Control method and apparatus for a resonant circuit

Abstract

The application discloses a control method and device of a resonant circuit. The method comprises the following steps: acquiring an input voltage of a clamping resonant circuit and a working mode of the clamping resonant circuit; in the case that the input voltage meets a preset condition and the working mode is a rest time of a burst working mode, controlling one switch tube in a first group of switch tubes and one switch tube in a second group of switch tubes of an inverter circuit to perform sudden switching, keeping the working state of the other switch tube in the first group of switch tubes and the second group of switch tubes unchanged, and keeping the working state of a plurality of clamping switch tubes unchanged, wherein the burst working mode is a working mode of the clamping resonant circuit in a light idle state. The application solves the technical problem of long voltage fluctuation when full-bridge mode and half-bridge mode switching is performed in the case that the burst working mode is adopted when the clamping LLC circuit is in a light idle state.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of switch converter control, in particular, to a control method and device of a resonant circuit. BACKGROUND

[0002] LLC converter can realize zero voltage switching (ZVS) of the primary side switch tube and quasi zero current switching (ZCS) of the secondary side rectifier tube, and is often used in high-frequency high-power-density power supply products. However, with the continuous development of the industry, products with wider input / output voltage range can meet market demand. When the switching frequency deviates from the resonant frequency, the farther the resonant frequency deviates, the greater the current at the primary side switch turn-off time, and the lower the efficiency. Therefore, the LLC with a conventional control scheme has the problem of narrow input voltage range. For the clamped LLC circuit, the operating frequency range is narrower than the traditional LLC in the same input voltage range, so it is more suitable for wide range applications.

[0003] In order to further improve the working efficiency of the clamped LLC circuit under wide range conditions in the prior art, a method of adopting full-bridge and half-bridge circuit structure segmented control is proposed: the clamped LLC circuit works in full-bridge mode at low voltage and works in half-bridge mode at high voltage, and the switching loss of the switch tube is reduced by switching the circuit to half-bridge mode at high voltage, thereby improving the efficiency of the LLC circuit under wide range. However, this scheme still has the following defects:

[0004] 1) This control scheme involves mode switching between full-bridge mode and half-bridge mode. Since the resonant capacitor voltage is 0 in full-bridge mode and the resonant capacitor voltage is half of the input voltage in half-bridge mode, a transition process is often needed to switch between the two modes, which can cause a long voltage fluctuation at the output end;

[0005] 2) In order to reduce the no-load power consumption as much as possible, the circuit often enters the burst working mode (abbreviated as Burst mode) when it is lightly unloaded. In this mode, the circuit alternately works in two modes of working time (i.e. driving pulse time) and rest time (i.e. no driving pulse time). The switching scheme of full-bridge mode and half-bridge mode in the prior art does not consider that the circuit works in burst working mode when it is lightly loaded;

[0006] 3) During the mode switching transition process, since the average voltage on the resonant capacitor needs to be changed, the resonant current will superimpose a direct current component to charge or discharge the resonant capacitor, so that the resonant current is not evenly positive and negative, causing the voltage stress of the clamping switch tube in the clamped LLC circuit to rise.

[0007] In the case that the LLC circuit adopts the burst mode when lightly idle, the voltage fluctuation is long when switching between the full-bridge mode and the half-bridge mode, and the voltage stress of the clamping switch tube rises. SUMMARY

[0008] The embodiments of the present application provide a control method and device of a resonant circuit to at least solve the technical problem of long voltage fluctuation when switching between the full-bridge mode and the half-bridge mode in the case that the LLC circuit adopts the burst mode when lightly idle.

[0009] According to an aspect of the embodiments of the present application, a control method of a resonant circuit is provided, which is applied to a clamping resonant circuit, the clamping resonant circuit comprising: an inverter circuit, a resonant cavity, a transformer and a rectifier circuit, wherein the inverter circuit comprises: a bridge circuit composed of four switch tubes, the four switch tubes being divided into two groups, each group comprising two switch tubes, the resonant cavity comprising: a resonant inductor, an excitation inductor, a resonant capacitor and a clamping branch composed of multiple clamping switch tubes, the control method comprising the following steps: obtaining an input voltage of the clamping resonant circuit and a working mode of the clamping resonant circuit; in the case that the input voltage meets a preset condition and the working mode is a rest time of a burst working mode, controlling one switch tube in a first group of switch tubes and one switch tube in a second group of switch tubes of the inverter circuit to perform sudden switching, the working state of the other switch tube in the first group of switch tubes and the second group of switch tubes remaining unchanged, and the working state of the multiple clamping switch tubes remaining unchanged, wherein the burst working mode is a working mode of the clamping resonant circuit in a lightly idle state.

[0010] Optionally, the working mode of the clamping resonant circuit comprises a full-bridge mode and a half-bridge mode, wherein in the case that the working mode of the clamping resonant circuit is the full-bridge mode, the first group of switch tubes and the second group of switch tubes are alternately turned on; in the case that the working mode of the clamping resonant circuit is the half-bridge mode, one switch tube in the first group of switch tubes is in a constant-on mode, one switch tube in the second group of switch tubes is in a constant-off mode, and the other switch tube in the first group of switch tubes and the second group of switch tubes is alternately turned on.

[0011] Optionally, the control of the one switch tube in the first group of switch tubes and the one switch tube in the second group of switch tubes of the inverter circuit to perform sudden switching comprises: in the case that the working mode of the clamping resonant circuit is switched from the full-bridge mode to the half-bridge mode or from the half-bridge mode to the full-bridge mode, the control of the one switch tube in the first group of switch tubes and the one switch tube in the second group of switch tubes of the inverter circuit to perform sudden switching.

