The three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 has a simple structure. When the energy flows forward and reversely, the equivalent circuits of the resonant circuits are multi-element resonant circuits, and soft switching can be realized in forward and reverse directions. The converter 10 has small loss and solves the problem of insufficient reverse gain of the traditional LLC resonant circuit. When the energy flows from the second connection side to the first connection side, the converter 10 can step up the voltage and effectively improve the input and output voltage range of the converter 10, so that wide voltage range input and output can be realized. The converter 10 can be applied to a high-power circuit. Compared with the three-phase interleaved bidirectional converter in the prior art, the switching frequency of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 needs to be controlled in a wide frequency range to realize wide voltage range input and output. The resonant frequency of the resonant circuit of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 is small, and when the switching frequency control is adopted, the switching frequency control does not need to be controlled in a wide frequency range to realize wide voltage range output. That is, the switching control frequency can be compressed and narrowed, and the efficiency is improved.

[0026] In some embodiments, the three-phase bridge switching circuit 100 includes six switching tubes, i.e., 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, and a sixth switching tube Q6. Each two switching tubes are connected in series to form a bridge arm. Three bridge arms are connected in parallel, and the two ends thereof serve as a first connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10. The midpoint of the bridge arm formed by the first switching tube Q1 and the second switching tube Q2 is connected to a first resonant circuit. The midpoint of the bridge arm formed by the third switching tube Q3 and the fourth switching tube Q4 is connected to a second resonant circuit. The midpoint of the bridge arm formed by the fifth switching tube Q5 and the sixth switching tube Q6 is connected to a third resonant circuit. In this embodiment, the switching tubes are controlled in a PFM mode, i.e., a constant duty cycle is adopted to achieve constant on and off time of the switching tubes, and then a modulation square wave frequency mode is adopted to achieve regulation. The switching frequency of the three-phase interleaved bidirectional converter in the prior art needs to be controlled in a wide frequency range to achieve voltage wide-range input and output. For example, when the voltage needs to be boosted from 40V to 400V, the switching frequency needs to be full load. The frequency is as high as 200KHZ in full load and 250KHZ in no load. However, the control range of the switching frequency of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 is relatively small. In the case of the same boost gain, the switching frequency is only 160KHZ in full load, and the efficiency is higher.

[0027] In the embodiment shown in the drawings, the three-phase bridge rectifier circuit 300 includes six switching tubes, i.e., a seventh switching tube Q7, an eighth switching tube Q8, a ninth switching tube Q9, a tenth switching tube Q10, an eleventh switching tube Q11, and a twelfth switching tube Q12. Each two switching tubes are connected in series to form a bridge arm. Three bridge arms are connected in parallel, and the two ends thereof serve as a second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10. The midpoint of the bridge arm formed by the seventh switching tube Q7 and the eighth switching tube Q8 is connected to a secondary winding of a first transformer T1. The midpoint of the bridge arm formed by the ninth switching tube Q9 and the tenth switching tube Q10 is connected to a secondary winding of a second transformer T2. The midpoint of the bridge arm formed by the eleventh switching tube Q11 and the twelfth switching tube Q12 is connected to a secondary winding of a third transformer T3. Based on this design, when the energy flows forward, the three-phase bridge rectifier circuit 300 can rectify the voltage waveform periodically output by the transformer to generate a working voltage required by the load. Preferably, the switching tubes can be MOSFET, IGBT tube, GaN tube, SiC power tube, or other controllable power switching tube to achieve better circuit performance. In some other embodiments, a diode can be connected in parallel to each switching tube.

[0028] Further, the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 further comprises a first filter capacitor C10 and a second filter capacitor C11, the first filter capacitor C10 is connected across the first connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10, and the second filter capacitor C11 is connected across the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10.

[0029] Understandably, in the embodiment, when the energy is transmitted forwardly, the wide-range voltage output of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 is realized by controlling the switching frequency of the first switch Q1, the second switch Q2, the third switch Q3, the fourth switch Q4, the fifth switch Q5 and the sixth switch Q6, and the two switches on each bridge arm are complementary to be turned on, so that the soft switching of the circuit can be realized; when the energy is transmitted reversely, the equivalent circuit of the resonant circuit is also a multi-element resonant circuit, therefore, the same wide-range voltage output as that in the forward transmission can be realized by controlling the switching frequency of the seventh switch Q7, the eighth switch Q8, the ninth switch Q9, the tenth switch Q10, the eleventh switch Q11 and the twelfth switch Q12, and the two switches on each bridge arm are complementary to be turned on, so that the soft switching of the circuit can be realized.

