Switch control method, switch control circuit and electronic device

Abstract

The present application discloses a switch control method, a switch control circuit, and an electronic device for switch control of a resonant conversion circuit. 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. Through the above-mentioned manner, the switch control method of the present application can reasonably select a high-frequency switch signal or a low-frequency gap signal in response to different load states of the resonant conversion circuit to control it, thereby effectively ensuring the efficiency of the resonant conversion circuit under light load and no-load conditions, and the stability of its output voltage and DC gain curve state, and avoiding the problem of excessive ripple caused by control delay in the intermittent generation of hysteresis control.

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] Currently, the LLC converter (which includes an additional inductor (L) in series with two other components, the inductor L and the capacitor (C)) is a highly efficient resonant topology widely used in medium- and high-power power supplies due to its soft switching characteristics and wide gain range. However, achieving more optimal adaptive control of the LLC converter remains challenging. In particular, excessively high switching frequencies in the LLC converter's drive control signals can hinder efficiency at light loads and no loads. Furthermore, at light loads, the discharge process of the LLC converter's parasitic capacitance after charging significantly impacts the converter's output, altering the DC gain curve and potentially causing the output voltage to lose control. Summary of the Invention

[0003] The main technical problem solved by this 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, causing its output voltage to be out of control.

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

[0005] The state feedback signal includes an output voltage, and the steps of determining the current load state of the resonant conversion circuit using the state feedback signal include: using the difference between the output voltage and the target output voltage to obtain a measured switching frequency; and comparing the measured switching frequency with the maximum switching frequency of the resonant conversion circuit to obtain the load state.

[0006] The high-frequency switching signal and the low-frequency gap signal are pulse-width modulated 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: determining 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; and 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: using the drive control signal to adjust the switching 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 the 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 this application is: providing 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 described in any of the above items.

[0013] In order to solve the above technical problems, another technical solution adopted in this 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 described above.

[0014] The beneficial effects of the present application are as follows: Different from the prior art, the switching 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 switching signal and / or a low-frequency gap signal based on the load state, so as to use the high-frequency switching signal or the low-frequency gap signal to adjust the switching state of the resonant conversion circuit and adjust the output voltage of the resonant conversion circuit, thereby being able to reasonably select the high-frequency switching 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 under light load and no-load conditions 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 ripple of the hysteresis control method is effectively avoided, and there is no need to additionally design the hysteresis loop width, thereby solving the performance problem of the resonant conversion circuit when operating 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 following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present application. Those skilled in the art can also derive other drawings based on these drawings without inventive efforts, among which:

[0016] Figure 1 This is a flow chart of the first embodiment of the switch control method of the present application;

[0017] Figure 2 This is a schematic structural diagram of a first embodiment of the switch control circuit of the present application;

[0018] Figure 3 yes Figure 1 A schematic diagram of a flow chart of an embodiment of S12;

[0019] Figure 4 yes Figure 1 A schematic diagram of a flow chart of an embodiment of S13;

[0020] Figure 5 This is a schematic structural diagram of a second embodiment of the switch control circuit of the present application;

[0021] Figure 6 This is a flow chart of the second embodiment of the switch control method of the present application;

[0022] Figure 7 This is a schematic structural diagram of a third embodiment of the switch control circuit of the present application;

[0023] Figure 8 It is a structural diagram of an embodiment of a resonant conversion circuit;

[0024] Figure 9 yes Figure 7 Schematic diagram of the wave generation of the switch control circuit;

[0025] Figure 10 It is a structural diagram of an embodiment of the electronic device of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0027] The terms "first," "second," and "third" in this application are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features identified. Therefore, features specified as "first," "second," or "third" may explicitly or implicitly include at least one of such features. In the description of this application, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined. All directional designations (such as up, down, left, right, front, back, etc.) in the embodiments of this application are intended only to illustrate the relative positional relationships and movement of components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional designations will also change accordingly. Furthermore, the terms "including," "having," and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to such process, method, product, or apparatus.

[0028] Reference herein to an "embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it refer to independent or alternative embodiments that are mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0029] The present application is described in detail below with reference to the accompanying drawings and implementation methods.

[0030] Please refer to Figure 1 and Figure 2 ,in, Figure 1 This is 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 can include the following steps:

[0031] S11: Obtaining a state feedback signal in the resonant conversion circuit.

