Power conversion device based on partial power conversion and control method thereof

Abstract

The invention discloses a power conversion device based on partial power conversion and a control method thereof, and belongs to the technical field of switching converters. The output end of the first voltage input unit is electrically connected with the input end of the switching tube unit, the input end of the isolated DCDC conversion unit and the input end of the LLC resonant synchronous rectification module, so that the power conversion device can be switched on and off under different input voltage conditions. Whether the isolated DCDC conversion unit works or not is controlled through the switching tube unit, it is ensured that the voltage entering the LLC resonance synchronous rectification module is within the preset LLC voltage regulation range of the LLC resonance synchronous rectification module, and voltage regulation loss caused by the fact that a voltage regulation stage needs to completely convert the voltage input into the power conversion device in the prior art is avoided; the wide voltage gain and the high operation efficiency of the power supply conversion device are kept at the same time, and the operation efficiency of the power supply conversion device in the wide voltage gain is improved.

Description

Technical Field

[0001] This invention belongs to the field of switching converter technology, and particularly relates to a power conversion device and its control method based on partial power conversion. Background Technology

[0002] In current power conversion, the LLC resonant converter is a common solution. It is a high-efficiency power electronic conversion device based on the resonant principle, primarily used for DC-DC or AC-DC energy conversion. By using soft switching to control the frequency of the LLC resonant converter, zero-voltage switching on the primary side and zero-current switching on the secondary side can be achieved. To obtain a wider voltage regulation range, i.e., to achieve wide voltage gain, a larger frequency regulation range is required. However, the relationship between the switching frequency and the resonant frequency can lead to significant circulating current losses in the LLC resonant converter or make it difficult to achieve wide voltage gain under heavy loads.

[0003] To achieve a wide voltage gain in LLC resonant converters, a common approach is to add a voltage regulation stage before the converter. This stage pre-regulates the voltage at the input LLC resonant transformer. Typically, this stage uses interleaved parallel boost circuits or totem-pole circuits. While these two approaches improve the efficiency and achieve a wide voltage gain, both circuits are full voltage regulators, meaning they regulate the entire input voltage, resulting in significant regulation losses. The interleaved parallel boost circuit always has a voltage drop across one inductor and three power semiconductors, with two of these semiconductors operating at high frequency, leading to further regulation losses. The totem-pole circuit also has a voltage drop across two power semiconductors and one inductor, heavily relying on related components to address its reverse recovery problem. These issues result in insufficient voltage regulation capability of the current voltage regulation stage for the input LLC resonant transformer. Although a wide voltage gain can be achieved, it's difficult to guarantee the overall efficiency of the LLC resonant converter under large voltage variations, making it challenging for current power conversion devices to simultaneously maintain a wide voltage gain and high operating efficiency. Therefore, there is an urgent need for a power conversion device and its control method based on partial power conversion to overcome the shortcomings of existing technologies. Summary of the Invention

[0004] The present invention aims to provide a power conversion device and its control method based on partial power conversion, which realizes that the power conversion device can maintain wide voltage gain and high operating efficiency at the same time, thereby improving the operating efficiency of the power conversion device at wide voltage gain.

[0005] To address the aforementioned technical problems, embodiments of the present invention provide a power conversion device based on partial power conversion, comprising: a partial power conversion module and an LLC resonant synchronous rectification module; the partial power conversion module includes: a first voltage input unit, an isolated DC-DC conversion unit, and a switching transistor unit;

[0006] The positive output terminal of the first voltage input unit is electrically connected to the input terminal of the switching transistor unit;

[0007] The positive output terminal of the first voltage input unit is electrically connected to the positive input terminal of the isolated DC-DC converter unit;

[0008] The negative output terminal of the first voltage input unit is electrically connected to the negative input terminal of the isolated DC-DC converter unit.

[0009] The negative output terminal of the first voltage input unit is electrically connected to the negative input terminal of the LLC resonant synchronous rectifier module.

[0010] The positive output terminal of the isolated DC-DC converter unit is electrically connected to the output terminal of the switching transistor unit;

[0011] The negative output terminal of the isolated DC-DC converter unit is electrically connected to the input terminal of the switching transistor unit;

[0012] The output terminal of the switching transistor unit is electrically connected to the positive input terminal of the LLC resonant synchronous rectifier module;

[0013] The input terminal of the first voltage input unit serves as the voltage input terminal of the power conversion device;

[0014] The output of the LLC resonant synchronous rectifier module serves as the voltage output of the power conversion device.

[0015] It is understood that, compared to existing technologies, this invention, by setting up a partial power conversion module and an LLC resonant synchronous rectification module, wherein the partial power conversion module includes a first voltage input unit, an isolated DC-DC converter unit, and a switching transistor unit, and by electrically connecting the output terminal of the first voltage input unit to the input terminals of the switching transistor unit, the isolated DC-DC converter unit, and the LLC resonant synchronous rectification module respectively, allows the power conversion device to control whether the isolated DC-DC converter unit operates under different input voltage conditions through the switching transistor unit. This ensures that the voltage entering the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range of the LLC resonant synchronous rectification module, avoiding the voltage regulation loss caused by the voltage regulation stage in existing technologies needing to completely convert the voltage of the input power conversion device. This achieves the power conversion device maintaining both wide voltage gain and high operating efficiency, improving the operating efficiency of the power conversion device under wide voltage gain.

[0016] When the real-time input voltage of the power conversion device is within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the isolated DC-DC converter unit is stopped by the switching transistor unit. The real-time input voltage can directly enter the LLC resonant synchronous rectifier module through the switching transistor unit, reducing voltage regulation losses and improving the operating efficiency of the power conversion. When the real-time input voltage of the power conversion device is not within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the isolated DC-DC converter unit is started by the switching transistor unit. This allows the isolated DC-DC converter unit to perform power conversion on the real-time input voltage, ensuring that the voltage entering the LLC resonant synchronous rectifier module remains within the preset LLC voltage regulation range.

[0017] As a preferred embodiment, the switching unit includes: a first MOSFET;

[0018] The source of the first MOSFET serves as the input terminal of the switching transistor unit, and it is electrically connected to the positive output terminal of the first voltage input unit.

[0019] The source of the first MOSFET is also electrically connected to the negative output terminal of the isolated DC-DC converter unit;

[0020] The drain of the first MOS transistor serves as the output terminal of the switching transistor unit, and it is electrically connected to the positive output terminal of the isolated DC-DC converter unit.

[0021] The drain of the first MOSFET is electrically connected to the positive input terminal of the LLC resonant synchronous rectifier module.

[0022] This preferred solution, by including a first MOSFET in the switching unit, can control the operation of the isolated DC-DC converter unit, ensuring that the voltage entering the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range of the LLC resonant synchronous rectification module, thereby improving the voltage gain range of the power conversion device. The first MOSFET not only avoids the high voltage regulation loss of the interleaved parallel Boost circuit but also circumvents the reverse recovery problem of the totem-pole circuit, thus improving the operating efficiency of the power conversion device. This achieves the simultaneous maintenance of wide voltage gain and high operating efficiency, improving the operating efficiency of the power conversion device over a wide voltage gain range.

[0023] As a preferred embodiment, the isolated DC-DC converter unit includes: a primary-side input control subunit, an isolation subunit, a rectifier subunit, and a filter subunit;

[0024] The positive input terminal of the primary-side input control subunit serves as the positive input terminal of the isolated DC-DC converter unit, and is electrically connected to the positive output terminal of the first voltage input unit.

[0025] The negative input terminal of the primary-side input control subunit serves as the negative input terminal of the isolated DC-DC converter unit, and is electrically connected to the negative output terminal of the first voltage input unit.

[0026] The positive input terminal of the isolation subunit is electrically connected to the positive output terminal of the primary-side input control subunit;

[0027] The negative input terminal of the isolation subunit is electrically connected to the negative output terminal of the primary input control subunit;

[0028] The positive output terminal of the isolation subunit is electrically connected to the positive input terminal of the rectifier subunit;

[0029] The negative output terminal of the isolation subunit is electrically connected to the negative input terminal of the rectifier subunit;

[0030] The neutral point output of the isolation subunit is electrically connected to the negative input of the filter subunit;

[0031] The output terminal of the rectifier subunit is electrically connected to the positive input terminal of the filter subunit;

[0032] The positive output terminal of the filter subunit serves as the positive output terminal of the isolated DC-DC converter unit, and it is electrically connected to the drain of the first MOS transistor.