[0030] The three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 adopts the three-phase interleaved technology, the phase difference of the conduction of Q1 and Q2, Q3 and Q4, and Q5 and Q6 is 180 degrees, the conduction time sequence of Q1, Q3 and Q5 is different by 120 degrees; therefore, the conduction time sequence of Q2, Q4 and Q6 is also different by 120 degrees, the input and output current of the three-phase circuit is different by 120 degrees, the input and output current fluctuation of the three-phase circuit is complementary, so that the input and output current ripple is small, thereby realizing better circuit performance. At any moment, at least one to at most two of Q1, Q3 and Q5 are turned on, and the same is true for Q2, Q4 and Q6, and the number of the turned-on switches is always equal to three. Taking one of the three resonant circuits as an example, when Q1, Q4 and Q6 are turned on, the resonant direct current is transmitted to the first transformer T1 through the first switch Q1, at the same time, the current value of the first resonant circuit increases to store energy, at the same time, the seventh switch Q7 is turned on to rectify and filter the output voltage of the first transformer T1 through the second filter capacitor C11, so as to output a stable voltage to control the output current; when Q2, Q3 and Q5 are turned on, the resonant direct reverse voltage is transmitted to the first transformer T1 through the second switch Q2, at the same time, the reverse current value of the first resonant circuit increases to supply power to the first transformer T1, the eighth switch Q8 is turned on to rectify and filter the output voltage of the first transformer T1, so as to output a stable voltage to control the output current. Similarly, the working principles of the other two resonant circuits are consistent with this circuit.

[0031] With reference to Figure 2 ,Figure 2 The circuit schematic diagram of the second embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 of the present application is shown in FIG. 4. The difference between the second embodiment and the first embodiment is that the specific connection of the resonant circuit in the resonant cavity 200 and the inverter circuit and the transformer is different, and the rest of the circuit structure is the same or similar. In the second embodiment, the midpoint of the bridge arm composed of the first switch Q1 and the second switch Q2 in series is connected with the second capacitor C2 in the first resonant circuit, the midpoint of the bridge arm composed of the third switch Q3 and the fourth switch Q4 in series is connected with the second capacitor C5 in the second resonant circuit, the midpoint of the bridge arm composed of the fifth switch Q5 and the sixth switch Q6 in series is connected with the second capacitor C8 in the third resonant circuit, the third inductor L3, the third inductor L6 and the third inductor L9 are connected with each other to form a Y-type connection, and the third capacitor C3, the third capacitor C6 and the third capacitor C9 are connected with the same terminals of the primary windings of the first transformer T1, the second transformer T2 and the third transformer T3, respectively; while the second inductor L2, the second inductor L5 and the second inductor L8 are connected with the different terminals of the primary windings of the first transformer T1, the second transformer T2 and the third transformer T3, respectively.

[0032] Reference Figure 3 , Figure 3 The circuit schematic diagram of the third embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 of the present application is shown in FIG. 5. The difference between the third embodiment and the first embodiment is that the specific structure of the resonant circuit in the resonant cavity 200 is different, and the rest of the circuit structure is the same or similar. In the third embodiment, the resonant circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor and a third inductor, one end of the first inductor and the second inductor is connected with one end of the first capacitor and the second capacitor, the other end of the first inductor is connected with one end of the third inductor and connected to the midpoint of a bridge arm in the three-phase bridge switching circuit, the other end of the second inductor and the second capacitor is connected with the primary winding of a transformer, and the other end of the second inductor is connected with the other end of the third inductor, and the other end of the first capacitor in the three resonant circuits is connected with each other to form a Y-type connection.

[0033] As shown in the figure, specifically, the resonant cavity 200 includes a first resonant circuit, a second resonant circuit and a third resonant circuit, the first resonant circuit includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2 and a third inductor L3, the second resonant circuit includes a first capacitor C3, a second capacitor C4, a first inductor L4, a second inductor L5 and a third inductor L6, the third resonant circuit includes a first capacitor C5, a second capacitor C6, a first inductor L7, a second inductor L8 and a third inductor L9, in the embodiment shown in the figure, one end of the third inductor L3, the third inductor L6 and the third inductor L9 respectively corresponds to the connection of the midpoints of the three bridge arms of the three-phase bridge switching circuit 100, the other end of the third inductor L3, the third inductor L6 and the third inductor L9 respectively corresponds to the connection of the same name end of the primary winding of the first transformer T1, the second transformer T2 and the third transformer T3, the second capacitor C2, the second capacitor C4 and the second capacitor C6 respectively corresponds to the connection of the different name end of the primary winding of the first transformer T1, the second transformer T2 and the third transformer T3, the first capacitor C1, the first capacitor C3 and the first capacitor C5 are connected to each other to form a Y-type connection. The embodiment can also effectively improve the input and output voltage range of the converter 10, realize wide voltage range input and output, and when using switching frequency control, wide frequency control is not required to realize wide voltage range output, that is, the switching control frequency can be compressed to be narrow, and the efficiency is improved.

