A control method and system of a high-power four-switch buck-boost converter

Abstract

This invention belongs to the field of power electronics technology and relates to a control method and system for a high-power four-switch buck-boost converter. The method includes the following steps: acquiring input and output voltages; determining the maximum operating time of the direct power transfer mode and the actual closed-loop output parameters of the PI controller; determining the maximum value of the PI controller's closed-loop output parameters; determining the duration of the charging, direct power transfer, reset, and freewheeling modes; and controlling the four switching transistors in the four-switch buck-boost converter. This invention can adaptively determine the maximum operating time of the direct power transfer mode and the maximum value of the PI controller's closed-loop output parameters under soft-switching critical continuous mode based on the input-output voltage relationship. By comparing the PI controller's closed-loop output parameters with the aforementioned parameters, the duration of each operating mode is reasonably determined, and drive signals are generated. Thus, through precise timing of each operating mode, the inductor current maintains a reasonable ripple range in both soft-switching and hard-switching modes.

Description

Technical Field

[0001] This invention belongs to the field of power electronics technology and relates to a control method and system for a high-power four-switch buck-boost converter. Background Technology

[0002] As the core support for communication equipment, the stable and reliable power supply of communication power is crucial for ensuring the uninterrupted operation of communication networks. A typical communication power system operates by having an AC / DC converter transform the mains input into a 48V output to the DC bus, which is then distributed to various loads via a power distribution module. To ensure uninterrupted operation of communication equipment, a battery bank can serve as a backup power source, providing normal operating voltage to the DC bus in case of AC / DC converter or mains input failure. However, since the voltage fluctuation range of the battery bank is wide during charging and discharging, it is necessary to use a DC / DC converter to convert this dynamically changing DC voltage into a stable 48V output to the DC bus. Furthermore, when there are many communication devices, the power transfer capability of the DC / DC converter must be considered to adapt to high-power applications. The four-switch Buck-Boost converter, also known as a four-switch buck-boost converter, is ideally suited as the DC / DC module for communication power systems due to its low voltage stress, few passive components, and high power density.

[0003] Currently, mainstream research on four-switch buck-boost converters focuses on the 300W power level, exploring high-efficiency implementation paths over a wide voltage input range. To further increase power levels, soft-switching technology is typically employed, optimizing the turn-on and turn-off timings of the switching transistors and suppressing switching losses to meet higher power demands. However, this process significantly increases inductor current ripple, leading to increased losses and decreased conversion efficiency in the four-switch buck-boost converter. This severely limits its application in high-power communication power supply scenarios and fails to meet the power requirements of communication power systems in practical engineering projects. Summary of the Invention

[0004] The purpose of this invention is to provide a control method and system for a high-power four-switch buck-boost converter, which can improve the power level of the four-switch buck-boost converter while suppressing inductor current ripple, reducing converter losses and ensuring high conversion efficiency, thus meeting the practical application needs of high-power communication power supply scenarios.

[0005] To achieve the above objectives, the technical solution provided by the present invention is as follows: A control method for a high-power four-switch buck-boost converter includes the following steps: Collect the input and output voltages of the four-switch buck-boost converter; Based on the relationship between the input and output voltages of the four-switch buck-boost converter, the maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under the soft-switching critical continuous mode is determined. At the same time, the error voltage is obtained by comparing the output voltage of the four-switch buck-boost converter with its given reference voltage. The error voltage is then PI-regulated to obtain the actual closed-loop output parameters of the PI controller. Based on the relationship between the input and output voltages of the four-switch buck-boost converter and the maximum operating time of the direct power transfer mode, the maximum value of the closed-loop output parameter of the PI controller in the soft-switching continuous mode of the four-switch buck-boost converter is determined. Based on the actual closed-loop output parameters of the PI controller, and by comparing them with the maximum operating time of the power direct transfer mode and the maximum value of the closed-loop output parameters of the PI controller, the duration of the charging mode, the duration of the power direct transfer mode, the duration of the reset mode, and the duration of the freewheeling mode of the four-switch buck-boost converter within one switching cycle are determined. Based on the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode, drive signals are generated to control the four switching transistors in the four-switch buck-boost converter, and these signals are used to control the four switching transistors in the four-switch buck-boost converter.