[0033] The negative output terminal of the filter subunit serves as the negative output terminal of the isolated DC-DC converter unit, and it is electrically connected to the source of the first MOS transistor.

[0034] This preferred solution sets up an isolated DC-DC converter unit including a primary-side input control subunit, an isolation subunit, a rectifier subunit, and a filter subunit. The primary-side input control subunit receives the voltage from the power conversion device and performs preliminary processing. The isolation subunit provides electrical isolation, ensuring the safety of the isolated DC-DC converter unit during power conversion. Through the coordinated operation of the rectifier and filter subunits, rectification and smoothing are achieved, enabling the isolated DC-DC converter unit to output a stable voltage to the LLC resonant synchronous rectifier module. This improves the operating efficiency and wide voltage gain of the power conversion device when the real-time input voltage is not within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module.

[0035] As a preferred embodiment, the primary-side input control subunit includes: a first switch, a second switch, a first capacitor, and a second capacitor;

[0036] The source of the first switching transistor is electrically connected to the drain of the second switching transistor;

[0037] The second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor.

[0038] The first terminal of the first capacitor is electrically connected to the drain of the first switching transistor;

[0039] The second terminal of the second capacitor is electrically connected to the source of the second switching transistor;

[0040] The drain of the first switching transistor serves as the positive input terminal of the primary-side input control subunit, and is electrically connected to the positive output terminal of the first voltage input unit.

[0041] The first terminal of the first capacitor serves as the positive input terminal of the primary-side input control subunit, and is electrically connected to the positive output terminal of the first voltage input unit.

[0042] The source of the second switching transistor serves as the negative input terminal of the primary-side input control subunit, and is electrically connected to the negative output terminal of the first voltage input unit.

[0043] The second terminal of the second capacitor serves as the negative input terminal of the primary-side input control subunit, and is electrically connected to the negative output terminal of the first voltage input unit.

[0044] The source of the first switching transistor serves as the positive output terminal of the primary-side input control subunit, and is electrically connected to the positive input terminal of the isolation subunit.

[0045] The second terminal of the first capacitor serves as the negative output terminal of the primary-side input control subunit, and is electrically connected to the negative input terminal of the isolation subunit.

[0046] This preferred solution, through the connection between the first switch, the second switch, the first capacitor, and the second capacitor, uses the first and second capacitors to form a midpoint voltage divider, ensuring that the voltage across the first and second switches is half the input voltage of the voltage conversion device. This reduces the conduction losses of the first and second switches, thereby lowering the voltage regulation losses of the power conversion device. Furthermore, the on / off control of the first and second switches enables real-time adjustment of the input voltage of the power conversion device, and the voltage buffering mechanism of the first and second capacitors enables soft switching, significantly reducing high-frequency switching losses and improving the operating efficiency of the isolated DC-DC converter unit, thus enhancing the operating efficiency of the power conversion device over a wide voltage gain range.

[0047] As a preferred embodiment, the rectifier subunit includes: a first diode and a second diode;

[0048] The positive terminal of the first diode serves as the positive input terminal of the rectifier sub-unit, and it is electrically connected to the positive output terminal of the isolation sub-unit.

[0049] The positive terminal of the second diode serves as the negative input terminal of the rectifier subunit, and it is electrically connected to the negative output terminal of the isolation subunit.

[0050] The negative terminal of the second diode is electrically connected to the negative terminal of the first diode;

[0051] The negative terminal of the first diode serves as the output terminal of the rectifier subunit, and it is electrically connected to the positive input terminal of the filter subunit.

[0052] This preferred solution uses a rectifier sub-unit composed of a first diode and a second diode. By using the parallel design of the first diode and the second diode, the reverse recovery problem of the traditional single diode is avoided. This reduces the stress on a single diode, effectively suppresses the voltage fluctuation of the isolated DC-DC converter unit, and improves the quality and stability of the output voltage of the isolated DC-DC converter unit. As a result, the operating quality of the power conversion device is improved over a wide voltage gain range.

[0053] As a preferred embodiment, the filter subunit includes: a fourth inductor and a third capacitor;

[0054] The second terminal of the fourth inductor is electrically connected to the first terminal of the third capacitor;

[0055] The first end of the fourth inductor serves as the positive input terminal of the filter sub-unit, and it is electrically connected to the negative terminal of the first diode.

[0056] The second terminal of the third capacitor serves as the negative input terminal of the filter subunit, and it is electrically connected to the neutral point output terminal of the isolation subunit.

[0057] The first terminal of the third capacitor serves as the positive output terminal of the filter subunit, and it is electrically connected to the drain of the first MOS transistor.

[0058] The second terminal of the third capacitor also serves as the negative output terminal of the filter subunit, and it is electrically connected to the source of the first MOS transistor.

[0059] This preferred solution uses a fourth inductor and a third capacitor to form a filter subunit, which can effectively suppress high-frequency noise, ensure the stability and quality of the voltage output of the isolated DC-DC converter unit, reduce losses caused by voltage fluctuations, and improve the operating efficiency of the power conversion device under wide voltage gain.

[0060] As a preferred embodiment, the LLC resonant synchronous rectification module includes: a second voltage input unit, an LLC resonant primary-side switching unit, an LLC resonant primary-side input unit, an LLC resonant secondary-side output unit, a synchronous rectification unit, and a filtering unit;

[0061] The positive output terminal of the second voltage input unit is electrically connected to the positive input terminal of the LLC resonant primary-side switching unit;

[0062] The negative output terminal of the second voltage input unit is electrically connected to the negative input terminal of the LLC resonant primary-side switching unit.

[0063] The positive output terminal of the LLC resonant primary-side switching unit is electrically connected to the positive input terminal of the LLC resonant primary-side input unit.

[0064] The negative output terminal of the LLC resonant primary-side switching unit is electrically connected to the negative input terminal of the LLC resonant primary-side input unit.

[0065] The output terminal of the primary input unit of the LLC resonant is coupled to the input terminal of the secondary output unit of the LLC resonant.

[0066] The positive output terminal of the LLC resonant secondary output unit is electrically connected to the positive input terminal of the synchronous rectification unit.

[0067] The negative output terminal of the LLC resonant secondary output unit is electrically connected to the negative input terminal of the synchronous rectification unit.

[0068] The neutral point output terminal of the LLC resonant secondary output unit is electrically connected to the positive input terminal of the filter unit.

[0069] The output terminal of the synchronous rectification unit is electrically connected to the negative input terminal of the filter unit;

[0070] The positive input terminal of the second voltage input unit serves as the positive input terminal of the LLC resonant synchronous rectification module, and it is electrically connected to the drain of the first MOS transistor.

[0071] The negative input terminal of the second voltage input unit serves as the negative input terminal of the LLC resonant synchronous rectifier module, and is electrically connected to the negative output terminal of the first voltage input unit.

[0072] The output of the filter unit serves as the output of the LLC resonant synchronous rectifier module.

[0073] This preferred solution, through the design of a second voltage input unit, an LLC resonant primary-side switching unit, an LLC resonant primary-side input unit, an LLC resonant secondary-side output unit, a synchronous rectification unit, and a filtering unit, can achieve efficient voltage conversion. The synchronous rectification unit can reduce the conduction loss of the LLC resonant synchronous rectification module, and the filtering unit can improve the output voltage quality of the LLC resonant synchronous rectification module. This allows the power conversion device to maintain both wide voltage gain and high operating efficiency, thereby improving the operating efficiency of the power conversion device at a wide voltage gain.

[0074] Accordingly, embodiments of the present invention provide a control method for a power conversion device based on partial power conversion, applied to the power conversion device based on partial power conversion as described above, including the following steps:

[0075] The real-time input voltage and real-time output power of the power conversion device are obtained, and the operating state of the isolated DC-DC converter unit is determined based on the real-time input voltage and real-time output power.

[0076] When the isolated DC-DC converter unit is in the off state, the first MOSFET is turned on, so that the voltage output by the first voltage input unit is input to the LLC resonant synchronous rectifier module through the first MOSFET, thereby making the voltage input to the LLC resonant synchronous rectifier module within the preset LLC voltage regulation range.

[0077] When the isolated DC-DC converter unit is in normal operating state, the first MOSFET is turned off, allowing the isolated DC-DC converter unit to perform power conversion on the voltage output from the first voltage input unit, thereby ensuring that the voltage of the input LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range.

