Boost converter topology

Abstract

This application provides a boost converter topology, relating to the field of boost converter technology. The boost converter topology includes: an input module, a switching transistor module, a flying capacitor clamping module, a diode rectifier module, an output module, a pre-charge module, and a controller module. The switching transistor module includes at least three switching transistors connected in series. The diode rectifier module includes at least three power diodes connected in series. The flying capacitor clamping module includes multiple flying capacitors. The number of flying capacitors, the number of power diodes, and the number of switching transistors are related to each other. The flying capacitor clamping module is used to limit the voltage stress on each switching transistor in the switching transistor module to one-Nth of the output voltage; where N is the number of switching transistors. The boost converter topology of this application reduces the voltage stress on the switching transistors, improving the reliability and safety of the boost converter.

Description

Technical Field

[0001] This application belongs to the field of boost converter technology, specifically relating to a boost converter topology. Background Technology

[0002] As the DC voltage level of photovoltaic systems continues to rise, traditional technologies have encountered significant bottlenecks in power semiconductor devices. Currently, most mainstream and mature power devices on the market are at 1200V and below, such as IGBTs (Insulated Gate Bipolar Transistors) and SiC MOSFETs (Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistors).

[0003] When the DC voltage of the system reaches 1500V or above, if the traditional two-level or three-level topology is used, these devices will be subjected to voltage stress far exceeding their rated values. This will cause the devices to operate in an extremely unsafe state, seriously affecting their reliability and making it difficult to meet the comprehensive requirements of high reliability for high-voltage photovoltaic systems. Summary of the Invention

[0004] The technical problem to be solved by this application is to provide a boost converter topology that addresses the above-mentioned shortcomings of the prior art. Using this boost converter topology, the voltage stress of power devices is reduced, and the reliability and safety of the boost converter are improved.

[0005] This application provides a boost converter topology, including: Input module, switching transistor module, flying capacitor clamping module, diode rectifier module, output module, precharge module, and controller module; The switching module includes at least three switching devices connected in series; the diode rectifier module includes at least three power diodes connected in series; the flying capacitor clamping module includes multiple flying capacitors; the number of flying capacitors, the number of power diodes, and the number of switching devices are related to each other; The boost converter topology has nodes A, N, and P; where node N is the negative output and node P is the positive output. The input terminal of the input module is connected to the DC input terminal; The output terminal of the input module, the input terminal of the switching transistor module, and the input terminal of the diode rectifier module are connected through node A; The reference ground terminal of the input module is connected to the output terminal of the switching transistor module and the reference ground terminal of the output module through node N; Both the output terminal of the diode rectifier module and the output terminal of the output module are connected to node P. The flying capacitor clamping module is used to limit the voltage stress of each switching device in the switching module to one-Nth of the output voltage; where N is the number of switching devices. The pre-charge module is used to suppress inrush current during startup and establish a preset initial voltage for the flyback capacitor clamping module and the output module; The controller module is used to acquire signals from the input module, the flying capacitor clamping module, and the output module, and to control the operation of the switching transistor module and the pre-charge module based on the signals and a preset control algorithm.

[0006] In some implementations, the switching module includes: a switching device. S 1. Switching transistor devices S 2 and switching devices S 3; The flying capacitor clamping module includes: flying capacitor C f1 and flying capacitor C f2 The diode rectifier module includes: power diodes. D 4. Power diodes D 5. Power diodes D 6; Switching devices S The input terminal of 1 is connected to node A, and the output terminal is connected to the switching device. S The input terminals of 2 are connected to form the first internal node; Switching devices S 2's output terminal and switching device S The input terminals of 3 are connected to form a second internal node; Switching devices S The output of 3 is connected to node N; Switching devices S 1. Switching transistor devices S 2 and switching devices S The control terminals of 3 are connected to the controller module respectively; power diodes D The anode of 6 is connected to node A; power diode D 6 Cathode and Power Diode D The anode connection of 5 forms the third internal node; power diodes D 5 Cathode and Power Diode D The anode connection of 4 forms the fourth internal node; power diodes D The cathode of 4 is connected to node P; Flying capacitor Cf1 One end is connected to the first internal node, and the flying capacitor C f1 The other end is connected to the third internal node of the diode rectifier module; Flying capacitor C f2 One end is connected to the second internal node, and the flying capacitor is connected to the second internal node. C f2 The other end is connected to the fourth internal node.

