Dc-dc power converter and method of controlling the same

Abstract

The embodiment of the application discloses a kind of DC-DC power converter and its control method, it is related to new energy automobile vehicle-mounted product technical field, DC-DC power converter includes high-voltage side filter device, high-voltage side H bridge device, isolation device, full-bridge rectifier device, double series inductance device and low-voltage side filter device, isolation device includes transformer magnetic core, double series inductance device includes first inductor, second inductor and double inductance magnetic core, first inductor and second inductor are wound in double inductance magnetic core in series, transformer magnetic core and double inductance magnetic core are integrated magnetic core with common magnetic flux loop.By adopting double inductance series architecture, the core bearing pressure of single output inductance is shared, combined with low-voltage side full-bridge rectifier circuit, the switching tube electric stress is halved, and the magnetic field in local magnetic circuit is offset by using integrated magnetic core, the heat quantity of core body is reduced, the conversion efficiency and output voltage range of DC-DC power converter are improved.

Description

Technical Field

[0001] This invention relates to the field of on-board products technology for new energy vehicles, and in particular to a DC-DC power converter and its control method. Background Technology

[0002] With the continuous development of new energy vehicle technology, lightweighting, miniaturization, and high power density of automotive components have become mainstream technological trends. For automotive DC-DC products, industry engineers not only need to research more efficient DC-DC topologies, but also continuously explore product process routes to reduce the size of automotive DC-DC products, reduce heat generation and losses, and improve conversion efficiency.

[0003] In existing isolated phase-shifted full-bridge DC-DC power converter technology, a separate transformer with an intermediate shaft head is often used, matched with a full-wave rectifier circuit and a separate single output inductor. That is, the transformer and inductor of the phase-shifted full-bridge topology are separate, which not only has a large size, but also a low upper limit of output power. Especially when the vehicle battery increases from 12V to 27V or 48V, the DC-DC output-side switching transistors need to withstand higher voltage stress, which cannot well meet the future requirements of higher power and higher voltage battery loads. Summary of the Invention

[0004] The purpose of this invention is to propose a DC-DC power converter and its control method, which aims to solve the problem that existing DC-DC power converters cannot meet the requirements of higher voltage and higher power battery loads.

[0005] In a first aspect, this embodiment provides a DC-DC power converter, comprising: High-voltage side filter device, high-voltage side H-bridge device, isolation device, full-bridge rectifier device, dual series inductor device and low-voltage side filter device; The isolation device includes a DC blocking capacitor and a transformer. The transformer includes a high-voltage coil, a low-voltage coil, and a transformer core. Both the high-voltage coil and the low-voltage coil are wound around the transformer core. The dual-series inductor device includes a first inductor coil, a second inductor coil, and a dual-inductor core, wherein the first inductor coil and the second inductor coil are wound in series around the dual-inductor core; The electrical signal of the DC-DC power converter flows sequentially through the high-voltage side filter, the high-voltage side H-bridge device, the isolation device, the full-bridge rectifier, the dual series inductor device, and the low-voltage side filter. One end of the first inductor is electrically connected to the positive output port of the full-bridge rectifier, and the other end of the first inductor is electrically connected to the second inductor.

[0006] In one optional implementation of this application, the transformer core and the dual-inductor core are an integral core with a shared magnetic flux loop.

[0007] In one optional implementation of this application, the integrated magnetic core includes a first magnetic chassis and a second magnetic chassis, as well as a transformer magnetic column, a common magnetic wall, a first inductor magnetic column and a second inductor magnetic column located between the first magnetic chassis and the second magnetic chassis; The transformer core includes a first magnetic base, a second magnetic base, a transformer magnetic column, and a common magnetic wall. The dual-inductor core includes a first magnetic base, a second magnetic base, a first inductor magnetic column, a second inductor magnetic column, and a common magnetic wall. The high-voltage coil and the low-voltage coil are both wound on the transformer magnetic column. The first inductor coil is wound on the first inductor magnetic column, and the second inductor coil is wound on the second inductor magnetic column. The shared magnetic flux loop includes the magnetic path formed in the shared magnetic wall.

[0008] In one optional implementation of this application, both the first inductor post and the second inductor post have magnetic gaps in the magnetic flux loop, and the magnetic gaps are used to adjust the inductance of the first inductor coil and the second inductor coil.

[0009] In one optional implementation of this application, both the transformer magnetic column and the shared magnetic wall are closed magnets, and the closed magnets do not have magnetic gaps in the magnetic flux loop.

[0010] In one optional implementation of this application, in the same direction perpendicular to the cross-section of the first inductor or the second inductor, the current flow direction of the first inductor coil around the first inductor is opposite to the current flow direction of the second inductor coil around the second inductor.

[0011] In one optional implementation of this application embodiment, the high-voltage side filter device includes a first capacitor; The high-voltage side H-bridge device includes a first power semiconductor, a second power semiconductor, a third power semiconductor, and a fourth power semiconductor. The first power semiconductor and the second power semiconductor constitute a first bridge arm, and the third power semiconductor and the fourth power semiconductor constitute a second bridge arm. The full-bridge rectifier includes a fifth power semiconductor, a sixth power semiconductor, a seventh power semiconductor, and an eighth power semiconductor. The fifth power semiconductor and the seventh power semiconductor constitute the third bridge arm, and the sixth power semiconductor and the eighth power semiconductor constitute the fourth bridge arm. The low-voltage side filter device includes a second capacitor; One end of the high-voltage coil is electrically connected between the second power semiconductor and the fourth power semiconductor, and the other end of the high-voltage coil is electrically connected between the first power semiconductor and the third power semiconductor through the DC blocking capacitor; one end of the low-voltage coil is electrically connected between the fifth power semiconductor and the seventh power semiconductor, and the other end of the low-voltage coil is electrically connected between the sixth power semiconductor and the eighth power semiconductor; The positive output port of the full-bridge rectifier is located on the parallel connection line of the fifth power semiconductor and the sixth power semiconductor.