[0078] Understandably, compared to existing technologies, this invention determines the operating state of the isolated DC-DC converter unit based on the real-time input voltage and real-time output power of the power conversion device. When the isolated DC-DC converter unit is in a stopped operating state, the first MOSFET is turned on, allowing the real-time input voltage to directly enter the LLC resonant synchronous rectification module, reducing voltage regulation losses and improving the operating efficiency of the power conversion. When the isolated DC-DC converter unit is in a normal operating state, the first MOSFET is turned off, enabling the isolated DC-DC converter unit to perform power conversion on the voltage output from the first voltage input unit. The voltage input to the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range, avoiding the voltage regulation losses caused by the voltage regulation stage needing to completely convert the input voltage of the power conversion device in existing technologies. This achieves both wide voltage gain and high operating efficiency for the power conversion device, improving its operating efficiency over a wide voltage gain range.

[0079] As a preferred embodiment, the operating state of the isolated DC-DC converter unit is determined based on the real-time input voltage and real-time output power, including:

[0080] Based on the real-time input voltage and real-time output power, plot the first efficiency curve of the partial power conversion module and the second efficiency curve of the LLC resonant synchronous rectifier module respectively.

[0081] Based on the preset hysteresis factor and preset judgment formula, combined with the first efficiency curve and the second efficiency curve, it is determined whether the real-time input voltage is within the preset LLC voltage regulation range.

[0082] When the real-time input voltage is within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the stopped working state;

[0083] When the real-time input voltage is not within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the normal working state.

[0084] This preferred solution improves the accuracy of determining whether the real-time input voltage is within the preset LLC voltage regulation range by plotting the first efficiency curve of the partial power conversion module and the second efficiency curve of the LLC resonant synchronous rectification module, and then combining the preset hysteresis factor and preset judgment formula, thereby improving the operational stability and quality of the power conversion device.

[0085] As a preferred embodiment, when the isolated DC-DC converter unit is in normal operating condition, the first MOSFET is turned off, allowing the isolated DC-DC converter unit to perform power conversion on the voltage output from the first voltage input unit, thereby ensuring that the voltage of the input LLC resonant synchronous rectifier module is within a preset LLC voltage regulation range, including:

[0086] When the power conversion module is in normal working state, the first MOSFET is turned off.

[0087] In each switching cycle of the power conversion device, the first and second switching transistors are controlled according to the preset switching control sequence and the half-cycle duty cycle of the switching cycle, so that the isolated DC-DC converter unit performs power conversion on the voltage output by the first voltage input unit, thereby ensuring that the voltage of the input LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range.

[0088] This preferred solution, by turning off the first MOSFET and regulating the first and second switching transistors, enables the isolated DC-DC converter unit to convert the voltage output from the first voltage input unit into power, thereby ensuring that the voltage of the input LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range, and ensuring the stable and efficient operation of the power conversion device. Attached Figure Description

[0089] Figure 1 A schematic diagram of a power conversion device based on partial power conversion provided in an embodiment of the present invention;

[0090] Figure 2 A schematic diagram of a power conversion device based on partial power conversion provided in an embodiment of the present invention;

[0091] Figure 3 This is a schematic diagram of the structure of an isolated DC-DC converter unit provided in an embodiment of the present invention;

[0092] Figure 4 This is a topology diagram illustrating the normal operation of a power conversion device according to an embodiment of the present invention;

[0093] Figure 5 This is a topology diagram illustrating a power conversion device malfunction according to an embodiment of the present invention.

[0094] Figure 6 This is a schematic diagram of the operation of a partial power conversion module in the first control state provided in an embodiment of the present invention;

[0095] Figure 7 This is a schematic diagram of the operation of the partial power conversion module in the third control state provided in an embodiment of the present invention;

[0096] Figure 8 A schematic diagram of the operation of a partial power conversion module in the second and fourth control states provided in an embodiment of the present invention;

[0097] Figure 9 A waveform diagram of a power conversion module under different control states provided in an embodiment of the present invention;

[0098] Figure 10 This is a schematic diagram illustrating the steps of a control method for a power conversion device based on partial power conversion, provided in an embodiment of the present invention. Detailed Implementation

[0099] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0100] Example 1

[0101] Please refer to Figure 1 , Figure 1 A schematic diagram of a power conversion device based on partial power conversion provided in an embodiment of the present invention includes: a partial power conversion module 1 and an LLC resonant synchronous rectification module 2; the partial power conversion module 1 includes: a first voltage input unit 11, an isolated DC-DC conversion unit 12 and a switching transistor unit 13;

[0102] The positive output terminal of the first voltage input unit 11 is electrically connected to the input terminal of the switching transistor unit 13;

[0103] The positive output terminal of the first voltage input unit 11 is electrically connected to the positive input terminal of the isolated DC-DC converter unit 12;

[0104] The negative output terminal of the first voltage input unit 11 is electrically connected to the negative input terminal of the isolated DC-DC converter unit 12;

[0105] The negative output terminal of the first voltage input unit 11 is electrically connected to the negative input terminal of the LLC resonant synchronous rectifier module 2.

[0106] The positive output terminal of the isolated DC-DC converter unit 12 is electrically connected to the output terminal of the switching transistor unit 13;

[0107] The negative output terminal of the isolated DC-DC converter unit 12 is electrically connected to the input terminal of the switching transistor unit 13;

[0108] The output terminal of the switching transistor unit 13 is electrically connected to the positive input terminal of the LLC resonant synchronous rectifier module 2;

[0109] The input terminal of the first voltage input unit 11 serves as the voltage input terminal of the power conversion device;

[0110] The output terminal of LLC resonant synchronous rectifier module 2 serves as the voltage output terminal of the power conversion device.

[0111] Please refer to Figure 2 , Figure 2 This is a schematic diagram of a power conversion device based on partial power conversion, provided in an embodiment of the present invention.

[0112] In this embodiment, as Figure 2 As shown, the switching transistor unit 13 includes: a first MOSFET S1;

[0113] The source of the first MOSFET S1 serves as the input terminal of the switching transistor unit 13, and is electrically connected to the positive output terminal of the first voltage input unit 11.

[0114] The source of the first MOS transistor S1 is also electrically connected to the negative output terminal of the isolated DC-DC converter unit 12.

[0115] The drain of the first MOS transistor S1 serves as the output terminal of the switching transistor unit 13, and is electrically connected to the positive output terminal of the isolated DC-DC converter unit 12.

[0116] The drain of the first MOSFET S1 is electrically connected to the positive input terminal of the LLC resonant synchronous rectifier module 2.

[0117] This embodiment, by including a first MOSFET in the switching unit, can control whether the isolated DC-DC converter unit operates, ensuring that the voltage entering the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range of the LLC resonant synchronous rectification module, thereby improving the voltage gain range of the power conversion device. The first MOSFET not only avoids the high voltage regulation loss of the interleaved parallel Boost circuit but also avoids the reverse recovery problem of the totem-pole circuit, thus improving the operating efficiency of the power conversion device. This achieves the power conversion device maintaining both wide voltage gain and high operating efficiency, improving the operating efficiency of the power conversion device over a wide voltage gain range.

[0118] In this embodiment, please refer to Figure 3, Figure 3 This is a schematic diagram of the structure of an isolated DC-DC converter unit provided in an embodiment of the present invention; the isolated DC-DC converter unit 12 includes: a primary-side input control subunit 121, an isolation subunit 122, a rectifier subunit 123, and a filter subunit 124;

[0119] The positive input terminal of the primary-side input control subunit 121 serves as the positive input terminal of the isolated DC-DC converter unit 12, and is electrically connected to the positive output terminal of the first voltage input unit 11.

[0120] The negative input terminal of the primary-side input control subunit 121 serves as the negative input terminal of the isolated DC-DC converter unit 12, and is electrically connected to the negative output terminal of the first voltage input unit 11.

