Control method, control device, integrated circuit control chip and switching power supply

Abstract

The invention discloses a control method, a control device, an integrated circuit control chip and a switching power supply, and the method comprises the steps: level shift: receiving a sampling voltage signal representing the size and change trend of a whole-period resonance current in a resonant cavity of a resonant converter, the sampling voltage signal is boosted into a first voltage signal which is all positive voltage, and a direct-current bias voltage signal is generated at the same time; a charge signal generation step of generating a charge signal representing the power transmission quantity of the resonant converter according to the first voltage signal and the DC bias voltage signal, the charge signal including a slope compensation component with a set proportion; and a feedback control step of controlling the switching circuit according to the charge signal and the feedback voltage signal to realize energy conversion. According to the invention, the design difficulty and design cost of the integrated circuit control chip can be reduced, and the applicability of the integrated circuit control chip can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of switching converters, and in particular to a control method, a control device, an integrated circuit control chip, and a switching power supply. Background Art

[0002] Compared to traditional switching converters, LLC resonant converters are favored by industry experts due to their high efficiency, soft switching, and ability to achieve higher power density. However, traditional methods for controlling LLC resonant converters typically use frequency control based on single voltage loop feedback, which suffers from drawbacks such as poor transient response. With technological advancements, the requirements for the transient response of LLC resonant converters are becoming increasingly stringent. The industry has proposed a charge control scheme that combines input charge with output power to achieve dual-loop control. This scheme significantly improves the transient response of the resonant converter while simplifying loop compensation design and improving practicality.

[0003] For LLC resonant converters, the input charge can typically be obtained through either resonant capacitor voltage sampling or resonant current integration. For resonant capacitor voltage sampling, the sampling circuit design is complex when used in a full-bridge LLC resonant converter, increasing design difficulty and cost. In a half-bridge LLC resonant converter, due to the presence of a DC offset of 1 / 2VIN in the resonant capacitor voltage, real-time input voltage sampling is required to calibrate the resonant capacitor voltage sampling center value, which also increases design difficulty. The requirement for two sampling values increases the risk of control accuracy being affected by sampling value interference. For resonant current integration, the sampling circuit is relatively simple for both half-bridge and full-bridge LLC resonant converters. For example, in a half-bridge LLC resonant converter, resonant current sampling can be performed using a small capacitor shunt plus a resistor. In a full-bridge LLC resonant converter, resonant current sampling can be performed using a mutual inductor. However, due to the operating characteristics of the LLC resonant converter, its resonant current can be both positive and negative, and the corresponding resonant current sampling voltage is a voltage value with a reference ground that can vary. For integrated circuit control chips, handling negative voltages is difficult and costly, making it difficult to implement.

[0004] In order to weaken or avoid the impact of negative voltage, the existing technology has also revealed some solutions. For example, the invention patent "Current mode control for resonant converter circuits" with publication number US8085559B1 proposes a "unilateral single-shot" charge control method, that is, only the positive half-cycle resonant current is integrated, and the negative half-cycle drive pulse width directly copies the positive half-cycle drive pulse width. This solution can greatly weaken the impact of the negative voltage signal of the negative current sampling in the negative half-cycle. However, since only the positive half-cycle charge control is introduced, the resonant converter is at risk of failure and its reliability is reduced during transient conditions such as startup or short circuit. Another solution is the solution proposed in the invention patent "Charging Mode Control Device for Resonant Converter" with publication number CN102130593B, which is to add a full-wave rectifier circuit after sampling the full-cycle resonant current. Although this can completely avoid the influence of negative voltage, in actual application, due to the conduction voltage drop of the diode or switch tube in the full-wave rectifier circuit, the resonant current sampling signal has crossover distortion, resulting in a decrease in control accuracy and failure to meet application requirements. Summary of the Invention

[0005] In view of this, the technical problem to be solved by the present invention is to propose a control method, a control device, an integrated circuit control chip and a switching power supply, which at least to a certain extent solve one of the technical problems existing in the prior art.

[0006] The inventive concept of the present application is as follows: without increasing the complexity of the resonant current sampling circuit, the resonant current sampling signal is converted into a fully positive voltage signal by level shifting, thereby reducing the difficulty and cost of designing the integrated circuit control chip; at the same time, a charge extraction processing circuit is added to flexibly adjust the slope compensation amount, thereby improving the applicability of the integrated circuit control chip while ensuring stable control.

