Soft start control circuit and method, resonant conversion control circuit, and electronic equipment

Abstract

The present application discloses a soft start control circuit and method, a resonant conversion control circuit, and an electronic device. The soft start control circuit includes: a charge feedback circuit that obtains a charge feedback signal by using a resonant output signal; a voltage feedback circuit that obtains a voltage feedback signal by using the difference between a power supply output signal and a target reference voltage; a logic control circuit that generates a first control signal in a first startup stage; generates a second control signal with a maximum preset switching frequency and an adjustable dead time in a second startup stage; in a third startup stage, performs ramp compensation on the voltage feedback signal to obtain a feedback adjustment signal, and generates a third control signal by using the feedback adjustment signal and the charge feedback signal; and the logic control circuit adjusts an inverter AC signal by using the first to third control signals. By the above method, the soft start control circuit of the present application has a relatively fast dynamic response speed, a small startup current, and a simple control logic.

Description

Technical Field

[0001] The present application relates to the technical field of power supplies, and in particular, to a soft-start control circuit and method, a resonant conversion control circuit, and an electronic device. Background Art

[0002] Currently, resonant converters have been widely used in the field of high-frequency switching power supplies due to their unique switching characteristics, which can achieve low switching losses, high conversion efficiency, and high power density. The LLC resonant converter, which includes an additional inductor (L, inductance) in series with two other components, an inductor L and a capacitor (C, capacitor), is named the L-L-C converter. As a relatively classic topology in resonant converters, its control method generally adopts a single voltage loop control, that is, a direct frequency control method or an average current control method. The common problems of these two methods are low system bandwidth, poor dynamic response, and large output ripple.

[0003] Based on this, the new generation of LLC resonant converters adopts a charge control mode, by sampling the charge information of the resonant cavity as the inner-loop control quantity. However, because the charge mode controls the LLC switching frequency indirectly, compared with the direct frequency control mode, the frequency of each cycle of the charge control LLC is unknown. Therefore, its soft-start strategy is more complex than the direct frequency control, and there are still problems such as a large starting current and poor linearity of the output voltage. Summary of the Invention

[0004] The main technical problem to be solved by the present application is to provide a soft-start control circuit and method, a resonant conversion control circuit, and an electronic device, which can solve the problems of poor dynamic response, large output ripple, large starting current, and poor linearity of the output voltage existing in the control method of the existing LLC resonant converter.

[0005] To solve the above technical problems, a technical solution adopted in this application is: to provide a soft start control circuit, which is applied to the start-up control of a resonant conversion circuit. The resonant conversion circuit includes an inverter circuit, a resonant circuit, and a power conversion circuit. The resonant circuit is coupled to the inverter circuit and the power conversion circuit, and the power conversion circuit is used to be coupled to a load circuit. Among them, the soft start control circuit includes: a charge feedback circuit, which is used to be coupled to the resonant circuit to obtain a resonant output signal in the resonant circuit, and use the resonant output signal to obtain a charge feedback signal; a voltage feedback circuit, which is used to be coupled to the power conversion circuit to obtain a power output signal output by the power conversion circuit to the load circuit, and use the difference between the power output signal and a target reference voltage to obtain a voltage feedback signal; a logic control circuit, which is coupled to the charge feedback circuit and the voltage feedback circuit, and is used to be coupled to the inverter circuit; among them, the logic control circuit is configured to: in the first start-up stage, generate a first control signal according to a preset rule; in the second start-up stage, receive the charge feedback signal sent by the charge feedback circuit and the voltage feedback signal sent by the voltage feedback circuit, and generate a second control signal by using a maximum preset switching frequency and an adjustable dead time; among them, the adjustable dead time is positively correlated with the difference; in the third start-up stage, perform ramp compensation on the voltage feedback signal by using a preset ramp compensation slope to obtain a feedback adjustment signal, and use the feedback adjustment signal and the charge feedback signal to generate a third control signal; the logic control circuit is also used to sequentially send the first control signal, the second control signal, and the third control signal to the inverter circuit, so that the inverter circuit sequentially uses the first control signal, the second control signal, and the third control signal to adjust the inverter AC signal output to the resonant circuit.

[0006] Among them, the logic control circuit is configured to: after a preset power-on duration, enter the second start-up stage from the first start-up stage; when the power output signal or the voltage feedback signal is greater than or equal to the product of the average value of the charge feedback signal and a mode switching control coefficient, enter the third start-up stage from the second start-up stage.

[0007] Among them, the charge feedback circuit includes a current sampling sub-circuit, an integration sub-circuit, and a voltage bias sub-circuit. The current sampling sub-circuit is coupled to the resonant circuit and the integration sub-circuit, and the integration sub-circuit and the voltage bias sub-circuit are coupled to the logic control circuit; among them, the current sampling sub-circuit is used to sample and obtain a resonant current signal in the resonant output signal; the integration sub-circuit is used to receive the resonant current signal sent by the current sampling sub-circuit, and integrate and adjust the resonant current signal into a phase modulation voltage signal; the logic control circuit is used to receive the phase modulation voltage signal sent by the integration sub-circuit and a preset bias voltage output by the voltage bias sub-circuit, and superimpose the preset bias voltage on the phase modulation voltage signal to obtain a charge feedback signal.

[0008] Among them, the preset bias voltage is greater than or equal to half of the difference between the peak and valley of the phase modulation voltage signal.

[0009] Among them, the charge feedback circuit includes a voltage sampling sub-circuit, and the voltage sampling sub-circuit is coupled to the resonant circuit and the logic control circuit to sample and obtain the resonant capacitor voltage in the resonant circuit; the logic control circuit is used to receive the resonant capacitor voltage sent by the voltage sampling sub-circuit to obtain a charge feedback signal by using the resonant capacitor voltage.

[0010] Among them, the inverter circuit includes a first switch sub-circuit and a second switch sub-circuit. The first switch sub-circuit is coupled to the second switch sub-circuit, the resonant circuit, and the logic control circuit, and the second switch sub-circuit is coupled to the logic control circuit; among them, the third control signal includes a first drive signal and a second drive signal, and the logic control circuit is configured to: in the third startup stage, in the first half cycle of each signal period of the third control signal, when the second drive signal is adjusted from the first level to the second level, delay a set duration or simultaneously perform ramp compensation on the voltage feedback signal by using a preset ramp compensation slope to obtain a feedback adjustment signal; and delay the set duration to adjust the first drive signal from the second level to the first level; when the voltage amplitudes of the feedback adjustment signal and the charge feedback signal are equal, adjust the first drive signal from the first level to the second level; in the second half cycle of each signal period, copy the first drive signal of each first half cycle to obtain the second drive signal; the logic control circuit is further used to send the first drive signal and the second drive signal to the first switch sub-circuit and the second switch sub-circuit respectively, so that the first switch sub-circuit and the second switch sub-circuit change their switch states respectively under the action of the first drive signal and the second drive signal to adjust the inverter AC signal.

[0011] Among them, the adjustable dead time is the sum of the product of the difference value and the dead time adjustment coefficient and the preset minimum dead time.

[0012] To solve the above technical problems, another technical solution adopted in this application is: to provide a soft start control method applied to the start-up control of a resonant conversion circuit. The soft start control method includes: obtaining a resonant output signal and a power supply output signal; obtaining a charge feedback signal using the resonant output signal; obtaining a voltage feedback signal using the power supply output signal; generating a first control signal using a preset rule; adjusting an inverter AC signal using the first control signal; after a preset power-on duration, detecting whether the power supply output signal or the voltage feedback signal is less than the product of the average value of the charge feedback signal and a mode switching control coefficient; if the power supply output signal or the voltage feedback signal is less than the product, generating a second control signal using a maximum preset switching frequency and an adjustable dead time; wherein, the adjustable dead time is positively correlated with the voltage feedback signal; adjusting the inverter AC signal using the second control signal; if the power supply output signal or the voltage feedback signal is greater than or equal to the product, performing ramp compensation on the voltage feedback signal using a preset ramp compensation slope to obtain a feedback adjustment signal; generating a third control signal using the feedback adjustment signal and the charge feedback signal; adjusting the inverter AC signal using the third control signal.

[0013] Among them, the step of obtaining a charge feedback signal using the resonant output signal includes: obtaining a resonant current signal in the resonant output signal; integrating the resonant output signal to obtain a phase-modulated voltage signal; superimposing a preset bias voltage on the phase-modulated voltage signal to obtain a charge feedback signal.

[0014] Among them, the step of obtaining a charge feedback signal using the resonant output signal includes: obtaining a resonant capacitor voltage in the resonant output signal; obtaining a charge feedback signal using the resonant capacitor voltage.

