Wide voltage regulation range and low current ripple isolated DC-DC converter and its control method

Abstract

This invention discloses an isolated DC-DC converter with a wide voltage regulation range and low current ripple, and its control method. The converter includes a high-voltage side split capacitor, a high-voltage side full-bridge circuit, a first high-frequency isolation energy channel, a second high-frequency isolation energy channel, a low-voltage side split capacitor, a low-voltage side half-bridge circuit, a low-voltage side full-bridge circuit, and interleaved parallel inductors. The interleaved parallel inductors and the low-voltage side full-bridge circuit together form an interleaved parallel Buck / Boost DC-DC converter topology; the low-voltage side full-bridge circuit, the first high-frequency isolation energy channel, and the high-voltage side full-bridge circuit together form a dual active bridge DC-DC converter topology; and the low-voltage side half-bridge circuit, the low-voltage side split capacitor, the second high-frequency isolation energy channel, the high-voltage side full-bridge circuit, and the high-voltage side split capacitor together form a fully resonant DC-DC converter topology. This isolated DC-DC converter compensates for the lower efficiency of the main power channel under light load and wide voltage variation ranges, ensuring high efficiency over a wide voltage and power range.

Description

Technical Field

[0001] This invention belongs to the field of power electronic device technology, specifically relating to an isolated DC-DC converter with a wide voltage regulation range and low current ripple, and its control method. Background Technology

[0002] Currently, new energy power generation technology and the electric vehicle industry are developing rapidly, and energy storage systems have become an indispensable key component. Energy storage systems often require a large number of power electronic converters to manage battery charging and discharging, and the characteristics of batteries place unique demands on these power electronic converters. For example, battery port voltage fluctuates significantly during normal charging and discharging; battery life is greatly affected by the ripple of the charging and discharging current, and low current ripple can improve battery life; battery short circuits can cause extremely serious safety problems, and external factors causing battery short circuits must be strictly avoided. These battery characteristics require power electronic converters to have a wide voltage regulation range, high efficiency across the entire voltage range, low battery port current ripple, and superior battery port short-circuit protection capabilities.

[0003] Currently, power electronic devices used for battery management are mainly divided into two categories based on the presence or absence of a transformer: non-isolated and isolated. Isolated devices are more practical in high-power battery charging and discharging scenarios (such as electric vehicle charging) due to their electrical isolation capabilities. Currently, isolated devices capable of providing high power often employ topologies based on dual active bridge DC-DC converters or resonant DC-DC converters. Both of these topologies use voltage source ports for battery connection, which cannot provide continuous low-ripple current, thus often requiring an external current filter. Furthermore, short-circuit faults in these converters can cause battery short circuits, increasing safety hazards. Additionally, these two mainstream topologies struggle to maintain high efficiency across a wide range of battery port voltages; their voltage regulation range is often limited to a narrow interval. Summary of the Invention

[0004] To address the problems existing in current isolated bidirectional DC-DC converter topologies, this invention aims to provide an isolated DC-DC converter with a wide voltage regulation range and low current ripple, along with its control method. This isolated DC-DC converter compensates for the lower efficiency of the main power channel under light load and wide voltage variation ranges, ensuring high efficiency of the converter over a wide voltage and power range.

[0005] The objective of this invention is achieved through the following technical solutions:

[0006] In a first aspect, the present invention provides an isolated DC-DC converter with a wide voltage regulation range and low current ripple, characterized in that it includes a high-voltage side split capacitor, a high-voltage side full-bridge circuit, a first high-frequency isolation energy channel, a second high-frequency isolation energy channel, a low-voltage side split capacitor, a low-voltage side half-bridge circuit, a low-voltage side full-bridge circuit, and interleaved parallel inductors.

[0007] The high-voltage side split capacitor, high-voltage side full-bridge circuit, first high-frequency isolation energy channel, low-voltage side split capacitor, low-voltage side half-bridge circuit, low-voltage side full-bridge circuit, and interleaved parallel inductors are connected in sequence; the first high-frequency isolation energy channel and the second high-frequency isolation energy channel are connected in parallel.

[0008] The interleaved parallel inductors and the low-voltage side full-bridge circuit together form an interleaved parallel Buck / Boost DC-DC converter topology; the low-voltage side full-bridge circuit, the first high-frequency isolation energy channel, and the high-voltage side full-bridge circuit together form a dual active bridge DC-DC converter topology; the low-voltage side half-bridge circuit, the low-voltage side split capacitor, the second high-frequency isolation energy channel, the switching devices Q3 and Q4 in the high-voltage side full-bridge circuit, and the high-voltage side split capacitor together form a fully resonant DC-DC converter topology.

[0009] As a further improvement of the present invention, the high-voltage side split capacitor includes capacitor C1 and capacitor C2, which are connected in series and then in parallel across the two ends of the high-voltage port; the midpoint between capacitor C1 and capacitor C2 is capacitor point C; capacitor point C is connected to one end of the primary side of the high-frequency transformer of the second high-frequency isolation energy channel.