[0121] The positive input terminal of the isolation subunit 122 is electrically connected to the positive output terminal of the primary input control subunit 121;

[0122] The negative input terminal of the isolation subunit 122 is electrically connected to the negative output terminal of the primary input control subunit 121;

[0123] The positive output terminal of the isolation subunit 122 is electrically connected to the positive input terminal of the rectifier subunit 123;

[0124] The negative output terminal of the isolation subunit 122 is electrically connected to the negative input terminal of the rectifier subunit 123;

[0125] The neutral point output terminal of the isolation subunit 122 is electrically connected to the negative input terminal of the filter subunit 124;

[0126] The output terminal of the rectifier subunit 123 is electrically connected to the positive input terminal of the filter subunit 124;

[0127] The positive output terminal of the filter subunit 124 serves as the positive output terminal of the isolated DC-DC converter unit 12, and is electrically connected to the drain of the first MOS transistor S1.

[0128] The negative output terminal of the filter subunit 124 serves as the negative output terminal of the isolated DC-DC converter unit 12, and is electrically connected to the source of the first MOS transistor S1.

[0129] This embodiment sets up an isolated DC-DC converter unit including a primary-side input control subunit, an isolation subunit, a rectification subunit, and a filtering subunit. The primary-side input control subunit receives the voltage from the input power conversion device and performs preliminary processing. The isolation subunit provides electrical isolation, ensuring the safety of the isolated DC-DC converter unit during power conversion. Through the coordinated operation of the rectification and filtering subunits, rectification and smoothing are achieved, enabling the isolated DC-DC converter unit to output a stable voltage to the LLC resonant synchronous rectifier module. This improves the operating efficiency and wide voltage gain of the power conversion device when the real-time input voltage is not within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module.

[0130] In this embodiment, as Figure 2 As shown, the primary-side input control subunit 121 includes: a first switch Q1, a second switch Q2, a first capacitor C1, and a second capacitor C2;

[0131] The source of the first switching transistor Q1 is electrically connected to the drain of the second switching transistor Q2;

[0132] The second terminal of the first capacitor C1 is electrically connected to the first terminal of the second capacitor C2;

[0133] The first terminal of the first capacitor C1 is electrically connected to the drain of the first switching transistor Q1;

[0134] The second terminal of the second capacitor C2 is electrically connected to the source of the second switching transistor Q2;

[0135] The drain of the first switching transistor Q1 serves as the positive input terminal of the primary-side input control subunit 121, and is electrically connected to the positive output terminal of the first voltage input unit 11.

[0136] The first terminal of the first capacitor C1 serves as the positive input terminal of the primary-side input control subunit 121, and is electrically connected to the positive output terminal of the first voltage input unit 11.

[0137] The source of the second switch Q2 serves as the negative input terminal of the primary-side input control subunit 121, and is electrically connected to the negative output terminal of the first voltage input unit 11.

[0138] The second terminal of the second capacitor C2 serves as the negative input terminal of the primary-side input control subunit 121, and is electrically connected to the negative output terminal of the first voltage input unit 11.

[0139] The source of the first switching transistor Q1 serves as the positive output terminal of the primary-side input control subunit 121, and is electrically connected to the positive input terminal of the isolation subunit 122.

[0140] The second terminal of the first capacitor C1 serves as the negative output terminal of the primary-side input control subunit 121, and is electrically connected to the negative input terminal of the isolation subunit 122.

[0141] This embodiment utilizes the connection between the first and second switching transistors, the first capacitor, and the second capacitor to form a midpoint voltage divider. This ensures that the first and second switching transistors withstand half the input voltage of the voltage conversion device, reducing their conduction losses and thus lowering the voltage regulation losses of the power conversion device. Furthermore, the on / off control of the first and second switching transistors enables real-time adjustment of the power conversion device's input voltage. The voltage buffering mechanism of the first and second capacitors facilitates soft switching, significantly reducing high-frequency switching losses and improving the operating efficiency of the isolated DC-DC converter unit. Ultimately, this enhances the operating efficiency of the power conversion device across a wide voltage gain range.

[0142] In this embodiment, the rectifier sub-unit 123 includes: a first diode D1 and a second diode D2;

[0143] The positive terminal of the first diode D1 serves as the positive input terminal of the rectifier subunit 123, and is electrically connected to the positive output terminal of the isolation subunit 122.

[0144] The positive terminal of the second diode D2 serves as the negative input terminal of the rectifier subunit 123, and it is electrically connected to the negative output terminal of the isolation subunit 122.

[0145] The negative terminal of the second diode D2 is electrically connected to the negative terminal of the first diode D1;

[0146] The negative terminal of the first diode D1 serves as the output terminal of the rectifier subunit 123, and it is electrically connected to the positive input terminal of the filter subunit 124.

[0147] This embodiment uses a rectifier sub-unit composed of a first diode and a second diode. By using the parallel design of the first diode and the second diode, the reverse recovery problem of the traditional single diode is avoided. This reduces the stress on a single diode, effectively suppresses the voltage fluctuation of the isolated DC-DC converter unit, and improves the quality and stability of the output voltage of the isolated DC-DC converter unit. As a result, the operating quality of the power conversion device is improved over a wide voltage gain range.

[0148] In this embodiment, the filter subunit 124 includes: a fourth inductor L4 and a third capacitor C3;

[0149] The second terminal of the fourth inductor L4 is electrically connected to the first terminal of the third capacitor C3;

[0150] The first end of the fourth inductor L4 serves as the positive input terminal of the filter subunit 124, and it is electrically connected to the negative terminal of the first diode D1.

[0151] The second terminal of the third capacitor C3 serves as the negative input terminal of the filter subunit 124, and it is electrically connected to the neutral point output terminal of the isolation subunit 122.

[0152] The first terminal of the third capacitor C3 serves as the positive output terminal of the filter subunit 124, and it is electrically connected to the drain of the first MOS transistor S1.

[0153] The second terminal of the third capacitor C3 also serves as the negative output terminal of the filter subunit 124, which is electrically connected to the source of the first MOS transistor S1.

[0154] This embodiment uses a fourth inductor and a third capacitor to form a filter subunit, which can effectively suppress high-frequency noise, ensure the stability and quality of the voltage output by the isolated DC-DC converter unit, reduce losses caused by voltage fluctuations, and improve the operating efficiency of the power conversion device over a wide voltage gain range.

[0155] In this embodiment, as Figure 2 As shown, the isolation subunit 122 includes: a first inductor L1, a second inductor L2, and a third inductor L3;

[0156] The first inductor L1 is coupled to the second inductor L2;

[0157] The first inductor L1 is coupled to the third inductor L3;

[0158] The second terminal of the second inductor L2 is electrically connected to the first terminal of the third inductor L3;

[0159] The first end of the first inductor L1 serves as the positive input terminal of the isolation subunit 122, and is electrically connected to the source of the first switching transistor Q1.

[0160] The second terminal of the first inductor L1 serves as the negative input terminal of the isolation subunit 122, and is electrically connected to the second terminal of the first capacitor C1.

[0161] The first end of the second inductor L2 serves as the positive output terminal of the isolation subunit 122, and it is electrically connected to the positive terminal of the first diode D1.

[0162] The second terminal of the third inductor L3 serves as the negative output terminal of the isolation subunit 122, and is electrically connected to the positive terminal of the second diode D2.

[0163] The second terminal of the second inductor L2 serves as the neutral point output terminal of the isolation subunit 122, and is electrically connected to the second terminal of the third capacitor C3.

[0164] In this embodiment, as Figure 1As shown, the LLC resonant synchronous rectification module 2 includes: a second voltage input unit 21, an LLC resonant primary-side switching unit 22, an LLC resonant primary-side input unit 23, an LLC resonant secondary-side output unit 24, a synchronous rectification unit 25, and a filtering unit 26;

[0165] The positive output terminal of the second voltage input unit 21 is electrically connected to the positive input terminal of the LLC resonant primary-side switching unit 22;

[0166] The negative output terminal of the second voltage input unit 21 is electrically connected to the negative input terminal of the LLC resonant primary-side switching unit 22.

[0167] The positive output terminal of LLC resonant primary-side switching unit 22 is electrically connected to the positive input terminal of LLC resonant primary-side input unit 23.

[0168] The negative output terminal of LLC resonant primary-side switching unit 22 is electrically connected to the negative input terminal of LLC resonant primary-side input unit 23.

[0169] The output terminal of the LLC resonant primary-side input unit 23 is coupled to the input terminal of the LLC resonant secondary-side output unit 24.

[0170] The positive output terminal of the LLC resonant secondary output unit 24 is electrically connected to the positive input terminal of the synchronous rectification unit 25.

