Bidirectional large-transformation-ratio DC-to-DC isolation converter
By using a bidirectional high-ratio DC-DC isolated converter, and combining a buck-boost module and a dual active bridge DAB module, the shortcomings of existing bidirectional high-gain isolated DC-DC circuits are solved, achieving efficient voltage conversion and energy flow, and meeting the requirements for high voltage gain.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-08
- Publication Date
- 2026-04-10
AI Technical Summary
Existing technologies lack efficient bidirectional high-gain isolated DC-DC circuits, which cannot effectively boost the low DC voltage of renewable energy sources such as photovoltaic cells and fuel cells to higher DC voltages to meet grid-connected power generation or load requirements.
A bidirectional high-ratio DC-to-DC isolation converter is adopted, including a step-up/step-down module and a dual active bridge DAB module. The step-up/step-down module, composed of an H-bridge control module, bus capacitor, power inductor and disconnect switch, combined with a high-frequency isolation transformer and a fully controlled H-bridge inverter and rectifier module, realizes bidirectional energy flow and voltage conversion.
It achieves efficient voltage conversion under different input voltage conditions, reduces switching and conduction losses, optimizes transformer design, improves overall system efficiency, and meets the requirements of high voltage gain.
Smart Images
Figure CN121841118A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of energy technology, specifically to a bidirectional high-ratio DC-to-DC isolation converter. Background Technology
[0002] DC-DC power modules are power supplies that can be directly mounted on printed circuit boards. They can provide power to application-specific integrated circuits, digital signal processors, microprocessors, memories, field-programmable gate arrays, and other digital or analog loads. Due to their high reliability and ease of operation, they are widely used in rail transportation, medical, industrial control and other fields.
[0003] Currently, solar and wind power are considered the main foundation of the future world energy structure and an excellent way to solve the energy crisis. Developing clean, efficient, and renewable energy has become an important global issue. The power output of renewable energy sources such as photovoltaic cells and fuel cells is typically low DC voltage that varies over a wide range. Therefore, DC-DC converters with high voltage gain are needed to boost them to higher DC voltages to meet grid-connected power generation or load demands. In such new energy systems, bidirectional high-gain isolated DC-DC converters play a crucial role.
[0004] Therefore, how to provide bidirectional high-gain isolated DC-DC circuits is a technical issue that the industry urgently needs to solve. Summary of the Invention
[0005] In view of this, embodiments of the present invention provide a bidirectional high-ratio DC-DC isolated converter to solve the problem of the need for bidirectional high-gain isolated DC-DC circuits in the prior art.
[0006] According to a first aspect, embodiments of the present invention provide a bidirectional high-ratio DC-to-DC isolation converter, comprising: Buck-boost modules and dual active bridge (DAB) modules; The input terminal of the buck-boost module is connected to a DC power supply, and the output terminal of the buck-boost module is connected to the dual active bridge DAB module. The buck-boost module consists of an H-bridge control module, a bus capacitor, a power inductor, and an isolating switch. The input terminal of the H-bridge control module is connected to a DC power supply. The two ends of the power inductor are respectively connected to the midpoints of the two bridge arms of the H-bridge control module. The bus capacitor is connected to the endpoints of the two bridge arms of the H-bridge control module and is used to input a preset typical voltage. The two ends of the isolating switch are respectively connected to the positive power supply side of the two bridge arms of the H-bridge control module. The dual active bridge DAB module includes a first fully controlled H-bridge inverter module, a high-frequency isolation transformer, and a second fully controlled H-bridge rectifier module. The first fully controlled H-bridge inverter module and the second fully controlled H-bridge rectifier module are isolated by the high-frequency isolation transformer, and the input terminal of the first fully controlled H-bridge inverter module is connected to the output terminal of the buck-boost module.
[0007] In conjunction with the first aspect, in the first embodiment of the first aspect, the H-bridge control module includes: a first switch, a second switch, a third switch, and a fourth switch, wherein the first switch and the second switch constitute the first bridge arm of the H-bridge control unit, and the third switch and the fourth switch constitute the second bridge arm of the H-bridge control unit. The second ends of the first and third switching transistors serve as the positive power supply side, and the third ends of the second and fourth switching transistors serve as the negative power supply side. The third end of the first switching transistor is connected to the second end of the second switching transistor, and the third end of the third switching transistor is connected to the second end of the fourth switching transistor. One end of the bus capacitor is connected to the second end of the third switching transistor, and the other end of the bus capacitor is connected to the third end of the fourth switching transistor. One end of the power inductor is connected to the third end of the first switching transistor, and the other end of the power inductor is connected to the third end of the third switching transistor. One end of the disconnect switch is connected to the second end of the first switching transistor, and the other end of the disconnect switch is connected to the second end of the third switching transistor.