[0034] Referring to Figure 4 , Figure 4 The figure is a circuit schematic diagram of a fourth embodiment of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter 10 of the application, which is different from the first embodiment in that the specific structure of the resonant circuit in the resonant cavity 200 is different, and the rest of the circuit structure is the same or similar. In the embodiment, the resonant circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor and a third inductor, one end of the first inductor is connected to one end of the first capacitor and the third inductor, one end of the second inductor is connected to the other end of the third inductor and one end of the second capacitor, the other end of the first capacitor is connected to the midpoint of a bridge arm in the three-phase bridge switching circuit, the other end of the second inductor and the second capacitor is connected to the primary winding of a transformer, and the other end of the second inductor is connected to the other end of the first inductor.

[0035] As shown in the figure, specifically, the resonant cavity 200 includes a first resonant circuit, a second resonant circuit and a third resonant circuit, the first resonant circuit includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2 and a third inductor L3, the second resonant circuit includes a first capacitor C3, a second capacitor C4, a first inductor L4, a second inductor L5 and a third inductor L6, the third resonant circuit includes a first capacitor C5, a second capacitor C6, a first inductor L7, a second inductor L8 and a third inductor L9, in the embodiment shown in the figure, the first capacitor C1, the first capacitor C3 and the first capacitor C5 correspond to connecting the midpoints of the three bridge arms of the three-phase bridge circuit 100 respectively, the second capacitor C2, the second capacitor C4 and the second capacitor C6 correspond to connecting the same name ends of the primary windings of the first transformer T1, the second transformer T2 and the third transformer T3 respectively, the second inductor L2, the second inductor L5 and the second inductor L8 correspond to connecting the different name ends of the primary windings of the first transformer T1, the second transformer T2 and the third transformer T3 respectively, and the different name ends of the primary windings and the secondary windings of the first transformer T1, the second transformer T2 and the third transformer T3 are connected to each other to form a Y-type connection.

[0036] In summary, the three-phase interleaved wide-range high-efficiency isolated bidirectional converter of the present application uses three-phase interleaved technology in each circuit to reduce the ripple, and the equivalent circuits of the resonant circuits in the energy forward and reverse flow are multi-element resonant circuits, which realize soft switching and have small loss in forward and reverse operation, solving the problem that the traditional LLC resonant circuit cannot work with the same performance in reverse direction, that is, the three-phase interleaved wide-range high-efficiency isolated bidirectional converter of the present application can step up when the energy flows in the reverse direction, can effectively improve the input and output voltage range of the converter, realize wide voltage range output, and has the same gain when the energy flows in the forward and reverse directions, and the structure design of the resonant circuit of the present application can realize wide voltage range output without wide frequency control when using switching frequency control, that is, the switching control frequency can be compressed to be narrow, improving the efficiency.

[0037] The above only describes the preferred embodiments of the present application, but does not limit the present application in any form. Those skilled in the art can make various equivalent changes and improvements on the basis of the above embodiments, and any equivalent changes or modifications made within the scope of the claims shall fall within the protection scope of the present application.

Claims

1. A three-phase interleaved wide-range high-efficiency isolated bidirectional converter, characterized in that: The three-phase interleaved wide-range high-efficiency isolated bidirectional converter includes a three-phase bridge switching circuit, a resonant cavity, three transformers, and a three-phase bridge rectifier circuit. One side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit serve as the first connection side and the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter, respectively. The resonant cavity includes three resonant circuits, which are respectively connected between the midpoints of the three arms of the three-phase bridge switching circuit and the primary windings of the three transformers. The resonant circuit includes a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor, and a third inductor. One end of the first inductor is connected to one end of the second inductor, the first capacitor, and the third capacitor. The other ends of the first inductor and the first capacitor are respectively connected to one end of the third inductor and the second capacitor. One end of the third inductor is connected to the midpoint of one arm of a three-phase bridge switching circuit. The other ends of the second inductor and the third capacitor are respectively connected to the other ends of the third inductor and the second capacitor, and connected to the primary winding of a transformer. The ends of the second capacitor and the first capacitor in the three resonant circuits are respectively connected to each other to form a Y-type connection. The same-name ends of the secondary windings of the three transformers are respectively connected to the midpoints of the three arms of the three-phase bridge rectifier circuit. The opposite-name ends of the secondary windings of the three transformers are respectively connected to each other to form a Y-type connection.

2. The three-phase interleaved wide-range high-efficiency isolated bidirectional converter of claim 1, wherein: The three-phase bridge switching circuit includes six switching transistors. Every two switching transistors are connected in series to form a bridge arm. The three bridge arms are connected in parallel, and their two ends serve as the first connection side of the three-phase interleaved wide-range high-efficiency isolation bidirectional converter.

