Synchronous rectification control method, device, computer program and readable storage medium

Abstract

The present application discloses a synchronous rectification control method, device, computer program and readable storage medium, which is applied to a CLLC resonant circuit, and includes: obtaining the output voltage value and output current value of the CLLC resonant circuit, and determining the control frequency of the secondary switch tube based on the output voltage value and the output current value; obtaining the current resonant frequency of the CLLC resonant circuit, and determining the maximum conduction time of the secondary switch tube based on the magnitude relationship with the sum of the current resonant frequency and the frequency deviation of the CLLC resonant circuit; determining the turn-on time and turn-off time of the secondary switch tube according to the absolute value of the secondary resonant cavity current; and performing synchronous rectification control on the secondary switch tube based on the working parameters of the secondary switch tube. By adopting the present application, there is no need to design an additional dedicated synchronous rectification circuit, thereby reducing the hardware cost on the OBC.

Description

Technical Field

[0001] The present application relates to the field of on-board chargers for electric vehicles, and in particular to a synchronous rectification control method, device, computer program and readable storage medium. Background Art

[0002] In the field of on-board chargers (OBC) for electric vehicles, the isolated bidirectional resonant converter CLLC topology has been widely used for its advantages of wide range, high efficiency, bidirectional energy flow, and high frequency. In the actual selection process of the switch tube in the CLLC resonant circuit, the primary switch tube usually uses a metal-oxide semiconductor field-effect transistor (MOSFET), referred to as a metal-oxide-semiconductor field-effect transistor or MOS tube, and the secondary switch tube usually uses silicon carbide (SiC) to meet the output high voltage requirements. Since the conduction voltage drop of silicon carbide (SiC) is much greater than that of MOS tube, when the CLLC is working in the forward direction, when the primary MOS tube is turned on, the secondary side needs to be synchronously rectified to reduce the loss of silicon carbide (SiC) on the secondary side and meet the temperature rise requirements.

[0003] In the prior art, the commonly used schemes for CLLC secondary-side synchronous rectification are: 1) detecting the current size and direction of the secondary-side resonant cavity to control the time and direction of synchronous rectification conduction; 2) detecting the secondary-side silicon carbide (SiC) drain-source (DS) voltage to control the time and direction of synchronous rectification conduction.

[0004] However, the synchronous rectification solutions in the prior art all require the design of additional hardware synchronous rectification detection circuits to achieve synchronous rectification, which will increase the size of the OBC and the corresponding hardware cost. Summary of the invention

[0005] The embodiments of the present application provide a synchronous rectification control method, device, computer program and readable storage medium, which can perform synchronous rectification based on the frequency characteristics of the CLLC resonant circuit itself, without the need to design additional dedicated synchronous rectification circuits, thereby reducing the hardware cost on the OBC.

[0006] In a first aspect, the present application provides a synchronous rectification control method, which includes: obtaining an output voltage value Vout and an output current value Iout of the CLLC resonant circuit, and determining a control frequency freq of a secondary switch tube based on the output voltage value and the output current value; obtaining a current resonant frequency fr of the CLLC resonant circuit, and determining a maximum on-time Ton of the secondary switch tube based on a magnitude relationship between the control frequency freq of the secondary switch tube and the sum of the current resonant frequency fr and a frequency deviation △f of the CLLC resonant circuit; determining a turn-on moment Ton_time of the secondary switch tube according to an absolute value Ict of a secondary resonant cavity current; and determining a turn-off moment Toff_time of the secondary switch tube according to the absolute value Ict of the secondary resonant cavity current and the maximum on-time Ton; and performing synchronous rectification control on the secondary switch tube based on the control frequency freq of the secondary switch tube, the maximum on-time Ton, the turn-on moment Ton_time and the turn-off moment Toff_time.