[0012] Secondly, this embodiment provides a control method for a DC-DC power converter applied to the first aspect described above, the method comprising: If the DC-DC power converter needs to be in the first state, the second and third power semiconductors are turned on simultaneously, and the first and fourth power semiconductors are turned off. The fifth and eighth power semiconductors are turned on simultaneously, and the sixth and seventh power semiconductors are turned off simultaneously, forming the first rectifier branch on the low-voltage side. The current loop of the first rectifier branch is as follows: low-voltage coil, the fifth power semiconductor, the first inductor coil, the second inductor coil, the low-voltage side filter device, the eighth power semiconductor, and back to the low-voltage coil; If the DC-DC power converter needs to be in the second state, the first power semiconductor and the fourth power semiconductor are controlled to be turned on simultaneously, and the second power semiconductor and the third power semiconductor are turned off, and the sixth power semiconductor and the seventh power semiconductor are controlled to be turned on simultaneously, and the fifth power semiconductor and the eighth power semiconductor are turned off simultaneously, forming the second rectifier branch on the low-voltage side; The current loop of the second rectifier branch is as follows: the low-voltage coil, the sixth power semiconductor, the first inductor, the second inductor, the low-voltage side filter, the seventh power semiconductor, and back to the low-voltage coil.

[0013] In one optional implementation of this application, the pulse signal control logic of the first power semiconductor and the third power semiconductor are opposite, and a first dead time is provided; the pulse signal control logic of the second power semiconductor and the fourth power semiconductor are opposite, and a second dead time is provided. The pulse signal control logic of the first power semiconductor and the second power semiconductor has a phase difference of 0 to 180 degrees to control the direction of current in the low-voltage coil.

[0014] In one optional implementation of this application embodiment, the method further includes: If the DC-DC power converter needs to be in the third state, the first power semiconductor and the second power semiconductor are controlled to be turned on simultaneously, and the third power semiconductor and the fourth power semiconductor are turned off, and the fifth power semiconductor, the sixth power semiconductor, the seventh power semiconductor and the eighth power semiconductor are controlled to be turned on simultaneously to form a freewheeling circuit on the low-voltage side. If the DC-DC power converter needs to be in the fourth state, then the third power semiconductor and the fourth power semiconductor are controlled to be turned on simultaneously, and the first power semiconductor and the second power semiconductor are turned off, and the fifth power semiconductor, the sixth power semiconductor, the seventh power semiconductor and the eighth power semiconductor are controlled to be turned on simultaneously to form a freewheeling circuit on the low-voltage side; The current loop of the freewheeling circuit is as follows: the first inductor, the second inductor, the low-voltage side filter, the seventh and eighth power semiconductors, the fifth and sixth power semiconductors, and back to the first inductor. In the first and second states, the dual series inductor is in an energy storage state with an increasing current slope. In the third and fourth states, the dual series inductor is in a discharge state with a decreasing current slope.

[0015] The embodiments of the present invention have the following beneficial effects: This invention adopts a dual-inductor series architecture, which distributes the inductance of a single output inductor to two inductors connected in series. The effective magnetic flux cross-section of the magnetic core corresponding to each inductor is halved, and the heat generated by the magnetic core body is distributed to the two inductors, which is more conducive to heat dissipation. This reduces the magnetic core load pressure of a single output inductor and can meet the requirements of higher output power levels. Meanwhile, the low-voltage side is matched with a full-bridge rectifier, which is different from the full-wave rectifier circuit with an intermediate shaft transformer on the low-voltage side. This halves the electrical stress on the low-voltage side switching transistors. With the same voltage rating of the low-voltage side switching transistors, a higher low-voltage voltage can be output, thus expanding the output voltage range of the DC-DC power converter. Furthermore, by adopting a deep integration of the dual-output inductor core and the transformer core, the magnetic field generated by the differential mode current of the dual inductors and the magnetic field generated by the high-voltage coil of the transformer cancel each other out in the shared magnetic wall, reducing the average magnetic flux density of the core body and reducing the heat generation of the core body from the source. This not only reduces the size and weight of the core body and the cost of raw materials, but also improves the conversion efficiency of the DC-DC power converter. Attached Figure Description

[0016] 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.

[0017] in: Figure 1 This is a block diagram of a DC-DC power converter in one embodiment; Figure 2 This is a schematic diagram of the structure of an integral magnetic core in one embodiment; Figure 3 This is a schematic diagram of the transformer structure in one embodiment; Figure 4 This is a schematic diagram of the circuit topology of a DC-DC power converter in another embodiment. Figure 5 This is a schematic diagram of the current loop in the first state of one embodiment; Figure 6 This is a schematic diagram of the current loop in the second state of one embodiment; Figure 7 This is a schematic diagram of the current loop in the third state of one embodiment; Figure 8 This is a schematic diagram of the current loop in the fourth state of one embodiment; Figure 9 This is a simulation diagram of the control method in one embodiment; Figure 10 This is another simulation diagram of the control method in one embodiment.

[0018] Markings: 1. Transformer core; 2. Dual-inductor core; 3. First magnetic base; 4. Second magnetic base; 5. Transformer column; 6. Shared magnetic wall; 7. First inductor column; 8. Second inductor column; 9. High-voltage coil; 10. Low-voltage coil; 11. First inductor coil; 12. Second inductor coil; 13. Magnetic gap. Detailed Implementation

[0019] 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, and 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] With the continuous development of new energy vehicle technology, lightweighting, miniaturization, and high power density of automotive components have become mainstream technological trends. For automotive DC-DC products, industry engineers not only need to research more efficient DC-DC topologies, but also continuously explore product process routes to reduce the size of automotive DC-DC products, reduce heat generation and losses, and improve conversion efficiency.

[0021] In existing isolated phase-shifted full-bridge DC-DC power converter technology, a separate transformer with an intermediate shaft head is often used, matched with a full-wave rectifier circuit and a separate single output inductor. That is, the transformer and inductor of the phase-shifted full-bridge topology are separate, which not only has a large size, but also a low upper limit of output power. Especially when the vehicle battery increases from 12V to 27V or 48V, the DC-DC output-side switching transistors need to withstand higher voltage stress, which cannot well meet the future battery load requirements of higher power and higher voltage.

