A digital-analog hybrid buck-boost circuit control method and system

Abstract

The application belongs to the technical field of switching power supply, and discloses a digital-analog hybrid Buck-Boost circuit control method, wherein a peak current signal and an output voltage signal of a power conversion circuit are collected, and a PWM driving signal is generated by an analog PWM controller, so that the module has double-loop control of peak current sampling and output voltage sampling under high-voltage and high-power working conditions, fast transient response is realized, the input voltage and the output voltage are compared through hardware sampling, and a difference state is output to a digital control circuit in the form of a level signal, so that the digital control circuit can quickly and accurately judge the input-output voltage relationship, a digital control signal is output by the digital control circuit, and the PWM driving signal and the digital control signal are output to the power conversion circuit after logic operation by a signal conditioning circuit, in the whole control link, the analog control is responsible for fast response and voltage stabilization adjustment, the digital control is responsible for mode judgment and switching control, and the two are fused through the signal conditioning circuit to drive the power conversion circuit.

Description

Technical Field

[0001] This invention belongs to the field of switching power supply technology, specifically a mixed-signal Buck-Boost circuit control method. Background Technology

[0002] In the field of power conversion technology, Buck-Boost power modules are widely used in scenarios requiring step-up / step-down voltage regulation. With the development of power electronics technology, the control methods for Buck-Boost power modules have become increasingly mature, mainly including two types: digital circuit control and analog circuit control.

[0003] Digital circuit control methods suffer from control delays introduced by ADC sampling, algorithm calculation, and PWM refresh, resulting in limited loop bandwidth, insufficient instantaneous response, and low efficiency under light load conditions. While analog circuit control methods eliminate sampling and calculation delays, offer high dynamic response bandwidth, and good efficiency under light load, smooth transitions between Buck-Boost modes are difficult, especially with wide-range inputs and outputs. Oscillations and increased ripple are common at mode transitions, and protection functions are fixed, making fault recording, communication, and remote monitoring difficult.

[0004] In existing technologies, digital control schemes achieve closed-loop control through ADC sampling, digital algorithm calculation, and PWM refresh, offering high precision and flexible control, but inherent time delays exist. Analog control schemes directly generate PWM drive signals through peak current sampling and output voltage feedback, eliminating sampling and calculation delays and providing fast response, but limiting mode switching and protection functions. The two schemes are used independently and do not effectively complement each other.

[0005] The aforementioned existing technologies all employ a single control method. Digital control suffers from insufficient transient response and low efficiency under light loads due to delays, while analog control exhibits output ripple and inrush current issues due to unsmooth mode switching. A single control method cannot simultaneously achieve rapid transient response, high efficiency under light loads, smooth mode switching, and intelligent monitoring functions. There is an urgent need for a control method that combines the advantages of both digital and analog control, achieving high-bandwidth, fast response while ensuring smooth switching across a wide range of inputs and outputs and comprehensive protection and monitoring functions. Summary of the Invention

[0006] This invention provides a mixed-signal Buck-Boost circuit control method that solves the problems of slow digital control response and unsmooth analog control switching in existing Buck-Boost modules, making it impossible to achieve both simultaneously.

[0007] To achieve the above objectives, this invention provides a mixed-signal Buck-Boost circuit control method, comprising the following steps: acquiring the peak current signal and output voltage signal of the power conversion circuit; generating a PWM drive signal based on the peak current signal and the output voltage signal; sampling and comparing the input voltage and output voltage of the power conversion circuit, and outputting the difference between the input voltage and the output voltage as a level signal to the digital control circuit; the digital control circuit determining the operating state of the module based on the difference state and outputting a digital control signal; a signal conditioning circuit performing logical operations on the PWM drive signal and the digital control signal, and outputting a conditioned drive signal; and outputting the conditioned drive signal to the power conversion circuit respectively.

[0008] According to one embodiment of the present invention, the power conversion circuit adopts a two-switch Buck-Boost topology, including a first switch, a second switch, a first diode, a second diode, a power inductor, and a sampling resistor; the first switch and the first diode are connected in series to form a first bridge arm, the second switch and the second diode are connected in series to form a second bridge arm, the first bridge arm is connected in parallel across the input capacitor, one end of the power inductor is connected to the midpoint of the first bridge arm and the other end is connected to the midpoint of the second bridge arm, the output capacitor is connected in parallel across the second bridge arm, and the sampling resistor is disposed between the negative terminal of the first bridge arm and the negative terminal of the second bridge arm.