[0171] The negative output terminal of the LLC resonant secondary output unit 24 is electrically connected to the negative input terminal of the synchronous rectification unit 25.

[0172] The neutral point output terminal of the LLC resonant secondary output unit 24 is electrically connected to the positive input terminal of the filter unit 26.

[0173] The output terminal of the synchronous rectification unit 25 is electrically connected to the negative input terminal of the filter unit 26;

[0174] The positive input terminal of the second voltage input unit 21 serves as the positive input terminal of the LLC resonant synchronous rectification module 2, and is electrically connected to the drain of the first MOS transistor S1.

[0175] The negative input terminal of the second voltage input unit 21 serves as the negative input terminal of the LLC resonant synchronous rectifier module 2, and is electrically connected to the negative output terminal of the first voltage input unit 11.

[0176] The output of the filter unit 26 serves as the output of the LLC resonant synchronous rectifier module 2.

[0177] This embodiment, through the design of a second voltage input unit, an LLC resonant primary-side switching unit, an LLC resonant primary-side input unit, an LLC resonant secondary-side output unit, a synchronous rectification unit, and a filtering unit, can achieve efficient voltage conversion. The synchronous rectification unit can reduce the conduction loss of the LLC resonant synchronous rectification module, and the filtering unit can improve the output voltage quality of the LLC resonant synchronous rectification module. This allows the power conversion device to maintain both wide voltage gain and high operating efficiency, thereby improving the operating efficiency of the power conversion device over a wide voltage gain range.

[0178] In this embodiment, as Figure 2 As shown, the second voltage input unit 21 includes: a fourth capacitor C4;

[0179] The first terminal of the fourth capacitor C4 serves as the positive input terminal of the second voltage input unit 21, and it is electrically connected to the drain of the first MOSFET S1.

[0180] The second terminal of the fourth capacitor C4 serves as the negative input terminal of the second voltage input unit 21, and is electrically connected to the negative output terminal of the first voltage input unit 11.

[0181] The first terminal of the fourth capacitor C4 serves as the positive output terminal of the second voltage input unit 21, and is electrically connected to the positive input terminal of the LLC resonant primary-side switching unit 22.

[0182] The second terminal of the fourth capacitor C4 serves as the negative output terminal of the second voltage input unit 21, and is electrically connected to the negative input terminal of the LLC resonant primary-side switching unit 22.

[0183] In this embodiment, as Figure 2 As shown, the first voltage input unit 11 includes: an input capacitor Ci;

[0184] The input capacitor Ci serves as the input terminal of the first voltage input unit 11, which is used to receive external voltage.

[0185] The first terminal of the input capacitor Ci serves as the positive output terminal of the first voltage input unit 11, and it is electrically connected to the source of the first MOS transistor S1.

[0186] The first terminal of the input capacitor Ci is electrically connected to the drain of the first switching transistor Q1;

[0187] The first terminal of the input capacitor Ci is electrically connected to the first terminal of the first capacitor C1.

[0188] The second terminal of the input capacitor Ci serves as the negative output terminal of the first voltage input unit 11, and is electrically connected to the second terminal of the fourth capacitor C4.

[0189] The second terminal of the input capacitor Ci is electrically connected to the source of the second switching transistor Q2;

[0190] The second terminal of the input capacitor Ci is electrically connected to the second terminal of the second capacitor C2.

[0191] In this embodiment, as Figure 2 As shown, the LLC resonant primary-side switching unit 22 includes: a third switch Q3, a fourth switch Q4, a fifth switch Q5, and a sixth switch Q6;

[0192] The drain of the third switch Q3 serves as the positive input terminal of the LLC resonant primary-side switch unit 22, and it is electrically connected to the first terminal of the fourth capacitor C4.

[0193] The drain of the fifth switch Q5 serves as the positive input terminal of the LLC resonant primary-side switch unit 22, and is electrically connected to the first terminal of the fourth capacitor C4.

[0194] The source of the fourth switch Q4 serves as the negative input terminal of the LLC resonant primary-side switch unit 22, and it is electrically connected to the second terminal of the fourth capacitor C4.

[0195] The source of the sixth switch Q6 serves as the negative input terminal of the LLC resonant primary-side switch unit 22, and is electrically connected to the second terminal of the fourth capacitor C4.

[0196] The source of the third switch Q3 is electrically connected to the drain of the fourth switch Q4.

[0197] The source of the fifth switch Q5 is electrically connected to the drain of the sixth switch Q6;

[0198] The source of the third switch Q3 serves as the positive output terminal of the LLC resonant primary-side switch unit 22, and is electrically connected to the positive input terminal of the LLC resonant primary-side input unit 23.

[0199] The source of the fifth switch Q5 serves as the negative output terminal of the LLC resonant primary-side switch unit 22, and is electrically connected to the negative input terminal of the LLC resonant primary-side input unit 23.

[0200] In this embodiment, as Figure 2 As shown, the LLC resonant primary-side input unit 23 includes: a ninth inductor L9, a fifth capacitor C5, and a fifth inductor L5;

[0201] The first terminal of the ninth inductor L9 serves as the positive input terminal of the primary side input unit 23 of the LLC resonant circuit, and it is electrically connected to the source of the third switch Q3.

[0202] The first terminal of the fifth capacitor C5 serves as the negative input terminal of the LLC resonant primary-side input unit 23, and it is electrically connected to the source of the fifth switch Q5.

[0203] The second terminal of the ninth inductor L9 is electrically connected to the first terminal of the fifth inductor L5;

[0204] The second terminal of the fifth capacitor C5 is electrically connected to the second terminal of the fifth inductor L5;

[0205] The fifth inductor L5 serves as the output terminal of the LLC resonant primary-side input unit 23, and it is coupled to the input terminal of the LLC resonant secondary-side output unit 24.

[0206] In this embodiment, as Figure 2 As shown, the LLC resonant secondary output unit 24 includes: a sixth inductor L6 and a seventh inductor L7;

[0207] The sixth inductor L6 and the seventh inductor L7 both serve as input terminals of the LLC resonant secondary output unit 24, and they are both coupled to the fifth inductor L5.

[0208] The second terminal of the sixth inductor L6 is electrically connected to the first terminal of the seventh inductor L7;

[0209] The first end of the sixth inductor L6 serves as the positive output terminal of the LLC resonant secondary output unit 24, and is electrically connected to the positive input terminal of the synchronous rectification unit 25.

[0210] The second end of the seventh inductor L7 serves as the negative output terminal of the LLC resonant secondary output unit 24, and is electrically connected to the negative input terminal of the synchronous rectification unit 25.

[0211] The second end of the sixth inductor L6 serves as the neutral point output terminal of the LLC resonant secondary output unit 24, and is electrically connected to the positive input terminal of the filter unit 26.

[0212] In this embodiment, as Figure 2 As shown, the synchronous rectification unit 25 includes: a second MOSFET S2 and a third MOSFET S3;

[0213] The drain of the second MOSFET S2 serves as the positive input terminal of the synchronous rectification unit 25, and it is electrically connected to the first terminal of the sixth inductor L6.

[0214] The drain of the third MOSFET S3 serves as the negative input terminal of the synchronous rectification unit 25, and it is electrically connected to the second terminal of the seventh inductor L7.

[0215] The source of the second MOSFET S2 is electrically connected to the source of the third MOSFET S3.

[0216] The source of the third MOSFET S3 serves as the output terminal of the synchronous rectification unit 25, and it is electrically connected to the negative input terminal of the filter unit 26.

[0217] In this embodiment, as Figure 2 As shown, the filter unit 26 includes: an eighth inductor L8 and an output capacitor Co;

[0218] The first end of the eighth inductor L8 serves as the positive input terminal of the filter unit 26, and it is electrically connected to the second end of the sixth inductor L6.

[0219] The second terminal of the output capacitor Co serves as the negative input terminal of the filter unit 26, and it is electrically connected to the source of the third MOS transistor S3.

[0220] The first terminal of the output capacitor Co is electrically connected to the second terminal of the eighth inductor L8;

[0221] The output capacitor Co serves as the output terminal of the filter unit 26.

