Wide range high efficiency isolated bidirectional converter

Abstract

The application discloses a wide-range high-efficiency isolated bidirectional converter, which comprises an inverter circuit, a resonant circuit, a transformer and a rectifier circuit, wherein 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 with 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 with one end of the third inductor and the second capacitor, and serves as a first connecting end of the resonant circuit and is connected with the inverter circuit; the other end of the second inductor and the third capacitor is respectively connected with the other end of the third inductor and the second capacitor, and serves as a second connecting end of the resonant circuit and is connected with a primary winding of the transformer; a secondary winding of the transformer is connected with an input side of the rectifier circuit; an output side of the rectifier circuit and an input side of the inverter circuit respectively serve as a second external connecting end and a first external connecting end of the wide-range high-efficiency isolated bidirectional converter.

Description

TECHNICAL FIELD

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

[0002] The DC-DC bidirectional converter is a DC / DC converter capable of bidirectional energy transmission 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. In addition to realizing complete symmetry bidirectional, it must also be highly efficient.

[0003] In the traditional LLC resonant bidirectional converter, ZVS conduction of the primary side switch tube and ZCS conduction of the rectification side diode can be realized in both forward and reverse directions. However, when the energy flows in the reverse direction, the circuit characteristics are no longer LLC resonant characteristics but LC resonant characteristics, and the maximum voltage gain of LC resonance becomes 1, greatly reducing the voltage gain in the reverse direction, which cannot realize normal output in the reverse direction, thereby failing to realize complete symmetry bidirectional. In order to realize complete symmetry bidirectional energy flow, the industry adopts DAB or adds a one-stage topology circuit based on LLC to make up for the insufficient reverse gain of LLC, basically realizing complete symmetry bidirectional. However, both DAB hard switching and LLC two-stage topology architecture will cause low efficiency. Moreover, with the further development of the new energy industry, the voltage range of one end of the DC-DC bidirectional converter becomes wider and wider. In order to ensure the realization of wide-range forward and reverse complete symmetry bidirectional, high efficiency will become more difficult. A bidirectional DC-DC topology capable of realizing wide-range, forward and reverse gain complete symmetry and high efficiency will be the trend. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a wide-range high-efficiency isolated bidirectional converter capable of realizing wide-range, forward and reverse gain complete symmetry and high efficiency.

[0005] To solve the above technical problems, the application provides a wide-range high-efficiency isolated bidirectional converter, comprising an inverter circuit, a resonant circuit, a transformer and a rectifier circuit, wherein 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, and serves as a first connecting end of the resonant circuit, and is connected to the inverter 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 serves as a second connecting end of the resonant circuit, and is connected to a primary winding of the transformer, a secondary winding of the transformer is connected to an input side of the rectifier circuit, an output side of the rectifier circuit and an input side of the inverter circuit serve as a second external connecting end and a first external connecting end of the wide-range high-efficiency isolated bidirectional converter respectively.

[0006] Further technical solutions are as follows: the inverter circuit comprises four switch tubes, every two switch tubes are connected in series to form a bridge arm, and two bridge arms are connected in parallel, and two ends of the two bridge arms serve as the first external connecting end of the wide-range high-efficiency isolated bidirectional converter, and the first inductor and the first capacitor are connected to the middle points of the two bridge arms respectively.

[0007] Further technical solutions are as follows: the inverter circuit comprises two capacitors and two switch tubes, the two capacitors and the two switch tubes are connected in series to form a bridge arm, and two bridge arms are connected in parallel, and two ends of the two bridge arms serve as the first external connecting end of the wide-range high-efficiency isolated bidirectional converter, and the first inductor and the first capacitor are connected to the middle points of the two bridge arms respectively.

[0008] Further technical solutions are as follows: the inverter circuit comprises two switch tubes, the two switch tubes are connected in series to form a bridge arm, and the first inductor and the first capacitor are connected to the middle point of the bridge arm and the lowermost end / uppermost end of the bridge arm respectively.

