Multi-interleaved resonant converter and control method and controller thereof

Abstract

The invention discloses a multi-interleaved resonant converter and a control method and a controller thereof, and the method comprises the steps: in a half-bridge mode, if a working frequency is smaller than or equal to a half-bridge-to-full-bridge switching frequency, switching to a full-bridge mode, and switching the working frequency to an initial half-bridge-to-full-bridge switching frequency; in the full-bridge mode, if the working frequency is smaller than or equal to the switching frequency of full-bridge-to-three interleaving, the three-interleaving mode is switched, and the working frequency is switched to the initial frequency of full-bridge-to-three interleaving, and if the working frequency is larger than or equal to the switching frequency of full-bridge-to-half-bridge, the half-bridge mode is switched, and the working frequency is switched to the initial frequency of full-bridge-to-half-bridge; in the three-interlacing mode, if the working frequency is larger than or equal to the switching frequency of the three-interlacing switching full bridge, the full bridge mode is switched, and the working frequency is switched to the initial frequency of the three-interlacing switching full bridge, the output efficiency of the transformer is maximized while smooth switching between the modes is guaranteed, the method is simple and reliable, and control cost does not need to be additionally increased.

Description

Technical Field

[0001] The present invention relates to the field of circuits, and in particular to a multi-interleaved resonant converter and a control method and a controller thereof. Background Art

[0002] The LLC resonant converter has a simple structure, and the switching devices can work in a soft switching state, so the converter has the characteristics of high efficiency and high reliability. LLC resonant converters can be divided into half-bridge, full-bridge and three-interleaved types according to the number of primary bridge arms. Among them, the three-interleaved LLC with a star connection on the primary side can reduce the peak current of the primary resonant cavity and the ripple of the output current through the interleaved operation of the three bridge arms, which is suitable for high-power power supply output occasions. However, since the six switch tubes of the three-interleaved LLC work at high frequency and non-soft opening when light load, its efficiency is low when light load. Specifically, the three-interleaved LLC can reduce the ripple of the output current while widening the output power of the converter through the interleaved operation of the three bridge arms. However, due to the design limitation of the maximum switching frequency at light load, the output gain of the three-interleaved LLC converter is too large, and it is necessary to control the stability of the output by increasing the dead zone between the upper and lower tubes to adjust the duty cycle. However, the larger dead zone will cause the switch tube to work in a hard-on state, and the three-interleaved LLC has a large number of switches. The high-frequency hard-on switching state makes the converter extremely inefficient at light load.

[0003] Under the condition of small output gain or light load, compared with three-interleaved LLC, half-bridge LLC and full-bridge LLC have lower operating frequency, fewer switch tubes, and the switch is easy to work in the soft-open state, and its efficiency is better than three-interleaved LLC. Therefore, in the application of high-power resonant power supply, switching the resonant LLC to work in half-bridge, full-bridge and three-interleaved modes according to different output powers is conducive to the efficiency optimization and performance optimization of the power supply. For example, the patent application with publication number CN 116365890 A mentions that when the load power is greater than 70% of the rated power, the converter works in a three-level T-type three-phase interleaved LLC conversion form; when the load power is between 30% and 70% of the rated power, the converter works in a three-level T-type full-bridge LLC converter; when the load power is less than 30% of the rated power, the converter works in a three-level T-type half-bridge LLC conversion form. This scheme only discloses the switching trend of the three modes during the power increase / decrease process, which is only a concept and cannot be realized in actual control. For example, when deciding to switch from one mode to another, how to switch and how to determine the operating parameters are not disclosed, so it cannot be actually implemented.

[0004] At present, the optimization of LLC resonant power supply efficiency is mainly divided into hardware circuit, software control and other aspects. Improving power supply efficiency through hardware circuit optimization will inevitably affect the cost and control complexity of the power supply. Therefore, the design of the existing scheme is to improve the power supply efficiency by changing the working mode of the full-bridge LLC without increasing the cost of the power supply. However, this scheme adds a transition process when switching the half-full-bridge mode, which is easy to cause fluctuations in the output voltage and current.

[0005] The above information disclosed in this Background section is included only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is currently known to a person of ordinary skill in the art. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a multi-interleaved resonant converter and a control method and a controller thereof in view of the above-mentioned defects of the prior art.

[0007] The technical solution adopted by the present invention to solve its technical problem is:

[0008] On the one hand, a control method of a multi-interleaved resonant converter is constructed, wherein the converter includes a multi-phase switching circuit arranged at an input side, and the method includes:

[0009] Determining a current power frequency and operating mode of the converter;

[0010] When the converter is in the half-bridge mode, if the operating frequency is less than or equal to the switching frequency of the half-bridge to full-bridge mode, the converter is controlled to switch from the half-bridge mode to the full-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the half-bridge to full-bridge mode;

[0011] When the converter is in full-bridge mode, if the operating frequency is less than or equal to the switching frequency of the full-bridge switching three-interleaved, the converter is controlled to switch from the full-bridge mode to the three-interleaved mode, and the operating frequency is controlled to switch to the initial frequency of the full-bridge switching three-interleaved; if the operating frequency is greater than or equal to the switching frequency of the full-bridge switching half-bridge, the converter is controlled to switch from the full-bridge mode to the half-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the full-bridge switching half-bridge;

[0012] When the converter is in the three-interleaved mode, if the operating frequency is greater than or equal to the switching frequency of the three-interleaved full-bridge, the converter is controlled to switch from the three-interleaved mode to the full-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the three-interleaved full-bridge;

[0013] Among them, each switching frequency is a maximum efficiency point set in advance based on the efficiency and power between different modes;

[0014] Wherein, each initial frequency and the switching frequency corresponding thereto need to satisfy the following gain relationship: the gain difference of the converter is within a preset error range.

