Soft switching control method and Boost converter

Abstract

The invention discloses a soft switching control method and a Boost converter. According to the state of the current of the energy storage inductor in the first mode and the real-time states of the switching tube stray capacitor C1 and the follow current switching stray capacitor C2, the duration of each mode and the current corresponding to the energy storage inductor are calculated respectively; generating a control signal according to the duration of each mode and the current corresponding to the energy storage inductor; monitoring a current iLr corresponding to the energy storage inductor; when it is monitored that the current iLr of the energy storage inductor is the first current value In1, the Boost converter is controlled to be sequentially switched to other modes from the first mode according to the control signal, and soft switching control over the Boost converter is achieved. According to the invention, a wider zero-voltage turn-on range can be provided, so that the adaptability and the stability of the system are improved; and the MCU sampling rate limitation can be broken through, so that the input signal can be responded and processed more quickly, and the real-time performance and the accuracy of the system are improved.

Description

Technical Field

[0001] The present application relates to the technical field of inverter control, and particularly to a soft-switching control method and a Boost converter. Background Art

[0002] Due to its advantages such as simple structure, low cost, and easy control, the Boost circuit is widely used in photovoltaic power generation, hybrid vehicles, and energy storage systems. To meet the design requirements of high power, high efficiency, high integration, small size, and light weight, increasing the switching frequency is a direct method. However, high-frequency operation will bring greater switching losses and electromagnetic interference problems. Soft-switching technology improves the feasibility of high-frequency operation by reducing switching losses and electromagnetic interference. Traditional soft-switching uses an auxiliary network to achieve zero-voltage or zero-current switching, but this auxiliary network increases the circuit complexity, volume, and cost. Therefore, the soft-switching technology without an auxiliary network has become a research hotspot. Among them, TCM (Transition Conduction Mode, continuous conduction mode) control is a common method, which realizes soft-switching through the resonance of the inductor reverse current.

[0003] However, the existing converters based on TCM control have problems such as limited zero-voltage turn-on range and difficulty in breaking through the existing MCU sampling rate limit for the switching frequency. Summary of the Invention

[0004] An object of an embodiment of the present application is to provide a soft-switching control method and a Boost converter to solve the technical problems that the current soft-switching control strategy has a limited zero-voltage turn-on range and difficulty in breaking through the existing MCU sampling rate limit for the switching frequency.

[0005] To solve the above technical problems, a technical solution adopted in an embodiment of the present application is: to provide a soft-switching control method applied to a Boost converter, the Boost converter includes an input circuit module, a main power switch module, an energy storage and transmission module, a freewheeling loop module, and an output filter module. The input circuit module includes an input power supply. The main power switch module includes a power switch tube Q1, a switch tube parasitic capacitor C1, and a body diode D1. The energy storage and transmission module includes a storage inductor. The freewheeling loop module includes a freewheeling switch tube Q2, a freewheeling switch parasitic capacitor C2, and a freewheeling body diode D2. The output filter module includes a storage filter capacitor EC2 and a load resistor R L, the positive pole of the input power supply is connected to one end of the energy storage inductor, the other end of the energy storage inductor is connected between the drain of the power switch Q1 and the source of the freewheeling switch Q2, the source of the power switch Q1 is respectively connected to the negative pole of the input power supply and one end of the output filter module, the drain of the freewheeling switch Q2 is connected to the other end of the output filter module, the energy storage filter capacitor EC2 and the load resistor R L are connected in parallel to smooth the output voltage and supply it to the load. The Boost converter further includes a control module, and the control module is used to connect the gates of the power switch Q1 and the freewheeling switch Q2. The method includes: the control module calculates the duration of each mode and the current corresponding to the energy storage inductor respectively according to the state of the current of the energy storage inductor, the real-time state of the parasitic capacitance C1 of the switch tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch in the first mode, wherein, in the first mode, the states of the power switch Q1 and the freewheeling switch Q2 are in the initialization state; generate a control signal according to the duration of each mode and the current corresponding to the energy storage inductor; monitor the current i Lr corresponding to the energy storage inductor; when it is monitored that the current i Lr corresponding to the energy storage inductor reaches the preset first current value I n1 , the control module controls the Boost converter to sequentially switch from the first mode to other modes according to the control signal to realize the soft-switching control of the Boost converter; wherein, the first current value I n1 satisfies a first preset condition, and the first preset condition is set according to the terminal voltage of the energy storage filter capacitor EC2, the parasitic capacitance C1 of the switch tube, and the energy storage inductor.

[0006] Optionally, the first current value I n1 satisfies a first preset condition, and the first preset condition is set according to the terminal voltage of the energy storage filter capacitor EC2, the parasitic capacitance C1 of the switch tube, and the energy storage inductor, including: determining the first preset condition according to the following formula, and the formula is:

[0007]

[0008] wherein, V o is the terminal voltage of the energy storage filter capacitor EC2, C oss is the capacitance value of the parasitic capacitance C1 of the switch tube, and L r is the inductance value corresponding to the energy storage inductor.

[0009] Optionally, the start time of the first mode is t0, and the end time is t1. In the first mode, the switching period control of the power switch Q1 and the freewheeling switch Q2 includes: at the moment t0, iLr decreases to zero, and the voltage difference between the terminal voltage V0 of the output energy storage filter capacitor EC2 and the input voltage V of the input power supply reversely charges the energy storage inductor, and i in starts to increase linearly in the negative direction. At time t1, i Lr starts to increase linearly in the negative direction. At time t1, i Lr negatively increases to a preset first current value I n1 and then the freewheeling switch tube Q2 is turned off.

[0010] Optionally, in the first mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor, the real-time states of the parasitic capacitance C1 of the switch tube and the parasitic capacitance C2 of the freewheeling switch in the first mode, including: calculating the current i Lr (t) corresponding to the energy storage inductor in the first mode according to the following formula (1), and calculating the duration Δt1 of the first mode according to the following formula (2);

[0011] The formula (1) is:

[0012]

[0013] The formula (2) is:

[0014]

[0015] where L r is the inductance value corresponding to the energy storage inductor.

