Resonant converter control method and system

Abstract

The invention discloses a resonant converter control method and system. The resonant converter control method comprises the following steps: in each switching period, determining a target power value according to an input power control quantity and a compensation quantity corresponding to a bridge arm; determining a target slope control quantity corresponding to a counter corresponding to the switching transistor according to the target power value, the input voltage, circuit parameters of the resonant converter and a current working mode of the full-bridge inversion module; determining a comparison threshold according to the target slope control quantity, a current count value of a counter corresponding to the switch transistor and a direct current offset voltage of a resonant capacitor corresponding to the current working mode; wherein the counter starts counting by taking the direct-current offset voltage as an initial value in each switching period until the actual voltage of the resonant capacitor is equal to a comparison threshold value; and determining a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switching transistor according to the control signal. According to the technical scheme, the output of the resonant converter can be well controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of resonant converters, and in particular to a resonant converter control method and system. Background Art

[0002] DC-DC converters mostly use Buck circuits or flyback circuits. By controlling the duty cycle of the control signal of the switching transistor in the DC converter, the output gain of the DC converter can be controlled. However, it is difficult for Buck circuits or flyback circuits to achieve zero voltage and zero current switching, and they are not suitable for high-frequency design. Resonant DC converters are easy to achieve zero voltage and zero current switching, which is convenient for high-frequency design. Resonant DC converters can control the output gain by controlling the frequency of the control signal of the switching transistor. However, its high conversion efficiency operating frequency range is relatively narrow. When its input and output voltage ranges are wide, the conversion efficiency is low.

[0003] The full-bridge resonant converter includes a full-bridge conversion circuit, and the operating modes of the full-bridge conversion circuit include a full-bridge mode and a half-bridge mode. At the same switching frequency, the conversion gain of the full-bridge mode is twice that of the half-bridge mode. When the operating mode of the full-bridge conversion circuit is switched, the output voltage needs to be kept stable. For example, the papers Modulation Transition Methods Based on Trajectory Control for LLC Resonant Converters Operating in Wide Input-and / or Output-Voltage Range (IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL.37, NO.12, DECEMBER 2022) and Wide Voltage Input Full Bridge (FB) / Half Bridge (HB) Morphing-Based LLC DC–DC Converter Using Numerical Optimal Trajectory Control (IEEE TRANSACTIONS ON INDUSTRIAL ELECTRONICS, VOL.70, NO.4, APRIL 2023) disclose optimal trajectory control methods based on direct frequency or duty cycle control, that is, controlling the switching frequency of the switching transistor in the full-bridge conversion circuit or the duty cycle of the control signal of the switching transistor to adjust the output voltage and keep the output voltage stable.

[0004] However, controlling the switching frequency of the switching transistor in the full-bridge conversion circuit or the duty cycle of the control signal of the switching transistor requires complex calculations, and the accuracy of the parameters of the resonant element is high. In addition, the dynamic performance of the control is poor when the switching frequency is directly controlled. For example, in the paper Bang-Bang Charge Control for LLC Resonant Converters (IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL.30, NO.2, FEBRUARY 2015), in order to obtain higher dynamic performance of the resonant DCDC converter, a current-type control method based on the feedback of the resonant cavity state (the voltage of the resonant capacitor in the resonant circuit or the current of the resonant capacitor) is adopted, that is, the switching moment of the switching transistor is controlled by the feedback voltage or feedback current of the resonant capacitor in the resonant circuit, thereby controlling the output voltage of the resonant converter. However, these methods cannot be directly used for transient control of the resonant topology mode switching process, and the transient control performance of the resonant converter during operation is poor, and there is a problem that the output of the resonant converter cannot be well controlled. Summary of the invention

[0005] The present invention provides a resonant converter control method and system to solve the problems that the existing resonant converter control method has poor transient control performance during the operation of the resonant converter, cannot achieve transient control of the mode switching process, and cannot better control the output of the resonant converter.

[0006] According to one aspect of the present invention, a resonant converter control method is provided, wherein the resonant converter comprises a full-bridge inverter module, a resonant conversion module and a rectifier module; the full-bridge inverter module is connected to the resonant conversion module, and the resonant conversion module is connected to the rectifier module; the full-bridge inverter module comprises at least two bridge arms; the resonant conversion module comprises a resonant capacitor; the method is executed by a resonant converter control system; the control system is connected to a control electrode of a switch transistor of the bridge arm, and the control system comprises a counter; the method comprises:

[0007] In each switching cycle, a target power value is determined according to an input power control amount and a compensation amount corresponding to the bridge arm;

[0008] Determining a target slope control amount corresponding to a counter corresponding to the switching transistor according to the target power value, the input voltage, the circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module; wherein the working mode includes a full-bridge mode or a half-bridge mode;

[0009] Determine a comparison threshold value according to the target slope control amount, the current count value of the counter corresponding to the switching transistor and the DC offset voltage of the resonant capacitor corresponding to the current working mode; wherein the counter starts counting with the DC offset voltage as the initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold value;

[0010] A control signal is determined according to the actual voltage of the resonant capacitor and the comparison threshold, and the switch transistor is controlled according to the control signal.

[0011] Optionally, when the working mode of the full-bridge inverter module is switched, the method further includes:

[0012] The half-bridge operating mode of the full-bridge inverter module is enabled or disabled, and the DC offset voltage of the resonant capacitor is updated according to the switched operating mode, and the target slope control amount is updated according to the switched operating mode.

[0013] Optionally, before determining the target power value according to the input power control amount and the compensation amount corresponding to the bridge arm, the method further includes:

[0014] Inputting the output voltage of the resonant converter, the reference voltage and the first feedback coefficient into an output voltage closed-loop controller to obtain a first deviation value;

[0015] Obtaining a power feedforward value according to the output voltage, the output current of the resonant converter, the first feedback coefficient and the second feedback coefficient, and obtaining an initial target input power value according to the power feedforward value and the first deviation value;

[0016] Inputting the first input voltage, the second input voltage and the sampling coefficient into the input voltage equalizing closed-loop controller to obtain a second deviation value; wherein the full-bridge inverter module includes a first bridge arm and a second bridge arm, the first input voltage is the input voltage of the first bridge arm, and the second input voltage is the input voltage of the second bridge arm;

[0017] The input power control amount is determined according to the initial target input power value, the second deviation value and a normalization coefficient.

[0018] Optionally, determining the target slope control amount corresponding to the counter corresponding to the switching transistor according to the target power value, the input voltage, the circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module includes:

[0019] Determine the change slope control amount corresponding to each bridge arm according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor, and determine the full-bridge slope control amount and the half-bridge slope control amount according to the change slope control amount;

[0020] The full-bridge slope control amount or the half-bridge slope control amount is determined as the target slope control amount according to the current working mode of the full-bridge inverter module.

[0021] Optionally, determining a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switch transistor of the bridge arm according to the control signal comprises:

[0022] When the ratio of the actual voltage to the sampling coefficient is less than the comparison threshold, controlling the first target switch transistor in the corresponding bridge arm to be turned on;

[0023] When the ratio of the actual voltage to the sampling coefficient is greater than the comparison threshold, the second target switch transistor in the corresponding bridge arm is controlled to be turned on.

[0024] Optionally, the determining a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switch transistor of the bridge arm according to the control signal, further includes:

[0025] When the ratio of the actual voltage to the sampling coefficient is equal to the comparison threshold corresponding to the first target switch transistor, the first target switch transistor corresponding to the counter is controlled to be turned off, and the second target switch transistor is controlled to be turned on, wherein the control signal of the first target switch transistor is inverted with the control signal corresponding to the second target switch transistor.

[0026] Optionally, determining the target power value according to the input power control amount and the compensation amount corresponding to the bridge arm includes:

[0027] The sum of the input power control amount corresponding to the bridge arm and the compensation amount is used as the target power value corresponding to the bridge arm.

[0028] Optionally, determining the change slope control amount corresponding to each bridge arm according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor includes:

[0029] Dividing the target power value by the input voltage of the corresponding bridge arm and by the capacitance of the resonant capacitor to obtain a first intermediate value;

[0030] The first intermediate value is divided by the sampling coefficient and multiplied by the counting step value to obtain the change slope control amount of the corresponding bridge arm.

[0031] According to another aspect of the present invention, a resonant converter control system is provided, wherein the resonant converter comprises a full-bridge inverter module, a resonant conversion module and a rectifier module; the full-bridge inverter module is connected to the resonant conversion module, and the resonant conversion module is connected to the rectifier module; the full-bridge inverter module comprises at least two bridge arms; the resonant conversion module comprises a resonant capacitor; the control system is connected to the control electrode of the switch transistor of the bridge arm; the control system comprises a counter; the control system comprises:

[0032] A target power value determination module, used to determine the target power value according to the input power control amount and compensation amount corresponding to the bridge arm in each switching cycle;

[0033] a target slope control amount determination module, connected to the target power value determination module, for determining a target slope control amount corresponding to a counter corresponding to the switching transistor according to the target power value, input voltage, circuit parameters of the resonant converter and a current working mode of the full-bridge inverter module; wherein the working mode includes a full-bridge mode or a half-bridge mode;

[0034] a comparison threshold determination module, connected to the target slope control amount determination module, and configured to determine a comparison threshold according to the target slope control amount, a current count value of a counter corresponding to the switching transistor, and a DC offset voltage of the resonant capacitor corresponding to a current working mode; wherein the counter starts counting with the DC offset voltage as an initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold;

[0035] A control module is connected to the comparison threshold determination module, and is used to determine a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and control the switch transistor according to the control signal.

[0036] Optionally, the target power value determination module includes a first adder;

[0037] The first input end of the first adder is connected to the input power control amount, and the second input end of the first adder is connected to the compensation amount; the first adder is used to add the input power control amount and the compensation amount to obtain the target power value.

