Switch control method, switch control circuit and electronic equipment

Abstract

The invention discloses a switch control method, a switch control circuit and electronic equipment, and is applied to switch control of a resonant conversion circuit, and the switch control method comprises the steps: obtaining a state feedback signal in the resonant conversion circuit; determining the current load state of the resonant conversion circuit by using the state feedback signal; generating a high-frequency switching signal and / or a low-frequency gap signal based on the load state; and adjusting the switching state of the resonant conversion circuit by using the high-frequency switching signal or the low-frequency gap signal so as to adjust the output voltage of the resonant conversion circuit. Through the above mode, the switching control method can reasonably select the high-frequency switching signal or the low-frequency gap signal to control the resonant conversion circuit in response to different load states of the resonant conversion circuit, so that the efficiency of the resonant conversion circuit in light load and no load and the stability of the output voltage and the DC gain curve state can be effectively ensured; and the problem of overlarge ripples caused by control delay in intermittent wave transmission of a hysteresis control mode is avoided.

Description

Technical Field

[0001] The present application relates to the field of circuit control technology, and in particular to a switch control method, a switch control circuit and an electronic device. Background Art

[0002] Nowadays, LLC (including an additional inductance (L) in series with two other components, inductor L and capacitor (C)) converter is a highly efficient resonant topology, which is widely used in the field of medium and high power supply due to its soft switching characteristics, wide gain range and other advantages. However, there are still some challenges in how to achieve more reasonable adaptive control of LLC converters, especially when the LLC converter is lightly loaded or no-loaded, the excessively high switching frequency of the LLC converter's driving control signal will be detrimental to the improvement of efficiency; and when lightly loaded, the discharge process of the parasitic capacitor in the LLC converter after being charged has a greater impact on the LLC converter output, which will change the state of the DC gain curve and cause its output voltage to be out of control. Summary of the invention

[0003] The main technical problem solved by the present application is to provide a switch control method, a switch control circuit and an electronic device, which can solve the problem of efficiency of the control of the LLC converter implemented in the prior art under light load and no-load conditions, and the problem that the state of the DC gain curve will be changed under light load, resulting in the output voltage being out of control.

[0004] In order to solve the above technical problems, a technical solution adopted in the present application is: to provide a switch control method, which is applied to the switch control of a resonant conversion circuit, wherein the switch control method includes: obtaining a state feedback signal in the resonant conversion circuit; determining the current load state of the resonant conversion circuit using the state feedback signal; generating a high-frequency switch signal and / or a low-frequency gap signal based on the load state; and adjusting the switch state of the resonant conversion circuit using the high-frequency switch signal or the low-frequency gap signal to adjust the output voltage of the resonant conversion circuit.

[0005] Among them, the state feedback signal includes the output voltage, and the step of using the state feedback signal to determine the current load state of the resonant conversion circuit includes: using the difference between the output voltage and the target output voltage to obtain the measured switching frequency; comparing the measured switching frequency with the maximum switching frequency of the resonant conversion circuit to obtain the load state.

[0006] Among them, the high-frequency switching signal and the low-frequency gap signal are pulse width modulation signals, and the step of comparing the measured switching frequency with the maximum switching frequency of the resonant conversion circuit to obtain the load state includes: judging whether the measured switching frequency is greater than the maximum switching frequency; the step of generating the high-frequency switching signal and / or the low-frequency gap signal based on the load state includes: if the measured switching frequency is less than or equal to the maximum switching frequency, using the measured switching frequency to generate the high-frequency switching signal and the low-frequency gap signal, and making the duty cycle of the low-frequency gap signal 1; performing a logical AND operation on the high-frequency switching signal and the low-frequency gap signal to obtain a drive control signal; using the high-frequency switching signal or the low-frequency gap signal to adjust the switch state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit includes: using the drive control signal to adjust the switch state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit.

[0007] The switch control method further includes: if the measured switching frequency is greater than the maximum switching frequency, generating a high-frequency switching signal using the maximum switching frequency; and generating and adjusting the duty cycle of the low-frequency gap signal using the measured switching frequency.

[0008] Among them, the step of generating and adjusting the duty cycle of the low-frequency gap signal by measuring the switching frequency includes: adjusting the signal period of the low-frequency gap signal by measuring the switching frequency; or, adjusting the sealing time and / or transmitting time of the low-frequency gap signal by measuring the switching frequency.

[0009] The state feedback signal includes a resonant current, and the step of using the state feedback signal to determine the current load state of the resonant conversion circuit includes: comparing the resonant current with a set current threshold to obtain the load state.

[0010] The state feedback signal includes the ripple amplitude of the output voltage, and the step of using the state feedback signal to determine the current load state of the resonant conversion circuit includes: comparing the peak value of the ripple amplitude with a set amplitude threshold to obtain the load state.

[0011] Among them, the load state includes a no-load state and a light-load state, and the step of generating a high-frequency switching signal or a low-frequency gap signal based on the load state includes: generating a low-frequency gap signal when the load state is a no-load state or a light-load state; generating a high-frequency switching signal when the load state is not a no-load state or a light-load state.

