A smoothing reactor and a power conversion circuit, a power electronic conversion system

Abstract

This invention provides a smoothing reactor, a power conversion circuit, and a power electronic conversion system, relating to the field of power conversion technology. The smoothing reactor includes a first magnetic core, a second magnetic core, main windings, auxiliary windings, and switches. At least two main windings are wound on the first and second magnetic cores; at least one auxiliary winding is wound on the second magnetic core, and the two ends of the auxiliary winding are connected by corresponding switches. By setting up a first and second magnetic core, the main windings are simultaneously wound on both cores. An auxiliary winding is set on the second magnetic core and a short-circuit turn structure is formed through a switch to suppress changing magnetic flux in the second magnetic core. This ensures that rapidly changing AC magnetic flux is primarily closed in the first magnetic core, while DC or slowly changing magnetic flux is primarily closed in the second magnetic core. This allows for optimized design of different magnetic cores for different magnetic flux characteristics, improving the design flexibility of the smoothing reactor's magnetic circuit structure and corresponding AC / DC inductance.

Description

Technical Field

[0001] This invention relates to the field of power conversion technology, and more specifically, to a smoothing reactor, a power conversion circuit, and a power electronic conversion system. Background Technology

[0002] In power electronic switching power supplies, power electronic converters, such as AC-DC or DC-DC converters, require smoothing reactors to perform filtering, energy storage, and current limiting functions, smoothing pulsating electrical parameters into stable DC current. In practical applications, the current flowing through the smoothing reactor typically contains both DC and AC components.

[0003] In related technologies, smoothing reactors typically employ a single-core structure, with the corresponding AC and DC inductor windings wound on the same core. This results in the DC and AC fluxes being closed in the same magnetic circuit, meaning the AC and DC inductance components are often determined by the same core parameters, making independent design difficult. Furthermore, in applications with high DC current, significant DC bias can easily form in the core, leading to increased core flux density and potential saturation. Meanwhile, AC fluxes typically have higher frequencies, generating additional losses within the core. Therefore, when using a single-core structure, core design often requires a trade-off between DC bias capability and AC losses, limiting the design flexibility of the smoothing reactor's magnetic circuit structure and corresponding inductance. Summary of the Invention

[0004] The problem solved by this invention is: how to improve the design flexibility of the magnetic circuit structure of the smoothing reactor, so as to realize the flexible design of the AC and DC inductance of the smoothing reactor.

[0005] To address the above problems, this invention provides a smoothing reactor, a power conversion circuit, and a power electronic conversion system.

[0006] In a first aspect, the present invention provides a smoothing reactor, comprising a first magnetic core, a second magnetic core, a main winding, an auxiliary winding, and a switch, wherein at least two of the main windings are wound on the first magnetic core and the second magnetic core; at least one of the auxiliary windings is wound on the second magnetic core, and the two ends of the auxiliary winding are connected through the corresponding switch.

[0007] Optionally, the first magnetic core is made of a high-frequency, low-loss magnetic material; the second magnetic core is made of a high-saturation magnetic material.

[0008] Optionally, the first magnetic core includes a plurality of magnetic posts for carrying the main winding; and / or, the second magnetic core includes a plurality of magnetic posts for carrying the main winding and at least one magnetic post for a DC flux loop.

[0009] Optionally, at least one of the magnetic posts of the first magnetic core used to carry the main winding is provided with an air gap structure.

[0010] Optionally, at least one of the magnetic posts of the second magnetic core used to carry the main winding is provided with an air gap structure, and / or, at least one of the magnetic posts of the second magnetic core used for the DC flux circuit is provided with the air gap structure.

[0011] Optionally, at least one auxiliary winding is wound on the magnetic post of the second magnetic core on which the main winding is wound.

[0012] In a second aspect, the present invention provides a power conversion circuit, comprising at least two interleaved parallel power conversion branches and a smoothing reactor as described in the first aspect, wherein each main winding of the smoothing reactor is connected to each of the power conversion branches.

[0013] Optionally, the power conversion circuit further includes a power supply, a filter circuit, and a load, wherein the power supply, the power conversion branch, the filter circuit, and the load are connected in sequence.

[0014] Optionally, the switch of the smoothing reactor is configured to be turned on when the power conversion circuit is in normal operating condition and turned off when the power conversion circuit is in abnormal operating condition; wherein, the abnormal operating condition includes at least one of the power input failure and the load short circuit.

[0015] Thirdly, the present invention provides a power electronic conversion system, including a smoothing reactor as described in the first aspect, or a power conversion circuit as described in the second aspect.