[0016] Optionally, the other modes include a second mode, a third mode, a fourth mode, a fifth mode, a sixth mode, a seventh mode, and an eighth mode. In each of the other modes, the switching period control of the power switch tube Q1 and the freewheeling switch tube Q2 includes: the start time of the second mode is t1, and the end time is t2. After time t1, the inductor L r resonates with the parasitic capacitance C1 of the switch tube and the parasitic capacitance C2 of the freewheeling switch. The current i Lr of the energy storage inductor continues to increase in the negative direction. The voltage of the parasitic capacitance C1 starts to decrease in the positive direction from V0, and the voltage of the parasitic capacitance C2 of the freewheeling switch starts to increase in the positive direction from zero. The voltage of the parasitic capacitance C2 of the freewheeling switch increases in the positive direction to V pm , and the current i Lr of the energy storage inductor negatively increases to I n2 , and the second mode ends; the start time of the third mode is t2, and the end time is t3. The current i Lr of the energy storage inductor is freewheeled through the body diode D1 corresponding to the power switch tube Q1 to charge the input power supply V in , and the terminal voltage of the parasitic capacitance C1 of the switch tube is clamped to negative V F, at time t3, the current i of the energy storage inductor Lr decreases to equal I n1 , and the third mode ends; the start time of the fourth mode is t3 and the end time is t4. At time t3, the voltage at the C1 terminal of the parasitic capacitance of the switching transistor is clamped to negative V by the body diode D1 F , the input voltage V in charges the inductor L r in the forward direction, and the current i of the energy storage inductor Lr continues to decrease linearly in the negative direction. At time t4, the current i of the energy storage inductor Lr decreases to zero, and the fourth mode ends; the start time of the fifth mode is t4 and the end time is t5. After time t4, the input voltage V in continues to charge the inductor L r in the forward direction, and the current i of the energy storage inductor Lr increases linearly in the forward direction from zero. At time t5, the current i of the energy storage inductor Lr increases to the forward maximum value I pm , and the fifth mode ends; the start time of the sixth mode is t5 and the end time is t6. At time t5, the power switching transistor Q1 is turned off, and L r starts to resonate with the parasitic capacitance C1 of the switching transistor and the parasitic capacitance C2 of the freewheeling switch. The parasitic capacitance C1 of the switching transistor is charged, and its terminal voltage u C1 gradually increases from zero, and the parasitic capacitance C2 of the freewheeling switch discharges, and its terminal voltage u C2 gradually decreases from V0. At time t6, u C1 increases to V pm , u C2 decreases to equal negative V F , and the sixth mode ends; the start time of the seventh mode is t6 and the end time is t7. After time t6, the current i of the energy storage inductor Lr forms a freewheeling loop through the body diode D2 to supply power to the load. At time t7, the freewheeling switch transistor Q2 is turned on, and the seventh mode ends; the start time of the eighth mode is t7 and the end time is t8. After time t7, the input power supply V in supplies power to the load together with the energy storage inductor. The current i of the energy storage inductor Lr forms a freewheeling loop through the freewheeling switch transistor Q2, and the current i of the energy storage inductor Lr continues to decrease linearly in the forward direction. At time t8, i Lr decreases to zero, and the eighth mode ends.

[0017] Optionally, in the second mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switching tube, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including:

[0018] Calculating the current i Lr (t) corresponding to the energy storage inductor in the second mode according to the following formula (3), and calculating the duration Δt2 of the second mode according to the following formula (4);

[0019] The formula (3) is:

[0020]

[0021] The formula (4) is:

[0022]

[0023] Wherein,

[0024] Optionally, in the third mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switching tube, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including:

[0025] Calculating the current i Lr (t) corresponding to the energy storage inductor in the third mode according to the following formula (5), and calculating the duration Δt3 of the third mode according to the following formula (6);

[0026] The formula (5) is:

[0027]

[0028] The formula (6) is:

[0029]

[0030] Optionally, in the fourth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switching tube, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including:

[0031] Calculating the current i Lr (t) corresponding to the energy storage inductor in the fourth mode according to the following formula (7), and calculating the duration Δt4 of the fourth mode according to the following formula (8);

[0032] The formula (7) is as follows:

[0033]

[0034] The formula (8) is as follows:

[0035]

[0036] t is greater than t3 and less than or equal to t4.

[0037] Optionally, in the fifth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switching transistor, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including:

[0038] Calculate the current i Lr (t) corresponding to the energy storage inductor in the fifth mode according to the following formula (9), and calculate the duration Δt5 of the fifth mode according to the following formula (10);

[0039] The formula (9) is as follows:

[0040]

[0041] The formula (10) is as follows:

[0042]

[0043] Optionally, in the sixth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switching transistor, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including:

[0044] Calculate the current i Lr (t) corresponding to the energy storage inductor in the sixth mode according to the following formula (11), and calculate the duration Δt6 of the sixth mode according to the following formula (12);

[0045] The formula (11) is as follows:

[0046]

[0047] The formula (12) is as follows:

[0048]

[0049] Optionally, in the seventh mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitance C1 of the switching tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch, including:

[0050] Calculate the current i Lr (t) corresponding to the energy storage inductor in the seventh mode according to the following formula (13), and calculate the duration Δt7 of the seventh mode according to the following formula (14);

[0051] The formula (13) is:

[0052]

[0053] The formula (14) is:

[0054] Δt7 = t7 - t6 = nΔt6;

[0055] Wherein,

[0056] Optionally, in the eighth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitance C1 of the switching tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch, including:

[0057] Calculate the current i Lr (t) corresponding to the energy storage inductor in the eighth mode according to the following formula (15), and calculate the duration Δt8 of the eighth mode according to the following formula (16);

[0058] The formula (15) is:

[0059]

[0060] The formula (16) is:

[0061]

[0062] Wherein,

[0063] To solve the above technical problems, a technical solution adopted in an embodiment of the present application is: to provide a Boost converter, the Boost converter includes an input circuit module, a main power switch module, an energy storage and transmission module, a freewheeling circuit module, and an output filtering module. The input circuit module includes an input power supply. The main power switch module includes a power switch tube Q1, a switch tube parasitic capacitor C1, and a body diode D1. The energy storage and transmission module includes a storage inductor. The freewheeling circuit module includes a freewheeling switch tube Q2, a freewheeling switch parasitic capacitor C2, and a freewheeling body diode D2. The output filtering module includes a storage filter capacitor EC2 and a load resistor R L , the positive pole of the input power supply is connected to one end of the storage inductor, the other end of the storage inductor is connected between the drain of the power switch tube Q1 and the source of the freewheeling switch tube Q2, the source of the power switch tube Q1 is respectively connected to the negative pole of the input power supply and one end of the output filtering module, the drain of the freewheeling switch tube Q2 is connected to the other end of the output filtering module, the storage filter capacitor EC2 and the load resistor R L are connected in parallel to smooth the output voltage and supply it to the load. The Boost converter further includes a control module, the control module is used to connect the gates of the power switch tube Q1 and the freewheeling switch tube Q2, and the control module is used to: calculate the duration of each mode and the current corresponding to the storage inductor according to the state of the current of the storage inductor, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2 in the first mode. Wherein, in the first mode, the states of the power switch tube Q1 and the freewheeling switch tube Q2 are initialization states; generate a control signal according to the duration of each mode and the current corresponding to the storage inductor; monitor the current i Lr corresponding to the storage inductor; when it is monitored that the current i Lr corresponding to the storage inductor reaches a preset first current value I n1 , control the Boost converter to sequentially switch from the first mode to other modes according to the control signal to realize soft-switching control of the Boost converter; wherein, the first current value I n1 satisfies a first preset condition, and the first preset condition is set according to the terminal voltage of the storage filter capacitor EC2, the switch tube parasitic capacitor C1, and the storage inductor.