[0007] As a first aspect of the present invention, the technical solution of the control method provided is as follows:

[0008] A control method for controlling a resonant converter, the resonant converter comprising a resonant cavity circuit, a switching circuit, and an output feedback circuit, the output feedback circuit being configured to obtain a feedback voltage signal representing an output voltage or an output current of the resonant converter, wherein the control method comprises:

[0009] a level shifting step of receiving a sampled voltage signal representing the magnitude and change trend of the entire cycle resonant current in the resonant cavity of the resonant converter, raising the sampled voltage signal to a first voltage signal having a fully positive voltage, and generating a DC bias voltage signal;

[0010] a charge signal generating step of generating a charge signal representing the power transmission amount of the resonant converter based on the first voltage signal and the DC bias voltage signal, wherein the charge signal includes a slope compensation component with a set proportion;

[0011] A feedback control step is performed to control the switch circuit according to the charge signal and the feedback voltage signal to achieve energy conversion.

[0012] Preferably, the charge signal generating step includes:

[0013] a charge integration processing step of converting the first voltage signal and the DC bias voltage signal into an integrated current, and charging an integrating capacitor with the integrated current to generate a charge signal containing a slope compensation component;

[0014] The power-pumping processing step receives the DC bias voltage and generates a power-pumping current according to a first set ratio to discharge the integrating capacitor, so that the proportion of the slope compensation component in the charge signal is the set proportion.

[0015] Furthermore, the amplitude of the DC bias voltage signal is equal to the average value of the first voltage signal.

[0016] Preferably, the first set ratio is 0.1-1.

[0017] Furthermore, the feedback control step includes:

[0018] a comparing step of comparing the charge signal and the feedback voltage signal to generate a reset signal;

[0019] The drive control step generates a complementary drive signal according to the reset signal to control the switch circuit to generate a periodic square wave voltage to achieve periodic energy conversion of the resonant cavity circuit, specifically:

[0020] At the beginning of each half-operating cycle of the resonant converter, the reset signal is released to control the periodic square wave voltage to switch between a low voltage corresponding to the reference ground and a high voltage corresponding to the input voltage. At the same time, the charge signal is controlled to gradually rise from a set fixed level until the charge signal is greater than the feedback voltage signal. The reset signal is valid and maintained for a period of time, and the corresponding half-operating cycle ends and enters the next half-operating cycle.

[0021] Furthermore, when the reset signal is valid, the charge signal is clamped at the set fixed level.

[0022] As a second aspect of the present invention, the technical solution of the embodiment of the control device provided is as follows:

[0023] A control device for controlling a resonant converter, the resonant converter comprising a resonant cavity circuit, a switching circuit, and an output feedback circuit, the output feedback circuit being configured to obtain a feedback voltage signal representing an output voltage or an output current of the resonant converter, wherein the control device comprises:

[0024] a level shift circuit for receiving a sampled voltage signal representing the magnitude and change trend of the entire cycle resonant current in the resonant cavity of the resonant converter, raising the sampled voltage signal to a first voltage signal having a fully positive voltage, and generating a DC bias voltage signal;

[0025] a charge signal generating circuit, configured to generate a charge signal representing an amount of power transferred by the resonant converter based on the first voltage signal and the DC bias voltage signal, wherein the charge signal includes a slope compensation component having a set proportion;

[0026] A feedback control circuit is used to control the switch circuit according to the charge signal and the feedback voltage signal to achieve energy conversion.

[0027] Preferably, the charge signal generating circuit includes:

[0028] a charge integration processing circuit, configured to convert the first voltage signal and the DC bias voltage signal into an integrated current, and charge an integrating capacitor with the integrated current to generate a charge signal containing a slope compensation component;

[0029] The power-pumping processing circuit is configured to receive the DC bias voltage and generate a power-pumping current according to a first set ratio to discharge the integrating capacitor, so that the proportion of the slope compensation component in the charge signal is the set proportion.

[0030] As a third aspect of the present invention, the embodiment and technical solution of the integrated circuit control chip provided are as follows:

[0031] An integrated circuit control chip integrates the circuits in the control device described in the second aspect.