[0007] In some implementations, the input module includes: a filter inductor. L and filter capacitor C in ; Filter inductor L One end is connected to the DC input terminal, and the other end is connected to node A; Filter capacitor C in One end is connected to the DC input terminal, and the other end is connected to node N.

[0008] In some implementations, the output module includes: a DC bus voltage divider capacitor. C 1 and DC bus voltage divider capacitor C 2; DC bus voltage divider capacitor C One end of 1 is connected to node P, and the other end is connected to the DC bus voltage divider capacitor. C Connect one end of 2; DC bus voltage divider capacitor C The other end of 2 is connected to node N.

[0009] In some embodiments, the pre-charge module includes: a pre-charge diode. D 7. Pre-charge diode D 8. Pre-charge protection unit; the pre-charge protection unit is used to provide current limiting during startup and is bypassed after pre-charging is completed; Precharged diode D The anode of 7 is connected to one end of the pre-charge protection unit, and the cathode is connected to the fourth internal node; Precharged diode D The anode of 8 is connected to the second internal node, and the cathode is connected to the other end of the pre-charge protection unit.

[0010] In some implementations, the boost converter topology also has node O; node O is the midpoint of the output module; the pre-charge protection unit includes: a pre-charge resistor. R and relay switch K ; Pre-charge resistor R One end is connected to the pre-charged diode D7 is connected to the anode, and the other end is connected to the relay switch. K One end is connected; relay switch K The other end is connected to the pre-charged diode via node O. D 8 cathode connection; DC bus voltage divider capacitor C The other end of 1 is connected to the DC bus voltage divider capacitor via node O. C Connect one end of 2.

[0011] In some implementations, the controller module is specifically used for: Acquisition filter inductor L Current signal, flying capacitor C f1 voltage signal, flying capacitor C f2 The voltage signal and the output voltage signal of the output module; A basic modulation wave is generated based on the output voltage and current signals; According to the flying capacitor C f1 The voltage setting value and the flying capacitor C f1 The voltage signal generates the first correction value; According to the flying capacitor C f2 The voltage setting value and the flying capacitor C f2 The voltage signal generates a second correction value; The DC modulation wave corresponding to each switching device is generated based on the basic modulation wave, the first correction amount, and the second correction amount. The switching on / off state of all switching devices in the switching module is controlled by each DC modulation wave and three triangular carrier waves with a phase difference of 120°.

[0012] In some implementations, the controller module, when generating the fundamental modulation wave based on the output voltage signal and current signal, specifically performs the following: The output voltage setpoint is compared with the output voltage signal to generate the first difference; The inductor current reference value is generated based on the first difference; The inductor current reference value is compared with the current signal to generate a second difference; The fundamental modulation wave is generated based on the second difference.

[0013] In some implementations, when the controller module controls the switching of all switching devices in the switching module according to each DC modulation wave and three triangular carrier waves with a phase difference of 120°, it is specifically used for: Each DC modulation wave is compared with its corresponding triangular carrier wave to generate on / off control information for each switching device; there is a one-to-one correspondence between the DC modulation wave and the triangular carrier wave. The switching on / off control is based on the on / off control information of each switching transistor module to control the on / off state of all switching transistor devices.

[0014] In some implementations... When the controller module compares each DC modulation wave with its corresponding triangular carrier wave to generate on / off control information for each switching device, it is specifically used for: When the DC modulation wave corresponding to the switching device S1 is greater than the triangular carrier wave corresponding to the switching device S1, the on / off control information of the switching device S1 is generated as "on". When the DC modulation wave corresponding to the switching device S1 is less than or equal to the triangular carrier wave corresponding to the switching device S1, the on / off control information of the switching device S1 is generated as off. When the DC modulation wave corresponding to the switching device S2 is greater than the triangular carrier wave corresponding to the switching device S2, the on / off control information of the switching device S2 is generated as "on". When the DC modulation wave corresponding to the switching device S2 is less than or equal to the triangular carrier wave corresponding to the switching device S2, the on / off control information of the switching device S2 is turned off. When the DC modulation wave corresponding to the switching device S3 is greater than the triangular carrier wave corresponding to the switching device S3, the on / off control information of the switching device S3 is generated as "on". When the DC modulation wave corresponding to the switching device S3 is less than or equal to the triangular carrier wave corresponding to the switching device S3, the on / off control information of the switching device S3 is turned off.