[0010] As a further improvement of the present invention, the high-voltage side full-bridge circuit comprises switching devices Q1, Q2, Q3, and Q4. Switching devices Q1 and Q2 form one half-bridge with the midpoint of the bridge arm at point A. Switching devices Q3 and Q4 form the other half-bridge with the midpoint of the bridge arm at point B. The drains of switching devices Q1 and Q3 are connected together to form the positive DC terminal of the full-bridge circuit, and the sources of switching devices Q2 and Q4 are connected together to form the negative DC terminal of the full-bridge circuit. The DC side of the full-bridge circuit is connected in parallel with the high-voltage side split capacitor. Point A of the high-voltage side full-bridge circuit is connected to one end of the primary side of the high-frequency transformer of the first high-frequency isolation energy channel. Point B of the high-voltage side full-bridge circuit is connected to the other end of the primary side of the high-frequency transformer of the first high-frequency isolation energy channel. Point B of the high-voltage side full-bridge circuit is also connected to one end of the primary side of the high-frequency transformer of the second high-frequency isolation energy channel.

[0011] As a further improvement of the present invention, the first high-frequency isolated energy channel includes a high-frequency transformer and a series inductor Lk. The two ends of the primary side of the high-frequency transformer are connected between points A and B of the high-voltage side full-bridge circuit. One end of the secondary side of the high-frequency transformer is connected in series with the inductor Lk and then connected to the midpoint D of the low-voltage side full-bridge circuit. The other end of the secondary side of the high-frequency transformer is connected to the other midpoint E of the low-voltage side full-bridge circuit.

[0012] As a further improvement of the present invention, the second high-frequency isolated energy channel includes a high-frequency transformer, a resonant inductor Lr, and a resonant capacitor Cr; the two ends of the primary side of the high-frequency transformer are respectively connected between point B of the high-voltage side full-bridge circuit and point C of the high-voltage side split capacitor; one end of the secondary side of the high-frequency transformer is connected in series with the capacitor Cr and then connected to the midpoint F of the low-voltage side half-bridge circuit; the other end of the secondary side of the high-frequency transformer is connected in series with the inductor Lr and then connected to the midpoint G of the low-voltage side split capacitor.

[0013] As a further improvement of the present invention, the low-voltage side split capacitor includes two equal capacitors C3 and C4 connected in series; after being connected in series, capacitors C3 and C4 are connected in parallel across the DC side of the low-voltage side half-bridge circuit and the low-voltage side full-bridge circuit; the midpoint between capacitors C3 and C4 is denoted as point G.

[0014] As a further improvement of the present invention, the low-voltage side half-bridge circuit includes switching device S5 and switching device S6; the midpoint connecting switching device S5 and switching device S6 is F; the drain of switching device S5 is the positive DC-side terminal of the low-voltage side half-bridge circuit; the source of switching device S6 is the negative DC-side terminal of the low-voltage side half-bridge circuit; the low-voltage side half-bridge circuit, together with the low-voltage side split capacitor, the second high-frequency isolation energy channel, switching device Q3 and switching device Q4 in the high-voltage side full-bridge circuit, and the high-voltage side split capacitor, constitute a fully resonant DC-DC converter topology.

[0015] As a further improvement of the present invention, the low-voltage side full-bridge circuit comprises four switching devices S1, S2, S3, and S4. Switching devices S1 and S2 form one half-bridge with the midpoint of the bridge arm at point D. Switching devices S3 and S4 form the other half-bridge with the midpoint of the bridge arm at point E. The drains of switching devices S1 and S3 are connected together to form the positive DC-side terminal of the low-voltage side full-bridge circuit. The sources of switching devices S2 and S4 are connected together to form the negative DC-side terminal of the low-voltage side full-bridge circuit. The negative DC-side terminal of the low-voltage side full-bridge circuit is connected to the negative terminal of the battery port. Points D and E of the low-voltage side full-bridge circuit are respectively connected to one end of inductors L1 and L2 in the interleaved parallel inductors. The low-voltage side full-bridge circuit, together with the first high-frequency isolated energy channel and the high-voltage side full-bridge circuit, constitute a dual active bridge DC-DC converter topology.

[0016] As a further improvement of the present invention, the interleaved parallel inductors include inductor L1 and inductor L2; one end of inductor L1 and inductor L2 are respectively connected to points D and E of the low-voltage side full-bridge circuit; the other end of inductor L1 and inductor L2 are connected to the positive terminal of the battery port; the interleaved parallel inductors and the low-voltage side full-bridge circuit together constitute an interleaved parallel Buck / Boost DC-DC converter topology.

[0017] Secondly, the present invention provides a control method for an isolated DC-DC converter with a wide voltage regulation range and low current ripple, comprising:

[0018] High-voltage side split capacitors filter out high-frequency current components flowing through the high-voltage port;

[0019] The upper and lower switching devices of the two half-bridges in the high-voltage side full-bridge circuit are complementary and conduct with a 50% duty cycle. There is an adjustable phase shift angle between the two half-bridges, which generates an adjustable high-frequency AC voltage, thereby controlling the power flowing through the first high-frequency isolation energy channel.

[0020] By adjusting the phase shift angle of the high-voltage side full-bridge circuit and the low-voltage side full-bridge circuit, the voltage is adjusted, thereby controlling the current and energy flowing through the first high-frequency isolation energy channel, and finally realizing the power transfer between the high-voltage port and the battery port.

[0021] The low-voltage side half-bridge circuit and the high-voltage side full-bridge circuit operate synchronously, so that the voltage on the resonant cavity of the second high-frequency isolation energy channel is a two-level high-frequency AC square wave voltage.