[0009] Further technical solutions are as follows: the inverter circuit comprises two capacitors and four switch tubes, the two capacitors and the four switch tubes are connected in series to form a first bridge arm and a second bridge arm, and the first bridge arm and the second bridge arm are connected in parallel, and two ends of the first bridge arm and the second bridge arm serve as the first external connecting end of the wide-range high-efficiency isolated bidirectional converter, the middle point of the first bridge arm is connected to the middle point of the second bridge arm, and the first inductor and the first capacitor are connected to the upper bridge arm and the lower bridge arm of the second bridge arm respectively.

[0010] Further technical solutions are as follows: the inverter circuit comprises two capacitors, four switch tubes, two diodes and a tenth capacitor, the two capacitors and the four switch tubes are respectively connected in series to form a bridge arm, the two bridge arms are connected in parallel, and the two ends thereof are used as the first external connection end of the wide-range high-efficiency isolated bidirectional converter, the first inductor and the first capacitor are respectively connected to the middle points of the two bridge arms, the two diodes are connected in series and connected in parallel with the tenth capacitor, and are connected in parallel with the two switch tubes in the middle of the bridge arm formed by the four switch tubes in series, and the middle points of the bridge arms formed by the two capacitors are connected to the connection points between the two diodes connected in series.

[0011] Further technical solutions are as follows: the rectifier circuit comprises four switch tubes, every two switch tubes are connected in series to form a bridge arm, the two bridge arms are connected in parallel, and the two ends thereof are used as the second external connection end of the wide-range high-efficiency isolated bidirectional converter, and the same-named ends and the different-named ends of the secondary winding of the transformer are respectively connected to the middle points of the two bridge arms.

[0012] Further technical solutions are as follows: the 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 input side of the inverter circuit, and the two ends of the second filter capacitor are connected to the output side of the rectifier circuit.

[0013] To solve the above technical problems, the application further provides a wide-range high-efficiency isolated bidirectional converter, comprising an inverter circuit, a resonant circuit, a transformer and a rectifier circuit, wherein 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 first capacitor is used as the first connection end of the resonant circuit, and is connected to the inverter circuit, the other end of the second inductor is connected to the other end of the third inductor and the other end of the second capacitor is used as the second connection end of the resonant circuit, and is connected to the primary winding of the transformer, the secondary winding of the transformer is connected to the input side of the rectifier circuit, and the output side of the rectifier circuit and the input side of the inverter circuit are respectively used as the second external connection end and the first external connection end of the wide-range high-efficiency isolated bidirectional converter.

[0014] To solve the above technical problems, the application further provides a wide-range high-efficiency isolated bidirectional converter, comprising an inverter circuit, a resonant circuit, a transformer and a rectifier circuit, wherein 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 inductor is connected with the other end of the second inductor and the other end of the first capacitor as a first connecting end of the resonant circuit, the first connecting end is connected with the inverter circuit, the other end of the first inductor and the other end of the second capacitor as a second connecting end of the resonant circuit, the second connecting end is connected with a primary winding of the transformer, a secondary winding of the transformer is connected with an input side of the rectifier circuit, an output side of the rectifier circuit and an input side of the inverter circuit are respectively a second external connecting end and a first external connecting end of the wide-range high-efficiency isolated bidirectional converter.

[0015] Compared with the prior art, the resonant circuit in the wide-range high-efficiency isolated bidirectional converter of the application is a multi-element resonant circuit in the energy forward and reverse flow, and realizes soft switching in the forward and reverse operation, so the loss is small, and the problem that the traditional LLC resonant circuit cannot work in the reverse direction with the same performance is solved, that is, the wide-range high-efficiency isolated bidirectional converter of the application can step up when the energy flows in the reverse direction, can effectively improve the input and output voltage range of the converter, realizes wide voltage range output, and at the same time, the gain is the same when the energy flows in the forward and reverse directions, and the structure design of the resonant circuit of the application can realize wide voltage range output without wide frequency control when the switching frequency control is used, that is, the switching control frequency can be compressed to be narrow, and the efficiency is improved. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is a circuit schematic diagram of a first embodiment of the wide-range high-efficiency isolated bidirectional converter of the application.

[0017] Figure 2 is a simulation schematic diagram of the switching frequency and the output voltage when the wide-range high-efficiency isolated bidirectional converter of the application is in a step-up state.