[0222] Based on the connection relationships described above, combined with Figure 2 The working principle of the power conversion device based on partial power conversion according to embodiments of the present invention will be described below:

[0223] First, it is necessary to determine whether the real-time input voltage of the power conversion device is within the preset LLC voltage regulation range of the LLC resonant synchronous rectification module. The specific determination process is as follows: Based on the real-time input voltage vi and output power po of the power conversion device, plot the first efficiency curve of the partial power conversion module, denoted as ηp(po,vi); plot the second efficiency curve of the LLC resonant synchronous rectification module, denoted as ηl(po,vi), where ηp is the efficiency of the partial power conversion module and ηl is the efficiency of the LLC resonant synchronous rectification module; then, determine whether the real-time input voltage is within the preset LLC voltage regulation range based on the preset hysteresis factor and preset judgment formula.

[0224] The preset hysteresis factor is H, which is used to avoid frequent start-stop of some power conversion modules. Specifically, the hysteresis factor H is:

[0225] The preset judgment formula is:

[0226] If the judgment formula is true, then when the real-time input voltage is within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the stopped working state.

[0227] If the judgment formula is not true, then when the real-time input voltage is not within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the normal working state.

[0228] Please refer to Figure 4 , Figure 4 This is a topology diagram of a power conversion device at its normal operating point, provided by an embodiment of the present invention; as shown. Figure 4As shown, when the real-time input voltage of the power conversion device is within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, it is considered that the power conversion device is in normal working point, that is, the working state of the isolated DC-DC converter unit is the stopped working state. At this time, the working topology of the power conversion device is as follows: Figure 4 As shown, by inputting voltage (i.e., real-time input voltage) to the input capacitor Ci, the real-time input voltage is then directly connected to the fourth capacitor C4 through the first MOSFET S1, thus entering the LLC resonant synchronous rectification module 2. At this time, the LLC resonant synchronous rectification module 2 can operate at approximately the rated turns ratio and can operate approximately at a resonant switching frequency with a reduced voltage gain of one. Under all load conditions, it can achieve zero-voltage switching of the primary-side switching devices and zero-current switching of the secondary-side switching devices, enabling the LLC resonant synchronous rectification module 2 to operate with high efficiency. At this time, the voltage Vli of the fourth capacitor C4 is Vli = Vi, where Vi is maintained near the reference voltage Vref.

[0229] Please refer to Figure 5 , Figure 5 This is a topology diagram illustrating an abnormal operating point of a power conversion device according to an embodiment of the present invention. When the real-time input voltage of the power conversion device is not within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the power conversion device is considered to be in an abnormal operating point, i.e., the working state of the isolated DC-DC converter unit is the normal operating state. The operating topology of the power conversion device at this time is as follows: Figure 5 As shown by the red line, the first MOSFET S1 is turned off, and the isolated DC-DC converter unit 12 starts working. In each switching cycle of the power conversion device, the first switch Q1 and the second switch Q2 are alternately turned on according to a preset switching control sequence. The preset switching control sequence is as follows: the first control state is that the first switch Q1 is on and the second switch Q2 is off; the second control state is that the first switch Q1 is off and the second switch Q2 is off; the third control state is that the first switch Q1 is off and the second switch Q2 is on; the fourth control state is that the first switch Q1 is off and the second switch Q2 is off. That is, in each switching cycle, the first switch Q1 and the second switch Q2 are controlled in the order of the first control state, the second control state, the third control state, and the fourth control state. Further, please refer to... Figure 6 , Figure 6 This is a schematic diagram of the operation of a partial power conversion module in the first control state provided in an embodiment of the present invention, as shown below. Figure 6As shown, at this time, the first switch Q1 is turned on and the second switch Q2 is turned off, which is the positive half-cycle mode; the voltage across the input capacitor Ci is Vi, and the voltages across the first capacitor C1 and the second capacitor C2 are both Vi / 2; by turning on the first switch Q1 and turning off the second switch Q2, the primary side of the transformer (i.e., the first inductor L1) bears a voltage of Vi / 2, which is coupled to the secondary side of the transformer (i.e., the second inductor L2 at this time), and then charges the third capacitor C3 through the first diode D1. The third capacitor C3 then inputs the voltage to the LLC resonant synchronous rectifier module; please refer to... Figure 7 , Figure 7 This is a schematic diagram of the operation of the partial power conversion module in the third control state provided in an embodiment of the present invention, as shown below. Figure 7 As shown, at this time, the first switch Q1 is off and the second switch Q2 is on, which is the negative half-cycle mode. The voltage across the input capacitor Ci is Vi, and the voltages across the first capacitor C1 and the second capacitor C2 are both Vi / 2. With the first switch Q1 off and the second switch Q2 on, the primary side of the transformer (i.e., the first inductor L1) experiences a voltage of -Vi / 2. This voltage is coupled to the secondary side of the transformer (i.e., the third inductor L3 at this time), and then charges the third capacitor C3 through the second diode D2. The third capacitor C3 then inputs the voltage to the LLC resonant synchronous rectifier module. Please refer to... Figure 8 , Figure 8 This is a partial power conversion module operation diagram for the second and fourth control states provided in an embodiment of the present invention, as shown below. Figure 8 As shown, since the first switch Q1 and the second switch Q2 are both turned off in the second and fourth control states, it is in freewheeling mode. At this time, the first diode D1 and the second diode D2 provide freewheeling current to the fourth inductor L4. To maintain balance, the current relationship between the first diode D1, the second diode D2, and the fourth inductor L4 is: i D1 =i D2 =0.5*i L4 i D1 i is the current through the first diode D1. D2 i is the current through the second diode D2. L4 This refers to the current in the fourth inductor L4; please refer to... Figure 9 , Figure 9 This is a waveform diagram of a partial power conversion module under different control states provided in an embodiment of the present invention; such as... Figure 9As shown, ① represents the first control state, ② the second control state, ③ the third control state, and ④ the fourth control state. The primary-side voltage refers to the voltage across the first inductor L1, and the secondary-side voltage refers to the voltage output by the rectifier subunit 123 (i.e., the voltage output after rectification by the first diode D1 and the second diode D2). The secondary-side capacitor voltage refers to the voltage across the third capacitor C3. D refers to the duty cycle of the switching cycle, and Ts refers to the half-cycle of the switching cycle. Figure 9 As shown in (a), it is a waveform diagram of the primary voltage (i.e., the voltage across the first inductor L1) under different control states. Figure 9 (b) is a waveform diagram of the current in the fourth inductor L4 under different control states; Figure 9 (c) is a waveform diagram of the voltage output by rectifier subunit 123 (i.e., the voltage output after rectification by the first diode D1 and the second diode D2) under different control states.

[0230] Figure 9 (d) is the current waveform of the first diode D1 under different control states; Figure 9 (e) is the waveform diagram of the secondary capacitor voltage (i.e., the voltage on the third capacitor C3) under different control states; Figure 9 (f) shows the current waveform of the second diode D2 under different control states; the ratio of the duration of the first control state (i.e., state ①) to the sum of the durations of the first control state (i.e., state ①) and the second control state (i.e., state ②) is set to be the same as the ratio of the duration of the third control state (i.e., state ③) to the sum of the durations of the third control state (i.e., state ③) and the fourth control state (i.e., state ④), and both are half-cycle duty cycles D of the switching cycle; at this time, the voltage on the output capacitor Ci is Vi, the voltage on the third capacitor C3 is Vpo, and the turns ratio of the primary side (i.e., the first inductor L1) and the secondary side (i.e., the second inductor L2 or the third inductor L3) is n, and at this time there is At this point, the voltage Vli across the fourth capacitor C4 is Vli = Vpo + Vi = Vref; by adjusting the half-cycle duty cycle D of the switching cycle, it is possible to make Vli = Vpo + Vi = Vref and This ensures that the LLC resonant synchronous rectifier module operates at its rated turns ratio and can operate at a fixed resonant switching frequency with a reduced voltage gain of one, achieving zero-voltage switching on the primary side and zero-current switching on the secondary side under all load conditions.