[0022] The low-voltage side split capacitor filters out the high-frequency current component on the low-voltage DC side, providing a stable low-voltage DC side voltage;

[0023] The driving signals of the two half-bridges in the low-voltage side full-bridge circuit are phase-shifted by 180 degrees to generate a positive and negative balanced high-frequency AC voltage. By adjusting the phase of this high-frequency AC voltage, the energy flowing through the first high-frequency isolated energy channel can be freely controlled. The turns ratio of the battery port voltage and the low-voltage side DC side voltage can be adjusted to adapt to a wide range of battery voltage variations.

[0024] The ripples of the current in the interleaved parallel inductors cancel each other out.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] To address the problems of existing isolated bidirectional DC-DC converter topologies, this invention proposes a novel isolated DC-DC converter topology that integrates the features of dual active bridge DC-DC converter topologies, fully resonant DC-DC converter topologies, and interleaved parallel Buck / Boost DC-DC converter topologies. This topology possesses the advantages of all three. First, it features the large inductance of the interleaved parallel Buck / Boost DC-DC converter topology. This inductor is directly connected to the battery port, thus ensuring the continuity of the battery port current and low ripple. The inductor also provides short-circuit protection to prevent battery damage from converter failures. The topology also features a main power path based on the dual active bridge DC-DC converter topology. The excellent soft-switching performance of the dual active bridge DC-DC converter topology ensures the converter's efficiency under heavy loads. Furthermore, the topology has a secondary power path constructed from a fully resonant DC-DC converter topology, which compensates for the lower efficiency of the main power path under light loads and wide voltage variations, ensuring high efficiency of the converter over a wide voltage and power range.

[0027] The interleaved parallel inductors in the topology of this invention can effectively suppress current ripple at the battery port and provide short-circuit protection for the battery port. The interleaved parallel Buck / Boost DC-DC converter topology of this invention, composed of interleaved parallel inductors and a low-voltage side full-bridge circuit, has a wide-range voltage regulation capability, which can adapt to a wide range of voltage variations at the battery port. The dual active bridge DC-DC converter topology of this invention, composed of a low-voltage side full-bridge circuit, a first high-frequency isolation energy channel, and a high-voltage side full-bridge circuit, has excellent soft-switching performance, ensuring the efficiency of the converter under heavy load. The fully resonant DC-DC converter topology of this invention, composed of a low-voltage side half-bridge circuit, a low-voltage side split capacitor, a second high-frequency isolation energy channel, switching devices Q3 and Q4 in the high-voltage side full-bridge circuit, and a high-voltage side split capacitor, can compensate for the lower efficiency of the main power channel under light load and wide voltage variation range, ensuring high efficiency of the converter over a wide voltage and power range. Attached Figure Description

[0028] 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a topology diagram of the isolated DC-DC converter with wide voltage regulation range and low current ripple of the present invention.

[0030] Figure 2This is a topology diagram of the isolated DC-DC converter with wide voltage regulation range and low current ripple of the present invention when applied to unidirectional (high voltage port to battery port) power transmission;

[0031] Figure 3 This is a topology diagram of the isolated DC-DC converter with wide voltage regulation range and low current ripple of the present invention when applied to unidirectional (battery port to high voltage port) power transmission;

[0032] Figure 4 This is another equivalent topology diagram of the isolated DC-DC converter with wide voltage regulation range and low current ripple of the present invention;

[0033] Figure 5 This is another equivalent topology diagram of the isolated DC-DC converter with wide voltage regulation range and low current ripple of the present invention. Detailed Implementation

[0034] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0035] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more. In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0036] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. 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 the present invention.

[0037] The purpose of this invention is to construct an isolated DC-DC converter with a wide voltage regulation range and low current ripple. Its topology consists of switching devices, capacitors, inductors, and a high-frequency isolation transformer. The converter has bidirectional power regulation capability, enabling battery charge and discharge management. The converter exhibits low-ripple charge and discharge current during battery charging and discharging to ensure battery life. The converter's battery connection port has short-circuit protection to prevent short circuits caused by converter short circuits. The converter has a wide voltage regulation range and high efficiency across the entire voltage regulation range.

[0038] The first objective of this invention is to provide an isolated DC-DC converter with a wide voltage regulation range and low current ripple, such as... Figure 1 As shown, it includes a high-voltage side split capacitor 1, a high-voltage side full-bridge circuit 2, a first high-frequency isolation energy channel 3, a second high-frequency isolation energy channel 4, a low-voltage side split capacitor 5, a low-voltage side half-bridge circuit 6, a low-voltage side full-bridge circuit 7, and an interleaved parallel inductor 8.

[0039] The interleaved parallel inductor 8 and the low-voltage side full-bridge circuit 7 together form an interleaved parallel Buck / Boost DC-DC converter topology; the low-voltage side full-bridge circuit 7, the first high-frequency isolation energy channel 3, and the high-voltage side full-bridge circuit 2 together form a dual active bridge DC-DC converter topology; the low-voltage side half-bridge circuit 6, the low-voltage side split capacitor 5, the second high-frequency isolation energy channel 4, the switching devices Q3 and Q4 in the high-voltage side full-bridge circuit 2, and the high-voltage side split capacitor together form a fully resonant DC-DC converter topology.

[0040] This invention can be applied to battery charge and discharge management scenarios. The topology constructed in this invention integrates the characteristics of dual active bridge DC-DC converter topologies, fully resonant DC-DC converter topologies, and interleaved parallel Buck / Boost DC-DC converter topologies. Compared to traditional converters composed of only a single type of topology, this invention simultaneously possesses the advantages of multiple different topologies.