[0015] Among them, the third control signal includes a first drive signal and a second drive signal. The step of performing ramp compensation on the voltage feedback signal using a preset ramp compensation slope to obtain a feedback adjustment signal includes: in the first half cycle of each signal period of the third control signal, when the second drive signal is adjusted from a first level to a second level, delaying a preset duration or simultaneously performing ramp compensation on the voltage feedback signal using a preset ramp compensation slope to obtain a feedback adjustment signal; the step of generating a third control signal using the feedback adjustment signal and the charge feedback signal includes: delaying a preset duration to adjust the first drive signal from the second level to the first level; when the voltage amplitudes of the feedback adjustment signal and the charge feedback signal are equal, adjusting the first drive signal from the first level to the second level; in the second half cycle of each signal period, copying the first drive signal of each first half cycle to obtain a second drive signal; the step of adjusting the inverter AC signal using the third control signal includes: adjusting the inverter AC signal using the first drive signal and the second drive signal.

[0016] To solve the above technical problems, another technical solution adopted by this application is: to provide a resonant conversion control circuit, wherein the resonant conversion control circuit includes a resonant conversion circuit and a soft start control circuit. The resonant conversion circuit includes an inverter circuit, a resonant circuit, and a power conversion circuit. The resonant circuit is coupled to the inverter circuit and the power conversion circuit. The power conversion circuit is used to be coupled to a load circuit. The soft start control circuit is coupled to the inverter circuit, the resonant circuit, and the power conversion circuit; wherein, the soft start control circuit is the soft start control circuit described in any one of the above.

[0017] To solve the above technical problems, another technical solution adopted by this application is: to provide an electronic device, wherein the electronic device includes a housing and a power supply circuit connected to the housing; wherein, the power supply circuit is the soft start control circuit described in any one of the above, or the resonant conversion control circuit described above.

[0018] The beneficial effects of the present application are as follows: Different from the prior art, the charge feedback circuit in the soft start control circuit provided by the present application is used to obtain the resonant output signal in the resonant circuit, so as to obtain a charge feedback signal by using the resonant output signal; the voltage feedback circuit obtains the power supply output signal output by the power conversion circuit to the load circuit, so as to obtain a voltage feedback signal by using the difference between the power supply output signal and the target reference voltage; the logic control circuit is configured to: in the first startup stage, generate a first control signal according to a preset rule; in the second startup stage, receive the charge feedback signal sent by the charge feedback circuit and the voltage feedback signal sent by the voltage feedback circuit, and generate a second control signal by using the maximum preset switching frequency and adjustable dead time; wherein, the adjustable dead time is positively correlated with the difference; in the third startup stage, perform ramp compensation on the voltage feedback signal by using a preset ramp compensation slope to obtain a feedback adjustment signal, so as to generate a third control signal by using the feedback adjustment signal and the charge feedback signal; the logic control circuit is further configured to sequentially send the first control signal, the second control signal, and the third control signal to the inverter circuit, so that the inverter circuit sequentially uses the first control signal, the second control signal, and the third control signal to adjust the inverter AC signal output to the resonant circuit, thereby being able to suppress the instantaneous impact current in a timely manner by adopting different control strategies in different startup stages at the initial stage when the soft start control circuit starts to operate, that is, at the initial stage of power-on startup, so as to avoid losses to the circuit; by implementing control at the maximum preset switching frequency in the second startup stage and adjusting the duty cycle in response to the difference between the power supply output signal and the target reference voltage, the dynamic response speed is faster and the starting resonant cavity current is smaller; and in the third startup stage, control is achieved by comparing the output values of the charge feedback loop and the voltage feedback loop, the input power can be quickly and accurately controlled according to the output load, and the dynamic response speed of the loop is further improved. The control logic is relatively simple, better bandwidth and dynamic performance can be achieved, and at the same time, the resonant cavity current can be accurately controlled, so that the linearity of the output voltage of the resonant conversion circuit for realizing control is also better. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings, where:

[0020] Figure 1 is a schematic structural diagram of the first embodiment of the soft start control circuit of the present application;

[0021] Figure 2 is Figure 1 a waveform schematic diagram of an embodiment of the voltage feedback signal in the voltage feedback circuit in

[0022] Figure 3 is Figure 1 A waveform schematic diagram of an embodiment of the charge feedback signal in the charge feedback circuit;

[0023] Figure 4 is Figure 1 A waveform schematic diagram of the third control signal sent by the soft start control circuit in the third start-up stage;

[0024] Figure 5 A schematic structural diagram of the second embodiment of the soft start control circuit of the present application;

[0025] Figure 6 A schematic structural diagram of the third embodiment of the soft start control circuit of the present application;

[0026] Figure 7 A schematic structural diagram of the fourth embodiment of the soft start control circuit of the present application;

[0027] Figure 8 A schematic flow diagram of the first embodiment of the power supply start-up control method of the present application;

[0028] Figure 9 is Figure 8 A schematic flow diagram of an embodiment of S52;

[0029] Figure 10 is Figure 8 A schematic flow diagram of another embodiment of S52;

[0030] Figure 11 A schematic flow diagram of the second embodiment of the power supply start-up control method of the present application;

[0031] Figure 12 A schematic structural diagram of an embodiment of the resonant conversion control circuit of the present application;

[0032] Figure 13 A schematic structural diagram of an embodiment of the electronic device of the present application. Specific Embodiments

[0033] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the scope of protection of the present application.

[0034] The terms "first", "second", and "third" in this application are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", and "third" may explicitly or implicitly include at least one of such features. In the description of this application, the meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. All directional indications (such as up, down, left, right, front, back...) in the embodiments of this application are only used to explain the relative positional relationship, movement conditions, etc. between components in a specific posture (as shown in the drawings). If the specific posture changes, then the directional indications will also change accordingly. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0035] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0036] The following provides a detailed description of this application in conjunction with the drawings and embodiments.

[0037] Please refer to Figure 1 , Figure 1 which is a schematic structural diagram of the first embodiment of the soft start control circuit of this application. In this embodiment, the soft start control circuit 10 includes: a charge feedback circuit 11, a voltage feedback circuit 12, and a logic control circuit 13.

[0038] Among them, a soft start control circuit 10 provided in this application is specifically applied to the start-up control of a resonant conversion circuit 100, and the resonant conversion circuit 100 is used in the power supply of an electrical load. After using an externally provided power input signal and performing corresponding adjustment and control on the power input signal to obtain a power output signal Vo, it is provided to the electrical load in any reasonable electronic device such as a server, a computer, an intelligent communication device, etc. for operation. This embodiment does not limit this.

[0039] Specifically, the resonant conversion circuit 100 further includes an inverter circuit 101, a resonant circuit 102, and a power conversion circuit 103. The resonant circuit 102 is coupled to the inverter circuit 101 and the power conversion circuit 103, and the power conversion circuit 103 is used to be coupled to the load circuit 201.

[0040] The inverter circuit 101 is used to receive a power input signal and, by using the internal switching operation mechanism thereof, such as the on-off operation mechanism of switching devices such as IGBT (Insulated Gate Bipolar Transistor), high-frequency transistors, MOSFET (Metal Oxide Semiconductor Field Effect Transistor), and triodes, quickly switches direct current or alternating current under signal control to generate an alternating voltage waveform and obtain an inverted AC signal.

[0041] It should be noted that the power input signal can be specifically understood as the power supply input provided by an external DC power supply or an AC power supply, or can also be understood as the secondary power supply output obtained by performing power conversion and regulation on the mains power frequency power supply, photovoltaic power supply, independent generator, or any other reasonable superior AC or DC power supply.

[0042] In addition, "coupled" in this article refers to including any direct and indirect connection means. Therefore, if it is described in the article that the first circuit is coupled to the second circuit, it means that the first circuit can be directly connected to the second circuit through electrical connection or signal connection means such as wireless transmission and optical transmission, or can be indirectly electrically connected or signal-connected to the second circuit through other circuits or connection means.

[0043] The resonant circuit 102 is directly connected to the inverter circuit 101 to receive the inverted AC signal sent by the inverter circuit 101, and performs one or more of any reasonable signal regulations such as filtering and shaping, phase shift equalization on the inverted AC signal to obtain a resonant output signal, in order to achieve better output characteristics and ensure that subsequent links, such as the power conversion circuit 103 or the load, obtain more stable and efficient electrical energy.

[0044] The power conversion circuit 103 is coupled to the resonant circuit 102 to receive the resonant output signal sent by the resonant circuit 102, and performs power conversion and regulation control on the resonant output signal to obtain a stable power output, that is, the power output signal Vo, and then outputs it to the load circuit 201 to meet the electrical energy usage of the load circuit 201.

[0045] Among them, the load circuit 201 can be understood as a signal function circuit that operates by using the power output signal Vo of the power conversion circuit 103.

[0046] Specifically, the charge feedback circuit 11 is used to be coupled to the resonant circuit 102, and is used to sample and obtain a resonant output signal from the resonant circuit 102, so as to perform one or more of any reasonable signal processing such as voltage regulation, filtering, integral transformation, phase modulation, and voltage biasing based on the resonant output signal, and obtain a charge feedback signal Vcr that can reflect the current charge information of the resonant circuit 102 in real time.