[0016] The beneficial effects of the smoothing reactor, power conversion circuit, and power electronic conversion system of the present invention are as follows: The smoothing reactor of the present invention forms a magnetic circuit structure by setting a first magnetic core and a second magnetic core, and the main winding is wound on both the first and second magnetic cores simultaneously. This allows the magnetomotive force generated by the main winding to establish magnetic flux in the magnetic circuit formed by the two magnetic cores, thus enabling both magnetic cores to participate in the establishment of the magnetic circuit and increasing the design freedom of the magnetic circuit structure. Simultaneously, by setting at least one auxiliary winding wound on the second magnetic core and forming a short-circuit turn structure through switch closure, when the current change in the main winding generates a changing magnetic flux in the magnetic core, an induced current can be generated in the auxiliary winding, forming a magnetic flux with a trend opposite to the original changing magnetic flux, thereby suppressing the changing magnetic flux in the second magnetic core. Based on the above structural design, rapidly changing AC magnetic flux is difficult to form an effective closed magnetic circuit in the second magnetic core, and thus mainly closes in the first magnetic core, while DC magnetic flux or slowly changing magnetic flux mainly closes in the second magnetic core, thereby achieving a certain degree of separation between AC and DC magnetic flux in the magnetic circuit. By employing the aforementioned flux distribution method, the first and second magnetic cores can be optimized for different flux characteristics. For example, the first magnetic core can utilize high-frequency, low-loss magnetic materials to reduce core losses caused by AC flux, while the second magnetic core can utilize magnetic materials with higher saturation magnetic flux density to improve its carrying capacity under DC bias conditions. This avoids the design contradictions caused by the simultaneous closure of AC and DC fluxes in a single magnetic core in related technologies. In other words, the core needs both low high-frequency loss and high saturation magnetic flux density, eliminating the need for a compromise between these two factors. Thus, the smoothing reactor of this invention achieves the distribution adjustment of AC and DC fluxes on the magnetic circuit through a dual-core structure and an auxiliary winding short-circuit turn structure. This reduces core losses and improves the core's resistance to DC bias while maintaining the reactor's inductance performance, thereby enhancing the design flexibility of the smoothing reactor's magnetic circuit structure and its applicability in power electronic conversion systems. Attached Figure Description

[0017] Figure 1 This is a partial structural schematic diagram of the smoothing reactor in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the first magnetic core and the second magnetic core of the smoothing reactor in an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the second magnetic core in an embodiment of the present invention; Figure 4 This is a partial structural schematic diagram of the smoothing reactor in another embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of the first magnetic core and the second magnetic core of the smoothing reactor in another embodiment of the present invention; Figure 6This is a schematic diagram of the structure of the second magnetic core in another embodiment of the present invention; Figure 7 This is a partial circuit topology diagram of the power conversion circuit in an embodiment of the present invention. Detailed Implementation

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0019] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in sequences other than those illustrated or described herein.

[0020] Combination Figure 1 , Figure 4 As shown, an embodiment of the present invention provides a smoothing reactor, including a first magnetic core, a second magnetic core, a main winding, an auxiliary winding, and a switch. At least two main windings are wound on the first magnetic core and the second magnetic core; at least one auxiliary winding is wound on the second magnetic core, and the two ends of the auxiliary winding are connected by a corresponding switch.

[0021] In this embodiment, the smoothing reactor can be applied to a power conversion circuit, which includes a first magnetic core, a second magnetic core, a main winding, an auxiliary winding, and a switch.

[0022] The first and second magnetic cores form the magnetic circuit structure of the smoothing reactor. The first magnetic core forms the main closed magnetic circuit for the AC component flux, and the second magnetic core forms the main closed magnetic circuit for the DC component flux. At least two main windings are provided, each wound simultaneously on both the first and second magnetic cores. This allows the magnetomotive force generated by the main windings to establish flux in the magnetic circuit formed by the first and second magnetic cores. Each main winding can be connected to different power conversion branches of the power conversion circuit, allowing the current in each branch to establish flux in the core through the corresponding main winding. This creates magnetic coupling between the main windings, enabling the smoothing reactor to produce an inductive effect on current changes, suppressing current changes and achieving functions such as filtering, energy storage, or current limiting. At least one auxiliary winding is provided, wound on the second magnetic core, with its two ends connected by corresponding switches. When the switch is closed, the auxiliary winding forms a closed loop, thus forming a short-circuit turn structure on the second magnetic core in an electromagnetic sense, making the auxiliary winding a low-impedance closed loop (or the voltage at the auxiliary winding terminals is approximately 0). When the main winding current changes, generating a changing magnetic flux in the magnetic core, this changing magnetic flux induces an electromotive force and forms an induced current in the auxiliary winding. According to Lenz's law, the direction of the magnetic flux generated by this induced current is opposite to the original changing magnetic flux, thereby suppressing the changing magnetic flux in the second magnetic core and reducing the flow of AC magnetic flux in the second magnetic core. Based on the above structural design, the rapidly changing AC magnetic flux mainly forms a closed magnetic circuit in the first magnetic core, while the DC magnetic flux or the slowly changing magnetic flux mainly forms a closed magnetic circuit in the second magnetic core. This allows for the distribution of different magnetic flux components in different magnetic cores, facilitating the independent optimization design of the AC and DC component inductance in the smoothing reactor, thereby improving the design flexibility of the smoothing reactor's magnetic circuit structure and enabling flexible design of the AC and DC inductance values ​​of the smoothing reactor. Moreover, since different magnetic cores carry magnetic fluxes with different characteristics, the first and second magnetic cores can be optimized for different magnetic flux characteristics. For example, the first magnetic core can use high-frequency, low-loss magnetic materials to reduce losses caused by AC magnetic flux, while the second magnetic core can use high-saturation magnetic materials to improve the carrying capacity under DC bias conditions. This further enhances the design flexibility of the smoothing reactor's magnetic circuit structure and reduces the overall core loss, enabling flexible design of the AC and DC inductance of the smoothing reactor.