[0008] In conjunction with the first embodiment of the first aspect, in the second embodiment of the first aspect, the H-bridge control module further includes: A controller connected to each switching transistor.
[0009] In conjunction with the second embodiment of the first aspect, in the third embodiment of the first aspect, the switching transistor is a power MOSFET.
[0010] In conjunction with the second embodiment of the first aspect, in the fourth embodiment of the first aspect, the controller is a control chip or a control microcontroller.
[0011] In conjunction with the first aspect, in the fifth embodiment of the first aspect, the disconnecting switch is a relay, a power MOSFET, or an insulated gate transistor.
[0012] In conjunction with the first aspect, in the sixth embodiment of the first aspect, the first fully controlled H-bridge inverter module includes a first fully controlled H-bridge inverter unit, wherein the first fully controlled H-bridge inverter unit is an H-bridge inverter topology composed of four fully controlled power semiconductor devices.
[0013] In conjunction with the first aspect, in the seventh embodiment of the first aspect, the high-frequency isolation transformer is a single-phase dry-type iron-core high-frequency transformer.
[0014] In conjunction with the first aspect, in the eighth embodiment of the first aspect, the second fully controlled H-bridge rectifier module includes a second fully controlled H-bridge rectifier unit and a rectifier support capacitor, wherein the second fully controlled H-bridge rectifier unit and the rectifier support capacitor are connected in parallel, and the second fully controlled H-bridge rectifier unit is an H-bridge rectifier topology composed of four fully controlled power semiconductor devices.
[0015] In conjunction with the sixth or eighth embodiment of the first aspect, in the ninth embodiment of the first aspect, all fully controllable power semiconductor devices are integrated gate commutated thyristors, turn-off thyristors, power transistors, power MOSFETs, or insulated gate transistors.
[0016] The bidirectional high-ratio DC-DC isolation converter of this invention employs a four-switch dual-control mode buck-boost circuit to obtain the typical input voltage of the bus capacitor of the intermediate bus. This voltage is then passed through a dual active bridge DAB module to achieve isolated output. Since both the buck-boost module and the dual active bridge DAB module are bidirectional conversion circuits, cascading them also enables bidirectional energy flow. The input voltage of the bus capacitor of the intermediate bus is generally set near the typical input voltage value. Thus, when the typical input voltage value is applied, the four-switch buck-boost circuit can be bypassed by a switch, improving efficiency. Furthermore, since the input value of the dual active bridge DAB module is always near the typical voltage value under any input condition, the transformer design can be optimized, improving the overall system efficiency. Both the buck-boost module and the dual active bridge DAB module can achieve bidirectional energy flow and voltage conversion, thereby realizing bidirectional high-ratio voltage conversion. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] in: Figure 1 A schematic diagram of the bidirectional high-ratio DC-to-DC isolation converter provided by the present invention is shown. Figure 2 A schematic diagram showing the experimental results of the bidirectional high-ratio DC-to-DC isolation converter provided by the present invention is shown. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] DC-DC power modules are power supplies that can be directly mounted on printed circuit boards. They can provide power to application-specific integrated circuits, digital signal processors, microprocessors, memories, field-programmable gate arrays, and other digital or analog loads. Due to their high reliability and ease of operation, they are widely used in rail transportation, medical, industrial control and other fields.
[0021] Currently, the development and utilization of green and renewable energy sources such as solar, wind, and fuel cells have attracted much attention. Solar and wind energy are considered the main foundation of the future world energy structure and an excellent way to solve the energy crisis. Developing clean and efficient renewable energy has become an important global issue. However, the power output of renewable energy sources such as photovoltaic cells and fuel cells is usually low DC voltage that varies over a wide range. Therefore, DC converters with high voltage gain are needed to boost them to higher DC voltages to meet grid-connected power generation or load requirements.