[0012] In order to solve the above technical problems, another technical solution adopted in the present application is: to provide a switch control circuit, wherein the switch control circuit is used to couple with the resonant conversion circuit; wherein the switch control circuit is used to control the resonant conversion circuit using the switch control method as described in any of the above items.

[0013] In order to solve the above technical problems, another technical solution adopted in the present application is: to provide an electronic device, wherein the electronic device includes a shell and a switch control circuit connected to the shell; wherein the switch control circuit is the switch control circuit as described above.

[0014] The beneficial effect of the present application is as follows: Different from the prior art, the switch control method provided by the present application obtains a state feedback signal in the resonant conversion circuit to determine the current load state of the resonant conversion circuit using the state feedback signal, and generates a high-frequency switch signal and / or a low-frequency gap signal based on the load state, so as to use the high-frequency switch signal or the low-frequency gap signal to adjust the switch state of the resonant conversion circuit and adjust the output voltage of the resonant conversion circuit, so as to reasonably select the high-frequency switch signal or the low-frequency gap signal in response to different load states of the resonant conversion circuit to control it, so as to effectively ensure the efficiency of the resonant conversion circuit when light load and no load, and the stability of its output voltage and DC gain curve state; and through the adaptive selection of the high-frequency switch signal or the low-frequency gap signal, the problem of excessive ripple caused by control delay in the intermittent ripple of the hysteresis control method is effectively avoided, and there is no need to design the hysteresis loop width separately, thereby solving the performance problem of the resonant conversion circuit when working under light load. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work, among which: Figure 1 It is a flowchart of the first implementation method of the switch control method of the present application; Figure 2 It is a structural schematic diagram of the first embodiment of the switch control circuit of the present application; Figure 3 yes Figure 1 A schematic diagram of the process of an embodiment of S12; Figure 4 yes Figure 1 S13 is a schematic diagram of a flow chart of an embodiment; Figure 5 is a structural schematic diagram of a second embodiment of the switch control circuit of the present application; Figure 6 It is a flow chart of the second implementation mode of the switch control method of the present application; Figure 7 is a structural schematic diagram of a third embodiment of the switch control circuit of the present application; Figure 8 It is a structural schematic diagram of an implementation method of a resonant conversion circuit; Fig. 9 yes Figure 7 Schematic diagram of the wave generation of the switch control circuit; Fig.10 It is a schematic structural diagram of an embodiment of an electronic device of the present application. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0017] The terms "first", "second" and "third" in this application are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first", "second" and "third" may explicitly or implicitly include at least one of the features. In the description of this application, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. All directional indications (such as up, down, left, right, front, back...) in the implementation mode of this application are only used to explain the relative position relationship, movement, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication also changes accordingly. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally also includes steps or units that are not listed, or optionally also includes other steps or units inherent to these processes, methods, products or devices.

[0018] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0019] The present application is described in detail below with reference to the accompanying drawings and implementation methods.

[0020] Please refer to Figure 1 and Figure 2 ,in, Figure 1is a flow chart of the first embodiment of the switch control method of the present application, Figure 2 This is a schematic diagram of the structure of the first embodiment of the switch control circuit of the present application. Specifically, it may include the following steps: S11: Obtaining a state feedback signal in the resonant conversion circuit.

[0021] It is understandable that the switch control method in this embodiment is specifically applied to Figure 2 The switch control of the resonant conversion circuit 200 shown in the figure, the first switch control circuit 100 is used to couple with the resonant conversion circuit 200; wherein, the first switch control circuit 100 is used to control the resonant conversion circuit 200 by adopting any switch control method in this article.

[0022] It is worth noting that the resonant conversion circuit 200 may specifically be a half-bridge LLC converter, a full-bridge LLC converter or other forms of LLC circuit topology, which is not limited in this embodiment.

[0023] The first switch control circuit 100 may specifically include a control chip, a DSP (Digital Signal Processing) chip, an MCU (Micro Controller Unit) circuit, a CPU (Central Processing Unit), a single-chip microcomputer, a field programmable gate array, a programmable logic device, a discrete gate or transistor logic device, a discrete hardware, or any other reasonable circuit unit with a signal processing function, and the present application does not limit this.

[0024] In addition, the term "coupled" herein refers to any direct and indirect connection means. Therefore, if the first circuit is described as being coupled to the second circuit, it means that the first circuit can be directly connected to the second circuit through electrical connection or signal connection methods such as wireless transmission, optical transmission, etc., or can be indirectly connected to the second circuit through other circuits or connection means.

[0025] Specifically, the first switch control circuit 100 is used to sample and obtain state feedback signals such as current and voltage reflecting the current working state of the resonant conversion circuit 200 from the resonant conversion circuit 200, such as one or more of any reasonable electrical parameters such as the resonant current on the primary side or the output voltage on the secondary side in an LLC resonant converter, and the present application does not limit this.

[0026] Specifically, the first switch control circuit 100 can be obtained through a current transformer, a voltage divider, a sampling resistor or other types of circuit units, and converted into a digital signal by an ADC (Analog To Digital Converter) for use by the first switch control circuit 100.

[0027] S12: Determine the current load state of the resonant conversion circuit using the state feedback signal.