[0064] The soft-switching control method and the Boost converter provided by the embodiments of the present application enable the control module to dynamically adjust the switching mode according to the state of the current of the storage inductor and the characteristics of the switch tube parasitic capacitor C1 and the freewheeling switch parasitic capacitor C2 in the first mode, so as to optimize the switching process and ensure switching operation at near zero voltage. In addition, based on the current i LrBased on the real-time status of the parasitic capacitance, the control module can accurately calculate the duration of each mode. This precise timing control can optimize the switching process and reduce switching losses. According to the calculated duration and current value of each mode, the control module generates corresponding control signals, which are used to precisely control the switching behavior of the power switch and the freewheeling switch, ensuring turn-on under zero-voltage conditions and reducing switching losses. Moreover, the set first current value meets specific preset conditions, which are set based on the voltage of the energy storage filter capacitor, the parasitic capacitance, and the energy storage inductor, enabling the system to maintain soft-switching operation under different input conditions. This adaptability allows the Buck converter to break through the sampling rate limitations of traditional MCUs, operate stably in a wider working environment, achieve a higher switching frequency, and thus the system can respond and process input signals faster, improving the real-time performance and accuracy of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] To more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0066] Figure 1 is a circuit diagram of a Boost converter provided by an embodiment of the present application;

[0067] Figure 2 is a flowchart of a soft-switching control method provided by an embodiment of the present application;

[0068] Figure 3 is a working waveform diagram corresponding to the Boost converter executing the soft-switching control method provided by an embodiment of the present application;

[0069] Figures 4a to 4h are respectively schematic diagrams of the circuit modes corresponding to the operation of eight modes (i.e., the first mode to the eighth mode) provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0070] In order to make the objectives, technical solutions, and advantages of the present application clearer, the following further details the present application in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0071] It should be noted that if there is no conflict, the various features in the embodiments of the present application can be combined with each other, and all are within the protection scope of the present application. In addition, although functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order from the module division in the device or the flowchart. Furthermore, the terms "first", "second", "third", etc. adopted in the present application do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0072] Due to its simple structure, low cost, easy control and high reliability, the Boost circuit topology has become the most commonly used topology in non-isolated DC / DC boost converters and is widely used in fields such as photovoltaic power generation, hybrid vehicles and energy storage systems. To meet the requirements of engineering applications for high power, high efficiency, high integration, small volume and light weight, increasing the switching frequency is the most direct method. However, a higher switching frequency also brings greater switching losses and more serious electromagnetic interference problems.

[0073] For this reason, soft-switching technology has emerged, which can effectively reduce switching losses and electromagnetic interference while increasing the switching frequency. Traditional soft-switching technology usually realizes zero-voltage or zero-current switching of high-frequency switching tubes by introducing an auxiliary network. Although this method improves the switching performance, the additional auxiliary network circuit also brings some problems, such as increasing the complexity, cost and volume of the circuit. Therefore, soft-switching technology without an auxiliary network has gradually become a research hotspot, and with the advantages of low cost, small volume, high stability and easy implementation, it has become an important direction for the development of soft-switching technology.

[0074] In soft-switching technology without an auxiliary network, BCM (Boundary Conduction Mode) control and TCM (Transition Conduction Mode) control are the most commonly used implementation methods. This method controls the reverse current of the inductor to make the inductor resonate with the parasitic capacitance of the switching tube, thereby realizing soft-switching actions and reducing switching losses. Currently, Boost converters using BCM or TCM control usually adopt a variable-frequency control strategy, that is: operating at a high switching frequency under light load to optimize the soft-switching effect; operating at a low switching frequency under heavy load to reduce losses and stress.

[0075] Although the Boost converter based on BCM or TCM control can achieve soft-switching within a certain range, there are still some problems in its actual application, mainly including the problem that zero-voltage turn-on is difficult to cover the full range and the switching frequency is limited.

[0076] Among them, for a Boost converter adopting the traditional BCM control strategy, due to the relatively large output parasitic capacitance of the high-power MOS transistor, it is difficult for the Boost transistor to achieve zero-voltage turn-on within the full voltage and full power range in the scenarios of wide input voltage and wide power variation; especially under high-frequency operating conditions, the charging and discharging time of the parasitic capacitance is insufficient, resulting in the switching transistor being unable to maintain zero-voltage state turn-on, increasing the switching loss and electromagnetic interference.

[0077] Among them, for a Boost converter adopting the TCM control strategy, in order to achieve variable-frequency control, it usually relies on the sampling rate of the MCU to achieve peak current detection. However, limited by the processing power of the existing MCU, the sampling rate is difficult to support high-frequency (such as exceeding 150 kHz) operation, which restricts the increase of the switching frequency, thus affecting the soft-switching performance and variable-frequency range of the converter under wide voltage input conditions and making it difficult to meet the engineering requirements for high-efficiency and high-frequency operation.

[0078] Therefore, the current soft-switching control strategies have problems of limited zero-voltage turn-on range and difficulty in breaking through the sampling rate limitation of the existing MCU for the switching frequency.

[0079] To solve the above problems, the embodiment of the present application provides a soft-switching control method. This method divides the PWM period into multiple precisely controlled modes. Through the real-time detection and control of the inductor current and voltage states, seamless connection of each mode is achieved; through the resonance process between modes, natural charging and discharging of the parasitic capacitance of the switching transistor are completed, thereby realizing zero-voltage switching.

[0080] This method monitors the current i corresponding to the energy storage inductor Lr and calculates the duration and current change in the mode, and can accurately adjust the duration and current of each working mode according to dynamic parameters such as input voltage and parasitic capacitance, ensuring that zero-voltage switching can be achieved even within a wide input voltage and output power range, thus overcoming the limitations of the traditional control strategy.

[0081] By pre-calculating the duration of each mode and the inductor current, and using these pre-calculation results to generate control signals, it no longer relies on the real-time sampling of the MCU, avoiding the problem that high-frequency soft-switching control cannot be achieved due to the sampling rate limitation.