[0032] It is understandable that the switch control method in this embodiment is specifically applied to Figure 2 The switching control of the resonant conversion circuit 200 shown in the figure, the first switching control circuit 100 is used to couple with the resonant conversion circuit 200; wherein, the first switching control circuit 100 is used to control the resonant conversion circuit 200 using any switching control method in this document.

[0033] 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.

[0034] 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, discrete hardware, or any other reasonable circuit unit with a signal processing function, and this application does not limit this.

[0035] Furthermore, the term "coupled" as used herein encompasses both direct and indirect connection methods. Therefore, if a first circuit is described as being coupled to a second circuit, this means that the first circuit may be directly connected to the second circuit via electrical connection, wireless transmission, optical transmission, or other signal connection methods, or may be indirectly connected to the second circuit via other circuits or connection methods.

[0036] 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. This application does not limit this.

[0037] Specifically, the first switch control circuit 100 can obtain the current through a current transformer, a voltage divider, a sampling resistor or other types of circuit units, and convert it into a digital signal through an ADC (Analog To Digital Converter) for use by the first switch control circuit 100.

[0038] S12: Determine the current load state of the resonant conversion circuit using the state feedback signal.

[0039] The first switch control circuit 100 processes and analyzes the collected state feedback signal to determine the current load condition. For example, if the output voltage is lower than expected, this may indicate an increase in load; conversely, if the output voltage is higher than expected, this may indicate a decrease in load. Based on this information, it is also possible to determine in real time whether the load is lightly loaded, heavily loaded, or unloaded.

[0040] It's worth noting that common load states for electronic circuits, also known as load conditions, typically include: no load, light load, heavy load, full load, overload, overresonance, and underresonance. The no-load state refers to when no load is connected to the output, and the circuit only maintains its own losses. Extremely light load: The load current is close to no load but not completely disconnected, the resonant current amplitude is below the critical threshold, and the circuit may enter an intermittent control mode (such as burst mode) to reduce losses. Conventional light load: The load current is small but energy is still continuously transmitted. The operating frequency shifts to the underresonance region, and the gain is frequency-sensitive, requiring dynamic adjustment to maintain stable output. Heavy load / full load: The circuit operates near the resonance point, the resonant cavity current amplitude is maximum, energy transfer efficiency reaches peak, the switching frequency approaches the main resonant frequency, the gain is stable, and it is insensitive to load changes. Overresonance: The switching frequency is higher than the main resonant frequency, and the current phase lag increases, resulting in increased turn-off losses of the switch in the LLC resonant converter and degraded zero-current turn-off characteristics 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.

[0041] S13: Generate a high-frequency switch signal and / or a low-frequency gap signal based on the load state.

[0042] Furthermore, the first switch control circuit 100 uses an appropriate control algorithm to determine whether to adjust the switching frequency or duty cycle based on the load state. For different load conditions, the first switch control circuit 100 selects different control modes. For example, when the load is heavy, the switching frequency is increased to enhance energy transmission efficiency, thereby generating a high-frequency switching signal. Under light or no-load conditions, a lower-frequency gap signal is generated, which turns off the power devices in the resonant converter circuit 200 for a period of time, thereby achieving energy savings. This corresponds to generating a low-frequency gap signal.

[0043] 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. This application does not limit this.

[0044] Furthermore, this low-frequency intermittent signal can be specifically a burst signal, which manifests as a discrete pulse group. This signal continuously outputs multiple high-frequency switching pulses within a specific time period, followed by a silent period, creating an intermittent operating mode with periodic starts and stops. For example, under light load, an LLC converter in burst mode might continuously output 10 switching cycles at a frequency of 100 kHz (kilohertz), followed by a 50 μs (microsecond) pause to reduce losses.

[0045] S14: Utilizing the high-frequency switching signal or the low-frequency gap signal to adjust the switching state of the resonant conversion circuit, so as to adjust the output voltage of the resonant conversion circuit.

[0046] The first switch control circuit 100 uses the currently generated high-frequency switching signal or low-frequency gap signal to control the on- and off-times of the power semiconductor devices in the resonant converter circuit 200, thereby changing the energy transfer characteristics of the resonant network to ensure that the output voltage of the resonant converter circuit 200 remains stable within a set target range regardless of load variations. By precisely adjusting the switching frequency and duty cycle, it effectively compensates for output voltage fluctuations caused by load variations, ensuring the efficiency of the resonant converter circuit 200 under light and no-load conditions, and ensuring the stability of its output voltage and DC gain curves.