[0009] According to one embodiment of the present invention, the signal conditioning circuit includes an OR gate and an AND gate, wherein the PWM drive signal is respectively input to the first input terminal of the OR gate and the first input terminal of the AND gate, and the digital control signal is respectively input to the second input terminal of the OR gate and the second input terminal of the AND gate.

[0010] According to one embodiment of the present invention, when the input voltage is higher than the output voltage by 20V, the digital control circuit determines that the power conversion circuit is in a step-down state, and the digital control signal output to the OR gate is low level, and the digital control signal output to the AND gate is low level; the OR gate outputs a signal that is the same as the PWM drive signal, and the AND gate outputs a low level; the first switch is in the PWM switching state, and the second switch is in the normally off state.

[0011] According to one embodiment of the present invention, when the input voltage is lower than the output voltage of 20V, the digital control circuit determines that the power conversion circuit is in a boost state, the digital control signal output to the OR gate is high level, the digital control signal output to the AND gate is high level, the OR gate outputs a high level, the AND gate outputs a signal that is the same as the PWM drive signal, the first switch is in a normally open state, and the second switch is in a PWM switching state.

[0012] According to one embodiment of the present invention, when the time difference between the input voltage and the output voltage is less than or equal to 20V, the digital control circuit determines that the power conversion circuit is in an intermediate state, and the digital control signal output to the OR gate is a first duty cycle signal, and the digital control signal output to the AND gate is a second duty cycle signal; both the first switch and the second switch are in PWM switching state.

[0013] According to one embodiment of the present invention, the first duty cycle is greater than 50%, and the second duty cycle is less than 50%.

[0014] According to one embodiment of the present invention, when the digital control circuit switches between different operating states, it controls the conduction and cutoff of the first switch and the second switch by gradually changing the duty cycle.

[0015] According to one embodiment of the present invention, the first switching transistor and the second switching transistor are SiC MOSFETs, and the first diode and the second diode are SiC Schottky diodes.

[0016] This invention also provides a hybrid analog-digital Buck-Boost circuit control system for implementing the control method of any one of claims 1-9, comprising: a power conversion circuit employing a two-switch Buck-Boost topology, including a first switch, a second switch, a first diode, a second diode, a power inductor, and a sampling resistor; an analog PWM controller for generating a PWM drive signal based on the peak current signal acquired by the sampling resistor and the output voltage signal of the power conversion circuit; a hardware sampling circuit for sampling and comparing the input voltage and output voltage of the power conversion circuit, and outputting the difference state between the input voltage and the output voltage; a digital control circuit for receiving the difference state and determining the operating state of the module, and outputting a digital control signal; a signal conditioning circuit for performing logical operations on the PWM drive signal and the digital control signal, and outputting a conditioned drive signal; and an isolation driver for outputting the conditioned drive signal to the control terminals of the first switch and the second switch of the power conversion circuit, respectively.

[0017] Compared with existing technologies, the present invention has the following advantages: The present invention provides a mixed-signal Buck-Boost circuit control method. By acquiring the peak current signal and output voltage signal of the power conversion circuit and generating a PWM drive signal by an analog PWM controller, the module has dual-loop control of peak current sampling and output voltage regulation sampling under high voltage and high power conditions, realizing fast instantaneous response. By hardware sampling and comparing the input voltage and output voltage and outputting the difference status to the digital control circuit in the form of a level signal, the digital control circuit can quickly and accurately determine the input and output voltage relationship, avoiding the problems caused by ADC sampling and software judgment in the digital circuit. The introduction of delays and misjudgments is addressed by outputting digital control signals through the digital control circuit. The signal conditioning circuit performs logical operations on the PWM drive signal and the digital control signal before outputting them to the power conversion circuit. This allows the digital control signal to adjust the logic output in real time according to the input-output voltage difference, controlling the switching transistor to be in PWM switching, normally open, or normally closed states. In the entire control chain, analog control is responsible for fast response and voltage regulation, while digital control is responsible for mode judgment and switching control. The two are integrated through the signal conditioning circuit to drive the power conversion circuit, enabling the Buck-Boost module to combine the high bandwidth and fast response of analog control with the smooth switching and intelligent monitoring capabilities of digital control. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of a mixed-signal Buck-Boost circuit control method according to an embodiment of the present invention; Figure 2 This is a circuit diagram of a mixed-signal Buck-Boost circuit control system according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the signal conditioning circuit according to an embodiment of the present invention; Figure 4 This is a waveform diagram of the module operating in boost mode according to an embodiment of the present invention; Figure 5 This is a waveform diagram of the module operating in buck mode according to an embodiment of the present invention; Figure 6 This is a waveform diagram of the module operating in buck-boost mode according to an embodiment of the present invention; Figure 7 This is another design method for the buck-boost main power circuit according to an embodiment of the present invention. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] See Figure 1 In one embodiment of the present invention, a mixed-signal Buck-Boost circuit control method is provided, which solves the technical problems of slow digital control response and unsmooth analog control switching in existing Buck-Boost modules.