[0082] The control module can also calculate the duration of each mode according to the state of the real-time current and parasitic capacitance, and sequentially switch the working modes, which provides an accurate switching control signal for the Boost converter, ensuring its efficient operation and improving the overall control accuracy.

[0083] Therefore, this soft-switching control method realizes high-frequency, wide-range, and high-efficiency soft-switching control as a whole, breaks through the limitations of the traditional method, and can meet the application requirements of higher frequency and higher efficiency.

[0084] The soft-switching control method provided by the embodiments of the present application will be described below through specific embodiments.

[0085] Refer to Figure 1 , Figure 1 , which is a circuit diagram of a Boost converter provided by the embodiments of the present application. The Boost converter includes an input circuit module, a main power switch module, an energy storage and transfer module, a freewheeling loop module, and an output filter module. Among them, the input circuit module includes an input power supply V in , the main power switch module includes a power switch tube Q1, a switch tube parasitic capacitor C1, and a body diode D1, the energy storage and transfer module includes an energy storage inductor L r , the freewheeling loop module includes a freewheeling switch tube Q2, a freewheeling switch parasitic capacitor C2, and a freewheeling body diode D2, and the output filter module includes an energy storage filter capacitor EC2 and a load resistor R L . Among them, the positive pole of the input power supply is connected to one end of the energy storage inductor, and the other end of the energy storage inductor is connected between the drain of the power switch tube Q1 and the source of the freewheeling switch tube Q2. The source of the power switch tube Q1 is respectively connected to the negative pole of the input power supply and one end of the output filter module. The drain of the freewheeling switch tube Q2 is connected to the other end of the output filter module. The energy storage filter capacitor EC2 and the load resistor R L are connected in parallel to smooth the output voltage and supply it to the load. Among them, Figure 1 the arrow in points to the reference positive direction of the physical quantity.

[0086] This Boost converter is a step-up DC-DC converter, and its working principle is based on the characteristics of energy storage and release of the inductor. Its working process mainly includes the following stages: First, the switch conduction stage. When the power switch tube Q1 conducts, the voltage of the input power supply is applied to the energy storage inductor through Q1, and the energy storage inductor L r starts to charge and store energy, and the current gradually increases. At the same time, the energy storage filter capacitor EC2 will supply power to the load resistor R L . Then, the switch off stage. When Q1 is turned off, the current in the energy storage inductor L r does not immediately interrupt, forming a freewheeling current; the freewheeling switch tube Q2 conducts, and the current in the energy storage inductor L r flows through Q2 to the output filter module; the energy storage inductor releases the stored energy to increase the output voltage to continue to supply power to the load. Finally, the output smoothing stage. The energy storage filter capacitor EC2 smooths the output voltage to reduce fluctuations so that the load obtains a stable voltage.

[0087] In the embodiment of the present application, the Boost converter further includes a control module, which is used to connect the gates of the power switch Q1 and the freewheeling switch Q2. The control module realizes precise regulation of the states of the power switch Q1 and the freewheeling switch Q2, ensuring that the energy conversion process is more efficient and stable. The control module is used to execute the soft-switching control method of the embodiment of the present application. This method divides each PWM cycle into multiple precisely controlled modes. Through the real-time detection of the current and voltage states of the energy storage inductor and the resonance process between the modes, the natural charging and discharging of the parasitic capacitance of the switch tube are realized, so as to achieve the effect of zero-voltage switching.

[0088] Specifically, referring to Figure 2 , Figure 2 is a flowchart of a soft-switching control method provided by an embodiment of the present application.

[0089] S11. The control module calculates the duration of each mode and the current corresponding to the energy storage inductor respectively according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitance C1 of the switch tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch. Among them, in the first mode, the states of the power switch Q1 and the freewheeling switch Q2 are in the initialization state.

[0090] S12. Generate a control signal according to the duration of each mode and the current corresponding to the energy storage inductor.

[0091] S13. Monitor the current i corresponding to the energy storage inductor Lr .

[0092] S14. When it is monitored that the current i corresponding to the energy storage inductor Lr reaches the preset first current value I n1 , the control module controls the Boost converter to sequentially switch from the first mode to other modes according to the control signal to realize the soft-switching control of the Boost converter; among them, the first current value I n1 satisfies the first preset condition, and the first preset condition is set according to the terminal voltage of the energy storage filter capacitor EC2, the parasitic capacitance C1 of the switch tube, and the energy storage inductor.

[0093] Referring to Figure 3 , the first mode is the time period from t0 to t1. The start time of the first mode is t0, and the end time is t1. In the first mode, the switching period control of the power switch Q1 and the freewheeling switch Q2 includes: at time t0, i Lr decreases to zero, and the difference between the terminal voltage V0 of the output energy storage filter capacitor EC2 and the input voltage V of the input power supply in reversely charges the energy storage inductor, and i Lr starts to increase linearly in the negative direction. At time t1, i Lr negatively increases to the preset first current value In1 At this time, the freewheeling switch tube Q2 is turned off to complete the first mode. Before time t0, the power switch tube Q1 is in the off state, and the freewheeling switch tube Q2 is in the on state. The freewheeling switch tube Q2 provides a freewheeling path for the energy storage inductor, and the current i corresponding to the energy storage inductor Lr decreases linearly in the positive direction.

[0094] This first mode realizes the reverse charging and energy recovery of the energy storage inductor, ensuring that the system can maintain effective energy management while increasing the output voltage.

[0095] The above step S13 monitors the current i corresponding to the energy storage inductor in real time Lr , aiming to obtain the current value of i Lr for triggering mode switching or judging whether the control conditions are met. This monitoring process is real-time and runs through the entire control process.

[0096] The above steps S11 and S12 can be pre-calculated and generated parts. According to the state of the current of the energy storage inductor in the first mode and the real-time states of the parasitic capacitors C1 and C2, the control module can calculate the duration of each mode and the current of the energy storage inductor in each mode. The current of the energy storage inductor in each mode changes dynamically with time. According to the control logic of the inverter, the duration and current of the mode determine the switching timing and energy transfer efficiency. These calculations can be completed through preset parameters before the system runs and adjusted dynamically during operation. Based on the calculation results of step S11, specific control signals are generated to drive the power switch tube Q1 and the freewheeling switch tube Q2. The above step S11 can be completed during system initialization as initialization data, and step S12 can be performed during real-time application to adapt to the dynamic changes of the circuit state.

