A dc-dc converter, control system and voltage balancing control method

Abstract

The application belongs to the technical field of power electronic conversion and control, and particularly relates to a DC-DC converter, a control system and a voltage balance control method. The DC-DC converter comprises a first inductor L1, a second inductor L2, a first switch tube Sw1, a second switch tube Sw2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, an output capacitor C5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5 and an output resistor R1. The application can realize multi-stage capacitor voltage balance control, improve the output voltage stability and operation reliability of the converter, and reduce the voltage stress of the switch device and the system loss.

Description

Technical Field

[0001] This invention belongs to the field of power electronic conversion and control technology, specifically relating to a DC-DC converter, a control system, and a voltage balance control method. Background Technology

[0002] Traditional Boost converters have a simple structure, but they often require extremely high duty cycles under high-gain operating conditions. This not only leads to a significant increase in voltage stress on the switching devices, but also causes problems such as increased conduction losses, decreased efficiency, and deteriorated system stability. To solve this problem, existing technologies introduce multi-stage energy storage and voltage superposition mechanisms to achieve higher voltage gains under lower duty cycle conditions.

[0003] However, in high-gain DC-DC converters with multi-stage switched capacitor structures, the voltage of each capacitor stage easily deviates from its theoretical design value due to factors such as capacitor parameter dispersion, differences in equivalent series resistance, inconsistent switching actions, and temperature variations, resulting in an unbalanced capacitor voltage distribution. When the capacitor voltage is unbalanced, it not only causes increased output voltage fluctuations but may also lead to excessive voltage stress on some switching devices and diodes, thereby reducing system reliability and shortening device lifespan. To address these issues, existing technologies typically employ a single output voltage closed-loop control method for regulation. However, this method primarily focuses on output voltage regulation performance and struggles to effectively constrain the internal voltage distribution of multiple capacitor stages, thus failing to fundamentally solve the capacitor voltage imbalance problem.

[0004] Chinese patent publication number CN107104590A, entitled "A Quasi-Switching Boost DC / DC Converter Based on a Switching Inductor," describes a patent application where the cathode of a first diode is connected to the negative terminal of the DC input power supply and the source of a first switching transistor; the positive terminal of the DC input power supply is connected to one end of the first inductor, the anode of the second diode, and the anode of the sixth diode; the cathode of a third diode is connected to one end of the second inductor and the cathode of the second diode; and the other end of the second inductor is connected to the cathode of a fourth diode, the anode of a fifth diode, and the drain of the second switching transistor. This patent application only has a single energy storage capacitor and lacks a multi-stage switched capacitor network. Therefore, it cannot solve the technical problems of output voltage fluctuations and increased voltage stress on power devices caused by uneven voltage distribution across multiple capacitor stages. Summary of the Invention

[0005] To overcome the problems existing in the prior art, the present invention aims to provide a DC-DC converter, a control system, and a voltage balance control method. Addressing the issues of capacitor voltage distribution imbalance, decreased output voltage stability, and increased voltage stress on power devices in multi-stage switched capacitor networks of existing high-gain DC-DC converters, the present invention constructs a capacitor voltage feedback closed-loop control system to achieve multi-stage capacitor voltage balance control, thereby improving the converter's output voltage stability and operational reliability, and reducing voltage stress on switching devices and system losses.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a DC-DC converter, comprising: a first inductor L1, a second inductor L2, a first switching transistor Sw1, a second switching transistor Sw2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, an output capacitor C5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and an output resistor R1; The positive terminal of the input power supply Vin is connected to the drain of the first switching transistor Sw1, the first terminal of the second inductor L2, and the anode of the first diode D1; the negative terminal of the input power supply Vin is connected to the second terminal of the first inductor L1, the source of the second switching transistor Sw2, the second terminal of the output capacitor C5, and the second terminal of the output resistor R1; the source of the first switching transistor Sw1 is connected to the first terminal of the first inductor L1, the second terminal of the first capacitor C1, and the second terminal of the third capacitor C3; the cathode of the first diode D1 is connected to the first terminal of the first capacitor C1 and the anode of the second diode D2; the cathode of the second diode D2 is connected to the first terminal of the second capacitor C2 and the anode of the third diode D3; the cathode of the third diode D3 is connected to the first terminal of the third capacitor C3 and the anode of the fourth diode D4; the cathode of the fourth diode D4 is connected to the first terminal of the fourth capacitor C4 and the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the first terminal of the output capacitor C5 and the first terminal of the output resistor R1; the drain of the second switching transistor Sw2 is connected to the second terminal of the second inductor L2, the second terminal of the second capacitor C2, and the second terminal of the fourth capacitor C4.