[0015] Furthermore, in the method described in the present invention, there is the following frequency relationship between the initial frequency at which each mode is switched to an adjacent mode and the switching frequency at which the adjacent mode is switched to the mode:

[0016] The switching frequency of half-bridge to full-bridge is less than the initial frequency of full-bridge to half-bridge by one hysteresis width, the switching frequency of full-bridge to three-interlace is less than the initial frequency of three-interlace to full-bridge by one hysteresis width, the switching frequency of three-interlace to full-bridge is greater than the initial frequency of full-bridge to three-interlace by one hysteresis width, and the switching frequency of full-bridge to half-bridge is greater than the initial frequency of half-bridge to full-bridge by one hysteresis width.

[0017] Furthermore, the method further includes: when the operating frequency meets the switching requirement of a certain mode, further monitoring whether the next continuous preset number of control cycles also meet the switching requirement of the certain mode, and determining to switch the mode only if it does.

[0018] Furthermore, the method further comprises: obtaining the impedance of the current output load, substituting the impedance of the current output load into a switching point-load relationship established in advance by fitting, and obtaining each switching frequency corresponding to the impedance of the current output load;

[0019] The switching point-load relationship is as follows:

[0020]

[0021] Among them, Freq_Mode_HTOF represents the switching frequency of half-bridge to full-bridge, Freq_Mode_FTOT represents the switching frequency of full-bridge to three-interleaved, Freq_Mode_TTOF represents the switching frequency of three-interleaved to full-bridge, Freq_Mode_FTOH represents the switching frequency of full-bridge to half-bridge, R represents the impedance of the output load, k1, k2, k3, k4 represent the slope, and b1, b2, b3, b4 represent the intercept.

[0022] Furthermore, the method further includes obtaining the switching point-load relationship based on the following processing:

[0023] The converter is operated under various load conditions, and the switching frequency under each load condition is determined by: measuring a power-efficiency curve of the converter efficiency as the power changes when the transformer is in a half-bridge mode, a full-bridge mode, and a three-interleaved mode; and determining the switching frequency between different modes according to the intersection of the power-efficiency curves in different modes;

[0024] Based on the impedance of the output load under various load conditions and the corresponding switching frequencies, the switching point-load relationship is substituted into the switching point-load relationship to obtain the values ​​of the slope and the intercept through fitting.

[0025] Furthermore, in the method of the present invention, determining the switching frequency between different modes according to the intersection of the power-efficiency curves in different modes specifically includes:

[0026] Find the intersection of the power-efficiency curves in the half-bridge mode and the full-bridge mode, determine the power corresponding to the intersection as the first target power, determine the frequency corresponding to the first target power as the switching frequency of half-bridge to full-bridge, calculate the initial frequency of half-bridge to full-bridge according to the gain relationship, and calculate the switching frequency of full-bridge to half-bridge according to the initial frequency of half-bridge to full-bridge and the frequency relationship; or, find the intersection of the power-efficiency curves in the half-bridge mode and the full-bridge mode, determine the power corresponding to the intersection as the first target power, determine the frequency corresponding to the first target power as the switching frequency of full-bridge to half-bridge, calculate the initial frequency of full-bridge to half-bridge according to the gain relationship, and calculate the switching frequency of half-bridge to full-bridge according to the initial frequency of full-bridge to half-bridge and the frequency relationship;

[0027] Find the intersection of the power-efficiency curves in the full-bridge mode and the three-interleaved mode, determine the power corresponding to the intersection as the second target power, determine the frequency corresponding to the second target power as the switching frequency of the full-bridge to three-interleaved mode, calculate the initial frequency of the full-bridge to three-interleaved mode according to the gain relationship, and calculate the switching frequency of the three-interleaved mode of the full bridge according to the initial frequency of the full-bridge to three-interleaved mode and the frequency relationship; or, find the intersection of the power-efficiency curves in the full-bridge mode and the three-interleaved mode, determine the power corresponding to the intersection as the second target power, determine the frequency corresponding to the second target power as the switching frequency of the three-interleaved mode of the full bridge, calculate the initial frequency of the three-interleaved mode of the full bridge according to the gain relationship, and calculate the switching frequency of the full bridge to three-interleaved mode according to the initial frequency of the three-interleaved mode of the full bridge and the frequency relationship.