[0097] Among them, in the first mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor respectively according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switch tube, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including:

[0098] Calculate the current i corresponding to the energy storage inductor in the first mode according to the following formula (1) Lr (t), and calculate the duration Δt1 of the first mode according to the following formula (2);

[0099] Formula (1) is:

[0100]

[0101] Formula (2) is:

[0102]

[0103] Among them, L r is the inductance value corresponding to the energy storage inductor. I n1 is the current value corresponding to the energy storage inductor, which satisfies the first preset condition. The first preset condition can be determined according to the following formula:

[0104]

[0105] Among them, V o is the terminal voltage of the energy storage filter capacitor EC2, C oss is the capacitance value of the parasitic capacitor C1 of the switching tube, L r is the inductance value corresponding to the energy storage inductor.

[0106] When the current of the energy storage inductor is the above I n1 , mode switching is performed. The above conditions the I n1 to ensure that the voltage or current on the parasitic capacitor reaches an appropriate level, thereby reducing switching losses and electromagnetic interference. I n1 is directly related to the voltage V o and parasitic parameters. Such a setting ensures that the system can dynamically adapt to changes in the voltage of the energy storage filter capacitor and circuit parameters, and avoids the operating state deviating from the design target. Moreover, the current condition limitation ensures that the circuit state meets the design requirements during mode switching, avoids system oscillation or instability caused by discontinuous changes in current or voltage, and the preset condition of the current is based on the system design parameters and can dynamically adapt to load changes, thereby improving the stability of the system in different working environments. Therefore, the setting of the above first preset condition reduces switching losses, reduces overshoot and harmonic interference, improves system reliability, and realizes stable operation in a dynamic environment.

[0107] See Figure 4a , Figure 4a is the equivalent circuit corresponding to the above first mode, where the arrow indicates the actual flow direction of the current during the operation of the inverter. In addition to the above first mode, the embodiments of the present application also provide other modes, and the other modes include a second mode, a third mode, a fourth mode, a fifth mode, a sixth mode, a seventh mode, and an eighth mode, respectively corresponding to Figures 4b to 4h , where the arrow indicates the actual flow direction of the current during the operation of the inverter.

[0108] See Figure 3 and Figure 4b , the second mode is from t1 to t2. The start time of the second mode is t1, and the end time is t2. After t1, the inductor L r starts to resonate with the parasitic capacitor C1 of the switching tube and the parasitic capacitor C2 of the freewheeling switch. The current i LrContinue to increase negatively, the voltage of the parasitic capacitor C1 starts to decrease positively from V0, the voltage of the freewheeling switch parasitic capacitor C2 starts to increase positively from zero, and the voltage of the freewheeling switch parasitic capacitor C2 increases positively to V pm , the current i of the energy storage inductor Lr decreases negatively to I n2 , and the second mode ends. In the second mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the switch parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: calculating the current i corresponding to the energy storage inductor in the second mode according to the following formula (3) Lr (t), and calculating the duration Δt2 of the second mode according to the following formula.

[0109] Formula (3) is:[[]]

[0110]

[0111] Formula (4) is:[[]]

[0112]

[0113] Wherein,[[]]

[0114] Wherein, at time t2, the negative current of the energy storage inductor is I n2 , and its corresponding calculation formula is:[[]]

[0115]

[0116] At time t2, u c2 The positive maximum voltage V pm is: V pm = V0 + V F .

[0117] Wherein, the duration of t1 - t2 is mainly determined by the conduction voltage of the driving power switch Q1 and its corresponding body diode. The voltage on the parasitic capacitor of the driving power switch Q1 is -V F , at this time the body diode of the driving power switch Q1 conducts, and V F is the voltage required for the body diode to conduct.

[0118] Wherein, in the second mode, the voltages of C1 and C2 are calculated according to the following formula:[[]]

[0119]

[0120] The above second mode completes the resonance of the energy storage inductor current and the parasitic capacitor voltage u through the resonance of the energy storage inductor, the switch parasitic capacitor C1, and the freewheeling switch parasitic capacitor C2C1 , u C2 The adjustment of [u] lays the foundation for the smooth switching of subsequent modes and soft-switching control. In this second mode, zero-voltage switching is achieved, reducing switching losses; the second mode utilizes the resonance mechanism to efficiently transfer energy between the energy storage inductor and the parasitic capacitance, reducing the waste of inductor energy and maximizing the energy utilization rate; during the mode switching process, the resonance is used to achieve smooth changes in current and voltage, avoiding the impact of high voltage and high current on the devices.

[0121] See Figure 3 and Figure 4c , the third mode is from t2 to t3. The start time of the third mode is t2, and the end time is t3. After t2, the current i of the energy storage inductor Lr flows through the body diode D1 corresponding to the power switch Q1 to charge the input power supply V in , and the voltage at the parasitic capacitance C1 of the switch tube is clamped to -V by the body diode D1 F . At t3, the current i of the energy storage inductor Lr decreases to equal I n1 , and the third mode ends.

[0122] In the third mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor, the real-time state of the parasitic capacitance C1 of the switch tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch in the first mode, including: calculating the current i corresponding to the energy storage inductor in the third mode according to the following formula (5) Lr (t), and calculating the duration Δt3 of the third mode according to the following formula (6);

[0123] Formula (5) is:

[0124]

[0125] Formula (6) is:

[0126]

[0127] In the third mode, through the discharge of the parasitic capacitance C2 of the freewheeling switch and the reverse charging of the energy storage inductor, the inductor current i Lr and the related voltage are gradually adjusted to provide support for subsequent operations and the stable operation of the system. Through this third mode, through the energy transfer and clamping of the energy storage inductor and the parasitic capacitance, an ideal current and voltage state are established for subsequent operations, and at the same time, efficient soft-switching control is achieved.

[0128] See Figure 3 and Figure 4d, the fourth mode is from t3 to t4. The start time of the fourth mode is t3, and the end time is t4. At t3, the voltage at the C1 terminal of the switch parasitic capacitor is clamped to -V by the body diode D1 F , the input voltage V in charges the inductor L r in the forward direction. The current i of the energy storage inductor Lr continues to decrease linearly in the negative direction. At t4, the current i of the energy storage inductor Lr decreases to zero, and the fourth mode ends. In the fourth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor, the real-time state of the switch parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2 in the first mode, including: calculating the current i Lr (t) corresponding to the energy storage inductor in the fourth mode according to the following formula (7), and calculating the duration Δt4 of the fourth mode according to the following formula (8);

[0129] Formula (7) is:

[0130]

[0131] Formula (8) is:

[0132]

[0133] The fourth mode is the energy transfer and regulation stage. It mainly provides an ideal starting point for the next stage of energy control by charging the energy storage inductor in the forward direction and regulating the state of the parasitic capacitor. In this fourth mode, the forward reduction of the energy storage inductor current is achieved, so that the current of the energy storage inductor meets the initial conditions of the next mode, and at the same time, partial release or storage of the energy of the energy storage inductor is realized. The voltage of the switch parasitic capacitor C1 is clamped to -V F , realizing the zero-voltage turn-off condition of the driving power switch Q1, thereby reducing the power loss during the switching process. The input voltage V in charges the inductor L r in the forward direction, regulates the energy distribution of the system, ensures that the system energy is reasonably distributed in each stage, and avoids the situation of energy surplus or deficiency. At t4, the current i of the energy storage inductor Lr decreases to zero, providing a stable current initial condition for the next mode switching. This process can achieve smooth mode switching and reduce system oscillation caused by current mutation.