[0032] As a fourth aspect of the present invention, the technical solution of the embodiment of the switching power supply provided is as follows:

[0033] A switching power supply includes a resonant converter, wherein the resonant converter includes:

[0034] Switching circuit;

[0035] A transformer comprising a primary winding and at least one secondary winding;

[0036] A resonant capacitor and a resonant inductor are connected in series with the primary winding to form a resonant cavity circuit;

[0037] A resonant current sampling circuit, coupled to the resonant cavity circuit, to generate a sampling voltage signal representing the magnitude and change trend of the resonant current in the resonant cavity circuit over a full cycle;

[0038] an output feedback circuit connected to the output terminal of the resonant converter to obtain a feedback voltage signal representing the output voltage or output current of the resonant converter;

[0039] Wherein: the switching power supply further includes the control device described in the second aspect or the integrated circuit control chip described in the third aspect, which is used to control the switching circuit to achieve energy conversion.

[0040] Preferably, the switching circuit comprises at least one half-bridge.

[0041] Based on the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) Without increasing the complexity of the resonant current sampling circuit, the original positive and negative resonant current sampling signal can be raised to a fully positive voltage signal through level shifting processing, while not affecting the sampling signal accuracy, which can effectively reduce the design difficulty and design cost of the integrated circuit control chip;

[0043] (2) After level shifting, a DC component is added to the integral current that charges the integral capacitor, which is equivalent to slope compensation. Therefore, there is no need to add an additional ramp circuit, and stable and reliable control can be guaranteed;

[0044] (3) By adding a pumping circuit to discharge the integral capacitor, the DC component in the integral current can be flexibly adjusted, that is, the proportion of the slope compensation amount can be adjusted, which can effectively improve the applicability of the integrated circuit control chip while ensuring stable control;

[0045] (4) Charge integration processing is performed on the entire cycle resonant current signal, which can effectively improve the reliability of transient processes such as startup and short circuit, and is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a circuit diagram of a resonant converter with a control circuit according to an embodiment of the present invention;

[0047] Figure 2 for Figure 1 A specific schematic diagram of the control circuit;

[0048] Figure 3 FIG. 4 is a typical operation timing diagram of a resonant converter using the control circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0050] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this application.

[0051] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate to describe the embodiments of the present application here. 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 necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0052] It should be understood that in the specification, claims and drawings, when a step is described as being connected to another step, the step may be directly connected to the other step, or be connected to the other step through a third step; when an element / unit is described as being "connected" to another element / unit, the element / unit may be "directly connected" to the other element / unit, or be "connected" to the other element / unit through a third element / unit.

[0053] In addition, the figures of this disclosure are merely schematic diagrams of the present disclosure and are not necessarily drawn to scale. Identical reference numbers in the figures denote identical or similar parts, and therefore repeated descriptions thereof will be omitted. Some of the blocks shown in the figures are functional entities that do not necessarily correspond to physically or logically separate entities. These functional entities may be implemented using software, in one or more hardware modules or integrated circuits, or in different networks and / or processor devices and / or microcontrollers.

[0054] As analyzed in the background technology, to realize LLC charge-type control, it is necessary to sample the resonant current signal and perform integration processing. However, the resonant current signal is both positive and negative, and the internal circuit of the chip is difficult to process negative voltage signals. By performing "level shifting" processing on the resonant current sampling signal in the LLC main control chip, the sampling signal can be converted into a positive voltage, but a DC bias is introduced. The DC bias is equivalent to slope compensation. In order to ensure the adjustable range of the signal, the DC bias needs to be large, resulting in a large slope compensation, which will affect the charge control effect, deteriorate the dynamic response, and be unfavorable for the realization of Burst, OPP (over-power protection) and other controls. Based on the level shifting processing, the present invention adds a "charge extraction" processing in the integration processing link, which can offset the DC bias and realize adjustable slope compensation. On the one hand, it improves the stability of the switching power supply while ensuring dynamic response. On the other hand, it is more conducive to using the feedback voltage to reflect power transmission changes and reliably realize Burst, OPP and other controls.

[0055] like Figure 1 FIG. 1 is a circuit diagram of a resonant converter with a control circuit according to an embodiment of the present invention, which can be applied to a switching power supply. Each functional circuit of the control circuit is configured to execute the corresponding steps of the aforementioned control method. Each functional circuit of the control circuit is consistent with the corresponding functional circuit in the aforementioned control device. These functional circuits can be integrated into an integrated circuit control chip.