[0022] Therefore, in order to meet the growing demand for low-voltage loads, this application proposes a DC-DC power converter and its control method, wherein the low-voltage side is matched with a full-bridge rectifier and the low-voltage side of the transformer does not have an intermediate shaft head, which can be applied to low-voltage load systems such as isolated DC-DC converters in new energy vehicles that require greater output power and higher voltage.

[0023] Next, the DC-DC power converter provided in the embodiments of this application will be further described. For example... Figure 1 The diagram shown is a structural block diagram of the DC-DC power converter provided in this embodiment, which specifically includes the following contents.

[0024] A DC-DC power converter includes a high-voltage side filter, a high-voltage side H-bridge device, an isolation device, a full-bridge rectifier, a dual-series inductor device, and a low-voltage side filter. The isolation device includes a DC blocking capacitor and a transformer. The transformer includes a high-voltage coil 9, a low-voltage coil 10, and a transformer core 1. Both the high-voltage coil 9 and the low-voltage coil 10 are wound around the transformer core 1. The dual-series inductor device includes a first inductor coil 11, a second inductor coil 12, and a dual-inductor core 2. The first inductor coil 11 and the second inductor coil 12 are wound in series around the dual-inductor core 2. The electrical signal of the DC-DC power converter flows sequentially through the high-voltage side filter, the high-voltage side H-bridge device, the isolation device, the full-bridge rectifier, the dual-series inductor device, and the low-voltage side filter. One end of the first inductor coil 11 is electrically connected to the positive output port of the full-bridge rectifier, and the other end of the first inductor coil 11 is electrically connected to the second inductor coil 12.

[0025] The high-voltage side filter device filters the DC input from the high-voltage side, removing high-frequency ripple and providing a stable DC input for subsequent circuits. The high-voltage side H-bridge device performs DC-to-AC inverter conversion, using high-frequency switching of the switching transistors to convert DC into high-frequency AC to drive the isolation device. The DC blocking capacitor in the isolation device isolates the DC component, preventing DC bias from saturating the transformer core 1. Both the high-voltage coil 9 and the low-voltage coil 10 are wound around the transformer core 1, achieving energy transfer and electrical isolation between the high-voltage and low-voltage sides through electromagnetic coupling.

[0026] The full-bridge rectifier is used to rectify the AC output from the low-voltage side of the transformer into DC. The first inductor coil 11 and the second inductor coil 12 are used to filter out the ripple current after rectification, making the output current smoother. The low-voltage side filter is used to further filter the output DC to provide a stable DC output to the load.

[0027] The electrical signal can be current or voltage. The DC power on the high-voltage side is first filtered by the high-voltage side filter device, then converted into high-frequency AC power by the high-voltage side H-bridge device, and then stepped down and isolated by the isolation device. The output low-voltage AC power is rectified into DC power by the full-bridge rectifier device, and then filtered by the dual series inductor device and the low-voltage side filter device before being output to the load.

[0028] The forward current after rectification by the full-bridge rectifier flows sequentially through the first inductor coil 11 and the second inductor coil 12. The two inductors are connected in series and jointly perform the function of the output inductor. The effective magnetic flux cross-section of the magnetic core corresponding to each inductor is halved, and the heat generated by the magnetic core body is distributed between the two inductors, which is more conducive to heat dissipation.

[0029] To illustrate, for example, when a circuit system requires a 2uH output inductance for a phase-shifted full-bridge circuit, if a single inductor is used as the output inductor, the effective magnetic flux cross-section of the core corresponding to the single output inductor is relatively large, resulting in a concentrated heat generation in the core body, which is not conducive to heat transfer and increases the cost of the heat dissipation device. However, if two 1uH inductors are set and connected in series, the effective magnetic flux cross-section of the core corresponding to the two series-connected inductors will be halved, and the heat generation of the core body will be distributed between the two inductors, which is more conducive to heat dissipation.

[0030] It should be noted that the transformer in this embodiment does not have an intermediate shaft end on the low-voltage side, and the low-voltage side is matched with a full-bridge rectifier. Since the switching transistor in the full-bridge rectifier only bears half of the output voltage when it is turned on, the electrical stress of the low-voltage side switching transistor is halved. When using the same voltage rating low-voltage side switching transistor, a higher low-voltage voltage can be output, expanding the output voltage range of the DC-DC power converter, for example, from a 12V low-voltage platform to a 27V low-voltage platform.

[0031] By adopting the above method, the magnetic core bearing pressure of a single output inductor is distributed through a dual-series inductor architecture, which can meet the requirements of higher output power levels. At the same time, the transformer low-voltage side does not have an intermediate shaft head and is matched with a full-bridge rectifier, which halves the electrical stress of the low-voltage side switching tube and expands the output voltage range.

[0032] In another embodiment of this application, the transformer core 1 and the dual-inductor core 2 are an integral core with a shared magnetic flux loop.

[0033] In this context, the integrated magnetic core refers to the transformer core 1 and the dual-inductor core 2 being physically connected as a single unit, rather than being separate cores. Specifically, the integrated magnetic core is formed by two integrally molded core blocks that abut against each other, forming a shared magnetic wall 6. The transformer core 1 and the dual-inductor core 2 share the magnetic flux loop within this shared magnetic wall 6. By adopting an integrated magnetic core, a deep integration of the dual-output inductor core and the transformer core 1 is achieved. This not only reduces the size and weight of the core body and lowers raw material costs, but also ensures that the magnetic field generated by the differential-mode current of the dual inductors cancels out the magnetic field generated by the transformer's high-voltage coil 9 within the shared magnetic wall 6, forming a cancellation zone. This reduces heat generation at the source and improves the conversion efficiency of the DC-DC power converter.