[0012] Optionally, when the working mode of the clamping resonant circuit is switched from the half-bridge mode to the full-bridge mode, the abrupt switching of one of the first group of switching tubes and one of the second group of switching tubes of the inverter circuit is controlled, including: the input voltage changes from low to high to be greater than a preset threshold, the duty cycle of the one of the first group of switching tubes is abruptly changed to 0, and a constant off mode is maintained; the duty cycle of the one of the second group of switching tubes is abruptly changed to 1, and a constant on mode is maintained.

[0013] Optionally, when the working mode of the clamping resonant circuit is switched from the half-bridge mode to the full-bridge mode, the abrupt switching of one of the first group of switching tubes and one of the second group of switching tubes of the inverter circuit is controlled, including: the input voltage changes from low to high to be greater than a preset threshold, the duty cycle of the one of the first group of switching tubes is abruptly changed to 0, and a constant off mode is maintained; the duty cycle of the one of the second group of switching tubes is abruptly changed to 1, and a constant on mode is maintained.

[0014] Optionally, the method further includes: if the input voltage changes from low to high to be greater than the preset threshold and occurs during the working time of the burst working mode, or the input voltage changes from high to low to be less than the preset threshold and occurs during the working time of the burst working mode, the clamping resonant circuit does not switch the working mode temporarily until the rest time of the burst working mode, and then switches the working mode of the clamping resonant circuit.

[0015] Optionally, the preset threshold is a midpoint of an input voltage range of the clamping resonant circuit.

[0016] Optionally, the preset threshold includes a target value range, wherein the target value range is less than the input voltage range of the clamping resonant circuit, and the midpoint of the input voltage range of the clamping resonant circuit is within the target value range.

[0017] According to a further aspect of the embodiments of the present application, a control device of a resonant circuit is also provided, comprising: an acquisition module, configured to acquire an input voltage of a clamping resonant circuit and a working mode of the clamping resonant circuit, wherein the clamping resonant circuit comprises: an inverter circuit, a resonant cavity, a transformer and a rectifier circuit, wherein the inverter circuit comprises: a bridge circuit composed of four switching tubes, the four switching tubes are divided into two groups, each group comprising two switching tubes, the resonant cavity comprises: a resonant inductor, an excitation inductor, a resonant capacitor and a clamping branch composed of a plurality of clamping switching tubes; a control module, configured to, in a case where the input voltage meets a preset condition and the working mode is a rest time of a burst working mode, control one switching tube in a first group of switching tubes and one switching tube in a second group of switching tubes of the inverter circuit to perform sudden switching, a working state of another switching tube in the first group of switching tubes and the second group of switching tubes remains unchanged, and working states of the plurality of clamping switching tubes remain unchanged, wherein the burst working mode is a working mode of the clamping resonant circuit in a light idle state.

[0018] According to a further aspect of the embodiments of the present application, a nonvolatile storage medium is also provided, comprising a stored program, wherein the nonvolatile storage medium is configured to execute the control method of the resonant circuit when the program is running.

[0019] According to a further aspect of the embodiments of the present application, a processor is also provided, configured to run a program stored in a memory, wherein the program is configured to execute the control method of the resonant circuit when running.

[0020] In the embodiment of the present application, a control method of a resonant circuit is provided, which is applied to a clamping resonant circuit, the clamping resonant circuit comprising: an inverter circuit, a resonant cavity, a transformer and a rectifier circuit, wherein the inverter circuit comprises: a bridge circuit composed of four switching tubes, the four switching tubes are divided into two groups, each group comprising two switching tubes, the resonant cavity comprises: a resonant inductor, an excitation inductor, a resonant capacitor and a clamping branch composed of a plurality of clamping switching tubes, the control method comprising the following steps: obtaining an input voltage of the clamping resonant circuit and a working mode of the clamping resonant circuit; in the case that the input voltage meets a preset condition and the working mode is the rest time of the burst working mode, controlling one switching tube in the first group of switching tubes and one switching tube in the second group of switching tubes of the inverter circuit to perform sudden switching, the working state of the other switching tube in the first group of switching tubes and the second group of switching tubes remains unchanged, and the working state of the plurality of clamping switching tubes remains unchanged, wherein the burst working mode is a working mode of the clamping resonant circuit in a light idle state, through the light idle of the clamping LLC circuit, and when the burst working mode is adopted, the switching of the working mode of the clamping LLC circuit is realized by using the sudden change of the duty cycle of the primary side inverter circuit switching tube, thereby realizing the technical effect of quickly eliminating the output voltage fluctuation caused by the working mode switching of the LLC circuit, and avoiding the problem of stress rising of the clamping branch switching tube of the LLC circuit, and further solving the technical problem of long voltage fluctuation when switching between the full-bridge mode and the half-bridge mode in the case of adopting the burst working mode in the light idle state of the clamping LLC circuit. BRIEF DESCRIPTION OF DRAWINGS

[0021] The drawings described herein are used to provide further understanding of the present application, constitute a part of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute improper limitation on the present application. In the drawings:

[0022] Figure 1 It is a circuit schematic diagram of a clamping LLC circuit according to an embodiment of the present application;

[0023] Figure 2 It is a flow chart of a control method of a resonant circuit according to an embodiment of the present application;

[0024] Figure 3 It is a schematic diagram of a light idle steady state control scheme adopted by the present application;

[0025] Figure 4 It is a timing diagram when the full-bridge burst mode is switched to the half-bridge PFM mode in the rest time;

[0026] Figure 5 It is a timing diagram when the full-bridge burst mode is switched to the half-bridge PFM mode in the working time;

[0027] Figure 6Timing diagram for full bridge burst mode switching to half bridge PWM mode at rest time;

[0028] Figure 7 Timing diagram for full bridge burst mode switching to half bridge PWM mode at work time;

[0029] Figure 8 Timing diagram for full bridge burst mode switching to half bridge burst mode at rest time;