[0056] In specific implementation, Figure 1 The circuit diagram and its structure are as follows:

[0057] The resonant converter 1 includes a switching circuit 10. The switching circuit 10 is composed of two switching tubes connected in series to form a half-bridge structure, wherein the drain of the first switching tube S1 is connected to the input power supply VIN, the source of the first switching tube S1 is connected to the drain of the second switching tube S2, and the source of the second switching tube S2 is connected to the reference ground GND. The switching circuit 10 is controlled by the control circuit 11 to generate a periodic square wave voltage to drive the LLC resonant circuit 12 to achieve energy conversion. The LLC resonant circuit 12 (also called a resonant cavity circuit) includes a resonant inductor L connected in series in series. r and the primary equivalent excitation inductance L of transformer 13 m , resonant capacitor C r , resonant inductor L r The other end is connected to the source of the first switch tube S1, and the resonant capacitor C r The other end is connected to the reference ground GND. The two secondary windings of the transformer 13 are respectively connected to the drains of the first synchronous rectifier SR1 and the second synchronous rectifier SR2 on the secondary side to form a full-wave rectifier circuit. The sources of the first synchronous rectifier SR1 and the second synchronous rectifier SR2 on the secondary side are connected to the output filter capacitor C in parallel. o And the output resistance Ro One end of the output filter capacitor C o And the output resistance R o The other end is connected to the center tap of the two secondary windings of transformer 13 and serves as the output voltage terminal VOUT of resonant converter 1. A resonant current sampling circuit 14 is coupled to the series loop of LLC resonant circuit 12 and is used to sample the resonant current and output a sampled voltage signal VIr_samp representing the magnitude and change trend of the resonant current over a full cycle. An output feedback circuit 15 is connected to the output of resonant converter 1 and is used to sample the output voltage and output a feedback voltage signal VFB representing the magnitude of the output voltage. The control circuit 11 has a first input terminal that receives the sampled voltage signal VIr_samp representing the magnitude and change trend of the resonant current over a full cycle, a second input terminal that receives the feedback voltage signal VFB representing the magnitude of the output voltage, and an output terminal that is connected to the switching circuit 10. Based on the feedback voltage signal VFB and a charge signal representing the magnitude of the input charge and containing a slope compensation component, the control circuit 11 controls the switching circuit 10 to generate a periodic square wave voltage to drive the LLC resonant circuit 12.

[0058] The control circuit 11 includes a level shift circuit 101, which is configured to receive a sampled voltage signal VIr_samp representing the magnitude and variation trend of the resonant current over a full cycle, and raise the sampled voltage signal VIr_samp by a set ratio while maintaining the AC variation trend unchanged, thereby generating a fully positive first voltage signal VIr and a corresponding DC bias voltage VA, wherein the amplitude of the DC bias voltage VA is equal to the average value of the first voltage signal VIr. A charge integration circuit 102 receives the first voltage signal VIr and the DC bias voltage VA and converts them into a corresponding integrated current. The integrated current includes an AC component representing the magnitude of the resonant current and a DC component introduced by the DC bias voltage VA. The integrated current charges an integrating capacitor during each half-operation cycle, thereby generating a charge signal VCS representing the magnitude of the input charge in the LLC resonant circuit 12. The DC component charging the integrating capacitor is equivalent to a slope compensation component. Therefore, the charge signal VCS already includes the slope compensation component, eliminating the need for an additional slope compensation circuit and simplifying the design of the control circuit. For a resonant converter, in order to take into account both transient performance and control stability, the slope compensation component ratio is generally more appropriately 30% to 60% of the charge signal VCS. The slope compensation component ratio can be adjusted by the power-pumping processing circuit 103. Specifically, after receiving the DC bias voltage VA, the power-pumping processing circuit 103 generates a power-pumping current IDC according to a set ratio. While the integral current charges the integral capacitor, the power-pumping current IDC discharges the integral capacitor, thereby adjusting the slope compensation component ratio to meet the needs of various applications.

[0059] The control circuit 11 further includes a comparison circuit 104. Comparison circuit 104 controls the drive control circuit 105 to generate complementary drive signals GH and GL by comparing the charge signal VCS with the feedback voltage signal VFB. Drive signals GH and GL respectively control the on / off switching of the first switch S1 and the second switch S2, generating a periodic square wave voltage to drive the LLC resonant circuit 12, thereby achieving energy conversion. The amplitude of the periodic square wave voltage switches between a low voltage corresponding to the reference ground and a high voltage corresponding to the input voltage.

[0060] It should be noted that, in practical applications, there is a dead time between the driving signals GH and GL. During the dead time, both the first switch S1 and the second switch S2 are in the off state.