[0047] The voltage feedback circuit 12 is used to be coupled to the power conversion circuit 103, and is used to sample and obtain a power output signal Vo output by the power conversion circuit 103 to the load circuit 201, so as to subtract the currently obtained power output signal Vo from the target reference voltage Vref to obtain a difference Verr therebetween, and further based on the difference Verr, adopt a voltage loop or speed loop control strategy, or a PI (proportional integral) controller to obtain a specific output signal for signal regulation, that is, a voltage feedback signal Vc.

[0048] It should be noted that the target reference voltage Vref can be specifically understood as a reference voltage that changes in the whole starting stage, where the power output signal Vo monotonically linearly increases from 0 to the target output voltage Vobj in a theoretical state and stabilizes at the target output voltage Vobj.

[0049] The logic control circuit 13 is coupled to the charge feedback circuit 11 and the voltage feedback circuit 12, and is used to be coupled to the inverter circuit 101.

[0050] Among them, the logic control circuit 13 is configured to: in the first starting stage, generate a first control signal according to a preset rule based on a preset program.

[0051] Please continue to refer to Figure 2 , Figure 2 is Figure 1 a waveform schematic diagram of an embodiment of the voltage feedback signal in the voltage feedback circuit in

[0052] It should be noted that the first starting stage and the second starting stage and the third starting stage mentioned in this article can be specifically understood as the initial stage when the soft start control circuit 10 starts up from power-on, or from obtaining the resonant output signal in the resonant circuit 102, or from obtaining the power output signal Vo output by the power conversion circuit 103 to the load circuit 201, until the power output signal Vo output by the power conversion circuit 103 to the load circuit 201 stabilizes at the target output voltage Vobj, or the voltage feedback signal Vc stabilizes at a preset regulation control value, and different starting stages are further obtained by dividing the initial stage based on the set rules according to time sequence.

[0053] For convenience of quantization, specifically, it can be based on the operation duration of the soft start control circuit 10 when powered on and starting up, and / or, the entire process of the power output signal Vo output by the power conversion circuit 103 to the load circuit 201 rising from 0V (volt) to the target output voltage Vobj and stabilizing at the target output voltage Vobj is divided into time intervals; and / or, the time interval of the voltage feedback signal Vc rising from 0V to the preset adjustment control value is divided to obtain the first startup stage, the second startup stage, and the third startup stage.

[0054] In some embodiments, the first startup stage can specifically be based on a set duration, that is, starting from the moment when the soft start control circuit 10 is powered on and starting up, the time stage of T0 - T1 running for the set duration is the first startup stage, or it can also be determined according to the T0 - T1 time stage when the output voltage of the power output signal Vo rises from 0V to the preset voltage value. The present application does not limit this.

[0055] Among them, in the initial stage when the resonant conversion circuit 100 receives the input of the power input signal, it is usually necessary to charge the bootstrap capacitor of the high - side switch tube of the inverter circuit 101, and the charging time needs to ensure that the bootstrap voltage is sufficient. Therefore, the set duration can specifically be determined by the soft start control circuit 10 to satisfy that the bootstrap voltage is sufficient and leave a reasonable margin. The present application does not limit this.

[0056] In addition, the preset rule can be to generate the first control signal by adopting a preset duty cycle, a preset signal frequency, or by adopting a preset number of continuous pulses and stopping sending pulses at other times, etc. Specifically, it is set and adjusted according to the actual control scenario of the soft start control circuit 10 to ensure that the bootstrap voltage is sufficient. The present application does not limit this.

[0057] Furthermore, in the second startup stage, the logic control circuit 13 is further configured to receive the charge feedback signal Vcr sent by the charge feedback circuit 11 and the voltage feedback signal Vc sent by the voltage feedback circuit 12 to generate a second control signal corresponding to the maximum preset switching frequency fmax and the adjustable dead - time Td of the resonant circuit 102.

[0058] In addition, the dead - time refers to the time introduced to avoid the two switch tubes connected in a push - pull manner from conducting simultaneously, and it is an interlock delay time set to avoid bridge arm through - connection, so as to ensure that the switch tube turns on again after turning off, and avoid short - circuit problems caused by asymmetric on - and - off times.

[0059] In some embodiments, the adjustable dead time Td is specifically positively correlated with the difference Verr between the power supply output signal Vo and the target reference voltage Vref. That is, when the difference Verr increases, the adjustable dead time Td also correspondingly increases, so that the duty cycle of the second control signal decreases correspondingly, so as to have a larger resonant output signal at the initial stage of starting up. The corresponding power supply output signal Vo is also larger, and when the difference Verr from the target reference voltage Vref is larger, the resonant output signal can be reduced as quickly as possible to effectively achieve soft start-up.

[0060] Please continue to refer to Figure 3 and Figure 4 , where Figure 3 is Figure 1 a schematic waveform diagram of a charge feedback signal in a charge feedback circuit in Figure 4 is Figure 1 a schematic waveform diagram of the third control signal sent by the soft start control circuit in the third start-up stage.

[0061] Specifically, in the third start-up stage, the logic control circuit 13 performs ramp compensation on the voltage feedback signal Vc by using a preset ramp compensation slope to obtain a feedback adjustment signal Vcomp, and then compares the feedback adjustment signal Vcomp with the charge feedback signal Vcr to generate a third control signal of the charge feedback signal Vcr based on the difference between the two.

[0062] It should be noted that the ramp compensation is a control technique used to improve the stability of the system and reduce the steady-state error. By superimposing a ramp signal with a controllable slope on the set voltage signal, the dynamic response characteristics of the system can be changed. Among them, the preset ramp compensation slope refers to the slope parameter used for ramp compensation. This slope can be adjusted according to the requirements of the system to achieve the optimal compensation effect.

[0063] Furthermore, the logic control circuit 13 is also used to sequentially send the first control signal, the second control signal, and the third control signal to the inverter circuit 101, so that the inverter circuit 101 changes its switching state successively under the action of the first control signal, the second control signal, and the third control signal, and then adjusts the operation of the resonant circuit 102 to adjust the inverter AC signal output by the inverter circuit 101 to the resonant circuit 102, so as to suppress the instantaneous large current in the initial stage as much as possible.

[0064] In some embodiments, the first control signal, the second control signal, and the third control signal may specifically be one or more of any reasonable control signals such as PWM (Pulse Width Modulation) signals or PFM (Pulse Frequency Modulation) signals. The present application does not limit this.

[0065] In some embodiments, the logic control circuit 13 may specifically include one of any reasonable circuit units with signal processing functions, such as a control chip, an MCU (MicroController Unit) circuit, a CPU (Central Processing Unit), a single-chip microcomputer, a field-programmable gate array, a programmable logic device, discrete gates, or transistor logic devices, discrete hardware, etc. The present application does not limit this.

[0066] In the above solution, in the initial stage when the soft start control circuit 10 starts to operate, that is, in the initial stage of power-on startup, different control strategies are adopted in different startup stages to timely suppress the instantaneous impact current to avoid losses to the circuit; in the second startup stage, control is achieved with the maximum preset switching frequency fmax, and the duty cycle is adjusted in response to the difference Verr between the power supply output signal Vo and the target reference voltage Vref, so that the dynamic response speed is faster and the startup resonant cavity current is smaller; and in the third startup stage, control is achieved by comparing the output values of the charge feedback loop and the voltage feedback loop, which can quickly and accurately control the input power according to the output load, further improving the loop dynamic response speed. The control logic is relatively simple, enabling better bandwidth and dynamic performance. At the same time, it can accurately control the resonant cavity current, resulting in better linearity of the output voltage of the resonant conversion circuit 100 that realizes the control.

[0067] In one embodiment, the logic control circuit 13 is specifically configured to: after a preset power-on duration, that is, enter the second startup stage from the first startup stage according to the time setting, so as to change from adopting the control strategy corresponding to the first startup stage to adopting the control strategy corresponding to the second startup stage to implement corresponding startup control for the resonant conversion circuit 100, that is, change from adjusting the inverter AC signal using the first control signal to adjusting the inverter AC signal using the second control signal.

[0068] Further, the logic control circuit 13 is further configured to enter the third starting stage from the second starting stage when it is determined that the current power output signal Vo or voltage feedback signal Vc is greater than or equal to the product of the average value of the charge feedback signal Vcr and the mode switching control coefficient k1, so as to change from the control strategy corresponding to the second starting stage to the control strategy corresponding to the third starting stage to implement corresponding starting control on the resonant conversion circuit 100, that is, to change from regulating the inverter AC signal using the second control signal to regulating the inverter AC signal using the third control signal.

[0069] It can be understood that the first starting stage, the second starting stage, and the third starting stage are specifically interval divisions according to time sequence, and each time interval is continuous.