[0006] The invention is further characterized by: The following formula is used to determine the maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under soft-switching critical continuous mode: , In the formula, T 2_max This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

[0007] The minimum inductor current required for each power switch in the four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on is determined by the following formula: , In the formula,I ZVS To achieve the minimum inductor current required for each power switch in the four-switch buck-boost converter to fully charge and discharge in order to complete zero-voltage turn-on, C oss The output capacitors of each power switch in the four-switch buck-boost converter. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. t dead This refers to the dead time of the two power switches on the same bridge arm in a four-switch buck-boost converter.

[0008] The maximum value of the PI controller closed-loop output parameter of the four-switch buck-boost converter in soft-switching continuous mode is determined by the following formula: , In the formula, T u_max This represents the maximum value of the closed-loop output parameter of the PI controller. T 2_max This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

[0009] When comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the direct power transfer mode and the maximum value of the PI controller's closed-loop output parameters, the four-switch buck-boost converter is in a light-load state if the actual closed-loop output parameters of the PI controller are less than the maximum operating time of the direct power transfer mode; if the actual closed-loop output parameters of the PI controller are less than the maximum value of the PI controller's closed-loop output parameters but greater than the maximum operating time of the direct power transfer mode, the four-switch buck-boost converter is in a medium-load state; and if the actual closed-loop output parameters of the PI controller are greater than the maximum value of the PI controller's closed-loop output parameters, the four-switch buck-boost converter is in a heavy-load state.

[0010] When the four-switch buck-boost converter is under light load, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode within one switching cycle are determined by the following formula: , In the formula, T 1 represents the duration of the charging mode. T 2 represents the duration of the direct power transfer mode. T 3 represents the duration of the reset mode. T 4 represents the duration of the continuous flow mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

[0011] When the four-switch buck-boost converter is under medium load, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode within one switching cycle are determined by the following formula: , In the formula, T 1 represents the duration of the charging mode. T 2 represents the duration of the direct power transfer mode. T 3 represents the duration of the reset mode. T 4 represents the duration of the continuous flow mode. T u These are the actual closed-loop output parameters of the PI controller. T 2_MAX This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on.T s The switching cycle of the four-switch buck-boost converter.

[0012] When the four-switch buck-boost converter is under heavy load, it switches to hard-switching mode. When the input voltage of the four-switch buck-boost converter is greater than the output voltage, the difference between the actual closed-loop output parameter of the PI controller and the maximum value of the PI controller's closed-loop output parameter is used as the duration of the reset mode. When the input voltage of the four-switch buck-boost converter is less than the output voltage, the difference between the actual closed-loop output parameter of the PI controller and the maximum value of the PI controller's closed-loop output parameter is used as the duration of the charging mode. The duration of the direct power transfer mode is obtained through volt-second balancing, and the duration of the freewheeling mode is zero.

[0013] A control system for a high-power four-switch buck-boost converter includes: The acquisition unit is used to acquire the input and output voltages of the four-switch buck-boost converter; The first processing unit is used to determine the maximum operating time of the four-switch buck-boost converter in the power direct transfer mode under the soft-switching critical continuous mode based on the relationship between the input voltage and the output voltage of the four-switch buck-boost converter. At the same time, it compares the output voltage of the four-switch buck-boost converter with its given reference voltage to obtain the error voltage, performs PI regulation on the error voltage, and obtains the actual closed-loop output parameters of the PI controller. The second processing unit is used to determine the maximum value of the closed-loop output parameter of the PI controller in the soft-switching continuous mode of the four-switch buck-boost converter based on the relationship between the input voltage and the output voltage of the four-switch buck-boost converter and the maximum operating time of the power direct transfer mode. The third processing unit is used to determine the duration of the charging mode, the duration of the power direct transfer mode, the duration of the reset mode, and the duration of the freewheeling mode of the four-switch buck-boost converter within one switching cycle by comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the power direct transfer mode and the maximum value of the closed-loop output parameters of the PI controller. The control unit is used to generate drive signals for controlling the four switching transistors in the four-switch buck-boost converter based on the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode, and uses these signals to control the four switching transistors in the four-switch buck-boost converter.