[0018] Figure 3 is a simulation schematic diagram of the switching frequency and the output voltage when the wide-range high-efficiency isolated bidirectional converter of the application is in a step-down state.

[0019] Figure 4 is a circuit schematic diagram of a second embodiment of the wide-range high-efficiency isolated bidirectional converter of the application.

[0020] Figure 5 is a circuit schematic diagram of a third embodiment of the wide-range high-efficiency isolated bidirectional converter of the application.

[0021] Figure 6is a circuit schematic diagram of a fourth embodiment of the wide-range high-efficiency isolated bidirectional converter of the present application.

[0022] Figure 7 is a circuit schematic diagram of a fifth embodiment of the wide-range high-efficiency isolated bidirectional converter of the present application.

[0023] Figure 8 is a circuit schematic diagram of a sixth embodiment of the wide-range high-efficiency isolated bidirectional converter of the present application. DETAILED DESCRIPTION

[0024] In order to make the ordinary skilled in the art more clearly understand the purpose, technical solution and advantages of the present application, the present application is further described below in conjunction with the drawings and examples.

[0025] Reference Figure 1 , Figure 1 is a circuit schematic diagram of a first embodiment of the wide-range high-efficiency isolated bidirectional converter 10 of the present application. In the embodiment shown in the drawing, the wide-range high-efficiency isolated bidirectional converter 10 comprises an inverter circuit 11, a resonant circuit 12, a transformer T1 and a rectifier circuit 14, wherein the resonant circuit 12 comprises 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, one end of the first inductor L1 is connected to one end of the second inductor L2, the first capacitor C1 and the third capacitor C3, the other end of the first inductor L1 and the first capacitor C1 is connected to one end of the third inductor L3 and the second capacitor C2 respectively, and serves as a first connecting end of the resonant circuit 12, and is connected to the inverter circuit 11, the other end of the second inductor L2 and the third capacitor C3 is connected to the other end of the third inductor L3 and the second capacitor C2 respectively, and serves as a second connecting end of the resonant circuit 12, and is connected to a primary winding of the transformer T1, a secondary winding of the transformer T1 is connected to an input side of the rectifier circuit 14, an output side of the rectifier circuit 14 and an input side of the inverter circuit 11 respectively serve as a first external connecting end and a second external connecting end of the wide-range high-efficiency isolated bidirectional converter 10, so as to connect a load and a power supply. Preferably, the inductance of the first inductor L1 and the second inductor L2 is the same, and the capacitance of the first capacitor C1 and the third capacitor C3 is the same. In this embodiment, when the energy flows forward, the first external connecting end of the wide-range high-efficiency isolated bidirectional converter 10 serves as a direct current input end, and an external power supply can be connected thereto, and the second external connecting end thereof serves as a direct current output end, and an external load can be connected thereto; while when the energy flows reversely, the second external connecting end of the wide-range high-efficiency isolated bidirectional converter 10 serves as a direct current input end, and the first external connecting end thereof serves as a direct current output end.

[0026] In some embodiments, the inverter circuit 11 includes four switching tubes, i.e., a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, and a fourth switching tube Q4. Each two switching tubes are connected in series to form a bridge arm. Two bridge arms are connected in parallel, and the two ends thereof are used as the first external connection end of the wide-range high-efficiency isolated bidirectional converter 10. Specifically, in the embodiment, the midpoint of the bridge arm formed by the first switching tube Q1 and the second switching tube Q2 is connected to the first inductor L1 and the third inductor L3, and the midpoint of the bridge arm formed by the third switching tube Q3 and the fourth switching tube Q4 is connected to the first capacitor C1 and the second capacitor C2.