[0030] Figure 9 Timing diagram for full bridge burst mode switching to half bridge burst mode at work time;

[0031] Figure 10 Timing diagram for half bridge burst mode switching to full bridge PFM mode at rest time;

[0032] Figure 11 Timing diagram for half bridge burst mode switching to full bridge PFM mode at work time;

[0033] Figure 12 Timing diagram for half bridge burst mode switching to full bridge PWM mode at rest time;

[0034] Figure 13 Timing diagram for half bridge burst mode switching to full bridge PWM mode at work time;

[0035] Figure 14 Timing diagram for half bridge burst mode switching to full bridge burst mode at rest time;

[0036] Figure 15 Timing diagram for half bridge burst mode switching to full bridge burst mode at work time;

[0037] Figure 16 Figure 1 is a structural block diagram of a control device of a resonant circuit according to an embodiment of the present application. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0039] It should be noted that the terms "first", "second" and the like in the description and in the claims of the present application as well as above-mentioned drawings mean for distinguishing between similar objects and not necessarily for describing a specific sequential or chronological order. It is to be understood that the data shown in the figures can be interchanged, where appropriate, so that the embodiments of the present application described herein can be carried out in other than the order shown in the figures. Furthermore, the terms "comprise" and "include" and their conjugates, as used in the present description and in the claims, do not exclude the presence of elements or steps other than those listed in the description or claims. The terminology used herein for the purpose of describing particular embodiments should not be read as indicating that the terminology is used as a limitation to the spirit or scope of the application.

[0040] According to the embodiments of the present application, an embodiment of a control method of a resonant circuit is provided. It should be noted that the steps shown in the flowcharts of the drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowcharts, in some cases, the steps shown or described herein can be executed in an order different from that shown herein.

[0041] The control method of the resonant circuit provided by the embodiments of the present application is applied to a clamped resonant circuit, which includes an inverter circuit, a resonant cavity, a transformer and a rectifier circuit. The inverter circuit includes a bridge circuit composed of four switching tubes, the four switching tubes are divided into two groups, each group includes two switching tubes. The resonant cavity includes a resonant inductor, an excitation inductor, a resonant capacitor and a clamping branch composed of two clamping switching tubes,

[0042] Figure 1 is a circuit schematic diagram of a clamped LLC circuit according to the embodiments of the present application, as shown in Figure 1 The clamped LLC circuit includes an inverter circuit 101, an LLC resonant cavity 102, a transformer 103 and a secondary side rectifier network 104. In the figure, VIN is the input power supply of the clamped LLC resonant converter, and Rload is the output load of the clamped LLC resonant converter.

[0043] The inverter circuit 101 includes a full-bridge inverter circuit composed of switching tube S1, switching tube S2, switching tube S3 and switching tube S4; the LLC resonant cavity 102 includes resonant inductor Lr, excitation inductor Lm and resonant capacitor Cr, and the clamping branch composed of clamping switching tube S5 and clamping switching tube S6; the transformer 103 includes transformer TX1 composed of primary winding P1 and secondary winding S1 and S2; the rectifier network 104 includes a full-wave rectifier circuit composed of synchronous rectifier SR1 and SR2, and an output filter capacitor Cout.

[0044] The drain of the switch tube S1 and the drain of the switch tube S3 are connected together as the input positive terminal of the LLC resonant converter, for connecting the positive terminal of the input power Vin, the source of the switch tube S1 is connected to the drain of the switch tube S2 and one end of the resonant capacitor Cr, the other end of the resonant capacitor Cr is connected to one end of the resonant inductor Lr and the drain of the clamping switch tube S5, the other end of the resonant inductor Lr is connected to one end of the excitation inductor Lm and one end of the primary winding P1 of the transformer TX1, the other end of the primary winding P1 of the transformer TX1 is connected to the other end of the excitation inductor Lm, the source of the switch tube S3, the drain of the switch tube S4 and the drain of the clamping switch tube S6, the source of the clamping switch tube S5 and the source of the clamping switch tube S6 are connected together, the source of the switch tube S4 and the source of the switch tube S2 are connected together as the input negative terminal of the LLC resonant converter, for connecting the negative terminal of the input power Vin; one end of the secondary winding S1 of the transformer TX1 is connected to the drain of the secondary synchronous rectifier SR2, the source of the synchronous rectifier SR2, the source of the synchronous rectifier SR1 and one end of the output filter capacitor Cout are connected together as the output negative terminal of the LLC resonant converter, for connecting the negative terminal of the output load Ro, the other end of the secondary winding S1 of the transformer TX1, one end of the secondary winding S2 of the transformer TX1 and the other end of the output filter capacitor Co are connected together as the output positive terminal of the LLC resonant converter, for connecting the positive terminal of the output load Ro, the other end of the secondary winding S2 of the transformer TX1 is connected to the drain of the secondary synchronous rectifier SR1. The primary winding P1 of the transformer TX1 and one end of the secondary windings S1 and S2 are the same name terminals, and the other ends of the primary winding P1 and the secondary windings S1 and S2 are the same name terminals.

[0045] It should be noted that, Figure 1 The circuit shown also includes but is not limited to the following modifications:

[0046] (1) The secondary rectifier network 104 is replaced by a bridge rectifier structure composed of four switch tubes or four diodes, or the switch tubes in the secondary rectifier network are directly replaced by diodes;

[0047] (2) The positions of the resonant capacitor Cr and the resonant inductor Lr are exchanged.

[0048] Figure 2 is a flow chart of a control method of a resonant circuit according to an embodiment of the present application, as shown, the method comprises the following steps: Figure 2 The method comprises the following steps:

[0049] In step S202, the input voltage of the clamping resonant circuit and the working mode of the clamping resonant circuit are obtained;

[0050] Step S204, in the case that the input voltage meets the preset condition and the working mode is the rest time of the burst working mode, one of the first group of switch tubes and one of the second group of switch tubes of the inverter circuit are controlled to perform sudden switching, the working state of the other switch tube of the first group of switch tubes and the second group of switch tubes remains unchanged, and the working state of the plurality of clamping switch tubes remains unchanged, wherein the burst working mode is a working mode in the light idle state of the clamping resonant circuit.