[0041] The high-voltage side split capacitor 1 is composed of two equal capacitors, C1 and C2, connected in series. After being connected in series, capacitors C1 and C2 are connected in parallel across the high-voltage port. The midpoint between capacitors C1 and C2 is denoted as capacitor point C. Capacitor point C is connected to one end of the primary winding of the high-frequency transformer in the second high-frequency isolation energy channel 4.

[0042] The high-voltage side full-bridge circuit 2 consists of four switching devices Q1, Q2, Q3, and Q4. Switching devices Q1 and Q2 form one half-bridge, with the midpoint of the bridge arm denoted as A. Switching devices Q3 and Q4 form the other half-bridge, with the midpoint of the bridge arm denoted as B. The drains of switching devices Q1 and Q3 are connected together to form the positive DC terminal of the full-bridge circuit, and the sources of switching devices Q2 and Q4 are connected together to form the negative DC terminal of the full-bridge circuit. The DC side of the full-bridge circuit is connected in parallel with the high-voltage side split capacitor 1. Point A of the high-voltage side full-bridge circuit 2 is connected to one end of the primary winding of the high-frequency transformer in the first high-frequency isolation energy channel 3. Point B of the high-voltage side full-bridge circuit 2 is connected to the other end of the primary winding of the high-frequency transformer in the first high-frequency isolation energy channel 3. Simultaneously, point B of the high-voltage side full-bridge circuit 2 is also connected to one end of the primary winding of the high-frequency transformer in the second high-frequency isolation energy channel 4.

[0043] The first high-frequency isolated energy channel 3 consists of a high-frequency transformer and a series inductor Lk. The two ends of the primary winding of the high-frequency transformer are connected between points A and B of the high-voltage side full-bridge circuit 2. One end of the secondary winding of the high-frequency transformer is connected in series with the inductor Lk and then connected to the midpoint D of the low-voltage side full-bridge circuit 7. The other end of the secondary winding of the high-frequency transformer is connected to the other midpoint E of the low-voltage side full-bridge circuit 7. The series inductor Lk can be the leakage inductance of the high-frequency transformer itself or an external inductor. This inductor can be connected in series with either the primary or secondary winding of the high-frequency transformer.

[0044] The second high-frequency isolated energy channel 4 consists of a high-frequency transformer, a resonant inductor Lr, and a resonant capacitor Cr. The two ends of the primary side of the high-frequency transformer are connected between point B of the high-voltage side full-bridge circuit 2 and point C of the high-voltage side split capacitor 1, respectively. One end of the secondary side of the high-frequency transformer is connected in series with capacitor Cr and then connected to the midpoint F of the low-voltage side half-bridge circuit 6. The other end of the secondary side of the high-frequency transformer is connected in series with inductor Lr and then connected to the midpoint G of the low-voltage side split capacitor 5. The resonant inductor Lr can be the leakage inductance of the high-frequency transformer itself or an external inductor. Capacitor Cr and inductor Lr can be connected in series on either the primary or secondary side of the high-frequency transformer. Alternatively, capacitor Cr and inductor Lr can be connected in series at the same end of either the primary or secondary side of the high-frequency transformer.

[0045] The low-voltage side split capacitor 5 is composed of two equal capacitors C3 and C4 connected in series. After being connected in series, capacitors C3 and C4 are connected in parallel across the DC side of both the low-voltage side half-bridge circuit 6 and the low-voltage side full-bridge circuit 7. The midpoint between capacitors C3 and C4 is denoted as point G.

[0046] The low-voltage side half-bridge circuit 6 consists of two switching devices S5 and S6. The midpoint connecting switching devices S5 and S6 is denoted as F. The drain of switching device S5 is denoted as the positive DC-side terminal of the low-voltage side half-bridge circuit 6. The source of switching device S6 is denoted as the negative DC-side terminal of the low-voltage side half-bridge circuit 6. The low-voltage side half-bridge circuit 6, together with the low-voltage side split capacitor 5, the second high-frequency isolation energy channel 4, the switching devices Q3 and Q4 in the high-voltage side full-bridge circuit 2, and the high-voltage side split capacitor 1, constitute a fully resonant DC-DC converter topology. This fully resonant DC-DC converter topology is the secondary power channel of the topology of this invention.

[0047] The low-voltage side full-bridge circuit 7 consists of four switching devices S1, S2, S3, and S4. Switching devices S1 and S2 form one half-bridge, with the midpoint of the bridge arm denoted as D. Switching devices S3 and S4 form the other half-bridge, with the midpoint of the bridge arm denoted as E. The drains of switching devices S1 and S3 are connected together to form the positive DC-side terminal of the low-voltage side full-bridge circuit 7. The sources of switching devices S2 and S4 are connected together to form the negative DC-side terminal of the low-voltage side full-bridge circuit 7. The negative DC-side terminal of the low-voltage side full-bridge circuit 7 is connected to the negative terminal of the battery port. Points D and E of the low-voltage side full-bridge circuit 7 are respectively connected to one end of inductors L1 and L2 in the interleaved parallel inductors 8. The low-voltage side full-bridge circuit 7, together with the first high-frequency isolated energy channel 3 and the high-voltage side full-bridge circuit 2, constitute a dual active bridge DC-DC converter topology. This dual active bridge DC-DC converter topology is the main power channel of the topology of this invention.