[0028] Furthermore, in the method of the present invention, the transformer includes a multi-phase switching circuit, the multi-phase switching circuit includes multi-phase bridge arms connected in parallel, each phase bridge arm includes upper and lower tubes connected in series, and the method further includes:

[0029] When it is necessary to control the transformer to enter the half-bridge mode: the upper and lower tube drive signals of one phase bridge arm are complementary, the upper tube drive signal of the other phase bridge arm is maintained at a low level, the lower tube drive signal is maintained at a high level, and the upper and lower tube drives of the other phase bridge arms are maintained at a low level;

[0030] When it is necessary to control the transformer circuit to enter the full-bridge mode: the upper and lower tube driving signals of two-phase bridge arms are complementary, and the phases between the two-phase bridge arms are staggered by 180 degrees, and the upper and lower tube driving signals of other phase bridge arms are maintained at a low level;

[0031] When it is necessary to control the transformer to enter the three-interleaved mode: the driving signals of the upper and lower tubes of each phase bridge arm are complementary to each other, and the phases between adjacent phase bridge arms are staggered by 2π / M degrees, where M represents the number of phases of the multi-phase switching circuit.

[0032] In a second aspect, a multi-interleaved resonant converter is constructed, which includes a multi-phase switching circuit, a transformer circuit, a sampling circuit, and a control circuit for generating waves to control the multi-phase switching circuit, and the control circuit is used to execute the method described in any of the preceding items.

[0033] In a third aspect, a controller is constructed, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the steps of the method described in any of the preceding items are implemented.

[0034] The multi-interleaved resonant converter and its control method and controller of the present invention have the following beneficial effects: the present invention controls the converter to operate in half-bridge, full-bridge and three-interleaved modes respectively according to its operating frequency, and maximizes the transformer output efficiency while ensuring smooth switching between modes by setting a reasonable switching frequency. The method is simple and reliable, and does not require additional control costs. Furthermore, by determining the switching points of different output loads through pre-fitted relationship and adding a switching anti-shake mechanism, the transformer can achieve maximum efficiency output while completing smooth mode switching. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings in the following description are only embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on the provided drawings without creative work:

[0036] Figure 1 is a schematic diagram of a control method for a multi-interleaved resonant converter of the present invention;

[0037] Figure 2 It is a schematic diagram of the structure of a multi-interleaved resonant converter applied to a high-power power supply;

[0038] Figure 3 It is a schematic diagram of a three-phase switching circuit;

[0039] Figure 4 It is a schematic diagram of the driving waveform of the three-phase switching circuit;

[0040] Figure 5 It is a detailed method flow chart of a specific embodiment of the multi-interleaved resonant converter control method of the present invention. DETAILED DESCRIPTION

[0041] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. Typical embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. It should be understood that the embodiments of the present invention and the specific features in the embodiments are detailed descriptions of the technical solutions of the present application, rather than limitations on the technical solutions of the present application. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0042] refer to Figure 2 , taking the converter applied to a high-power power supply as an example for explanation. The multi-interleaved resonant converter includes a multi-phase switching circuit, a transformer circuit, a sampling circuit, and a control circuit for generating waves to control the multi-phase switching circuit, and the control circuit is used to execute the method described in the present invention. The multi-phase switching circuit is connected to the external input circuit and the input side of the transformer circuit, and the output side of the transformer circuit is connected to the external input load. The input circuit provides a stable DC voltage for the subsequent circuit, and the multi-phase switching circuit and the resonant cavity generate AC voltage and current on the primary side of the transformer. The voltage and current are converted into electric energy through the transformer, and then output to the load through output rectification and filtering. The sampling circuit is connected to the output side of the transformer circuit and is used to sample information such as voltage, current, and power. The control circuit controls the multi-phase switching circuit according to the information fed back by the sampling circuit. The multi-phase switching circuit includes multi-phase bridge arms connected in parallel to each other, and each phase bridge arm includes two switch tubes connected in series, which are respectively recorded as upper and lower tubes. The control circuit is used to control the state of each upper and lower tube so that the transformer works in half-bridge, full-bridge and three-interleaved modes respectively. When the hardware parameters are consistent and the output gain is the same, the frequency relationship of the three modes is three-interleaved, full-bridge, and half-bridge from large to small; when the operating frequency is the same, the gain relationship of the three modes is three-interleaved, full-bridge, and half-bridge from large to small. It can be seen that when the circuit mode is switched to half-bridge and full-bridge mode under light load, the switching frequency can be reduced while reducing the converter gain, and the switch tube is more likely to work in the soft-open state, thereby improving the efficiency of the converter.