[0047] 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, thereby effectively ensuring 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. Moreover, 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 ripple of the hysteresis control method is effectively avoided, and there is no need to separately design the hysteresis loop width, thereby solving the performance problem of the resonant conversion circuit 200 under light load operation.

[0048] Furthermore, in one embodiment, the state feedback signal includes the resonant current, and the above S12 may further specifically include: comparing the resonant current with a set current threshold to obtain the load state.

[0049] It is understood 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 no-load, the resonant current significantly decreases and the waveform is distorted (e.g., parasitic oscillations are enhanced). The current sensor can collect the primary or secondary current signal in real time for threshold comparison. Specifically, when the resonant current is detected to be lower than the set current threshold, the current load state of the resonant conversion circuit 200 is determined to be light. When the resonant current is not lower than the set current threshold, the current load state of the resonant conversion circuit 200 is determined to be not light.

[0050] Furthermore, in one embodiment, the state feedback signal includes the ripple amplitude of the output voltage, and the above S12 may further specifically include: comparing the peak value of the ripple amplitude with a set amplitude threshold to obtain the load state.

[0051] It is understood that when the resonant converter circuit 200 is lightly loaded or unloaded, its output voltage ripple amplitude will increase. By detecting the high-frequency fluctuation characteristics of the output voltage (e.g., the peak-to-peak value of the ripple), its load state can be effectively determined. For example, by combining a voltage sampling circuit with a digital controller, the ripple amplitude can be analyzed in real time to determine whether the peak value of the output voltage ripple amplitude of the resonant converter circuit 200 is greater than a preset amplitude threshold. If the peak value of the ripple amplitude is detected to be greater than the preset amplitude threshold, the resonant converter circuit 200 is determined to be lightly loaded or unloaded, and the intermittent control mode is triggered.

[0052] In other embodiments, the first switch control circuit 100 may further monitor gain characteristic changes caused by operating frequency offsets of the resonant converter circuit 200 under light load conditions. 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 converter circuit 200 has entered a light load state. Alternatively, the first switch control circuit 100 may detect the primary transformer current in the resonant converter circuit 200 and convert it into a reference voltage signal. Based on changes in the voltage level, the duty cycle of the switch control signal is dynamically reduced, with the magnitude of the duty cycle reduction being directly related to the load level, thereby indirectly detecting light load / no load conditions. This is not limited in this application.

[0053] Please continue reading Figure 3 , Figure 3 yes Figure 1 Flowchart of S12 in an embodiment. In one embodiment, the switch control method of the present application includes, in addition to the above S11-S14, further includes some more specific steps. Specifically, the above S12 may further include the following steps:

[0054] S121: Calculate the switching frequency using the difference between the output voltage and the target output voltage.

[0055] Specifically, the state feedback signal includes the output voltage. The first switch control circuit 100 obtains the current output voltage from the resonant converter circuit 200, compares the actual output voltage with a preset target output voltage, and obtains the difference between the two, i.e., an error signal. The difference is then subjected to proportional-integral control. That is, the difference is input into a PI (proportional integral) controller, which calculates an ideal switching frequency, i.e., a measured switching frequency, through the PI controller. The measured switching frequency is intended to make the output voltage as close as possible to the target output voltage.

[0056] S122: Compare the measured switching frequency with the maximum switching frequency of the resonant conversion circuit to obtain a load state.

[0057] Furthermore, the first switching control circuit 100 compares the measured switching frequency with the maximum switching frequency of the resonant converter circuit 200. If the measured switching frequency is close to or equal to the maximum switching frequency, this generally means that the resonant converter circuit 200 is attempting to respond to a large load demand at maximum speed, which may indicate that the resonant converter circuit 200 is currently heavily loaded. On the other hand, if the measured switching frequency is much lower than the maximum switching frequency, this may indicate that the resonant converter circuit 200 is lightly loaded or close to no-load, because in this case, an extremely high switching frequency is not required to maintain the target output voltage.

[0058] It's clear that by monitoring the output voltage in real time and comparing it to the target voltage, and using the PI control algorithm to precisely adjust the switching frequency, the system can maintain stable and efficient operation under varying load conditions. Furthermore, by comparing the measured switching frequency with the maximum switching frequency, the system can be provided with valuable information about the current load level, enabling more refined control strategies and improving overall energy efficiency and performance.