[0048] The interleaved parallel inductor 8 consists of inductor L1 and inductor L2. One end of inductor L1 and inductor L2 are connected to points D and E of the low-voltage side full-bridge circuit 7, respectively. The other ends of inductors L1 and L2 are connected to the positive terminal of the battery. The interleaved parallel inductor 8 and the low-voltage side full-bridge circuit 7 together form an interleaved parallel Buck / Boost DC-DC converter topology.

[0049] The second objective of this invention is to provide a control method for an isolated DC-DC converter with a wide voltage regulation range and low current ripple, comprising:

[0050] High-voltage side split capacitors filter out high-frequency current components flowing through the high-voltage port;

[0051] The upper and lower switching devices of the two half-bridges in the high-voltage side full-bridge circuit are complementary and conduct with a 50% duty cycle. There is an adjustable phase shift angle between the two half-bridges, which generates an adjustable high-frequency AC voltage, thereby controlling the power flowing through the first high-frequency isolation energy channel.

[0052] By adjusting the phase shift angle of the high-voltage side full-bridge circuit and the low-voltage side full-bridge circuit, the voltage is adjusted, thereby controlling the current and energy flowing through the first high-frequency isolation energy channel, and finally realizing the power transfer between the high-voltage port and the battery port.

[0053] The low-voltage side half-bridge circuit and the high-voltage side full-bridge circuit operate synchronously, so that the voltage on the resonant cavity of the second high-frequency isolation energy channel is a two-level high-frequency AC square wave voltage.

[0054] The low-voltage side split capacitor filters out the high-frequency current component on the low-voltage DC side, providing a stable low-voltage DC side voltage;

[0055] The driving signals of the two half-bridges in the low-voltage side full-bridge circuit are phase-shifted by 180 degrees to generate a positive and negative balanced high-frequency AC voltage. By adjusting the phase of this high-frequency AC voltage, the energy flowing through the first high-frequency isolated energy channel can be freely controlled. The turns ratio of the battery port voltage and the low-voltage side DC side voltage can be adjusted to adapt to a wide range of battery voltage variations.

[0056] The ripples of the current in the interleaved parallel inductors cancel each other out.

[0057] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0058] Please see Figure 1 As shown, an isolated DC-DC converter with a wide voltage regulation range and low current ripple according to the present invention includes: a high-voltage side split capacitor 1, a high-voltage side full-bridge circuit 2, a first high-frequency isolation energy channel 3, a second high-frequency isolation energy channel 4, a low-voltage side split capacitor 5, a low-voltage side half-bridge circuit 6, a low-voltage side full-bridge circuit 7, and an interleaved parallel inductor 8.

[0059] 1) The high-voltage side split capacitor 1 consists of two capacitors, C1 and C2. The two capacitors are connected in series and then in parallel at the positive and negative terminals of the high-voltage port to filter out the high-frequency current component flowing through the high-voltage port, ensuring the stability of the voltage at both ports. In addition, a high-frequency AC voltage can be generated between the midpoint capacitor C formed by the two capacitors connected in series and one midpoint B of the high-voltage side full-bridge circuit 2, allowing energy to flow freely between the primary and secondary sides of the high-frequency transformer through the second high-frequency isolation energy channel 4.

[0060] 2) The high-voltage side full-bridge circuit 2 consists of four switching devices Q1, Q2, Q3, and Q4. Switching devices Q1 and Q2 are connected in series in the forward direction, and switching devices Q3 and Q4 are connected in series in the forward direction, thus forming two half-bridges. The two half-bridges are connected in parallel to form the high-voltage side full bridge. The drains of switching devices Q1 and Q3 are called the positive DC terminals of the full-bridge circuit, and the sources of switching devices Q2 and Q4 are called the negative DC terminals of the full-bridge circuit. The DC side of the high-voltage side full-bridge circuit 2 is connected in parallel across the high-voltage port. The midpoints A and B of the two half-bridges of the high-voltage side full-bridge circuit 2 are connected to the primary winding of the high-frequency transformer of the first high-frequency isolation energy channel 3. The upper and lower switching devices of the two half-bridges of the high-voltage side full-bridge circuit 2 are complementary and conduct with a 50% duty cycle. There is an adjustable phase shift angle between the two half-bridges to generate an adjustable high-frequency AC voltage between points A and B, thereby controlling the power flowing through the first high-frequency isolation energy channel 3.

[0061] 3) The first high-frequency isolated energy channel 3 consists of a high-frequency transformer and a series inductor Lk. One side of the first high-frequency isolated energy channel 3 is connected between the two midpoints A and B of the high-voltage side full-bridge circuit 2, and the other side is connected between the two midpoints D and E of the low-voltage side full-bridge circuit 7. By adjusting the phase shift angle of the high-voltage side full-bridge circuit 2 and the low-voltage side full-bridge circuit 7, the voltage between midpoints A and B and between midpoints D and E can be adjusted, thereby regulating the current and energy flowing through the first high-frequency isolated energy channel 3, and ultimately realizing power transfer between the high-voltage port and the battery port.