[0051] It should be noted that the switch tubes in the inverter circuit are divided into two groups, each group containing two switch tubes, which alternately conduct the primary side circuit of the LLC resonant circuit. Referring to Figure 2 , S1 and S4 are the first group, and S2 and S3 are the second group (the order can be exchanged, S1 and S4 are the second group, and S2 and S3 are the first group).

[0052] In this step, by taking the input voltage as the judgment condition for switching between the full-bridge mode and the half-bridge mode, if the input voltage changes from low to high by more than a set threshold, or changes from high to low by less than a set threshold, and the circuit works in the burst working mode, one of the first group of switch tubes and one of the second group of switch tubes of the primary side inverter circuit directly perform sudden switching, the other switch tube of the two groups of switch tubes remains closed-loop control, and the clamping switch tube remains closed-loop control.

[0053] In addition, it should be noted that the burst working mode is a working mode in the light idle state of the clamping resonant circuit. In order to reduce the idle power consumption as much as possible when the circuit works in the light idle state, the circuit often enters the burst working mode, which is referred to as Burst mode. In this mode, the circuit works alternately in the working time (i.e., the time when the driving pulse is output) and the rest time (i.e., the time when the driving pulse is not output).

[0054] Through the above steps, by clamping the LLC circuit in the light idle state and using the burst working mode, the working mode of the clamping LLC circuit is switched by using the sudden change of the duty cycle of the switch tube of the primary side inverter circuit, thereby realizing the technical effect of quickly eliminating the output voltage fluctuation caused by the working mode switching of the LLC circuit and avoiding the problem of stress rising of the clamping branch switch tube of the LLC circuit.

[0055] According to an optional embodiment of the present application, the working mode of the clamping resonant circuit includes a full-bridge mode and a half-bridge mode, wherein in the case that the working mode of the clamping resonant circuit is the full-bridge mode, the first group of switch tubes and the second group of switch tubes are alternately conducted; in the case that the working mode of the clamping resonant circuit is the half-bridge mode, one of the first group of switch tubes is in the always-on mode, one of the second group of switch tubes is in the always-off mode, and the other switch tube of the first group of switch tubes and the second group of switch tubes is alternately conducted.

[0056] The LLC resonant circuit works in a light idle condition. By taking the input voltage as a judgment condition, when the input voltage is lower than a preset threshold, the system works in a full-bridge mode, two groups of switch tubes in the primary side inverter circuit are alternately turned on, and the circuit structure is a full-bridge structure. When the input voltage is higher than the preset threshold, the system works in a half-bridge mode, one switch tube in the first group of switch tubes in the primary side inverter circuit is in a constant-on mode and one switch tube in the second group of switch tubes is in a constant-off mode, and the other switch tubes in the two groups of switch tubes are alternately turned on.

[0057] According to another optional embodiment of the present application, the step S204 of controlling one switch tube in the first group of switch tubes and one switch tube in the second group of switch tubes of the inverter circuit to perform abrupt switching includes: when the working mode of the clamping resonant circuit is switched from the full-bridge mode to the half-bridge mode or from the half-bridge mode to the full-bridge mode, controlling one switch tube in the first group of switch tubes and one switch tube in the second group of switch tubes of the inverter circuit to perform abrupt switching.

[0058] It should be noted that the control of one switch tube in the first group of switch tubes and one switch tube in the second group of switch tubes of the inverter circuit to perform abrupt switching refers to the process of switching the working mode of the clamping resonant circuit from the full-bridge mode to the half-bridge mode or from the half-bridge mode to the full-bridge mode.

[0059] In some optional embodiments of the present application, when the working mode of the clamping resonant circuit is switched from the full-bridge mode to the half-bridge mode, the control of one switch tube in the first group of switch tubes and one switch tube in the second group of switch tubes of the inverter circuit to perform abrupt switching includes the following steps: the input voltage changes from low to high to be greater than the preset threshold, the duty cycle of one switch tube in the first group of switch tubes is abruptly changed to 0 and remains in the constant-off mode; the duty cycle of one switch tube in the second group of switch tubes is abruptly changed to 1 and remains in the constant-on mode.

[0060] When the working mode of the clamping resonant circuit is switched from the full-bridge mode to the half-bridge mode, the change of the input voltage from low to high greater than the set threshold occurs in the rest time of the burst working mode, one switch tube in one group of switch tubes of the primary side inverter circuit has a duty cycle abruptly changed to 0 and remains in the constant-off mode, and the other switch tube is still controlled by the system in a closed loop; one switch tube in the other group of switch tubes has a duty cycle abruptly changed to 1 and remains in the constant-on mode, and the other switch tube is still controlled by the system in a closed loop; the clamping switch tube is always controlled in a closed loop.

[0061] According to an optional embodiment of the present application, when the working mode of the clamping resonant circuit is switched from the half-bridge mode to the full-bridge mode, one of the switches in the first group of switches and one of the switches in the second group of switches of the inverter circuit are controlled to perform abrupt switching, including the following steps: the input voltage changes from high to low to be less than a preset threshold, the duty cycle of the switch that remains in the always-on mode is abruptly changed to 0, and the switch is subsequently controlled by the system closed loop control; the switch that remains in the always-off mode is abruptly changed to be controlled by the system closed loop control.