[0028] The first switch control circuit 100 can determine the current load condition by processing and analyzing the collected state feedback signal. For example, if the output voltage is lower than the expected value, it indicates that the load may be increased; conversely, if the output voltage is higher than expected, it indicates that the load may be reduced. Based on this information, it is also possible to know in real time whether the load is light load, heavy load or no load.

[0029] It is worth noting that the common load states of electronic circuits, also known as load states, usually include: no load, light load, heavy load, full load, overload, over-resonance, and under-resonance. Among them, the no-load state refers to the output end without load connection, and the circuit only maintains its own loss. ‌Extremely light load‌: The load current is close to no load but not completely disconnected, the resonant current amplitude is lower than the critical threshold, and the circuit may enter an intermittent control mode (such as burst mode) to reduce losses. ‌Normal light load‌: The load current is small but still continuously transmits energy, the operating frequency shifts to the under-resonance region, the gain is sensitive to frequency, and dynamic adjustment is required to maintain stable output. ‌Heavy load / full load state: The circuit operates near the resonance point, the resonant cavity current amplitude is the largest, the energy transfer efficiency reaches the peak, the switching frequency is close to the main resonant frequency, the gain is stable and insensitive to load changes. ‌Over-resonance: The switching frequency is higher than the main resonant frequency, and the current phase lag increases, resulting in an increase in the turn-off loss of the switch tube in the LLC resonant converter and a degradation of the zero-current turn-off characteristic of the secondary diode. ‌Sub-resonance: The switching frequency is lower than the main resonant frequency, the current discontinuity phenomenon is obvious, and the conduction loss increases, but it is conducive to achieving wide range voltage regulation.

[0030] S13: Generate a high-frequency switch signal and / or a low-frequency gap signal based on the load state.

[0031] Furthermore, the first switch control circuit 100 will use an appropriate control algorithm to determine whether the switching frequency or duty cycle needs to be adjusted according to different load conditions. For different load conditions, the first switch control circuit 100 will select different control modes. For example, when the load is heavy, the switching frequency is increased to enhance the energy transmission efficiency, that is, a high-frequency switching signal is generated; and under light load or no-load conditions, a lower-frequency gap signal is generated, that is, the power device in the resonant conversion circuit 200 is in a closed state for a period of time, thereby achieving energy saving, that is, a corresponding low-frequency gap signal is generated.

[0032] It is worth noting that the high-frequency switching signal can specifically be one or more of any reasonable control signals such as a PWM (Pulse Width Modulation) signal or a PFM (Pulse Frequency Modulation) signal, so that when the load state of the resonant conversion circuit 200 is not no-load or light-load, for example, when the load state of the resonant conversion circuit 200 is heavy-load or full-load, the high-frequency switching signal can be used to drive and control it, and the present application does not limit this.

[0033] In addition, the low-frequency gap signal can be specifically a Burst signal, which is manifested as a discrete pulse group, that is, a plurality of high-frequency switching pulses are continuously output in a specific time period, and then enter a silent period, forming an intermittent working mode of periodic start and stop. For example, under light load, the LLC converter in Burst mode may continuously output 10 switching cycles at a frequency of 100kHz (kilohertz), and then stop working for 50μs (microseconds) to reduce losses.

[0034] S14: Utilize the high-frequency switching signal or the low-frequency gap signal to adjust the switching state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit.

[0035] The first switch control circuit 100 uses the currently generated high-frequency switch signal or low-frequency gap signal to control the on and off time of the power semiconductor device in the resonant conversion circuit 200, thereby changing the energy transfer characteristics of the resonant network to ensure that the output voltage of the resonant conversion circuit 200 is stable within a set target range regardless of how the load changes. By accurately adjusting the switching frequency and duty cycle, the output voltage fluctuation caused by load changes can be effectively compensated, and the efficiency of the resonant conversion circuit 200 at light load and no load and the stability of its output voltage and DC gain curve state can be guaranteed.

[0036] The above scheme controls the resonant conversion circuit 200 by reasonably selecting a high-frequency switching signal or a low-frequency gap signal in response to different load states of the resonant conversion circuit 200, so as to effectively ensure the efficiency of the resonant conversion circuit 200 when lightly loaded and unloaded, and the stability of its output voltage and DC gain curve state; and through the adaptive selection of the high-frequency switching signal or the low-frequency gap signal, the problem of excessive ripple caused by control delay in the intermittent wave of the hysteresis control method is effectively avoided, and there is no need to design the hysteresis loop width separately, thereby solving the performance problem of the resonant conversion circuit 200 when working under light load.

[0037] Furthermore, in one embodiment, the state feedback signal includes the resonant current, and the above S12 may specifically include: comparing the resonant current with a set current threshold to obtain the load state.

[0038] It is understandable that the load state is determined by monitoring the amplitude change of the resonant current in the resonant conversion circuit 200. When the load is light or unloaded, the resonant current is significantly reduced, and the waveform is distorted (such as parasitic oscillation enhancement), and the current sensor can be used to collect the primary or secondary current signal in real time for threshold comparison, that is, when it is detected that the resonant current is lower than the set current threshold, it is determined that the current load state of the resonant conversion circuit 200 is light; and when the resonant current is not lower than the set current threshold, it is determined that the current load state of the resonant conversion circuit 200 is not light.