[0014] The control method and system for a high-power four-switch buck-boost converter of the present invention have the following advantages: This invention acquires the input and output voltages of a four-switch buck-boost converter. Based on the relationship between the input and output voltages, it determines the maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under soft-switching critical continuous mode. Simultaneously, it compares the output voltage of the four-switch buck-boost converter with a given reference voltage to obtain an error voltage. This error voltage is then PI-regulated to obtain the actual closed-loop output parameters of the PI controller. Furthermore, based on the relationship between the input and output voltages and the maximum operating time of the direct power transfer mode, it determines the maximum value of the PI controller's closed-loop output parameters in soft-switching continuous mode. Finally, it compares the actual closed-loop output parameters of the PI controller with the maximum operating time of the direct power transfer mode and the maximum value of the PI controller's closed-loop output parameters to determine the charging mode of the four-switch buck-boost converter within one switching cycle. The durations of the power direct transfer mode, reset mode, and freewheeling mode are determined. Based on these durations, drive signals are generated to control the four switching transistors in the four-switch buck-boost converter. These signals control the four switching transistors, enabling the adaptive determination of the maximum operating time of the power direct transfer mode in the soft-switching critical continuous mode and the maximum value of the PI controller closed-loop output parameter in the soft-switching continuous mode based on the input-output voltage relationship. By comparing the PI controller closed-loop output parameter with the aforementioned parameters, the duration of each operating mode is reasonably determined, and drive signals are generated. Furthermore, through precise timing of each operating mode, the inductor current maintains a reasonable ripple range in both soft-switching and hard-switching modes, effectively suppressing inductor current ripple, reducing overall converter losses, improving conversion efficiency, and broadening the power application range of the four-switch buck-boost converter, enabling it to meet the application requirements of high-power communication power supply systems. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the overall process of the present invention.

[0016] Figure 2 This is a schematic diagram of the connection structure between the system of the present invention and the four-switch buck-boost converter.

[0017] Figure 3 The diagram shows the inductor current waveform and the corresponding PWM drive waveform of the four-switch buck-boost converter of the present invention.

[0018] Figure 4 'a' is V in < V out The light carrier shape at time, b is V in < Vout The carrier waveform and c are in time. V in < V out The recarrier shape at time, d is V in > V out The light carrier shape at that time, e is V in > V out The carrier waveform and f are in time. V in > V out The recarrier shape at that time.

[0019] Figure 5 This is a comparison of efficiency curves under different control strategies of the present invention. Detailed Implementation

[0020] The technical solutions of the present invention will now be described clearly and in detail with reference to the accompanying drawings. In the description of the embodiments of the present invention, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B. "And / or" in the text is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, and B alone. Furthermore, in the description of the embodiments of the present invention, "multiple" refers to two or more. The terms "first" and "second" are used for descriptive purposes only and should not be construed as implying or suggesting relative importance or implicitly indicating the number of indicated technical features. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature.

[0021] like Figure 2 As shown, the four-switch buck-boost converter includes switching transistors Q1, Q2, Q3, and Q4, an inductor L, and an input capacitor C. in With output capacitor C out Input capacitor C inConnected between the first and second input ports of the four-switch buck-boost converter, the drain of switch Q1 is connected to the first input port of the four-switch buck-boost converter, the source of Q1 is connected to one end of inductor L, and the gate of Q1 is used to receive the drive signal. The other end of inductor L is connected to the source of switch Q4, the drain of switch Q4 is connected to the first output port of the four-switch buck-boost converter, and the gate of Q4 is used to receive the drive signal. The drain of switch Q2 is connected to the source of Q1, the source of Q2 is connected to the second input port of the four-switch buck-boost converter, and the gate of Q2 is used to receive the drive signal. The drain of switch Q3 is connected to the source of Q4, the source of Q3 is connected to the second output port of the four-switch buck-boost converter, and the gate of Q3 is used to receive the drive signal. Output capacitor C... out It is connected between the first output port and the second output port of the four-switch buck-boost converter.

[0022] like Figure 1 As shown, this invention provides a control method for a high-power four-switch buck-boost converter, applied to the aforementioned four-switch buck-boost converter, comprising the following steps: The input and output voltages of the four-switch buck-boost converter are collected.

[0023] Based on the relationship between the input and output voltages of the four-switch buck-boost converter, the maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under soft-switching critical continuous mode is determined. At the same time, the error voltage is obtained by comparing the output voltage of the four-switch buck-boost converter with its given reference voltage. The error voltage is then PI-regulated to obtain the actual closed-loop output parameters of the PI controller.

[0024] Based on the relationship between the input and output voltages of the four-switch buck-boost converter and the maximum operating time of the direct power transfer mode, the maximum value of the closed-loop output parameter of the PI controller in the soft-switching continuous mode of the four-switch buck-boost converter is determined.