[0038] The technical solution of the embodiment of the present invention is that in each switching cycle, the target power value is determined according to the input power control amount and compensation amount corresponding to the bridge arm, the target slope control amount corresponding to the counter corresponding to the switching transistor is determined according to the target power value, input voltage, circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module, the comparison threshold can be adjusted according to the target slope control amount, and the switching transistor can be controlled to be turned on or off according to the relationship between the comparison threshold and the actual voltage of the resonant capacitor, thereby adjusting the input power and realizing direct control of the single-cycle input power. In addition, the DC offset voltage of the resonant capacitor corresponding to different working modes is different, so that the determined comparison threshold can be applied to different working modes, thereby realizing switching of different working modes, and even if the working mode is switched, the output voltage of the resonant converter can be better controlled to realize stable output of the output voltage. In addition, the comparison threshold is determined according to the count value of the counter, so that the comparison threshold is a variable value, which can improve the transient control during the working process of the resonant converter and realize better control of the output of the resonant converter.

[0039] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 is a schematic diagram of a circuit structure of a resonant converter provided by an embodiment of the present invention;

[0042] Figure 2 yes Figure 1 A schematic diagram of a first operating mode of a resonant converter;

[0043] Figure 3 yes Figure 1 A schematic diagram of a second operating mode of the resonant converter;

[0044] Figure 4 yes Figure 1 A schematic diagram of a third operating mode of the resonant converter;

[0045] Figure 5 yes Figure 1 A schematic diagram of a fourth operating mode of the resonant converter;

[0046] Figure 6is a flow chart of a resonant converter control method provided by an embodiment of the present invention;

[0047] Figure 7 is a flow chart of another resonant converter control method provided by an embodiment of the present invention;

[0048] Figure 8 is a flow chart of another resonant converter control method provided by an embodiment of the present invention;

[0049] Fig. 9 is a schematic diagram of a time domain operating waveform of a resonant converter provided by an embodiment of the present invention;

[0050] Fig.10 It is a schematic diagram of a state plane operation trajectory of a resonant converter switching from a full-bridge mode to a half-bridge mode provided by an embodiment of the present invention;

[0051] Fig.11 It is a schematic diagram of a state plane operation trajectory of a resonant converter switching from a half-bridge mode to a full-bridge mode provided by an embodiment of the present invention;

[0052] Fig.12 is a structural schematic diagram of a resonant converter control system provided by an embodiment of the present invention;

[0053] Fig.13 is a structural schematic diagram of another resonant converter control system provided by an embodiment of the present invention;

[0054] Fig.14 1 is a schematic diagram of a circuit structure of a full-bridge inverter module provided by an embodiment of the present invention;

[0055] Fig.15 is a schematic diagram of a circuit structure of a resonance module provided by an embodiment of the present invention;

[0056] Fig.16 is a schematic diagram of a circuit structure of another resonance module provided in an embodiment of the present invention;

[0057] Fig.17 1 is a schematic diagram of a circuit structure of a rectifier module provided in an embodiment of the present invention;

[0058] Fig.18 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention;

[0059] Fig.19 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention;

[0060] Fig. 20 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention;

[0061] Fig.21 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention;

[0062] Fig. 22 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention;

[0063] Fig.23 is a waveform diagram of an output voltage and an output current of a resonant converter provided by an embodiment of the present invention;

[0064] Fig.24 is a partial enlarged diagram of the output voltage and output current of the resonant converter provided by an embodiment of the present invention;

[0065] Fig.25 1 is a schematic diagram of operating waveforms of a resonant converter provided by an embodiment of the present invention switching from a half-bridge mode to a full-bridge mode;

[0066] Fig.26 It is a schematic diagram of operating waveforms of a resonant converter provided by an embodiment of the present invention switching from a full-bridge mode to a half-bridge mode. DETAILED DESCRIPTION

[0067] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0068] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof 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 necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0069] In view of the problem that the existing resonant converter control method has poor transient control performance during the operation of the resonant converter and cannot well control the output of the resonant converter, an embodiment of the present invention provides a resonant converter control method. The resonant converter may include a full-bridge inverter module, a resonant conversion module and a rectifier module, the full-bridge inverter module is connected to the resonant conversion module, and the resonant conversion module is connected to the rectifier module. The full-bridge inverter module includes at least two bridge arms. For example, the full-bridge inverter module may include a series full-bridge inverter circuit or a parallel full-bridge inverter circuit, which is not limited in this embodiment. The resonant conversion module may include an LLC resonant network formed by connecting a resonant inductor, an excitation inductor and a resonant capacitor. The resonant conversion module also includes a transformer. The rectifier module includes a series full-bridge rectifier circuit, a parallel full-bridge rectifier circuit or a half-bridge rectifier circuit, etc.

[0070] For example, Figure 1 is a schematic diagram of a circuit structure of a resonant converter provided by an embodiment of the present invention, with reference to Figure 1 The resonant converter includes a full-bridge inverter module 11, a resonant conversion module 12 and a rectifier module 13; the full-bridge inverter module 11 is connected to the resonant conversion module 12, and the resonant conversion module 12 is connected to the rectifier module 13. Figure 1 As shown, the full-bridge inverter module 11 includes a first bridge arm 111 and a second bridge arm 112; the input voltage of the full-bridge inverter module 11 is V in , the first input voltage of the first bridge arm 111 is V in1 , the second input voltage of the second bridge arm 112 is V in1 The output voltage of the resonant converter is V out , output voltage V out Including the first output voltage V out1 and the second output voltage V out2 .

[0071] The first bridge arm 111 includes a first switching transistor Q H1 and the second switching transistor Q L1 The second bridge arm 112 includes a third switch transistor Q H2 and the fourth switching transistor Q L2 , the first switching transistor Q H1 , the second switching transistor Q L1 , the third switching transistor Q H2 and the fourth switching transistor Q L2 The full-bridge inverter module 11 also includes an input filter capacitor, which includes a first input filter capacitor C in1 and the second input filter capacitor C in2 .

[0072] The resonant conversion module 12 includes a resonant inductor L r, Excitation inductance L m , resonant capacitor C r and transformer T, resonant inductor L r , Excitation inductance L m and resonant capacitor C r A resonant cavity (resonant network) is formed. The resonant network is connected to the primary winding of the transformer T. The rectifier module 13 is connected to the secondary winding of the transformer T. The rectifier module 13 includes a first rectifier transistor S H1 , the second rectifier transistor S L1 , the third rectifier transistor S H2 , the fourth rectifier transistor S L2 , the first output capacitor C out1 and the second output capacitor C out2 , the first rectifier transistor S H1 , the second rectifier transistor S L1 , the third rectifier transistor S H2 , the fourth rectifier transistor S L2 , the first output capacitor C out1 and the second output capacitor C out2 The connections form a parallel full-bridge rectifier circuit.

[0073] Figure 2 yes Figure 1 Schematic diagram of the first working mode of the resonant converter, as shown in Figure 2 As shown, when the resonant converter is in the first operating mode, the first switching transistor Q H1 and the third switching transistor Q H2 The second switching transistor Q L1 and the fourth switching transistor Q L2 When the first bridge arm 111 is turned off, the charge is transferred between the port of the first bridge arm 111 and the resonant cavity. That is, the charge is transferred from the input end of the first bridge arm 111 through the first switch transistor Q H1 and resonant cavity, and through the third switching transistor Q H2 and the first input filter capacitor C in1 Return to the input port of the first bridge arm 111 .

[0074] Figure 3 yes Figure 1 Schematic diagram of the second working mode of the resonant converter, such as Figure 3 As shown, when the resonant converter is in the second operating mode, the second switching transistor Q L1 and the fourth switching transistor Q L2 The first switching transistor Q H1 and the third switching transistor Q H2 When turned off, the charge is transferred between the port of the second bridge arm 12 and the resonant cavity.

[0075] Figure 4yes Figure 1 Schematic diagram of the third working mode of the resonant converter, as shown in Figure 4 As shown, when the resonant converter is in the third operating mode, the second switching transistor Q L1 and the third switching transistor Q H2 The first switching transistor Q H1 and the fourth switching transistor Q L2 Turn off, the charge is completely stored in the energy storage element inside the resonant cavity (resonant inductor L r , Excitation inductance L m and resonant capacitor C r ) between.

[0076] Figure 5 yes Figure 1 Schematic diagram of the fourth working mode of the resonant converter, as shown in Figure 5 As shown, the first switching transistor Q H1 and the fourth switching transistor Q L2 The second switching transistor Q L1 and the third switching transistor Q H2 When the switch is turned off, the charge is transferred between the port after the first bridge arm 111 and the second bridge arm 112 are connected in series and the resonant cavity.

[0077] The working modes of the full-bridge inverter module 11 include a full-bridge working mode and a half-bridge working mode. When the full-bridge inverter module 11 works in the full-bridge working mode, the full-bridge inverter module 11 is executed in a cycle in the order of the third working mode, the bridge arm power balance adjustment mode (the first working mode or the second working mode), the fourth working mode, the bridge arm power balance adjustment mode (the first working mode or the second working mode), and the third working mode. Among them, the bridge arm power balance adjustment mode can adjust the input power difference between the first bridge arm 111 and the second bridge arm 112, and can realize the input voltage balance control of the first bridge arm 111 and the second bridge arm 112.

[0078] When the full-bridge inverter module 11 works in the half-bridge working mode, the working mode to be executed can be determined according to the actual application requirements. For example, when the working mode is the high-voltage half-bridge mode of the first bridge arm 111, the full-bridge inverter module 11 is executed in a loop in the order of the fourth working mode, the second working mode, and the fourth working mode. When the working mode is the low-voltage half-bridge mode of the first bridge arm 111, the full-bridge inverter module 11 is executed in a loop in the order of the first working mode, the third working mode, and the first working mode. When the working mode is the high-voltage half-bridge mode of the second bridge arm 112, the full-bridge inverter module 11 is executed in a loop in the order of the fourth working mode, the first working mode, and the fourth working mode. When the working mode is the low-voltage half-bridge mode of the second bridge arm 112, the full-bridge inverter module 11 is executed in a loop in the order of the second working mode, the third working mode, and the second working mode. When the working mode is the high-voltage interleaved half-bridge mode, the full-bridge inverter module 11 is executed cyclically in the order of the fourth working mode, the first working mode, the fourth working mode, the second working mode and the fourth working mode. When the working mode is the low-voltage interleaved half-bridge mode, the full-bridge inverter module 11 is executed cyclically in the order of the first working mode, the third working mode, the second working mode, the third working mode and the first working mode.