[0025] Step S1: Acquire the peak current signal and output voltage signal of the power conversion circuit.

[0026] Specifically, the power conversion circuit adopts a two-switch Buck-Boost topology, including a first switch Q1, a second switch Q2, a first diode D1, a second diode D2, a power inductor L, and a sampling resistor R1. The first switch Q1 and the first diode D1 are connected in series to form the first bridge arm, and the second switch Q2 and the second diode D2 are connected in series to form the second bridge arm. The first bridge arm is connected in parallel across the input capacitor C1. One end of the power inductor L is connected to the midpoint of the first bridge arm, and the other end is connected to the midpoint of the second bridge arm. The output capacitor C2 is connected in parallel across the second bridge arm. The sampling resistor R1 is positioned between the negative terminals of the first and second bridge arms. The signal on the sampling resistor R1 is differentially amplified by operational amplifier OP1, and the resulting peak current sampling signal is sent to the analog PWM controller. The output voltage is divided by voltage divider networks R2 and R3 and then connected to the feedback terminal of the analog PWM controller.

[0027] Explanatory: A two-switch Buck-Boost topology using SiC MOSFETs and SiC Schottky diodes is employed. SiC devices offer high voltage withstand capability, high switching speed, low on-resistance, and zero reverse recovery, enabling high-voltage, wide-range input designs, improving module efficiency, and facilitating miniaturization in high-power designs. Sampling resistors and voltage divider networks collect current and voltage signals respectively, providing feedback for analog control.

[0028] Step S2: Generate a PWM drive signal based on the peak current signal and the output voltage signal.

[0029] Specifically, the analog PWM controller U1 receives the peak current sampling signal from operational amplifier OP1 and the output voltage feedback signal from the voltage divider network. Through peak current control and output voltage feedback control, it generates a PWM drive signal for regulated output control. The analog PWM controller employs cycle-by-cycle current limiting and automatic frequency hopping control under light load.

[0030] Explanatory: Analog control has no sampling and computation delay, high dynamic response bandwidth, and good efficiency under light load, making it particularly suitable for the fast transient response and high efficiency requirements of high voltage and high power modules under light load.

[0031] Step S3: Sample and compare the input voltage and output voltage of the power conversion circuit, and output the difference between the input voltage and the output voltage as a level signal to the digital control circuit.

[0032] Specifically, the hardware sampling circuit U3 samples the input voltage by voltage divider and simultaneously samples the output voltage, compares the two, and outputs the difference between the input and output voltages to the digital control circuit U2 in a high or low level manner.

[0033] Explanatory: The difference between the input and output voltages determines whether the module should operate in buck, boost, or intermediate mode. The hardware sampling circuit directly compares the two voltages, which is faster and more accurate than purely digital judgment. This avoids the problem of digital circuit misinterpretation when both input and output voltages are adjustable, and enables fast state recognition under wide input and output ranges.

[0034] Step S4: The digital control circuit determines the working state of the module based on the difference state and outputs a digital control signal.

[0035] Specifically, the digital control circuit U2 receives the differential status level signal provided by the hardware sampling circuit U3, determines whether the module should be in a buck, boost, or intermediate state, and outputs the corresponding digital control signal to the signal conditioning circuit U4. During the state switching process, the digital control circuit gradually turns the duty cycle on and off to ensure the stability of the output voltage and input current during the state switching.