[0007] From the perspective of technical effects, the embodiments of the present application can determine the maximum on-time Ton of the secondary switch tube, as well as the turn-on time Ton_time and the turn-off time Toff_time of the secondary switch tube based on the frequency characteristics of the resonant circuit (i.e., the current resonant frequency fr), and then perform synchronous rectification control on the secondary switch tube based on the maximum on-time Ton, as well as the turn-on time Ton_time and the turn-off time Toff_time of the secondary switch tube, without the need for a hardware synchronous rectification circuit, which can effectively save the corresponding hardware cost.

[0008] In a feasible implementation manner, the maximum on-time Ton of the secondary switch tube is determined based on the relationship between the control frequency freq of the secondary switch tube and the sum of the current resonant frequency fr and the frequency deviation △f of the CLLC resonant circuit, including: when the control frequency freq of the secondary switch tube is less than the sum of the current resonant frequency fr and the frequency deviation △f, the maximum on-time Ton is calculated based on the current resonant frequency fr, the duty cycle and the frequency deviation △f; or when the control frequency freq of the secondary switch tube is greater than or equal to the sum of the current resonant frequency fr and the frequency deviation △f, the maximum on-time Ton is calculated based on the control frequency freq of the secondary switch tube.

[0009] From the technical effect point of view, the present application directly calculates the maximum on-time of the secondary switch tube through the current resonant frequency fr and the secondary switch tube control frequency freq, thereby providing a corresponding basis for the subsequent calculation of the working parameters of the secondary switch tube.

[0010] In a feasible implementation manner, the frequency deviation △f is calculated by the maximum current resonant frequency and the current resonant frequency; wherein the maximum current resonant frequency is calculated based on the inductance value of the resonant inductor in the CLLC resonant circuit, the capacitance value of the resonant capacitor, the deviation coefficient of the resonant inductor, the deviation coefficient of the resonant capacitor, and the turns ratio of the transformer in the CLLC resonant circuit.

[0011] In a feasible implementation manner, the turn-on time Ton_time of the secondary side switch tube is determined according to the absolute value Ict of the secondary side resonant cavity current, including: when the absolute value Ict of the secondary side resonant cavity current is greater than the preset secondary side turn-on current value Ion_set, the turn-on time Ton_time is calculated based on the turn-on delay Ton_delay of the CLLC resonant circuit; or when the absolute value Ict of the secondary side resonant cavity current is less than or equal to the preset secondary side turn-on current value Ion_set, the secondary side switch tube remains in the off state.

[0012] In a feasible implementation manner, the turn-off moment Toff_time of the secondary side switch tube is determined according to the absolute value Ict of the secondary side resonant cavity current and the maximum on-time Ton, including: when the absolute value Ict of the secondary side resonant cavity current is greater than the preset secondary side turn-off current value Ioff_set, the turn-off moment Toff_time is calculated based on the turn-off delay Toff_delay of the CLLC resonant circuit; or when the absolute value Ict of the secondary side resonant cavity current is less than or equal to the preset secondary side turn-off current value Ioff_set, the secondary side switch tube remains in the on state.

[0013] From the technical effect point of view, the present application can directly calculate the turn-on time and turn-off time of the secondary side switch tube through the maximum turn-on time Ton of the secondary side switch tube and the absolute value of the secondary side resonant cavity current Ict, thereby providing a corresponding control basis for subsequent pulse width modulation (ie, synchronous rectification control).

[0014] In a feasible implementation manner, the preset secondary side turn-on current value Ion_set is in the range of [3A, 10A].

[0015] In a feasible implementation manner, the control frequency of the secondary switch tube is determined based on the output voltage value and the output current value, including: in the frequency modulation mode and the phase shift mode, the frequency and phase of the primary switch tube are determined based on the output voltage value Vout and the output current value Iout, and the control frequency freq of the secondary switch tube is determined based on the frequency and phase of the primary switch tube; or in the asymmetric width modulation mode, the frequency, phase and duty cycle of the primary switch tube are determined based on the output voltage value Vout and the output current value Iout, and the control frequency freq of the secondary switch tube is determined based on the frequency, phase and duty cycle of the primary switch tube.