[0027] In the embodiment shown in the accompanying drawings, the rectifier circuit 14 includes four switching tubes, i.e., a fifth switching tube Q5, a sixth switching tube Q6, a seventh switching tube Q7, and an eighth switching tube Q8. Each two switching tubes are connected in series to form a bridge arm. Two bridge arms are connected in parallel, and the two ends thereof are used as the second external connection end of the wide-range high-efficiency isolated bidirectional converter 10. Specifically, the midpoint of the bridge arm formed by the fifth switching tube Q5 and the sixth switching tube Q6 and the midpoint of the bridge arm formed by the seventh switching tube Q7 and the eighth switching tube Q8 are respectively connected to the same end and the different end of the secondary winding of the transformer T1. Based on the design, when the energy flows forward, the rectifier circuit 14 can rectify the voltage waveform periodically output by the transformer T1 to generate the operating voltage required by the load. Preferably, the switching tubes are selected from MOS, IGBT, or other controllable power switching tubes to achieve better circuit performance. In the embodiment, a diode is also connected in parallel to the switching tube. If the switching tube is selected from a MOS tube, a diode is connected in parallel between the drain and the source of the MOS tube. If the switching tube is selected from an IGBT tube, a diode is connected in parallel between the emitter and the collector of the IGBT tube.

[0028] In the embodiment, the PFM mode is used to control the operation of the switching tube, i.e., a constant duty cycle is used to control the on and off time of the switching tube, and then the modulation square wave frequency mode is used to achieve adjustment. The switching frequency of the bidirectional converter in the prior art needs to be controlled in a wide range to achieve the voltage wide-range input and output, i.e., when the voltage is increased from 45V 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. The control range of the switching frequency of the wide-range high-efficiency isolated bidirectional converter of the present application is relatively small, as shown in Figure 2 Figure 2 ​The simulation curve chart of the switching frequency and the output voltage when the energy flows forward and the input is 45V, in which the first curve freq is the curve of the switching frequency, IS_Q is the DC input current waveform curve, IP_D1 is the current waveform curve of the fifth switch Q5 and the eighth switch Q8 in the DC output end, IP_D2 is the current waveform curve of the sixth switch Q6 and the seventh switch Q7 in the DC output end, and VOUT is the output voltage, which is 401.89V, and the switching frequency freq is 70KHZ; Figure 3 The simulation curve chart of the switching frequency and the output voltage when the energy flows backward and the input is 400V, in which the first curve freq is the curve of the switching frequency, IP_Q is the DC input current waveform curve, IS_D1 is the current waveform curve of the first switch Q1 and the fourth switch Q4 in the DC output end, IS_D2 is the current waveform curve of the third switch Q3 and the second switch Q2 in the DC output end, the output voltage is 43.262V, and the switching frequency freq is 120KHZ; in summary, under the condition of the same boost-buck gain, the switching frequency of the wide-range high-efficiency isolated bidirectional converter is smaller than that of the prior art bidirectional converter, and the wide voltage range output can be realized without wide frequency control, that is, the switching control frequency can be compressed and narrowed, and the efficiency is improved.

[0029] Further, the wide-range high-efficiency isolated bidirectional converter 10 further comprises a first filter capacitor C6 and a second filter capacitor C7, the first filter capacitor C6 is connected to the input side of the inverter circuit 11, and the second filter capacitor C7 is connected to the output side of the rectifier circuit 14.

[0030] Understandably, in the embodiment, when the energy flows forward, the wide-range voltage output of the 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 and the fourth switch Q4, and the two switches on each bridge arm are complementary on, and the circuit soft switching can be realized; when the energy flows backward, the resonant circuit 12 is a multi-element resonant circuit, and the same wide-range voltage output as when the energy flows forward can be realized by controlling the switching frequency of the fifth switch Q5, the sixth switch Q6, the seventh switch Q7 and the eighth switch Q8, and the two switches on each bridge arm are complementary on, and the circuit soft switching can also be realized.

[0031] Reference Figure 4 , Figure 4The circuit schematic of the second embodiment of the wide-range high-efficiency isolation bidirectional converter 10 of the present application is shown in the figure. The difference between the second embodiment and the first embodiment is the specific structure of the inverter circuit 11 and the specific connection of the resonant circuit 12 and the inverter circuit 11 and the transformer T1. The rest of the circuit structure is the same or similar. In the second embodiment, the inverter circuit 11 can also be composed of the fifth capacitor C5, the fourth capacitor C4, the first switch Q1 and the second switch Q2. The fifth capacitor C5 and the fourth capacitor C4 and the first switch Q1 and the second switch Q2 are respectively connected in series to form a bridge arm. The two bridge arms are connected in parallel, and the two ends thereof are used as the first external terminals of the wide-range high-efficiency isolation bidirectional converter 10. The midpoint of the bridge arm composed of the first switch Q1 and the second switch Q2 is connected with the first capacitor C1 and the second capacitor C2. The same end of the third capacitor C3 and the primary winding of the transformer T1 is connected. The midpoint of the bridge arm composed of the fifth capacitor C5 and the fourth capacitor C4 is connected with the first inductor L1 and the third inductor L3. The second inductor L2 is connected with the different end of the primary winding of the transformer T1. The second embodiment can also effectively improve the input and output voltage range of the converter 10 when the energy flows forward and backward, realize wide voltage range output, and at the same time retain good soft switching performance. The switching control frequency can be compressed and narrowed to improve the efficiency.