[0043] refer to Figure 1 The multi-interleaved resonant converter control method of the present invention is executed by a control circuit, and the method includes:

[0044] S100: Determine the current power frequency and operating mode of the converter;

[0045] The control circuit of the transformer will adjust the switching frequency of the multi-phase switching circuit according to the power demand of the converter and the power fed back by the sampling circuit. This frequency is also the working frequency mentioned in this article. The present invention will track this frequency and perform mode switching control through subsequent steps S200-S400 according to this frequency to put it in different modes. It can be understood that there is no necessary connection between the following steps S200-S400 in terms of timing. Specifically, the multi-phase switching circuit can be placed in different modes by driving each phase bridge arm in the following manner:

[0046] (A) When it is necessary to control the transformer to enter the half-bridge mode (denoted as Mode_Half): the upper and lower tube drive signals of one phase bridge arm of the multi-phase switching circuit are complementary, the upper tube drive signal of the other phase bridge arm is maintained at a low level, the lower tube drive signal is maintained at a high level, and the upper and lower tube drives of the other phase bridge arms are maintained at a low level;

[0047] (B) When it is necessary to control the multi-phase switch circuit to enter the full-bridge mode (denoted as Mode_Full): the upper and lower tube drive signals of two-phase bridge arms of the multi-phase switch circuit are complementary, and the phases between the two-phase bridge arms are staggered by 180 degrees, and the upper and lower tube drive signals of the other phase bridge arms are maintained at a low level;

[0048] (C) When it is necessary to control the multi-phase switching circuit to enter the three-interleaved mode (denoted as Mode_Three): the driving signals of the upper and lower tubes of each phase bridge arm of the multi-phase switching circuit are complementary to each other, and the phases between adjacent phase bridge arms are staggered by 2π / M degrees, where M represents the number of phases of the multi-phase switching circuit.

[0049] For example, in a specific embodiment, the converter is a three-phase interleaved LLC resonant converter, so its multi-phase switching circuit is a three-phase switching circuit. Figure 3 The three-phase switching circuit includes three-phase bridge arms, which are respectively recorded as A, B, and C phase bridge arms. The driving signals of the three-phase bridge arms are PWM1A, PWM1B, PWM2A, PWM2B, PWM3A, and PWM3B respectively. The driving waveforms corresponding to the three modes are as follows Figure 4 shown.

[0050] (A) When the driving signals of the upper and lower tubes of the three-phase bridge arms A, B, and C are complementary and their phases are staggered by 120 degrees, the converter operates in the three-interleaved mode.

[0051] (B) When the upper and lower tube drive signals PWM1A and PWM1B of the A-phase bridge arm are complementary, the upper and lower tube drive signals PWM2A and PWM2B of the B-phase bridge arm are complementary, and the upper and lower tube drives of the C-phase bridge arm are maintained at a low level, the drive signals between the A and B phases are staggered 180 degrees with each other, then the converter operates in full-bridge mode.

[0052] (C) When the upper and lower tube drive signals PWM1A and PWM1B of the A-phase bridge arm are complementary, the upper tube drive signal PWM2A of the B-phase bridge arm maintains a low level, the lower tube drive signal PWM2B maintains a high level, and the upper and lower tube drives of the C-phase bridge arm maintain a low level, the converter operates in half-bridge mode.

[0053] It should be noted that there are many configuration methods for implementing three-mode drive waveforms in a control chip. It is necessary to ensure the correctness of the PWM drive signal and no direct-through wave is generated. There are two specific methods as follows. This embodiment uses the second method as an example.

[0054] (1) By changing the PWM comparison value that generates high and low levels, the drive signal is changed to generate a constant low or constant high drive waveform. Using this method, the PWM wave generation method does not need to be changed, only the comparison value needs to be changed.

[0055] (2) By changing the PWM software forced wave mode, the PWM comparison value does not work when the software forces the wave. At this time, the PWM output is forced to be a constant high level or a constant low level according to the wave needs. When using this method, it is necessary to configure the PWM forced wave to take effect when the PWM count time base is equal to 0.

[0056] S200: When the converter is in the half-bridge mode, if the operating frequency is less than or equal to the switching frequency of the half-bridge to full-bridge mode, control the converter to switch from the half-bridge mode to the full-bridge mode, and control the operating frequency to switch to the initial frequency of the half-bridge to full-bridge mode;

[0057] S300: When the converter is in the full-bridge mode, if the operating frequency is less than or equal to the switching frequency of the full-bridge switching to three-interleaved mode, the converter is controlled to switch from the full-bridge mode to the three-interleaved mode, and the operating frequency is controlled to switch to the initial frequency of the full-bridge switching to three-interleaved mode; if the operating frequency is greater than or equal to the switching frequency of the full-bridge switching to half-bridge, the converter is controlled to switch from the full-bridge mode to the half-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the full-bridge switching to half-bridge;

[0058] S400: When the converter is in the three-interleaved mode, if the operating frequency is greater than or equal to the switching frequency of the three-interleaved full-bridge, control the converter to switch from the three-interleaved mode to the full-bridge mode, and control the operating frequency to switch to the initial frequency of the three-interleaved full-bridge;

[0059] Preferably, in order to prevent repeated switching between modes due to unstable output, the method further includes: when the operating frequency meets the switching requirements of a certain mode, further monitoring whether the next preset number of control cycles also meet the switching requirements of the certain mode, and determining to switch the mode only if they do. That is, a delay anti-shake mechanism can be added during mode switching, and the delay anti-shake is implemented in the form of cumulative counting. When the switching condition meets the cumulative operation of N control cycles, the mode conversion is performed, which can avoid the situation where the output disturbance causes repeated mode switching. For example, a corresponding count value can be configured for each switching frequency. When the operating frequency of the converter reaches a certain switching frequency requirement, the corresponding count value is increased by one. If the count value is continuously increased until it reaches N, it is considered that the time to meet the switching point requirement continues to exceed the switching anti-shake time threshold (N*T, T is a control cycle), and then the corresponding mode switching can be truly executed.