[0007] Optionally, the first switch Sw1 and the second switch Sw2 are both metal-oxide-semiconductor field-effect transistors or both insulated-gate bipolar transistors.

[0008] Optionally, the inductance values ​​of the first inductor L1 and the second inductor L2 are equal.

[0009] Optionally, the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 are all fast recovery diodes or Schottky diodes.

[0010] Secondly, the present invention provides a capacitor voltage balance control system for a DC-DC converter, including an input power supply Vin, a voltage sampling module, a controller module, a PWM drive module, and the DC-DC converter; the voltage sampling module is used to collect the voltage signals of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 in real time, and send the collected signals to the controller module; the controller module is used to calculate the reference voltage values ​​of each capacitor according to the input voltage and the duty cycle of the DC-DC converter, and compare the real-time collected capacitor voltages with the corresponding reference voltages to obtain the voltage errors of each capacitor; a comprehensive voltage balance error is constructed based on the voltage errors of each capacitor, and a duty cycle compensation amount is generated; the PWM drive module is used to correct the drive signals of the first switch Sw1 and the second switch Sw2 according to the duty cycle compensation amount.

[0011] Thirdly, the present invention provides a voltage balance control method for a DC-DC converter, applied to the capacitor voltage balance control system of the converter, comprising the following steps: S1: Collect the actual voltages of the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor; S2: Calculate the reference voltage of each capacitor according to the input voltage Vin and the current operating duty cycle d, based on the steady-state operating model of the converter; S3: Compare the actual voltage of each capacitor with the corresponding reference voltage to obtain the voltage error of each capacitor; S4: Based on the positional relationship of each capacitor in the cascaded boost structure, the voltage errors of each capacitor are fused to construct a comprehensive voltage balance error; S5: Generate duty cycle compensation Δd based on the comprehensive voltage balance error; S6: Correct the duty cycle of the PWM drive signal using the aforementioned duty cycle compensation amount to obtain the corrected duty cycle d. ; S7: The converter is driven by the modified PWM drive signal to achieve stable output voltage and balanced voltage control of each capacitor stage.

[0012] Optionally, in step S2, the theoretical reference values ​​of the capacitor voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are respectively: ; ; ; Where Vin is the input voltage and d is the duty cycle.

[0013] Optionally, in step S4, the formula for calculating the comprehensive voltage balance error E is: or .

[0014] Optionally, in step S4, the formula for calculating the comprehensive voltage balance error E is: E=k1e1+k2e2+k3e3+k4e4. Where k is a weighting coefficient, and the weighting coefficient k is set to be proportional to the reference voltage.

[0015] Optionally, in step S5, the duty cycle compensation amount Δd is generated by a proportional-integral control algorithm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention introduces a capacitor voltage feedback control mechanism to dynamically adjust the voltage of each capacitor in a multi-stage switched capacitor network, improving voltage distribution uniformity. While ensuring stable output voltage, it effectively reduces voltage stress on power devices and diodes, enhancing system reliability. By dynamically compensating for the duty cycle, it achieves adaptive adjustment of the converter under different operating conditions, improving system dynamic response performance. This invention requires no additional power switching devices; voltage balance control is achieved solely through voltage sampling and digital control algorithms, resulting in a simple structure and low cost. It is suitable for high-gain DC-DC conversion applications such as photovoltaic power generation systems, fuel cell systems, electric vehicle power supply systems, and DC microgrids.