[0059] Please continue reading Figure 4 , Figure 4 yes Figure 1 In one embodiment, the switch control method of the present application includes not only S11 to S14 above, but also some more specific steps. Specifically, S13 above may further include the following steps:

[0060] S131: When the load state is a no-load state or a light-load state, a low-frequency gap signal is generated.

[0061] Specifically, when the first switch control circuit 100 determines that the current load state of the resonant converter circuit 200 is no-load or light-load, it selects to generate a low-frequency gap signal to reduce unnecessary high-frequency switching operations, which can significantly reduce the switching losses of the switching elements in the resonant converter circuit 200. Under light-load or no-load conditions, lower frequency operation can improve overall energy efficiency because rapid energy transmission is not required. The period, blocking duration, and transmission duration of the low-frequency gap signal can be adjusted according to the specific load conditions to further optimize performance. This ensures the efficiency of the resonant converter circuit 200 under light-load and no-load conditions, as well as the stability of its output voltage and DC gain curve.

[0062] S132: When the load state is not a no-load state or a light-load state, generate a high-frequency switching signal.

[0063] 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 sudden increases 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.

[0064] It is understandable that the method of adaptively selecting control signals based on load conditions greatly improves the flexibility and efficiency of power electronics systems. It not only provides optimal performance under varying load conditions, but also effectively extends the service life of key components and reduces maintenance costs. This strategy is particularly important for applications that require high efficiency, reliability, and responsiveness. It enables the system to maintain efficient and stable operation across a wide operating range, from extremely low load to full load. It also avoids the problem of excessive ripple caused by control delays in intermittent ripple generation in hysteresis control methods, and eliminates the need to design a separate hysteresis loop width, thereby resolving the performance issues of the resonant converter circuit 200 under light load operation.

[0065] Please continue reading Figure 5 , Figure 5 It is a structural diagram of the second embodiment of the switch control circuit of the present application.

[0066] In some embodiments, the second switch control circuit 300 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. The signal selection subcircuit 303 is coupled to the resonant conversion circuit 200.

[0067] Furthermore, the above-mentioned S13 can also specifically include: the first signal control subcircuit 301 generates a low-frequency gap signal based on the currently obtained 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 obtained 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.

[0068] 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 logical AND operation on the low-frequency gap signal and the high-frequency switch signal. This differs from the method of selecting one of the high-frequency switch signal and the low-frequency gap signal as the low-frequency gap signal corresponding to the drive control signal according to a preset rule. The former has the same level during the on-state period and a different level during the off-state period; the latter has a high-frequency pulse signal during the on-state period, i.e., a waveform pattern identical to that of the high-frequency switch signal, and a different level during the off-state period.

[0069] See also Figure 6 and Figure 7 ,in, Figure 6 This is a flow chart of the second embodiment of the switch control method of the present application. Figure 7 This is a 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 FIG. 1 specifically includes the following steps:

[0070] S21: Obtaining a state feedback signal in the resonant conversion circuit.

[0071] Among them, S21 and Figure 1 For details, please refer to S11 and its related text descriptions, which will not be repeated here.

[0072] S22: Calculate the switching frequency using the difference between the output voltage in the state feedback signal and the target output voltage.

[0073] It is understandable that the switch control method in this embodiment can be specifically as follows: Figure 7 The third switch control circuit 400 shown implements switch control over 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 configured to couple to 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. The drive control subcircuit 405 is coupled to the resonant conversion circuit 200.

[0074] For easier understanding, please continue to refer to Figure 8 , Figure 8 It is a structural diagram of an embodiment of a resonant conversion circuit.

[0075] 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.

[0076] 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 to 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 to 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 end of 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.

[0077] The primary winding RZ0 is coupled to the first sub-secondary winding RZ1 and the second sub-secondary winding RZ2, the first end of the third diode D3 is coupled to the first end of the first sub-secondary winding RZ1, the second end of the third diode D3 is coupled to the second end of the fourth diode D4 and the first end of the stabilizing resistor Ro, and is used to couple to the load circuit R, that is, the first end of the load circuit 502, the first end of the fourth diode D4 is coupled to the second end of the second sub-secondary winding RZ2, the second end of the stabilizing resistor Ro is coupled to the first end of the stabilizing capacitor Co, the second end of the stabilizing capacitor Co is coupled to 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 to the second end of the load circuit 502.