[0134] See Figure 3 and Figure 4e , the fifth mode is from t4 to t5. The start time of the fifth mode is t4, and the end time is t5. After t4, the input voltage V in continues to charge the inductor L rForward charging, current i of the energy storage inductor Lr Increases linearly in the positive direction from zero. At time t5, the current i of the energy storage inductor Lr Increases to the positive maximum value I pm , and the fifth mode ends. In the fifth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode r , the real-time state of the parasitic capacitance C1 of the switching tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch, including: calculating the current i corresponding to the energy storage inductor in the fifth mode according to the following formula (9) Lr (t), and calculating the duration Δt5 of the fifth mode according to the following formula (10);

[0135] Formula (9) is:[[]]

[0136]

[0137] Formula (10) is:[[]]

[0138]

[0139] The fifth mode mainly replenishes energy for the energy storage inductor, making its current increase linearly in the positive direction from zero, providing ideal conditions for the switching of subsequent modes. This fifth mode realizes a smooth transition from the zero-current state to the maximum positive current state, improving the dynamic performance of the system.

[0140] See Figure 3 and Figure 4f , the sixth mode is from time t5 to t6. The start time of the sixth mode is t5, and the end time is t6. At time t5, the power switch Q1 is turned off, and L r Resonates with the parasitic capacitance C1 of the switching tube and the parasitic capacitance C2 of the freewheeling switch. The parasitic capacitance C1 of the switching tube is charged, and its terminal voltage u C1 Gradually increases from zero, and the parasitic capacitance C2 of the freewheeling switch discharges, and its terminal voltage u C2 Gradually decreases from V0. At time t6, u C1 Increases to V pm , u C2 Decreases to equal negative V F , and the sixth mode ends. In the sixth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitance C1 of the switching tube, and the real-time state of the parasitic capacitance C2 of the freewheeling switch, including: calculating the current i corresponding to the energy storage inductor in the sixth mode according to the following formula (11) Lr (t), and calculating the duration Δt6 of the sixth mode according to the following formula (12);

[0141] Equation (11) is as follows:

[0142]

[0143] Equation (12) is as follows:

[0144]

[0145] In the sixth mode, the voltages of C1 and C2 are calculated according to the following formula:

[0146]

[0147]

[0148] where, at time t6, the negative current of the energy storage inductor is I p1 , and its corresponding calculation formula is as follows:

[0149]

[0150] where,

[0151] In the sixth mode, the resonance dynamics of the energy storage inductor, the parasitic capacitance C1 of the switching transistor, and the parasitic capacitance C2 of the freewheeling switch ensure the soft-switching condition of the power switch, and at the same time provide a starting point for the energy management of the next cycle. Among them, the parasitic capacitance C1 of the switching transistor and the parasitic capacitance C2 of the freewheeling switch complete the voltage adjustment through resonance with the energy storage inductor, adjust the voltage of the parasitic capacitance, and create conditions for realizing the zero-voltage switching operation of the power switching transistor. Then, the resonance dynamics between the energy storage inductor and the parasitic capacitance cause the current of the energy storage inductor to linearly change negatively from the positive maximum value I pm and finally reach I p1 , which provides the necessary initial conditions for the mode switching of the next cycle. At time t6, u C1 increases to V pm , u C2 decreases to equal negative V F , at this time, the body diodes of the power switching transistor and the freewheeling switch are turned on, which reduces the on and off losses during the switching process and improves the efficiency of the switching device. During the resonance dynamic process corresponding to this mode, the energy exchange between the energy storage inductor and the parasitic capacitance realizes the optimal distribution of the system energy.

[0152] See Figure 3 and Figure 4g , the seventh mode is from t6 to t7. The start time of the seventh mode is t6, and the end time is t7. After time t6, the current i LrThe body diode D2 forms a freewheeling loop to supply power to the load. At time t7, the freewheeling switch Q2 is turned on, and the seventh mode ends. In the seventh mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitance C1 of the switch, and the real-time state of the parasitic capacitance C2 of the freewheeling switch, including: calculating the current i Lr (t) corresponding to the energy storage inductor in the seventh mode according to the following formula (13), and calculating the duration Δt7 of the seventh mode according to the following formula (14);

[0153] Formula (13) is:

[0154]

[0155] Formula (14) is:

[0156] Δt7 = t7 - t6 = nΔt6;

[0157]

[0158] Among them, at time t7, the negative current of the energy storage inductor is I p2 , and its corresponding calculation formula is:

[0159]

[0160] Among them, n is a constant, and the value of n can be set according to actual needs.

[0161] The seventh mode is an important stage for the energy storage inductor to form a freewheeling loop through the body diode to supply power to the load. In this mode, the current of the energy storage inductor gradually decreases, providing ideal conditions for the turn-on of the freewheeling switch Q2. This mode improves the continuity and reliability of the load power supply, especially when the load changes dynamically; it also reduces the switching loss, reduces the heat generation of the switching device, extends the service life of the switching device, provides a smooth mode switch, and enhances the system adaptability.

[0162] See Figure 3 and Figure 4h , the eighth mode is from t7 to t8. The start time of the eighth mode is t7, and the end time is t8. After time t7, the input power supply V in and the energy storage inductor supply power to the load together. The current i Lr of the energy storage inductor forms a freewheeling loop through the freewheeling switch Q2. The current i Lr of the energy storage inductor continues to linearly decrease in the positive direction. At time t8, i LrReduce to zero, and the eighth mode ends. In the eighth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor respectively according to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switching tube, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, including: calculating the current i Lr (t) corresponding to the energy storage inductor in the eighth mode according to the following formula (15), and calculating the duration Δt8 of the eighth mode according to the following formula (16);

[0163] Formula (15) is:

[0164]

[0165] Formula (16) is:

[0166]

[0167] where, I p2 is the negative current of the energy storage inductor,

[0168] The eighth mode realizes continuous power supply to the load through the current decay process of the energy storage inductor, and at the same time lays a foundation for the reset and stable operation of the circuit mode. The end of the eighth mode marks the end of a complete control PWM control cycle, provides an ideal initial condition for entering a new cycle, and plays a key role in the efficient and stable operation of the system.