[0025] Based on the actual closed-loop output parameters of the PI controller, and by comparing them with the maximum operating time of the direct power transfer mode and the maximum value of the closed-loop output parameters of the PI controller, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode of the four-switch buck-boost converter within one switching cycle are determined.

[0026] Based on the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode, drive signals are generated to control the four switching transistors in the four-switch buck-boost converter, and these signals are used to control the four switching transistors in the four-switch buck-boost converter.

[0027] In summary, this invention acquires the input and output voltages of a four-switch buck-boost converter. Based on the relationship between the input and output voltages, it determines the maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under soft-switching critical continuous mode. Simultaneously, it compares the output voltage of the four-switch buck-boost converter with its given reference voltage to obtain an error voltage. This error voltage is then PI-regulated to obtain the actual closed-loop output parameters of the PI controller. Furthermore, based on the relationship between the input and output voltages and the maximum operating time of the direct power transfer mode, it determines the maximum value of the PI controller's closed-loop output parameters in the soft-switching continuous mode. Finally, by comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the direct power transfer mode and the maximum value of the PI controller's closed-loop output parameters, it determines the charging time of the four-switch buck-boost converter within one switching cycle. The durations of the modes, including the duration of the direct power transfer mode, the reset mode, and the freewheeling mode, are determined. Based on these durations, drive signals are generated to control the four switching transistors in the four-switch buck-boost converter. These signals control the four transistors, enabling the adaptive determination of the maximum operating time of the direct power transfer mode in the soft-switching critical continuous mode and the maximum value of the PI controller closed-loop output parameter in the soft-switching continuous mode, based on the input-output voltage relationship. By comparing the PI controller closed-loop output parameter with the aforementioned parameters, the duration of each operating mode is reasonably determined, and drive signals are generated. Furthermore, through precise timing of each operating mode, the inductor current maintains a reasonable ripple range in both soft-switching and hard-switching modes, effectively suppressing inductor current ripple, reducing overall converter losses, improving conversion efficiency, and broadening the power application range of the four-switch buck-boost converter, enabling it to meet the application requirements of high-power communication power supply systems.

[0028] The maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under soft-switching critical continuous mode is determined by the following formula: , In the formula, T 2_max This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on.T s The switching cycle of the four-switch buck-boost converter.

[0029] The minimum inductor current required for each power switch in the four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on is determined by the following formula: , In the formula, I ZVS To achieve the minimum inductor current required for each power switch in the four-switch buck-boost converter to fully charge and discharge in order to complete zero-voltage turn-on, C oss The output capacitors of each power switch in the four-switch buck-boost converter. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. t dead This refers to the dead time of the two power switches on the same bridge arm in a four-switch buck-boost converter.

[0030] The maximum value of the PI controller closed-loop output parameter of the four-switch buck-boost converter in soft-switching continuous mode is determined by the following formula: , In the formula, T u_max This represents the maximum value of the closed-loop output parameter of the PI controller. T 2_max This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

[0031] Specifically, when comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the direct power transfer mode and the maximum value of the PI controller's closed-loop output parameters, if the actual closed-loop output parameters of the PI controller are less than the maximum operating time of the direct power transfer mode, the four-switch buck-boost converter is in a light-load state; if the actual closed-loop output parameters of the PI controller are less than the maximum value of the PI controller's closed-loop output parameters but greater than the maximum operating time of the direct power transfer mode, the four-switch buck-boost converter is in a medium-load state; and if the actual closed-loop output parameters of the PI controller are greater than the maximum value of the PI controller's closed-loop output parameters, the four-switch buck-boost converter is in a heavy-load state.

[0032] When the four-switch buck-boost converter is under light load, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode within one switching cycle are determined by the following formula: , In the formula, T 1 represents the duration of the charging mode. T 2 represents the duration of the direct power transfer mode. T 3 represents the duration of the reset mode. T 4 represents the duration of the continuous flow mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

[0033] When the four-switch buck-boost converter is under medium load, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode within one switching cycle are determined by the following formula: , In the formula, T 1 represents the duration of the charging mode. T 2 represents the duration of the direct power transfer mode. T 3 represents the duration of the reset mode. T 4 represents the duration of the continuous flow mode. T uThese are the actual closed-loop output parameters of the PI controller. T 2_MAX This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

[0034] When the four-switch buck-boost converter is under heavy load, it switches to hard-switching mode. When the input voltage of the four-switch buck-boost converter is greater than the output voltage, the difference between the actual closed-loop output parameter of the PI controller and the maximum value of the PI controller's closed-loop output parameter is used as the duration of the reset mode. When the input voltage of the four-switch buck-boost converter is less than the output voltage, the difference between the actual closed-loop output parameter of the PI controller and the maximum value of the PI controller's closed-loop output parameter is used as the duration of the charging mode. The duration of the direct power transfer mode is obtained through volt-second balancing, and the duration of the freewheeling mode is zero.