[0062] When the working mode of the clamping resonant circuit is switched from the half-bridge mode to the full-bridge mode, the input voltage changes from high to low to be less than a preset threshold, which occurs during the rest time of the burst working mode, the duty cycle of the always-on switch in the primary side inverter circuit is abruptly changed to 0 and subsequently becomes closed loop control, and all other switches are controlled by the closed loop control; the clamping switch is always controlled by the closed loop control.

[0063] In an optional embodiment, the above method further includes: if the input voltage changes from low to high to be greater than the preset threshold and occurs during the working time of the burst working mode, or the input voltage changes from high to low to be less than the preset threshold and occurs during the working time of the burst working mode, the clamping resonant circuit does not perform mode switching until the rest time of the burst working mode, and then the working mode of the clamping resonant circuit is switched.

[0064] It should be noted that during the process of switching the working mode of the clamping resonant circuit from the full-bridge mode to the half-bridge mode, the input voltage changes from low to high to be greater than a preset threshold, which occurs during the working time of the burst working mode, and the circuit does not trigger mode switching until the rest time of the burst working mode.

[0065] During the process of switching the working mode of the clamping resonant circuit from the half-bridge mode to the full-bridge mode, the input voltage changes from high to low to be less than a preset threshold, which occurs during the working time of the burst working mode, and the circuit does not trigger mode switching until the rest time of the burst working mode.

[0066] According to an optional embodiment of the present application, the preset threshold is the midpoint of the input voltage range of the clamping resonant circuit.

[0067] In the embodiments provided in the present application, the preset threshold is usually set at the midpoint of the gain range required by the clamping LLC resonant circuit, so as to achieve the optimal overall efficiency of the circuit in a wide range.

[0068] For example, the input voltage range of the clamping LLC resonant circuit is 0-20V, and the preset threshold is preferably 10V.

[0069] It should be noted that the preset threshold can also be any voltage value between 0-20V.

[0070] According to another optional embodiment of this application, the preset threshold value includes a target value range, wherein the target value range is smaller than the input voltage range of the clamping resonant circuit, and the midpoint of the input voltage range of the clamping resonant circuit is located within the target value range.

[0071] The above-mentioned preset threshold settings usually include hysteresis to avoid accidental triggering of mode switching when the prototype is in steady-state operation.

[0072] As mentioned above, the input voltage range of the clamping LLC resonant circuit is 0 to 20V, and the preset threshold is preferably set to 10V. In actual implementation, this threshold is usually set with hysteresis, for example, the preset threshold is located at any voltage value between 9V and 11V, which can avoid accidental triggering of mode switching when the prototype is operating in steady state.

[0073] The method proposed in this application achieves the switching of the operating mode of the clamping LLC resonant circuit by abruptly changing the duty cycle of the primary-side inverter circuit switching transistors. This switching method requires no transient process, and the output fluctuations caused by the switching process can be recovered in a short time. Conventional switching schemes with transient processes cause stress on the clamping branch switching transistors because the mode switching occurs when the inverter circuit switches, resulting in a DC component superimposed on the resonant cavity current. The method provided in this application solves the problem of stress increase on the clamping branch switching transistors by operating the normally conducting switching transistors in the half-bridge mode during the rest period of the sudden operating mode. During the rest period, the resonant capacitor is charged and discharged. When switching from the full-bridge mode to the half-bridge mode, the resonant capacitor is charged, and when switching from the half-bridge mode to the full-bridge mode, the resonant capacitor is discharged. The charging and discharging of the resonant capacitor is completed before the switching transistors of the primary-side inverter circuit switch, thus solving the problem of stress increase on the clamping branch switching transistors. Moreover, since the mode switching occurs during the circuit's rest period, the primary side does not transfer energy to the secondary side, significantly reducing the impact of mode switching on output voltage fluctuations.

[0074] The following is combined Figure 1 The clamping LLC resonant circuit shown illustrates the method described above in this application:

[0075] In this application, the input voltage range of the clamping LLC resonant circuit is divided into 6 regions, such as... Figure 3 The diagram shows full-bridge PFM, full-bridge PWM, full-bridge Burst, half-bridge PFM, half-bridge PWM, and half-bridge Burst, respectively.

[0076] Table 1 shows the light no-load stability control schemes adopted in this application. The control schemes for each mode are described below:

[0077] Table 1

[0078]

[0079]

[0080] Full-bridge PFM mode: switch S1 drive duty cycle is 50%, the frequency is determined by closed loop; switch S2 drive frequency and duty cycle with S1 same, phase difference 180°; switch S3 drive with S2 same; switch S4 drive with S1 same; clamp switch S5 constant off, clamp switch S6 constant off.

[0081] Full-bridge PWM mode: switch S1 drive working frequency is resonance frequency, duty cycle is determined by closed loop; switch S2 drive frequency and duty cycle with S1 same, phase difference 180°; switch S3 drive with S2 same; switch S4 drive with S1 same; clamp switch S5 drive with S1 complementary; clamp switch S6 drive with S2 complementary.

[0082] Full-bridge Burst working time: switch S1 drive working frequency is resonance frequency, duty cycle is determined by closed loop; switch S2 drive frequency and duty cycle with S1 same, phase difference 180°; switch S3 drive with S2 same; switch S4 drive with S1 same; clamp switch S5 drive with S1 complementary; clamp switch S6 drive with S2 complementary.

[0083] Full-bridge Burst rest time: all switches in primary side constant off.

[0084] Half-bridge PFM mode: switch S1 drive duty cycle is 50%, the frequency is determined by closed loop; switch S2 drive frequency and duty cycle with S1 same, phase difference 180°; switch S3 constant off; switch S4 constant on; clamp switch S5 constant off, clamp switch S5 constant off.

[0085] Half-bridge PWM mode: switch S1 drive working frequency is resonance frequency, duty cycle is determined by closed loop; switch S2 drive frequency and duty cycle with S1 same, phase difference 180°; switch S3 constant off; switch S4 constant on; clamp switch S5 drive with S1 complementary; clamp switch S6 drive with S2 complementary.