[0169] The division of the above eight working modes can achieve precise control of the inductor current and the charging and discharging processes of the parasitic capacitors of the switching tubes, ensuring zero-voltage switching at specific moments. In some embodiments, the mode division can also be reduced or increased, and the specific division can be flexibly adjusted according to actual application requirements.

[0170] The soft-switching control method provided by the embodiments of the present application firstly realizes a wider zero-voltage switching. By setting the initial negative resonant current of the inductor, the energy stored in the resonant inductor is precisely controlled, enabling the Boost transistor to achieve ideal zero-voltage switching under a wider range of input voltages and output voltages, a larger range of output powers, and higher MOS transistor output parasitic capacitance conditions. Moreover, the control accuracy and switching frequency are improved. Among the eight operating modes of the Boost converter, the duration of each mode and the inductor current can be accurately calculated based on relevant parameters, thereby accurately calculating the switching period. This advantage enables the MCU to be no longer limited by the sampling rate and supports higher-frequency soft-switching control. For example, when specifically applied to a Boost converter product with an output of 500W, its highest switching frequency reaches 300kHz, demonstrating excellent control performance. Finally, the conversion efficiency is improved. By implementing the control strategy proposed in this embodiment in a 500W-output Boost converter, the conversion efficiency of this converter under full-load conditions reaches 97.6%. Compared with a Boost converter operating in the traditional fixed-frequency CCM mode, the full-load conversion efficiency is increased by nearly 2%, significantly optimizing the energy utilization rate of the system.

[0171] The Boost converter provided by the embodiments of the present application can be used to execute the above soft-switching control method. By precisely controlling the dynamic process of the inductor current and the parasitic capacitance of the switching transistor, high-frequency soft-switching operation is achieved on the premise of ensuring efficiency and stability, and it has the same beneficial effects as the embodiments of the soft-switching control method. Through the above soft-switching control method, the Boost converter can operate efficiently and stably under complex working conditions, and is particularly suitable for application scenarios with wide input and output ranges and high power density. It shows significant advantages in aspects such as energy utilization, control accuracy, and system reliability, and has important practical value.

[0172] The above-disclosed are only the preferred embodiments of the present application. Of course, the scope of the rights of the present application cannot be limited thereby. Therefore, equivalent changes made according to the claims of the present application still fall within the scope covered by the present application.

Claims

1. A soft switch control method, applied to a Boost converter, wherein the Boost converter comprises an input circuit module, a main power switch module, an energy storage and transmission module, a freewheeling loop module and an output filter module, wherein the input circuit module comprises an input power supply, the main power switch module comprises a power switch tube Q1, a switch tube parasitic capacitor C1 and a body diode D1, the energy storage and transmission module comprises an energy storage inductor, the freewheeling loop module comprises a freewheeling switch tube Q2, a freewheeling switch parasitic capacitor C2 and a freewheeling body diode D2, the output filter module comprises an energy storage filter capacitor EC2 and a load resistor R L The positive electrode of the input power supply is connected to one end of the energy storage inductor, and the other end of the energy storage inductor is connected between the drain of the power switch tube Q1 and the source of the freewheeling switch tube Q2. The source of the power switch tube Q1 is respectively connected to the negative electrode of the input power supply and one end of the output filter module, and the drain of the freewheeling switch tube Q2 is connected to the other end of the output filter module. The energy storage filter capacitor EC2 and the load resistor R L Connected in parallel to smooth the output voltage and provide it to the load. It is characterized in that The Boost converter further includes a control module, and the control module is used to connect the gates of the power switch tube Q1 and the freewheeling switch tube Q2. The method includes: The control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor, the real-time state of the switch tube parasitic capacitor C1 and the real-time state of the freewheeling switch parasitic capacitor C2 in the first mode, wherein in the first mode, the states of the power switch tube Q1 and the freewheeling switch tube Q2 are in the initialization state; generating a control signal according to the duration of each mode and the current corresponding to the energy storage inductor; Monitor the current i corresponding to the energy storage inductor Lr ; When the current i corresponding to the energy storage inductor is monitored Lr Reaching the preset first current value I n1 , the control module controls the Boost converter to switch from the first mode to other modes in sequence according to the control signal to achieve soft switching control of the Boost converter; wherein the first current value I n1 A first preset condition is met, and the first preset condition is set according to the terminal voltage of the energy storage filter capacitor EC2, the parasitic capacitance C1 of the switch tube, and the energy storage inductor.

2. The method according to claim 1, characterized in that The first current value I n1 The first preset condition is satisfied, and the first preset condition is set according to the terminal voltage of the energy storage filter capacitor EC2, the parasitic capacitance C1 of the switch tube, and the energy storage inductor, including: The first preset condition is determined according to the following formula: Among them, V o is the terminal voltage of the energy storage filter capacitor EC2, C oss is the capacitance value of the parasitic capacitance C1 of the switch tube, L r is the inductance value corresponding to the energy storage inductor.

3. The method according to claim 1, characterized in that: The first mode starts at t0 and ends at t1. In the first mode, the switching cycle control of the power switch tube Q1 and the freewheeling switch tube Q2 includes: At time t0, i Lr The terminal voltage V0 of the output energy storage filter capacitor EC2 is equal to the input voltage V in The difference between the two reverse charges the energy storage inductor, i Lr It starts to increase linearly in a negative direction. At time t1, i Lr The negative current increases to the preset first current value I n1 When the freewheeling switch tube Q2 is turned off.

4. The method according to claim 3, characterized in that In the first mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor, the real-time state of the switch tube parasitic capacitor C1 and the real-time state of the freewheeling switch parasitic capacitor C2 in the first mode, including: The current i corresponding to the energy storage inductor in the first mode is calculated according to the following formula (1): Lr (t), and calculate the duration Δt1 of the first mode according to the following formula (2); The formula (1) is: The formula (2) is: Among them, L r is the inductance value corresponding to the energy storage inductor.