[0023] Furthermore, since the main winding is wound on both the first and second magnetic cores, both cores can jointly participate in establishing the magnetic circuit, thereby increasing the design freedom of the smoothing reactor's magnetic circuit structure and facilitating optimized design for different magnetic flux characteristics. The switching state of the auxiliary winding is controllable. By rationally configuring the core structure and controlling the closing state of the auxiliary winding, the distribution of varying magnetic flux in different cores can be adjusted, thereby optimizing the inductance characteristics of the smoothing reactor and improving its applicability in power electronic conversion systems.

[0024] In summary, this embodiment of the smoothing reactor utilizes a first and second magnetic core to form its magnetic circuit structure. The main winding is simultaneously wound on both cores, allowing the magnetomotive force generated by the main winding to establish magnetic flux within the magnetic circuit formed by the two cores. This enables both cores to participate in the magnetic circuit establishment, increasing the design freedom of the magnetic circuit structure. Simultaneously, by providing at least one auxiliary winding wound on the second core and forming a short-circuit turn structure through switch closure, when the main winding current changes, generating a changing magnetic flux in the core, an induced current is generated in the auxiliary winding, forming a magnetic flux with a trend opposite to the original changing magnetic flux. This suppresses the changing magnetic flux in the second core. Based on this structural design, rapidly changing AC magnetic flux is unlikely to form an effective closed magnetic circuit in the second core, thus primarily closing in the first core. Conversely, DC magnetic flux or slowly changing magnetic flux primarily closes in the second core, achieving a certain degree of separation between AC and DC magnetic flux in the magnetic circuit. By employing the aforementioned flux distribution method, the first and second magnetic cores can be optimized for different flux characteristics. For example, the first magnetic core can utilize high-frequency, low-loss magnetic materials to reduce core losses caused by AC flux, while the second magnetic core can utilize magnetic materials with higher saturation magnetic flux density to improve its carrying capacity under DC bias conditions. This avoids the design contradictions caused by the simultaneous closure of AC and DC fluxes in a single magnetic core in related technologies. In other words, the core needs both low high-frequency loss and high saturation magnetic flux density, eliminating the need for a compromise between these two factors. Thus, in this embodiment, the smoothing reactor achieves the distribution adjustment of AC and DC fluxes on the magnetic circuit through a dual-core structure and an auxiliary winding short-circuit turn structure. This reduces core losses and improves the core's resistance to DC bias while ensuring the reactor's inductance performance, thereby enhancing the design flexibility of the smoothing reactor's magnetic circuit structure and corresponding AC / DC inductance, and improving the smoothing reactor's applicability in power electronic conversion systems.

[0025] Optionally, the smoothing reactor may have at least one of two magnetic cores, namely the first magnetic core and the second magnetic core, in order to flexibly adapt to different needs and further improve the design flexibility of the magnetic circuit structure and corresponding AC / DC inductance of the smoothing reactor.

[0026] Optionally, the first and second magnetic cores can be arranged spatially in different ways according to actual structural requirements. For example, the first and second magnetic cores can be arranged side-by-side, stacked vertically, or arranged front-to-back, so that the main winding can be wound on both the first and second magnetic cores simultaneously, and a corresponding magnetic flux can be established in the magnetic circuit formed by the two magnetic cores. In some embodiments, considering the development requirements of miniaturization and high power density in power electronic conversion systems, the first and second magnetic cores of the smoothing reactor can also be arranged in a compact combined structure, for example, by being arranged adjacent to each other (e.g., Figure 1 , Figure 4 The overall structural volume is reduced by arranging the first and second magnetic cores in a front-to-back and close-fitting manner, sharing a part of the magnetic yoke, or using a partially nested arrangement. This ensures that the magnetic circuit of the smoothing reactor can be established normally and achieve magnetic flux closure, while reducing the overall volume of the smoothing reactor and improving the structural integration.

[0027] Optionally, the first magnetic core uses a high-frequency, low-loss magnetic material; the second magnetic core uses a high-saturation magnetic material.

[0028] In this embodiment, since the rapidly changing AC magnetic flux mainly forms a closed magnetic circuit in the first magnetic core, while the DC magnetic flux or the slowly changing magnetic flux mainly forms a closed magnetic circuit in the second magnetic core, appropriate magnetic materials can be selected for different magnetic flux characteristics.

[0029] Specifically, the first magnetic core primarily carries rapidly changing alternating current (AC) flux. Therefore, high-frequency, low-loss magnetic materials, such as ferrite or other magnetic materials with low high-frequency loss characteristics, can be used to reduce hysteresis and eddy current losses caused by the AC flux in the core, thereby reducing core temperature rise and improving reactor operating efficiency. Furthermore, since the first magnetic core primarily carries AC flux and does not need to simultaneously accommodate a large DC bias, its magnetic circuit design does not require additional redundancy for DC flux. This allows for a reduction in the size of the first magnetic core while still meeting the AC component inductance design requirements.

[0030] The second magnetic core primarily carries DC flux or slowly changing flux. Therefore, magnetic materials with high saturation magnetic flux density, such as silicon steel, iron powder cores, or other high saturation magnetic flux density materials, can be selected to improve the core's carrying capacity under DC bias conditions. This prevents the core from prematurely entering saturation under large DC current, thus ensuring the reactor maintains stable inductance characteristics. Furthermore, since the second magnetic core mainly carries DC flux, and the flow of AC flux is suppressed within it, the design of the second magnetic core does not need to focus on high-frequency AC loss control. This allows for reasonable control of the second magnetic core's size while meeting the DC component inductance design requirements.