[0016] From the technical effect point of view, the present application can directly calculate the control frequency of the secondary side switch tube in different working modes through the output voltage value and the output current value, and provide corresponding control parameters for subsequent synchronous rectification control.

[0017] In a feasible implementation manner, the conduction voltage drop of the primary switch tube is not equal to the conduction voltage drop of the secondary switch tube.

[0018] In a second aspect, the present application provides a synchronous rectification control device, which includes: an acquisition unit, used to acquire an output voltage value Vout and an output current value Iout of the CLLC resonant circuit, and used to acquire a current resonant frequency fr of the CLLC resonant circuit; a processing unit, used to determine a control frequency freq of a secondary switch tube according to the output voltage value Vout and the output current value Iout, and used to determine a maximum on-time Ton of the secondary switch tube according to a magnitude relationship between the control frequency freq of the secondary switch tube and the sum of the current resonant frequency fr and a frequency deviation △f of the CLLC resonant circuit; determine a turn-on moment Ton_time of the secondary switch tube according to an absolute value Ict of a secondary resonant cavity current; and determine a turn-off moment Toff_time of the secondary switch tube according to the absolute value Ict of the secondary resonant cavity current and the maximum on-time Ton; a control unit, used to perform synchronous rectification control on the secondary switch tube according to the control frequency freq of the secondary switch tube, the maximum on-time Ton, the turn-on moment Ton_time and the turn-off moment Toff_time.

[0019] In a third aspect, the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed, the method described in any one of the first aspects above is implemented.

[0020] In a fourth aspect, the present application provides a computer program, which includes instructions. When the computer program is executed, the method described in any one of the first aspects above is implemented. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The following is an introduction to the drawings used in the embodiments of the present application.

[0022] Figure 1 is a topological diagram of a CLLC in an embodiment of the present application;

[0023] Figure 2 It is a flow chart of a synchronous rectification control method in an embodiment of the present application;

[0024] Figure 3 It is a schematic diagram of a calculation process of the maximum on-time of a secondary side switch tube in an embodiment of the present application;

[0025] Figure 4 It is a schematic diagram of a calculation process of the turn-on time of a secondary side switch tube in an embodiment of the present application;

[0026] Figure 5 It is a schematic diagram of a calculation process of the turn-off time of a secondary side switch tube in an embodiment of the present application;

[0027] Figure 6 This is a schematic diagram of a synchronous rectification control process in an embodiment of the present application;

[0028] Figure 7 It is a structural schematic diagram of a synchronous rectification control device in an embodiment of the present application;

[0029] Figure 8 It is a schematic diagram of the hardware structure of a synchronous rectification control device in an embodiment of the present application. DETAILED DESCRIPTION

[0030] The following is a description of the embodiments of the present application in conjunction with the drawings in the embodiments of the present application. The terms "first", "second", "third" and "fourth" in the specification and claims of the present application and the drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The phrase does not necessarily refer to the same embodiment at various locations in the specification, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0031] See also Figure 1 , Figure 1 FIG. 1 is a topological diagram of a CLLC in the prior art. Figure 1 As shown, the CLLC resonant circuit includes a primary side, a secondary side and a transformer T1.

[0032] The primary side includes a resonant capacitor Cr1, a resonant inductor Lr, an excitation inductor Lm, a capacitor Cr3 and four power switch tubes; wherein the excitation inductor Lm is connected in parallel with the primary side of the transformer, and then connected in series with the resonant inductor Lr and the resonant capacitor Cr1. The soft switch structure composed of four power switch tubes is connected to the bus voltage, and the capacitor Cr3 is also connected to both ends of the bus voltage. Among them, the bus voltage can be provided by a charging pile, etc., and this application does not limit this. The primary side of the CLLC resonant circuit can be a component such as an on-board charger OBC of an electric vehicle.