[0070] Among them, the first starting stage is specifically obtained by dividing according to time setting. For example, the power-on starting is used as the starting moment T0, and the working operation set duration T1 is used as the ending moment.

[0071] Moreover, the ending moment T1 of the first starting stage also corresponds to the starting moment of the second starting stage. The judgment condition for the ending moment of the second starting stage is whether the logic control circuit 13 determines that the current power output signal Vo or voltage feedback signal Vc is less than the product of the average value of the charge feedback signal Vcr and the mode switching control coefficient k1, and the moment when the power output signal Vo or voltage feedback signal Vc is equal to the product is used as the ending moment T2 of the second starting stage, and at the same time, it is also the starting moment of the third starting stage.

[0072] It can be seen from this that the first starting stage specifically corresponds to the time stage of T0 - T1, the second starting stage corresponds to the time stage of T1 - T2, and the third starting stage corresponds to the time stage of T2 and later.

[0073] It is worth noting that in the initial stage of power-on starting of the resonant conversion circuit 100, the power output signal Vo and the voltage feedback signal Vc have the characteristics of similar monotonically linear increase and stabilizing at a certain constant value, but the slopes of the corresponding monotonically linear increases are different. The mode switching control coefficient k1 corresponding to using the comparison between the power output signal Vo and the product as the judgment condition for the ending moment of the second starting stage is different from the mode switching control coefficient k1 corresponding to using the comparison between the voltage feedback signal Vc and the product as the judgment condition for the ending moment of the second starting stage, which is specifically determined by the actual control scenario, and this application does not limit this.

[0074] In one embodiment, in the second startup stage, when the logic control circuit 13 generates the second control signal by using the maximum preset switching frequency fmax and the adjustable dead time Td, specifically, the difference Verr between the power supply output signal Vo and the target reference voltage Vref is used to adjust the adjustable dead time Td.

[0075] Wherein, the adjustable dead time Td can specifically be the sum of the product of the difference Verr and the dead time adjustment coefficient k2 and the preset minimum dead time Td-min, that is, the adjustable dead time Td = Td-min + k2 * Verr; and the dead time adjustment coefficient k2 is a positive value.

[0076] In other embodiments, the logic control circuit 13 can specifically also use the voltage feedback signal Vc to adjust the adjustable dead time Td, and the adjustable dead time Td is negatively correlated with the voltage feedback signal Vc. Specifically, it can also be the sum of the product of the voltage feedback signal Vc and the dead time control coefficient k3 and the preset maximum dead time Td-max, that is, the adjustable dead time Td = Td-max + k3 * Vc; at this time, the dead time control coefficient k3 is a negative value.

[0077] It should be noted that the preset minimum dead time Td-min and the preset maximum dead time Td-max can specifically be the minimum dead time and the maximum dead time reasonably set according to the physical characteristics of the inverter circuit 101 to determine the minimum switching dead time and the control requirements, and are determined by the actual control scenario. The present application does not make any limitations in this regard.

[0078] Please refer to Figure 5 , Figure 5 which is a schematic structural diagram of the second implementation manner of the soft start control circuit of the present application. The difference between the soft start control circuit in this implementation manner and the first implementation manner of the soft start control circuit provided by the present application is that the charge feedback circuit 21 in the soft start control circuit 20 specifically further includes a current sampling sub-circuit 211, an integration sub-circuit 212, and a voltage bias sub-circuit 213.

[0079] Specifically, the current sampling sub-circuit 211 is coupled to the resonant circuit 102 and the integration sub-circuit 212, and the integration sub-circuit 212 and the voltage bias sub-circuit 213 are coupled to the logic control circuit 23.

[0080] The current sampling sub-circuit 211 is used to sample and obtain the resonant current signal in the resonant output signal from the resonant circuit 102.

[0081] It is understandable that the resonant output signal in the resonant circuit 102 includes a resonant current signal characterizing the input current and a resonant capacitor voltage characterizing the input voltage. The current sampling sub-circuit 211 can specifically obtain the resonant current signal by using any reasonable circuit unit such as a current transformer and / or a sampling resistor, or a current sampling signal having a specific functional relationship with the resonant current signal. The present application does not limit this.

[0082] The integration sub-circuit 212 is configured to receive the resonant current signal sent by the current sampling sub-circuit 211, and perform integration adjustment on the resonant current signal to obtain a phase modulation voltage signal.

[0083] Wherein, the integration adjustment performed by the integration sub-circuit 212 on the resonant current signal can specifically be such that the phase of the phase modulation voltage signal lags behind the resonant current signal by 90°.

[0084] It should be noted that by sampling the resonant current signal of the resonant circuit 102 and then integrating the resonant current signal, the obtained is the charge information of the resonant circuit 102. This charge information can directly characterize the input power of a single cycle and the phase lags behind the resonant current signal by 90°. If the input current is used as the feedback information of the subsequent control signal, it only represents the input current, and when the input voltage changes, it cannot quickly respond to the output. Therefore, in order to characterize the input power and improve the dynamic response speed, after obtaining the resonant current signal, the resonant current signal is further integrated and adjusted to obtain a phase modulation voltage signal.

[0085] Furthermore, the voltage bias sub-circuit 213 is configured to generate a preset bias voltage Vcm. The logic control circuit 23 is configured to receive the phase modulation voltage signal sent by the integration sub-circuit 212 and the preset bias voltage Vcm output by the voltage bias sub-circuit 213 correspondingly, so as to superimpose the preset bias voltage Vcm and the phase modulation voltage signal to obtain a charge feedback signal Vcr.

[0086] It should be noted that the phase modulation voltage signal is actually an alternating current signal that periodically crosses zero. In order to facilitate the generation of subsequent control signals, it is necessary to lift the entire alternating current signal to avoid the existence of negative current.

[0087] In addition, the preset bias voltage Vcm can not only ensure the integrity and stability of the charge feedback signal Vcr, avoid the interference caused by the integration sub-circuit 212 at the zero crossing point, but also take into account the comparison threshold for soft start mode switching at the same time.

[0088] Among them, the preset bias voltage Vcm can be understood as the bias voltage for overall boosting of the AC signal, so as to obtain a charge feedback signal Vcr without negative current through signal superposition, which is used to better ensure the integrity and anti-interference ability of the charge feedback signal Vcr, and the average value of the charge feedback signal Vcr is equal to the value of the preset bias voltage Vcm.

[0089] It can be understood that the logic control circuit 23 specifically enters the third starting stage from the second starting stage when it is determined that the current power supply output signal Vo or the voltage feedback signal Vc is greater than or equal to the product of the average value of the charge feedback signal Vcr and the mode switching control coefficient k1, that is, Vo≥k1*Vcm, or Vc≥k1*Vcm, so as to change from the control strategy corresponding to the second starting stage to the control strategy corresponding to the third starting stage to implement corresponding starting control on the resonant conversion circuit 100.

[0090] In some embodiments, the preset bias voltage Vcm is greater than or equal to half of the difference Verr between the peak and valley of the phase modulation voltage signal, so as to effectively prevent the charge feedback signal Vcr from having negative current.

[0091] In some embodiments, the preset bias voltage Vcm is greater than or equal to half of the difference Verr between the peak and valley of the phase modulation voltage signal and not greater than 1.5V, and the present application does not limit this.

[0092] It can be understood that in this embodiment, the voltage feedback circuit 22 and the logic control circuit 23 are the same as the voltage feedback circuit 12 and the logic control circuit 13 respectively. For details, please refer to Figures 1 - 4 and the relevant text content, which will not be elaborated here.

[0093] Please refer to Figure 6 , Figure 6 is a schematic structural diagram of the third embodiment of the soft start control circuit of the present application. The difference between the soft start control circuit in this embodiment and the first embodiment of the soft start control circuit provided by the present application is that the inverter circuit 101 in the resonant conversion circuit 100 further specifically includes a first switch sub-circuit 1011 and a second switch sub-circuit 1012.

[0094] Specifically, the first switch sub-circuit 1011 is coupled to the second switch sub-circuit 1012, the resonant circuit 102, and the logic control circuit 33, and the second switch sub-circuit 1012 is coupled to the logic control circuit 33.

[0095] Correspondingly, the third control signal specifically further includes a first drive signal Gate_H and a second drive signal Gate_L, where, as Figure 4As shown, in the third startup stage, the logic control circuit 33 is specifically configured to, in the first half cycle of the signal period of each second control signal, in response to the starting moment of this stage, that is, the moment when the power output signal Vo or the voltage feedback signal Vc is greater than or equal to the product of the average value of the charge feedback signal Vcr and the mode switching control coefficient k1, and when each second drive signal Gate_L is adjusted from the first level to the second level, simultaneously perform ramp compensation on the voltage feedback signal Vc using a preset ramp compensation slope to obtain a feedback adjustment signal Vcomp; and delay for a set duration to adjust the first drive signal Gate_H from the second level to the first level; when the voltage amplitudes of the feedback adjustment signal Vcomp and the charge feedback signal Vcr are equal, adjust the first drive signal Gate_H from the first level to the second level.