[0060] Remember that the switching frequency of half-bridge switching to full-bridge is Freq_Mode_HTOF, the switching frequency of full-bridge switching to three-interleave is Freq_Mode_FTOT, the switching frequency of three-interleave switching to full-bridge is Freq_Mode_TTOF, the switching frequency of full-bridge switching to half-bridge is Freq_Mode_FTOH, the initial frequency of half-bridge switching to full-bridge is Freq_Mode_HTOF_Init, the initial frequency of full-bridge switching to three-interleave is Freq_Mode_FTOT_Init, the initial frequency of three-interleave switching to full-bridge is Freq_Mode_TTOF_Init, and the initial frequency of full-bridge switching to half-bridge is Freq_Mode_FTOH_Init.

[0061] The relationship between the above switching frequencies is as follows:

[0062]

[0063] In order to prevent repeated switching, in the present invention, there is the following frequency relationship between the initial frequency of each mode switching to the adjacent mode and the switching frequency of the adjacent mode switching to the mode: the switching frequency of half-bridge switching to full-bridge is less than the initial frequency of full-bridge switching to half-bridge by one hysteresis width, the switching frequency of full-bridge switching to three-interleaved switching is less than the initial frequency of three-interleaved switching to full-bridge by one hysteresis width, the switching frequency of three-interleaved switching to full-bridge is greater than the initial frequency of full-bridge switching to three-interleaved by one hysteresis width, and the switching frequency of full-bridge switching to half-bridge is greater than the initial frequency of half-bridge switching to full-bridge by one hysteresis width, that is:

[0064]

[0065] Among them, delta_Freq is the hysteresis width, which is set based on experience.

[0066] There are two points to note about the switch point setting:

[0067] (1) Each initial frequency and the corresponding switching frequency need to satisfy the following gain relationship: the difference in gain of the converter is within a preset error range. Let Gain(x) represent the frequency gain relationship, where x represents the frequency. The gain relationship is expressed as follows:

[0068]

[0069] Gain-error is a very small value, set based on experience.

[0070] (2) Each switching frequency is a pre-set point of highest efficiency based on the efficiency and power between different modes. The switching point is not a fixed and unique point, and the switching points corresponding to different loads may be different.

[0071] In order to determine the switching point corresponding to each load, the switching point-load relationship can be pre-fitted before the converter is officially applied to a specific scenario, so that the converter can operate at optimal efficiency under different load conditions; when the converter is officially applied, the impedance of the current output load is obtained, and the impedance of the current output load is substituted into the switching point-load relationship established in advance by fitting, to obtain the switching frequencies corresponding to the impedance of the current output load.

[0072] Specifically, the fitting process of the switching point-load relationship is as follows:

[0073] (1) The switching point-load relationship is established as follows:

[0074]

[0075] Among them, Freq_Mode_HTOF represents the switching frequency of half-bridge to full-bridge, Freq_Mode_FTOT represents the switching frequency of full-bridge to three-interleaved, Freq_Mode_TTOF represents the switching frequency of three-interleaved to full-bridge, Freq_Mode_FTOH represents the switching frequency of full-bridge to half-bridge, R represents the impedance of the output load, k1, k2, k3, k4 represent the slope, and b1, b2, b3, b4 represent the intercept.

[0076] (2) Obtain sample data;

[0077] Specifically, the converter is operated under various load conditions, and the switching frequency under each load condition is determined by: measuring the power-efficiency curve of the converter efficiency changing with power when the transformer is in half-bridge mode, full-bridge mode, and three-interleaved mode respectively; determining the switching frequency between different modes according to the intersection of the power-efficiency curves in different modes;

[0078] Wherein, determining the switching frequency between different modes according to the intersection of the power-efficiency curves in different modes specifically includes:

[0079] (1) Determination of the switching frequency of half-bridge to full-bridge and full-bridge to half-bridge:

[0080] (1a) finding the intersection of the power-efficiency curves in the half-bridge mode and the full-bridge mode, and determining the power corresponding to the intersection as the first target power;

[0081] (1b) Determine the frequency corresponding to the first target power as the switching frequency of half-bridge to full-bridge, for example, directly regard the first target frequency as the switching frequency of half-bridge to full-bridge. The initial frequency of half-bridge to full-bridge is calculated according to the gain relationship (specifically, as shown in equation (3)), and the switching frequency of full-bridge to half-bridge is calculated according to the initial frequency of half-bridge to full-bridge and the frequency relationship (specifically, as shown in equation (2)). For example, if the frequency range is 0 to 150, all three modes will operate in this frequency range. However, at the same gain, the frequency of half-bridge is less than the frequency of full-bridge and less than the frequency of three interlacings. The frequency of half-bridge to full-bridge corresponds to the frequency of half-bridge, and the initial frequency of half-bridge to full-bridge corresponds to the frequency of switching to full-bridge. For example, suppose that the power 60KHZ corresponding to one of the intersections is determined by fitting as the switching frequency of half-bridge to full-bridge, that is, This means that the half-bridge switches to the full-bridge at a frequency of 60KHZ. At this time, if the same gain is guaranteed according to equation (3), the full-bridge should work at 90KHZ, which means that the initial frequency of the half-bridge switching to the full-bridge needs to be set to Freq_Mode_FTOH_Init = 90KHZ. Then the switching frequency of the full-bridge switching to the half-bridge can be obtained according to equation (3):