[0034] For ease of understanding, such as Figure 2 As shown, the integrated magnetic core includes two magnetic core blocks with magnetic bases. After the two magnetic core blocks abut against each other, the transformer magnetic core 1 and the dual-inductance magnetic core 2 share the magnetic wall of the abutment part.

[0035] By adopting the above method, the transformer core 1 and the dual-inductor core 2 are designed as an integrated core, so that the magnetic fields in the local magnetic circuit cancel each other out, reducing the average magnetic flux density of the core body, reducing the heat generation of the core body from the source, and improving the conversion efficiency.

[0036] In another embodiment of this application, such as Figure 3 As shown, the integrated magnetic core includes a first magnetic chassis 3 and a second magnetic chassis 4, as well as a transformer magnetic column 5, a common magnetic wall 6, a first inductor magnetic column 7 and a second inductor magnetic column 8 located between the first magnetic chassis 3 and the second magnetic chassis 4; the transformer magnetic core 1 includes a first magnetic chassis 3, a second magnetic chassis 4, a transformer magnetic column 5 and a common magnetic wall 6, and the dual inductor magnetic core 2 includes a first magnetic chassis 3, a second magnetic chassis 4, a first inductor magnetic column 7, a second inductor magnetic column 8 and a common magnetic wall 6, a high-voltage coil 9 and a low-voltage coil 10 are both wound on the transformer magnetic column 5, a first inductor coil 11 is wound on the first inductor magnetic column 7, and a second inductor coil 12 is wound on the second inductor magnetic column 8; the common magnetic flux loop includes a magnetic path formed in the common magnetic wall 6.

[0037] The first magnetic chassis 3 and the second magnetic chassis 4 are used to support the transformer magnetic column 5, the common magnetic wall 6, the first inductor magnetic column 7 and the second inductor magnetic column 8, and also provide bottom and top pathways for the magnetic flux loop. In one application scenario, in order to reduce the hardware cost and size of the magnetic core, both the first magnetic chassis 3 and the second magnetic chassis 4 are rectangular plate structures.

[0038] The transformer core 5 is used for winding the high-voltage coil 9 and the low-voltage coil 10, and is the main magnetic circuit part of the transformer core 1. The shared magnetic wall 6 is the magnetic circuit part shared by the transformer core 1 and the dual-inductance core 2. A shared magnetic flux loop is formed in the shared magnetic wall 6, such as... Figure 3 As shown, the dashed lines represent the magnetic field loops of the two inductors, and the solid lines represent the direction of the current. Figure 3 The shaded area represents the magnetic field cancellation region. The first inductor post 7 is used for winding the first inductor coil 11, and the second inductor post 8 is used for winding the second inductor coil 12. Together, they form the main magnetic circuit of the dual inductor core 2.

[0039] It should be noted that the integrated magnetic core is formed by two integrally formed magnetic core blocks abutting each other. For ease of understanding, for example, the first magnetic core block includes a first magnetic base 3 and a transformer magnetic column 5, a common magnetic wall 6, a first inductor magnetic column 7, and a second inductor magnetic column 8 disposed on the first magnetic base 3. The second magnetic core block includes a second magnetic base 4. After the two magnetic core blocks abut each other, the transformer magnetic column 5, the common magnetic wall 6, the first inductor magnetic column 7, and the second inductor magnetic column 8 are all located between the first magnetic base 3 and the second magnetic base 4. Alternatively, the same surface of the first magnetic base 3 may have a portion of each of the transformer magnetic column 5, the common magnetic wall 6, the first inductor magnetic column 7, and the second inductor magnetic column 8, and the same surface of the second magnetic base 4 may have another portion of the aforementioned magnetic columns and magnetic walls. After the first magnetic base 3 and the second magnetic base 4 abut each other, the various parts are joined together to form a complete transformer magnetic column 5, common magnetic wall 6, first inductor magnetic column 7, and second inductor magnetic column 8.

[0040] By adopting the above method, two magnetic core blocks are joined together to form an integrated magnetic core, so that the transformer core 1 and the dual-inductor core 2 share the magnetic flux circuit in the shared magnetic wall 6, achieving deep magnetic integration, reducing the volume of the core body and lowering the cost of raw materials.

[0041] In another embodiment of this application, the first inductor post 7 and the second inductor post 8 both have a magnetic gap 13 in the magnetic flux loop. The magnetic gap 13 is used to adjust the inductance of the first inductor coil 11 and the second inductor coil 12.

[0042] The magnetic gap 13 refers to the discontinuous portion of the first inductor magnetic column 7 and the second inductor magnetic column 8 in the magnetic flux loop, that is, the air gap between the magnetic column and the magnetic base or between the two parts of the magnetic column. The magnetic gap 13 can adjust the inductance. With the same number of coil turns, the wider the gap, the smaller the inductance, and the less likely the inductance is to saturate; conversely, the smaller the gap, the larger the inductance, which means a larger average magnetic flux density, but the inductance is more likely to saturate.

[0043] For ease of understanding, the direction between the first magnetic base 3 and the second magnetic base 4 is defined as the height direction. The heights of both the first inductor magnetic column 7 and the second inductor magnetic column 8 are less than the height of the transformer magnetic column 5. This smaller height forms a magnetic gap 13. For example, a magnetic gap 13 is formed between the end face of the first inductor magnetic column 7 away from the first magnetic base 3 and the second magnetic base 4, and a magnetic gap 13 is also formed between the end face of the second inductor magnetic column 8 away from the first magnetic base 3 and the second magnetic base 4.

[0044] In a specific application scenario, when the circuit system requires a total output inductance of 2uH, the 2uH inductance is divided into two 1uH inductors and connected in series. By adjusting the width of the magnetic gap 13 on the first inductor magnetic post 7 and the second inductor magnetic post 8, the inductance of each inductor is 1uH, and the total inductance after the two are connected in series is 2uH.

[0045] By using the above method, by setting a magnetic gap 13 on the first inductor post 7 and the second inductor post 8, the inductance of the first inductor coil 11 and the second inductor coil 12 can be adjusted, so that the inductance of the two inductors can be flexibly configured to meet the requirements of different output voltage power levels.