[0031] Thus, through the aforementioned material configuration, the first and second magnetic cores can be optimized for different magnetic flux characteristics, thereby reducing core losses and improving the core's resistance to DC bias while ensuring the reactor's inductance performance. This also helps to minimize the increase in size caused by balancing both AC and DC magnetic flux in each core. Compared to related technologies where AC and DC fluxes are closed within the same core, requiring a trade-off between high-frequency loss and saturation magnetic flux density in the core material, this embodiment uses different magnetic materials for the first and second magnetic cores of the smoothing reactor. This allows for more suitable magnetic material support for the two magnetic flux characteristics in different cores, thereby improving the overall performance of the smoothing reactor and facilitating the miniaturization of the smoothing reactor's core structure.

[0032] Optionally, combined Figures 1-6 As shown, the first magnetic core includes a plurality of magnetic posts for carrying the main winding; and / or, the second magnetic core includes a plurality of magnetic posts for carrying the main winding and at least one magnetic post for a DC flux loop.

[0033] In this embodiment, the first magnetic core may be provided with multiple magnetic posts for carrying the main winding, and the magnetic posts are connected by magnetic yokes to form a magnetic circuit structure. The main winding may be wound on the corresponding magnetic posts so that the current in the main winding establishes magnetic flux in the first magnetic core. When the current in the main winding changes, the changing magnetic flux can form a closed magnetic circuit through the magnetic posts and magnetic yoke of the first magnetic core, thereby enabling the first magnetic core to undertake the main path of alternating magnetic flux.

[0034] Alternatively, the second magnetic core may have multiple magnetic posts for carrying the main winding and at least one magnetic post for a DC flux loop. These magnetic posts are connected by a yoke to form a magnetic circuit structure, providing the main flow path for the DC flux. Specifically, the magnetic post for the DC flux loop is connected to the corresponding magnetic post carrying the main winding via a yoke to form a DC flux loop, thus providing the main flow path for the DC flux. By including a magnetic post for the DC flux loop in the second magnetic core, the DC flux can have a more defined closed path, which is beneficial for carrying larger DC flux and reducing the impact of DC bias on other parts of the magnetic circuit.

[0035] Alternatively, the first magnetic core may have multiple magnetic posts for carrying the main winding, with the posts connected by a yoke to form a corresponding magnetic circuit structure; and the second magnetic core may have multiple magnetic posts for carrying the main winding and at least one magnetic post for a DC flux circuit, with the posts connected by a yoke to form a corresponding magnetic circuit structure. This allows the first magnetic core to handle the main path of AC flux, and the second magnetic core to handle the main path of DC flux. It also facilitates the simultaneous winding of the main winding on corresponding magnetic posts of both the first and second magnetic cores, providing a stable winding position for the main winding. This allows the main winding to form effective magnetic coupling between the two magnetic cores, enabling the smoothing reactor to rationally distribute flux between the different magnetic cores.

[0036] Thus, through the above-mentioned magnetic column structure design, the distribution of magnetic flux between the first and second magnetic cores can be further optimized, so that AC and DC magnetic flux can form the main closed magnetic circuits in different magnetic cores, thereby improving the design flexibility of the smoothing reactor's magnetic circuit structure and the corresponding AC and DC inductance, and improving the overall performance of the smoothing reactor.

[0037] Optionally, combined Figure 2 , Figure 5 As shown, at least one magnetic post of the first magnetic core used to carry the main winding has an air gap structure.

[0038] In this embodiment, at least one magnetic post of the first magnetic core used to carry the main winding is provided with an air gap structure to increase the equivalent magnetic reluctance in the magnetic circuit of the first magnetic core, thereby reducing the magnetic flux density in the first magnetic core and improving the anti-saturation capability of the first magnetic core under the condition of current change.

[0039] Specifically, since the rapidly changing alternating magnetic flux mainly forms a closed magnetic circuit in the first magnetic core, when the current in the main winding changes, the alternating magnetic flux establishes a magnetic circuit between the magnetic pillars and the yoke of the first magnetic core. By setting air gaps on the corresponding magnetic pillars used to carry the main winding, the amplitude of the change in magnetic flux density of the alternating magnetic flux in the first magnetic core can be effectively reduced, making the first magnetic core less likely to enter a saturation state during alternating current changes, thus reducing the risk of the first magnetic core entering a saturation state and ensuring that the smoothing reactor can maintain stable inductance characteristics. In addition, by setting air gaps on the corresponding magnetic pillars used to carry the main winding, the equivalent permeability in the magnetic circuit can also be reduced, thereby improving the energy storage capacity of the smoothing reactor and enhancing the reactor's suppression of current changes.