[0062] 4) The second high-frequency isolated energy channel 4 consists of a high-frequency transformer, a resonant inductor Lr, and a resonant capacitor Cr. One side of the second high-frequency isolated energy channel 4 is connected between the midpoint B of the high-voltage side full-bridge circuit 2 and the midpoint capacitor C of the high-voltage side split capacitor 1, and the other side is connected between the midpoint F of the low-voltage side half-bridge circuit 6 and the midpoint G of the low-voltage side split capacitor 5. The switching devices S5 and S6 of the low-voltage side half-bridge circuit 6 operate synchronously with the switching devices Q3 and Q4 of the high-voltage side full-bridge circuit 2, respectively, so that the voltage on the resonant cavity of the second high-frequency isolated energy channel 4 is a two-level high-frequency AC square wave voltage. By reasonably designing the switching frequency and resonant cavity parameters, the voltage on the resonant cavity can make the resonant cavity operate in a fully resonant state, realizing the power self-balancing on both sides of the second high-frequency isolated energy channel 4, and ultimately realizing the power transmission between the high-voltage port and the battery port.

[0063] 5) The low-voltage side split capacitor 5 consists of two capacitors, C3 and C4. The two capacitors are connected in series and then in parallel across the DC side of the low-voltage side half-bridge circuit 6 and the low-voltage side full-bridge circuit 7. They are used to filter out the high-frequency current component on the low-voltage DC side and provide a stable low-voltage DC side voltage.

[0064] 6) The low-voltage side half-bridge circuit 6 consists of two switching devices, S5 and S6. Switching devices S5 and S6 are connected in series in the forward direction and then in parallel at the positive and negative terminals of the low-voltage side DC side. Switching devices S5 and S6 operate synchronously with switching devices Q3 and Q4 of the high-voltage side full-bridge circuit 2, respectively, ensuring that the high-frequency AC square wave voltage between points F and G is in phase and frequency with the high-frequency AC square wave voltage between points B and capacitor C. Simultaneously, the values ​​of the inductance Lr and capacitance Cr of the resonant cavity are designed so that their resonant frequency is equal to the frequency of the high-frequency AC square wave voltage between points F and G (or points B and capacitor C). Finally, the low-voltage side half-bridge circuit 6, the low-voltage side split capacitor 5, the second high-frequency isolation energy channel 4, the switching devices Q3 and Q4 in the high-voltage side full-bridge circuit 2, and the high-voltage side split capacitor 1 together constitute a fully resonant DC-DC converter topology. This fully resonant DC-DC converter topology allows for efficient energy flow between the high-voltage port and the battery port and has extremely low switching losses.

[0065] 7) The low-voltage side full-bridge circuit 7 consists of four switching devices: S1, S2, S3, and S4. Switching devices S1 and S2 form one half-bridge, and switching devices S3 and S4 form the other half-bridge. The drive signals of the two half-bridges are phase-shifted by 180 degrees to generate a positive-negative balanced high-frequency AC voltage between points D and E. By adjusting the phase of this high-frequency AC voltage relative to the high-frequency AC voltage between points A and B of the high-voltage side full-bridge circuit 2, the energy flowing through the first high-frequency isolation energy channel 3 can be freely controlled. Furthermore, the two half-bridges of the low-voltage side full-bridge circuit 7 and the interleaved parallel inductors 8 constitute an interleaved parallel Buck / Boost DC-DC converter topology. By adjusting the duty cycles of switching devices S1, S2, S3, and S4, the turns ratio of the battery port voltage and the low-voltage side DC-DC voltage (denoted as vinductance L) can be controlled, thereby adapting to a wide range of battery voltage variations.

[0066] 8) The interleaved parallel inductors 8 consist of inductors L1 and L2. Inductor L1, along with switching devices S1 and S2 in the low-voltage side full-bridge circuit 7, forms a bidirectional Bu capacitor Ck / Boo switching device St DC-DC converter topology. Inductor L2, along with switching devices S3 and S4 in the low-voltage side full-bridge circuit 7, forms another bidirectional Bu capacitor Ck / Boo switching device St DC-DC converter topology. As mentioned above, the half-bridge formed by switching devices S1 and S2 is 180 degrees phase-shifted relative to the half-bridge formed by switching devices S3 and S4. Therefore, the current ripple on inductors L1 and L2 can cancel each other out, ensuring low ripple and continuity of the battery port current.

[0067] The overall operation of the converter can be described as follows: For the dual active bridge DC-DC converter topology consisting of a high-voltage side full-bridge circuit 2, a first high-frequency isolation energy channel 3, and a low-voltage side full-bridge circuit 7, the high- and low-voltage side full-bridge circuit 7 regulates the power flow between the high and low voltage sides by adjusting the phase shift angle. The dual active bridge DC-DC converter topology has excellent soft-switching characteristics and low conduction losses, which can significantly increase the converter's efficiency under heavy load. For the fully resonant DC-DC converter topology consisting of a high-voltage side split capacitor 1, switching devices Q3 and Q4 of the high-voltage side full-bridge circuit 2, a second high-frequency isolation energy channel 4, a low-voltage side half-bridge circuit 6, and a low-voltage side split capacitor 5, its switching frequency and resonant cavity resonant frequency are designed to be the same, so that it operates in a fully resonant state. The fully resonant operating state has extremely low switching losses and allows power self-balancing between the high and low voltage sides, providing a secondary power channel, thereby reducing the current stress on the main power channel. For the interleaved parallel Buck / Boost DC-DC converter topology consisting of a low-voltage side full-bridge circuit 7 and interleaved parallel inductors 8, the duty cycle of the switching devices in the low-voltage side full-bridge circuit 7 can be used to regulate the turns ratio of the low-voltage side DC-side voltage and the battery port voltage, thereby adapting to a wide range of battery voltage variations. Furthermore, the interleaved parallel operation mode causes the ripple of the currents in inductors L1 and L2 to cancel each other out, resulting in lower ripple current at the battery port and improved battery life. Inductors L1 and L2 also suppress sudden changes in battery port current, thus providing short-circuit protection for the battery port.