[0231] This embodiment incorporates a partial power conversion module and an LLC resonant synchronous rectification module. The partial power conversion module includes a first voltage input unit, an isolated DC-DC converter unit, and a switching transistor unit. By electrically connecting the output of the first voltage input unit to the input of the switching transistor unit, the input of the isolated DC-DC converter unit, and the input of the LLC resonant synchronous rectification module, the power conversion device can control the operation of the isolated DC-DC converter unit under different input voltage conditions through the switching transistor unit. This ensures that the voltage entering the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range of the LLC resonant synchronous rectification module. This avoids the voltage regulation losses caused by the voltage regulation stage in the prior art needing to completely convert the voltage of the input power conversion device. It achieves both wide voltage gain and high operating efficiency in the power conversion device, improving its operating efficiency over a wide voltage gain range. When the real-time input voltage of the power conversion device is within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the isolated DC-DC converter unit is stopped by the switching transistor unit. The real-time input voltage can directly enter the LLC resonant synchronous rectifier module through the switching transistor unit, reducing voltage regulation losses and improving the operating efficiency of the power conversion. When the real-time input voltage of the power conversion device is not within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the isolated DC-DC converter unit is started by the switching transistor unit. This allows the isolated DC-DC converter unit to perform power conversion on the real-time input voltage, ensuring that the voltage entering the LLC resonant synchronous rectifier module remains within the preset LLC voltage regulation range.

[0232] Example 2

[0233] Please refer to Figure 10 , Figure 10 This is a schematic diagram of the steps of a control method for a power conversion device based on partial power conversion provided in an embodiment of the present invention. It is applied to a power conversion device based on partial power conversion as described above, and includes steps S201 to S203.

[0234] Step S201: Obtain the real-time input voltage and real-time output power of the power conversion device, and determine the operating state of the isolated DC-DC converter unit based on the real-time input voltage and real-time output power.

[0235] In this embodiment, the operating state of the isolated DC-DC converter unit is determined based on the real-time input voltage and real-time output power, including:

[0236] Based on the real-time input voltage and real-time output power, plot the first efficiency curve of the partial power conversion module and the second efficiency curve of the LLC resonant synchronous rectifier module respectively.

[0237] Based on the preset hysteresis factor and preset judgment formula, combined with the first efficiency curve and the second efficiency curve, it is determined whether the real-time input voltage is within the preset LLC voltage regulation range.

[0238] When the real-time input voltage is within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the stopped working state;

[0239] When the real-time input voltage is not within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the normal working state.

[0240] It should be noted that for details regarding determining the operating state of the isolated DC-DC converter unit based on the real-time input voltage and real-time output power, please refer to the description in Example 1.

[0241] This embodiment improves the accuracy of determining whether the real-time input voltage is within the preset LLC voltage regulation range by plotting the first efficiency curve of the partial power conversion module and the second efficiency curve of the LLC resonant synchronous rectification module, and by combining the preset hysteresis factor and preset judgment formula, thereby improving the operational stability and quality of the power conversion device.

[0242] Step S202: When the isolated DC-DC converter unit is in the off state, the first MOSFET is turned on, so that the voltage output by the first voltage input unit is input to the LLC resonant synchronous rectifier module through the first MOSFET, thereby making the voltage input to the LLC resonant synchronous rectifier module within the preset LLC voltage regulation range.

[0243] It should be noted that for the specific working process of the isolated DC-DC converter unit when it is in the stopped working state, please refer to the description in Example 1.

[0244] Step S203: When the isolated DC-DC converter unit is in normal working state, turn off the first MOS transistor, so that the isolated DC-DC converter unit performs power conversion on the voltage output by the first voltage input unit, thereby making the voltage of the input LLC resonant synchronous rectifier module within the preset LLC voltage regulation range.

[0245] It should be noted that for the specific working process of the isolated DC-DC converter unit when it is in normal working state, please refer to the description in Example 1.

[0246] In this embodiment, when the isolated DC-DC converter unit is in normal operating state, the first MOSFET is turned off, causing the isolated DC-DC converter unit to perform power conversion on the voltage output from the first voltage input unit, thereby ensuring that the voltage of the input LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range, including:

[0247] When the power conversion module is in normal working state, the first MOSFET is turned off.

[0248] In each switching cycle of the power conversion device, the first and second switching transistors are controlled according to the preset switching control sequence and the half-cycle duty cycle of the switching cycle, so that the isolated DC-DC converter unit performs power conversion on the voltage output by the first voltage input unit, thereby ensuring that the voltage of the input LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range.

[0249] This embodiment enables the isolated DC-DC converter unit to convert the voltage output from the first voltage input unit into power by turning off the first MOSFET and regulating the first and second switching transistors. This ensures that the voltage of the input LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range, thus ensuring the stable and efficient operation of the power conversion device.

[0250] This embodiment determines the operating state of the isolated DC-DC converter unit based on the real-time input voltage and real-time output power of the power conversion device. When the isolated DC-DC converter unit is in the off state, the first MOSFET is turned on, allowing the real-time input voltage to directly enter the LLC resonant synchronous rectification module through the first MOSFET, reducing voltage regulation losses and improving the operating efficiency of the power conversion. When the isolated DC-DC converter unit is in the normal operating state, the first MOSFET is turned off, enabling the isolated DC-DC converter unit to perform power conversion on the voltage output from the first voltage input unit. The voltage input to the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range, avoiding the voltage regulation losses caused by the voltage regulation stage needing to completely convert the input voltage of the power conversion device in the prior art. This achieves the power conversion device maintaining both wide voltage gain and high operating efficiency, improving the operating efficiency of the power conversion device over a wide voltage gain range.

[0251] In summary, this embodiment of the invention, by setting up a partial power conversion module and an LLC resonant synchronous rectification module, wherein the partial power conversion module includes a first voltage input unit, an isolated DC-DC converter unit, and a switching transistor unit, and by electrically connecting the output terminal of the first voltage input unit to the input terminals of the switching transistor unit, the isolated DC-DC converter unit, and the LLC resonant synchronous rectification module respectively, enables the power conversion device to control whether the isolated DC-DC converter unit operates under different input voltage conditions through the switching transistor unit. This ensures that the voltage entering the LLC resonant synchronous rectification module is within the preset LLC voltage regulation range of the LLC resonant synchronous rectification module, avoiding the voltage regulation loss caused by the voltage regulation stage in the prior art needing to completely convert the voltage of the input power conversion device. This achieves the power conversion device maintaining both wide voltage gain and high operating efficiency, improving the operating efficiency of the power conversion device under wide voltage gain. When the real-time input voltage of the power conversion device is within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the isolated DC-DC converter unit is stopped by the switching transistor unit. The real-time input voltage can directly enter the LLC resonant synchronous rectifier module through the switching transistor unit, reducing voltage regulation losses and improving the operating efficiency of the power conversion. When the real-time input voltage of the power conversion device is not within the preset LLC voltage regulation range of the LLC resonant synchronous rectifier module, the isolated DC-DC converter unit is started by the switching transistor unit. This allows the isolated DC-DC converter unit to perform power conversion on the real-time input voltage, ensuring that the voltage entering the LLC resonant synchronous rectifier module remains within the preset LLC voltage regulation range.

[0252] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A power conversion device based on partial power conversion, characterized in that, include: Partial power conversion module and LLC resonant synchronous rectification module; The power conversion module includes: a first voltage input unit, an isolated DC-DC converter unit, and a switching transistor unit; The positive output terminal of the first voltage input unit is electrically connected to the input terminal of the switching transistor unit; The positive output terminal of the first voltage input unit is electrically connected to the positive input terminal of the isolated DC-DC converter unit; The negative output terminal of the first voltage input unit is electrically connected to the negative input terminal of the isolated DC-DC converter unit; The negative output terminal of the first voltage input unit is electrically connected to the negative input terminal of the LLC resonant synchronous rectifier module; The positive output terminal of the isolated DC-DC converter unit is electrically connected to the output terminal of the switching transistor unit; The negative output terminal of the isolated DC-DC converter unit is electrically connected to the input terminal of the switching transistor unit; The output terminal of the switching transistor unit is electrically connected to the positive input terminal of the LLC resonant synchronous rectifier module; The input terminal of the first voltage input unit serves as the voltage input terminal of the power conversion device; The output terminal of the LLC resonant synchronous rectifier module serves as the voltage output terminal of the power conversion device.

2. The power conversion device based on partial power conversion as described in claim 1, characterized in that, The switching unit includes: a first MOSFET; The source of the first MOS transistor serves as the input terminal of the switching transistor unit, and it is electrically connected to the positive output terminal of the first voltage input unit. The source of the first MOS transistor is also electrically connected to the negative output terminal of the isolated DC-DC converter unit; The drain of the first MOS transistor serves as the output terminal of the switching transistor unit, and it is electrically connected to the positive output terminal of the isolated DC-DC converter unit. The drain of the first MOS transistor is electrically connected to the positive input terminal of the LLC resonant synchronous rectifier module.