[0033] The secondary side includes a resonant capacitor Cr2, a capacitor Cr4 and four power switch tubes. The resonant capacitor Cr2 is connected in series with the secondary side of the transformer T1, and the structure formed by the series connection is connected to the four switch tubes. The capacitor Cr4 is connected in parallel to the two ends of the soft switch composed of the four power switch tubes. The load of the secondary side can be a device such as a power battery.

[0034] Among them, the power switch tubes of the primary side and the secondary side mentioned above can be MOS tubes or switch tubes such as silicon carbide SiC, which is not limited in this application.

[0035] See also Figure 2 , Figure 2 FIG. 1 is a flow chart of a synchronous rectification control method in an embodiment of the present application. Figure 2 As shown, method 200 includes step S210, step S220, step S230 and step S240.

[0036] Step S210: obtaining an output voltage value Vout and an output current value Iout of the CLLC resonant circuit, and determining a control frequency freq of a secondary side switch tube based on the output voltage value and the output current value.

[0037] Specifically, the operating parameters of the primary switch tube are determined according to the obtained output voltage value Vout and the output current value Iout, and the control frequency freq of the secondary switch tube is calculated based on the operating parameters of the primary switch tube.

[0038] Among them, when the CLLC resonant circuit is in different working modes, the control frequency freq of the switch tube is determined in different ways, which may specifically include the following two methods:

[0039] (1) FM mode or phase shift mode

[0040] Compare the preset output voltage target value and the output voltage value Vout, as well as the preset output current target value and the output current value Iout, and obtain the operating parameters of the primary switch through calculation and competition of the voltage and current loop controllers. The operating parameters at this time include frequency and phase; determine the control frequency freq of the secondary switch based on the frequency and phase of the primary switch.

[0041] (2) Asymmetric Width Adjustment Mode

[0042] Compare the size relationship between the preset output voltage target value and the output voltage value Vout, as well as the size relationship between the preset output current target value and the output current value Iout, and obtain the operating parameters of the primary switch through calculation and competition of the voltage and current loop controllers. The operating parameters at this time include frequency, phase and duty cycle; determine the control frequency freq of the secondary switch tube based on the frequency, phase and duty cycle of the primary switch tube.

[0043] Optionally, the phase of the secondary side switch tube may be fixed at 180°, and the duty cycle may be fixed at 50%.

[0044] Among them, the above-mentioned output voltage target value and output current target value are respectively the output voltage set value and the output current set value, which are the rated voltage value and the rated current value issued according to the battery management requirements of the vehicle.

[0045] Among them, the operation and competition of the above-mentioned voltage and current loop controllers specifically include: tracking the above-mentioned output voltage target value and / or output current target value through the vehicle automatic feedback control system to achieve system stability. During the tracking process, the real-time frequency and phase are the frequency and phase of the primary side switch tube.

[0046] After determining the operating parameters of the primary switch tube, based on the topological characteristics of the CLLC circuit, that is, the primary and secondary switch tube frequencies are equal, the operating parameters of the secondary switch tube, that is, frequency, phase and duty cycle, etc., are determined.

[0047] Step S220: Obtain the current resonant frequency fr of the CLLC resonant circuit, and determine the maximum on-time Ton of the secondary switch tube based on the control frequency freq of the secondary switch tube and the relationship between the current resonant frequency fr, the duty cycle and the sum of the frequency deviation Δf of the CLLC resonant circuit.

[0048] See also Figure 3 , Figure 3 Schematic diagram of the calculation process of the maximum on-time Ton in the embodiment of the present application. Figure 3 As shown, the calculation process of the maximum on-time Ton can be divided into two cases:

[0049] (a) The control frequency freq of the secondary switch is less than the sum of the current resonant frequency fr and the frequency deviation △f of the CLLC resonant circuit

[0050] In this case, the maximum on-time Ton is calculated by the current resonant frequency fr and the frequency deviation Δf, as shown in formula (1):

[0051]

[0052] Among them, K ton is the duty cycle, which is used to characterize the conduction time in a switching cycle or the total time of a switching cycle, and can be set to a default value of 0.5. The current resonant frequency fr is an inherent parameter of the resonant circuit, which can be calculated by formula (2).