[0040] For example, the first magnetic core may have an air gap structure only on some of the magnetic posts used to carry the main winding, or it may have an air gap structure on all the magnetic posts used to carry the main winding, to optimize the distribution of AC magnetic flux in the first magnetic core. For example, as Figure 2As shown in the figure, the first magnetic core with two magnetic poles includes two U-shaped (or C-shaped) parts. The two U-shaped (or C-shaped) parts with opposite openings form a square-shaped structure. Each U-shaped (or C-shaped) part includes two magnetic pole parts and a magnetic yoke connecting the two magnetic pole parts. When the two U-shaped (or C-shaped) parts are arranged oppositely and combined, the magnetic pole parts of one part are relatively matched with the corresponding magnetic pole parts of the other part, thereby forming two magnetic poles for carrying the main winding. These two magnetic poles form a closed magnetic circuit through the corresponding magnetic yokes. A gap can be reserved between the end faces of the relatively matched magnetic pole parts to form an air-gap structure. The alternating magnetic flux forms a magnetic circuit through the air-gap part when passing through these magnetic poles. By setting an air-gap at the end face of the magnetic pole part, the equivalent magnetic resistance in the magnetic circuit of the first magnetic core can be increased, thereby reducing the amplitude of the change in magnetic flux density in the magnetic core, improving the anti-saturation ability of the first magnetic core under the action of alternating magnetic flux, and by reasonably setting the air-gap structure, the magnetic circuit characteristics of the alternating magnetic flux can be adjusted, thereby improving the stability and anti-saturation ability of the smoothing reactor under the condition of alternating current change. Similarly, as Figure 5 shown in the figure, the first magnetic core with three magnetic poles includes two E-shaped parts. The two E-shaped parts with opposite openings form a structure like a Chinese character 'Ri'. Each E-shaped part includes three magnetic pole parts and a magnetic yoke connecting each magnetic pole part. When the two E-shaped parts are arranged oppositely and combined, the corresponding magnetic pole parts cooperate with each other to form a three-magnetic-pole structure for carrying the main winding and forming a closed magnetic circuit through the magnetic yoke. In this structure, an air-gap structure can also be set between the end faces of the corresponding magnetic pole parts to achieve the adjustment of the magnetic circuit characteristics of the alternating magnetic flux. By analogy, according to the actual number of magnetic poles required or the winding arrangement requirements of the main winding, etc., the number of magnetic poles and the magnetic core structure of the first magnetic core can be correspondingly configured. For example, a magnetic core structure with two, three or more magnetic poles can be formed by combining different-shaped magnetic core parts, so that each magnetic pole can be used to carry the main winding and form a corresponding magnetic circuit structure, thereby adapting to the power levels or winding arrangement requirements of different power conversion circuits. Through the above structural design, while ensuring that the alternating magnetic flux mainly forms a closed magnetic circuit in the first magnetic core, the flexible matching of the magnetic pole structure and the main winding arrangement method can be achieved, thereby further improving the structural adaptability of the smoothing reactor and the design flexibility of the corresponding magnetic circuit and the AC / DC inductance values.

[0041] Optionally, in combination with Figures 1-6 shown in the figure, at least one magnetic pole of the second magnetic core for carrying the main winding is provided with an air-gap structure, and / or at least one magnetic pole of the second magnetic core for the DC magnetic flux loop is provided with an air-gap structure.

[0042] In this embodiment, since the second magnetic core mainly carries DC magnetic flux or magnetic flux with relatively slow changes, an air gap structure is provided in at least one magnetic column of the second magnetic core to increase the equivalent magnetic resistance in the magnetic circuit of the second magnetic core, thereby reducing the magnetic flux density in the second magnetic core and improving the anti-saturation ability of the second magnetic core under DC bias conditions. And through this air gap structure, the influence of DC bias on the magnetic core can be effectively alleviated, so that the magnetic core is not easily saturated under the action of a large DC current, thereby ensuring that the reactor can maintain stable inductance characteristics.

[0043] Specifically, an air gap structure may be provided in at least one magnetic column of the second magnetic core for carrying the main winding, so that when the DC magnetic flux passes through this magnetic column, a magnetic circuit is formed through the air gap part, thereby increasing the equivalent magnetic resistance in the magnetic circuit, reducing the change amplitude of the magnetic flux density of the DC magnetic flux in the magnetic core, and making the second magnetic core not easily saturated under the action of a large DC current.

[0044] Alternatively, an air gap structure is provided in at least one magnetic column of the second magnetic core for the DC magnetic flux loop, so that the DC magnetic flux passing through this magnetic column forms a magnetic circuit through the air gap, thereby increasing the equivalent magnetic resistance of the DC magnetic circuit and reducing the magnetic flux density in this magnetic column to further improve the carrying capacity of the second magnetic core under DC bias conditions.

[0045] Alternatively, an air gap structure is provided in at least one magnetic column of the second magnetic core for carrying the main winding, and an air gap structure is also provided in at least one magnetic column of the second magnetic core for the DC magnetic flux loop, so that the DC magnetic flux forms a magnetic circuit through the air gap part in multiple magnetic columns, thereby adjusting the magnetic flux distribution in the second magnetic core and further improving the anti-saturation ability of the overall magnetic circuit of the second magnetic core.

[0046] Thus, through the above setting of the air gap structure, the magnetic circuit characteristics of the second magnetic core can be adjusted according to the distribution of the DC magnetic flux, so that the second magnetic core has better anti-saturation ability when carrying the DC magnetic flux, thereby improving the stability and reliability of the smoothing reactor in the power electronic conversion system.