[0046] In another embodiment of this application, both the transformer magnetic column 5 and the common magnetic wall 6 are closed magnets, and the closed magnets do not have a magnetic gap 13 in the magnetic flux loop.

[0047] In this context, a closed magnet refers to a magnetic column or magnetic wall that is uninterrupted in the magnetic flux loop. Specifically, the two ends of the transformer magnetic column 5 are connected to the first magnetic base 3 and the second magnetic base 4, respectively, and the two ends of the shared magnetic wall 6 are also connected to the first magnetic base 3 and the second magnetic base 4, respectively. No air gaps pass through the magnetic flux loop. Because the transformer magnetic column 5 and the shared magnetic wall 6 are both closed magnetic columns without gaps, the magnetic flux loop formed between the transformer magnetic column 5, the first magnetic base 3, the shared magnetic wall 6, and the second magnetic base 4 will not pass through any gaps.

[0048] Correspondingly, the first inductive magnetic column 7 and the second inductive magnetic column 8 are gap magnetic columns with gaps. The magnetic flux loop formed between the first inductive magnetic column 7, the first magnetic base 3, the common magnetic wall 6 and the second magnetic base 4 passes through the magnetic gap 13, and the magnetic flux loop formed between the second inductive magnetic column 8, the first magnetic base 3, the common magnetic wall 6 and the second magnetic base 4 also passes through the magnetic gap 13.

[0049] Using the above method, the transformer magnetic column 5 and the common magnetic wall 6 are closed magnets, which ensures the high permeability and low magnetic resistance of the transformer magnetic circuit and improves the energy transfer efficiency of the transformer; at the same time, the first inductor magnetic column 7 and the second inductor magnetic column 8 have magnetic gaps 13, which makes the inductance adjustable and the inductance less prone to saturation.

[0050] In another embodiment of this application, in the same direction perpendicular to the cross-section of the first inductor 7 or the second inductor 8, the current flow direction of the first inductor coil 11 around the first inductor 7 is opposite to the current flow direction of the second inductor coil 12 around the second inductor 8.

[0051] The opposite current flow direction refers to the following: when observed from the same direction perpendicular to the cross-section of the first inductor coil 7 or the second inductor coil 8, if the current flow in the first inductor coil 11 is clockwise, then the current flow in the second inductor coil 12 is counterclockwise, and vice versa. To determine the opposite current flow direction, it is necessary to ensure that the current flow direction of the first inductor coil 11 around the first inductor coil 7 and the current flow direction of the second inductor coil 12 around the second inductor coil 8 are observed from the same direction. This same direction can be perpendicular to the cross-section of the first inductor coil 7 (i.e., perpendicular to the end face of the first inductor coil 7) or perpendicular to the cross-section of the second inductor coil 8 (i.e., perpendicular to the end face of the second inductor coil 8).

[0052] For ease of understanding, since the first inductor coil 11 and the second inductor coil 12 are connected in series in the circuit, when current flows through the two inductors, by restricting the winding direction of the two inductors, the current in the two inductors flows in opposite directions in the same direction perpendicular to the cross-section of the magnetic column.

[0053] By using the above method, by restricting the current flow in the first inductor coil 11 and the second inductor coil 12 to be opposite, the magnetic fields generated by the first inductor coil 11 and the second inductor coil 12 cancel each other out in the common magnetic wall 6 without interfering with each other, thereby reducing the average magnetic flux density of the magnetic core body, reducing the heat generation of the magnetic core body from the source, and improving the conversion efficiency.

[0054] In another embodiment of this application, such as Figure 4As shown, the high-voltage side filter includes a first capacitor C1; the high-voltage side H-bridge includes a first power semiconductor Q1, a second power semiconductor Q2, a third power semiconductor Q3, and a fourth power semiconductor Q4, with the first power semiconductor Q1 and the second power semiconductor Q2 forming the first bridge arm, and the third power semiconductor Q3 and the fourth power semiconductor Q4 forming the second bridge arm; the full-bridge rectifier includes a fifth power semiconductor Q5, a sixth power semiconductor Q6, a seventh power semiconductor Q7, and an eighth power semiconductor Q8, with the fifth power semiconductor Q5 and the seventh power semiconductor Q7 forming the third bridge arm, and the sixth power semiconductor Q6 and the eighth power semiconductor Q8 forming the second bridge arm. 8 forms the fourth bridge arm; the low-voltage side filter includes the second capacitor C3; one end of the high-voltage coil 9 is electrically connected between the second power semiconductor Q2 and the fourth power semiconductor Q4, and the other end of the high-voltage coil 9 is electrically connected between the first power semiconductor Q1 and the third power semiconductor Q3 through the DC blocking capacitor C2; one end of the low-voltage coil 10 is electrically connected between the fifth power semiconductor Q5 and the seventh power semiconductor Q7, and the other end of the low-voltage coil 10 is electrically connected between the sixth power semiconductor Q6 and the eighth power semiconductor Q8; the positive output port of the full-bridge rectifier is located on the parallel connection line of the fifth power semiconductor Q5 and the sixth power semiconductor Q6.

[0055] In this circuit, the first capacitor C1 is a high-voltage side filter capacitor used to filter out high-frequency ripple in the high-voltage side input DC power. The first power semiconductor Q1 to the fourth power semiconductor Q4 form the two arms of the high-voltage side H-bridge, converting DC power to high-frequency AC power through high-frequency switching. The fifth power semiconductor Q5 to the eighth power semiconductor Q8 form the two arms of the low-voltage side full-bridge rectifier, used to rectify the low-voltage AC power output from the transformer into DC power. The second capacitor C3 is a low-voltage side filter capacitor used to filter out ripple in the output DC power.

[0056] It should be noted that in practical applications, each group of switching transistors in the first power semiconductor Q1 to the eighth power semiconductor Q8 can be connected in parallel with multiple switching transistors according to the current carrying capacity requirements, so as to improve the current carrying capacity and power level.