[0079] When the resonant converter is running, in order to adapt to different requirements, it may be necessary to change the working mode of the resonant converter, for example, switching from a full-bridge mode to a half-bridge mode, or from a half-bridge mode to a full-bridge mode.

[0080] The embodiment of the present invention provides a resonant converter control method, which is executed by a resonant converter control system; the resonant converter control system is connected to the control electrode of the switch transistor of the bridge arm of the full-bridge inverter module. The resonant converter control system includes a counter, for example, the counter is set in a one-to-one correspondence with the switch transistor.

[0081] Figure 6 is a flow chart of a resonant converter control method provided by an embodiment of the present invention, with reference to Figure 6 , the resonant converter control method includes:

[0082] S101 . In each switching cycle, a target power value is determined according to an input power control amount and a compensation amount corresponding to a bridge arm.

[0083] Wherein, the switching cycle can be the duration between the start of conduction and the next conduction of any switching transistor. Each bridge arm corresponds to an input voltage, and each bridge arm corresponds to an input power. The input power control amount is the control amount for controlling the input power of the bridge arm, and the input power control amount can be obtained by inputting the input electrical parameters and output electrical parameters of the resonant converter into the output voltage closed-loop controller. The compensation amount can adjust the input power control amount to facilitate improving the accuracy of determining the target power value. For example, the compensation amount can be a preset value. Wherein, for example, the input electrical parameters include the input voltage and / or input current of the bridge arm, and the output electrical parameters include the output voltage and / or output current of the resonant converter. The target power value is the target value of the input power of the bridge arm, and each bridge arm corresponds to a target power value.

[0084] Specifically, by determining the target power value according to the input power control amount and compensation amount corresponding to the bridge arm, it is convenient to realize direct control of the input power, thereby eliminating the need to adjust the duty cycle of the control signal of the switching transistor in the bridge arm, eliminating the need for complex calculations, and reducing the requirements for parameter accuracy of the resonant network.

[0085] Furthermore, by determining the target power value in each switching cycle, for example, at the beginning of each switching cycle, the input power of the bridge arm is controlled according to the target power value, so that the input power of the bridge arm can be adjusted in each switching cycle, thereby controlling the output voltage of the resonant converter, which is conducive to ensuring the stability of the output voltage of the resonant converter in each switching cycle. Therefore, even if the working mode is switched before the current switching cycle, the stability of the output voltage of the resonant converter can be guaranteed.

[0086] S102, determining a target slope control amount corresponding to a counter corresponding to a switching transistor according to a target power value, an input voltage, circuit parameters of a resonant converter and a current operating mode of a full-bridge inverter module; wherein the operating mode includes a full-bridge mode or a half-bridge mode.

[0087] Among them, each switching transistor corresponds to a counter. The counter can count according to the counting step value, for example, the time count is increased by one every time the counting step value, and the counter can output a ramp signal that changes with time. In some other embodiments, the counter can also be replaced by a ramp signal generator. The target slope control amount is the target slope control amount of the comparison threshold, and each counter corresponds to a comparison threshold, that is, each counter corresponds to a target slope control amount. The target slope control amount is related to the target power value. By determining the target slope control amount, the slope control amount corresponding to the counter is the target slope control amount, and the input power of the corresponding bridge arm can reach the target power value, thereby realizing the control of the input power.

[0088] The input voltage is the input voltage of the bridge arm, and the circuit parameters of the resonant converter may be the electrical parameters of the components in the resonant converter.

[0089] Specifically, by determining the target slope control amount corresponding to the counter, the comparison threshold can be obtained according to the product of the count value of the counter and the target slope control amount. Therefore, the comparison threshold is dynamically changed, and it can be determined whether to control the corresponding switch transistor to be turned off according to the comparison threshold, so that the output voltage of the resonant converter can be controlled, which is conducive to ensuring the stability of the output voltage and improving the transient control during the operation of the resonant converter, so as to better control the output of the resonant converter.

[0090] Furthermore, the target slope control amount is determined according to the current working mode of the full-bridge inverter module, and different working modes correspond to different target slope control amounts. When switching the working mode, the target slope control amount corresponding to the current working mode can be determined, so that the target slope control amount corresponding to the updated working mode can be determined when the working mode is switched, so that the comparison threshold determined according to the target slope control amount corresponds to the updated working mode, and the transient control of the resonant converter working mode switching process is realized. Among them, for example, the target slope control amount corresponding to the half-bridge working mode is twice the target slope control amount corresponding to the full-bridge working mode, and it can also be other relationships, which are not limited in this embodiment.

[0091] S103, determining a comparison threshold value according to a target slope control amount, a current count value of a counter corresponding to the switching transistor, and a DC offset voltage of the resonant capacitor corresponding to the current working mode; wherein the counter starts counting with the DC offset voltage as an initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold value.

[0092] Among them, the full-bridge inverter module can convert DC power into AC power, so the voltage of the resonant capacitor is AC voltage, which is approximately a sine wave shape, and the DC offset voltage is the deviation of the sine wave, that is, the voltage of the harmonic capacitor changes around the DC offset voltage, and the counter also starts counting with the DC offset voltage as the initial value.

[0093] When the comparison threshold calculated by the count value of the counter corresponding to the switching transistor of one bridge arm is equal to the actual voltage of the resonant capacitor, the counter stops counting, and the counter corresponding to the other switching transistor of the bridge arm starts counting with the DC offset voltage as the initial value until the comparison threshold calculated by the count value of the counter corresponding to the other switching transistor is equal to the actual voltage of the resonant capacitor.

[0094] Specifically, the target slope control amount can be used as the slope, the count value of the counter can be used as the change value, and the DC offset voltage of the resonant capacitor can be used as the intercept. Then, the curve corresponding to the comparison threshold calculated according to the target slope control amount, the current count value of the counter corresponding to the switching transistor, and the DC offset voltage of the resonant capacitor corresponding to the current operating mode is a straight line, and the straight line changes simultaneously with the AC voltage of the resonant capacitor.

[0095] Furthermore, the DC offset voltage of the resonant capacitor corresponding to different working modes is different. By determining the DC offset voltage of the resonant capacitor according to the current working mode, the calculated comparison threshold can be applicable to different working modes, so that the switching transistor can be controlled even if the working mode is switched.

[0096] S104, determining a control signal according to the actual voltage of the resonant capacitor and a comparison threshold, and controlling the switch transistor according to the control signal.

[0097] Specifically, the control signal is determined according to the actual voltage of the resonant capacitor and the comparison threshold, and the corresponding switch transistor can be controlled. For example, when the comparison threshold calculated by the count value of the counter corresponding to a switch transistor is greater than the actual voltage, the control signal is at an effective level, and the switch transistor is controlled to be turned on; when the comparison threshold is equal to the actual voltage, the control signal is at an invalid level, and the switch transistor is controlled to be turned off until the switch transistor complementary to the switch transistor is turned off, and the switch transistor is turned on again. Among them, for example, the effective level is a high level, and the invalid level is a low level; or the effective level is a low level, and the invalid level is a high level. Among them, the control signals corresponding to the two complementary switch transistors are inverted, that is, when one switch transistor is turned on, the other switch transistor is turned off.

[0098] For example, Figure 1 The resonant converter shown, for example, the first switching transistor Q H1 When turned on, the second switching transistor Q L1 Turn off, the first switching transistor Q H1 When turned off, the second switching transistor Q L1 The first switching transistor Q H1 When turned on, the first switching transistor Q H1 The corresponding counter starts counting, and the first switch transistor Q H1 The comparison threshold calculated by the count value of the corresponding counter is greater than the actual voltage, and the first switch transistor Q H1 Keeping on, the first switching transistor Q H1 When the comparison threshold obtained by the corresponding counter count value is equal to the actual voltage of the resonant capacitor, the first switch transistor Q is controlled H1 Turn off, the second switching transistor Q L1 The second switching transistor QL1 The corresponding counter starts timing, and the second switch transistor Q L1 The comparison threshold calculated by the corresponding counter count value is less than the actual voltage, and the second switch transistor Q L1 Keeping on, the second switch transistor Q L1 When the comparison threshold obtained by the corresponding counter count value is equal to the actual voltage of the resonant capacitor, the second switch transistor Q is controlled L1 This is repeated to achieve waveform control of the actual voltage, and multiple cycles of actual voltage can be output, making it easier to power the load.

[0099] The technical solution of this embodiment is that in each switching cycle, the target power value is determined according to the input power control amount and compensation amount corresponding to the bridge arm, and the target slope control amount corresponding to the counter corresponding to the switching transistor is determined according to the target power value, input voltage, circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module. The comparison threshold can be adjusted according to the target slope control amount, and the on or off of the switching transistor can be controlled according to the relationship between the comparison threshold and the actual voltage of the resonant capacitor, thereby adjusting the input power and realizing direct control of the single-cycle input power. In addition, the DC offset voltage of the resonant capacitor corresponding to different working modes is different, so that the determined comparison threshold can be applied to different working modes, thereby realizing switching of different working modes, and even if the working mode is switched, the output voltage of the resonant converter can be better controlled to achieve stable output of the output voltage. In addition, the comparison threshold is determined according to the count value of the counter, so that the comparison threshold is a variable value, which can improve the transient control during the working process of the resonant converter and realize better control of the output of the resonant converter.