[0017] Furthermore, the control method of this invention can effectively suppress uneven voltage distribution in multi-stage switched capacitor networks, improve output voltage stability, reduce voltage stress on power devices, and enhance system dynamic response performance and operational reliability. This invention has a simple structure, is easy to implement digitally, and can be widely applied in high-gain DC-DC conversion applications such as photovoltaic power generation, fuel cells, electric vehicles, and DC microgrids. Attached Figure Description

[0018] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the invention in any way. Furthermore, the shapes and proportions of the components in the drawings are merely schematic to aid in understanding the invention and do not specifically limit the shapes and proportions of the components. In the drawings: Figure 1 This is a circuit topology diagram of a DC-DC converter according to an embodiment of the present invention; Figure 2 This is a dual-inductor energy storage mode diagram according to an embodiment of the present invention; Figure 3 This is a modal diagram of the boost converter in an embodiment of the present invention; Figure 4 This is a flowchart illustrating the voltage balance control process according to an embodiment of the present invention. Figure 5 This is a diagram of a capacitor voltage feedback control system according to an embodiment of the present invention. Detailed Implementation

[0019] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0020] Therefore, the following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0021] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0022] When an element is referred to as being "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only embodiments. The use of the term "horizontal" does not imply that the component is required to be absolutely horizontal, but rather that it may be slightly tilted. "Horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it may be slightly tilted.

[0023] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the specification and appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0025] The present invention will now be described in detail with reference to the accompanying drawings.

[0026] The present invention discloses a capacitor voltage balance control system for a DC-DC converter, comprising an input power supply Vin, a voltage sampling module, a controller module, a PWM drive module, and a DC-DC converter.

[0027] The present invention provides a DC-DC converter comprising: a first inductor L1, a second inductor L2, a first switching transistor Sw1, a second switching transistor Sw2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, an output capacitor C5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and an output resistor R1.

[0028] The positive terminal of the input power supply Vin is connected to the drain of the first switching transistor Sw1, the first terminal of the second inductor L2, and the anode of the first diode D1; the negative terminal of the input power supply Vin is connected to the second terminal of the first inductor L1, the source of the second switching transistor Sw2, the second terminal of the output capacitor C5, and the second terminal of the output resistor R1; the source of the first switching transistor Sw1 is connected to the first terminal of the first inductor L1, the second terminal of the first capacitor C1, and the second terminal of the third capacitor C3; the cathode of the first diode D1 is connected to the first terminal of the first capacitor C1 and the anode of the second diode D2; the cathode of the second diode D2 is connected to the first terminal of the second capacitor C2 and the anode of the third diode D3; the cathode of the third diode D3 is connected to the first terminal of the third capacitor C3 and the anode of the fourth diode D4; the cathode of the fourth diode D4 is connected to the first terminal of the fourth capacitor C4 and the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the first terminal of the output capacitor C5 and the first terminal of the output resistor R1; the drain of the second switching transistor Sw2 is connected to the second terminal of the second inductor L2, the second terminal of the second capacitor C2, and the second terminal of the fourth capacitor C4.

[0029] The voltage sampling module is used to acquire the voltage signals of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 in real time, and send the acquired signals to the controller module. The controller module is used to calculate the reference voltage values ​​of each capacitor according to the input voltage and the duty cycle of the DC-DC converter, and compare the real-time acquired capacitor voltages with the corresponding reference voltages to obtain the voltage errors of each capacitor. Based on the voltage errors of each capacitor, a comprehensive voltage balance error is constructed, and a duty cycle compensation amount is generated. The PWM drive module is used to correct the drive signals of the first switch Sw1 and the second switch Sw2 according to the duty cycle compensation amount.