[0035] Specifically, when the four-switch buck-boost converter is under light load, it operates in constant frequency soft-switching discontinuous mode; when it is under medium load, it operates in variable frequency soft-switching continuous mode; and when it is under heavy load, it operates in variable frequency hard-switching mode.

[0036] like Figure 2 As shown, the present invention also provides a control system for a high-power four-switch buck-boost converter, comprising: The acquisition unit is used to acquire the input and output voltages of the four-switch buck-boost converter.

[0037] The first processing unit is used to determine the maximum operating time of the four-switch buck-boost converter in the power direct transfer mode under the soft-switching critical continuous mode based on the relationship between the input voltage and the output voltage of the four-switch buck-boost converter. At the same time, it compares the output voltage of the four-switch buck-boost converter with its given reference voltage to obtain the error voltage, performs PI regulation on the error voltage, and obtains the actual closed-loop output parameters of the PI controller.

[0038] The second processing unit is used to determine the maximum value of the closed-loop output parameter of the PI controller in the soft-switching continuous mode of the four-switch buck-boost converter based on the relationship between the input voltage and output voltage of the four-switch buck-boost converter and the maximum operating time of the direct power transfer mode.

[0039] The third processing unit is used to determine the duration of the charging mode, the duration of the power direct transfer mode, the duration of the reset mode, and the duration of the freewheeling mode of the four-switch buck-boost converter within one switching cycle by comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the power direct transfer mode and the maximum value of the closed-loop output parameters of the PI controller.

[0040] The control unit is used to generate drive signals for controlling the four switching transistors in the four-switch buck-boost converter based on the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode, and uses these signals to control the four switching transistors in the four-switch buck-boost converter.

[0041] like Figure 2 As shown, the control system of a high-power four-switch buck-boost converter of the present invention further includes a control terminal. A first processing unit, a second processing unit, a third processing unit, and a control unit are all built into the control terminal. The control unit generates drive signals for controlling the four switching transistors in the four-switch buck-boost converter according to the determined duration of each mode, and then amplifies the drive signals of the four switching transistors to drive the four switching transistors to operate. The I / O port of the control terminal is connected to an LED status light, which is used to indicate the working status of the four-switch buck-boost converter. The UART port of the control terminal is connected to a serial port display screen, which is used to display the working status and input / output parameter information of the four-switch buck-boost converter.

[0042] like Figure 3 As shown, the present invention provides an inductor current waveform and corresponding PWM drive waveform for a four-switch buck-boost converter. T 1. T 2. T 3. T 4 represents the operating duration of the four-switch buck-boost converter in each mode. I 0、 I 1. I 2 represents the inductor current value corresponding to each mode switching, (| I 0|、 I 1. I 2) ≥ I ZVS , V gs1 , V gs2 ,V gs3 , V gs4 The waveforms are the driving voltages for switching transistors Q1, Q2, Q3, and Q4, respectively. t dead Dead Zone Time Example 1 like Figure 4 As shown, based on the above control strategy, a prototype system was built and experimentally verified, as shown in the figure. V gs For the gate voltage waveform of the switching transistor, V ds Drain-source voltage waveform, i L The waveform shows the inductor current. Observation of the experimental waveform reveals that when the four-switch buck-boost converter operates under light and medium load conditions, the main switch achieves zero-voltage turn-on under these conditions, suppressing switching losses. Under heavy load conditions, it switches to hard-switching mode to balance system stability and power transfer capability. V in < V out At times, such as Figure 4 As shown in Figure a, the waveform of the four-switch buck-boost converter operating under light load conditions is as follows: At this time, switch Q2 achieves zero-voltage turn-on. V in < V out At times, such as Figure 4 As shown in Figure b, the waveform of the four-switch buck-boost converter operating under light load conditions is as follows: under these conditions, switch Q2 still maintains good zero-voltage turn-on. V in < V out At times, such as Figure 4 Figure c shows the voltage waveform of the switching transistor Q4 in a four-switch buck-boost converter under heavy load conditions. At this point, the converter switches to hard-switching mode. V in > V out At times, such as Figure 4 As shown in Figure d, the waveform of the four-switch buck-boost converter operating under medium load conditions is as follows: at this time, the switching transistor Q1 achieves zero-voltage turn-on. V in > V out At times, such as Figure 4 As shown in Figure e, the waveform of the four-switch buck-boost converter operating under light load conditions is as follows: At this time, switch Q1 achieves zero-voltage turn-on. V in > V outAt times, such as Figure 4 As shown in f, the voltage waveform of the switching transistor Q1 of the four-switch buck-boost converter under heavy load conditions is shown. At this time, the converter switches to hard-switching mode.