[0039] Furthermore, in one embodiment, the state feedback signal includes the ripple amplitude of the output voltage, and the above S12 may specifically include: comparing the peak value of the ripple amplitude with a set amplitude threshold to obtain the load state.

[0040] It is understandable that when the load state of the resonant conversion circuit 200 is light load / no load, the output voltage ripple amplitude will increase, and by detecting the high-frequency fluctuation characteristics of the output voltage (such as the peak-to-peak value of the ripple), its load state can be effectively determined. For example, the voltage sampling circuit and the digital controller are combined to analyze the ripple amplitude in real time to determine whether the peak value of the output voltage ripple amplitude of the resonant conversion circuit 200 is greater than the set amplitude threshold, and when it is detected that the peak value of the ripple amplitude is greater than the set amplitude threshold, it is determined that the current load state of the resonant conversion circuit 200 is light load or no load, and the intermittent control mode is triggered.

[0041] In other embodiments, the first switch control circuit 100 can also monitor the gain characteristic change caused by the operating frequency offset of the resonant conversion circuit 200 when the load is light. By real-time monitoring the ratio of the switching frequency to the resonant frequency or the shape of the gain curve, combined with a preset gain-frequency model, it is determined whether the resonant conversion circuit 200 enters a light-load state; or, by detecting the primary current of the transformer in the resonant conversion circuit 200 and converting it into a reference voltage signal, the duty cycle of the switch control signal is dynamically reduced according to its level change, and the reduction amplitude of the duty cycle is directly related to the load level, thereby realizing indirect detection of light load / no-load, which is not limited in this application.

[0042] Please continue reading Figure 3 , Figure 3 yes Figure 1 In one embodiment, the switch control method of the present application includes not only the above S11-S14, but also some more specific steps. Specifically, the above S12 may also include the following steps: S121: Calculate the switching frequency using the difference between the output voltage and the target output voltage.

[0043] Specifically, the state feedback signal includes an output voltage. The first switch control circuit 100 obtains the current output voltage from the resonant conversion circuit 200 to compare the actual output voltage with the preset target output voltage to obtain the difference between the two, that is, the error signal, and then performs proportional integral control on the difference, that is, inputs the difference into a PI (proportional integral) controller to calculate an ideal switching frequency, that is, the measured switching frequency, through the PI controller. The measured switching frequency is intended to make the output voltage as close to the target output voltage as possible.

[0044] S122: Compare the measured switching frequency with the maximum switching frequency of the resonant conversion circuit to obtain a load state.

[0045] Furthermore, the first switch control circuit 100 compares the measured switching frequency with the maximum switching frequency of the resonant conversion circuit 200. If the measured switching frequency is close to or equal to the maximum switching frequency, this generally means that the resonant conversion circuit 200 is trying to respond to a larger load demand at the highest speed, which may indicate that the resonant conversion circuit 200 is currently in a heavy load state. If the measured switching frequency is much lower than the maximum switching frequency, it may indicate that the load of the resonant conversion circuit 200 is light or close to a no-load state, because in this case, a very high switching frequency is not required to maintain the target output voltage.

[0046] It is understandable that by monitoring the output voltage in real time and comparing it with the target voltage, and using the PI control algorithm to accurately adjust the switching frequency, the system can maintain stable and efficient operation under different load conditions. In addition, by comparing the measured switching frequency with the maximum switching frequency, it can also provide the system with important information about the current load level, which helps to achieve a more refined control strategy and improve overall energy efficiency and performance.

[0047] Please continue reading Figure 4 , Figure 4 yes Figure 1 In one embodiment, the switch control method of the present application includes not only the above S11-S14, but also some more specific steps. Specifically, the above S13 may also include the following steps: S131: When the load state is a no-load state or a light-load state, a low-frequency gap signal is generated.

[0048] Specifically, when the first switch control circuit 100 determines that the current load state of the resonant conversion circuit 200 is a no-load state or a light-load state, it selects to generate a low-frequency gap signal to reduce unnecessary high-frequency switching actions, which can significantly reduce the switching loss of the switching element in the resonant conversion circuit 200; in the case of light load or no-load, the lower frequency operation can improve the overall energy efficiency because fast energy transmission is not required at this time; the period, sealing wave duration and emitting wave duration of the low-frequency gap signal can be adjusted according to the specific load conditions to further optimize the performance. And the efficiency of the resonant conversion circuit 200 under light load and no-load conditions and the stability of its output voltage and DC gain curve state are guaranteed.

[0049] S132: When the load state is not a no-load state or a light-load state, a high-frequency switching signal is generated.

[0050] When the first switch control circuit 100 determines that the current load state of the resonant conversion circuit 200 is neither a no-load state nor a light-load state, it generates a high-frequency switching signal to meet higher energy requirements and maintain a stable output voltage, and switches to a high-frequency switching mode; the high-frequency switching signal allows a faster energy transfer rate, which is particularly important for handling a sudden increase in load; the frequency and duty cycle of the high-frequency switching signal are appropriately adjusted to adapt to different load levels and ensure optimal output performance.