[0096] In other embodiments, the logic control circuit 33 may specifically also perform ramp compensation on the voltage feedback signal Vc using a preset ramp compensation slope to obtain a feedback adjustment signal Vcomp after delaying for a set duration when each second drive signal Gate_L is adjusted from the first level to the second level. The present application does not limit this.

[0097] It should be noted that the ramp compensation performed on the voltage feedback signal Vc using a preset ramp compensation slope by the logic control circuit 33 when each second drive signal Gate_L is adjusted from the first level to the second level, and the ramp compensation performed on the voltage feedback signal Vc using a preset ramp compensation slope after delaying for a set duration when each second drive signal Gate_L is adjusted from the first level to the second level correspond to different preset ramp compensation slopes, and the preset ramp compensation slope used for the delay is less than the preset ramp compensation slope without delay, which is specifically determined by the actual application scenario. The present application does not limit this.

[0098] Furthermore, in the second half cycle of each signal period, the logic control circuit 33 may specifically copy the first drive signal Gate_H of each first half cycle to obtain the second drive signal Gate_L.

[0099] It can be understood that, as Figure 4 shown, in the first half cycle of each signal period, specifically, the first drive signal Gate_H has a first level state, and in the second half cycle of each signal period, the first drive signal Gate_H remains in the second level state; and the second drive signal Gate_L remains in the second level state in the first half cycle of each signal period, and in the second half cycle of each signal period, corresponding to the level change state of the first drive signal Gate_H in the first half cycle of each signal period, adjusts the level change state of the copied second drive signal Gate_L.

[0100] In some embodiments, the set duration may specifically be the preset minimum dead time Td-min, or may be a specific duration reasonably set according to the preset minimum dead time Td-min and control requirements. The present application does not limit this.

[0101] In some embodiments, the first level may specifically be a high level, and the second level correspondingly is a low level or 0 level; or, the first level may specifically be a low level or 0 level, and the second level correspondingly is a high level, which may specifically be determined by the physical characteristics of each switching tube in the inverter circuit 101. The present application does not limit this.

[0102] Among them, the logic control circuit 33 is further configured to respectively send the first drive signal Gate_H and the second drive signal Gate_L to the first switch sub-circuit 1011 and the second switch sub-circuit 1012, so that the first switch sub-circuit 1011 and the second switch sub-circuit 1012 respectively change their switching states under the action of the first drive signal Gate_H and the second drive signal Gate_L, thereby adjusting the inverter AC signal to adjust the resonance state of the resonance circuit 102.

[0103] In some embodiments, the resonance conversion circuit 100 specifically further includes a switch freewheeling circuit 104 and a regulated output circuit 105; the first switch sub-circuit 1011 specifically includes a first switching tube Q1, and the second switch sub-circuit 1012 includes a second switching tube Q2; the switch freewheeling circuit 104 includes a first freewheeling capacitor C1, a second freewheeling capacitor C2, a first diode D1, and a second diode D2; the resonance circuit 102 includes a first resonance inductor Lr1, a second resonance inductor Lr2, and a resonance capacitor Cr; the power conversion circuit 103 includes an isolation transformer 1031 and a rectifier circuit 1032. The isolation transformer 1031 includes a primary winding RZ0 and a secondary winding RZ1. The secondary winding RZ1 includes a first sub-secondary winding RZ11 and a second sub-secondary winding RZ12. The rectifier circuit 1032 specifically further includes a third diode D3 and a fourth diode D4; the regulated output circuit 105 includes a regulated capacitor Co.

[0104] Among them, the first end of the first switching transistor Q1 is coupled to the first end of the first freewheeling capacitor C1 and the second end of the first diode D1, and is used to be coupled to the first end of the DC power supply 202, that is, the input power supply Vin has a DC output. The second end of the first switching transistor Q1 is coupled to the second end of the first freewheeling capacitor C1, the first end of the first diode D1, the first end of the first resonant inductor Lr1, the first end of the second switching transistor Q2, the first end of the second freewheeling capacitor C2, and the second end of the second diode D2. The second end of the second switching transistor Q2 is coupled to the second end of the second freewheeling capacitor C2, the first end of the second diode D2, the first end of the resonant capacitor Cr and grounded, and is used to be coupled to the second end of the DC power supply 202. The third ends of the first switching transistor Q1 and the second switching transistor Q2 are coupled to the logic control circuit 33.

[0105] The second end of the first resonant inductor Lr1 is coupled to the first end of the second resonant inductor Lr2 and the first end of the primary winding RZ0. The second end of the second resonant inductor Lr2 is coupled to the second end of the primary winding RZ0, the second end of the resonant capacitor Cr, and the current sampling sub-circuit 311.

[0106] The first end of the third diode D3 is coupled to the first end of the first sub-secondary winding RZ11. 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 voltage stabilizing capacitor Co, and is used to be coupled to the first end of the load circuit 201. The first end of the fourth diode D4 is coupled to the second end of the second sub-secondary winding RZ12. The second end of the voltage stabilizing capacitor Co is coupled to the second end of the first sub-secondary winding RZ11 and the first end of the second sub-secondary winding RZ12, and is used to be coupled to the second end of the load circuit 201.

[0107] In other embodiments, the inverter circuit 101 in the resonant conversion circuit 100 may specifically be a full-bridge inverter conversion circuit, and the rectifier circuit 1032 may also be a full-bridge rectifier conversion circuit composed of switching transistors; the switching freewheeling circuit 104 specifically further includes a freewheeling resistor (not shown in the figure), and the regulated output circuit 105 specifically further includes a voltage regulating resistor (not shown in the figure); the resonant conversion circuit 100 may specifically further include a power factor correction circuit (not shown in the figure), and the power factor correction circuit is coupled to the inverter circuit 101 and is used to be coupled to an AC power supply (not shown in the figure), that is, the resonant conversion circuit 100 may specifically be presented by any other reasonable circuit architecture, and the present application does not limit this.

[0108] In some embodiments, the first switching transistor Q1 and the second switching transistor Q2 may specifically be one of MOS transistors, triodes, thin-film transistors, or field-effect transistors or any other reasonable switching transistors, and the present application does not limit this.

[0109] It should be noted that, to distinguish the two ends of each of the above switching tubes other than the control end, one pole is referred to as the first end and the other pole is referred to as the second end. When each switching tube is a triode, the control end, that is, the third end, can specifically be the base, the first end is the collector, and the second end is the emitter; alternatively, the third end can specifically also be the base, the first end is the emitter, and the second end is the collector.

[0110] When each of the above switching tubes is a MOS tube, a thin-film transistor, or a field-effect transistor, the third end can specifically be the gate, the first end is the drain, and the second end is the source; alternatively, the third end can specifically also be the gate, the first end is the source, and the second end is the drain.

[0111] Among them, when each switching tube is a MOS tube, a thin-film transistor, or a field-effect transistor, it can specifically be a composite transistor or a single transistor, and the present application does not make any limitations in this regard.

[0112] In an embodiment, the soft start control circuit 30 specifically further includes a first proportional filtering and correction sub-circuit (not shown in the figure) and a second proportional filtering and correction sub-circuit (not shown in the figure). The first proportional filtering and correction sub-circuit is coupled to the integration sub-circuit 312 and the voltage bias sub-circuit 313 in the charge feedback circuit 31 and is coupled to the logic control circuit 33. The second proportional filtering and correction sub-circuit is coupled to the voltage feedback circuit 32 and the logic control circuit 33.

[0113] Among them, the first proportional filtering and correction sub-circuit is used to obtain the phase modulation voltage signal sent by the integration sub-circuit 312 and the preset bias voltage Vcm output by the voltage bias sub-circuit 313, so as to superimpose the phase modulation voltage signal and the preset bias voltage Vcm to obtain the charge feedback signal Vcr, and then sequentially perform comparison with the reference value, filtering, and correction processing on the charge feedback signal Vcr to obtain the first filtering signal; the second proportional filtering and correction sub-circuit is used to obtain the voltage feedback signal Vc sent by the voltage feedback circuit 32, and sequentially perform comparison with the reference value, filtering, and correction processing on the voltage feedback signal Vc to obtain the second filtering signal, so as to provide a more suitable high-quality input for the logic control circuit 33, thereby effectively optimizing the overall performance and reliability of the soft start control circuit 30 to achieve efficient control.

[0114] The logic control circuit 33 is further configured to receive the first filtering signal and the second filtering signal, so as to obtain a first control signal, a second control signal, and a third control signal by using the first filtering signal and the second filtering signal corresponding to the first starting stage, the second starting stage, and the third starting stage respectively, thereby using the first control signal, the second control signal, and the third control signal to control the inverter circuit 101.