[0015] According to the boost converter topology provided in this application embodiment, the pre-charge module suppresses inrush current during startup and establishes a preset initial voltage for the flying capacitor clamping module and the output module, improving the reliability of the boost converter's initial startup. Simultaneously, the voltage stress on each switching device is limited to one-Nth of the output voltage by the switching transistor module and the flying capacitor clamping module, where N is greater than or equal to three. Compared to traditional two-level topologies that bear the entire output voltage or three-level topologies that bear half the output voltage, this significantly reduces the voltage stress on the switching devices, thereby improving their reliability and, consequently, the reliability and safety of the boost converter. Attached Figure Description

[0016] Figure 1 This diagram illustrates a boost converter topology provided in an embodiment of this application. Figure 2a This diagram illustrates mode A of the boost converter topology provided in this embodiment. Figure 2b This diagram illustrates mode B of the boost converter topology provided in an embodiment of this application. Figure 2c This diagram illustrates the mode C of the boost converter topology provided in an embodiment of this application. Figure 2d This diagram illustrates the mode D of the boost converter topology provided in an embodiment of this application. Figure 2e This diagram illustrates the mode E of the boost converter topology provided in an embodiment of this application. Figure 2f This diagram illustrates the mode F of the boost converter topology provided in an embodiment of this application. Figure 2g This diagram illustrates the mode G of the boost converter topology provided in an embodiment of this application. Figure 2h This diagram illustrates the modal H of the boost converter topology provided in this embodiment. Figure 3a This application illustrates the duty cycle of the boost converter topology provided in the embodiments of this application. Figure 1 ; Figure 3b This is a schematic diagram showing the duty cycle of the boost converter topology provided in this embodiment of the application; Figure 3c This paper presents a schematic diagram showing the duty cycle of the boost converter topology provided in an embodiment of this application. Figure 4a This diagram illustrates a soft-start schematic on the output bus side provided in an embodiment of this application. Figure 4b This diagram illustrates the soft-start schematic provided in an embodiment of this application for the input DC side. Figure 5 A schematic diagram of the boost converter control strategy provided in an embodiment of this application is shown. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solutions of this application, the application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0018] The features and exemplary embodiments of various aspects of this application will now be described in detail. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain this application and are not configured to limit this application. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples of this application.

[0019] It should be noted that, in this document, relational terms such as first and second, A, B, and C, etc., are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0020] Against the backdrop of a global energy structure transition towards low-carbon development, photovoltaic (PV) power generation systems are experiencing rapid growth. To more efficiently utilize the increasing solar energy resources and improve the overall power generation efficiency and economics of PV power plants, raising the input DC voltage level of PV inverters has become a key direction in technological evolution. Over the past decade, DC voltage has gradually increased from the initial 1000V to 1500V, and is further moving towards 2000V. This trend stems from multiple technological demands. Higher DC voltage levels bring significant advantages: First, under the same power conditions, the DC-side current is significantly reduced. This not only reduces the diameter of DC cables and lowers line transmission losses, but also simplifies the design of combiner boxes and DC switches, reducing footprint and material costs. Second, on the AC side, higher DC voltage allows inverters to output greater power at the same AC voltage level. This is particularly important for large-scale ground-mounted and offshore PV power plants, helping to reduce investment and losses in transformers and step-up stages. Furthermore, higher voltage levels can better match high-efficiency, high-power PV modules, reducing the number of modules in series, thereby reducing the risk of module mismatch and improving overall system reliability. Therefore, promoting the improvement of DC voltage levels is the core path for photovoltaics to achieve higher efficiency and lower cost per kilowatt-hour.

[0021] However, with the continuous increase in DC voltage levels of photovoltaic systems, traditional technologies have encountered significant bottlenecks in power semiconductor devices. Currently, most mainstream and mature power devices on the market are at or below 1200V, such as IGBTs and SiC MOSFETs. When the system DC voltage reaches above 1500V, if traditional two-level or three-level topologies are used, these devices will be subjected to voltage stresses far exceeding their rated values. This puts the devices in an extremely unsafe state, seriously threatening their reliability. Therefore, a new boost converter topology is needed to solve the reliability problem.

[0022] Example 1

[0023] The boost converter topology provided in this application embodiment may include the following structure: The module includes an input module, a switching transistor module, a flying capacitor clamping module, a diode rectifier module, an output module, a pre-charge module, and a controller module.

[0024] The switching module includes at least three switching devices connected in series. The diode rectifier module includes at least three power diodes connected in series. The flying capacitor clamping module includes multiple flying capacitors. The number of flying capacitors, the number of power diodes, and the number of switching devices are related.