[0068] This invention can have different structures in applications involving unidirectional power flow, combined with attached... Figure 2 , Figure 3 Please provide an explanation.

[0069] A topology of the wide voltage regulation range, low current ripple isolated DC-DC converter of the present invention is illustrated in the attached diagram when applied to unidirectional (high voltage port to battery port) power transmission. Figure 2 The topology and appendix Figure 1 The operating principle of the topology is the same. When power flows unidirectionally from the high-pressure side to the low-pressure side, the attached... Figure 1 In the intermediate topology, the current in switching devices S2, S4, S5, and S6 always flows in reverse. In this case, these switching devices can be replaced with diodes to reduce costs.

[0070] The invention relates to a topology for a wide voltage regulation range, low current ripple isolated DC-DC converter applied to unidirectional (battery port to high voltage port) power transmission, illustrated in the attached figure. Figure 3 The topology and appendix Figure 1 The operating principle of the topology is the same. When power flows unidirectionally from the low-pressure side to the high-pressure side, the attached... Figure 1In the intermediate topology, the current in switching devices S1, S3, Q3, and Q4 always flows in reverse. In this case, these switching devices can be replaced with diodes to reduce costs.

[0071] Another equivalent topology of the isolated DC-DC converter with wide voltage regulation range and low current ripple of the present invention is illustrated in the attached figure. Figure 4 Appendix Figure 4 The topology in the middle will be attached Figure 1 The split capacitor in the topology is removed, allowing resonant capacitors Cr1 and Cr2 to respectively bear half of the high-voltage DC-side voltage and half of the low-voltage DC-side voltage to avoid transformer magnetization. (Appendix) Figure 4 The principles and appendices of topology in Figure 1 The principles of topology are exactly the same.

[0072] Another equivalent topology of the wide voltage regulation range, low current ripple isolated DC-DC converter of the present invention is illustrated in the attached figure. Figure 5 Appendix Figure 5 The topology in the middle will be attached Figure 1 In the topology, the low-voltage side split capacitor 5 is removed, allowing the resonant capacitor Cr to bear half of the low-voltage side DC voltage to avoid transformer magnetization. (Appendix) Figure 5 The high-voltage side and the attached topology in the middle Figure 1 The topology and operating principle are exactly the same.

[0073] This invention is particularly suitable for battery charging and discharging scenarios requiring high safety, high current quality, high efficiency, and a wide voltage range, such as electric vehicle charging or integrated photovoltaic-energy storage scenarios.

[0074] It may replace some of the electric vehicle charging devices or battery management systems currently based on traditional topology types in the market, thus achieving certain economic benefits.

[0075] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

[0076] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still make modifications or equivalent substitutions to the specific implementation schemes of the present invention, and these modifications or equivalent substitutions do not depart from the spirit and scope of the present invention, and are all within the protection scope of the claims of the present invention.

Claims

1. An isolated DC-DC converter with a wide voltage regulation range and low current ripple, characterized in that, It includes a high-voltage side split capacitor, a high-voltage side full-bridge circuit, a first high-frequency isolation energy channel, a second high-frequency isolation energy channel, a low-voltage side split capacitor, a low-voltage side half-bridge circuit, a low-voltage side full-bridge circuit, and interleaved parallel inductors; The interleaved parallel inductors and the low-voltage side full-bridge circuit together form an interleaved parallel Buck / Boost DC-DC converter topology; the low-voltage side full-bridge circuit, the first high-frequency isolation energy channel, and the high-voltage side full-bridge circuit together form a dual active bridge DC-DC converter topology; the low-voltage side half-bridge circuit, the low-voltage side split capacitor, the second high-frequency isolation energy channel, the switching devices Q3 and Q4 in the high-voltage side full-bridge circuit, and the high-voltage side split capacitor together form a fully resonant DC-DC converter topology. The high-voltage side split capacitor includes capacitor C1 and capacitor C2; the midpoint between capacitors C1 and C2 is point C. The high-voltage side full-bridge circuit includes switching devices Q1, Q2, Q3, and Q4, wherein switching devices Q1 and Q2 form one half-bridge with the midpoint of the bridge arm A, and switching devices Q3 and Q4 form another half-bridge with the midpoint of the bridge arm B. The low-voltage side split capacitor includes two equal-value capacitors C3 and C4 connected in series; the midpoint between capacitors C3 and C4 is denoted as point G. The low-voltage side full-bridge circuit includes switching devices S1, S2, S3, and S4, wherein switching devices S1 and S2 form one half-bridge with the midpoint of the bridge arm D, and switching devices S3 and S4 form another half-bridge with the midpoint of the bridge arm E. The second high-frequency isolated energy channel includes a high-frequency transformer, a resonant inductor Lr, and a resonant capacitor Cr; the two ends of the primary side of the high-frequency transformer are respectively connected between point B of the high-voltage side full-bridge circuit and point C of the high-voltage side split capacitor; one end of the secondary side of the high-frequency transformer is connected in series with the capacitor Cr and then connected to the midpoint F of the low-voltage side half-bridge circuit; the other end of the secondary side of the high-frequency transformer is connected in series with the inductor Lr and then connected to the midpoint G of the low-voltage side split capacitor. The low-voltage side half-bridge circuit includes switching device S5 and switching device S6; the midpoint between the connection of switching device S5 and switching device S6 is F; the drain of switching device S5 is the positive DC-side terminal of the low-voltage side half-bridge circuit; the source of switching device S6 is the negative DC-side terminal of the low-voltage side half-bridge circuit; the low-voltage side half-bridge circuit, together with the low-voltage side split capacitor, the second high-frequency isolation energy channel, switching devices Q3 and Q4 in the high-voltage side full-bridge circuit, and the high-voltage side split capacitor, constitute a fully resonant DC-DC converter topology; The interleaved parallel inductors include inductor L1 and inductor L2; one end of inductor L1 and inductor L2 are respectively connected to points D and E of the low-voltage side full-bridge circuit; the other end of inductor L1 and inductor L2 are connected to the positive terminal of the battery port; the interleaved parallel inductors and the low-voltage side full-bridge circuit together form an interleaved parallel Buck / Boost DC-DC converter topology.