[0115] Please refer to Figure 7 , Figure 7It is a schematic structural diagram of the fourth embodiment of the soft start control circuit of the present application. The difference between the soft start control circuit in this embodiment and the first embodiment of the soft start control circuit provided by the present application is that the charge feedback circuit 41 in the soft start control circuit 40 specifically further includes a voltage sampling sub-circuit 411.

[0116] Specifically, the voltage sampling sub-circuit 411 is coupled to the resonant circuit 102 and the logic control circuit 43 for sampling and obtaining the resonant capacitor voltage in the resonant output signal from the resonant circuit 102.

[0117] Among them, the resonant capacitor voltage can be specifically understood as the resonant capacitor Cr voltage signal to characterize the input power. The logic control circuit 43 can specifically also be used to receive the resonant capacitor voltage sent by the voltage sampling sub-circuit 411 to utilize the resonant capacitor voltage or obtain the charge feedback signal Vcr based on any reasonable adjustment of the resonant capacitor voltage.

[0118] It can be understood that in this embodiment, the voltage feedback circuit 42 and the logic control circuit 43 are the same as the voltage feedback circuit 12 and the logic control circuit 13 respectively. For details, please refer to Figures 1 - 4 and the relevant text content, which will not be elaborated here.

[0119] The present application specifically also adopts a soft start control method. Please refer to Figure 8 , Figure 8 It is a schematic flowchart of the first embodiment of the soft start control method of the present application. Specifically, it can include the following steps:

[0120] S51: Obtain the resonant output signal and the power supply output signal.

[0121] It can be understood that the soft start control method in this embodiment controls the startup of the resonant conversion circuit. Among them, the resonant conversion circuit includes an inverter circuit, a resonant circuit, and an electric energy conversion circuit. The resonant circuit is coupled to the inverter circuit and the electric energy conversion circuit, and the electric energy conversion circuit is used to be coupled to the load circuit; the soft start control circuit includes a charge feedback circuit, a voltage feedback circuit, and a logic control circuit. The charge feedback circuit is used to be coupled to the resonant circuit, the voltage feedback circuit is used to be coupled to the electric energy conversion circuit, and the logic control circuit is coupled to the charge feedback circuit and the voltage feedback circuit and is used to be coupled to the inverter circuit.

[0122] Specifically, the charge feedback circuit is used to sample and obtain the resonant output signal from the resonant circuit; the voltage feedback circuit is used to sample and obtain the power supply output signal output to the load circuit from the electric energy conversion circuit.

[0123] S52: Obtain the charge feedback signal by using the resonant output signal.

[0124] Further, the charge feedback circuit performs one or more of any reasonable signal processing such as voltage regulation, filtering, integral transformation, phase modulation, and voltage biasing based on the resonant output signal, and obtains a charge feedback signal that can reflect the current charge information of the resonant circuit in real time.

[0125] S53: Obtain a voltage feedback signal using the power supply output signal.

[0126] The voltage feedback circuit subtracts the currently obtained power supply output signal from the target reference voltage to obtain the difference therebetween, and then based on the difference, adopts a voltage loop or speed loop control strategy, or a PI controller to obtain a specific output signal for signal regulation, that is, the voltage feedback signal.

[0127] It should be noted that the target reference voltage can be specifically understood as a reference voltage that changes during the entire startup phase, where the power supply output signal monotonically linearly increases from 0 to the target output voltage Vobj in a theoretical state and stabilizes at the target output voltage Vobj.

[0128] S54: Generate a first control signal using a preset rule.

[0129] The logic control circuit is configured to: in the first startup phase, generate a first control signal corresponding to a preset rule based on a preset program.

[0130] In some embodiments, the first startup phase can specifically be determined according to a set duration, that is, starting from the power-on startup of the soft start control circuit, the time period of T0 - T1 for running the set duration is the first startup phase, or it can be determined according to the time period of T0 - T1 corresponding to the output voltage of the power supply output signal Vo rising from 0V to a preset voltage value. This application does not make any limitations in this regard.

[0131] Among them, in the initial stage when the resonant conversion circuit receives the power supply input signal, it is usually necessary to charge the bootstrap capacitor of the high-side switch tube of the inverter circuit, and the charging time needs to ensure that the bootstrap voltage is sufficient. Therefore, the set duration can specifically be determined by the soft start control circuit to satisfy the sufficient bootstrap voltage and leave a reasonable margin. This application does not make any limitations in this regard.

[0132] In addition, the preset rule can be to generate the first control signal using a preset duty cycle, a preset signal frequency, or a preset number of continuous pulses, and stop sending pulses at other times. Any rule can be used to generate the first control signal, and it is specifically set and adjusted according to the actual control scenario of the soft start control circuit to ensure that the bootstrap voltage is sufficient. This application does not make any limitations in this regard.

[0133] S55: Adjust the inverter AC signal using the first control signal.

[0134] The logic control circuit is further configured to send a first control signal to the inverter circuit, so that the inverter circuit changes its switching state under the action of the first control signal to adjust its output signal, that is, the inverter AC signal, thereby adjusting the operation of the resonant circuit.

[0135] S56: After the power-on set duration, detect whether the power supply output signal or the voltage feedback signal is less than the product of the average value of the charge feedback signal and the mode switching control coefficient.

[0136] Further, after the power-on set duration, that is, in the second startup stage, the logic control circuit is further configured to detect whether the power supply output signal or the voltage feedback signal is less than the product of the average value of the charge feedback signal and the mode switching control coefficient.

[0137] Wherein, if the power supply output signal or the voltage feedback signal is less than the product of the average value of the charge feedback signal and the mode switching control coefficient, it corresponds to executing S57 in the second startup stage; if the power supply output signal or the voltage feedback signal is greater than or equal to the product of the average value of the charge feedback signal and the mode switching control coefficient, it corresponds to the third startup stage and executes S59.

[0138] S57: Generate a second control signal by using the maximum preset switching frequency and the adjustable dead time.

[0139] Specifically, in the second startup stage, the logic control circuit is further configured to receive the charge feedback signal sent by the charge feedback circuit and the voltage feedback signal sent by the voltage feedback circuit, and generate a second control signal by using the maximum preset switching frequency and the adjustable dead time corresponding to the resonant circuit.

[0140] In some embodiments, the adjustable dead time is specifically positively correlated with the difference between the power supply output signal and the target reference voltage, that is, when the difference increases, the adjustable dead time also correspondingly increases, so that the duty cycle of the second control signal decreases correspondingly, so that a larger resonant output signal appears in the initial stage of startup, and the corresponding power supply output signal is also larger, and when the difference from the target reference voltage is larger, the resonant output signal can be reduced as quickly as possible to effectively achieve soft startup.

[0141] S58: Adjust the inverter AC signal by using the second control signal.

[0142] The logic control circuit is further configured to send the second control signal to the inverter circuit, so that the inverter circuit changes its switching state under the action of the second control signal to adjust its output signal, that is, the inverter AC signal, thereby adjusting the operation of the resonant circuit.

[0143] S59: The voltage feedback signal is subjected to ramp compensation using a preset ramp compensation slope to obtain a feedback regulation signal.

[0144] Specifically, as Figure 3 and Figure 4 shown, in the third starting stage, the logic control circuit performs ramp compensation on the voltage feedback signal by using the preset ramp compensation slope to obtain a feedback regulation signal.

[0145] S510: Generate a third control signal using the feedback regulation signal and the charge feedback signal.

[0146] The logic control circuit then compares the feedback regulation signal with the charge feedback signal to generate a third control signal for the charge feedback signal based on the difference between the two.

[0147] S511: Regulate the inverter AC signal using the third control signal.

[0148] The logic control circuit is also used to send the third control signal to the inverter circuit, so that the inverter circuit changes its switching state under the action of the third control signal to regulate its output signal, that is, the inverter AC signal, and further regulate the operation of the resonant circuit.

[0149] Please refer to Figure 9 , Figure 9 which Figure 8 is a schematic flowchart of an embodiment of S52 in

[0150] S5211: Obtain the resonant current signal in the resonant output signal.

[0151] Specifically, the charge feedback circuit further includes a current sampling sub-circuit, an integration sub-circuit, and a voltage bias sub-circuit. The current sampling sub-circuit is coupled to the resonant circuit and the integration sub-circuit, and the integration sub-circuit and the voltage bias sub-circuit are coupled to the logic control circuit.

[0152] The current sampling sub-circuit is used to sample and obtain the resonant current signal in the resonant output signal from the resonant circuit.

[0153] S5212: Integrate the resonant current signal to obtain a phase modulation voltage signal.

[0154] The integration sub-circuit is used to receive the resonant current signal sent by the current sampling sub-circuit to perform integration regulation on the resonant current signal to obtain a phase modulation voltage signal.

[0155] Among them, the integral regulation performed by the integral sub-circuit on the resonant current signal can specifically make the phase of the phase modulation voltage signal lag behind the resonant current signal by 90°.