[0032] Reference Figure 5 , Figure 5The circuit schematic diagram of the third embodiment of the wide-range high-efficiency isolated bidirectional converter 10 of the present application is shown in the figure. The difference between the third embodiment and the second embodiment is that the specific structure of the resonant circuit 12 is different, and the rest of the circuit structure is the same or similar. In the third embodiment, the resonant circuit 12 includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, and a third inductor L3. One end of the first inductor L1 and the second inductor L2 is connected to one end of the first capacitor C1 and the second capacitor C2. The other end of the first inductor L1 is connected to one end of the third inductor L3, and the other end of the first capacitor C1 is used as the first connection end of the resonant circuit 12 and connected to the inverter circuit 11. The other end of the second inductor L2 is connected to the other end of the third inductor L3, and the other end of the second capacitor C2 is used as the second connection end of the resonant circuit 12 and connected to the primary winding of the transformer T1. In the third embodiment, the midpoint of the bridge arm formed by the series connection of the first switch Q1 and the second switch Q2 is connected to the first inductor L1 and the third inductor L3, and the midpoint of the bridge arm formed by the series connection of the fifth capacitor C5 and the fourth capacitor C4 is connected to the first capacitor C1. The other end of the third inductor L3 is connected to the second inductor L2 and the same end of the primary winding of the transformer T1, and the second capacitor C2 is connected to the different end of the primary winding of the transformer T1. The third embodiment can also effectively improve the input and output voltage range of the converter 10 when the energy flows in both directions, achieve wide voltage range output, while retaining good soft switching performance, and the switching control frequency can be compressed to be narrow, improving efficiency.

[0033] Referring to Figure 6 , Figure 6 The circuit schematic diagram of the fourth embodiment of the wide-range high-efficiency isolated bidirectional converter 10 of the present application is shown in the figure. The difference between the fourth embodiment and the first embodiment is that the specific circuit structure of the inverter circuit 11 is different, and the rest of the circuit structure is the same or similar. In the fourth embodiment, the inverter circuit 11 includes two switch tubes, i.e., the first switch Q1 and the second switch Q2, which are connected in series to form a bridge arm. The first inductor L1 and the first capacitor C1 are connected to the midpoint of the bridge arm and the lowermost end of the bridge arm, respectively. Understandably, in some other embodiments, the first capacitor C1 can be connected to the midpoint of the bridge arm, and the first inductor L1 can be connected to the uppermost end of the bridge arm.

[0034] Referring to Figure 7 , Figure 7A circuit schematic diagram of a fifth embodiment of the wide-range high-efficiency isolated bidirectional converter 10 of the present application is shown in FIG. 8. The fifth embodiment differs from the first embodiment in that the specific circuit structure of the inverter circuit 11 is different, and the rest of the circuit structure is the same or similar. In the fifth embodiment, the inverter circuit 11 includes two capacitors and four switching tubes, and two capacitors and four switching tubes are respectively connected in series to form a bridge arm. Specifically, the inverter circuit 11 includes an eighth capacitor C8 and a ninth capacitor C9, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, and a fourth switching tube Q4. The eighth capacitor C8 and the ninth capacitor C9 are connected in series to form a first bridge arm, and the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 are connected in series to form a second bridge arm. The two bridge arms are connected in parallel, and the two ends thereof serve as the first external connection end of the wide-range high-efficiency isolated bidirectional converter 10. The midpoint of the first bridge arm is connected to the midpoint of the second bridge arm. The first inductor L1 and the third inductor L3 are connected to the upper bridge arm of the second bridge arm, i.e., the connection point between the first switching tube Q1 and the third switching tube Q3. The first capacitor C1 and the second capacitor C2 are connected to the lower bridge arm of the second bridge arm, i.e., the connection point between the fourth switching tube Q4 and the second switching tube Q2.