[0061] The level shift circuit 101, charge integration processing circuit 102, power extraction processing circuit 103, comparison circuit 104 and drive control circuit 105 are integrated into the same integrated circuit control chip. The first input pin of the integrated circuit control chip is used to receive the sampled voltage signal VIr_samp, and the second input pin is used to receive the feedback voltage signal VFB.

[0062] For those skilled in the art, Figure 1 The resonant converter shown also includes but is not limited to the following variations:

[0063] (1) Replace the primary switching circuit with a full-bridge structure consisting of two sets of half-bridge switch arms connected in parallel;

[0064] (2) Replace the secondary side rectifier circuit with a bridge rectifier structure consisting of four switching tubes or diodes;

[0065] (3) The output feedback circuit is connected to the output end of the resonant converter, and is used to sample the output current and output a feedback voltage signal VFB representing the magnitude of the output current, thereby achieving output constant current control.

[0066] like Figure 2 As shown, Figure 1 A specific schematic diagram of the control circuit 11. The level shift circuit 101 includes resistors R1, R2, R3, R4, and a reference voltage VREF. The reference voltage VREF is generated by other circuits inside the control circuit 11. Since it is not the innovation of the present invention, it is not shown in the figure. One end of the resistor R1 and the resistor R3 is connected to the reference voltage VREF, the other end of the resistor R1 is connected to one end of the resistor R2, and outputs the first voltage signal VIr, the other end of the resistor R2 is used to receive the sampled voltage signal VIr_samp; and the other end of the resistor R3 is connected to one end of the resistor R4, and outputs a DC bias voltage VA, and the other end of the resistor R4 is connected to the reference ground. According to the resistor voltage divider relationship, there is:

[0067]

[0068] The resistance values of the resistors in the above relationships are directly represented by the reference numerals of the resistors, where R1 = R3 and R2 = R4, to ensure that the DC bias voltage VA is equal to the average value of the first voltage signal VIr, that is,

[0069]

[0070] Where VIr_max is the maximum voltage of the first voltage signal VIr, and VIr_min is the minimum voltage of the first voltage signal VIr. The level shift circuit 101 converts the sampled voltage signal VIr_samp into the first voltage signal VIr and a DC bias voltage VA in real time and continuously, and outputs them to the input of the charge integration circuit 102. The charge integration circuit 102 includes a voltage-to-current circuit 21, switches K1, K2, K3, an integrating capacitor C1, and a NOR gate 22. The first and second input terminals of the voltage-to-current circuit 21 receive a first voltage signal VIr and a DC bias voltage VA, respectively, and convert them into corresponding integrated currents. The first output terminal of the voltage-to-current circuit 21 is connected to one terminal of a switch K1, and the second output terminal of the voltage-to-current circuit 21 is connected to one terminal of a switch K2. The other terminals of switches K1 and K2 are connected to one terminal of an integrating capacitor C1, and serve as the output terminal of the charge integration processing circuit 102 to output a charge signal VCS. The other terminal of the integrating capacitor C1 is connected to a reference ground. Switch K3 is connected in parallel with the integrating capacitor C1 and is used to reset the charge signal VCS on the integrating capacitor C1. Switch K1 is controlled by a drive signal GH, switch K2 is controlled by a drive signal GL, and switch K3 is controlled by a narrow pulse reset signal Rst generated by the dead time between the drive signals GH and GL. The power-drawing processing circuit 103 includes a proportional regulator 31 and a transconductance amplifier 32. The input of the proportional regulator 31 receives a DC bias voltage VA, which is used to scale the DC bias voltage VA and output the scaled voltage signal VA*ks to the non-inverting input of the transconductance amplifier 32. The inverting input of the transconductance amplifier 32 is connected to the reference ground. The pumping current IDC output by the transconductance amplifier 32 is connected to the integrating capacitor C1 to form a discharge loop, which is used to adjust the proportion of the slope compensation component in the charge signal on the integrating capacitor C1. In practical applications, the scaling ratio ks of the DC bias voltage can be flexibly configured to adjust the proportion of the slope compensation component in the charge signal VCS. Preferably, ks can be configured to be 0.1 to 1.