[0025] The boost converter topology has nodes A, N, and P. Node N is the negative output terminal, and node P is the positive output terminal.

[0026] The input terminal of the input module is connected to the DC input terminal.

[0027] The output terminal of the input module, the input terminal of the switching transistor module, and the input terminal of the diode rectifier module are connected through node A.

[0028] The reference ground of the input module is connected to the output of the switching module and the reference ground of the output module through node N.

[0029] The output terminals of both the diode rectifier module and the output module are connected to node P.

[0030] The flying capacitor clamping module is used to limit the voltage stress of each switching device in the switching module to 1 / N of the output voltage. Here, N is the number of switching devices.

[0031] The precharge module is used to suppress inrush current during startup and establish a preset initial voltage for the flyback capacitor clamp module and the output module.

[0032] The controller module is used to acquire signals from the input module, the flying capacitor clamping module, and the output module, and to control the operation of the switching transistor module and the pre-charge module based on the signals and a preset control algorithm.

[0033] For example, the input module may include devices such as inductors and capacitors, the output module may include capacitors, and the pre-charge module may include devices such as resistors and relays.

[0034] Each flying capacitor in the flying capacitor clamping module is connected to an internal node in the switching transistor module and the diode rectifier module, for example, between two switching transistor devices and between two power diodes.

[0035] For example, node A is used to describe a node location in the boost converter topology. The DC input terminal is, for example, a photovoltaic (PV) module.

[0036] The number of flying capacitors, the number of power diodes, and the number of switching devices are related to each other. For example, the number of flying capacitors can be the number of switching devices minus 1, and the number of power diodes can be the same as the number of switching devices.

[0037] For example, by clamping the switching transistors in series with a flying capacitor, the voltage stress on each switching transistor is reduced to the output voltage V. out / N, which allows the use of low-voltage, low-cost, high-performance power devices.

[0038] According to the boost converter topology provided in this application embodiment, the pre-charge module suppresses inrush current during startup and establishes a preset initial voltage for the flying capacitor clamping module and the output module, improving the reliability of the boost converter's initial startup. Simultaneously, the voltage stress on each switching device is limited to one-Nth of the output voltage by the switching transistor module and the flying capacitor clamping module, where N is greater than or equal to three. Compared to traditional two-level topologies that bear the entire output voltage or three-level topologies that bear half the output voltage, this significantly reduces the voltage stress on the switching devices, thereby improving their reliability and, consequently, the reliability and safety of the boost converter.

[0039] Example 2

[0040] The boost converter topology provided in this application embodiment is further described based on the boost converter topology provided in embodiment 1 of this application.

[0041] like Figure 1 As shown, this embodiment includes three switching devices. S 1. S 2. S 3. Three power diodes D 4. D 5. D 6. Two pre-charged diodes D 7. D 8. Two flying capacitors C f1 and C f2 Two DC bus voltage divider capacitors C 1 and C 2, L For filtering inductors, C in For filtering capacitors, R For pre-charge resistor, KThis is a relay switch. The switching device includes a diode. D 1. D 2. D 3. The switching transistor can be a metal-oxide-semiconductor field-effect transistor (MOSFET), a silicon carbide metal-oxide-semiconductor field-effect transistor (SiCMOSFET), an insulated-gate bipolar transistor (IGBT), or a vertical gallium nitride high electron mobility transistor (GaNHEMT), etc., and this embodiment does not limit it.

[0042] In the boost converter topology of this embodiment: The switching transistor module includes: switching transistor devices. S 1. Switching transistor devices S 2 and switching devices S 3. The flying capacitor clamping module includes: flying capacitor C f1 and flying capacitor C f2 The diode rectifier module includes: power diodes. D 4. Power diodes D 5. Power diodes D 6.

[0043] Switching devices S The input terminal of 1 is connected to node A, and the output terminal is connected to the switching device. S Connect the input terminals of 2 to form the first internal node.

[0044] Switching devices S 2's output terminal and switching device S The input terminals of 3 are connected to form the second internal node.

[0045] Switching devices S The output of 3 is connected to node N.

[0046] Switching devices S 1. Switching transistor devices S 2 and switching devices S The control terminals of 3 are connected to the controller module respectively.

[0047] power diodes D The anode of diode 6 is connected to node A. (Power diode) D 6 Cathode and Power Diode D The anode connection of 5 forms the third internal node.