[0053] Wherein, the frequency deviation △f is calculated by the maximum current resonant frequency and the current resonant frequency; wherein, the maximum current resonant frequency is calculated based on the inductance value of the resonant inductor in the CLLC resonant circuit, the capacitance value of the resonant capacitor, the deviation coefficient of the resonant inductor, the deviation coefficient of the resonant capacitor, and the turns ratio of the transformer in the CLLC resonant circuit.

[0054] Specifically, the frequency deviation Δf of the CLLC resonant circuit is a resonant frequency deviation caused by the deviation of hardware parameters within a reasonable range, which can be calculated by formula (3) and formula (4).

[0055]

[0056] Among them, Lr is the resonant inductor; Cr1 is the resonant capacitor of the primary side; Lm is the excitation inductor; n is the turns ratio of the transformer; Cr2 is the resonant capacitor of the secondary side.

[0057]

[0058] Δf=f max -f r (4)

[0059] Where fmax is the maximum current resonant frequency that can be achieved when the hardware parameters are within a reasonable range of deviation; ε Lr is the deviation coefficient of the resonant inductance Lr; Cr1 is the deviation coefficient of the resonant capacitor Cr1; Cr2 is the deviation coefficient of the resonant capacitor Cr2.

[0060] (ii) The control frequency freq of the secondary switch is greater than or equal to the sum of the current resonant frequency fr and the frequency deviation △f of the CLLC resonant circuit

[0061] In this case, the maximum on-time Ton is calculated based on the control frequency freq of the secondary switch tube, as described in formula (2):

[0062]

[0063] Among them, K ton The physical meaning and numerical value are the same as those in formula (1).

[0064] Step S230: determining the turn-on time Ton_time of the secondary switch tube according to the absolute value of the secondary resonant cavity current Ict; and determining the turn-off time Toff_time of the secondary switch tube according to the absolute value of the secondary resonant cavity current Ict and the maximum on-time Ton.

[0065] Specifically, firstly, a preset secondary side turn-on current value Ion_set is obtained, and the turn-on time Ton_time of the secondary side switch tube is determined based on the magnitude relationship between the preset secondary side turn-on current value Ion_set and the absolute value of the secondary side resonant cavity current Ict. Then, the secondary side switch tube is turned on based on the calculated turn-on time Ton_time of the secondary side switch tube.

[0066] The preset secondary side on-current value Ion_set is the threshold for turning on the secondary side switch tube during synchronous rectification, that is, when the current value is greater than or equal to Ion_set, the secondary side switch tube is turned on. Optionally, the preset secondary side on-current value Ion_set is greater than zero, and can usually be set to any value between 3A-10A.

[0067] See also Figure 4 , Figure 4 Schematic diagram of the calculation flow of the secondary switch opening time in the embodiment of the present application. Figure 4 As shown, the calculation of the opening time Ton_time can be divided into two cases:

[0068] (I) The absolute value of the secondary resonant cavity current Ict is greater than the preset secondary turn-on current value Ion_set

[0069] In this case, the turn-on time Ton_time is calculated based on the turn-on delay Ton_delay of the CLLC resonant circuit, as shown in formula (6):

[0070] Ton_time=0+Ton_delay (6)

[0071] Among them, the turn-on delay Ton_delay of the CLLC resonant circuit is the inherent rise delay of the driver chip.

[0072] (ii) The absolute value of the secondary resonant cavity current Ict is less than or equal to the preset secondary turn-on current value Ion_set

[0073] In this case, the secondary side switch is not allowed to turn on, that is, it always remains in the off state.