[0051] It is understandable that the method of adaptively selecting control signals based on load status greatly improves the flexibility and efficiency of power electronic systems. It can not only provide optimal performance under different load conditions, but also effectively extend the service life of key components and reduce maintenance costs. This strategy is particularly important for application scenarios that require high efficiency, reliability and response speed. It allows the system to always maintain efficient and stable operation over a wide operating range from extremely low load to full load. It also avoids the problem of excessive ripple caused by control delay in the intermittent generation of the hysteresis control method, and there is no need to design the hysteresis loop width separately, thereby solving the performance problem of the resonant conversion circuit 200 when working under light load.

[0052] Please continue reading Figure 5 , Figure 5 It is a structural schematic diagram of the second embodiment of the switch control circuit of the present application.

[0053] In some embodiments, the second switch control circuit 300 specifically further includes a first signal control subcircuit 301, a second signal control subcircuit 302 and a signal selection subcircuit 303, the first signal control subcircuit 301 is coupled to the resonant conversion circuit 200 and the signal selection subcircuit 303, the second signal control subcircuit 302 is coupled to the resonant conversion circuit 200 and the signal selection subcircuit 303, and the signal selection subcircuit 303 is coupled to the resonant conversion circuit 200.

[0054] Furthermore, the above S13 may also specifically include: the first signal control subcircuit 301 generates a low-frequency gap signal based on the currently acquired load state, or by using the difference between the output voltage and the target output voltage to calculate the switching frequency; the second signal control subcircuit 302 generates a high-frequency switching signal based on the currently acquired load state, or by using the difference between the output voltage and the target output voltage to calculate the switching frequency; the signal selection subcircuit 303 receives the low-frequency gap signal sent by the first signal control subcircuit 301 and the high-frequency switching signal sent by the second signal control subcircuit 302, so as to perform a logical AND operation on the low-frequency gap signal and the high-frequency switching signal to obtain a drive control signal, or selects one of the high-frequency switching signal and the low-frequency gap signal as the drive control signal based on a preset rule, so as to use the drive control signal to adjust the switching state of the resonant conversion circuit 200, thereby adjusting the output voltage of the resonant conversion circuit 200.

[0055] It is worth noting that the signal selection subcircuit 303 obtains the low-frequency gap signal corresponding to the drive control signal by performing a logic AND operation on the low-frequency gap signal and the high-frequency switch signal, which is different from the low-frequency gap signal corresponding to the drive control signal by selecting one of the high-frequency switch signal and the low-frequency gap signal according to a preset rule. The former corresponds to the same level state during the wave transmission period and another level state during the closed period; the latter corresponds to a high-frequency pulse signal during the wave transmission period, that is, the same waveform style as the high-frequency switch signal, and another level state during the closed period.

[0056] See also Figure 6 and Figure 7 ,in, Figure 6 is a flow chart of the second embodiment of the switch control method of the present application, Figure 7 Schematic diagram of the structure of the third embodiment of the switch control circuit of the present application. The switch control method of this embodiment is Figure 1 A flow chart of a detailed implementation of the switch control method in the embodiment of the present invention specifically includes the following steps: S21: Obtaining a state feedback signal in the resonant conversion circuit.

[0057] Among them, S21 and Figure 1 For details, please refer to S11 and its related text descriptions, which will not be repeated here.

[0058] S22: Calculate the switching frequency using the difference between the output voltage in the state feedback signal and the target output voltage.

[0059] It is understandable that the switch control method in this embodiment can be specifically as follows: Figure 7The third switch control circuit 400 shown implements switch control on the resonant conversion circuit 200. The third switch control circuit 400 further includes a signal processing subcircuit 401, a voltage-frequency conversion subcircuit 402, a mode selection subcircuit 403, an AND gate logic subcircuit 404, and a drive control subcircuit 405. The signal processing subcircuit 401 is coupled to the voltage-frequency conversion subcircuit 402 and the mode selection subcircuit 403, and is used to couple with the resonant conversion circuit 200. The voltage-frequency conversion subcircuit 402 is coupled to the mode selection subcircuit 403, the mode selection subcircuit 403 is coupled to the AND gate logic subcircuit 404, the AND gate logic subcircuit 404 is coupled to the drive control subcircuit 405, and the drive control subcircuit 405 is coupled to the resonant conversion circuit 200.

[0060] For easier understanding, please continue to refer to Figure 8 , Figure 8 It is a structural schematic diagram of an implementation method of a resonant conversion circuit.

[0061] In some embodiments, the resonant conversion circuit 200 includes a power switching circuit 201, a resonant circuit 202, a switch freewheeling circuit 205, an isolation transformer 203, a rectifier circuit 204, and a voltage-stabilized output circuit 206; the power switching circuit 201 includes a first switch tube Q1 and a second switch tube Q2; the resonant circuit 202 includes a first resonant capacitor Cr1, a second resonant capacitor Cr2, and a resonant inductor Lr; the switch freewheeling circuit 205 includes a first freewheeling resistor Rc1, a second freewheeling resistor Rc2, a first freewheeling capacitor C1, a second freewheeling capacitor C2, a first diode D1, and a second diode D2; the isolation transformer 203 includes a primary winding RZ0, a first sub-secondary winding RZ1, and a second sub-secondary winding RZ2; the rectifier circuit 204 includes a third diode D3 and a fourth diode D4; the voltage-stabilized output circuit 206 further includes a voltage-stabilizing resistor Ro and a voltage-stabilizing capacitor Co.