[0022] Meanwhile, due to the intermittent nature of these natural resources, new energy power generation systems and energy storage devices such as supercapacitors and batteries are essential components. However, the basic unit output voltage of energy storage devices such as batteries is often relatively low (typically 12V-48V), so voltage isolation is required for safety reasons. Moreover, to meet grid connection requirements, their output DC bus usually needs to be above 400V, so the bidirectional DC-DC isolation circuit used in their interface needs to have high voltage gain. For example, in the rail transit field, the typical input value is 110V, but the input voltage range of its DC-DC module is 18Vdc-160Vdc. In addition, bidirectional high-gain isolation DC-DC converters also play an important role in applications such as electric vehicles, hybrid vehicles, uninterruptible power supply systems, lighting, and smart grids.
[0023] Therefore, how to provide bidirectional high-gain isolated DC-DC circuits is an important issue that the industry urgently needs to address.
[0024] To address the aforementioned issues, this specification provides a bidirectional, high-ratio DC-to-DC isolation converter. For example... Figure 1 and Figure 2 As shown, the converter may include: The system includes a buck-boost module and a dual active bridge (DAB) module. Specifically, the input of the buck-boost module is connected to a DC power supply, and the output of the buck-boost module is connected to the dual active bridge (DAB) module. The buck-boost module consists of an H-bridge control module, a bus capacitor C1, a power inductor L1, and an isolating switch K1. The input of the H-bridge control module is connected to a DC power supply. The two ends of the power inductor are connected to the midpoints of the two arms of the H-bridge control module, and the bus capacitor C1 is connected to the endpoints of the two arms of the H-bridge control module and used to input preset values. Typical input voltage value; the two ends of the isolating switch K1 are respectively connected to the positive power supply side of the two bridge arms of the H-bridge control module; the dual active bridge DAB module includes a first fully controlled H-bridge inverter module, a high-frequency isolation transformer, and a second fully controlled H-bridge rectifier module. The first fully controlled H-bridge inverter module and the second fully controlled H-bridge rectifier module are isolated by the high-frequency isolation transformer, and the input terminal of the first fully controlled H-bridge rectifier module is connected to the output terminal of the buck-boost module, that is, the input terminal of the first fully controlled H-bridge rectifier module is connected to the output terminal of the H-bridge control module.
[0025] More specifically, the H-bridge control module includes: a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4. The first switch S1 and the second switch S2 constitute the first bridge arm of the H-bridge control unit, and the third switch S3 and the fourth switch S4 constitute the second bridge arm of the H-bridge control unit. The power inductor L1 is located at the midpoint between the first and second bridge arms. The first switch S1, the second switch S2, and the power inductor L1 constitute the buck control module (BUCK) of the H-bridge control unit, and the third switch S3, the fourth switch S4, and the power inductor L1 constitute the boost control module (BOOST) of the H-bridge control unit.
[0026] The second terminals of the first switch S1 and the third switch S3 serve as the positive power supply side, and the third terminals of the second switch S2 and the fourth switch S4 serve as the negative power supply side. The third terminal of the first switch S1 is connected to the second terminal of the second switch S2, and the third terminal of the third switch S3 is connected to the second terminal of the fourth switch S4. One end of the bus capacitor C1 is connected to the second terminal of the third switch S3, and the other end of the bus capacitor C1 is connected to the third terminal of the fourth switch S4. One end of the power inductor L1 is connected to the third terminal of the first switch S1, and the other end of the power inductor L1 is connected to the third terminal of the third switch S3. One end of the isolating switch K1 is connected to the second terminal of the first switch S1, and the other end of the isolating switch K1 is connected to the second terminal of the third switch S3. The power inductor L1 can be used as a smoothing reactor in a buck-boost module.
[0027] In this embodiment, taking the energy flow from left to right as an example, the four-switch buck-boost module consists of the first to fourth switches S1-S4. It employs a simple two-mode control scheme. The voltage on the bus capacitor C1 of the intermediate bus is set to the typical value of the input voltage, i.e., the typical input voltage, such as 110Vdc for a power module used in a rail transit system. Therefore, when the input voltage is higher than this typical voltage (i.e., higher than 110Vdc), the third switch S3 is normally open, and the buck-boost module becomes a buck converter. Voltage regulation is achieved by adjusting the duty cycle of the first switch S1. When the input voltage is lower than this typical voltage, the first switch S1 is normally open, and the buck-boost module becomes a boost converter. Voltage regulation is achieved by adjusting the duty cycle of the third switch S3.