[0057] In one embodiment, the power semiconductors of Q1 to Q8 include one or more of SiC, IGBT, MOSFET and GaN.

[0058] For ease of understanding, such as Figure 4The diagram shows the circuit topology of the DC-DC power converter provided in this embodiment. One end of the high-voltage coil 9 is connected to the midpoint between the second power semiconductor Q2 and the fourth power semiconductor Q4, and the other end is connected to the midpoint between the first power semiconductor Q1 and the third power semiconductor Q3 through the DC blocking capacitor C2. One end of the low-voltage coil 10 is connected to the midpoint between the fifth power semiconductor Q5 and the seventh power semiconductor Q7, and the other end is connected to the midpoint between the sixth power semiconductor 6 and the eighth power semiconductor Q8. The positive output port of the full-bridge rectifier is located on the parallel connection line of the fifth power semiconductor Q5 and the sixth power semiconductor Q6, that is, the common anode port of the upper tubes of the two bridge arms, and one end of the first inductor coil 11 is connected to this positive output port.

[0059] Using the above method, through specific circuit connections, a complete power conversion circuit was realized, consisting of high-voltage H-bridge inverter, transformer isolation step-down, and low-voltage full-bridge rectification, providing a hardware foundation for subsequent control methods.

[0060] This application also provides a control method for the above-mentioned DC-DC power converter, which will be further described below.

[0061] like Figure 5 and Figure 6 As shown, the method includes: If the DC-DC power converter needs to be in the first state, then the second power semiconductor Q2 and the third power semiconductor Q3 are turned on simultaneously, and the first power semiconductor Q1 and the fourth power semiconductor Q4 are turned off. Additionally, the fifth power semiconductor Q5 and the eighth power semiconductor Q8 are turned on simultaneously, and the sixth power semiconductor Q6 and the seventh power semiconductor Q7 are turned off simultaneously, forming the first rectifier branch on the low-voltage side. The current loop of the first rectifier branch is as follows: low-voltage coil 10, fifth power semiconductor Q5, first inductor coil 11, second inductor coil 12, low-voltage side filter, eighth power semiconductor Q8, and back to low-voltage coil 10.

[0062] If the DC-DC power converter needs to be in the second state, the first power semiconductor Q1 and the fourth power semiconductor Q4 are turned on simultaneously, while the second power semiconductor Q2 and the third power semiconductor Q3 are turned off. The sixth power semiconductor Q6 and the seventh power semiconductor Q7 are also turned on simultaneously, while the fifth power semiconductor Q5 and the eighth power semiconductor Q8 are turned off simultaneously, forming the second rectifier branch on the low-voltage side. The current loop of the second rectifier branch is as follows: low-voltage coil 10, sixth power semiconductor Q6, first inductor coil 11, second inductor coil 12, low-voltage side filter, seventh power semiconductor Q7, and back to low-voltage coil 10.

[0063] The first and second states are two energy transfer states in the phase-shifted full-bridge control. In the first state, the second power semiconductor Q2 and the third power semiconductor Q3 on the high-voltage side are turned on simultaneously. The current on the high-voltage side flows from the DC blocking capacitor through the node between the first power semiconductor 1 and the third power semiconductor Q3, the high-voltage coil 9, and the node between the second power semiconductor Q2 and the fourth power semiconductor Q4 back. At this time, the corresponding voltage is induced on the low-voltage side of the transformer, and the fifth power semiconductor Q5 and the eighth power semiconductor Q8 are turned on. The current flows from the low-voltage coil 10 through the fifth power semiconductor Q5, the first inductor coil 11, the second inductor coil 12, the low-voltage side filter device, and the eighth power semiconductor Q8 back to the low-voltage coil 10, forming the first rectifier branch.

[0064] In the second state, the first power semiconductor Q1 and the fourth power semiconductor Q4 on the high-voltage side are turned on simultaneously, and the current direction on the high-voltage side is reversed. At this time, the low-voltage side of the transformer induces a voltage in the opposite direction, and the sixth power semiconductor Q6 and the seventh power semiconductor Q7 are turned on. The current flows from the low-voltage coil 10 through the sixth power semiconductor Q6, the first inductor coil 11, the second inductor coil 12, the low-voltage side filter device, and the seventh power semiconductor Q7 back to the low-voltage coil 10, forming the second rectifier branch.

[0065] It should be noted that in both the first and second states, the dual-series inductor is in an energy storage state, and the current slope shows an upward trend. In other words, in the energy transmission state, the transformer outputs energy to the low-voltage side, the inductor current gradually increases, and the inductor stores energy.

[0066] For ease of understanding, for example, under the conditions of a turns ratio of 12, an input voltage of 800V, and an output voltage of 27V, the DC-DC power converter switches between the first and second states, and realizes energy transfer and output voltage regulation by controlling the turn-on and turn-off timing of the switching transistor.

[0067] By adopting the above method, the energy transmission control of the phase-shifted full-bridge is realized by controlling the turn-on and turn-off sequence of the high-voltage and low-voltage side switching transistors. Two rectifier branches are formed in the first and second states respectively, so that the low-voltage side of the transformer can achieve full-bridge rectification output without intermediate shaft head. At the same time, the dual series inductor device stores energy in the energy transmission state, ensuring the continuity of the output current.

[0068] In another embodiment of this application, the pulse signal control logic of the first power semiconductor Q1 and the third power semiconductor Q3 are opposite and are provided with a first dead time; the pulse signal control logic of the second power semiconductor Q2 and the fourth power semiconductor Q4 are opposite and are provided with a second dead time; the pulse signal control logic of the first power semiconductor Q1 and the second power semiconductor Q2 has a phase difference of 0 degrees to 180 degrees to control the current direction of the regulating low-voltage coil 10.