[0078] Optionally, the first switch tube Q1 and the second switch tube Q2 can be specifically a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a triode, a thin film transistor or a field effect transistor or any other reasonable switch tube, which is not limited in this application.

[0079] It is worth noting that, to distinguish the two ends of each switching transistor other than the control terminal, one of the terminals is referred to as the first terminal and the other as the second terminal. When each switching transistor is a triode, the control terminal, i.e., the third terminal, can be specifically the base, while the first terminal is the collector and the second terminal is the emitter. Alternatively, the third terminal can be specifically the base, while the first terminal is the emitter and the second terminal is the collector.

[0080] 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.

[0081] 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 this application.

[0082] It is worth noting that, in other embodiments, the resonant conversion circuit 200 may specifically be a half-bridge LLC converter, a full-bridge LLC converter, or any other reasonable form of LLC circuit topology. For example, the power switching circuit 201 may specifically be a full-bridge switching circuit or an asymmetric half-bridge switching circuit. The rectifier circuit 204 may specifically be a full-bridge rectifier circuit 204 or a half-bridge rectifier circuit 204 composed of various switching tubes, or any other reasonable circuit form for achieving AC-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, i.e., a drive control signal Gs, to the power switching circuit 201, and specifically to send a pulse width adjustment signal PWMA and a pulse width adjustment signal PWMB to the third terminal of the first switching tube Q1 and the third terminal of the second switching tube Q2, respectively, to adjust the switching state of the power switching circuit 201, and thereby adjust the output voltage Vo of the voltage-regulated output circuit 206. This application does not limit this.

[0083] Specifically, the state feedback signal includes the output voltage Vo. The signal processing sub-circuit 401 in the third switch control circuit 400 obtains the current output voltage Vo from the voltage-stabilized output circuit 206 of the resonant conversion circuit 200, compares the actual output voltage Vo with the preset target output voltage Vref, and obtains the difference err between the two, i.e., 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 sub-circuit 402 or the conversion logic inside the DSP chip.

[0084] S23: Determine whether the measured switching frequency is greater than the maximum switching frequency.

[0085] Furthermore, the mode selection sub-circuit 403 determines whether the currently acquired measured switching frequency fsw* is greater than the maximum switching frequency.

[0086] 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.

[0087] S24: Generate a high-frequency switching signal and a low-frequency gap signal using the measured switching frequency, and set the duty cycle of the low-frequency gap signal to 1.

[0088] When the mode selection sub-circuit 403 determines 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, it uses the currently obtained measured switching frequency fsw* to generate a high-frequency switching signal PWM and a low-frequency gap signal Burst, and assigns the duty cycle of the low-frequency gap signal Burst, that is, the intermittent duty cycle D*, to 1.

[0089] S25: Performing a logic AND operation on the high-frequency switch signal and the low-frequency gap signal to obtain a drive control signal.

[0090] Please continue reading Figure 9 , Figure 9 yes Figure 7 Schematic diagram of the wave generation of the switch control circuit.

[0091] 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.

[0092] S26: Utilizing the driving control signal to adjust the switching state of the resonant conversion circuit, so as to adjust the output voltage of the resonant conversion circuit.

[0093] The drive control subcircuit 405 uses the currently generated drive control signal Gs, namely the high-frequency switching signal PWM or the low-frequency burst signal Burst, to control the on- and off-times of the power semiconductor device in the resonant converter circuit 200, namely the power switch circuit 201. This, in turn, alters the energy transfer characteristics of the resonant network to ensure that the output voltage Vo of the voltage-regulated output circuit 206 remains stable within a set target range, regardless of load variations. By precisely adjusting the switching frequency and duty cycle, it effectively compensates for fluctuations in the output voltage Vo caused by load variations, ensuring the efficiency of the resonant converter circuit 200 under light and no-load conditions, and the stability of its output voltage Vo and DC gain curves.

[0094] Among them, the drive control signal Gs specifically includes a pulse width adjustment signal PWMA and a pulse width adjustment signal PWMB, which are used to be sent to the first switch tube Q1 and the second switch tube Q2 respectively to adjust the switching state of the power switch circuit 201, and further adjust the output voltage Vo of the voltage stabilization output circuit 206.

[0095] S27: Generate a high-frequency switching signal using the maximum switching frequency.