[0047] Exemplarily, as Figure 1-3 shown, the second magnetic core with three magnetic columns (such as two magnetic columns for carrying the main winding and one magnetic column for the DC magnetic flux loop) has a structure in the shape of a Chinese character 'Ri'; an air gap structure can be set on any magnetic column of the second magnetic core. As Figure 1 shown, in this second magnetic core structure, the two magnetic columns on both sides can be used to carry the main winding, so that the main winding can be wound around the corresponding magnetic column to enable the current in the main winding to establish magnetic flux in the second magnetic core; the magnetic column in the middle can be used as the magnetic column for the DC magnetic flux loop to provide a main circulation path for the DC magnetic flux, so that the DC magnetic flux can form a closed magnetic circuit through this magnetic column and the corresponding yoke. In addition, as Figure 3As shown, an air gap structure can be set on the two magnetic pillars located on both sides; or as shown in the figure. Figure 1 , Figure 3 As shown, an air gap structure can be set in the magnetic pillar located in the middle. Similarly, as... Figure 4-6 As shown, a second magnetic core with four magnetic pillars (such as three pillars for carrying the main winding and one pillar for the DC flux circuit) is arranged in a U-shape; an air gap structure can be set on any of the magnetic pillars of the second magnetic core. Figure 4 , Figure 5 As shown, in this second magnetic core structure, three magnetic pillars on the same side can be used to support the main winding, allowing the main winding to be wound on the corresponding magnetic pillars so that the current in the main winding can establish magnetic flux in the second magnetic core; the magnetic pillar on the other side can serve as a magnetic pillar for a DC magnetic flux circuit, providing the main flow path for the DC magnetic flux, allowing the DC magnetic flux to form a closed magnetic circuit through the magnetic pillar and the corresponding yoke. Furthermore, as... Figure 4 , Figure 5 As shown, an air gap structure can be set up with three magnetic pillars located on the same side; or as... Figure 6 As shown, an air gap structure can be set in one of the magnetic pillars located on one side. Similarly, the number of magnetic pillars and the core structure of the second magnetic core can be configured according to the actual number of magnetic pillars required or the main winding requirements. For example, a core structure with two, three, or more magnetic pillars can be formed by combining magnetic core parts of different shapes, allowing each magnetic pillar to support the main winding and form a corresponding magnetic circuit structure, thereby adapting to the power levels or winding arrangement requirements of different power conversion circuits. Through the above structural design, while ensuring that the AC magnetic flux mainly forms a closed magnetic circuit in the second magnetic core, a flexible match between the magnetic pillar structure and the main winding arrangement can be achieved, thereby further improving the structural adaptability of the smoothing reactor and the design flexibility of the corresponding magnetic circuit and AC / DC inductance.

[0048] Optionally, combined Figure 1 , Figure 4 As shown, at least one auxiliary winding is wound on the magnetic post of the second magnetic core on which the main winding is wound.

[0049] In this embodiment, at least one auxiliary winding is wound on the magnetic post of the second magnetic core on which the main winding is wound. The auxiliary winding is wound on the magnetic post of the second magnetic core to support the main winding, thus forming a magnetic coupling relationship between the auxiliary winding and the main winding at the corresponding magnetic post. Since the current in the main winding establishes magnetic flux in the magnetic core, when the main winding current changes, the changing magnetic flux establishes a corresponding magnetic circuit in the second magnetic core. By setting an auxiliary winding on the magnetic post on which the main winding is wound, the auxiliary winding can be made more sensitive to changes in magnetic flux in the magnetic post, thereby enabling the auxiliary winding to more effectively sense the changing magnetic flux in the magnetic post. When the auxiliary winding closes through a corresponding switch to form a closed loop, the auxiliary winding forms a short-circuit turn structure in an electromagnetic sense. When the change in the main winding current generates a changing magnetic flux in the second magnetic core, this changing magnetic flux induces an electromotive force and forms an induced current in the auxiliary winding. According to Lenz's law, the direction of the magnetic flux generated by this induced current is opposite to the trend of the original changing magnetic flux, thereby suppressing the changing magnetic flux in the second magnetic core and reducing the flow of alternating magnetic flux in the second magnetic core.

[0050] Thus, by placing the auxiliary winding on the magnetic post on which the main winding is wound, a strong magnetic coupling relationship can be formed between the auxiliary winding and the main winding. This allows the auxiliary winding to more effectively suppress the changing magnetic flux in the second magnetic core, further reducing the flow of AC magnetic flux in the second magnetic core. This is beneficial for the second magnetic core to mainly carry DC magnetic flux, while the rapidly changing AC magnetic flux mainly forms a closed magnetic circuit in the first magnetic core, thereby improving the rationality and stability of the smoothing reactor's magnetic circuit design.

[0051] Combination Figure 7 As shown, another embodiment of the present invention provides a power conversion circuit, including at least two interleaved parallel power conversion branches and the above-mentioned smoothing reactor, wherein each main winding of the smoothing reactor is connected to each power conversion branch.

[0052] In this embodiment, the power conversion circuit (such as BUCK circuit, Boost circuit or Buck-Boost circuit, etc.) can be applied to switching power supplies, battery charging and discharging systems or other power electronic conversion systems to achieve stable regulation of current or voltage.