[0028] As can be seen, this bidirectional high-ratio DC-to-DC isolation converter has two control modes. It can operate in either buck or boost mode depending on the input voltage conditions. Compared to a simultaneous on / off configuration, this bidirectional high-ratio DC-to-DC isolation converter exhibits lower power inductor current ripple, resulting in lower conduction losses. Furthermore, regardless of whether it's in buck or boost mode, one bridge arm always remains in a constant on / off state, with only one switching transistor performing hard switching, thus further reducing switching losses.
[0029] When the input voltage is typical, all four switching transistors, namely the first to fourth switching transistors S1-S4, are open. At this time, the isolating switch K1 is closed. Preferably, the isolating switch K1 is composed of back-to-back bidirectional switching transistors such as MOSFETs, IGBTs, or relays. This way, no switching devices are involved in the operation of the front-end, reducing losses and improving the efficiency of the entire system.
[0030] In this embodiment, the buck-boost module also includes a controller connected to each switching transistor, and each controller can be responsible for controlling the switching state of the corresponding switching transistor.
[0031] In this embodiment, the controller, or control unit, can be an FPGA control chip or a microcontroller or other control device. The controller is used to control the closing or opening of the corresponding connected switching transistors S1-S4. After receiving the user's control command, the controller can control the closing or opening of each switching transistor in the buck-boost module to realize the bidirectional flow of energy on both sides. The entire circuit has a simple structure and low cost.
[0032] The dual active bridge DAB module after the BUCK-BOOST module adopts an isolated conversion scheme. The high-frequency isolation transformer can be optimized under typical input voltage, which greatly helps to improve system efficiency.
[0033] Taking a dual active bridge DAB module isolated by a first fully controlled H-bridge inverter module and a second fully controlled H-bridge rectifier module as an example, the first fully controlled H-bridge inverter module includes a first fully controlled H-bridge inverter unit, which is an H-bridge inverter topology composed of four fully controlled power semiconductor devices. The second fully controlled H-bridge rectifier module includes a second fully controlled H-bridge rectifier unit and a rectifier support capacitor, which are connected in parallel. The second fully controlled H-bridge rectifier unit is an H-bridge rectifier topology composed of four fully controlled power semiconductor devices.
[0034] Preferably, the high-frequency isolation transformer is a single-phase dry-type iron-core high-frequency transformer, which reduces the high-frequency voltage by 1 / n times. The input terminal of the high-frequency isolation transformer is connected to the output terminal of the first fully controlled H-bridge rectifier module, and the output terminal of the high-frequency isolation transformer is connected to the second fully controlled H-bridge rectifier unit. The equivalent leakage reactance of the high-frequency isolation transformer is Lr. The second fully controlled H-bridge rectifier unit rectifies the single-phase high-frequency AC power input to the high-frequency isolation transformer into a low-voltage DC power with ripple. The DC output terminal of the second fully controlled H-bridge rectifier unit is connected in series with a filter inductor L0 and in parallel with a rectifier support capacitor C0 to achieve DC ripple voltage suppression.
[0035] It should be noted that the first fully controlled H-bridge rectifier module and the second fully controlled H-bridge rectifier unit in the dual active bridge DAB module can use a hard-switching full-bridge, a phase-shifting full-bridge, or an LLC to achieve the function of isolation transformer.
[0036] In this embodiment, the fully controllable power semiconductor device described above can be selected from components such as GTO, GTR, IGBT, MOSFET, SiC-IGBT, and SiC-MOSFET.
[0037] The bidirectional high-ratio DC-DC isolation converter of this invention employs a four-switch dual-control mode buck-boost circuit to obtain the typical input voltage of the bus capacitor of the intermediate bus. This voltage is then passed through a dual active bridge DAB module to achieve isolated output. Since both the buck-boost module and the dual active bridge DAB module are bidirectional conversion circuits, cascading them also enables bidirectional energy flow. The input voltage of the bus capacitor of the intermediate bus is generally set near the typical input voltage value. Thus, when the typical input voltage value is applied, the four-switch buck-boost circuit can be bypassed by a switch, improving efficiency. Furthermore, since the input value of the dual active bridge DAB module is always near the typical voltage value under any input condition, the transformer design can be optimized, improving the overall system efficiency. Both the buck-boost module and the dual active bridge DAB module can achieve bidirectional energy flow and voltage conversion, thereby realizing bidirectional high-ratio voltage conversion.