[0074] The calculation process of the secondary switch tube turn-off time Toff_time is as follows: first, the preset secondary switch-on current value Ion_set is obtained, and the turn-off time Toff_time of the secondary switch tube is determined based on the magnitude relationship between the preset secondary switch-on current value Ion_set and the absolute value of the secondary resonant cavity current Ict. Then, the secondary switch tube is turned off based on the calculated turn-off time Toff_time of the secondary switch tube.

[0075] See also Figure 5 , Figure 5 Schematic diagram of the calculation process of the secondary switch off time in the embodiment of the present application. Figure 5 As shown, the calculation of the turn-off time Toff_time can be divided into two cases:

[0076] (I) The absolute value of the secondary resonant cavity current Ict is greater than the preset secondary turn-on current value Ion_set

[0077] In this case, the turn-off time Toff_time is calculated based on the turn-off delay Toff_delay of the CLLC resonant circuit, as shown in formula (7):

[0078] Toff_time=Ton-Toff_delay (7)

[0079] Among them, the turn-off delay Toff_delay of the CLLC resonant circuit is the inherent falling edge delay of the driver chip.

[0080] (ii) The absolute value of the secondary resonant cavity current Ict is less than or equal to the preset secondary turn-on current value Ion_set

[0081] In this case, the driver is turned off, that is, the secondary side switch tube is not allowed to be turned off and remains in the on state.

[0082] Step S240: performing synchronous rectification control on the secondary switch tube based on the control frequency freq of the secondary switch tube, the maximum on-time Ton, the on-time Ton_time and the off-time Toff_time.

[0083] Specifically, after calculating the maximum on-time Ton, turn-on moment Ton_time and turn-off moment Toff_time of the secondary switch tube, pulse width modulation (PWM) can be performed on the secondary switch tube based on the control frequency freq (phase fixed at 180°, duty cycle fixed at 50%), the maximum on-time Ton, turn-on moment Ton_time and turn-off moment Toff_time of the secondary switch tube to perform synchronous rectification control.

[0084] Optionally, the conduction voltage drop of the primary switch tube is not equal to the conduction voltage drop of the secondary switch tube.

[0085] Specifically, the conduction voltage drop of the primary switch tube may be greater than the conduction voltage drop of the secondary switch tube, or the conduction voltage drop of the primary switch tube may be less than the conduction voltage drop of the secondary switch tube.

[0086] See also Figure 6 , Figure 6 Schematic diagram of a synchronous rectification control process in an embodiment of the present application. Figure 6 As shown, the sampling module in the data processor can directly collect the output current value Iout and the output voltage value Vout of the secondary side of the CLLC resonant circuit, and then calculate the control frequency of the primary side switch tube and the control frequency of the secondary side switch tube based on the relationship between the output voltage value Vout and the output voltage target value Vout_ref and / or based on the relationship between the output current value Iout and the output current target value Iout_ref; and calculate the maximum conduction time Ton of the secondary side switch tube based on the control frequency of the secondary side switch tube. Then, the absolute value Ict of the secondary side resonant cavity current and the preset secondary side turn-on current value Ion_set are compared by the internal op amp comparator, and the turn-on time and turn-off time of the secondary side switch tube are calculated based on the comparison result, as well as the circuit frequency characteristics (i.e., the current resonant frequency fr) and the hardware drive characteristics (turn-on delay Ton_delay and turn-off delay Toff_delay). Finally, the working parameters of the primary side switch tube (control frequency, phase, etc.) and the working parameters of the secondary side switch tube (control frequency freq, maximum on-time Ton, turn-on time Ton_time and turn-off time Toff_time, etc.) are respectively input into the primary side PWM and the secondary side PWM for synchronous rectification control.

[0087] Among them, the calculation process of the above-mentioned sampled related primary side switch tube operating parameters and secondary side switch tube operating parameters can be obtained by executing software by a data processor, without the need for additional dedicated hardware synchronous rectification circuit, effectively saving hardware costs.