[0036] Explanatory: Digital control circuits are responsible for mode determination and switching control. Their advantages lie in flexible control, fault recording, communication and remote monitoring functions.

[0037] Step S5: The signal conditioning circuit performs logical operations on the PWM drive signal and the digital control signal, and outputs the conditioned drive signal.

[0038] Specifically, such as Figure 3 As shown, the signal conditioning circuit U4 includes an OR gate U4-1 and an AND gate U4-2. The PWM drive signal output from the analog PWM controller U1 is input to the first input terminal of the OR gate U4-1 and the first input terminal of the AND gate U4-2, respectively. The digital control signal output from the digital control circuit U2 is input to the second input terminal of the OR gate U4-1 and the second input terminal of the AND gate U4-2, respectively. The output of the OR gate U4-1 serves as the drive signal source for the first switch Q1, and the output of the AND gate U4-2 serves as the drive signal source for the second switch Q2.

[0039] When the input voltage is 20V higher than the output voltage, the digital control circuit U2 determines that the module is in buck mode. The digital control signal output to OR gate U4-1 is low, and the digital control signal output to AND gate U4-2 is also low. OR gate U4-1 outputs the same signal as the PWM drive signal of the analog PWM controller U1, and AND gate U4-2 outputs a low level. The first switch Q1 is in PWM switching mode, and the second switch Q2 is normally off. The module is in buck operation mode. (See also...) Figure 5 The diagram shows the waveform of the module in buck mode.

[0040] When the input voltage is lower than the output voltage by 20V, the digital control circuit U2 determines that the module is in boost mode. The digital control signal output to OR gate U4-1 is high, and the digital control signal output to AND gate U4-2 is also high. OR gate U4-1 outputs a high level, and AND gate U4-2 outputs the same signal as the PWM drive signal of the analog PWM controller U1. The first switch Q1 is normally open, and the second switch Q2 is in PWM switching mode, meaning the module is in boost mode. (See also...) Figure 4 The diagram shows the waveform of the module in boost mode.

[0041] In one possible implementation, when the time difference between the input voltage and the output voltage is less than or equal to 20V, the digital control circuit U2 determines that the module is in an intermediate state. The digital control signal output to OR gate U4-1 is the first duty cycle signal, and the digital control signal output to AND gate U4-2 is the second duty cycle signal. The first duty cycle is greater than 50%, and the second duty cycle is less than 50%. Both the first switch Q1 and the second switch Q2 are in PWM switching mode, and the module is in a mixed-signal modulation buck-boost operating state. See also Figure 6 The diagram shows the module's operating waveforms in buck-boost mode. In this mode, the output voltage can be stably controlled at the set value through the mixed-signal modulated drive signal, while improving the efficiency of the intermediate state.

[0042] Explanation: OR and AND gates perform logic operations on analog PWM drive signals and digital control signals to achieve mixed-signal control. This conditioning method allows the digital control signal to adjust the logic output in real time according to the input-output voltage relationship, controlling the switching transistor to be in PWM switching, normally open, or normally closed state, achieving smooth switching between Buck and Boost modes.

[0043] Step S6: Output the conditioned drive signals to the power conversion circuit respectively.

[0044] Specifically, the conditioned drive signal is isolated and amplified by the isolation driver U5, and then output to the control terminals of the first switch Q1 and the second switch Q2 respectively, driving Q1 and Q2 to turn on and off, thereby realizing the buck-boost function of the module.

[0045] Explanatory: Isolation drivers ensure electrical isolation between control circuits and power circuits, improving system safety.

[0046] Validity verification In one possible implementation, the technical effects and feasibility of the present invention are illustrated using a high-voltage, high-power Buck-Boost module as an example.

[0047] This module features a wide input voltage range and an equally wide adjustable output voltage, delivering power in the kilowatt range. The power conversion circuit employs a two-switch Buck-Boost topology composed of SiC MOSFETs and SiC Schottky diodes. The control circuit consists of an analog PWM controller, hardware sampling circuitry, digital control circuitry, signal conditioning circuitry, and an isolation driver. Test scenarios included buck mode, boost mode, intermediate states, and dynamic switching between the three modes.