2. The isolated DC-DC converter with wide voltage regulation range and low current ripple according to claim 1, characterized in that, Capacitor C is connected to one end of the primary side of the high-frequency transformer of the second high-frequency isolation energy channel.

3. The isolated DC-DC converter with wide voltage regulation range and low current ripple according to claim 1, characterized in that, The drains of switching devices Q1 and Q3 are connected together to form the positive DC side of the full-bridge circuit, and the sources of switching devices Q2 and Q4 are connected together to form the negative DC side of the full-bridge circuit. The DC side of the full-bridge circuit is connected in parallel with the high-voltage side split capacitor. Point A of the high-voltage side full-bridge circuit is connected to one end of the primary side of the high-frequency transformer of the first high-frequency isolation energy channel. Point B of the high-voltage side full-bridge circuit is connected to the other end of the primary side of the high-frequency transformer of the first high-frequency isolation energy channel. Point B of the high-voltage side full-bridge circuit is also connected to one end of the primary side of the high-frequency transformer of the second high-frequency isolation energy channel.

4. The isolated DC-DC converter with wide voltage regulation range and low current ripple according to claim 3, characterized in that, The first high-frequency isolated energy channel includes a high-frequency transformer and a series inductor Lk. The two ends of the primary side of the high-frequency transformer are connected between points A and B of the high-voltage side full-bridge circuit. One end of the secondary side of the high-frequency transformer is connected in series with the inductor Lk and then connected to the midpoint D of the low-voltage side full-bridge circuit. The other end of the secondary side of the high-frequency transformer is connected to the other midpoint E of the low-voltage side full-bridge circuit.

5. The isolated DC-DC converter with wide voltage regulation range and low current ripple according to claim 4, characterized in that, Capacitors C3 and C4 are connected in series and then in parallel across the DC side of the low-voltage half-bridge circuit and the low-voltage full-bridge circuit.

6. The isolated DC-DC converter with wide voltage regulation range and low current ripple according to claim 4, characterized in that, The drains of switching devices S1 and S3 are connected together to form the positive DC-side terminal of the low-voltage side full-bridge circuit, and the sources of switching devices S2 and S4 are connected together to form the negative DC-side terminal of the low-voltage side full-bridge circuit. The negative DC-side terminal of the low-voltage side full-bridge circuit is connected to the negative terminal of the battery port. Points D and E of the low-voltage side full-bridge circuit are respectively connected to one end of inductors L1 and L2 in the interleaved parallel inductors. The low-voltage side full-bridge circuit, together with the first high-frequency isolated energy channel and the high-voltage side full-bridge circuit, constitute a dual active bridge DC-DC converter topology.

7. The control method for an isolated DC-DC converter with a wide voltage regulation range and low current ripple as described in any one of claims 1 to 6, characterized in that, include: High-voltage side split capacitors filter out high-frequency current components flowing through the high-voltage port; The upper and lower switching devices of the two half-bridges in the high-voltage side full-bridge circuit are complementary and conduct with a 50% duty cycle. There is an adjustable phase shift angle between the two half-bridges, which generates an adjustable high-frequency AC voltage, thereby controlling the power flowing through the first high-frequency isolation energy channel. By adjusting the phase shift angle of the high-voltage side full-bridge circuit and the low-voltage side full-bridge circuit, the voltage is adjusted, thereby controlling the current and energy flowing through the first high-frequency isolation energy channel, and finally realizing the power transfer between the high-voltage port and the battery port. The low-voltage side half-bridge circuit and the high-voltage side full-bridge circuit operate synchronously, so that the voltage on the resonant cavity of the second high-frequency isolation energy channel is a two-level high-frequency AC square wave voltage. The low-voltage side split capacitor filters out the high-frequency current component on the low-voltage DC side, providing a stable low-voltage DC side voltage; The driving signals of the two half-bridges in the low-voltage side full-bridge circuit are phase-shifted by 180 degrees to generate a positive and negative balanced high-frequency AC voltage; by adjusting the phase of this high-frequency AC voltage, the energy flowing through the first high-frequency isolation energy channel can be freely controlled. The turns ratio adjusts the battery port voltage and the low-voltage side DC side voltage to adapt to a wide range of battery voltage variations; The ripples of the current in the interleaved parallel inductors cancel each other out.

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