[0062] The first end of the first switch tube Q1 is coupled to the first end of the first freewheeling resistor Rc1, the second end of the first diode D1 and the first end of the first resonant capacitor Cr1, and is used to couple the first end of the power supply circuit 501. The second end of the second switch tube Q2 is coupled to the second end of the second freewheeling capacitor C2, the first end of the second diode D2 and the second end of the second resonant capacitor Cr2, and is used to couple the second end of the power supply circuit 501. The second end of the first freewheeling resistor Rc1 is coupled to the first end of the first freewheeling capacitor C1, and the second end of the first freewheeling capacitor C1 is coupled to the first diode D1. The first end, the second end of the first switch tube Q1, the first end of the second switch tube Q2, the first end of the second freewheeling resistor Rc2, the second end of the second diode D2 and the first end of the resonant inductor Lr, the second end of the second freewheeling resistor Rc2 is coupled to the first end of the second freewheeling capacitor C2, the second end of the first resonant capacitor Cr1 is coupled to the first end of the second resonant capacitor Cr2 and the second end of the primary winding RZ0, the second end of the resonant inductor Lr is coupled to the first end of the primary winding RZ0, the third end of the first switch tube Q1 and the third end of the second switch tube Q2 are coupled to the drive control sub-circuit 405.

[0063] The primary winding RZ0 is coupled with the first sub-secondary winding RZ1 and the second sub-secondary winding RZ2, the first end of the third diode D3 is coupled with the first end of the first sub-secondary winding RZ1, the second end of the third diode D3 is coupled with the second end of the fourth diode D4 and the first end of the stabilizing resistor Ro, and is used to couple with the load circuit R, that is, the first end of the load circuit 502, the first end of the fourth diode D4 is coupled with the second end of the second sub-secondary winding RZ2, the second end of the stabilizing resistor Ro is coupled with the first end of the stabilizing capacitor Co, the second end of the stabilizing capacitor Co is coupled with the second end of the first sub-secondary winding RZ1 and the first end of the second sub-secondary winding RZ2, and is used to couple with the second end of the load circuit 502.

[0064] Optionally, the first switch tube Q1 and the second switch tube Q2 may be MOSFET (Metal Oxide Semiconductor Field Effect Transistor), triode, thin film transistor or field effect transistor or any other reasonable switch tube, which is not limited in the present application.

[0065] It is worth noting that, in order to distinguish the two ends of each switch tube except the control end, one of the ends is called the first end and the other end is called the second end. When each switch tube is a triode, the control end, that is, the third end, can be specifically the base, the first end is the collector, and the second end is the emitter; or, the third end can also be specifically the base, the first end is the emitter, and the second end is the collector.

[0066] When the above switching tubes are MOSFETs, thin film transistors or field effect transistors, the third end can be a gate, the first end can be a drain, and the second end can be a source; or, the third end can be a gate, the first end can be a source, and the second end can be a drain.

[0067] When each switch tube is a MOSFET, a thin film transistor or a field effect transistor, it can also be a composite transistor or a single transistor, which is not limited in the present application.

[0068] It is worth noting that, in other embodiments, the resonant conversion circuit 200 can also be a half-bridge LLC converter, a full-bridge LLC converter or any other reasonable form of LLC circuit topology. For example, the power switch circuit 201 can also be a full-bridge switch circuit or an asymmetric half-bridge switch circuit. The rectifier circuit 204 can be a full-bridge rectifier circuit 204 or a half-bridge rectifier circuit 204 composed of various switch tubes, and any other reasonable circuit form for realizing AC to DC conversion. The drive control subcircuit 405 in the third switch control circuit 400 is used to send a high-frequency switching signal PWM or a low-frequency gap signal Burst, that is, a drive control signal Gs, to the power switch circuit 201, and specifically send a pulse width adjustment signal PWMA and a pulse width adjustment signal PWMB to the third end of the first switch tube Q1 and the third end of the second switch tube Q2, respectively, to adjust the switching state of the power switch circuit 201, and then adjust the output voltage Vo of the voltage stabilization output circuit 206. This application does not limit this.

[0069] Specifically, the state feedback signal includes the output voltage Vo. The signal processing subcircuit 401 in the third switch control circuit 400 obtains the current output voltage Vo from the voltage stabilizing output circuit 206 of the resonant conversion circuit 200 to compare the actual output voltage Vo with the preset target output voltage Vref to obtain the difference err between the two, that is, the error signal. Then, using the internal PI controller, the difference err is respectively subjected to proportional-integral adjustment 1 and proportional-integral adjustment 2 to output the control voltage vctrl and the intermittent duty cycle D*, respectively. The control voltage vctrl is converted into the measured switching frequency fsw* by the voltage-frequency conversion subcircuit 402 or the conversion logic inside the DSP chip.

[0070] S23: Determine whether the measured switching frequency is greater than the maximum switching frequency.