3. The three-phase interleaved wide-range high-efficiency isolated bidirectional converter of claim 1, wherein: The three-phase bridge rectifier circuit includes six switching transistors. Every two switching transistors are connected in series to form a bridge arm. The three bridge arms are connected in parallel, and their two ends serve as the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter.

4. The three-phase interleaved wide-range high-efficiency isolated bidirectional converter of claim 2 or 3, wherein: The switching transistor is selected from MOSFET, IGBT, GaN, or SiC power transistor.

5. The three-phase interleaved wide-range high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The three-phase interleaved wide-range high-efficiency isolated bidirectional converter also includes a first filter capacitor and a second filter capacitor. The two ends of the first filter capacitor are connected to the first connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter, and the two ends of the second filter capacitor are connected to the second connection side.

6. A three-phase interleaved wide-range high-efficiency isolated bidirectional converter, characterized in that: The three-phase interleaved wide-range high-efficiency isolated bidirectional converter includes a three-phase bridge switching circuit, a resonant cavity, three transformers, and a three-phase bridge rectifier circuit. One side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit serve as the first connection side and the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter, respectively. The resonant cavity includes three resonant circuits, which are respectively connected between the midpoints of the three arms of the three-phase bridge switching circuit and the primary windings of the three transformers. The resonant circuit includes a first capacitor, a second capacitor, a third capacitor, a first inductor, a second inductor, and a third inductor. One end of the first inductor is connected to one end of the second inductor, the first capacitor, and the third capacitor. The other ends of the first inductor and the first capacitor are respectively connected to one end of the third inductor and the second capacitor. One end of the second capacitor is connected to the midpoint of one arm of a three-phase bridge switching circuit. The other ends of the second inductor and the third capacitor are respectively connected to the other ends of the third inductor and the second capacitor, and connected to the primary winding of a transformer. The ends of the third inductors and the first inductors in the three resonant circuits are respectively connected to each other to form a Y-type connection. The same-name ends of the secondary windings of the three transformers are respectively connected to the midpoints of the three arms of the three-phase bridge rectifier circuit. The opposite-name ends of the secondary windings of the three transformers are respectively connected to each other to form a Y-type connection.

7. A three-phase interleaved wide-range high-efficiency isolated bidirectional converter, characterized in that: The three-phase interleaved wide-range high-efficiency isolated bidirectional converter includes a three-phase bridge switching circuit, a resonant cavity, three transformers, and a three-phase bridge rectifier circuit. One side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit serve as the first connection side and the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter, respectively. The resonant cavity includes three resonant circuits, which are respectively connected between the midpoints of the three arms of the three-phase bridge switching circuit and the primary windings of the three transformers. The resonant circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, and a third inductor. One end of each of the first and second inductors is connected to one end of the first and second capacitors, respectively. The other end of the first inductor is connected to one end of the third inductor and to the midpoint of one arm of a three-phase bridge rectifier circuit. The other ends of the second inductor and the second capacitor are connected to the primary winding of a transformer, and the other end of the second inductor is connected to the other end of the third inductor. The other ends of the first capacitors in the three resonant circuits are connected to each other to form a Y-connection. The same-named ends of the secondary windings of the three transformers are respectively connected to the midpoints of the three arms of the three-phase bridge rectifier circuit, and the opposite-named ends of the secondary windings of the three transformers are connected to each other to form a Y-connection.

8. A three-phase interleaved wide-range high-efficiency isolated bidirectional converter, characterized in that: The three-phase interleaved wide-range high-efficiency isolated bidirectional converter includes a three-phase bridge switching circuit, a resonant cavity, three transformers, and a three-phase bridge rectifier circuit. One side of the three-phase bridge switching circuit and the three-phase bridge rectifier circuit serve as the first connection side and the second connection side of the three-phase interleaved wide-range high-efficiency isolated bidirectional converter, respectively. The resonant cavity includes three resonant circuits, which are respectively connected between the midpoints of the three arms of the three-phase bridge switching circuit and the primary windings of the three transformers. The resonant circuit includes a first capacitor, a second capacitor, a first inductor, a second inductor, and a third inductor. One end of the first inductor is connected to one end of the first capacitor and one end of the third inductor. One end of the second inductor is connected to the other end of the third inductor and one end of the second capacitor. The other end of the first capacitor is connected to the midpoint of one arm of a three-phase bridge switching circuit. The other ends of the second inductor and the second capacitor are connected to the primary winding of a transformer, and the other end of the second inductor is connected to the other end of the first inductor. The same-named ends of the three transformer secondary windings are respectively connected to the midpoints of the three arms of the three-phase bridge rectifier circuit. The opposite-named ends of the three transformer primary and secondary windings are respectively connected to each other to form a Y-type connection.

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