[0069] In this context, "opposite pulse signal control logic" refers to the opposite switching states of the two switches on the same bridge arm, i.e., when one is on, the other is off. The first power semiconductor Q1 and the third power semiconductor Q3 constitute the upper and lower transistors of the same bridge arm, while the second power semiconductor 2 and the fourth power semiconductor Q4 constitute the upper and lower transistors of the other bridge arm.

[0070] Dead time refers to the time interval between the upper transistor being turned off and the lower transistor being turned on in the same bridge arm. The purpose of setting dead time is to prevent short circuits in the bridge arm and damage to the machine. In one embodiment, the first dead time and the second dead time can be set according to the switching characteristics of the switching transistor and the circuit parameters.

[0071] The pulse signal control logic of the first power semiconductor Q1 and the second power semiconductor Q2 has a phase difference of 0 to 180 degrees. By adjusting the magnitude of this phase difference, the direction and magnitude of the current in the high-voltage coil 9 of the transformer are controlled, thereby adjusting the current direction in the low-voltage coil 10. When the phase difference is 0 degrees, no current flows through the high-voltage coil 9; when the phase difference is 180 degrees, the current in the high-voltage coil 9 reaches its maximum. By adjusting the phase difference between 0 and 180 degrees, the output voltage is regulated.

[0072] By adopting the above method, dead time is set to prevent bridge arm shoot-through short circuit, and the current direction of low voltage coil 10 is controlled by adjusting the phase difference, thus realizing phase-shifting control of the full-bridge phase-shifting, making the output voltage adjustable.

[0073] In another embodiment of this application, such as Figure 7 and Figure 8 As shown, the method also includes: If the DC-DC power converter needs to be in the third state, the first power semiconductor Q1 and the second power semiconductor Q2 are turned on simultaneously, the third power semiconductor Q3 and the fourth power semiconductor Q4 are turned off, and the fifth power semiconductor Q5, the sixth power semiconductor Q6, the seventh power semiconductor Q7 and the eighth power semiconductor Q8 are turned on simultaneously to form a freewheeling circuit on the low-voltage side.

[0074] If the DC-DC power converter needs to be in the fourth state, the third power semiconductor Q3 and the fourth power semiconductor Q4 are turned on simultaneously, while the first power semiconductor Q1 and the second power semiconductor Q2 are turned off. The fifth power semiconductor Q5, the sixth power semiconductor Q6, the seventh power semiconductor Q7 and the eighth power semiconductor Q8 are turned on simultaneously to form a freewheeling circuit on the low-voltage side.

[0075] The current loop of the freewheeling circuit is as follows: first inductor coil 11, second inductor coil 12, low-voltage side filter device, seventh power semiconductor Q7 and eighth power semiconductor Q8, fifth power semiconductor Q5 and sixth power semiconductor Q6, and back to first inductor coil 11.

[0076] In the first and second states, the dual-series inductor is in an energy storage state, and the current slope shows an upward trend. In the third and fourth states, the dual-series inductor is in a discharge state, and the current slope shows a downward trend.

[0077] The third and fourth states are two freewheeling states in the phase-shifted full-bridge control. In the third state, the first power semiconductor Q1 and the second power semiconductor Q2 on the high-voltage side are simultaneously turned on. At this time, the two ends of the high-voltage coil 9 are short-circuited, the transformer does not transmit energy, and all four switches on the low-voltage side are turned on, forming a freewheeling circuit. The energy stored in the inductor is released to the load through the freewheeling circuit, and the inductor current gradually decreases. The fourth state is similar to the third state, except that the switch turned on on the high-voltage side is different.

[0078] In the freewheeling circuit, the current starts from the first inductor coil 11, passes through the second inductor coil 12, the low-voltage side filter, the seventh power semiconductor Q7 and the eighth power semiconductor Q8, the fifth power semiconductor Q5 and the sixth power semiconductor Q6 in sequence, and finally returns to the first inductor coil 11, forming a closed freewheeling circuit.

[0079] It should be noted that in the first and second states, the dual-series inductor is in an energy storage state, and the current slope shows an upward trend; in the third and fourth states, the dual-series inductor is in a discharge state, and the current slope shows a downward trend. By switching between the energy storage state and the discharge state, the continuity of the output current and the stability of the output voltage are achieved.

[0080] For ease of understanding, for example: in a phase-shift control method, in a full-wave rectifier circuit with an intermediate shaft transformer, the reverse voltage plateau stress borne by the low-voltage side switching transistor is 2Vin / N, such as... Figure 9 and Figure 10 As shown in the figure, the Vds voltage simulation of Q5-Q8, under the conditions of a turns ratio of 12 for the high-voltage coil and 800VDC DC input and 27V DC output, the reverse plateau voltage stress of the switching transistor in the full-bridge rectifier circuit without an intermediate shaft transformer on the low-voltage side is Vin / N=800 / 12=66.7V, which corresponds to the theoretical calculation result (Note: N is the turns ratio of the high-voltage coil to the low-voltage coil, and Vin is the input high-voltage voltage).

[0081] By using the above method, a freewheeling circuit is formed in the third and fourth states by controlling the turn-on and turn-off sequence of the switching transistor, so that the dual series inductor device discharges in the freewheeling state, ensuring the continuity of the output current. At the same time, the output voltage is regulated by alternating between the energy storage and discharge states.

[0082] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A DC-DC power converter, characterized in that, include: High-voltage side filter device, high-voltage side H-bridge device, isolation device, full-bridge rectifier device, dual series inductor device and low-voltage side filter device; The isolation device includes a DC blocking capacitor and a transformer. The transformer includes a high-voltage coil, a low-voltage coil, and a transformer core. Both the high-voltage coil and the low-voltage coil are wound around the transformer core. The dual-series inductor device includes a first inductor coil, a second inductor coil, and a dual-inductor core, wherein the first inductor coil and the second inductor coil are wound in series around the dual-inductor core; The electrical signal of the DC-DC power converter flows sequentially through the high-voltage side filter, the high-voltage side H-bridge device, the isolation device, the full-bridge rectifier, the dual series inductor device, and the low-voltage side filter. One end of the first inductor is electrically connected to the positive output port of the full-bridge rectifier, and the other end of the first inductor is electrically connected to the second inductor.