[0048] power diodes D 5 Cathode and Power Diode D The anode connection of 4 forms the fourth internal node.

[0049] power diodesD The cathode of 4 is connected to node P.

[0050] Flying capacitor C f1 One end is connected to the first internal node, and the flying capacitor C f1 The other end is connected to the third internal node of the diode rectifier module.

[0051] Flying capacitor C f2 One end is connected to the second internal node, and the flying capacitor is connected to the second internal node. C f2 The other end is connected to the fourth internal node.

[0052] For example, using three switching devices S 1. S 2. S 3. By controlling the switching devices S 1. S 2. S The on / off state of 3 can achieve eight operating modes and four voltage levels. Flying capacitor. C f1 and flying capacitor C f2 Connected between the internal nodes of the switching transistor and the internal nodes of the diode, voltage clamping is achieved, limiting the voltage stress of each switching device to V. out / 3. The series diode branch provides a path for the inductor current, which, together with the switching transistor, generates four output levels, thus making all four levels 0, V out / 3,2V out / 3, V out .

[0053] In some implementations, the input module includes: a filter inductor. L and filter capacitor C in .

[0054] Filter inductor L One end is connected to the DC input terminal, and the other end is connected to node A.

[0055] Filter capacitor C in One end is connected to the DC input terminal, and the other end is connected to node N.

[0056] For example, Figure 1 The DC input terminal is for the photovoltaic module (PV). Filter inductor. L Storing and releasing energy to achieve a boost function, the inductor current is sampled by the controller for inner-loop current control. Filter capacitor. C inFilter out input voltage ripple and stabilize the input voltage.

[0057] In some implementations, the output module includes: a DC bus voltage divider capacitor. C 1 and DC bus voltage divider capacitor C 2.

[0058] DC bus voltage divider capacitor C One end of 1 is connected to node P, and the other end is connected to the DC bus voltage divider capacitor. C Connect one end of 2.

[0059] DC bus voltage divider capacitor C The other end of 2 is connected to node N.

[0060] For example, two capacitors connected in series divide the voltage to provide the output midpoint potential V. out / 2, which is node O in the diagram.

[0061] In some embodiments, the pre-charge module includes: a pre-charge diode. D 7. Pre-charge diode D 8. Pre-charge protection unit. The pre-charge protection unit is used to provide current limiting during startup and is bypassed after pre-charging is completed.

[0062] Precharged diode D The anode of 7 is connected to one end of the pre-charge protection unit, and the cathode is connected to the fourth internal node.

[0063] Precharged diode D The anode of 8 is connected to the second internal node, and the cathode is connected to the other end of the pre-charge protection unit.

[0064] For example, the pre-charge module can provide two independent charging paths for the pre-charge function, with the PV voltage passing through... L , D 6, D 5, C f2 , D 8, C 2 form a loop, respectively for C f2 , C 1 and C 2. Charging begins. When the bus voltage is established first, the bus... C 2, D 7. Pre-charge protection unit, i.e., relay K and pre-charge resistor R , C f2 , D 2, D 1, L Forming a loopC f2 and C in Series charging, C in and C f2 The voltage is inversely proportional to its capacity.

[0065] In some implementations, the boost converter topology also includes node O. Node O is the midpoint of the output module. The pre-charge protection unit includes: a pre-charge resistor. R and relay switch K .

[0066] Pre-charge resistor R One end is connected to the pre-charged diode D 7 is connected to the anode, and the other end is connected to the relay switch. K One end is connected.

[0067] relay switch K The other end is connected to the pre-charged diode via node O. D 8 cathode connection.

[0068] DC bus voltage divider capacitor C The other end of 1 is connected to the DC bus voltage divider capacitor via node O. C Connect one end of 2.

[0069] For example, pre-charge resistor R Limit charging current during startup to suppress inrush current. Relay switch K Close the circuit after pre-charging to reduce normal operation losses.

[0070] Node O connects the output module and the pre-charge module together to form a pre-charge circuit.

[0071] In some implementations, the controller module is specifically used for: Acquisition filter inductor L Current signal, flying capacitor C f1 voltage signal, flying capacitor C f2 The voltage signal and the output voltage signal of the output module.

[0072] The basic modulation wave is generated based on the output voltage signal and current signal.

[0073] According to the flying capacitor C f1 The voltage setting value and the flying capacitor C f1 The voltage signal generates the first correction value.