[0030] This invention constructs a capacitor voltage feedback closed-loop control system to achieve multi-stage capacitor voltage balance control, improving the stability and reliability of the converter's output voltage while reducing voltage stress on switching devices and system losses. The DC-DC converter circuit of this invention features dual inductors, a multi-stage switched capacitor network, diodes, and an output capacitor, enabling high-gain conversion from low-voltage DC to high-voltage DC. A voltage sampling module acquires real-time capacitor voltage information at each stage. The controller module establishes a capacitor reference voltage model based on the input voltage and duty cycle, compares the reference voltage with the actual capacitor voltage to obtain the voltage error, and then generates a duty cycle compensation amount to dynamically correct the PWM drive signal, achieving balanced capacitor voltage control at each stage.

[0031] Example 1 A capacitor voltage balance control system for a DC-DC converter includes an input power supply Vin, a DC-DC converter, a voltage sampling module, a controller module, and a PWM drive module.

[0032] like Figure 1 As shown, a DC-DC converter in this embodiment includes: a first inductor L1, a second inductor L2, a first switching transistor Sw1, a second switching transistor Sw2, a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, an output capacitor C5, a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, and an output resistor R1.

[0033] The positive terminal of the input power supply Vin is connected to the drain of the first switching transistor Sw1, the first terminal of the second inductor L2, and the anode of the first diode D1; the negative terminal of the input power supply Vin is connected to the second terminal of the first inductor L1, the source of the second switching transistor Sw2, the second terminal of the output capacitor C5, and the second terminal of the output resistor R1; the source of the first switching transistor Sw1 is connected to the first terminal of the first inductor L1, the second terminal of the first capacitor C1, and the second terminal of the third capacitor C3; the cathode of the first diode D1 is connected to the first terminal of the first capacitor C1 and the anode of the second diode D2; the cathode of the second diode D2 is connected to the first terminal of the second capacitor C2 and the anode of the third diode D3; the cathode of the third diode D3 is connected to the first terminal of the third capacitor C3 and the anode of the fourth diode D4; the cathode of the fourth diode D4 is connected to the first terminal of the fourth capacitor C4 and the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the first terminal of the output capacitor C5 and the first terminal of the output resistor R1; the drain of the second switching transistor Sw2 is connected to the second terminal of the second inductor L2, the second terminal of the second capacitor C2, and the second terminal of the fourth capacitor C4.

[0034] Optionally, the first switch Sw1 and the second switch Sw2 are both metal-oxide-semiconductor field-effect transistors or both insulated-gate bipolar transistors.

[0035] Optionally, the inductance values ​​of the first inductor L1 and the second inductor L2 are equal.

[0036] Optionally, the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 are all fast recovery diodes or Schottky diodes.

[0037] The voltage sampling module is used to acquire the voltage signals of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 in real time, and send the acquired signals to the controller module. The first inductor L1 and the second inductor L2 form a switched inductor network, the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 form a switched capacitor network, and the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 form an energy transfer path, collectively forming a high gain (higher than 1 / (1) of the gain of a traditional Boost converter). The boost topology of D).

[0038] Based on the energy transfer path of the DC-DC converter, the controller module establishes reference voltage models for each capacitor stage under different operating modes, creating a dynamic mapping relationship between the reference voltage of each capacitor stage and the input voltage and duty cycle. Specifically, the controller module generates capacitor voltage errors based on the deviation between the actual voltage of each capacitor stage and its corresponding reference voltage. It then fuses these capacitor voltage errors according to the positional relationship of each capacitor stage in the cascaded energy transfer path, forming a comprehensive voltage balance error that characterizes the overall degree of capacitor voltage imbalance.

[0039] The controller module generates a duty cycle adjustment based on the comprehensive voltage balance error and performs closed-loop correction on the PWM drive signal, causing the dual switching transistors to periodically switch between two operating modes. This achieves high-gain DC-DC conversion while simultaneously enabling dynamic equalization control of the multi-stage capacitor voltage and stable output voltage control.

[0040] Specifically, the controller module uses a digital signal processor, a microcontroller, a field-programmable gate array, or a digital controller.