[0071] The following is combined with Figure 3 The typical operation timing diagram of the resonant converter using the control circuit of the embodiment of the present invention is shown to introduce the working principle in detail:

[0072] During the time period from t0 to t1, the reset signal Rst is at a high level, the switch K3 is turned on, and the charge signal VCS is clamped at a zero voltage corresponding to the reference ground. At this time, the drive signals GH and GL are both at a low level, and the switches K1 and K2 are both in the off state.

[0073] At time t1, the reset signal Rst flips to a low level, the drive signal GH flips to a high level, and the drive signal GL remains at a low level, that is, the switch K1 is turned on, and the switches K2 and K3 are in the off state. The voltage-to-current circuit 21 receives the first voltage signal VIr and the DC bias voltage VA and converts them into an integral current I1 to charge the integral capacitor C1, causing the charge signal VCS to rise from zero voltage. At the same time, the power extraction processing circuit 103 receives the DC bias voltage VA and converts it into a discharge current IDC to discharge the integral capacitor C1, thereby adjusting the DC bias in the integral current I1 from y1 to y2, where y2 ≥ 0, while keeping the AC quantity x unchanged. According to the capacitor charging formula i = C*dv / dt, we have:

[0074]

[0075] where v x (t) is the AC component, representing the input charge, v y2 (t) is the DC component, which represents the slope compensation amount. Preferably, by adjusting ks to make v y2 (t) accounts for 30% to 60% of vcs(t).

[0076] At time t2, the charge signal VCS rises to a level greater than the feedback voltage VFB. The comparator circuit 104 outputs a reset signal to cause the drive control circuit 105 to control the drive signal GH to reset to a low level. The switch K1 is turned off. At the same time, the reset signal Rst flips to a high level, controlling the switch K3 to turn on, resetting the charge signal VCS. At this point, the resonant converter completes half a cycle of energy conversion.

[0077] During the time period from t2 to t3, the reset signal Rst maintains a high level, the switch K3 is turned on, and the charge signal VCS is clamped at a zero voltage corresponding to the reference ground. At this time, the drive signals GH and GL are both low levels, and the switches K1 and K2 are both in the off state.

[0078] At time t3, the reset signal Rst flips to a low level, the drive signal GL flips to a high level, and the drive signal GH remains at a low level, that is, the switch K2 is turned on, and the switches K1 and K3 are in the off state. The voltage-to-current circuit 21 receives the first voltage signal VIr and the DC bias voltage VA and converts them into an integral current I2 to charge the integral capacitor C1, so that the charge signal VCS starts to rise from zero voltage. At the same time, the power extraction processing circuit 103 receives the DC bias voltage VA and converts it into a discharge current IDC to discharge the integral capacitor C1, thereby adjusting the DC bias amount in the integral current I2 from y1 to y2, where y2 ≥ 0, while keeping the AC quantity x unchanged.

[0079] It should be noted that if the input / output power remains unchanged, the total integrated current ICh used to charge the integrating capacitor C1 in each half cycle should remain unchanged.

[0080] At time t4, the charge signal VCS rises to a level greater than the feedback voltage VFB. The comparator circuit 104 outputs a reset signal to cause the drive control circuit 105 to control the drive signal GL to reset to a low level, turning off the switch K2. Simultaneously, the reset signal Rst flips to a high level, turning on the control switch K3 and resetting the charge signal VCS. At this point, the resonant converter completes another half-cycle of energy conversion.

[0081] From time t0 to t4, the resonant converter completes a control cycle and then repeats the above control process.

[0082] As can be seen from the description of the above embodiments, the control method, control device, integrated circuit control chip, and switching power supply provided by the present invention utilize level shifting and power extraction to achieve stable and reliable charge control of the resonant converter without the need to process negative voltage signals, significantly reducing the design difficulty and cost of the integrated circuit control chip. Furthermore, the slope compensation component ratio in the power extraction circuit can be flexibly configured according to actual application circumstances, effectively broadening the applicability of the integrated circuit control chip.

[0083] It should be noted that the embodiments described above are merely illustrative of the technical solutions and contents of the present invention, and should not be construed as limiting the present invention. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention. However, these improvements and modifications do not deviate from the spirit of the present invention or exceed the scope defined by the appended claims, and should be considered within the scope of protection of the present invention.