[0038] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods described in the various embodiments or some parts of the embodiments.
[0039] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A bidirectional high-ratio isolated dc-dc converter, characterized by, The utility model relates to a kind of DC-DC converter, including: Boosting and bucking module and double active bridge DAB module; The input end of the boosting and bucking module is connected to DC power supply, and the output end of the boosting and bucking module is connected to the double active bridge DAB module, the boosting and bucking module is composed of H bridge control module, bus capacitor, power inductance and isolating switch, the input end of the H bridge control module is connected to DC power supply, the two ends of the power inductance are connected with the midpoint of the two bridge arms of the H bridge control module respectively, the bus capacitor is connected with the two bridge arm end points of the H bridge control module and is used to input preset typical voltage, the two ends of the isolating switch are connected with the power supply positive side of the two bridge arms of the H bridge control module respectively; The double active bridge DAB module includes first full-control H bridge inverter module, high-frequency isolation transformer and second full-control H bridge rectifier module, the first full-control H bridge inverter module is isolated with the second full-control H bridge rectifier module through the high-frequency isolation transformer, and the input end of the first full-control H bridge inverter module is connected with the output end of the boosting and bucking module.
2. The dual active bridge (DAB) module of claim 1, wherein, The H bridge control module includes first switch tube, second switch tube, third switch tube and fourth switch tube, the first switch tube and the second switch tube constitute the first bridge arm of the H bridge control unit, and the third switch tube and the fourth switch tube constitute the second bridge arm of the H bridge control unit; The second end of the first switch tube and the third switch tube is used as power supply positive side, the third end of the second switch tube and the fourth switch tube is used as power supply negative side, the third end of the first switch tube is connected with the second end of the second switch tube, the third end of the third switch tube is connected with the second end of the fourth switch tube, one end of the bus capacitor is connected with the second end of the third switch tube, the other end of the bus capacitor is connected with the third end of the fourth switch tube, one end of the power inductance is connected with the third end of the first switch tube, the other end of the power inductance is connected with the third end of the third switch tube, one end of the isolating switch is connected with the second end of the first switch tube, and the other end of the isolating switch is connected with the second end of the third switch tube.
3. The bidirectional Dc-Dc isolated converter with high voltage gain according to claim 2, characterized in that, The H bridge control module further includes: Controller connected with each switch tube.
4. The bidirectional Dc-Dc isolated converter with high voltage gain according to claim 3, characterized in that, The switch tube is power field effect transistor.
5. The bidirectional Dc-Dc isolated converter with high voltage gain according to claim 3, characterized in that, The controller is control chip or control single-chip microcomputer.
6. The bidirectional dc-dc isolated converter with high voltage gain according to claim 1, wherein, The isolating switch is relay, power field effect transistor or insulated gate transistor.
7. The bidirectional dc-dc isolated converter with high voltage gain according to claim 1, wherein, The first full-control H bridge inverter module includes first full-control H bridge inverter unit, and the first full-control H bridge inverter unit is H bridge inverter topology composed of four full-control power semiconductor devices.
8. The bidirectional dc-dc isolated converter with high voltage gain according to claim 1, wherein, The high-frequency isolation transformer is single-phase dry-type core high-frequency transformer.
9. The bidirectional dc-dc isolated converter with high voltage gain according to claim 1, wherein, The second full-control H bridge rectifier module includes second full-control H bridge rectifier unit and rectification support capacitor, and the second full-control H bridge rectifier unit and the rectification support capacitor are arranged in parallel, and the second full-control H bridge rectifier unit is H bridge rectification topology composed of four full-control power semiconductor devices.
10. The bidirectional Dc-Dc isolated converter with high voltage gain according to claim 7 or 9, characterized in that, All full-control power semiconductor devices are integrated gate-commutated thyristor, gate-cutoff thyristor, power transistor, power field effect transistor or insulated gate transistor.