[0041] The PWM drive module corrects the drive signals of the first switch Sw1 and the second switch Sw2 according to the duty cycle compensation. After the duty cycle is corrected, the DC-DC converter is controlled to operate, thereby achieving balanced control of capacitor voltages at each stage and stable control of the output voltage.

[0042] like Figure 2 As shown, in the first operating mode, the first switch Sw1 and the second switch Sw2 are turned on simultaneously, so that the first inductor L1 and the second inductor L2 store energy at the same time.

[0043] like Figure 3 As shown, in the second operating mode, the first switch Sw1 and the second switch Sw2 are turned off simultaneously, so that the energy of the first inductor L1 and the second inductor L2 is transferred step by step to each stage of capacitors, namely the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the output capacitor C5, through the diode network, namely the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5, thereby achieving voltage superposition.

[0044] The converter gain characteristics are mapped based on the input voltage and duty cycle to characterize the target voltage values ​​of each capacitor stage during steady-state operation. The overall voltage balance error is obtained by weighting and fusing the voltage errors of each capacitor stage according to their position weights in the cascaded structure. The duty cycle compensation is generated by the proportional-integral controller based on the overall voltage balance error and is used to adjust the PWM drive signal. The voltage sampling module is used to detect the voltage of each capacitor stage in real time and input the sampled signal to the controller module to form closed-loop control. Through voltage feedback control, the voltage of each capacitor stage is kept balanced during dynamic operation, thereby reducing voltage stress and improving system stability. The PWM drive module outputs the corrected duty cycle d. , and: d =d+Δd.

[0045] This embodiment provides a voltage balance control method for a DC-DC converter, applied to the capacitor voltage balance control system of a DC-DC converter, comprising the following steps: S1: The voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 of the DC-DC converter are acquired in real time through the voltage sampling module. The sampled signals are transmitted to the controller module as feedback input.

[0046] S2: Calculate the reference voltages of each capacitor stage based on the input voltage Vin and the duty cycle d. The reference voltages of each capacitor stage are established based on the converter's steady-state operating model and are related to the input voltage and duty cycle. The reference voltages of each capacitor stage are functions of the input voltage Vin and the duty cycle d.

[0047] ; ; ; ; .

[0048] Where Vin is the input voltage, and Vc1 Vc2 Vc3 Vc4 and Vc5 These are the theoretical reference values ​​of the capacitor voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the output capacitor C5, respectively, and Vo is the output voltage.

[0049] S3: Compare the actual voltage of the capacitor with the reference voltage to obtain the voltage error.

[0050]

[0051] Where e is the voltage error, Vc1, Vc2, Vc3, and Vc4 are the actual voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4, respectively, and i = 1, 2, 3, and 4.

[0052] S4: Construct a comprehensive voltage balance error based on the voltage error. The comprehensive voltage balance error is used to characterize the overall deviation of the voltage of each capacitor.

[0053] S5: The controller module generates the duty cycle compensation amount Δd based on the comprehensive voltage balance error.

[0054] The duty cycle compensation is calculated using a proportional-integral (PI) control algorithm. The duty cycle compensation can be generated using proportional control, proportional-integral (PI) control, proportional-integral-derivative (PI-DE) control, or digital closed-loop control algorithms. This compensation is used to dynamically correct the duty cycle of the PWM drive signal.

[0055] S6: The duty cycle of the PWM drive signal is corrected using the duty cycle compensation. The controller module outputs the duty cycle compensation to the PWM drive module to generate synchronous drive signals for the first switch Sw1 and the second switch Sw2. Coordinated control of the inductor energy storage and capacitor charging / discharging processes is achieved by adjusting the duty cycle d.

[0056] S7: Drives the converter to operate, achieving stable output voltage and balanced voltage control of each capacitor stage.

[0057] Multi-stage capacitor voltage balance control and output voltage stability control can be achieved without adding additional power switching devices.