2. The DC-DC power converter according to claim 1, characterized in that, The transformer core and the dual-inductor core are integrated cores with a shared magnetic flux loop.

3. The DC-DC power converter according to claim 2, characterized in that, The integrated magnetic core includes a first magnetic chassis and a second magnetic chassis, as well as a transformer magnetic column, a common magnetic wall, a first inductor magnetic column and a second inductor magnetic column located between the first magnetic chassis and the second magnetic chassis; The transformer core includes a first magnetic base, a second magnetic base, a transformer magnetic column, and a common magnetic wall. The dual-inductor core includes a first magnetic base, a second magnetic base, a first inductor magnetic column, a second inductor magnetic column, and a common magnetic wall. The high-voltage coil and the low-voltage coil are both wound on the transformer magnetic column. The first inductor coil is wound on the first inductor magnetic column, and the second inductor coil is wound on the second inductor magnetic column. The shared magnetic flux loop includes the magnetic path formed in the shared magnetic wall.

4. The DC-DC power converter according to claim 3, characterized in that, Both the first and second inductor magnetic pillars have magnetic gaps in the magnetic flux loop, and the magnetic gaps are used to adjust the inductance of the first and second inductor coils.

5. The DC-DC power converter according to claim 3, characterized in that, Both the transformer magnetic column and the shared magnetic wall are closed magnets, and the closed magnets do not have magnetic gaps in the magnetic flux loop.

6. The DC-DC power converter according to any one of claims 1 to 5, characterized in that, In the same direction perpendicular to the cross-section of the first inductor or the second inductor, the current flow of the first inductor coil around the first inductor is opposite to the current flow of the second inductor coil around the second inductor.

7. The DC-DC power converter according to any one of claims 1 to 5, characterized in that, The high-voltage side filter device includes a first capacitor; The high-voltage side H-bridge device includes a first power semiconductor, a second power semiconductor, a third power semiconductor, and a fourth power semiconductor. The first power semiconductor and the second power semiconductor constitute a first bridge arm, and the third power semiconductor and the fourth power semiconductor constitute a second bridge arm. The full-bridge rectifier includes a fifth power semiconductor, a sixth power semiconductor, a seventh power semiconductor, and an eighth power semiconductor. The fifth power semiconductor and the seventh power semiconductor constitute the third bridge arm, and the sixth power semiconductor and the eighth power semiconductor constitute the fourth bridge arm. The low-voltage side filter device includes a second capacitor; One end of the high-voltage coil is electrically connected between the second power semiconductor and the fourth power semiconductor, and the other end of the high-voltage coil is electrically connected between the first power semiconductor and the third power semiconductor through the DC blocking capacitor; one end of the low-voltage coil is electrically connected between the fifth power semiconductor and the seventh power semiconductor, and the other end of the low-voltage coil is electrically connected between the sixth power semiconductor and the eighth power semiconductor; The positive output port of the full-bridge rectifier is located on the parallel connection line of the fifth power semiconductor and the sixth power semiconductor.

8. A control method applied to the DC-DC power converter of claim 7, characterized in that, The method includes: If the DC-DC power converter needs to be in the first state, the second and third power semiconductors are turned on simultaneously, and the first and fourth power semiconductors are turned off. The fifth and eighth power semiconductors are turned on simultaneously, and the sixth and seventh power semiconductors are turned off simultaneously, forming the first rectifier branch on the low-voltage side. The current loop of the first rectifier branch is as follows: low-voltage coil, the fifth power semiconductor, the first inductor coil, the second inductor coil, the low-voltage side filter device, the eighth power semiconductor, and back to the low-voltage coil; If the DC-DC power converter needs to be in the second state, the first power semiconductor and the fourth power semiconductor are controlled to be turned on simultaneously, and the second power semiconductor and the third power semiconductor are turned off, and the sixth power semiconductor and the seventh power semiconductor are controlled to be turned on simultaneously, and the fifth power semiconductor and the eighth power semiconductor are turned off simultaneously, forming the second rectifier branch on the low-voltage side; The current loop of the second rectifier branch is as follows: the low-voltage coil, the sixth power semiconductor, the first inductor, the second inductor, the low-voltage side filter, the seventh power semiconductor, and back to the low-voltage coil.

9. The control method for a DC-DC power converter according to claim 8, characterized in that, The pulse signal control logic of the first power semiconductor and the third power semiconductor are opposite, and a first dead time is provided; the pulse signal control logic of the second power semiconductor and the fourth power semiconductor are opposite, and a second dead time is provided. The pulse signal control logic of the first power semiconductor and the second power semiconductor has a phase difference of 0 to 180 degrees to control the direction of current in the low-voltage coil.

10. The control method for a DC-DC power converter according to claim 8, characterized in that, The method further includes: If the DC-DC power converter needs to be in the third state, the first power semiconductor and the second power semiconductor are controlled to be turned on simultaneously, and the third power semiconductor and the fourth power semiconductor are turned off, and the fifth power semiconductor, the sixth power semiconductor, the seventh power semiconductor and the eighth power semiconductor are controlled to be turned on simultaneously to form a freewheeling circuit on the low-voltage side. If the DC-DC power converter needs to be in the fourth state, then the third power semiconductor and the fourth power semiconductor are controlled to be turned on simultaneously, and the first power semiconductor and the second power semiconductor are turned off, and the fifth power semiconductor, the sixth power semiconductor, the seventh power semiconductor and the eighth power semiconductor are controlled to be turned on simultaneously to form a freewheeling circuit on the low-voltage side; The current loop of the freewheeling circuit is as follows: the first inductor, the second inductor, the low-voltage side filter, the seventh and eighth power semiconductors, the fifth and sixth power semiconductors, and back to the first inductor. In the first and second states, the dual series inductor is in an energy storage state with an increasing current slope. In the third and fourth states, the dual series inductor is in a discharge state with a decreasing current slope.

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