[0088] See also Figure 7 , Figure 7Schematic diagram of the structure of a synchronous rectification control device in an embodiment of the present application. Figure 7 As shown, the synchronous rectification control device includes: an acquisition unit 701, a processing unit 702 and a control unit 703. Among them,

[0089] The acquisition unit 701 is used to acquire the output voltage value Vout and the output current value Iout of the CLLC resonant circuit, and to acquire the current resonant frequency fr of the CLLC resonant circuit.

[0090] The processing unit 702 is used to determine the control frequency freq of the secondary switch tube according to the output voltage value Vout and the output current value Iout, and to determine the maximum on-time Ton of the secondary switch tube according to the relationship between the control frequency freq of the secondary switch tube and the sum of the current resonant frequency fr and the frequency deviation △f of the CLLC resonant circuit; determine the turn-on time Ton_time of the secondary switch tube according to the absolute value Ict of the secondary resonant cavity current; and determine the turn-off time Toff_time of the secondary switch tube according to the absolute value Ict of the secondary resonant cavity current and the maximum on-time Ton.

[0091] The control unit 703 is used to perform synchronous rectification control on the secondary side switch tube according to the control frequency freq of the secondary side switch tube, the maximum on-time Ton, the on-time Ton_time and the off-time Toff_time.

[0092] Specifically, the specific working process of the synchronous rectification control device can correspond to the corresponding process in the aforementioned synchronous rectification control method, which will not be repeated here.

[0093] See also Figure 8 , Figure 8 Schematic diagram of the hardware structure of a synchronous rectification control device in an embodiment of the present application. Figure 8 As shown, the synchronous rectification control device includes a communication interface 801 , a processor 802 , a memory 803 , and at least one communication bus 804 for connecting the communication interface 801 , the processor 802 , and the memory 803 .

[0094] The memory 803 includes, but is not limited to, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), or portable read-only memory (CD-ROM), and the memory 803 is used for related instructions and data.

[0095] The communication interface 801 is used to receive and send data.

[0096] The processor 802 may be one or more central processing units (CPUs). When the processor 802 is a CPU, the CPU may be a single-core CPU or a multi-core CPU.

[0097] The processor 802 in the synchronous rectification control device is used to read one or more program codes stored in the memory 803 and execute the following steps: Figure 2 Any of the methods described in the Examples.

[0098] The embodiment of the present application also provides a computer-readable storage medium, in which a computer program is stored. When the computer-readable storage medium is run on a terminal, the method flow shown in the above method embodiment is implemented.

[0099] The embodiment of the present application also provides a computer program product. When the computer program product is run on a terminal, the method flow shown in the above method embodiment is implemented.

[0100] It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0101] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus random access memory (Direct Rambus RAM, DR RAM).

[0102] It should be noted that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware component, the memory (storage module) is integrated in the processor.

[0103] It should be noted that the memory described herein is intended to include, but is not limited to, these and any other suitable types of memory.

[0104] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0105] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0106] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described devices and units can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0107] In the several embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic. For example, the division of units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0108] The units described above as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0109] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0110] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0111] The steps in the method of the embodiment of the present application can be adjusted in order, combined and deleted according to actual needs.

[0112] The modules in the device of the embodiment of the present application can be merged, divided and deleted according to actual needs.

[0113] As described above, the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A synchronous rectification control method, applied to a CLLC resonant circuit, characterized in that: The method comprises: Acquire an output voltage value and an output current value of the CLLC resonant circuit, and determine a control frequency of a secondary-side switch tube based on the output voltage value and the output current value; Acquire the current resonant frequency of the CLLC resonant circuit, and determine the maximum on-time of the secondary switch tube based on the relationship between the control frequency of the secondary switch tube and the sum of the current resonant frequency and the frequency deviation of the CLLC resonant circuit; Determining the turn-on time of the secondary side switch tube according to the absolute value of the secondary side resonant cavity current; and determining the turn-off time of the secondary side switch tube according to the absolute value of the secondary side resonant cavity current and the maximum conduction time; Synchronous rectification control is performed on the secondary side switch tube based on the control frequency of the secondary side switch tube, the maximum on-time, the turn-on time and the turn-off time.