[0048] The analog PWM controller's peak current sampling frequency is consistent with the power switching frequency, and the cycle-by-cycle current limiting function provides real-time response. The hardware sampling circuit performs voltage division and comparison on the input and output voltages, outputting the difference status as high or low levels. The digital control circuit updates the digital control signal every few switching cycles based on the difference status. The logic delays of the OR and AND gates in the signal conditioning circuit are in the nanosecond range, and the isolation driver's propagation delay is in the tens of nanoseconds. The power switching transistors are SiC MOSFETs, and the diodes are SiC Schottky diodes.

[0049] After the system powers on, the hardware sampling circuit samples the input and output voltages in real time, outputting the difference status as a level signal to the digital control circuit. The digital control circuit determines the operating state based on the difference status and outputs the corresponding digital control signal. Simultaneously, the analog PWM controller generates a PWM drive signal based on the peak current sampling and output voltage feedback. The signal conditioning circuit performs OR and AND operations on the PWM drive signal and the digital control signal, outputting the conditioned drive signal. The isolation drivers output the conditioned drive signal to Q1 and Q2 respectively. When a change in input voltage causes a change in the difference status, the digital control circuit adjusts the digital control signal, causing the drive logic of Q1 and Q2 to switch accordingly, achieving a smooth mode transition.

[0050] After adopting the hybrid analog-digital control method of this invention, the measured performance of the module is as follows: In buck mode, the analog PWM controller adjusts independently, with a dynamic response time of less than 100 microseconds, and the light-load efficiency is improved by approximately 5%-8% compared to pure digital control. In boost mode, the analog PWM controller also adjusts independently, with response speed and efficiency consistent with buck mode. In the intermediate state, through hybrid analog-digital modulation with a first duty cycle greater than 50% and a second duty cycle less than 50%, the output voltage ripple is reduced by approximately 30%-50% compared to pure analog control, and the intermediate-state efficiency is improved by approximately 5%-10% compared to pure analog control. During mode switching, the digital control circuit gradually changes the duty cycle to keep the output voltage fluctuation within ±3% of the set value, with no inrush current, achieving smooth switching. Simultaneously, the digital control circuit implements fault recording, communication, and remote monitoring functions, with a protection response time of less than 1 microsecond.

[0051] Verification results show that the hybrid analog-digital control method enables the Buck-Boost module to simultaneously possess the advantages of analog control (high bandwidth, fast response, and high efficiency under light load) and digital control (smooth switching and intelligent monitoring), effectively solving the technical problems that existing single control methods cannot achieve.

[0052] In an alternative implementation, the power conversion circuit may also employ a four-switch Buck-Boost topology, such as... Figure 7As shown, by using SiC MOSFETs as the switching transistors Q1 to Q4 in the diagram, a high-voltage, wide-range input / output power supply can also be achieved. However, the drive circuit of the four-switch topology is more complex, and the switching transistor losses are significantly increased compared to the two-switch topology. See Figure 2 In another embodiment of the present invention, a hybrid analog-digital Buck-Boost circuit control system is provided, comprising: a power conversion circuit employing a two-switch Buck-Boost topology, including a first switch Q1, a second switch Q2, a first diode D1, a second diode D2, a power inductor L, and a sampling resistor R1; an analog PWM controller U1, used to generate a PWM drive signal based on the peak current signal collected by the sampling resistor R1 and the output voltage signal of the power conversion circuit; a hardware sampling circuit U3, used to sample and compare the input voltage and output voltage of the power conversion circuit, and output the difference state between the input voltage and the output voltage; a digital control circuit U2, used to receive the difference state and determine the working state of the module, and output a digital control signal; a signal conditioning circuit U4, used to perform logical operations on the PWM drive signal and the digital control signal, and output a conditioned drive signal; and an isolation driver U5, used to output the conditioned drive signal to the control terminals of the first switch Q1 and the second switch Q2 of the power conversion circuit, respectively.