[0082] Of course, (1b) can also be changed to: determine the frequency corresponding to the first target power as the switching frequency of the full-bridge to half-bridge, calculate the initial frequency of the full-bridge to half-bridge according to the gain relationship, and calculate the switching frequency of the half-bridge to full-bridge according to the initial frequency of the full-bridge to half-bridge and the frequency relationship.

[0083] (2) Determination of the switching frequency of the full-bridge switching three-interleaved switching and the switching frequency of the three-interleaved switching full-bridge switching:

[0084] (2a) finding the intersection of the power-efficiency curves in the full-bridge mode and the three-interleaved mode, and determining the power corresponding to the intersection as the second target power;

[0085] (2b) Determine the frequency corresponding to the second target power as the switching frequency of the full-bridge three-interleaved switching, calculate the initial frequency of the full-bridge three-interleaved switching according to the gain relationship, and calculate the switching frequency of the three-interleaved switching to the full bridge according to the initial frequency of the full-bridge three-interleaved switching and the frequency relationship.

[0086] Of course, (2b) can also be changed to: determine that the frequency corresponding to the second target power is the switching frequency of the three-interleaved full bridge, calculate the initial frequency of the three-interleaved full bridge according to the gain relationship, and calculate the switching frequency of the full bridge to three-interleaved according to the initial frequency of the three-interleaved full bridge and the frequency relationship.

[0087] (3) Based on the impedance of the output load under various load conditions and the corresponding switching frequencies, the switching point-load relationship is substituted into the switching point-load relationship to obtain the values ​​of the slope and the intercept through fitting.

[0088] Combine the following Figure 5 , taking the switch circuit as a three-phase switch circuit as an example, the mode switching process of this embodiment is demonstrated in combination with the process of output power change:

[0089] (1) When the output power increases from zero to the maximum power, the converter working mode is half-bridge Mode_Half. At this time, the converter working frequency is the maximum. As the output power increases, the converter working frequency gradually decreases. When the working frequency is less than or equal to the switching frequency Freq_Mode_HTOF of half-bridge to full-bridge, the count value of half-bridge to full-bridge is accumulated Freq_Mode_HTOF_Cnt++. When the accumulation exceeds the switching anti-shake time threshold, the converter working frequency is changed to be equal to the initial frequency Freq_Mode_HTOF_Init of half-bridge to full-bridge, Freq_Mode_HTOF_Cnt is cleared, and the converter working mode is marked as full-bridge Mode_Full. As the output power increases further, the operating frequency of the converter gradually decreases. When the operating frequency is less than or equal to the switching frequency Freq_Mode_FTOT of the full-bridge three-interleaved mode, the count value of the full-bridge three-interleaved mode is accumulated by Freq_Mode_FTOT_Cnt++. When the accumulation exceeds the switching anti-shake time threshold, the frequency of the converter is changed to be equal to the initial frequency Freq_Mode_FTOT_Init of the full-bridge three-interleaved mode, Freq_Mode_FTOT_Cnt is cleared, and the operating mode of the converter is marked as full-bridge Mode_Three.

[0090] (2) When the output power gradually decreases from the maximum power to zero, the working mode of the converter is switched from three-interleaved to full-bridge mode and then to half-bridge mode. When the output power gradually decreases, the switching frequency of the converter gradually increases. When the working frequency is greater than or equal to the switching frequency Freq_Mode_TTOF of the three-interleaved full-bridge, the count value of the three-interleaved full-bridge is accumulated Freq_Mode_TTOF_Cnt++. When the accumulation exceeds the switching anti-shake time threshold, the frequency of the converter is changed to be equal to the initial frequency Freq_Mode_TTOF_Init of the three-interleaved full-bridge, Freq_Mode_TTOF_Cnt is cleared, and the working mode of the converter is marked as full-bridge Mode_Full. As the output power further decreases, the operating frequency of the converter gradually increases. When the operating frequency is greater than or equal to the switching frequency Freq_Mode_FTOH of the full-bridge to half-bridge, the count value of the full-bridge to half-bridge is accumulated Freq_Mode_FTOH_Cnt++. When the accumulation exceeds the switching anti-shake time threshold, the frequency of the converter is changed to be equal to the initial frequency Freq_Mode_FTOH_Init of the full-bridge to half-bridge, Freq_Mode_FTOH_Cnt is cleared, and the operating mode of the converter is marked as full-bridge Mode_Half.