2. The method according to claim 1, characterized in that The determining the maximum on-time of the secondary switch tube based on the control frequency of the secondary switch tube and the sum of the current resonant frequency and the frequency deviation of the CLLC resonant circuit comprises: When the control frequency of the secondary switch tube is less than the sum of the current resonant frequency and the frequency deviation, the maximum on-time is calculated based on the current resonant frequency, the duty cycle and the frequency deviation; or When the control frequency of the secondary switch tube is greater than or equal to the sum of the current resonant frequency and the frequency deviation, the maximum on-time is calculated based on the control frequency of the secondary switch tube.

3. The method according to claim 2, characterized in that The frequency deviation is calculated by using the maximum current resonance frequency and the current resonance frequency; Among them, the maximum current resonant frequency is calculated based on the inductance value of the resonant inductor, the capacitance value of the resonant capacitor, the deviation coefficient of the resonant inductor, the deviation coefficient of the resonant capacitor, and the turns ratio of the transformer in the CLLC resonant circuit.

4. The method according to any one of claims 1 to 3, characterized in that The step of determining the turn-on time of the secondary side switch tube according to the absolute value of the secondary side resonant cavity current comprises: When the absolute value of the secondary side resonant cavity current is greater than a preset secondary side turn-on current value, calculating the turn-on time based on the turn-on delay of the CLLC resonant circuit; or When the absolute value of the secondary side resonant cavity current is less than or equal to the preset secondary side turn-on current value, the secondary side switch tube remains in the off state.

5. The method according to claim 1, characterized in that The step of determining the turn-off time of the secondary side switch tube according to the absolute value of the secondary side resonant cavity current and the maximum on-time includes: When the absolute value of the secondary side resonant cavity current is greater than a preset secondary side turn-on current value, calculating the turn-off time based on the turn-off delay of the CLLC resonant circuit; or When the absolute value of the secondary side resonant cavity current is less than or equal to a preset secondary side turn-on current value, the secondary side switch tube remains in the turn-on state.

6. The method according to claim 5, characterized in that The preset secondary side turn-on current value range is [3A, 10A].

7. The method according to claim 1, characterized in that The determining the control frequency of the secondary side switch tube based on the output voltage value and the output current value includes: In the frequency modulation mode and the phase shift mode, the frequency and phase of the primary switch tube are determined based on the output voltage value and the output current value, and the control frequency of the secondary switch tube is determined based on the frequency and phase of the primary switch tube; or In the asymmetric width modulation mode, the frequency, phase and duty cycle of the primary switch tube are determined based on the output voltage value and the output current value, and the control frequency of the secondary switch tube is determined based on the frequency, phase and duty cycle of the primary switch tube.

8. A synchronous rectification control device, applied to a CLLC resonant circuit, characterized in that: The device comprises: an acquisition unit, used to acquire an output voltage value and an output current value of the CLLC resonant circuit, and to acquire a current resonant frequency of the CLLC resonant circuit; A processing unit, used to determine the control frequency of the secondary switch tube according to the output voltage value and the output current value, and to determine the maximum on-time of the secondary switch tube according to the relationship between the control frequency of the secondary switch tube and the sum of the current resonant frequency and the frequency deviation of the CLLC resonant circuit; to determine the turn-on time of the secondary switch tube according to the absolute value of the secondary resonant cavity current; and to determine the turn-off time of the secondary switch tube according to the absolute value of the secondary resonant cavity current and the maximum on-time; A control unit is used to perform synchronous rectification control on the secondary side switch tube according to the control frequency of the secondary side switch tube, the maximum conduction time, the turn-on time and the turn-off time.

9. A computer-readable storage medium storing a computer program, wherein when the computer program is executed, the method according to any one of claims 1 to 7 is implemented.

10. A computer program, characterized in that The computer program comprises instructions, and when the computer program is executed, the method according to any one of claims 1 to 7 is implemented.

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