[0043] like Figure 5 The figure shows a comparison of the efficiency curves of a four-switch buck-boost converter under different operating conditions with two control strategies. The horizontal axis represents the output power. P 0. Observation shows that traditional control strategies under heavy load (i.e., P The efficiency drops significantly when the power demand is relatively high (0), which is due to the increased power demand and decreased power transmission ratio leading to excessive inductor current ripple, thus increasing conduction losses. P con and inductance loss P L This affects transmission efficiency. The high-power frequency conversion control strategy proposed in this invention is suitable for heavy loads (i.e.,...). P When the inductor current ripple is relatively large (0), the efficiency has a significant advantage. Firstly, it eliminates the need for excessively large inductor current ripple (L) for soft switching, and the lower frequency also reduces switching losses from hard switching, thus reducing overall losses. Secondly, the optimized power transfer ratio further reduces inductor current ripple (L), thereby improving efficiency. Simultaneously, since the inductor current ripple (L) is minimal when the input and output voltages are close, the efficiency is highest at this point, even under full load (i.e.,...). P (0=500W) Efficiency up to 97%.

[0044] It is understood that this invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of this invention. Furthermore, under the teachings of this invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of this invention. Therefore, this invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this invention are within the protection scope of this invention.

Claims

1. A control method for a high-power four-switch buck-boost converter, characterized in that, Includes the following steps: Collect the input and output voltages of the four-switch buck-boost converter; Based on the relationship between the input voltage and the output voltage of the four-switch buck-boost converter, the maximum operating time of the four-switch buck-boost converter in the direct power transfer mode under the soft-switching critical continuous mode is determined. At the same time, the error voltage is obtained by comparing the output voltage of the four-switch buck-boost converter with its given reference voltage. The error voltage is then PI-regulated to obtain the actual closed-loop output parameters of the PI controller. Based on the relationship between the input and output voltages of the four-switch buck-boost converter and the maximum operating time of the direct power transfer mode, the maximum value of the closed-loop output parameter of the PI controller in the soft-switching continuous mode of the four-switch buck-boost converter is determined. Based on the actual closed-loop output parameters of the PI controller, and by comparing them with the maximum operating time of the power direct transfer mode and the maximum value of the closed-loop output parameters of the PI controller, the duration of the charging mode, the duration of the power direct transfer mode, the duration of the reset mode, and the duration of the freewheeling mode of the four-switch buck-boost converter within one switching cycle are determined. Based on the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode, drive signals are generated to control the four switching transistors in the four-switch buck-boost converter, and these signals are used to control the four switching transistors in the four-switch buck-boost converter.

2. The control method for a high-power four-switch buck-boost converter according to claim 1, characterized in that, When determining the maximum operating time of a four-switch buck-boost converter in the direct power transfer mode under soft-switching critical continuous mode, the following formula is used: ， In the formula, T 2_max This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

3. The control method for a high-power four-switch buck-boost converter according to claim 2, characterized in that, The minimum inductor current required for each power switch in the four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on is determined by the following formula: ， In the formula, I ZVS To achieve the minimum inductor current required for each power switch in the four-switch buck-boost converter to fully charge and discharge in order to complete zero-voltage turn-on, C oss The output capacitors of each power switch in the four-switch buck-boost converter. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. t dead This refers to the dead time of the two power switches on the same bridge arm in a four-switch buck-boost converter.