[0100] On the basis of the above technical solution, optionally, the DC offset voltage is the product of the DC offset voltage control amount corresponding to the resonant capacitor in the corresponding working mode and the sampling coefficient.

[0101] For example, the DC offset voltage is V CrBias , the corresponding DC offset voltage control value on the resonant capacitor is V thBias , the sampling coefficient is K sen Then V CrBias =V thBias ×K sen .

[0102] For example, the full-bridge inverter module includes a first bridge arm and a second bridge arm, the first bridge arm includes a first switch transistor and a second switch transistor, and the second bridge arm includes a third switch transistor and a fourth switch transistor, that is, Figure 1The full-bridge inverter module shown. Optionally, the DC offset voltage is the product of the switching duty cycle of the first switch transistor and the first input voltage of the first bridge arm, plus the second input voltage of the second bridge arm, minus the product of the switching duty cycle of the third switch transistor and the second input voltage.

[0103] For example, the switch duty cycle of the first bridge arm is D1, and the first input voltage of the first bridge arm is V in1 , the switch duty cycle of the second bridge arm is D2, and the second input voltage of the second bridge arm is V in2 , when the full-bridge inverter module works in full-bridge mode, the switching duty cycle of the first switching transistor is the switching duty cycle of the first bridge arm, and the switching duty cycle of the third transistor is the switching duty cycle of the second bridge arm. Then V CrBias =D1V in1 +V in2 -D2V in2 , when D1=D2=50%,

[0104] When the full-bridge inverter module works in the half-bridge mode, the switching duty ratios of the first bridge arm and the second bridge arm are both 50%. In steady-state operation, the first bridge arm and the second bridge arm will work at a 50% duty ratio for one cycle, and the actual duty ratio of the first switch transistor is The actual duty cycle of the third switching transistor is but

[0105] On the basis of the above technical solution, optionally, when the working mode of the full-bridge inverter module is switched, the resonant converter control method further includes:

[0106] The half-bridge operating mode of the full-bridge inverter module is enabled or disabled, and the DC offset voltage of the resonant capacitor is updated according to the switched operating mode, and the target slope control amount is updated according to the switched operating mode.

[0107] Specifically, for example, if the default working mode of the full-bridge inverter module is the full-bridge working mode, then when the working mode is switched for the first time, the half-bridge working mode of the full-bridge inverter module needs to be enabled, for example, switched to the low-voltage staggered half-bridge mode. When the working mode is switched again, the half-bridge working mode of the full-bridge inverter module needs to be disabled, and then switched to the full-bridge working mode. And according to the switched working mode, the DC offset voltage and the target slope control amount of the resonant capacitor are updated, so that the comparison threshold determined according to the DC offset voltage and the target slope control amount can be the comparison threshold in the corresponding mode, so that the determined comparison threshold can be applicable to different working modes, so that after the working mode is switched, the resonant converter can still stabilize the output voltage.

[0108] Enable or disable the half-bridge working mode of the full-bridge inverter module, and update the DC offset voltage of the resonant capacitor according to the switched working mode, and update the target slope control amount according to the switched working mode. This can be executed before the working mode is switched, that is, before the first switching cycle after the working mode is switched, so as to facilitate a smooth transition when the working mode is switched.

[0109] Based on the above technical solutions, Figure 7 is a flowchart of another resonant converter control method provided by an embodiment of the present invention. Optionally, refer to Figure 7 , the resonant converter control method includes:

[0110] S201 . In each switching cycle, input the output voltage of the resonant converter, a reference voltage, and a first feedback coefficient into an output voltage closed-loop controller to obtain a first deviation value.

[0111] Specifically, the output voltage can be divided by the first feedback coefficient to obtain the first feedback voltage, and then the difference between the reference voltage and the first feedback voltage is input into the voltage closed-loop controller, so that the voltage closed-loop controller outputs a first deviation value, so as to control the output voltage of the resonant converter according to the first deviation value. The voltage closed-loop controller can be a proportional integral (PI) controller, a proportional integral differential (PID) controller or other types of controllers, which are not limited in this embodiment.

[0112] For example, the reference voltage is V ref , the output voltage is V out , the first feedback coefficient is K VO , then the first feedback voltage is The difference between the reference voltage and the first feedback voltage is

[0113] S202, obtaining a power feedforward value according to the output voltage, the output current of the resonant converter, the first feedback coefficient and the second feedback coefficient, and obtaining an initial target input power value according to the power feedforward value and the first deviation value.

[0114] Specifically, the output voltage can be divided by the first feedback coefficient to obtain the first feedback voltage. The output current can be divided by the second feedback coefficient to obtain the first feedback current, and the first feedback voltage and the first feedback current can be multiplied to obtain the power feedforward value. The power feedforward value and the first deviation value can be added to obtain the initial target input power value. In this way, the target input power value can be determined according to the output parameters and input parameters of the resonant converter, so as to facilitate the adjustment of the input power according to the output parameters and input parameters of the resonant converter, thereby realizing direct control of the input power.

[0115] Exemplarily, the output current of the resonant converter is I out , the second feedback coefficient is, for example, K io , then the first feedback current is The first feedback voltage is Then the power feedforward value P outN for For example, the first deviation value is ΔP inN , then the initial target input power value P inN P inN =P outN +ΔP inN .

[0116] S203, input the first input voltage, the second input voltage and the sampling coefficient into the input voltage equalizing closed-loop controller to obtain a second deviation value; wherein the full-bridge inverter module includes a first bridge arm and a second bridge arm, the first input voltage is the input voltage of the first bridge arm, and the second input voltage is the input voltage of the second bridge arm.

[0117] Specifically, the first input voltage is divided by the sampling coefficient to obtain the first actual input voltage, and the second input voltage is divided by the sampling coefficient to obtain the second actual input voltage. The difference between the first actual input voltage and the second actual input voltage is input into the input voltage equalizing closed-loop controller, and the input voltage equalizing closed-loop controller will output a second deviation value. In this way, the difference between the input voltages of the two bridge arms in the full-bridge inverter module can be determined, so that the input power can be adjusted according to the difference between the input voltages of the two bridge arms, thereby balancing the input voltages of the two bridge arms. In this way, the problem of uneven voltage in the two bridge arms that occurs easily during long-term operation can be avoided. Among them, the input voltage equalizing closed-loop controller can be a proportional-integral controller, or a proportional-integral-differential controller or other types of controllers, which are not limited in this embodiment.

[0118] Exemplarily, the first input voltage is V in1 , the second input voltage is V in2 , the sampling coefficient is K sen , then the first actual input voltage is The second actual input voltage is The difference between the first actual input voltage and the second actual input voltage is Input to the input voltage controller, the input voltage controller will output the second deviation value ΔP in12N .

[0119] S204: Determine an input power control amount according to the initial target input power value, the second deviation value, and the normalization coefficient.

[0120] Specifically, for example, the full-bridge inverter module includes a first bridge arm and a second bridge arm. The initial target input power value is multiplied by a normalization coefficient to obtain a first normalized value, the second deviation value is multiplied by a normalization coefficient to obtain a second normalized value, and the first normalized value is added to the second normalized value to obtain an input power control amount corresponding to the first bridge arm. The second normalized value is subtracted from the first normalized value to obtain an input power control amount corresponding to the second bridge arm, that is, to obtain an input power control amount corresponding to each bridge arm. The normalization coefficient may be a preset value.

[0121] For example, the normalization coefficient is Initial target input power value P inN Multiply by the normalization coefficient to get the first normalized value The second deviation value ΔP in12N Multiply by the normalization coefficient to get the second normalized value The first normalized value With the second normalized value Add together to get the input power control quantity K corresponding to the first bridge arm pin1 , the first normalized value Subtract the second normalized value Get the input power control value K corresponding to the second bridge arm pin2 In this way, it is convenient to determine the target power value according to the input power control amount, thereby realizing direct control of the input power of the bridge arm.

[0122] S205 . In each switching cycle, determine a target power value according to an input power control amount and a compensation amount corresponding to the bridge arm.

[0123] S206. Determine a target slope control amount corresponding to a counter corresponding to a switching transistor according to a target power value, an input voltage, circuit parameters of a resonant converter and a current operating mode of a full-bridge inverter module; wherein the operating mode includes a full-bridge mode or a half-bridge mode.

[0124] S207, determining a comparison threshold value according to the target slope control amount, the current count value of the counter corresponding to the switching transistor, and the DC offset voltage of the resonant capacitor corresponding to the current working mode; wherein the counter starts counting with the DC offset voltage as the initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold value.

[0125] S208 , determining a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switch transistor according to the control signal.

[0126] On the basis of the above technical solutions, Figure 8 is a flowchart of another resonant converter control method provided by an embodiment of the present invention. Optionally, refer to Figure 8 , the resonant converter control method includes:

[0127] S301 . In each switching cycle, a target power value is determined according to an input power control amount and a compensation amount corresponding to a bridge arm.

[0128] S302, determining the change slope control amount corresponding to each bridge arm according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor, and determining the full-bridge slope control amount and the half-bridge slope control amount according to the change slope control amount.

[0129] Specifically, for example, the full-bridge inverter module includes a first bridge arm and a second bridge arm. The input power of the first bridge arm is P inB1 , the input power of the second bridge arm is P inB2 , the capacitance of the resonant capacitor is C r , the bridge arm switching frequency is f s , the input voltage of the first bridge arm is V in1 , the input voltage of the second bridge arm is V in2 , then the input power of the first bridge arm (the target power value of the first bridge arm) is The input power of the second bridge arm (the target power value of the second bridge arm) is Among them, v Cr (t H1off ) is the first switch transistor Q H1 The voltage of the resonant capacitor at the time of opening or closing, v Cr (t L1off ) is the second switch transistor Q L1 The voltage of the resonant capacitor at the time of opening or closing, v Cr (t L2off ) is the fourth switch transistor Q L2 The voltage of the resonant capacitor at the time of opening or closing, v Cr (t H2off ) is the third switch transistor Q H2 The voltage of the resonant capacitor at the time of turning on or off. C j is the output capacitance of the switching transistor.