[0086] Half-bridge Burst working time: switch S1 drive working frequency is resonance frequency, duty cycle is determined by closed loop; switch S2 drive frequency and duty cycle with S1 same, phase difference 180°; switch S3 constant off; switch S4 constant on; clamp switch S5 drive with S1 complementary; clamp switch S6 drive with S2 complementary.

[0087] Full-bridge Burst rest time: all switches in primary side constant off.

[0088] The light no-load switching control scheme proposed in this application is applicable to the switching from full-bridge Burst mode to any half-bridge mode, and also applicable to the switching from half-bridge Burst mode to any full-bridge mode.

[0089] The timing diagram for the switch from the full-bridge burst mode to the half-bridge PFM mode during the rest period is shown below. Figure 4 The signals Vgs1, Vgs2, Vgs3, Vgs4, Vgs5, and Vgs6 are the drive signals for switches S1, S2, S3, S4, S5, and S6, respectively. t0-t1 is the working time, and t1-t2 is the rest time. During the rest time, mode switching is triggered. The duty cycle of switch S3 suddenly changes to 0 and remains normally off, while the duty cycle of switch S4 suddenly changes to 1 and remains normally on. All other primary-side switches maintain closed-loop control. In PFM mode, the clamping branch is not on, and the duty cycle of the clamping switch is 0.

[0090] The timing diagram for the transition from full-bridge burst mode to half-bridge PFM mode during operating time is shown below. Figure 5 The meaning of all signals is the same as Figure 4 Consistent, t0-t1 is the working time, t1-t2 is the rest time. During the working time, the mode switching is triggered. All switches in the circuit do not operate until the rest time is entered. The duty cycle of switch S3 suddenly changes to 0 and remains normally off. The duty cycle of switch S4 suddenly changes to 1 and remains normally on. All other primary-side switches maintain closed-loop control. In PFM mode, the clamping branch does not conduct, and the duty cycle of the clamping switch is 0.

[0091] The timing diagram for the switch from full-bridge burst mode to half-bridge PWM mode during the rest period is shown below. Figure 6 The meaning of all signals is the same as Figure 4 Consistent, t0-t1 is the working time, t1-t2 is the rest time. During the rest time, mode switching is triggered. The duty cycle of switch S3 suddenly changes to 0 and remains normally off, the duty cycle of switch S4 suddenly changes to 1 and remains normally on, and all other primary-side switches maintain closed-loop control.

[0092] The timing diagram for the switch from full-bridge burst mode to half-bridge PWM mode during operation is shown below. Figure 7 The meaning of all signals is the same as Figure 4 The circuit is consistent, with t0-t1 being the working time and t1-t2 being the rest time. During the working time, mode switching is triggered, and all switches in the circuit remain inactive until the rest time begins. Switch S3's duty cycle abruptly drops to 0 and remains normally off, while switch S4's duty cycle abruptly drops to 1 and remains normally on. All other primary-side switches maintain closed-loop control.

[0093] The timing diagram for the transition from full-bridge burst mode to half-bridge burst mode during the rest period is shown below. Figure 8 The meaning of all signals is the same as Figure 4Consistent with the above, t0-t1 is the working time, t1-t2 is the rest time, and the mode switching is triggered in the rest time. The duty ratio of switch S3 suddenly changes to 0 and is always off, and the duty ratio of switch S4 suddenly changes to 1 and is always on. All other primary side switches are kept in closed-loop control and continue to work in the burst working mode.

[0094] The timing chart of the full-bridge burst mode switching to the half-bridge burst mode in the working time is shown in FIG. 6. Figure 9 , where all signal meanings are consistent with Figure 4 Consistent with the above, t0-t1 is the working time, t1-t2 is the rest time, and the mode switching is triggered in the working time. All switches of the circuit are not actuated until entering the rest time. The duty ratio of switch S3 suddenly changes to 0 and is always off, and the duty ratio of switch S4 suddenly changes to 1 and is always on. All other primary side switches are kept in closed-loop control and continue to work in the burst working mode.

[0095] The timing chart of the half-bridge burst mode switching to the full-bridge PFM mode in the rest time is shown in FIG. 7. Figure 10 , where all signal meanings are consistent with Figure 4 Consistent with the above, t0-t1 is the working time, t1-t2 is the rest time, and the mode switching is triggered in the rest time. The duty ratio of switch S3 suddenly changes back to the closed-loop control consistent with S1, and the duty ratio of switch S4 suddenly changes to 0 and changes back to the closed-loop control consistent with S1 when the next pulse is fired. All other primary side switches are kept in closed-loop control. The clamping branch is not conductive in the PFM mode, and the duty ratio of the clamping switch is 0.

[0096] The timing chart of the half-bridge burst mode switching to the full-bridge PFM mode in the working time is shown in FIG. 8. Figure 11 , where all signal meanings are consistent with Figure 4 Consistent with the above, t0-t1 is the working time, t1-t2 is the rest time, and the mode switching is triggered in the working time. All switches of the circuit are not actuated until entering the rest time. The duty ratio of switch S3 suddenly changes back to the closed-loop control consistent with S1, and the duty ratio of switch S4 suddenly changes to 0 and changes back to the closed-loop control consistent with S1 when the next pulse is fired. All other primary side switches are kept in closed-loop control. The clamping branch is not conductive in the PFM mode, and the duty ratio of the clamping switch is 0.

[0097] The timing chart of the half-bridge burst mode switching to the full-bridge PWM mode in the rest time is shown in FIG. 9. Figure 12 , where all signal meanings are consistent with Figure 4 Consistent with the above, t0-t1 is the working time, t1-t2 is the rest time, and the mode switching is triggered in the rest time. The duty ratio of switch S3 suddenly changes back to the closed-loop control consistent with S1, and the duty ratio of switch S4 suddenly changes to 0 and changes back to the closed-loop control consistent with S1 when the next pulse is fired. All other primary side switches are kept in closed-loop control.