3. A power conversion device based on partial power conversion as described in claim 2, characterized in that, The isolated DC-DC converter unit includes: a primary-side input control subunit, an isolation subunit, a rectification subunit, and a filtering subunit; The positive input terminal of the primary-side input control subunit serves as the positive input terminal of the isolated DC-DC converter unit, and is electrically connected to the positive output terminal of the first voltage input unit. The negative input terminal of the primary-side input control subunit serves as the negative input terminal of the isolated DC-DC converter unit, and is electrically connected to the negative output terminal of the first voltage input unit. The positive input terminal of the isolation subunit is electrically connected to the positive output terminal of the primary-side input control subunit; The negative input terminal of the isolation subunit is electrically connected to the negative output terminal of the primary input control subunit; The positive output terminal of the isolation subunit is electrically connected to the positive input terminal of the rectifier subunit; The negative output terminal of the isolation subunit is electrically connected to the negative input terminal of the rectifier subunit; The neutral point output terminal of the isolation subunit is electrically connected to the negative input terminal of the filter subunit; The output terminal of the rectifier subunit is electrically connected to the positive input terminal of the filter subunit; The positive output terminal of the filter subunit serves as the positive output terminal of the isolated DC-DC converter unit, and it is electrically connected to the drain of the first MOS transistor. The negative output terminal of the filter subunit serves as the negative output terminal of the isolated DC-DC converter unit, and it is electrically connected to the source of the first MOS transistor.

4. A power conversion device based on partial power conversion as described in claim 3, characterized in that, The primary-side input control subunit includes: a first switch transistor, a second switch transistor, a first capacitor, and a second capacitor; The source of the first switching transistor is electrically connected to the drain of the second switching transistor; The second terminal of the first capacitor is electrically connected to the first terminal of the second capacitor; The first terminal of the first capacitor is electrically connected to the drain of the first switching transistor; The second terminal of the second capacitor is electrically connected to the source of the second switching transistor; The drain of the first switching transistor serves as the positive input terminal of the primary-side input control subunit, and is electrically connected to the positive output terminal of the first voltage input unit. The first terminal of the first capacitor serves as the positive input terminal of the primary-side input control subunit, and is electrically connected to the positive output terminal of the first voltage input unit. The source of the second switching transistor serves as the negative input terminal of the primary-side input control subunit, and is electrically connected to the negative output terminal of the first voltage input unit. The second terminal of the second capacitor serves as the negative input terminal of the primary-side input control subunit, and is electrically connected to the negative output terminal of the first voltage input unit. The source of the first switching transistor serves as the positive output terminal of the primary-side input control subunit, and is electrically connected to the positive input terminal of the isolation subunit. The second terminal of the first capacitor serves as the negative output terminal of the primary-side input control subunit, and is electrically connected to the negative input terminal of the isolation subunit.

5. A power conversion device based on partial power conversion as described in claim 4, characterized in that, The rectifier subunit includes: a first diode and a second diode; The positive terminal of the first diode serves as the positive input terminal of the rectifier subunit, and is electrically connected to the positive output terminal of the isolation subunit. The positive terminal of the second diode serves as the negative input terminal of the rectifier subunit, and is electrically connected to the negative output terminal of the isolation subunit. The negative terminal of the second diode is electrically connected to the negative terminal of the first diode; The negative terminal of the first diode serves as the output terminal of the rectifier subunit, and it is electrically connected to the positive input terminal of the filter subunit.

6. A power conversion device based on partial power conversion as described in claim 5, characterized in that, The filter subunit includes: a fourth inductor and a third capacitor; The second terminal of the fourth inductor is electrically connected to the first terminal of the third capacitor; The first end of the fourth inductor serves as the positive input terminal of the filter subunit, and it is electrically connected to the negative terminal of the first diode. The second terminal of the third capacitor serves as the negative input terminal of the filter subunit, and is electrically connected to the neutral point output terminal of the isolation subunit. The first terminal of the third capacitor serves as the positive output terminal of the filter subunit and is electrically connected to the drain of the first MOS transistor. The second terminal of the third capacitor also serves as the negative output terminal of the filter subunit, and it is electrically connected to the source of the first MOS transistor.

7. A power conversion device based on partial power conversion as described in claim 4, characterized in that, The LLC resonant synchronous rectification module includes: a second voltage input unit, an LLC resonant primary-side switching unit, an LLC resonant primary-side input unit, an LLC resonant secondary-side output unit, a synchronous rectification unit, and a filtering unit; The positive output terminal of the second voltage input unit is electrically connected to the positive input terminal of the LLC resonant primary-side switching unit; The negative output terminal of the second voltage input unit is electrically connected to the negative input terminal of the LLC resonant primary-side switching unit; The positive output terminal of the LLC resonant primary-side switching unit is electrically connected to the positive input terminal of the LLC resonant primary-side input unit. The negative output terminal of the LLC resonant primary-side switching unit is electrically connected to the negative input terminal of the LLC resonant primary-side input unit. The output terminal of the LLC resonant primary-side input unit is coupled to the input terminal of the LLC resonant secondary-side output unit; The positive output terminal of the LLC resonant secondary output unit is electrically connected to the positive input terminal of the synchronous rectification unit. The negative output terminal of the LLC resonant secondary output unit is electrically connected to the negative input terminal of the synchronous rectification unit. The neutral point output terminal of the LLC resonant secondary output unit is electrically connected to the positive input terminal of the filter unit. The output terminal of the synchronous rectification unit is electrically connected to the negative input terminal of the filter unit; The positive input terminal of the second voltage input unit serves as the positive input terminal of the LLC resonant synchronous rectification module, and it is electrically connected to the drain of the first MOS transistor. The negative input terminal of the second voltage input unit serves as the negative input terminal of the LLC resonant synchronous rectifier module, and is electrically connected to the negative output terminal of the first voltage input unit. The output of the filter unit serves as the output of the LLC resonant synchronous rectification module.

8. A control method for a power conversion device based on partial power conversion, characterized in that, A power conversion device based on partial power conversion as described in any one of claims 1 to 7, comprising the following steps: The real-time input voltage and real-time output power of the power conversion device are obtained, and the operating state of the isolated DC-DC converter unit is determined based on the real-time input voltage and real-time output power. When the isolated DC-DC converter unit is in the off state, the first MOSFET is turned on, so that the voltage output by the first voltage input unit is input to the LLC resonant synchronous rectifier module through the first MOSFET, thereby making the voltage input to the LLC resonant synchronous rectifier module within the preset LLC voltage regulation range. When the isolated DC-DC converter unit is in normal operating state, the first MOS transistor is turned off, and the isolated DC-DC converter unit performs power conversion on the voltage output by the first voltage input unit, thereby making the voltage input to the LLC resonant synchronous rectifier module within the preset LLC voltage regulation range.

9. The control method for a power conversion device based on partial power conversion as described in claim 8, characterized in that, The step of determining the operating state of the isolated DC-DC converter unit based on the real-time input voltage and real-time output power includes: Based on the real-time input voltage and real-time output power, plot the first efficiency curve of the partial power conversion module and the second efficiency curve of the LLC resonant synchronous rectifier module, respectively. Based on the preset hysteresis factor and preset judgment formula, and combined with the first efficiency curve and the second efficiency curve, it is determined whether the real-time input voltage is within the preset LLC voltage regulation range. When the real-time input voltage is within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the stopped working state; When the real-time input voltage is not within the preset LLC voltage regulation range, the working state of the isolated DC-DC converter unit is determined to be the normal working state.

10. The control method for a power conversion device based on partial power conversion as described in claim 8, characterized in that, When the isolated DC-DC converter unit is in normal operating state, the first MOSFET is turned off, causing the isolated DC-DC converter unit to perform power conversion on the voltage output from the first voltage input unit, thereby ensuring that the voltage input to the LLC resonant synchronous rectifier module is within a preset LLC voltage regulation range, including: When the power conversion module is in normal working state, the first MOS transistor is turned off. In each switching cycle of the power conversion device, the first and second switching transistors are controlled according to the preset switching control sequence and the half-cycle duty cycle of the switching cycle, so that the isolated DC-DC converter unit performs power conversion on the voltage output by the first voltage input unit, thereby ensuring that the voltage input to the LLC resonant synchronous rectifier module is within the preset LLC voltage regulation range.

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