[0091] (3) After the mode switching judgment is completed, the PWM wave configuration is performed according to the converter mode, and the half-bridge, full-bridge and three-interleaved modes are realized respectively by software forced wave generation.

[0092] It should be noted that the above embodiments are based on a three-phase interleaved LLC resonant converter (the switching circuit is a three-phase switching circuit) to achieve switching between different modes. When other types of multi-phase interleaved converters adopt such methods, they are similar to the method of the present invention, such as two-phase, three-phase, four-phase and other multi-phase interleaved converters; in addition, when other types of resonant converters adopt such methods, they are similar to the method of the present invention, such as LCC resonant converters; in addition, the embodiment of the present invention is based on the variable mode control of the three-phase interleaved LLC resonant converter to optimize the power efficiency, and other such methods are similar to the method of the present invention when used in wide input, wide output, wide gain range and other occasions; the method of setting the switching point during the mode switching process and the fitting method of the switching frequency and the load, this patent adopts a linear fitting, and other types of fitting methods are similar to the present invention; the present invention takes the three-interleaved LLC resonant converter as an example for explanation, and there are many choices of working bridge arms in the half-bridge and full-bridge modes. When the switching bridge arm is selected as other schemes, it is similar to the method of the present invention.

[0093] In summary, in the method embodiment of the present invention, the converter is controlled to work in half-bridge, full-bridge and three-interleaved modes respectively according to its operating frequency, and a reasonable switching frequency is set to maximize the output efficiency of the transformer while ensuring smooth switching between modes. The method is simple and reliable, and does not require additional control costs. Furthermore, by determining the switching points of different output loads through pre-fitted relationship and adding a switching anti-shake mechanism, the transformer can achieve the maximum efficiency output of the power supply while completing smooth mode switching, thereby achieving high-efficiency and high-reliability power supply performance.

[0094] A person skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing related hardware through a program. The program can be stored in a storage medium. When the program is executed, it can include the processes of the embodiments of the above-mentioned methods.

[0095] Based on the same inventive concept, the present invention also claims protection for a controller, which includes a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the steps of the method described in the above embodiment are implemented.

[0096] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0097] Terms containing ordinal numbers such as "first", "second" etc. used in this specification can be used to describe various constituent elements, but these constituent elements are not limited by these terms. The purpose of using these terms is only to distinguish one constituent element from other constituent elements. For example, without departing from the scope of the present invention, the first constituent element can be named as the second constituent element, and similarly, the second constituent element can also be named as the first constituent element. The words "equal", "same", "simultaneous" or other similar terms are not limited to absolute equality or sameness in mathematical terms. When implementing the rights described in this patent, they can be close in an engineering sense or within an acceptable error range. The "connected" or "connected" not only includes directly connecting two entities, but also indirectly connecting through other entities with beneficial improvement effects.

[0098] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for controlling a multi-interleaved resonant converter, wherein the converter comprises a multi-phase switching circuit arranged at an input side, characterized in that: The method comprises: Determining a current power frequency and operating mode of the converter; When the converter is in the half-bridge mode, if the operating frequency is less than or equal to the switching frequency of the half-bridge to full-bridge mode, the converter is controlled to switch from the half-bridge mode to the full-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the half-bridge to full-bridge mode; When the converter is in full-bridge mode, if the operating frequency is less than or equal to the switching frequency of the full-bridge switching three-interleaved, the converter is controlled to switch from the full-bridge mode to the three-interleaved mode, and the operating frequency is controlled to switch to the initial frequency of the full-bridge switching three-interleaved; if the operating frequency is greater than or equal to the switching frequency of the full-bridge switching half-bridge, the converter is controlled to switch from the full-bridge mode to the half-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the full-bridge switching half-bridge; When the converter is in the three-interleaved mode, if the operating frequency is greater than or equal to the switching frequency of the three-interleaved full-bridge, the converter is controlled to switch from the three-interleaved mode to the full-bridge mode, and the operating frequency is controlled to switch to the initial frequency of the three-interleaved full-bridge; Among them, each switching frequency is a maximum efficiency point set in advance based on the efficiency and power between different modes; Wherein, each initial frequency and the switching frequency corresponding thereto need to satisfy the following gain relationship: the gain difference of the converter is within a preset error range.

2. The method according to claim 1, characterized in that There is the following frequency relationship between the initial frequency at which each mode switches to the adjacent mode and the switching frequency at which the adjacent mode switches to the mode: The switching frequency of half-bridge to full-bridge is less than the initial frequency of full-bridge to half-bridge by one hysteresis width, the switching frequency of full-bridge to three-interlace is less than the initial frequency of three-interlace to full-bridge by one hysteresis width, the switching frequency of three-interlace to full-bridge is greater than the initial frequency of full-bridge to three-interlace by one hysteresis width, and the switching frequency of full-bridge to half-bridge is greater than the initial frequency of half-bridge to full-bridge by one hysteresis width.

3. The method according to claim 1, characterized in that The method further includes: when the operating frequency meets the switching requirement of a certain mode, further monitoring whether the next continuous preset number of control cycles also meet the switching requirement of the certain mode, and determining to switch the mode only if it does.