5. The method according to claim 1, characterized in that The other modes include a second mode, a third mode, a fourth mode, a fifth mode, a sixth mode, a seventh mode and an eighth mode. In each of the other modes, the switching cycle control of the power switch tube Q1 and the freewheeling switch tube Q2 includes: The second mode starts at t1 and ends at t2. After t1, the inductor L r It starts to resonate with the parasitic capacitance C1 of the switch tube and the parasitic capacitance C2 of the freewheeling switch, and the current i Lr Continue to increase negatively, the voltage of parasitic capacitor C1 decreases positively from V0, the voltage of parasitic capacitor C2 of freewheeling switch increases positively from zero, and the voltage of parasitic capacitor C2 of freewheeling switch increases positively to V pm , the current i of the energy storage inductor Lr Negative increase to I n2 , the second mode ends; The start time of the third mode is t2, and the end time is t3. After t2, the current i Lr The body diode D1 corresponding to the power switch tube Q1 is used to continue the current to the input power supply V in The voltage at the parasitic capacitor C1 of the switch tube is clamped to the negative V by the body diode D1. F At time t3, the current i of the energy storage inductor is Lr Reduce to equal I n1 , the third mode ends; The fourth mode starts at time t3 and ends at time t4. At time t3, the voltage at the terminal of the parasitic capacitor C1 of the switch tube is clamped to a negative voltage V by the body diode D1. F , input voltage V in Give inductor L r Forward charging, the current i of the energy storage inductor Lr Continue to decrease linearly in the negative direction. At time t4, the current i Lr Decreases to zero, and the fourth mode ends; The fifth mode starts at time t4 and ends at time t5. After time t4, the input voltage V in Continue to give the inductor L r Forward charging, the current i of the energy storage inductor Lr It starts from zero and increases linearly in a positive direction. At time t5, the current i Lr Increase to the positive maximum value I pm , the fifth mode ends; The start time of the sixth mode is t5, and the end time is t6. At t5, the power switch tube Q1 is turned off, and L r It starts to resonate with the parasitic capacitance C1 of the switch tube and the parasitic capacitance C2 of the freewheeling switch. The parasitic capacitance C1 of the switch tube is charged, and its terminal voltage u C1 Starting from zero, it gradually increases, and the parasitic capacitance C2 of the freewheeling switch discharges, and its terminal voltage u C2 Starting from V0, it gradually decreases. At t6, u C1 Increase to V pm ,u C2 decreases to equal negative V F , the sixth mode ends; The start time of the seventh mode is t6, and the end time is t7. After t6, the current i Lr The body diode D2 forms a freewheeling loop to supply power to the load. At time t7, the freewheeling switch Q2 is turned on, and the seventh mode ends. The eighth mode starts at time t7 and ends at time t8. After time t7, the input power V in Together with the energy storage inductor, the current i of the energy storage inductor is Lr The freewheeling switch tube Q2 forms a freewheeling loop, and the current i Lr Continue to decrease linearly in the positive direction. At time t8, i Lr Decreases to zero and the eighth mode ends.

6. The method according to claim 5, characterized in that In the second mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the second mode is calculated according to the following formula (3): Lr (t), and calculate the duration Δt2 of the second mode according to the following formula (4); The formula (3) is: The formula (4) is: in, 7. The method according to claim 5, characterized in that In the third mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the third mode is calculated according to the following formula (5): Lr (t), and calculate the duration Δt3 of the third mode according to the following formula (6); The formula (5) is: The formula (6) is:

8. The method according to claim 5, characterized in that In the fourth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the fourth mode is calculated according to the following formula (7): Lr (t), and calculate the duration Δt4 of the fourth mode according to the following formula (8); The formula (7) is: t is greater than t3 and less than or equal to t4.

9. The method according to claim 5, characterized in that In the fifth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the fifth mode is calculated according to the following formula (9): Lr (t), and calculate the duration Δt5 of the fifth mode according to the following formula (10); The formula (9) is: The formula (10) is:

10. The method according to claim 5, characterized in that In the sixth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the current state of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the sixth mode is calculated according to the following formula (11): Lr (t), and calculate the duration Δt6 of the sixth mode according to the following formula (12); The formula (11) is: The formula (12) is:

11. The method according to claim 5, characterized in that In the seventh mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the seventh mode is calculated according to the following formula (13): Lr (t), and calculate the duration Δt7 of the seventh mode according to the following formula (14); The formula (13) is: The formula (14) is: Δt7=t7-t6=nΔt6; in, 12. The method according to claim 11, characterized in that In the eighth mode, the control module calculates the duration of each mode and the current corresponding to the energy storage inductor according to the state of the current of the energy storage inductor in the first mode, the real-time state of the switch tube parasitic capacitor C1, and the real-time state of the freewheeling switch parasitic capacitor C2, including: The current i corresponding to the energy storage inductor in the eighth mode is calculated according to the following formula (15): Lr (t), and the duration Δt8 of the eighth mode is calculated according to the following formula (16); The formula (15) is: The formula (16) is: in, 13. A Boost converter, the Boost converter comprising an input circuit module, a main power switch module, an energy storage and transmission module, a freewheeling loop module and an output filter module, the input circuit module comprising an input power supply, the main power switch module comprising a power switch tube Q1, a switch tube parasitic capacitor C1 and a body diode D1, the energy storage and transmission module comprising an energy storage inductor, the freewheeling loop module comprising a freewheeling switch tube Q2, a freewheeling switch parasitic capacitor C2 and a freewheeling body diode D2, the output filter module comprising an energy storage filter capacitor EC2 and a load resistor R L The positive electrode of the input power supply is connected to one end of the energy storage inductor, and the other end of the energy storage inductor is connected between the drain of the power switch tube Q1 and the source of the freewheeling switch tube Q2. The source of the power switch tube Q1 is respectively connected to the negative electrode of the input power supply and one end of the output filter module, and the drain of the freewheeling switch tube Q2 is connected to the other end of the output filter module. The energy storage filter capacitor EC2 and the load resistor R L Connected in parallel to smooth the output voltage and provide it to the load. It is characterized in that The Boost converter further includes a control module, which is used to connect the gates of the power switch tube Q1 and the freewheeling switch tube Q2, and is used to: According to the state of the current of the energy storage inductor in the first mode, the real-time state of the parasitic capacitor C1 of the switch tube, and the real-time state of the parasitic capacitor C2 of the freewheeling switch, respectively calculate the duration of each mode and the current corresponding to the energy storage inductor, wherein in the first mode, the states of the power switch tube Q1 and the freewheeling switch tube Q2 are in the initialization state; generating a control signal according to the duration of each mode and the current corresponding to the energy storage inductor; Monitor the current i corresponding to the energy storage inductor Lr ; When the current i corresponding to the energy storage inductor is monitored Lr Reaching the preset first current value I n1 , according to the control signal, the Boost converter is controlled to switch from the first mode to other modes in sequence to achieve soft switching control of the Boost converter; wherein the first current value I n1 A first preset condition is met, and the first preset condition is set according to the terminal voltage of the energy storage filter capacitor EC2, the parasitic capacitance C1 of the switch tube, and the energy storage inductor.

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