[0130] Moreover, the product of the counter's counting step value and the count value can represent the duty cycle of the control signal of the switching transistor, so the bridge arm switching frequency is f sIt can be represented by the counting step value and the counting value of the counter. The ratio of the voltage difference of the resonant capacitor corresponding to the two complementary conductive switching transistors turned off to the sampling coefficient can be represented by the changing slope control amount and the counting value. Therefore, the input power can be obtained by using the changing slope control amount, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor. The changing slope control amount can be determined according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor.

[0131] Among them, the change slope control amount is the full-bridge slope control amount. Multiplying the change slope control amount by 2 can get the half-bridge slope control amount. Because when working in the half-bridge mode, the conduction of the primary switching transistor is interleaved and prohibited, the change slope control amount corresponding to the half-bridge mode must be twice the change slope control amount corresponding to the full-bridge mode to make the input power of the half-bridge mode and the full-bridge mode consistent.

[0132] S303: Determine a full-bridge slope control amount or a half-bridge slope control amount as a target slope control amount according to a current working mode of the full-bridge inverter module.

[0133] Specifically, if the current working mode of the full-bridge inverter module is the full-bridge working mode, the target slope control amount is the full-bridge slope control amount. If the current working mode of the full-bridge inverter module is the half-bridge working mode, the target slope control amount is the half-bridge slope control amount. In this way, the target slope control amount is applicable to different working modes.

[0134] S304, determining a comparison threshold value according to the target slope control amount, the current count value of the counter corresponding to the switching transistor, and the DC offset voltage of the resonant capacitor corresponding to the current working mode; wherein the counter starts counting with the DC offset voltage as the initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold value.

[0135] S305 , determining a control signal according to the actual voltage of the resonant capacitor and a comparison threshold, and controlling the switch transistor according to the control signal.

[0136] On the basis of the above technical solution, optionally, the change slope control amount corresponding to each bridge arm is determined according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor, including:

[0137] Step a1: Divide the target power value by the input voltage of the corresponding bridge arm and by the capacitance of the resonant capacitor to obtain a first intermediate value.

[0138] Step a2: divide the first intermediate value by the sampling coefficient and multiply it by the counting step value to obtain the change slope control amount of the corresponding bridge arm.

[0139] Specifically, for example, the full-bridge inverter module includes a first bridge arm and a second bridge arm. The input power of the first bridge arm is P inB1 , the input power of the second bridge arm is P inB2 , the capacitance of the resonant capacitor is C r , the bridge arm switching frequency is f, and the input voltage of the first bridge arm is V in1 , the input voltage of the second bridge arm is V in2 , then the input power of the first bridge arm is The input power of the second bridge arm is Among them, v Cr (t H1off ) is the first switch transistor Q H1 The voltage of the resonant capacitor at the time of opening or closing, v Cr (t L1off ) is the second switch transistor Q L1 The voltage of the resonant capacitor at the time of opening or closing, v Cr (t L2off ) is the fourth switch transistor Q L2 The voltage of the resonant capacitor at the time of opening or closing, v cr (t H2off ) is the third switch transistor Q H2 The voltage of the resonant capacitor at the time of turning on or off. C j is the output capacitance of the switching transistor. j Much smaller than the capacitance C of the resonant capacitor r , and The proportion of is small, usually much smaller than the minimum load power, and can be ignored. Then P inBx =V inx C r f s [v Cr (t Hxoff )-v Cr (t Lxoff )], where P inBx is the input power P of the first bridge arm inB1 Or the input power P of the second bridge arm inB2 , v Cr (t Hxoff ) is v cr (t H1off ) or v cr (t H2off ), v cr (t Lxoff ) is v Cr (tL1off ) or v Cr (t L2off ), V inx V in1 or V in2 .

[0140] When the bridge arms switch symmetrically, the duration of each switching transistor turning on or off is half of the switching period, so Among them, K T is the counting step value of the counter, Count off is the count value of the counter. Then Right now Among them, K sen is the sampling coefficient, K th is the change slope control amount.

[0141] Therefore, Substitute into P inBx =V inx C r f s [v Cr (t Hxoff )-v Cr (t Lxoff )], we can get Right now Therefore, the target power value is divided by the input voltage of the corresponding bridge arm and divided by the capacitance of the resonant capacitor to obtain the first intermediate value Divide the first intermediate value by the sampling coefficient and multiply it by the counting step value to obtain the change slope control amount of the corresponding bridge arm, that is,

[0142] On the basis of the above technical solutions, optionally, a control signal is determined according to the actual voltage of the resonant capacitor and the comparison threshold, and the switch transistor of the bridge arm is controlled according to the control signal, including:

[0143] Step b1: when the ratio of the actual voltage to the sampling coefficient is less than the comparison threshold, the first target switch transistor in the corresponding bridge arm is controlled to be turned on.

[0144] The first target switch transistor may be the first switch transistor Q H1 or the third switching transistor Q H2 , can also be the second switching transistor Q L1 or the fourth switching transistor Q L2 .

[0145] Specifically, by setting the sampling coefficient, it is convenient to restore the actual voltage obtained by sampling. The ratio of the actual voltage to the sampling coefficient is the real voltage of the resonant capacitor. When the ratio of the actual voltage to the sampling coefficient is less than the comparison threshold, the first target switch transistor in the corresponding bridge arm can be controlled to be turned on. When the ratio of the actual voltage to the sampling coefficient is equal to the comparison threshold, the first target switch transistor in the corresponding bridge arm is controlled to be turned off, and the counter corresponding to the first target switch transistor can stop counting until the second target switch transistor complementary to the first target switch transistor is turned off, the first target switch transistor is turned on, and the counter corresponding to the first target switch transistor starts counting again. Thereby controlling the voltage change on the resonant capacitor, and then controlling the output voltage of the resonant converter, so that the resonant converter stabilizes the output voltage.

[0146] Step b2: when the absolute value of the ratio of the actual voltage to the sampling coefficient is greater than the comparison threshold, the second target switch transistor in the corresponding bridge arm is controlled to be turned on.

[0147] For example, the first target switch transistor is the first switch transistor Q H1 , then the second target switch transistor is the second switch transistor Q L1 ; or the first target switching transistor is the third switching transistor Q H2 , then the second target switch transistor is the fourth switch transistor Q L2 .

[0148] Specifically, when the ratio of the actual voltage to the sampling coefficient is less than the comparison threshold, the second target switch transistor is turned off and the first target switch transistor is turned on. When the ratio of the actual voltage to the sampling coefficient is greater than the comparison threshold and the first target switch transistor is turned off, the second target switch transistor in the bridge arm is controlled to be turned on, and the counter corresponding to the second target switch transistor starts counting until the absolute value of the ratio of the actual voltage to the sampling coefficient is equal to the comparison threshold calculated by the count value of the counter corresponding to the second target switch transistor, and the second target switch transistor is controlled to be turned off and the first target switch transistor is turned on. In this way, the complementary switching of the first target switch transistor and the second target switch transistor is realized, so that the voltage on the resonant capacitor is an AC voltage. Thereby controlling the voltage change on the resonant capacitor, and then controlling the output voltage of the resonant converter, so that the resonant converter can stabilize the output voltage.

[0149] Optionally, a control signal is determined according to the actual voltage of the resonant capacitor and the comparison threshold, and a switch transistor of the bridge arm is controlled according to the control signal, further comprising:

[0150] When the ratio of the actual voltage to the sampling coefficient is equal to the comparison threshold corresponding to the first target switch transistor, the first target switch transistor corresponding to the counter is controlled to be turned off, and the second target switch transistor is controlled to be turned on, wherein the control signal of the first target switch transistor is inverse to the control signal corresponding to the second target switch transistor. That is, when the control signal of the first target switch transistor is at a high level, the control signal of the second target switch transistor is at a low level; when the control signal of the first target switch transistor is at a low level, the control signal of the second target switch transistor is at a high level, so that when the first target switch transistor is turned on, the second target switch transistor is turned off; when the first target switch transistor is turned off, the second target switch transistor is turned on, that is, the first target switch transistor and the second target switch transistor are turned on complementary to each other.

[0151] Specifically, when the ratio of the actual voltage to the sampling coefficient is equal to the comparison threshold corresponding to the first target switching transistor, the first target switching transistor corresponding to the control counter is turned off, and the second target switching transistor is controlled to be turned on, so as to realize the complementary conduction of the first target switching transistor and the second switching transistor, so that the voltage on the resonant capacitor is an alternating voltage, thereby realizing the control of the voltage on the resonant voltage, and then controlling the output voltage of the resonant converter, so that the resonant converter can stabilize the output voltage.

[0152] On the basis of the above technical solutions, optionally, the target power value is determined according to the input power control amount and compensation amount corresponding to the bridge arm, including:

[0153] The sum of the input power control amount and the compensation amount corresponding to the bridge arm is taken as the target power value corresponding to the bridge arm.

[0154] Specifically, by setting the compensation amount, the input power control amount can be compensated, so as to improve the accuracy of determining the target power value. The compensation amount can be a preset value.

[0155] For example, the input power control quantity corresponding to the first bridge arm is K pin1 , the compensation amount of the first bridge arm is K c1 , the target power value of the first bridge arm is P inB1 , then P inB1 =K pin1 +K c1 For example, the input power control amount corresponding to the second bridge arm is K pin2 , the compensation amount of the second bridge arm is K c2 , the target power value of the second bridge arm is P inB2 , then P inB2 =K pin2 +K c2 .