[0074] According to the flying capacitor C f2 The voltage setting value and the flying capacitor C f2 The voltage signal generates a second correction value.

[0075] The DC modulation wave corresponding to each switching device is generated based on the basic modulation wave, the first correction value, and the second correction value.

[0076] The switching on / off state of all switching devices in the switching module is controlled by each DC modulation wave and three triangular carrier waves with a phase difference of 120°.

[0077] For example, dual closed-loop control (outer voltage loop + inner current loop) is implemented using output voltage and current signals to ensure stable output voltage and fast dynamic response. The flying capacitor voltage balance is ensured by adjusting the flying capacitor voltage. C f1 and flying capacitor C f2 Stability.

[0078] By using carrier phase-shift modulation with three triangular carriers that are 120° out of phase, the inductor current ripple frequency is made three times the switching frequency, thereby reducing the inductor size.

[0079] For example, the DC modulation wave corresponding to each switching device is generated based on the basic modulation wave, the first correction amount, and the second correction amount, which is specifically related to the flying capacitor balance control, and is generated by superimposing the three.

[0080] The DC modulation wave for each switching device can be generated based on the fundamental modulation wave, the first correction value, and the second correction value as follows: The switching device is generated by superimposing the basic modulation wave, 2 / 3 of the first correction value, and 1 / 3 of the second correction value. S A DC modulated wave of 1.

[0081] The switching device is generated by superimposing the basic modulation wave, 1 / 3 of the first correction value, and 1 / 3 of the second correction value. S 2 DC modulated wave.

[0082] The switching device is generated by superimposing the basic modulation wave, 1 / 3 of the first correction value, and 2 / 3 of the second correction value. S 3 DC modulated wave.

[0083] For details, please refer to Formula 1 below:

[0084] Where, d ave Based on the modulation wave, d FC1 As the first correction, dFC2 As the second correction amount, u ref1 Switching transistor devices S DC modulated wave of 1, u ref2 Switching transistor devices S DC modulated wave of 2, u ref3 Switching transistor devices S 3 DC modulated wave.

[0085] The above superposition ratio is calculated based on the flying capacitor balance control.

[0086] In some implementations, the controller module, when generating the fundamental modulation wave based on the output voltage signal and current signal, specifically performs the following: The output voltage setpoint is compared with the output voltage signal to generate the first difference.

[0087] The inductor current reference value is generated based on the first difference.

[0088] The inductor current reference value is compared with the current signal to generate a second difference value.

[0089] The fundamental modulation wave is generated based on the second difference.

[0090] For example, the inductor current reference value can be calculated based on the proportional-integral method.

[0091] In some implementations, when the controller module controls the switching of all switching devices in the switching module according to each DC modulation wave and three triangular carrier waves with a phase difference of 120°, it is specifically used for: Each DC modulation wave is compared with its corresponding triangular carrier wave to generate on / off control information for each switching device. There is a one-to-one correspondence between the DC modulation wave and the triangular carrier wave.

[0092] The switching on / off control is based on the on / off control information of each switching transistor module to control the on / off state of all switching transistor devices.

[0093] For example, there is a one-to-one correspondence between each DC modulation wave, each triangular carrier wave, and each switching device.

[0094] In some implementations, when the controller module compares each DC modulation wave with its corresponding triangular carrier wave to generate on / off control information for each switching device, it is specifically used for: When the DC modulation wave corresponding to the switching device S1 is greater than the triangular carrier wave corresponding to the switching device S1, the on / off control information of the switching device S1 is generated as "on".

[0095] When the DC modulation wave corresponding to the switching device S1 is less than or equal to the triangular carrier wave corresponding to the switching device S1, the on / off control information of the switching device S1 is generated as off.

[0096] When the DC modulation wave corresponding to the switching device S2 is greater than the triangular carrier wave corresponding to the switching device S2, the on / off control information of the switching device S2 is generated as "on".

[0097] When the DC modulation wave corresponding to the switching device S2 is less than or equal to the triangular carrier wave corresponding to the switching device S2, the on / off control information of the switching device S2 is turned off.

[0098] When the DC modulation wave corresponding to the switching device S3 is greater than the triangular carrier wave corresponding to the switching device S3, the on / off control information of the switching device S3 is generated as "on".

[0099] When the DC modulation wave corresponding to the switching device S3 is less than or equal to the triangular carrier wave corresponding to the switching device S3, the on / off control information of the switching device S3 is turned off.