[0071] Furthermore, the mode selection subcircuit 403 determines whether the currently acquired measured switching frequency fsw* is greater than the maximum switching frequency.

[0072] If the measured switching frequency fsw* is not greater than the maximum switching frequency, S24 is executed; if the measured switching frequency fsw* is greater than the maximum switching frequency, S27 is executed.

[0073] S24: Generate a high-frequency switching signal and a low-frequency gap signal by using the measured switching frequency, and make the duty cycle of the low-frequency gap signal 1.

[0074] When it is determined that the measured switching frequency fsw* is not greater than the maximum switching frequency, that is, the currently required switching frequency is less than the maximum switching frequency, the mode selection subcircuit 403 generates a high-frequency switching signal PWM and a low-frequency gap signal Burst using the currently acquired measured switching frequency fsw*, and assigns the duty cycle of the low-frequency gap signal Burst, that is, the intermittent duty cycle D*, to 1.

[0075] S25: Performing a logic AND operation on the high-frequency switch signal and the low-frequency gap signal to obtain a drive control signal.

[0076] Please continue reading Fig. 9 , Fig. 9 yes Figure 7 Schematic diagram of the wave generation of the switch control circuit.

[0077] It is understandable that the AND gate logic sub-circuit 404 receives the high-frequency switching signal PWM and the low-frequency gap signal Burst, and performs a logic AND operation on the high-frequency switching signal PWM and the low-frequency gap signal Burst to obtain the driving control signal Gs.

[0078] S26: Using the driving control signal to adjust the switch state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit.

[0079] The drive control subcircuit 405 uses the currently generated drive control signal Gs, that is, the high-frequency switching signal PWM or the low-frequency gap signal Burst, to control the power semiconductor device in the resonant conversion circuit 200, that is, the on and off time of the power switch circuit 201, and then change the energy transfer characteristics of the resonant network to ensure that the output voltage Vo of the voltage-stabilized output circuit 206 is stable within a set target range, regardless of how the load changes. By accurately adjusting the switching frequency and duty cycle, the output voltage Vo fluctuation caused by load changes can be effectively compensated, and the efficiency of the resonant conversion circuit 200 at light load and no load and the stability of the output voltage Vo and DC gain curve state can be guaranteed.

[0080] The driving control signal Gs specifically includes a pulse width adjustment signal PWMA and a pulse width adjustment signal PWMB, which are respectively sent to the first switch tube Q1 and the second switch tube Q2 to adjust the switching state of the power switch circuit 201, and further adjust the output voltage Vo of the voltage stabilizing output circuit 206.

[0081] S27: Generate a high-frequency switching signal using the maximum switching frequency.

[0082] When determining that the measured switching frequency fsw* is greater than the maximum switching frequency, the mode selection subcircuit 403 generates the high-frequency switching signal PWM using the maximum switching frequency.

[0083] S28: Generate and adjust the duty cycle of the low-frequency gap signal using the measured switching frequency.

[0084] The mode selection subcircuit 403 now starts to adjust the duty cycle of the low-frequency interval signal Burst, ie, the intermittent duty cycle D*, such as reducing the proportion of the transmitting time or increasing the proportion of the blocking time, thereby continuing to reduce the gain.

[0085] Furthermore, in one embodiment, the above S28 may specifically include: adjusting the signal period of the low-frequency gap signal Burst by using the measured switching frequency fsw*.

[0086] It is understandable that the control logic of the third switch control circuit 400 can dynamically adjust the period of the low-frequency gap signal Burst according to the measured switching frequency fsw* output by the PI controller, that is, when the load changes (that is, the measured switching frequency fsw* changes), the overall period of the low-frequency gap signal Burst will also change accordingly. If the measured switching frequency fsw* is high, it may indicate that the current load is relatively heavy within the light load range, and the third switch control circuit 400 may shorten the period of the low-frequency gap signal Burst to respond to the load change more quickly.

[0087] Furthermore, in one embodiment, the above S28 may specifically include: adjusting the blocking duration and / or the transmitting duration of the low-frequency gap signal Burst by using the measured switching frequency fsw*.

[0088] It is worth noting that the blocking time (off time) refers to the length of time that the low-frequency gap signal Burst is in the "off" state in each cycle. By increasing the blocking time, the energy transmission time can be reduced, which is suitable for situations where the output power needs to be reduced.

[0089] Burst duration (on time): refers to the length of time that the low-frequency gap signal Burst is in the "on" state in each cycle. Increasing the burst duration can improve energy transmission efficiency and is suitable for high-load demand scenarios.

[0090] According to the measured switching frequency fsw*, the third switch control circuit 400 can adjust these two parameters independently or simultaneously to accurately control the rate and total amount of energy transmission. For example, within the range of light load, if the load demand suddenly increases, the duty cycle of the low-frequency gap signal Burst can be increased by reducing the sealing time and increasing the transmitting time, thereby increasing the output voltage Vo; and vice versa.

[0091] Among them, taking the low-frequency gap signal Burst in a signal cycle as Ton, the blocking time as Toff, and the average value of the output voltage Vo in the maximum switching frequency continuous wave state as Ur as an example, it can be known that the intermittent duty cycle , output voltage .