[0156] For example, Fig. 9is a schematic diagram of a time domain operating waveform of a resonant converter provided by an embodiment of the present invention, such as Fig. 9 As shown, the first current waveform I s1 The first rectifier transistor S H1 The current of the second current waveform I s2 The second rectifier transistor S H2 The third current waveform I Lr is the current flowing through the resonant inductor L r The fourth current waveform I Lm is the current flowing through the magnetizing inductance L m The current; V Cr is the actual voltage of the resonant capacitor. V Tin1 ,V Tin2 are the output voltages of the first bridge arm and the second bridge arm respectively; G H1 ,G L1 ,G H2 ,G L2 The first switching transistor Q H1 , the second switching transistor Q L1 , the third switch transistor Q H2 , the fourth switch transistor Q L2 The gate voltage of thBiasFB1 is the DC offset voltage corresponding to the resonant capacitor of the first bridge arm in full-bridge mode; V thBiasFB2 is the DC offset voltage corresponding to the resonant capacitor of the second bridge arm in full-bridge mode; V thBiasHB1 is the DC offset voltage on the resonant capacitor of the first bridge arm in half-bridge mode; V thBiasHB2 is the DC offset voltage on the resonant capacitor of the second bridge arm in half-bridge mode; K sen is the sampling coefficient; V thH1FB It is the first switching transistor Q in full bridge mode. H1 The corresponding comparison threshold; V thH2_FB The third switching transistor Q in full-bridge mode H2 The corresponding comparison threshold when shutting down; V thL1_FB The second switching transistor Q in full-bridge mode L1 The corresponding comparison threshold when shutting down; V thL2_FB It is the fourth switch transistor Q in full bridge mode. L2 The corresponding comparison threshold when shutting down; V thH1_HB It is the first switching transistor Q in half-bridge mode. H1 The corresponding comparison threshold when shutting down; V thH2_HB The third switching transistor Q in half-bridge mode H2 The corresponding comparison threshold when shutting down; V thL1_HB The second switching transistor Q in half-bridge mode L1 The corresponding comparison threshold when shutting down; VthL2_HB The fourth switching transistor Q in half-bridge mode L2 The corresponding comparison threshold when shutting down; V in1 is the input voltage of the first bridge arm; V in2 is the input voltage of the second bridge arm; t0 to t6 and t0' to t6' are the key control time points in the topology working mode switching process; T FB is the switching period of the full-bridge mode; T HB is the switching period of half-bridge mode.

[0157] Wherein, straight line ① is the change slope control amount (target slope control amount) K of the comparison threshold value corresponding to the first switch transistor in the full-bridge mode th1_FB The comparison threshold is obtained by multiplying the product of the count value and the DC offset voltage of the resonant capacitor in the full-bridge mode, that is, the comparison threshold corresponding to the first switch transistor in the full-bridge mode changes along the straight line ①. Straight line ② is the change slope control amount (target slope control amount) K of the comparison threshold corresponding to the second switch transistor in the full-bridge mode. th2_FB The comparison threshold is obtained by multiplying the product of the count value and the DC offset voltage of the resonant capacitor in the full-bridge mode, that is, the comparison threshold corresponding to the second switch transistor in the full-bridge mode changes along straight line ②. Straight line ③ is the change slope control amount (target slope control amount) K of the comparison threshold of the third switch transistor corresponding to the full-bridge mode. th3_FB The comparison threshold obtained by adding the product of the count value and the DC offset voltage of the resonant capacitor in the full-bridge mode, that is, the comparison threshold corresponding to the third switch transistor in the full-bridge mode changes along straight line ③. Straight line ④ is the change slope control amount (target slope control amount) K of the comparison threshold corresponding to the fourth switch transistor in the full-bridge mode. th4_FB The comparison threshold obtained by adding the product of the count value and the DC offset voltage of the resonant capacitor in the full-bridge mode, that is, the comparison threshold corresponding to the fourth switch transistor in the full-bridge mode, changes along the straight line ④.

[0158] Straight line ⑤ is the change slope control amount (target slope control amount) K of the comparison threshold corresponding to the first switch transistor in the half-bridge mode th1_HB The comparison threshold obtained by adding the product of the count value and the DC offset voltage of the resonant capacitor in the half-bridge mode, that is, the comparison threshold corresponding to the first switch transistor in the half-bridge mode changes along the straight line ⑤. Straight line ⑥ is the change slope control amount (target slope control amount) K of the comparison threshold corresponding to the second switch transistor in the half-bridge mode. th2_HB The comparison threshold is obtained by multiplying the product of the count value and the DC offset voltage of the resonant capacitor in the half-bridge mode, that is, the comparison threshold corresponding to the second switch transistor in the half-bridge mode changes along the straight line ⑥. Straight line ⑦ is the change slope control amount (target slope control amount) K of the comparison threshold corresponding to the third switch transistor in the half-bridge mode. th3_HBThe comparison threshold obtained by adding the product of the count value and the DC offset voltage of the resonant capacitor in the half-bridge mode, that is, the comparison threshold corresponding to the third switch transistor in the half-bridge mode changes along the straight line ⑦. Straight line ⑧ is the change slope control amount (target slope control amount) K of the comparison threshold corresponding to the fourth switch transistor in the half-bridge mode. th4_HB The comparison threshold obtained by multiplying the product of the count value and the DC offset voltage of the resonant capacitor in the half-bridge mode, that is, the comparison threshold corresponding to the fourth switch transistor in the half-bridge mode, changes along the straight line ⑧.

[0159] like Fig. 9 As shown, when the first switch transistor is turned on, straight line ① is above the actual voltage of the resonant capacitor, that is, the ratio of the actual voltage of the resonant capacitor to the sampling coefficient is less than the comparison threshold, and the actual voltage of the resonant capacitor gradually increases. When the ratio of the actual voltage of the resonant capacitor to the sampling coefficient is equal to the comparison threshold on straight line ①, the first switch transistor is turned off, the second switch transistor is turned on, the actual voltage of the resonant capacitor gradually decreases, the counter corresponding to the second switch transistor starts counting, and the comparison threshold changes along straight line ② until the ratio of the actual voltage of the resonant capacitor to the sampling coefficient is equal to the comparison threshold on straight line ②, and the second switch transistor is turned off to achieve control of a switching cycle.

[0160] like Fig. 9 As shown, at time t2, when the working mode of the resonant converter is switched from the full-bridge mode to the half-bridge mode, the DC offset voltage and the target slope control amount of the resonant capacitor change. When the first switch transistor is turned on, the straight line ⑤ is above the actual voltage of the resonant capacitor, that is, the ratio of the actual voltage of the resonant capacitor to the sampling coefficient is less than the comparison threshold, and the actual voltage of the resonant capacitor gradually increases. When the ratio of the actual voltage of the resonant capacitor to the sampling coefficient is equal to the comparison threshold on the straight line ⑤, the first switch transistor is turned off, the second switch transistor is turned on, the actual voltage of the resonant capacitor gradually decreases, the counter corresponding to the second switch transistor starts counting, and the comparison threshold changes along the straight line ⑥ until the ratio of the actual voltage of the resonant capacitor to the sampling coefficient is equal to the comparison threshold on the straight line ⑥, and the second switch transistor is turned off to achieve control of a switching cycle. In this way, stable control of the output voltage is achieved, and a smooth transition can be achieved when the mode is switched.

[0161] The control principle of the third switch transistor and the fourth switch transistor is the same as that of the first switch transistor and the second switch transistor, which will not be described in detail here.

[0162] Fig.10 is a schematic diagram of a state plane operation trajectory of a resonant converter switching from a full-bridge mode to a half-bridge mode provided by an embodiment of the present invention, such as Fig.10 As shown, the horizontal axis is the actual voltage V of the resonant capacitor Cr , the vertical axis is the current I of the resonant inductor LrAt time t2, the resonant converter switches from full-bridge mode to half-bridge mode, and a smooth transition can be achieved.

[0163] Fig.11 is a schematic diagram of a state plane operation trajectory of a resonant converter switching from a half-bridge mode to a full-bridge mode provided by an embodiment of the present invention, such as Fig.11 As shown, the horizontal axis is the actual voltage V of the resonant capacitor Cr , the vertical axis is the current I of the resonant inductor Lr At time t2', the resonant converter switches from half-bridge mode to full-bridge mode, and a smooth transition can be achieved.

[0164] exist Fig.10 and Fig.11 In, V thLx_FB V thL1_FB or V thL2_FB , V thL1_FB The second switching transistor Q in full-bridge mode L1 The corresponding comparison threshold when shutting down; V thL2_fB It is the fourth switch transistor Q in full bridge mode. L2 The comparison threshold corresponding to shutdown. V thLx_HB V thL1_HB or V thL2_HB , V thL1_HB The second switching transistor Q in half-bridge mode L1 The corresponding comparison threshold when shutting down; V thL2_HB The fourth switching transistor Q in half-bridge mode L2 The comparison threshold corresponding to shutdown. V thHx_HB V thH1_HB or V thH2_HB , V thH1_HB It is the first switching transistor Q in half-bridge mode. H1 The corresponding comparison threshold when shutting down; V thH2_H The third switching transistor Q in half-bridge mode H2 The comparison threshold corresponding to shutdown. V thHx_FB V thH1_F or V thH2_FB , V thH1_FB It is the first switching transistor Q in full bridge mode. H1 The corresponding comparison threshold when shutting down; V thH2_FB The third switching transistor Q in full-bridge mode H2 Comparison threshold corresponding to shutdown.

[0165] The embodiment of the present invention further provides a resonant converter control system. Fig.12 is a schematic diagram of a resonant converter control system provided by an embodiment of the present invention, with reference to Fig.12, the resonant converter control system includes: a target power value determination module 110, a target slope control amount determination module 120, a comparison threshold determination module 130 and a control module 140;

[0166] The target power value determination module 110 is used to determine the target power value according to the input power control amount and compensation amount corresponding to the bridge arm in each switching cycle;

[0167] The target slope control amount determination module 120 is connected to the target power value determination module 110, and the target slope control amount determination module 120 is used to determine the target slope control amount corresponding to the counter corresponding to the switching transistor according to the target power value, the input voltage, the circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module; wherein the working mode includes a full-bridge mode or a half-bridge mode;

[0168] The comparison threshold determination module 130 is connected to the target slope control amount determination module 120, and the comparison threshold determination module 130 is used to determine the comparison threshold according to the target slope control amount, the current count value of the counter corresponding to the switching transistor, and the DC offset voltage of the resonant capacitor corresponding to the current working mode; wherein the counter starts counting with the DC offset voltage as the initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold;

[0169] The control module 140 is connected to the comparison threshold determination module 130 , and is used to determine a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and control the switch transistor according to the control signal.