[0098] Half bridge burst mode switching to full bridge PWM mode timing diagram see Figure 13 Where all signal meanings are consistent with Figure 4 t0-t1 is the working time, t1-t2 is the rest time, the mode switching is triggered in the working time, all switch tubes are not in action until entering the rest time, the duty cycle of switch tube S3 mutates back to the closed loop control consistent with S1, the duty cycle of switch tube S4 mutates to 0 and mutates back to the closed loop control consistent with S1 when the next pulse is fired, and all other primary side switch tubes remain in the closed loop control.

[0099] Half bridge burst mode switching to full bridge burst mode timing diagram see Figure 14 Where all signal meanings are consistent with Figure 4 t0-t1 is the working time, t1-t2 is the rest time, the mode switching is triggered in the rest time, the duty cycle of switch tube S3 mutates back to the closed loop control consistent with S1, the duty cycle of switch tube S4 mutates to 0 and mutates back to the closed loop control consistent with S1 when the next pulse is fired, and all other primary side switch tubes remain in the closed loop control and continue to work in the burst mode.

[0100] Half bridge burst mode switching to full bridge burst mode timing diagram see Figure 15 Where all signal meanings are consistent with Figure 4 t0-t1 is the working time, t1-t2 is the rest time, the mode switching is triggered in the working time, all switch tubes are not in action until entering the rest time, the duty cycle of switch tube S3 mutates back to the closed loop control consistent with S1, the duty cycle of switch tube S4 mutates to 0 and mutates back to the closed loop control consistent with S1 when the next pulse is fired, and all other primary side switch tubes remain in the closed loop control and continue to work in the burst mode.

[0101] According to all the above cases, the switching method of the full bridge mode and the half bridge mode adopts sudden switching, without transition process, and the output fluctuation caused by the switching process can be recovered in a short time. By controlling the switching tube action logic under different conditions, the charging and discharging of the resonant capacitor is completed in the rest time of the burst mode, solving the problem of rising stress of the clamping switch tube caused by the presence of DC component in the primary side inverter circuit switching action. And since the mode switching occurs in the rest time of the burst mode, the primary side does not transfer energy to the secondary side, so the output voltage fluctuation caused by the mode switching is very small.

[0102] The above control scheme provided by the application can be realized by analog control or digital control.

[0103] Figure 16 is a structural block diagram of a control device of a resonant circuit according to an embodiment of the application, asFigure 16 As shown in the figure, the device comprises:

[0104] The acquisition module 1600 is configured to acquire an input voltage of the clamping resonant circuit and an operating mode of the clamping resonant circuit, wherein the clamping resonant circuit comprises an inverter circuit, a resonant cavity, a transformer and a rectifier circuit, the inverter circuit comprises a bridge circuit composed of four switching tubes, the four switching tubes are divided into two groups, each group comprising two switching tubes, the resonant cavity comprises a resonant inductor, an excitation inductor, a resonant capacitor and a clamping branch composed of a plurality of clamping switching tubes.

[0105] The control module 1602 is configured to, in a case where the input voltage meets a preset condition and the operating mode is a rest time of a burst operating mode, control one switching tube in a first group of switching tubes and one switching tube in a second group of switching tubes of the inverter circuit to perform sudden switching, the working state of another switching tube in the first group of switching tubes and the second group of switching tubes remains unchanged, and the working state of the plurality of clamping switching tubes remains unchanged, wherein the burst operating mode is a kind of operating mode in a light idle state of the clamping resonant circuit.

[0106] It should be noted that, Figure 16 The preferred embodiments of the embodiments shown can be referred to Figure 1 The related description of the embodiments shown will not be repeated here.

[0107] The embodiments of the present application also provide a non-volatile storage medium, the non-volatile storage medium comprises a stored program, wherein when the program runs, the device where the non-volatile storage medium is located executes the above control method of the resonant circuit.

[0108] The non-volatile storage medium is used to store a program for performing the following functions: acquiring an input voltage of a clamping resonant circuit and an operating mode of the clamping resonant circuit; in a case where the input voltage meets a preset condition and the operating mode is a rest time of a burst operating mode, controlling one switching tube in a first group of switching tubes and one switching tube in a second group of switching tubes of the inverter circuit to perform sudden switching, the working state of another switching tube in the first group of switching tubes and the second group of switching tubes remains unchanged, and the working state of the plurality of clamping switching tubes remains unchanged, wherein the burst operating mode is a kind of operating mode in a light idle state of the clamping resonant circuit.

[0109] The embodiments of the present application also provide a processor, the processor is used to run the program stored in the memory, wherein when the program runs, the above control method of the resonant circuit is executed.

[0110] The processor is configured to run a program to perform the following functions: obtaining an input voltage of the clamping resonant circuit and an operating mode of the clamping resonant circuit; in the case that the input voltage meets a preset condition and the operating mode is a rest time of a burst operating mode, controlling one switch tube in the first group of switch tubes and one switch tube in the second group of switch tubes of the inverter circuit to perform abrupt switching, keeping the operating state of the other switch tube in the first group of switch tubes and the second group of switch tubes unchanged, and keeping the operating state of the plurality of clamping switch tubes unchanged, wherein the burst operating mode is one operating mode of the clamping resonant circuit in a light idle state.

[0111] The sequence numbers of the embodiments of the present application are only for description, and do not represent the advantages and disadvantages of the embodiments.

[0112] In the above-described embodiments of the present application, the description of each embodiment has its own focus, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0113] In the several embodiments provided by the present application, it should be understood that the disclosed technology can be implemented in other ways. Of course, the device embodiment described above is only illustrative, and for example, the division of units can be a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, unit or module, and can be electrical or other forms.