[0092] This application also provides an electronic device, see Fig.10 , Fig.10 1 is a schematic diagram of the structure of an electronic device according to an embodiment of the present application. In this embodiment, the electronic device 30 includes a housing 31 and a fourth switch control circuit 32 connected to the housing 31 .

[0093] It should be noted that the fourth switch control circuit 32 described in this embodiment is the first switch control circuit 100, the second switch control circuit 300, or the third switch control circuit 400 described in any one of the above embodiments. Figure 1-Figure 9 And the related text content will not be repeated here.

[0094] The beneficial effect of the present application is as follows: Different from the prior art, the switch control method provided by the present application obtains a state feedback signal in the resonant conversion circuit to determine the current load state of the resonant conversion circuit using the state feedback signal, and generates a high-frequency switch signal and / or a low-frequency gap signal based on the load state, so as to use the high-frequency switch signal or the low-frequency gap signal to adjust the switch state of the resonant conversion circuit and adjust the output voltage of the resonant conversion circuit, so as to reasonably select the high-frequency switch signal or the low-frequency gap signal in response to different load states of the resonant conversion circuit to control it, so as to effectively ensure the efficiency of the resonant conversion circuit when light load and no load, and the stability of its output voltage and DC gain curve state; and through the adaptive selection of the high-frequency switch signal or the low-frequency gap signal, the problem of excessive ripple caused by control delay in the intermittent ripple of the hysteresis control method is effectively avoided, and there is no need to design the hysteresis loop width separately, thereby solving the performance problem of the resonant conversion circuit when working under light load.

[0095] The above description is only an implementation method of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly used in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A switch control method, applied to switch control of a resonant conversion circuit, characterized in that: The switch control method comprises: Acquiring a state feedback signal in the resonant conversion circuit; Determining a current load state of the resonant conversion circuit using the state feedback signal; generating a high frequency switch signal and / or a low frequency gap signal based on the load state; The high-frequency switching signal or the low-frequency gap signal is used to adjust the switching state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit.

2. The switch control method according to claim 1, characterized in that: The state feedback signal includes an output voltage, and the step of using the state feedback signal to determine the current load state of the resonant conversion circuit includes: Calculating the switching frequency using the difference between the output voltage and the target output voltage; The load state is obtained by comparing the measured switching frequency with the maximum switching frequency of the resonant conversion circuit.

3. The switch control method according to claim 2, characterized in that: The high-frequency switching signal and the low-frequency gap signal are pulse width modulation signals, and the step of comparing the measured switching frequency with the maximum switching frequency of the resonant conversion circuit to obtain the load state comprises: Determining whether the measured switching frequency is greater than the maximum switching frequency; The step of generating a high-frequency switch signal and / or a low-frequency gap signal based on the load state comprises: If the measured switching frequency is less than or equal to the maximum switching frequency, the high-frequency switching signal and the low-frequency gap signal are generated by using the measured switching frequency, and the duty cycle of the low-frequency gap signal is set to 1; Performing a logic AND operation on the high-frequency switch signal and the low-frequency gap signal to obtain a drive control signal; The step of using the high-frequency switching signal or the low-frequency gap signal to adjust the switching state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit includes: The driving control signal is used to adjust the switch state of the resonant conversion circuit to adjust the output voltage of the resonant conversion circuit.

4. The switch control method according to claim 3, characterized in that: The switch control method further includes: If the measured switching frequency is greater than the maximum switching frequency, generating the high-frequency switching signal using the maximum switching frequency; The duty cycle of the low-frequency gap signal is generated and adjusted using the measured switching frequency.

5. The switch control method according to claim 4, characterized in that: The step of generating and adjusting the duty cycle of the low-frequency gap signal by using the measured switching frequency comprises: Using the measured switching frequency to adjust the signal period of the low-frequency gap signal; Or, the measured switching frequency is used to adjust the sealing duration and / or transmitting duration of the low-frequency gap signal.

6. The switch control method according to claim 1, characterized in that: The state feedback signal includes a resonant current, and the step of using the state feedback signal to determine the current load state of the resonant conversion circuit includes: The resonant current is compared with a set current threshold to obtain the load state.

7. The switch control method according to claim 1, characterized in that: The state feedback signal includes the ripple amplitude of the output voltage, and the step of using the state feedback signal to determine the current load state of the resonant conversion circuit includes: The load state is obtained by comparing the peak value of the ripple amplitude with a set amplitude threshold.

8. The switch control method according to claim 1, characterized in that: The load state includes a no-load state and a light-load state, and the step of generating a high-frequency switch signal or a low-frequency gap signal based on the load state includes: When the load state is the no-load state or the light-load state, generating the low-frequency gap signal; When the load state is not the no-load state or the light-load state, the high-frequency switching signal is generated.

9. A switch control circuit, characterized in that: The switch control circuit is used to couple with the resonant conversion circuit; The switch control circuit controls the resonant conversion circuit using the switch control method according to any one of claims 1 to 8.

10. An electronic device, characterized in that: The electronic device comprises a housing and a switch control circuit connected to the housing; Wherein, the switch control circuit is the switch control circuit as claimed in claim 9.

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