[0170] The target power value determination module 110, the target slope control amount determination module 120, the comparison threshold determination module 130 and the control module 140 can all be implemented by circuits, and the resonant converter control system can execute the resonant converter control method provided by any embodiment of the present invention. The resonant converter control system has the same beneficial effects as the resonant converter control method provided by any embodiment of the present invention, which will not be repeated here.

[0171] On the basis of the above technical solution, the circuit structures that may be included in the target power value determination module 110, the target slope control amount determination module 120, the comparison threshold determination module 130 and the control module 140 are described below, but this is not intended to limit the present application.

[0172] Based on the above technical solutions, Fig.13 is a schematic diagram of a structure of another resonant converter control system provided by an embodiment of the present invention. Fig.13 , the target power value determination module 110 includes a first adder U1;

[0173] The first input terminal of the first adder U1 is connected to the input power control amount, and the second input terminal of the first adder U1 is connected to the compensation amount; the first adder U1 is used to add the input power control amount and the compensation amount to obtain a target power value.

[0174] Specifically, the first adder U1 is set in one-to-one correspondence with the bridge arm, and the first adder U1 adds the input power control amount and the compensation amount to obtain the target power value. For example, the input power control amount corresponding to the first bridge arm is K pin1 , the compensation amount of the first bridge arm is K c1 , the target power value of the first bridge arm is P inB1 , then P inB1 =K pin1 +K c1 For example, the input power control amount corresponding to the second bridge arm is K pin2 , the compensation amount of the second bridge arm is K c2 , the target power value of the second bridge arm is P inB2 , then P inB2 =K pin2 +K c2 .

[0175] Optionally, refer to Fig.13 The target power value determination module 101 also includes a first multiplier U2, a second adder U3 and a voltage closed-loop controller U4. The first multiplier U2 is used to convert the output voltage V out The inverse of the first feedback coefficient Multiplying by, the first feedback voltage is The second adder U3 is used to convert the reference voltage V ref Subtracting the first feedback voltage is the difference The voltage closed-loop controller U4 is used to control the voltage according to the reference voltage V ref Subtracting the first feedback voltage is the difference Output the first deviation value ΔP inN .

[0176] Optionally, refer to Fig.13 The target power value determination module 110 also includes a second multiplier U5, a third multiplier U6 and a third adder U7. The second multiplier U5 is used to convert the output current I out The inverse of the second feedback coefficient Multiply them to get the first feedback current The third multiplier U6 is used to multiply the first feedback voltage and the first feedback current to obtain a power feedforward value P outN for The third adder U7 is used to add the first deviation value ΔP inN and the power feedforward value P outN Add up to get the initial target input power value PinN , that is, P inN =P outN +ΔP inN .

[0177] Optionally, refer to Fig.13 The target power value determination module 110 also includes a fourth multiplier U8, a fifth multiplier U9, a fourth adder U10 and an input voltage equalizing closed-loop controller U11; the fourth multiplier U8 is used to convert the first input voltage V in1 The inverse of the sampling factor Multiply to get the first actual input voltage The fifth multiplier U9 is used to multiply the second input voltage V in2 The inverse of the sampling factor Multiply by to get the second actual input voltage The fourth adder U10 is used to calculate the difference between the first actual input voltage and the second actual input voltage. The input voltage equalizing closed-loop controller U11 is used to calculate the difference between the first actual input voltage and the second actual input voltage. Output the second deviation value ΔP in12N .

[0178] Optionally, refer to Fig.13 The target power value determination module 110 also includes a sixth multiplier U12, a seventh multiplier U13, a fifth adder U14 and a sixth adder U15; the sixth multiplier U12 is used to convert the initial target input power value P inN Multiply by the normalization coefficient to get the first normalized value The seventh multiplier U13 is used to multiply the second deviation value ΔP in12N Multiply by the normalization coefficient to get the second normalized value The fifth adder U14 is used to convert the first normalized value With the second normalized value Add together to get the input power control quantity K corresponding to the first bridge arm pin1 ; The sixth adder U15 is used to add the first normalized value Subtract the second normalized value Get the input power control value K corresponding to the second bridge arm pin2 In this way, it is convenient to determine the target power value according to the input power control amount, thereby realizing direct control of the input power of the bridge arm.

[0179] Optionally, refer to Fig.13The target slope control amount determination module 120 includes a first divider U16 and an eighth multiplier U17. The first divider U16 is used to divide the target power value by the ratio of the input voltage to the sampling coefficient. The eighth multiplier U17 is used to multiply the output value of the first divider U16 by the ratio of the counting step value of the counter to the square of the sampling coefficient and the capacitance of the resonant capacitor. In this way, the The target slope control value K is obtained by calculation th .

[0180] Optionally, refer to Fig.13 The resonant converter control system further includes a mode switching unit U18, which is used to output a mode value Mode according to a switching control signal. For example, an output mode value Mode of 1 indicates a full-bridge mode, and an output mode value Mode of 0 indicates a half-bridge mode; or an output mode value Mode of 0 indicates a full-bridge mode, and an output mode value Mode of 1 indicates a half-bridge mode.

[0181] It should be noted that Fig.13 In the embodiment, the mode switching unit U18 is located in the target power value determining module 110 , but this does not mean that the mode switching unit U18 belongs to the target power value determining module 110 .

[0182] Optionally, refer to Fig.13 The comparison threshold determination module 130 includes a first selector U19, a second selector U20, a ninth multiplier U21, a seventh adder U22 and a counter U23; the first selector U19 is used to select the full-bridge slope control amount or the half-bridge slope control amount as the target slope control amount according to the mode value. The second selector U20 is used to select the DC offset voltage corresponding to the half-bridge mode or the DC offset voltage corresponding to the full-bridge mode according to the mode value. The ninth multiplier U21 is used to multiply the target slope control amount with the count value output by the counter U23, and the seventh adder U22 is used to add the result of multiplying the target slope control amount with the count value output by the counter U23 to the DC offset voltage, thereby obtaining the comparison threshold.

[0183] like Fig.13 As shown, V thBiasFB1 is the DC offset voltage corresponding to the resonant capacitor of the first bridge arm in full-bridge mode; V thBiasFB2 is the DC offset voltage corresponding to the resonant capacitor of the second bridge arm in full-bridge mode; V thBiasHB1 is the DC offset voltage on the resonant capacitor of the first bridge arm in half-bridge mode; V thBiasHB2 is the DC offset voltage on the resonant capacitor of the second bridge arm in half-bridge mode; K th1_F is the change slope control value of the comparison threshold in the first bridge arm full-bridge mode; K th2_FB K is the change slope control value of the comparison threshold in the full-bridge mode of the second bridge arm;th1_HB is the change slope control value of the comparison threshold in the first bridge arm half-bridge mode; K th2_HB is the change slope control value of the comparison threshold in the second bridge arm half-bridge mode; V thBiasB1 is the DC offset voltage of the first bridge arm output by the second selector corresponding to the first bridge arm, V thBiasB2 It is the DC offset voltage of the second bridge arm output by the second selector corresponding to the second bridge arm.

[0184] Optionally, refer to Fig.13 The control module 140 includes a trigger U24 and a comparator U25. The comparator U25 is used to control the corresponding switch transistor to turn off when the comparison threshold corresponding to the count value output by the counter U23 is equal to the ratio of the actual voltage of the resonant capacitor to the sampling coefficient; the trigger U24 is used to trigger the reset of the counter U23 when the comparator U25 outputs a signal to control the switch transistor to turn off, so that the counter U23 can restart counting next time. In this way, the control of the switch transistor is achieved, thereby controlling the output voltage of the resonant converter. Among them, the trigger U24 is, for example, an RS trigger. In some other embodiments, the trigger U24 can also be a D trigger or other triggers, which is not limited in this embodiment.

[0185] Based on the above technical solutions, the resonant converter includes a full-bridge inverter module 11, a resonant module 12 and a rectifier module 13. The full-bridge inverter module can be Figure 1 The series full-bridge circuit shown can also be other circuits. Fig.14 is a circuit structure diagram of a full-bridge inverter module provided by an embodiment of the present invention, such as Fig.14 As shown, the full-bridge inverter module 11 is a parallel full-bridge circuit. The resonance module 12 may include Figure 1 The resonant circuit and transformer shown may also include other circuits, Fig.15 is a schematic diagram of a circuit structure of a resonance module provided by an embodiment of the present invention, such as Fig.15 As shown, the resonance module 12 includes a first resonance capacitor C r1 , the second resonant capacitor C r2 , the first resonant inductor L r1 , the second resonant inductor L r and the magnetizing inductance L m . Fig.16 is a schematic diagram of the circuit structure of another resonant module provided by an embodiment of the present invention. The resonant converter control method and resonant converter control system of the present invention can be applied to Figure 1 , Fig.15 or Fig.16 In the resonant converter formed by any resonant module shown in FIG. Figure 1The parallel full-bridge rectifier circuit shown can also be other circuits, such as Fig.17 is a schematic diagram of a circuit structure of a rectifier module provided in an embodiment of the present invention, such as Fig.17 As shown, the rectifier module 13 includes components and Figure 1 The components of the rectifier module are the same. Fig.17 The rectifier module 13 shown includes a series full-bridge rectifier circuit. Fig.18 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention, such as Fig.18 As shown, the rectifier module 13 includes a half-bridge rectifier circuit. Figure 1 and Fig.17 The difference of the rectifier module 13 is that Fig.18 The second output capacitor C out2 Including high voltage output capacitor C out2 and low voltage output capacitor C out2L . Fig.19 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention, such as Fig.19 As shown, the rectifier module 13 includes a center-tapped transformer rectifier circuit. Fig. 20 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention, such as Fig. 20 As shown, the rectifier module 13 includes a half-bridge high-frequency chain rectifier circuit, and the rectifier module 13 includes a first high-frequency rectifier transistor S H1a , the second high frequency rectifier transistor S H1b , the third high frequency rectifier transistor S L1a , the fourth high frequency rectifier transistor S L1b , the first output capacitor C out1 , the second output capacitor C out2 and output capacitor C out . Fig.21 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention, such as Fig.21 As shown, the rectifier module 13 includes a full-bridge high-frequency chain rectifier circuit. Fig. 22 is a circuit structure diagram of another rectifier module provided in an embodiment of the present invention, such as Fig. 22 As shown, the rectifier module 13 includes a cascade rectifier circuit. The resonant converter control method and resonant converter control system of the present invention can be applied to Figure 1 , Figure 17-Figure 22 In the resonant converter formed by any rectifier module 13 shown.