4. The method according to claim 1, characterized in that The method further includes: obtaining the impedance of the current output load, substituting the impedance of the current output load into a switching point-load relationship established in advance by fitting, and obtaining each switching frequency corresponding to the impedance of the current output load; The switching point-load relationship is as follows: Among them, Freq_Mode_HTOF represents the switching frequency of half-bridge to full-bridge, Freq_Mode_FTOT represents the switching frequency of full-bridge to three-interleaved, Freq_Mode_TTOF represents the switching frequency of three-interleaved to full-bridge, Freq_Mode_FTOH represents the switching frequency of full-bridge to half-bridge, R represents the impedance of the output load, k1, k2, k3, k4 represent the slope, and b1, b2, b3, b4 represent the intercept.

5. The method according to claim 4, characterized in that The method further includes obtaining the switching point-load relationship based on the following processing: The converter is operated under various load conditions, and the switching frequency under each load condition is determined by: measuring a power-efficiency curve of the converter efficiency as the power changes when the transformer is in a half-bridge mode, a full-bridge mode, and a three-interleaved mode; and determining the switching frequency between different modes according to the intersection of the power-efficiency curves in different modes; Based on the impedance of the output load under various load conditions and the corresponding switching frequencies, the switching point-load relationship is substituted into the switching point-load relationship to obtain the values ​​of the slope and the intercept through fitting.

6. The method according to claim 5, characterized in that The determining of the switching frequency between different modes according to the intersection of the power-efficiency curves in different modes specifically includes: Find the intersection of the power-efficiency curves in the half-bridge mode and the full-bridge mode, determine the power corresponding to the intersection as the first target power, determine the frequency corresponding to the first target power as the switching frequency of half-bridge to full-bridge, calculate the initial frequency of half-bridge to full-bridge according to the gain relationship, and calculate the switching frequency of full-bridge to half-bridge according to the initial frequency of half-bridge to full-bridge and the frequency relationship; or, find the intersection of the power-efficiency curves in the half-bridge mode and the full-bridge mode, determine the power corresponding to the intersection as the first target power, determine the frequency corresponding to the first target power as the switching frequency of full-bridge to half-bridge, calculate the initial frequency of full-bridge to half-bridge according to the gain relationship, and calculate the switching frequency of half-bridge to full-bridge according to the initial frequency of full-bridge to half-bridge and the frequency relationship; Find the intersection of the power-efficiency curves in the full-bridge mode and the three-interleaved mode, determine the power corresponding to the intersection as the second target power, determine the frequency corresponding to the second target power as the switching frequency of the full-bridge to three-interleaved mode, calculate the initial frequency of the full-bridge to three-interleaved mode according to the gain relationship, and calculate the switching frequency of the three-interleaved mode of the full bridge according to the initial frequency of the full-bridge to three-interleaved mode and the frequency relationship; or, find the intersection of the power-efficiency curves in the full-bridge mode and the three-interleaved mode, determine the power corresponding to the intersection as the second target power, determine the frequency corresponding to the second target power as the switching frequency of the three-interleaved mode of the full bridge, calculate the initial frequency of the three-interleaved mode of the full bridge according to the gain relationship, and calculate the switching frequency of the full bridge to three-interleaved mode according to the initial frequency of the three-interleaved mode of the full bridge and the frequency relationship.

7. The method according to claim 1, characterized in that The transformer includes a multi-phase switching circuit, the multi-phase switching circuit includes multi-phase bridge arms connected in parallel, each phase bridge arm includes upper and lower tubes connected in series, and the method further includes: When it is necessary to control the transformer to enter the half-bridge mode: the upper and lower tube drive signals of one phase bridge arm of the multi-phase switching circuit are complementary, the upper tube drive signal of the other phase bridge arm is maintained at a low level, the lower tube drive signal is maintained at a high level, and the upper and lower tube drives of the other phase bridge arms are maintained at a low level; When it is necessary to control the transformer circuit to enter the full-bridge mode: the upper and lower tube driving signals of two-phase bridge arms of the multi-phase switch circuit are complementary, and the phases between the two-phase bridge arms are staggered by 180 degrees, and the upper and lower tube driving signals of the other phase bridge arms are maintained at a low level; When it is necessary to control the transformer to enter the three-interleaved mode: the upper and lower tube driving signals of each phase bridge arm of the multi-phase switching circuit are complementary, and the phases between adjacent phase bridge arms are staggered by 2π / M degrees, where M represents the number of phases of the multi-phase switching circuit.

8. A multi-interleaved resonant converter, characterized in that: It comprises a multi-phase switching circuit, a transformer circuit, a sampling circuit, and a control circuit for generating waves to control the multi-phase switching circuit, wherein the control circuit is used to execute the method according to any one of claims 1 to 7.

9. The method according to claim 8, characterized in that The multi-phase switching circuit is a three-phase switching circuit, and the three-phase switching circuit includes multi-phase bridge arms connected in parallel, and each phase bridge arm includes upper and lower tubes connected in series.

10. A controller, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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