[0114] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on multiple units. According to actual needs, part or all of the units can be selected to achieve the purpose of the embodiment scheme.

[0115] In addition, each functional unit in each embodiment of the present application can be integrated in one processing unit, or each unit can exist physically, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of a software functional unit.

[0116] The integrated unit, if implemented in the form of a software function unit and sold or used as an independent product, can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application or the part that essentially contributes to the related art or the whole or part of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server or a network device, etc.) to execute all or part of the steps of the method described in the embodiments of the present application. The aforementioned storage medium includes a U disk, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and various media that can store program codes.

[0117] The above only describes the preferred embodiments of the present application. It should be noted that, for those skilled in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, which should also be considered as the protection scope of the present application.

Claims

1. A control method for a resonant circuit, characterized in that, This method is applied to a clamping resonant circuit, which includes an inverter circuit, a resonant cavity, a transformer, and a rectifier circuit. The inverter circuit includes a bridge circuit composed of four switching transistors, divided into two groups of two transistors each. The resonant cavity includes a resonant inductor, a magnetizing inductor, a resonant capacitor, and a clamping branch composed of multiple clamping switching transistors. The control method includes the following steps: Obtain the input voltage of the clamping resonant circuit and the operating mode of the clamping resonant circuit; When the input voltage meets the preset conditions and the operating mode is the rest period of the sudden operating mode, one switch in the first group and one switch in the second group of the inverter circuit are controlled to switch abruptly. The operating state of the other switch in the first group and the second group remains unchanged, and the operating state of the plurality of clamping switches remains unchanged. When the operating mode of the clamping resonant circuit switches from full-bridge mode to half-bridge mode, the input voltage changes from low to high to greater than a preset threshold. The duty cycle of one switch in the first group is controlled to abruptly change to 0 and remain in the normally off mode; the duty cycle of one switch in the second group is controlled to abruptly change to 1 and remain in the normally on mode. The sudden operating mode is an operating mode of the clamping resonant circuit under light no-load conditions.

2. The method according to claim 1, characterized in that, The operating modes of the clamping resonant circuit include full-bridge mode and half-bridge mode, wherein, When the operating mode of the clamping resonant circuit is the full-bridge mode, the first group of switching transistors and the second group of switching transistors are turned on alternately. When the operating mode of the clamping resonant circuit is the half-bridge mode, one of the switches in the first group is in the normally on mode, one of the switches in the second group is in the normally off mode, and the other switch in the first group and the other switch in the second group are alternately turned on.

3. The method according to claim 2, characterized in that, Controlling a sudden switching of one switch in the first group and one switch in the second group of the inverter circuit includes: When the operating mode of the clamping resonant circuit switches from the full-bridge mode to the half-bridge mode, or from the half-bridge mode to the full-bridge mode, one of the switching transistors in the first group and one of the switching transistors in the second group of the inverter circuit are controlled to switch abruptly.

4. The method according to claim 1, characterized in that, When the operating mode of the clamping resonant circuit switches from the half-bridge mode to the full-bridge mode, controlling one switch in the first group and one switch in the second group of the inverter circuit to switch abruptly includes: When the input voltage changes from high to low and falls below the preset threshold, the duty cycle of the switch maintaining the normally on mode is abruptly reduced to 0 and the switch is subsequently controlled by the system closed-loop control; the switch maintaining the normally off mode is abruptly controlled by the system closed-loop control.

5. The method according to claim 1, characterized in that, The method further includes: If the input voltage changes from low to high to greater than the preset threshold and occurs during the working time of the sudden working mode, or if the input voltage changes from high to low to less than the preset threshold and occurs during the working time of the sudden working mode, the clamping resonant circuit will not switch modes until it enters the rest time of the sudden working mode, at which point the working mode of the clamping resonant circuit will be switched.

6. The method according to any one of claims 4 to 5, characterized in that, The preset threshold value is the midpoint of the input voltage range of the clamping resonant circuit.

7. The method according to any one of claims 4 to 5, characterized in that, The preset threshold value includes a target value range, wherein the target value range is smaller than the input voltage range of the clamping resonant circuit, and the midpoint of the input voltage range of the clamping resonant circuit is located within the target value range.

8. A control device for a resonant circuit, characterized in that, include: The acquisition module is used to acquire the input voltage of the clamping resonant circuit and the operating mode of the clamping resonant circuit. The clamping resonant circuit includes an inverter circuit, a resonant cavity, a transformer, and a rectifier circuit. The inverter circuit includes a bridge circuit composed of four switching transistors, which are divided into two groups, each group including two switching transistors. The resonant cavity includes a resonant inductor, a magnetizing inductor, a resonant capacitor, and a clamping branch composed of multiple clamping switching transistors. The control module is configured to, when the input voltage meets preset conditions and the operating mode is a rest period of a sudden operating mode, control one switch in the first group of switches and one switch in the second group of switches in the inverter circuit to abruptly switch, while the operating state of the other switch in the first group and the second group remains unchanged, and the operating states of the plurality of clamping switches remain unchanged. Specifically, when the operating mode of the clamping resonant circuit switches from full-bridge mode to half-bridge mode, the input voltage changes from low to high until it exceeds a preset threshold. The module then controls the duty cycle of one switch in the first group to abruptly change to 0 and maintain a normally off mode; and controls the duty cycle of one switch in the second group to abruptly change to 1 and maintain a normally on mode. The sudden operating mode is an operating mode of the clamping resonant circuit under light no-load conditions.

9. A non-volatile storage medium, characterized in that, The non-volatile storage medium includes a stored program, wherein, when the program is executed, the device containing the non-volatile storage medium is controlled to perform the control method of the resonant circuit according to any one of claims 1 to 7.

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