[0186] The resonant converter control method and the resonant converter control system according to the embodiments of the present invention are used to Figure 1 The resonant converter shown in FIG. 1 is used for control. The circuit parameter values ​​of the resonant converter are shown in Table 1.

[0187] Table 1 Circuit parameter values ​​of resonant converter

[0188] parameter value <![CDATA[Resonant inductor (L r )]]> 62μH <![CDATA[Excitation inductance (L m )]]> 190μH Transformer turns ratio (n) 28:1 <![CDATA[Resonant capacitor (C r )]]> 40nF <![CDATA[Input filter capacitor (C in1 , C in2 )]]> 2μF <![CDATA[Output filter capacitor (C out )]]> 1000μF <![CDATA[Input voltage (V in )]]> 700V <![CDATA[Output voltage (V out )]]> 13V <![CDATA[Load power (P out )]]> 500W

[0189] Fig.23 is a waveform diagram of an output voltage and an output current of a resonant converter provided by an embodiment of the present invention, such as Fig.23 As shown, according to the resonant converter control method and the resonant converter control system of the embodiment of the present invention, the resonant converter is controlled so that the output voltage V out and output current I out Stable, and there is no obvious fluctuation in output voltage and output current before and after the working mode is switched.

[0190] Fig.24 is a partial enlarged diagram of the output voltage and output current of the resonant converter provided by the embodiment of the present invention, such as Fig.24 As shown in the figure, before and after the working mode switching, the output voltage V out and output current I out The change is small and there is no instantaneous impact.

[0191] Fig.25 is a schematic diagram of the working waveform of the resonant converter provided by the embodiment of the present invention switching from the half-bridge mode to the full-bridge mode, such as Fig.25 As shown, at the moment of switching the working mode, the voltage V Cr , the current of the resonant inductor I Lr and the current I of the magnetizing inductor Lm Stable and smooth transition without oscillation or shock. The first rectifier transistor S H1 The current I s1 and the second rectifying transistor S H2 The current I s2 Stable and smooth transition.

[0192] Fig.26 is a schematic diagram of the working waveform of the resonant converter provided by an embodiment of the present invention switching from the full-bridge mode to the half-bridge mode, such as Fig.26 As shown, at the moment of switching the working mode, the voltage V Cr , the current of the resonant inductor I Lr and the current I of the magnetizing inductor Lm Stable and smooth transition without oscillation or shock. The first rectifier transistor S H1 The current I s1 and the second rectifying transistor S H2 The current I s2 Stable and smooth transition.

[0193] Therefore, by using the resonant converter control method and the resonant converter control system of the embodiments of the present invention to control the resonant converter, the resonant converter can stabilize the output voltage when the operating mode is switched, and the resonant converter can be better controlled.

[0194] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0195] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A resonant converter control method, characterized in that: The resonant converter comprises a full-bridge inverter module, a resonant conversion module and a rectifier module; the full-bridge inverter module is connected to the resonant conversion module, and the resonant conversion module is connected to the rectifier module; the full-bridge inverter module comprises at least two bridge arms; the resonant conversion module comprises a resonant capacitor; the method is executed by a resonant converter control system; The control system is connected to the control electrode of the switch transistor of the bridge arm, and the control system includes a counter; the method includes: In each switching cycle, a target power value is determined according to an input power control amount and a compensation amount corresponding to the bridge arm; Determining a target slope control amount corresponding to a counter corresponding to the switching transistor according to the target power value, the input voltage, the circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module; wherein the working mode includes a full-bridge mode or a half-bridge mode; Determine a comparison threshold value according to the target slope control amount, the current count value of the counter corresponding to the switching transistor and the DC offset voltage of the resonant capacitor corresponding to the current working mode; wherein the counter starts counting with the DC offset voltage as the initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold value; A control signal is determined according to the actual voltage of the resonant capacitor and the comparison threshold, and the switch transistor is controlled according to the control signal.

2. The method according to claim 1, characterized in that When the working mode of the full-bridge inverter module is switched, the method further includes: The half-bridge operating mode of the full-bridge inverter module is enabled or disabled, and the DC offset voltage of the resonant capacitor is updated according to the switched operating mode, and the target slope control amount is updated according to the switched operating mode.

3. The method according to claim 1, characterized in that Before determining the target power value according to the input power control amount and the compensation amount corresponding to the bridge arm, the method further includes: Inputting the output voltage of the resonant converter, the reference voltage and the first feedback coefficient into an output voltage closed-loop controller to obtain a first deviation value; Obtaining a power feedforward value according to the output voltage, the output current of the resonant converter, the first feedback coefficient and the second feedback coefficient, and obtaining an initial target input power value according to the power feedforward value and the first deviation value; Inputting the first input voltage, the second input voltage and the sampling coefficient into the input voltage equalizing closed-loop controller to obtain a second deviation value; wherein the full-bridge inverter module includes a first bridge arm and a second bridge arm, the first input voltage is the input voltage of the first bridge arm, and the second input voltage is the input voltage of the second bridge arm; The input power control amount is determined according to the initial target input power value, the second deviation value and a normalization coefficient.

4. The method according to claim 1, characterized in that: The step of determining a target slope control amount corresponding to a counter corresponding to the switching transistor according to the target power value, the input voltage, the circuit parameters of the resonant converter and the current working mode of the full-bridge inverter module comprises: Determine the change slope control amount corresponding to each bridge arm according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor, and determine the full-bridge slope control amount and the half-bridge slope control amount according to the change slope control amount; The full-bridge slope control amount or the half-bridge slope control amount is determined as the target slope control amount according to the current working mode of the full-bridge inverter module.

5. The method according to claim 1, characterized in that Determining a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switch transistor of the bridge arm according to the control signal, comprising: When the ratio of the actual voltage to the sampling coefficient is less than the comparison threshold, controlling the first target switch transistor in the corresponding bridge arm to be turned on; When the ratio of the actual voltage to the sampling coefficient is greater than the comparison threshold, the second target switch transistor in the corresponding bridge arm is controlled to be turned on.

6. The method according to claim 5, characterized in that The method of determining a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and controlling the switch transistor of the bridge arm according to the control signal, further includes: When the ratio of the actual voltage to the sampling coefficient is equal to the comparison threshold corresponding to the first target switch transistor, the first target switch transistor corresponding to the counter is controlled to be turned off, and the second target switch transistor is controlled to be turned on, wherein the control signal of the first target switch transistor is inverted with the control signal corresponding to the second target switch transistor.

7. The method according to claim 1, characterized in that The determining the target power value according to the input power control amount and the compensation amount corresponding to the bridge arm includes: The sum of the input power control amount corresponding to the bridge arm and the compensation amount is used as the target power value corresponding to the bridge arm.

8. The method according to claim 4, characterized in that The step of determining the change slope control amount corresponding to each bridge arm according to the target power value, the input voltage of the bridge arm, the sampling coefficient, the counting step value of the counter and the capacitance of the resonant capacitor includes: Dividing the target power value by the input voltage of the corresponding bridge arm and by the capacitance of the resonant capacitor to obtain a first intermediate value; The first intermediate value is divided by the sampling coefficient and multiplied by the counting step value to obtain the change slope control amount of the corresponding bridge arm.

9. A resonant converter control system, characterized in that: The resonant converter comprises a full-bridge inverter module, a resonant conversion module and a rectifier module; the full-bridge inverter module is connected to the resonant conversion module, and the resonant conversion module is connected to the rectifier module; the full-bridge inverter module comprises at least two bridge arms; the resonant conversion module comprises a resonant capacitor; The control system is connected to the control electrode of the switch transistor of the bridge arm; the control system includes a counter; the control system includes: A target power value determination module, used to determine the target power value according to the input power control amount and compensation amount corresponding to the bridge arm in each switching cycle; a target slope control amount determination module, connected to the target power value determination module, for determining a target slope control amount corresponding to a counter corresponding to the switching transistor according to the target power value, input voltage, circuit parameters of the resonant converter and a current working mode of the full-bridge inverter module; wherein the working mode includes a full-bridge mode or a half-bridge mode; a comparison threshold determination module, connected to the target slope control amount determination module, and configured to determine a comparison threshold according to the target slope control amount, a current count value of a counter corresponding to the switching transistor, and a DC offset voltage of the resonant capacitor corresponding to a current working mode; wherein the counter starts counting with the DC offset voltage as an initial value in each switching cycle until the actual voltage of the resonant capacitor is equal to the comparison threshold; A control module is connected to the comparison threshold determination module, and is used to determine a control signal according to the actual voltage of the resonant capacitor and the comparison threshold, and control the switch transistor according to the control signal.

10. The resonant converter control system according to claim 9, characterized in that: The target power value determination module includes a first adder; The first input end of the first adder is connected to the input power control amount, and the second input end of the first adder is connected to the compensation amount; the first adder is used to add the input power control amount and the compensation amount to obtain the target power value.

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