4. The control method for a high-power four-switch buck-boost converter according to claim 1, characterized in that, The maximum value of the PI controller closed-loop output parameter of the four-switch buck-boost converter in soft-switching continuous mode is determined by the following formula: ， In the formula, T u_max This represents the maximum value of the closed-loop output parameter of the PI controller. T 2_max This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

5. The control method for a high-power four-switch buck-boost converter according to claim 1, characterized in that, When comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the direct power transfer mode and the maximum value of the PI controller's closed-loop output parameters, the four-switch buck-boost converter is in a light-load state if the actual closed-loop output parameters of the PI controller are less than the maximum operating time of the direct power transfer mode; if the actual closed-loop output parameters of the PI controller are less than the maximum value of the PI controller's closed-loop output parameters but greater than the maximum operating time of the direct power transfer mode, the four-switch buck-boost converter is in a medium-load state; and if the actual closed-loop output parameters of the PI controller are greater than the maximum value of the PI controller's closed-loop output parameters, the four-switch buck-boost converter is in a heavy-load state.

6. The control method for a high-power four-switch buck-boost converter according to claim 5, characterized in that, When the four-switch buck-boost converter is under light load, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode within one switching cycle are determined by the following formula: ， In the formula, T 1 represents the duration of the charging mode. T 2 represents the duration of the direct power transfer mode. T 3 represents the duration of the reset mode. T 4 represents the duration of the follow-through mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

7. The control method for a high-power four-switch buck-boost converter according to claim 5, characterized in that, When the four-switch buck-boost converter is under medium load, the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode within one switching cycle are determined by the following formula: ， In the formula, T 1 represents the duration of the charging mode. T 2 represents the duration of the direct power transfer mode. T 3 represents the duration of the reset mode. T 4 represents the duration of the follow-through mode. T u These are the actual closed-loop output parameters of the PI controller. T 2_MAX This represents the maximum operating time for the direct power transfer mode. V in This is the input voltage of the four-switch buck-boost converter. V out This is the output voltage of the four-switch buck-boost converter. L This represents the inductance value of the energy storage inductor in a four-switch buck-boost converter. I ZVS The minimum inductor current required for each power switch in a four-switch buck-boost converter to fully charge and discharge in order to achieve zero-voltage turn-on. T s The switching cycle of the four-switch buck-boost converter.

8. The control method for a high-power four-switch buck-boost converter according to claim 5, characterized in that, When the four-switch buck-boost converter is under heavy load, it switches to hard-switching mode. When the input voltage of the four-switch buck-boost converter is greater than the output voltage, the difference between the actual closed-loop output parameter of the PI controller and the maximum value of the PI controller's closed-loop output parameter is used as the duration of the reset mode. When the input voltage of the four-switch buck-boost converter is less than the output voltage, the difference between the actual closed-loop output parameter of the PI controller and the maximum value of the PI controller's closed-loop output parameter is used as the duration of the charging mode. The duration of the direct power transfer mode is obtained through volt-second balancing, and the duration of the freewheeling mode is zero.

9. A control system for a high-power four-switch buck-boost converter, characterized in that, Based on the method described in any one of claims 1 to 8, including: The acquisition unit is used to acquire the input and output voltages of the four-switch buck-boost converter; The first processing unit is used to determine the maximum operating time of the four-switch buck-boost converter in the power direct transfer mode under the soft-switching critical continuous mode based on the relationship between the input voltage and the output voltage of the four-switch buck-boost converter. At the same time, it compares the output voltage of the four-switch buck-boost converter with its given reference voltage to obtain the error voltage, performs PI regulation on the error voltage, and obtains the actual closed-loop output parameters of the PI controller. The second processing unit is used to determine the maximum value of the closed-loop output parameter of the PI controller in the soft-switching continuous mode of the four-switch buck-boost converter based on the relationship between the input voltage and the output voltage of the four-switch buck-boost converter and the maximum operating time of the power direct transfer mode. The third processing unit is used to determine the duration of the charging mode, the duration of the power direct transfer mode, the duration of the reset mode, and the duration of the freewheeling mode of the four-switch buck-boost converter within one switching cycle by comparing the actual closed-loop output parameters of the PI controller with the maximum operating time of the power direct transfer mode and the maximum value of the closed-loop output parameters of the PI controller. The control unit is used to generate drive signals for controlling the four switching transistors in the four-switch buck-boost converter based on the duration of the charging mode, the duration of the direct power transfer mode, the duration of the reset mode, and the duration of the freewheeling mode, and uses these signals to control the four switching transistors in the four-switch buck-boost converter.

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