[0156] S5213: Superimpose a preset bias voltage on the phase modulation voltage signal to obtain a charge feedback signal.

[0157] The voltage bias sub-circuit is used to generate a preset bias voltage, and the logic control circuit is used to receive the phase modulation voltage signal sent by the integral sub-circuit and the preset bias voltage correspondingly output by the voltage bias sub-circuit, so as to superimpose the preset bias voltage and the phase modulation voltage signal to obtain a charge feedback signal.

[0158] Please refer to Figure 10 , Figure 10 is Figure 8 a schematic flowchart of another embodiment of S52 in . In one embodiment, the soft start control method of the present application further includes some more specific steps in addition to the above S51-S511. Specifically, the above S52 may further include the following steps:

[0159] S5221: Obtain the resonant capacitor voltage in the resonant output signal.

[0160] Specifically, the charge feedback circuit further includes a voltage sampling sub-circuit, and the voltage sampling sub-circuit is coupled to the resonant circuit and the logic control circuit to sample and obtain the resonant capacitor voltage in the resonant output signal from the resonant circuit.

[0161] S5222: Obtain a charge feedback signal by using the resonant capacitor voltage.

[0162] Among them, the resonant capacitor voltage can be specifically understood as a resonant capacitor voltage signal to represent the input power, and the logic control circuit can specifically be further used to receive the resonant capacitor voltage sent by the voltage sampling sub-circuit to obtain a charge feedback signal by using the resonant capacitor voltage or based on any reasonable adjustment of the resonant capacitor voltage.

[0163] Please refer to Figure 11 , Figure 11 a schematic flowchart of the second implementation manner of the soft start control method of the present application. The soft start control method of this implementation manner is Figure 8 a schematic flowchart of a refined implementation manner of the soft start control method in , and specifically includes the following steps:

[0164] S61: Obtain the resonant output signal and the power supply output signal.

[0165] S62: Obtain a charge feedback signal by using the resonant output signal.

[0166] S63: Obtain a voltage feedback signal by using the power supply output signal.

[0167] S64: Generate a first control signal using a preset rule.

[0168] S65: Adjust the inverted AC signal using the first control signal.

[0169] S66: After the power-on set duration, detect whether the power supply output signal or the voltage feedback signal is less than the product of the average value of the charge feedback signal and the mode switching control coefficient.

[0170] S67: Generate a second control signal using the maximum preset switching frequency and an adjustable dead time.

[0171] S68: Adjust the inverted AC signal using the second control signal.

[0172] Among them, S61, S62, S63, S64, S65, S66, S67, and S68 are the same as Figure 8 S51, S52, S53, S54, S55, S56, S57, and S58 in, for details, please refer to S51, S52, S53, S54, S55, S56, S57, and S58 and their related text descriptions, which will not be elaborated here.

[0173] S69: In the first half cycle of the signal period of each third control signal, when the second drive signal is adjusted from the first level to the second level, delay the set duration or simultaneously use a preset ramp compensation slope to perform ramp compensation on the voltage feedback signal to obtain a feedback adjustment signal.

[0174] Specifically, the inverter circuit in this resonant conversion circuit further specifically includes a first switch sub-circuit and a second switch sub-circuit. The first switch sub-circuit is coupled to the second switch sub-circuit, the resonant circuit, and the logic control circuit, and the second switch sub-circuit is coupled to the logic control circuit.

[0175] Correspondingly, the third control signal specifically further includes a first drive signal and a second drive signal. As Figure 4 shown, in the third startup stage, the logic control circuit is specifically used to, in the first half cycle of the signal period of each second control signal, in response to the start moment of this stage, that is, the moment when the power supply output signal or the voltage feedback signal is greater than or equal to the product of the average value of the charge feedback signal and the mode switching control coefficient, and when each second drive signal is adjusted from the first level to the second level, simultaneously or delay the set duration and use a preset ramp compensation slope to perform ramp compensation on the voltage feedback signal to obtain a feedback adjustment signal.

[0176] S610: Delay the set duration to adjust the first drive signal from the second level to the first level.

[0177] The logic control circuit is also used to adjust the first drive signal from the second level to the first level after a delay for a set duration.

[0178] S611: When the voltage amplitudes of the feedback adjustment signal and the charge feedback signal are equal, adjust the first drive signal from the first level to the second level.

[0179] The logic control circuit is also used to adjust the first drive signal from the first level to the second level when the voltage amplitudes of the feedback adjustment signal and the charge feedback signal are equal.

[0180] S612: In the second half cycle of each signal period, copy the first drive signal of each first half cycle to obtain the second drive signal.

[0181] Further, in the second half cycle of each signal period, the logic control circuit can specifically copy the first drive signal of each first half cycle to obtain the second drive signal.

[0182] S613: Use the first drive signal and the second drive signal to adjust the inverted AC signal.

[0183] Specifically, the logic control circuit is also used to send the first drive signal and the second drive signal to the first switch sub-circuit and the second switch sub-circuit respectively, so that the first switch sub-circuit and the second switch sub-circuit change their switch states under the action of the first drive signal and the second drive signal respectively, thereby adjusting the inverted AC signal to adjust the resonance state of the resonance circuit.

[0184] In the above solution, at the initial stage when the soft start control circuit starts to operate, that is, in the initial stage of power-on startup, different control strategies are adopted at different startup stages to timely suppress the instantaneous impact current to avoid losses to the circuit; at the second startup stage, control is achieved at the maximum preset switching frequency, and the duty cycle is adjusted in response to the difference between the power supply output signal and the target reference voltage, making the dynamic response speed faster and the startup resonant cavity current smaller; and at the third startup stage, control is achieved by comparing the output values of the charge feedback loop and the voltage feedback loop, which can quickly and accurately control the input power according to the output load, further improving the loop dynamic response speed, with a relatively simple control logic, being able to achieve better bandwidth and dynamic performance, and at the same time being able to accurately control the resonant cavity current, making the linearity of the output voltage of the resonant conversion circuit for control better.

[0185] It can be understood that in some other embodiments, the soft start control circuit specifically further includes some other more specific circuit units to be able to correspondingly implement other more specific control methods. For details, please refer to Figures 1 - 7 and the relevant text descriptions, which will not be elaborated here.

[0186] This application specifically also adopts a resonant conversion control circuit. Please refer to Figure 12 , Figure 12 which is a schematic framework diagram of an embodiment of the resonant conversion control circuit of this application. In this embodiment, the resonant conversion control circuit 70 includes a resonant conversion circuit 71 and a soft start control circuit 72.

[0187] Among them, the resonant conversion circuit 71 specifically further includes an inverter circuit 711, a resonant circuit 712, and a power conversion circuit 713. The resonant circuit 712 is coupled to the inverter circuit 711 and the power conversion circuit 713. The power conversion circuit 713 is used to be coupled to the load circuit 201. The soft start control circuit 72 is coupled to the inverter circuit 711, the resonant circuit 712, and the power conversion circuit 713.

[0188] It should be noted that the soft start control circuit 72 described in this embodiment is the soft start control circuit 10, soft start control circuit 20, soft start control circuit 30, or soft start control circuit 40 described in any one of the above embodiments. For details, please refer to Figures 1 - 7 and the relevant text content, which will not be elaborated here.

[0189] This application specifically also adopts an electronic device. Please refer to Figure 13 , Figure 13 which is a schematic framework diagram of an embodiment of the electronic device of this application. In this embodiment, the electronic device 80 includes a housing 81 and a power supply circuit 82 connected to the housing 81.

[0190] Optionally, the electronic device 80 can specifically be any reasonable electronic mechanical device such as a server, a computer, or a smart communication device. This application does not make any limitations in this regard.

[0191] It should be noted that the power supply circuit 82 described in this embodiment is the soft start control circuit 10, soft start control circuit 20, soft start control circuit 30, or soft start control circuit 40 described in any one of the above embodiments, or the resonant conversion control circuit 70. For details, please refer to Figures 1 - 7 , Figure 12 and the relevant text content, which will not be elaborated here.