Claims

1. A control method for controlling a resonant converter, wherein the resonant converter comprises a resonant cavity circuit, a switching circuit, and an output feedback circuit, wherein the output feedback circuit is used to obtain a feedback voltage signal representing the output voltage or output current of the resonant converter, wherein: The control method includes: a level shifting step of receiving a sampled voltage signal representing the magnitude and change trend of the entire cycle resonant current in the resonant cavity of the resonant converter, raising the sampled voltage signal to a first voltage signal having a fully positive voltage, and generating a DC bias voltage signal; a charge signal generating step of generating a charge signal representing the power transmission amount of the resonant converter based on the first voltage signal and the DC bias voltage signal, wherein the charge signal includes a slope compensation component with a set proportion; A feedback control step is performed to control the switch circuit according to the charge signal and the feedback voltage signal to achieve energy conversion.

2. The control method according to claim 1, characterized in that: The charge signal includes a slope compensation component with a set ratio by the following steps: a charge integration processing step of converting the first voltage signal and the DC bias voltage signal into an integrated current, and charging an integrating capacitor with the integrated current to generate a charge signal containing a slope compensation component; The power-pumping processing step receives the DC bias voltage and generates a power-pumping current according to a first set ratio to discharge the integrating capacitor, so that the proportion of the slope compensation component in the charge signal is the set proportion.

3. The control method according to claim 1, characterized in that: The amplitude of the DC bias voltage signal is equal to the average value of the first voltage signal.

4. The control method according to claim 1, characterized in that: The first set ratio is 0.1-1.

5. The control method according to claim 1, characterized in that: The feedback control step comprises: a comparing step of comparing the charge signal and the feedback voltage signal to generate a reset signal; The drive control step generates a complementary drive signal according to the reset signal to control the switch circuit to generate a periodic square wave voltage to achieve periodic energy conversion of the resonant cavity circuit, specifically: At the beginning of each half-operating cycle of the resonant converter, the reset signal is released to control the periodic square wave voltage to switch between a low voltage corresponding to the reference ground and a high voltage corresponding to the input voltage. At the same time, the charge signal is controlled to gradually rise from a set fixed level until the charge signal is greater than the feedback voltage signal. The reset signal is valid and maintained for a period of time, and the corresponding half-operating cycle ends and enters the next half-operating cycle.

6. The control method according to claim 5, characterized in that: When the reset signal is valid, the charge signal is clamped at the set fixed level.

7. A control device for controlling a resonant converter, the resonant converter comprising a resonant cavity circuit, a switching circuit, and an output feedback circuit, the output feedback circuit being configured to obtain a feedback voltage signal representing an output voltage or an output current of the resonant converter, wherein: The control device comprises: a level shift circuit for receiving a sampled voltage signal representing the magnitude and change trend of the entire cycle resonant current in the resonant cavity of the resonant converter, raising the sampled voltage signal to a first voltage signal having a fully positive voltage, and generating a DC bias voltage signal; a charge signal generating circuit, configured to generate a charge signal representing an amount of power transferred by the resonant converter based on the first voltage signal and the DC bias voltage signal, wherein the charge signal includes a slope compensation component having a set proportion; A feedback control circuit is used to control the switch circuit according to the charge signal and the feedback voltage signal to achieve energy conversion.

8. The control device according to claim 7, characterized in that: The charge signal generating circuit comprises: a charge integration processing circuit, configured to convert the first voltage signal and the DC bias voltage signal into an integrated current, and charge an integrating capacitor with the integrated current to generate a charge signal containing a slope compensation component; The power-pumping processing circuit is configured to receive the DC bias voltage and generate a power-pumping current according to a first set ratio to discharge the integrating capacitor, so that the proportion of the slope compensation component in the charge signal is the set proportion.

9. An integrated circuit control chip, characterized in that: The circuits in the control device according to claim 7 or 8 are integrated therein.

10. A switching power supply comprising a resonant converter, the resonant converter comprising: Switching circuit; A transformer comprising a primary winding and at least one secondary winding; A resonant capacitor and a resonant inductor are connected in series with the primary winding to form a resonant cavity circuit; A resonant current sampling circuit, coupled to the resonant cavity circuit, to generate a sampling voltage signal representing the magnitude and change trend of the resonant current in the resonant cavity circuit over a full cycle; an output feedback circuit connected to the output terminal of the resonant converter to obtain a feedback voltage signal representing the output voltage or output current of the resonant converter; It is characterized in that: the switching power supply also includes the control device according to claim 7 or 8, or the integrated circuit control chip according to claim 9, which is used to control the switching circuit to achieve energy conversion.

11. The switching power supply according to claim 10, characterized in that: The switching circuit includes at least one half-bridge.

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