[0058] Example 2 This embodiment provides a capacitor voltage balance control system for a DC-DC converter, including an input power supply Vin, a high-gain DC-DC converter main circuit, a voltage sampling module, a controller module, and a PWM drive module.

[0059] like Figure 4 As shown, the voltage balance control method for the DC-DC converter in this embodiment is applied to the capacitor voltage balance control system of the DC-DC converter, and includes the following steps: S1: Acquire the voltage of each capacitor stage; S2: Calculate the reference voltage of each capacitor stage; S3: Calculate the voltage error; S4: Construct the comprehensive voltage balance error; S5: Generate the duty cycle compensation amount; S6: Correct the PWM duty cycle; S7: Drive the converter to run and realize capacitor voltage balance control.

[0060] like Figure 5 As shown, the voltage sampling module is used to collect the terminal voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 in real time, and input the collected signals into the controller module.

[0061] The controller module is implemented using a digital controller, specifically a DSP, a microcontroller, or an FPGA.

[0062] The controller module establishes reference voltage models for each stage of the capacitors based on the input voltage Vin and the converter's duty cycle d. The expression for these models is: ; ; ; ; .

[0063] Where Vin represents the input voltage, and Vc1 Vc2 Vc3 Vc4 and Vc5 These are the theoretical reference values ​​for the capacitor voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, the fourth capacitor C4, and the output capacitor C5, respectively.

[0064] The controller module compares the actual voltages VC1, VC2, VC3, and VC4 of each capacitor with the corresponding reference voltages to obtain the voltage error.

[0065] i = 1, 2, 3, 4 Furthermore, the controller module constructs a comprehensive voltage balance error based on the voltage error: Optionally, the overall voltage balance error E is: Alternatively, use the sum of squares form. .

[0066] Optionally, the overall voltage balance error E is: E = k1e1 + k2e2 + k3e3 + k4e4. Where k is a weighting coefficient, which is set to be proportional to the reference voltage. k1:k2:k3:k4 = Vc1 :Vc2 :Vc3 :Vc4 Based on the weights of each capacitor in the DC-DC converter, the four voltage errors are weighted and fused to form a comprehensive voltage balance error E that characterizes the overall degree of imbalance.

[0067] The controller generates the duty cycle compensation amount Δd based on the overall voltage balance error, and its expression is as follows:

[0068] Among them, K p K is the proportionality coefficient. i is the integral coefficient.

[0069] The PWM drive module uses the corrected duty cycle d Generate drive signals, where: d =d + Δd The first switch Sw1 and the second switch Sw2 are controlled to turn on and off synchronously, thereby achieving stable operation of the high-gain DC-DC converter.

[0070] In actual operation, due to factors such as the dispersion of capacitor parameters, temperature changes, and device aging, the voltage of each capacitor may deviate from its theoretical reference value. This invention introduces capacitor voltage feedback closed-loop control, enabling the voltage of each capacitor to dynamically track its reference value, thereby achieving capacitor voltage balance control, reducing output voltage fluctuations, and improving system stability.

[0071] Unless otherwise specified, the equipment components involved in the above embodiments are all conventional equipment components, and the structural settings, working methods or control methods involved are all conventional settings, working methods or control methods in the art unless otherwise specified.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the spirit and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A DC-DC converter, characterized in that, include: First inductor L1, second inductor L2, first switching transistor Sw1, second switching transistor Sw2, first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, output capacitor C5, first diode D1, second diode D2, third diode D3, fourth diode D4, fifth diode D5, and output resistor R1; The positive terminal of the input power supply Vin is connected to the drain of the first switching transistor Sw1, the first terminal of the second inductor L2, and the anode of the first diode D1; the negative terminal of the input power supply Vin is connected to the second terminal of the first inductor L1, the source of the second switching transistor Sw2, the second terminal of the output capacitor C5, and the second terminal of the output resistor R1; the source of the first switching transistor Sw1 is connected to the first terminal of the first inductor L1, the second terminal of the first capacitor C1, and the second terminal of the third capacitor C3; the cathode of the first diode D1 is connected to the first terminal of the first capacitor C1 and the anode of the second diode D2; the cathode of the second diode D2 is connected to the first terminal of the second capacitor C2 and the anode of the third diode D3; the cathode of the third diode D3 is connected to the first terminal of the third capacitor C3 and the anode of the fourth diode D4; the cathode of the fourth diode D4 is connected to the first terminal of the fourth capacitor C4 and the anode of the fifth diode D5; the cathode of the fifth diode D5 is connected to the first terminal of the output capacitor C5 and the first terminal of the output resistor R1; the drain of the second switching transistor Sw2 is connected to the second terminal of the second inductor L2, the second terminal of the second capacitor C2, and the second terminal of the fourth capacitor C4.