[0053] A power conversion circuit includes at least two interleaved parallel power conversion branches (i.e., a functional branch in the power conversion circuit used to achieve power conversion, which typically includes at least one switching device (such as...) Figure 7The switching devices Q1 and Q2 shown, along with their cooperating energy storage and / or rectifier elements, are used to transfer and regulate electrical energy between the input and output terminals under the control of the switching devices. Each power conversion branch is connected in an interleaved parallel configuration, meaning the switching devices in each parallel power conversion branch operate according to a preset phase difference, thus creating a time-phased distribution of the current in each power conversion branch. For example, in the case of two power conversion branches, the switching signals of the two branches can differ by 180°; in the case of three power conversion branches, the switching signals of each power conversion branch can differ by 120° to achieve interleaved operation. Through this interleaved parallel configuration, the current ripple generated by each power conversion branch can be staggered in time, thereby reducing the overall current ripple and increasing the equivalent switching frequency of the power conversion circuit, which is beneficial for improving the dynamic response performance and operational stability of the system.

[0054] Based on the above-mentioned interleaved parallel power conversion branches, the DC component of the current in each branch (such as...) Figure 7 The DC components Idc1 and Idc2 shown are basically in phase, while the AC ripple components (such as...) Figure 7 There is a phase difference between the DC components Iac1 and Iac2 shown in the diagram. Each main winding of the smoothing reactor is connected to its corresponding power conversion branch, allowing the current in each branch to flow through its corresponding main winding, thereby establishing magnetic flux in the core. Since the DC components of the branch currents are essentially in phase, the DC flux generated by each main winding can superimpose and form a closed magnetic circuit in the low-frequency, high-saturation core; while, due to the phase difference in time between the AC ripple components of the branch currents, the AC flux generated by each main winding mainly forms a closed magnetic circuit in the high-frequency, low-loss core. Therefore, the separation of AC and DC flux in the magnetic circuit can be achieved, allowing different cores to be optimized for different frequency characteristics. For example, the high-frequency, low-loss core can be mainly used to carry AC flux to reduce core loss caused by high-frequency flux, while the high-saturation magnetic flux density core can be mainly used to carry DC flux to improve the core's carrying capacity under DC bias conditions, thereby reducing core loss and increasing the flexibility of inductor design (such as AC / DC inductor inductance design). Meanwhile, the multiple main windings of the smoothing reactor are connected to each branch, so that the currents of multiple branches form a magnetic coupling relationship in the same magnetic structure, which helps to further reduce current ripple and improve current distribution, thereby improving the overall efficiency and stability of the power conversion circuit.

[0055] Furthermore, because the smoothing reactor employs a composite magnetic circuit structure of a first core and a second core, rapidly changing AC magnetic flux primarily forms a closed magnetic circuit in the first core, while DC magnetic flux or slower-changing magnetic flux primarily forms a closed magnetic circuit in the second core. Therefore, when this smoothing reactor is applied to an interleaved parallel power conversion circuit, the AC component of the current in each power conversion branch of the circuit can form the main magnetic flux path in the first core, while the DC component of the current in each power conversion branch mainly forms a magnetic circuit through the second core, thus distributing magnetic fluxes with different characteristics in different cores.

[0056] Thus, by employing at least two interleaved parallel power conversion branches and the aforementioned smoothing reactor, the AC ripple flux and DC flux in the power conversion circuit can be separated in the magnetic circuit structure. This allows the first and second magnetic cores to be optimized for different flux characteristics, improving the design flexibility of the smoothing reactor's magnetic circuit structure and the corresponding AC and DC inductance. For example, the first magnetic core can use a high-frequency, low-loss magnetic material to reduce losses caused by AC flux, while the second magnetic core can use a high-saturation magnetic material to improve its carrying capacity under DC bias conditions. This not only reduces current ripple in the power conversion circuit but also improves the stability of the smoothing reactor under DC bias conditions, thereby enhancing the efficiency and reliability of the entire power conversion circuit.

[0057] Optionally, combined Figure 7 As shown, the power conversion circuit also includes a power supply, a filter circuit, and a load, which are connected in sequence.

[0058] In this embodiment, the power supply of the power conversion circuit can provide input power to the power conversion circuit, such as a DC power supply, battery pack, or other power supply device. The output terminal of the power supply is connected to the power conversion branch, so that the power output can be converted into electrical energy through the power conversion branch. The power conversion branch is used to regulate the voltage or current of the input power, for example, by controlling the conduction and cutoff of switching devices to achieve energy transfer between the input and output terminals, and to realize power conversion functions such as step-down, step-up, or step-up / step-down as needed. Multiple power conversion branches can work in an interleaved parallel manner to reduce current ripple and improve the dynamic response performance of the system. A filter circuit is set between the power conversion branch and the load to filter the power output of the power conversion branch to reduce the ripple component in the voltage or current, thereby obtaining a more stable output voltage or current; such as Figure 7 As shown, the filter circuit includes a filter capacitor C1. The load (such as...) Figure 7The load R1 shown is connected to the filter circuit to consume or utilize the electrical energy processed by the power conversion circuit. For example, the load can be an electronic device, a battery system, or other electrical device.

[0059] Thus, through the above structural configuration, the power conversion circuit allows the electrical energy output from the power source to pass through the power conversion branch and the filter circuit in sequence before being supplied to the load. This enables stable regulation of the output voltage or current and improves the overall operational stability of the power conversion circuit.

[0060] Optionally, the switch of the smoothing reactor is configured to be turned on when the power conversion circuit is in normal operating condition and turned off when the power conversion circuit is in abnormal operating condition; wherein, the abnormal operating condition includes at least one of power input failure and load short circuit.