[0192] The beneficial effects of this application are as follows: Different from the prior art, the charge feedback circuit in the soft start control circuit provided by this application is used to obtain the resonant output signal in the resonant circuit, so as to obtain a charge feedback signal by using the resonant output signal; the voltage feedback circuit obtains the power supply output signal output by the power conversion circuit to the load circuit, so as to obtain a voltage feedback signal by using the difference between the power supply output signal and the target reference voltage; the logic control circuit is configured to: in the first startup stage, generate a first control signal according to a preset rule; in the second startup stage, receive the charge feedback signal sent by the charge feedback circuit and the voltage feedback signal sent by the voltage feedback circuit, and generate a second control signal by using the maximum preset switching frequency and adjustable dead time; wherein, the adjustable dead time is positively correlated with the difference value; in the third startup stage, perform ramp compensation on the voltage feedback signal by using a preset ramp compensation slope to obtain a feedback adjustment signal, so as to generate a third control signal by using the feedback adjustment signal and the charge feedback signal; the logic control circuit is further configured to sequentially send the first control signal, the second control signal, and the third control signal to the inverter circuit, so that the inverter circuit sequentially adjusts the inverter AC signal output to the resonant circuit by using the first control signal, the second control signal, and the third control signal, thereby being able to suppress the instantaneous impact current in a timely manner by adopting different control strategies in different startup stages at the initial stage when the soft start control circuit starts to operate, that is, at the initial stage of power-on startup, so as to avoid losses to the circuit; by implementing control at the maximum preset switching frequency in the second startup stage and adjusting the duty cycle in response to the difference between the power supply output signal and the target reference voltage, the dynamic response speed is faster and the starting resonant cavity current is smaller; and in the third startup stage, control is achieved by comparing the output values of the charge feedback loop and the voltage feedback loop, the input power can be quickly and accurately controlled according to the output load, and the loop dynamic response speed is further improved. The control logic is relatively simple, better bandwidth and dynamic performance can be achieved, and at the same time, the resonant cavity current can be accurately controlled, so that the linearity of the output voltage of the resonant conversion circuit for realizing control is also better.

[0193] The above are only the embodiments of this application, and do not limit the patent scope of this application accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of this application, or directly or indirectly applied in other related technical fields, shall be similarly included in the patent protection scope of this application.

Claims

1. A soft start control circuit, applied to the start control of a resonant conversion circuit, wherein the resonant conversion circuit comprises an inverter circuit, a resonant circuit and an electric energy conversion circuit, wherein the resonant circuit is coupled to the inverter circuit and the electric energy conversion circuit, and the electric energy conversion circuit is used to couple with a load circuit, wherein: The soft start control circuit comprises: A charge feedback circuit, used to couple with the resonant circuit to obtain a resonant output signal in the resonant circuit, and to obtain a charge feedback signal using the resonant output signal; a voltage feedback circuit, coupled to the power conversion circuit to obtain a power output signal output by the power conversion circuit to the load circuit, and to obtain a voltage feedback signal using a difference between the power output signal and a target reference voltage; A logic control circuit, coupled to the charge feedback circuit and the voltage feedback circuit, and used to be coupled to the inverter circuit; Wherein, the logic control circuit is configured as follows: In the first startup phase, a first control signal is generated using a preset rule; In the second startup phase, the charge feedback signal sent by the charge feedback circuit and the voltage feedback signal sent by the voltage feedback circuit are received, and a second control signal is generated by using a maximum preset switching frequency and an adjustable dead time; wherein the adjustable dead time is positively correlated with the difference; In the third startup stage, a preset slope compensation slope is used to perform slope compensation on the voltage feedback signal to obtain a feedback adjustment signal, so as to generate a third control signal using the feedback adjustment signal and the charge feedback signal; The logic control circuit is further used to send the first control signal, the second control signal and the third control signal to the inverter circuit in sequence, so that the inverter circuit sequentially uses the first control signal, the second control signal and the third control signal to adjust the inverter AC signal output to the resonant circuit; Wherein, the charge feedback circuit includes a current sampling subcircuit, an integration subcircuit and a voltage bias subcircuit, the current sampling subcircuit is coupled to the resonant circuit and the integration subcircuit, and the integration subcircuit and the voltage bias subcircuit are coupled to the logic control circuit; the current sampling subcircuit is used to sample and obtain the resonant current signal in the resonant output signal; the integration subcircuit is used to receive the resonant current signal sent by the current sampling subcircuit, so as to integrate and adjust the resonant current signal into a phase-modulated voltage signal; the logic control circuit is used to receive the phase-modulated voltage signal sent by the integration subcircuit and the preset bias voltage output by the voltage bias subcircuit, so as to superimpose the preset bias voltage on the phase-modulated voltage signal to obtain the charge feedback signal.

2. The soft start control circuit according to claim 1, characterized in that: The logic control circuit is configured to: enter the second startup stage from the first startup stage after a power-on setting time; When the power output signal or the voltage feedback signal is greater than or equal to the product of the average value of the charge feedback signal and the mode switching control coefficient, the third startup phase is entered from the second startup phase.

3. The soft start control circuit according to claim 1, characterized in that: The preset bias voltage is greater than or equal to half of the difference between a peak and a trough of the phase modulation voltage signal.

4. The soft start control circuit according to claim 1, characterized in that: The inverter circuit includes a first switch subcircuit and a second switch subcircuit, the first switch subcircuit is coupled to the second switch subcircuit, the resonant circuit and the logic control circuit, and the second switch subcircuit is coupled to the logic control circuit; Wherein, the third control signal includes a first drive signal and a second drive signal, and the logic control circuit is configured to: in the third startup stage, in the first half cycle of each signal cycle of the third control signal, when the second drive signal is adjusted from the first level to the second level, delay for a set time or simultaneously use a preset slope compensation slope to perform slope compensation on the voltage feedback signal to obtain a feedback adjustment signal; and delay for the set time to adjust the first drive signal from the second level to the first level; when the voltage amplitude of the feedback adjustment signal is equal to that of the charge feedback signal, adjust the first drive signal from the first level to the second level; In the second half of each signal cycle, copying the first drive signal of each first half cycle to obtain the second drive signal; The logic control circuit is also used to send the first drive signal and the second drive signal to the first switch sub-circuit and the second switch sub-circuit respectively, so that the first switch sub-circuit and the second switch sub-circuit change the switch state under the action of the first drive signal and the second drive signal respectively to adjust the inverter AC signal.

5. The soft start control circuit according to any one of claims 1 to 4, characterized in that: The adjustable dead time is the sum of the product of the difference and the dead time adjustment coefficient plus the preset minimum dead time.

6. A soft start control method, applied to the start control of a resonant conversion circuit, characterized in that: The soft start control method comprises: Obtaining a resonant output signal and a power supply output signal; The charge feedback signal is obtained by using the resonant output signal; wherein the step of obtaining the charge feedback signal by using the resonant output signal comprises: obtaining a resonant current signal in the resonant output signal; integrating and adjusting the resonant current signal into a phase-modulated voltage signal; and superimposing a preset bias voltage on the phase-modulated voltage signal to obtain the charge feedback signal; Obtaining a voltage feedback signal using the power supply output signal; Generate a first control signal using a preset rule; Using the first control signal to adjust the inverter AC signal; After the power-on setting time, detecting whether the power output signal or the voltage feedback signal is less than the product of the average value of the charge feedback signal and the mode switching control coefficient; If the power supply output signal or the voltage feedback signal is less than the product, a second control signal is generated using a maximum preset switching frequency and an adjustable dead time; wherein the adjustable dead time is positively correlated with the voltage feedback signal; Using the second control signal to adjust the inverter AC signal; If the power supply output signal or the voltage feedback signal is greater than or equal to the product, performing slope compensation on the voltage feedback signal using a preset slope compensation slope to obtain a feedback regulation signal; generating a third control signal using the feedback adjustment signal and the charge feedback signal; The inverter AC signal is regulated using the third control signal.

7. The soft start control method according to claim 6, characterized in that: The third control signal includes a first drive signal and a second drive signal, and the step of using a preset slope compensation slope to perform slope compensation on the voltage feedback signal to obtain a feedback adjustment signal includes: In the first half of each signal cycle of the third control signal, when the second driving signal is adjusted from the first level to the second level, a delay of a set time length or a preset slope compensation slope is used to perform slope compensation on the voltage feedback signal to obtain a feedback adjustment signal; The step of generating a third control signal by using the feedback adjustment signal and the charge feedback signal comprises: Delaying the set time length to adjust the first driving signal from the second level to the first level; When the voltage amplitudes of the feedback adjustment signal and the charge feedback signal are equal, adjusting the first drive signal from the first level to the second level; In the second half of each signal cycle, copying the first drive signal of each first half cycle to obtain the second drive signal; The step of regulating the inverter AC signal by using the third control signal comprises: The inverter AC signal is adjusted using the first drive signal and the second drive signal.

8. A resonant conversion control circuit, characterized in that: The resonant conversion control circuit includes a resonant conversion circuit and a soft start control circuit, the resonant conversion circuit includes an inverter circuit, a resonant circuit and an electric energy conversion circuit, the resonant circuit is coupled to the inverter circuit and the electric energy conversion circuit, the electric energy conversion circuit is used to couple with a load circuit, and the soft start control circuit is coupled to the inverter circuit, the resonant circuit and the electric energy conversion circuit; Wherein, the soft start control circuit is the soft start control circuit as described in any one of claims 1-5.

9. An electronic device, characterized in that: The electronic device comprises a housing and a power circuit connected to the housing; Wherein, the power supply circuit is a soft start control circuit as described in any one of claims 1 to 5, or a resonant conversion control circuit as described in claim 8.

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