[0053] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0054] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A mixed-signal Buck-Boost circuit control method, characterized in that, Includes the following steps: Acquire the peak current signal and output voltage signal of the power conversion circuit; A PWM drive signal is generated based on the peak current signal and the output voltage signal; The input and output voltages of the power conversion circuit are sampled and compared, and the difference between the input and output voltages is output to the digital control circuit as a level signal. The digital control circuit determines the working state of the module based on the difference state and outputs a digital control signal. The signal conditioning circuit performs logical operations on the PWM drive signal and the digital control signal, and outputs the conditioned drive signal. The conditioned drive signals are output to the power conversion circuit respectively.

2. The mixed-signal Buck-Boost circuit control method according to claim 1, characterized in that, The power conversion circuit adopts a two-switch Buck-Boost topology, including a first switch, a second switch, a first diode, a second diode, a power inductor, and a sampling resistor. The first switch and the first diode are connected in series to form a first bridge arm, and the second switch and the second diode are connected in series to form a second bridge arm. The first bridge arm is connected in parallel across the input capacitor. One end of the power inductor is connected to the midpoint of the first bridge arm, and the other end is connected to the midpoint of the second bridge arm. The output capacitor is connected in parallel across the second bridge arm, and the sampling resistor is positioned between the negative terminals of the first and second bridge arms.

3. The mixed-signal Buck-Boost circuit control method according to claim 2, characterized in that, The signal conditioning circuit includes an OR gate and an AND gate. The PWM drive signal is input to the first input terminal of the OR gate and the first input terminal of the AND gate, respectively. The digital control signal is input to the second input terminal of the OR gate and the second input terminal of the AND gate, respectively.

4. The mixed-signal Buck-Boost circuit control method according to claim 3, characterized in that, When the input voltage is higher than the output voltage of 20V, the digital control circuit determines that the power conversion circuit is in a step-down state. The digital control signal output to the OR gate is low, the digital control signal output to the AND gate is low, the OR gate outputs the same signal as the PWM drive signal, the AND gate outputs a low level, the first switch is in the PWM switching state, and the second switch is in the normally off state.

5. The mixed-signal Buck-Boost circuit control method according to claim 3, characterized in that, When the input voltage is lower than the output voltage of 20V, the digital control circuit determines that the power conversion circuit is in the boost state, the digital control signal output to the OR gate is high level, the digital control signal output to the AND gate is high level, the OR gate outputs a high level, the AND gate outputs a signal that is the same as the PWM drive signal, the first switch is in the normally open state, and the second switch is in the PWM switching state.

6. The mixed-signal Buck-Boost circuit control method according to claim 3, characterized in that, When the time difference between the input voltage and the output voltage is less than or equal to 20V, the digital control circuit determines that the power conversion circuit is in an intermediate state, and the digital control signal output to the OR gate is the first duty cycle signal, and the digital control signal output to the AND gate is the second duty cycle signal; both the first switch and the second switch are in PWM switching state.

7. The mixed-signal Buck-Boost circuit control method according to claim 6, characterized in that, The first duty cycle is greater than 50%, and the second duty cycle is less than 50%.

8. The mixed-signal Buck-Boost circuit control method according to claim 2, characterized in that, When the digital control circuit switches between different operating states, it controls the conduction and cutoff of the first and second switching transistors by gradually changing the duty cycle.

9. A mixed-signal Buck-Boost circuit control method according to claim 2, characterized in that, The first and second switching transistors are SiC MOSFETs, and the first and second diodes are SiC Schottky diodes.

10. A hybrid analog-digital Buck-Boost circuit control system, characterized in that, A method for controlling a mixed-signal Buck-Boost circuit according to any one of claims 1-9 includes: The power conversion circuit adopts a two-switch Buck-Boost topology, including a first switching transistor, a second switching transistor, a first diode, a second diode, a power inductor, and a sampling resistor; An analog PWM controller is used to generate a PWM drive signal based on the peak current signal acquired by the sampling resistor and the output voltage signal of the power conversion circuit; The hardware sampling circuit is used to sample and compare the input voltage and output voltage of the power conversion circuit, and output the state of the difference between the input voltage and the output voltage. The digital control circuit is used to receive the difference status and determine the working status of the module, and output digital control signals; The signal conditioning circuit is used to perform logical operations on the PWM drive signal and the digital control signal, and output the conditioned drive signal. An isolation driver is used to output the conditioned drive signal to the control terminals of the first and second switching transistors of the power conversion circuit, respectively.

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