[0061] In this embodiment, based on the configuration of the auxiliary winding and corresponding switch in the smoothing reactor, the switch of the smoothing reactor (such as...) Figure 7 The controllable switches S1 and S2 (corresponding to different auxiliary windings) are configured to be on (closed) when the power conversion circuit is in normal operating condition, and off (open) when the power conversion circuit is in abnormal operating condition (such as power input failure, load short circuit, etc.). Specifically, when the power conversion circuit is in normal operating condition, the switches are closed, causing the auxiliary windings to form a closed loop, thereby forming a short-circuit turn structure on the second magnetic core in an electromagnetic sense. When the main winding current changes and generates a changing magnetic flux in the magnetic core, this changing magnetic flux can induce an electromotive force and form an induced current in the auxiliary winding. According to Lenz's law, the direction of the magnetic flux generated by this induced current is opposite to the trend of the original changing magnetic flux, thereby suppressing the changing magnetic flux in the second magnetic core. This makes it difficult for high-frequency AC magnetic flux to form a closed magnetic circuit in the second magnetic core, thus avoiding additional eddy current losses caused by high-frequency AC magnetic flux forming a magnetic flux loop through the low-frequency, high-saturation magnetic core. Meanwhile, the aforementioned short-circuit turn structure allows the reactor to maintain the expected flux distribution even when there is some imbalance in the interleaved currents, thus ensuring the smoothing reactor's performance. Under abnormal operating conditions, such as when a load short-circuit occurs, the switch can be opened, preventing the auxiliary winding from forming a closed loop. In this case, the AC flux in the second core is no longer suppressed by the short-circuit turn, increasing the AC component inductance of the reactor. This helps suppress short-circuit inrush currents when there is a delay in fault detection and protection actions, thereby improving the fault suppression capability of the power conversion circuit. Furthermore, when the power input fails, the switch can also be opened, leaving the auxiliary winding in an open-circuit state. In this case, the energy stored in the DC inductance of the reactor can continue to be released to the load side through the circuit, maintaining power supply to the load for a period after the power input disappears. This helps extend the duration of power supply to the load and improves the stability of the system power supply.

[0062] Thus, through the above control method, the auxiliary winding can suppress AC magnetic flux when the power conversion circuit is working normally, and can change the electromagnetic characteristics of the reactor according to different operating conditions under abnormal operating conditions, thereby improving the adaptability of the smoothing reactor under different operating conditions and the operational reliability of the entire power conversion circuit.

[0063] Another embodiment of the present invention provides a power electronic conversion system, including the smoothing reactor or the power conversion circuit described above.

[0064] In this embodiment, the power electronic conversion system employs the aforementioned smoothing reactor or a power conversion circuit using the aforementioned smoothing reactor, enabling AC and DC magnetic fluxes to form main closed magnetic circuits in different magnetic cores of the smoothing reactor, thereby achieving flux separation. This allows for optimized design of different magnetic cores for magnetic fluxes with different frequency characteristics, facilitates reduction of core losses in the power electronic conversion system, and improves the flexibility of magnetic circuit design. Furthermore, the interleaved parallel power conversion structure of the power conversion circuit helps reduce current ripple and improve the dynamic response performance of the power electronic conversion system, thereby enhancing the overall efficiency and operational stability of the power electronic conversion system.

Claims

1. A smoothing reactor, characterized in that, It includes a first magnetic core, a second magnetic core, a main winding, an auxiliary winding, and a switch. At least two of the main windings are wound on the first magnetic core and the second magnetic core. At least one of the auxiliary windings is wound on the second magnetic core, and the two ends of the auxiliary winding are connected through the corresponding switch.

2. The smoothing reactor as described in claim 1, characterized in that, The first magnetic core is made of a high-frequency, low-loss magnetic material; the second magnetic core is made of a high-saturation magnetic material.

3. The smoothing reactor as described in claim 1 or 2, characterized in that, The first magnetic core includes a plurality of magnetic posts for carrying the main winding; and / or, the second magnetic core includes a plurality of magnetic posts for carrying the main winding and at least one magnetic post for a DC flux circuit.

4. The smoothing reactor as described in claim 3, characterized in that, At least one of the magnetic posts of the first magnetic core used to carry the main winding has an air gap structure.

5. The smoothing reactor as described in claim 3, characterized in that, At least one of the magnetic posts of the second magnetic core used to carry the main winding is provided with an air gap structure, and / or at least one of the magnetic posts of the second magnetic core used in the DC flux circuit is provided with the air gap structure.

6. The smoothing reactor as described in claim 3, characterized in that, At least one auxiliary winding is wound on the magnetic post of the second magnetic core on which the main winding is wound.

7. A power conversion circuit, characterized in that, It includes at least two interleaved parallel power conversion branches and a smoothing reactor as described in any one of claims 1-6, wherein each main winding of the smoothing reactor is connected to each of the power conversion branches.

8. The power conversion circuit as described in claim 7, characterized in that, It also includes a power supply, a filter circuit, and a load, wherein the power supply, the power conversion branch, the filter circuit, and the load are connected in sequence.

9. The power conversion circuit as described in claim 8, characterized in that, The switch of the smoothing reactor is configured to be turned on when the power conversion circuit is in normal operation and turned off when the power conversion circuit is in abnormal operation; wherein, the abnormal operation includes at least one of the power input failure and the load short circuit.

10. A power electronic conversion system, characterized in that, It includes the smoothing reactor as described in any one of claims 1-6, or the power conversion circuit as described in any one of claims 7-9.

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