[0100] The boost converter topology in this embodiment uses carrier phase-shift modulation to achieve a 3x frequency multiplication of the inductor current, which reduces inductor size and cost. Through multiple switching devices and flying capacitor clamping, the voltage stress on the power devices is reduced to 1 / 3 of the output voltage, allowing the use of mature power devices at a low cost.

[0101] Meanwhile, in multi-channel boost converter applications, the common negative bus can reduce safety compliance issues in PCB (Printed Circuit Board) layout, and also improve common-mode performance.

[0102] Using this topology in a multi-channel boost converter can reduce the number of surge protectors and lower costs.

[0103] Furthermore, by controlling the flying capacitor, the bus voltage equalization can be controlled, thereby improving control performance.

[0104] The soft-start method of the topology in this embodiment is simple, requiring only two diodes, one current-limiting resistor and one relay at the hardware level, and is low in cost.

[0105] Example 3

[0106] To better understand the boost converter topology provided in the embodiments of this application, an exemplary description is given below in conjunction with a specific application implementation.

[0107] The boost converter topology proposed in this embodiment is as follows: Figure 1 As shown. This topology contains 3 switching devices. S 1. S 2. S 3 power diodes D 4.D 5. D 6. Two pre-charged diodes D 7. D 8. Two flying capacitors C f1 and C f2 Two DC bus voltage divider capacitors C 1 and C 2, L For filtering inductors, C in For filtering capacitors, R For pre-charge resistor, K For relay switches. Define the input voltage as... V in The output voltage is defined as V out Then the voltage stress of the switch and diode is V out / 3, C f1 The voltage stress is V out / 3, C f2 The voltage stress is 2 V out / 3, D 7 and D 8. Voltage stress is V out / 2.

[0108] Figures 2a to 2h The diagram illustrates eight operating modes of the boost converter. Gray lines represent non-current paths, and gray devices represent disconnected devices. Table 1 shows the switching states of each mode and the effect of the flying capacitor. In the table, levels 0, 1, 2, and 3 represent 0, 1, 2, and 3, respectively. V out / 3,2 V out / 3, V out In the switching states, 0 and 1 represent the off and on states, respectively. An upward arrow indicates charging the flying capacitor, and a downward arrow indicates discharging it. Level 0 has one switching state, as shown in mode A. Level 1 has three redundant switching states, as shown in modes B, C, and D. Level 2 has three redundant switching states, as shown in modes E, F, and G. Level 3 has one switching state, as shown in mode H. Levels 0 and 3 have no effect on the flying capacitor voltage. The redundant switching states of levels 1 and 2 have opposite effects on the flying capacitor voltage; therefore, modes B / C or F / G are used. C f1 Charge and discharge are performed using C / D or E / G modes.C f2 The charging and discharging process keeps the flying capacitor in balance.

[0109] Table 1. Switching Status of Boost Converter

[0110] Figure 3a , Figure 3b and Figure 3c The carrier phase-shift modulation strategy of the boost converter is shown, in which Figure 3a , Figure 3b and Figure 3c These represent modulation strategies with duty cycle D in the ranges of (0, 1 / 3), (1 / 3, 2 / 3), and (2 / 3, 1). In the figure, u c1 , u c2 , u c3 It consists of three triangular carrier waves that are 120° out of phase. u ref It is a DC modulated wave (one for each switching diode, the value of duty cycle D is the same as...). u ref (related to numerical values), V AN I represents the voltage at node A relative to node N. L t1 represents the inductor current, t1 to t7 represents time, and AH represents the mode. u ref and u c1 Comparison S 1. When u ref Greater than u c1 hour, S 1 represents a high level, and vice versa. u ref and u c2 Comparison S 2, when u ref Greater than u c2 hour, S 2 represents a high level, and vice versa. u ref and u c3 Comparison S 3. When u ref Greater than u c3 hour, S 3 represents a high level, and vice versa.

[0111] When D < 1 / 3, two levels, 2 and 3, are selected. The level 3 has no influence on the flying capacitor levels. Three redundant modes, E, F, and G, are adopted to balance C f1 and C f2 the capacitor voltages respectively. When 1 / 3 < D < 2 / 3, two levels, 1 and 2, are selected. Six redundant modes, B, C, D, E, F, and G, are adopted to balance C f1 and C f2 the capacitor voltages respectively. When 2 / 3 < D < 1, two levels, 0 and 1, are selected. Three redundant modes, B, C, and D, are adopted to balance C f1 and C f2 the capacitor voltages respectively.