[0096] When determining that the measured switching frequency fsw* is greater than the maximum switching frequency, the mode selection sub-circuit 403 generates the high-frequency switching signal PWM using the maximum switching frequency.

[0097] S28: Generate and adjust the duty cycle of the low-frequency gap signal using the measured switching frequency.

[0098] The mode selection subcircuit 403 now starts to adjust the duty cycle of the low-frequency gap signal Burst, that is, the intermittent duty cycle D*, for example, reducing the proportion of the transmission time or increasing the proportion of the blocking time, thereby continuing to reduce the gain.

[0099] Furthermore, in one embodiment, the above S28 may further specifically include: adjusting the signal period of the low-frequency gap signal Burst by using the measured switching frequency fsw*.

[0100] It is understood that the control logic of the third switch control circuit 400 can dynamically adjust the period of the low-frequency gap signal Burst based on the measured switching frequency fsw* output by the PI controller. That is, when the load changes (i.e., 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 load is relatively heavy within the light load range. In this case, the third switch control circuit 400 may shorten the period of the low-frequency gap signal Burst to more quickly respond to load changes.

[0101] Furthermore, in one embodiment, the above S28 may specifically include: adjusting the blocking duration and / or transmitting duration of the low-frequency gap signal Burst by using the measured switching frequency fsw*.

[0102] It's worth noting that the burst duration (off time) refers to the length of time the low-frequency intermittent signal, Burst, is "off" within each cycle. Increasing the burst duration can reduce energy transmission time, which is suitable for situations where output power needs to be reduced.

[0103] Burst duration (on time): This refers to the length of time the low-frequency intermittent signal (Burst) is in the "on" state within each cycle. Increasing the burst duration improves energy transmission efficiency and is suitable for high-load demand scenarios.

[0104] Based on the measured switching frequency fsw*, the third switch control circuit 400 can independently or simultaneously adjust these two parameters to precisely control the rate and total amount of energy transferred. For example, if the load demand suddenly increases within the light load range, the duty cycle of the low-frequency intermittent signal Burst can be increased by reducing the blocking duration and increasing the transmitting duration, thereby increasing the output voltage Vo. The reverse is also true.

[0105] Among them, taking the low-frequency gap signal Burst in a signal cycle as the wave duration Ton, the wave blocking duration 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 seen that the intermittent duty cycle , output voltage .

[0106] This application also provides an electronic device, see Figure 10 , Figure 10 FIG. 3 is a schematic diagram of the structure of an electronic device according to an embodiment of the present invention. In this embodiment, the electronic device 30 includes a housing 31 and a fourth switch control circuit 32 connected to the housing 31 .

[0107] 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. Figures 1-9 And the related text content will not be repeated here.

[0108] The beneficial effects of the present application are as follows: Different from the prior art, the switching 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 switching signal and / or a low-frequency gap signal based on the load state, so as to use the high-frequency switching signal or the low-frequency gap signal to adjust the switching state of the resonant conversion circuit and adjust the output voltage of the resonant conversion circuit, thereby being able to reasonably select the high-frequency switching 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 under light load and no-load conditions 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 ripple of the hysteresis control method is effectively avoided, and there is no need to additionally design the hysteresis loop width, thereby solving the performance problem of the resonant conversion circuit when operating under light load.

[0109] 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 description and drawings of this application, or directly or indirectly applied 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 converter circuit, characterized in that: The switch control method includes: Acquiring a state feedback signal in the resonant conversion circuit; wherein the state feedback signal includes an output voltage; Calculating the switching frequency using the difference between the output voltage and the target output voltage; Determining whether the measured switching frequency is greater than the maximum switching frequency of the resonant conversion circuit; If the measured switching frequency is less than or equal to the maximum switching frequency, generating a high-frequency switching signal and a low-frequency gap signal using the measured switching frequency, and setting the duty cycle of the low-frequency gap signal 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 driving control 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, wherein: 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.

3. The switch control method according to claim 2, wherein: The step of generating and adjusting the duty cycle of the low-frequency gap signal by using the measured switching frequency includes: adjusting the signal period of the low-frequency gap signal using the measured switching frequency; Alternatively, the measured switching frequency is used to adjust the blocking duration and / or transmitting duration of the low-frequency gap signal.

4. 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 3.

5. An electronic device, characterized in that: The electronic device includes 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 4.

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