2. A DC-DC converter according to claim 1, characterized in that, The first switch Sw1 and the second switch Sw2 are both metal-oxide-semiconductor field-effect transistors or both insulated-gate bipolar transistors.

3. A DC-DC converter according to claim 1, characterized in that, The inductance values ​​of the first inductor L1 and the second inductor L2 are equal.

4. A DC-DC converter according to claim 1, characterized in that, The first diode D1, the second diode D2, the third diode D3, the fourth diode D4, and the fifth diode D5 are all fast recovery diodes or Schottky diodes.

5. A capacitor voltage balance control system for a DC-DC converter, comprising an input power supply Vin, a voltage sampling module, a controller module, a PWM drive module, and the DC-DC converter as described in any one of claims 1 to 4; the voltage sampling module is used to acquire voltage signals of a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4 in real time, and send the acquired signals to the controller module; the controller module is used to calculate reference voltage values ​​of each capacitor stage based on the input voltage and the duty cycle of the DC-DC converter, and compare the real-time acquired capacitor voltages with the corresponding reference voltages to obtain the voltage errors of each capacitor stage; construct a comprehensive voltage balance error based on the voltage errors of each capacitor stage, and generate a duty cycle compensation amount; the PWM drive module is used to correct the drive signals of the first switch Sw1 and the second switch Sw2 based on the duty cycle compensation amount.

6. A voltage balance control method for a DC-DC converter, applied to the capacitor voltage balance control system of the converter as described in claim 5, characterized in that, Includes the following steps: S1: Collect the actual voltages of the first capacitor, the second capacitor, the third capacitor, and the fourth capacitor; S2: Calculate the reference voltage of each capacitor according to the input voltage Vin and the current operating duty cycle d, based on the steady-state operating model of the converter; S3: Compare the actual voltage of each capacitor with the corresponding reference voltage to obtain the voltage error of each capacitor; S4: Based on the positional relationship of each capacitor in the cascaded boost structure, the voltage errors of each capacitor are fused to construct a comprehensive voltage balance error; S5: Generate duty cycle compensation Δd based on the comprehensive voltage balance error; S6: Correct the duty cycle of the PWM drive signal using the aforementioned duty cycle compensation amount to obtain the corrected duty cycle d. ; S7: The converter is driven by the modified PWM drive signal to achieve stable output voltage and balanced voltage control of each capacitor stage.

7. The voltage balance control method for a DC-DC converter according to claim 6, characterized in that, In step S2, the theoretical reference values ​​of the capacitor voltages of the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are as follows: ; ; ; Where Vin is the input voltage and d is the duty cycle.

8. A voltage balance control method for a DC-DC converter according to claim 6, characterized in that, In step S4, the formula for calculating the comprehensive voltage balance error E is: or .

9. A voltage balance control method for a DC-DC converter according to claim 6, characterized in that, In step S4, the formula for calculating the comprehensive voltage balance error E is: E=k1e1+k2e2+k3e3+k4e4. Where k is a weighting coefficient, which is set to be proportional to the reference voltage.

10. A voltage balance control method for a DC-DC converter according to claim 6, characterized in that, In step S5, the duty cycle compensation amount Δd is generated by a proportional-integral control algorithm.

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