[0035] Referring to Figure 8 , Figure 8As a circuit schematic view of the sixth embodiment of the wide-range high-efficiency isolated bidirectional converter 10 of the present application, the embodiment differs from the first embodiment in that the specific circuit structure of the inverter circuit 11 and the resonant circuit 12 is different, and the rest of the circuit structure is the same or similar. In the embodiment, the resonant circuit includes a first capacitor C1, a second capacitor C2, a first inductor L1, a second inductor L2, and a third inductor L3, one end of the first inductor L1 is connected to one end of the third inductor L3 and the first capacitor C1, one end of the second inductor L2 is connected to the other end of the third inductor L3 and one end of the second capacitor C2, the other end of the first inductor L1 is connected to the other end of the second inductor L2, and the other end of the first capacitor C1 is connected as the first connection end of the resonant circuit 12, connected to the inverter circuit 11, one end of the first inductor L1 and the second inductor L2 is connected to the opposite end of the primary winding of the transformer T1, and the other end of the second capacitor C2 is connected to the same end of the primary winding of the transformer T1; and the inverter circuit 11 includes two capacitors, four switching tubes, two diodes, and a tenth capacitor, two capacitors and four switching tubes are respectively connected in series to form a bridge arm, and the two ends of the two bridge arms are connected in parallel as the first external connection end of the wide-range high-efficiency isolated bidirectional converter 10. Specifically, the inverter circuit 11 includes an eighth capacitor C8 and a ninth capacitor C9, a first switching tube Q1, a second switching tube Q2, a third switching tube Q3, a fourth switching tube Q4, a first diode D1, a second diode D2, and a tenth capacitor C10, the midpoint of the bridge arm formed by the eighth capacitor C8 and the ninth capacitor C9 is connected to the first capacitor C1, and the midpoint of the bridge arm formed by the first switching tube Q1, the second switching tube Q2, the third switching tube Q3, and the fourth switching tube Q4 is connected to the first inductor L1 and the second inductor L2, the first diode D1 and the second diode D2 are connected in series and connected in parallel with the tenth capacitor C10, and the third switching tube Q3 and the fourth switching tube Q4, and the midpoint of the bridge arm formed by the eighth capacitor C8 and the ninth capacitor C9 is connected to the connection point between the first diode D1 and the second diode D2, that is, the midpoint of the bridge arm formed by the eighth capacitor C8 and the ninth capacitor C9 is connected to the anode of the first diode D1 and the cathode of the second diode D2. The embodiment can also effectively improve the input and output voltage range of the converter 10 when the energy flows in both directions, achieve wide voltage range output, while retaining good soft switching performance, and the switching control frequency can be compressed to be narrow, with high efficiency.

[0036] In summary, the equivalent circuit of the resonant circuit in the wide-range high-efficiency isolation bidirectional converter of the application is a multi-element resonant circuit when the energy flows forward and reversely, soft switching is realized when the energy flows forward and reversely, the loss is small, the problem that the traditional LLC resonant circuit cannot work reversely with the same performance is solved, that is, the wide-range high-efficiency isolation bidirectional converter of the application can step up when the energy flows reversely, can effectively improve the input and output voltage range of the converter, realizes wide voltage range output, at the same time, the gain is the same when the energy flows forward and reversely, and the structure design of the resonant circuit of the application can realize 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.

[0037] The above only describes the preferred embodiments of the application, and does not limit the 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 application.

Claims

1. A wide-range, high-efficiency isolated bidirectional converter, characterized in that: The wide-range, high-efficiency isolated bidirectional converter includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit. 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, serving as the first connection terminal of the resonant circuit, connecting to the inverter 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, serving as the second connection terminal of the resonant circuit, connecting to the primary winding of the transformer. The secondary winding of the transformer is connected to the input side of the rectifier circuit. The output side of the rectifier circuit and the input side of the inverter circuit serve as the second external terminal and the first external terminal of the wide-range, high-efficiency isolated bidirectional converter, respectively.

2. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The inverter circuit includes four switching transistors. Every two switching transistors are connected in series to form a bridge arm. The two bridge arms are connected in parallel, and their two ends serve as the first external terminals of a wide-range, high-efficiency isolated bidirectional converter. The first inductor and the first capacitor are respectively connected to the midpoint of the two bridge arms.

3. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The inverter circuit includes two capacitors and two switching transistors. The two capacitors and two switching transistors are connected in series to form a bridge arm. The two bridge arms are connected in parallel, and their two ends serve as the first external terminals of a wide-range, high-efficiency isolated bidirectional converter. The first inductor and the first capacitor are respectively connected to the midpoints of the two bridge arms.

4. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The inverter circuit includes two switching transistors connected in series to form a bridge arm. The first inductor and the first capacitor are respectively connected to the midpoint of the bridge arm and the bottom / top of the bridge arm.

5. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The inverter circuit includes two capacitors and four switching transistors. The two capacitors and four switching transistors are connected in series to form the first bridge arm and the second bridge arm, respectively. The first bridge arm and the second bridge arm are connected in parallel, and their two ends serve as the first external terminals of the wide-range high-efficiency isolation bidirectional converter. The midpoint of the first bridge arm is connected to the midpoint of the second bridge arm. The first inductor and the first capacitor are connected to the upper bridge arm and the lower bridge arm of the second bridge arm, respectively.

6. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The inverter circuit includes two capacitors, four switching transistors, two diodes, and a tenth capacitor. The two capacitors and four switching transistors are connected in series to form a bridge arm. The two bridge arms are connected in parallel, and their two ends serve as the first external terminals of a wide-range, high-efficiency isolated bidirectional converter. The first inductor and the first capacitor are respectively connected to the midpoints of the two bridge arms. The two diodes are connected in series and then in parallel with the tenth capacitor, and in parallel with the two switching transistors in the middle of the bridge arm formed by the four switching transistors connected in series. The midpoint of the bridge arm formed by the two capacitors is connected to the connection point between the two diodes connected in series.

7. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The rectifier circuit includes four switching transistors. Every two switching transistors are connected in series to form a bridge arm. The two bridge arms are connected in parallel, and their two ends serve as the second external terminals of a wide-range, high-efficiency, isolated bidirectional converter. The same-named terminals and different-named terminals of the transformer secondary winding are respectively connected to the midpoints of the two bridge arms.

8. The wide-range, high-efficiency isolated bidirectional converter as described in claim 1, characterized in that: The 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 input side of the inverter circuit, and the two ends of the second filter capacitor are connected to the output side of the rectifier circuit.

9. A wide-range, high-efficiency isolated bidirectional converter, characterized in that: The wide-range high-efficiency isolated bidirectional converter includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit. 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 together with the other end of the first capacitor, forms the first connection terminal of the resonant circuit, connecting to the inverter circuit. The other end of the second inductor is connected to the other end of the third inductor, and together with the other end of the second capacitor, forms the second connection terminal of the resonant circuit, connecting to the primary winding of the transformer. The secondary winding of the transformer is connected to the input side of the rectifier circuit. The output side of the rectifier circuit and the input side of the inverter circuit serve as the second external terminal and the first external terminal of the wide-range high-efficiency isolated bidirectional converter, respectively.

10. A wide-range, high-efficiency isolated bidirectional converter, characterized in that: The wide-range high-efficiency isolated bidirectional converter includes an inverter circuit, a resonant circuit, a transformer, and a rectifier circuit. 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 both the first and third inductors. 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 inductor is connected to the other end of the second inductor, and together with the other end of the first capacitor, forms the first connection terminal of the resonant circuit, connecting to the inverter circuit. The other end of the first inductor and the other end of the second capacitor form the second connection terminal of the resonant circuit, connecting to the primary winding of the transformer. The secondary winding of the transformer is connected to the input side of the rectifier circuit. The output side of the rectifier circuit and the input side of the inverter circuit serve as the second external terminal and the first external terminal of the wide-range high-efficiency isolated bidirectional converter, respectively.

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