[0112] Figure 4a and Figure 4b show the soft - start control strategy of the boost - converter topology, which is divided into two working conditions, namely, the PV is initially powered on while the bus voltage is not established and the bus is initially powered on while the PV voltage is not established.

[0113] As Figure 4a shown, when the PV voltage is established first, the PV voltage forms a loop through L , D 6, D 5, C f2 [[]], D 8, <000时,选取2和3两个电平,其中3电平对飞跨电容电平无影响,采用E、F、G三个冗余模态来分别平衡 C C f2 [[]], C 1 and C 2 for charging. Since C f2 [[]]the capacitance value of the capacitor is much smaller than C 1 and C 2, V Cf2 [[]] = V C1 [[]] ≈ V C2 [[]]. After the circuit is stable, the input and output voltages are sampled, the duty cycle is calculated, and open - loop wave generation is performed according to the carrier - phase - shifted modulation strategy. At the same time, the mode is adjusted according to the duty - cycle range, as follows: [0 < D < 1 / 3]: Compare the C f1 [[]]and C f2 [[]]voltages with their rated values (i.e., the aforementioned voltage set values). If C f1 [[]]If it is less than its rated value, the action time of the F mode is reduced. If C f1 it is greater than its rated value, the working time of the F mode is increased. Similarly, if C f2 it is less than its rated value, the action time of the E mode is increased. If C f2 it is greater than its rated value, the working time of the E mode is reduced.

[0114] [1 / 3 < D < 2 / 3]: Compare C f1 and C f2 the voltage with its rated value. If C f1 it is less than its rated value, the time of the B mode is increased and the action time of the F mode is reduced. If C f1 it is greater than its rated value, the opposite is true. Similarly, if C f2 it is less than its rated value, the action time of the E mode is increased and the time of the D mode is reduced. If C f2 it is greater than its rated value, the opposite is true.

[0115] [2 / 3 < D < 1]: Compare C f1 and C f2 the voltage with its rated value. If C f1 it is less than its rated value, the action time of the B mode is increased. If C f1 it is greater than its rated value, the working time of the B mode is reduced. Similarly, if C f2 it is less than its rated value, the action time of the D mode is reduced. If C f2 it is greater than its rated value, the working time of the D mode is increased.

[0116] As Figure 4b shown, when the bus voltage is established first, the bus forms a loop through C 2, D 7, K , R , C f2 , D 2, D 1, L and is charged in series with C f2 and C in for charging. Cin and C f2 The voltage is inversely proportional to its capacity. When C f2 When the voltage is too low, it can be increased by raising the bus voltage. C f2 The voltage increases. After the circuit stabilizes, the flying capacitor can be balanced using an open-loop waveform generation method.

[0117] Boost converter control strategy such as Figure 5 As shown in the figure, the parameters are the same as described above and will not be repeated here. The controller module includes the various PI (Proportional-Integral) controllers shown in the figure. The boost converter employs a dual closed-loop control strategy with an outer loop for output voltage and an inner loop for inductor current. V o_ref and I L_ref These are the given reference values ​​for the outer voltage loop and the inner current loop, respectively. V o (i.e., output voltage V) out )and I L These are the actual values ​​for the outer voltage loop and the inner current loop, respectively. A PI controller is used for the voltage balancing control of the two flying capacitors. V FC1_ref and V FC2_ref They are respectively C f1 and C f2 The given reference value of the voltage, V FC1 and V FC2 They are respectively C f1 and C f2 The actual value of the voltage. (Through d) FC1 and d FC2 The voltages of the two flying capacitors are controlled separately, through d ave Control the output voltage. To achieve this control, d... ave d FC1 and d FC2 The DC modulation wave u of the three switching devices directly compared with the carrier wave is obtained. ref1 u ref2 and u ref3 Among them, d FC1 = u ref2 - u ref1 d FC2 = u ref3 - u ref2 dave For u ref1 u ref2 and u ref3 The average of the three factors, after relevant calculations, yields d. ave d FC1 and d FC2 The three elements superimpose to generate a DC modulated wave. ref1 u ref2 and u ref3 Specific superposition ratios, for example... Figure 5 As shown in Formula 1 above, where 1 / 3 and 2 / 3 are multiplicative ratios. Meanwhile, using... Figure 2a The modulation strategy in Figure 2H generates the driving pulses S1 to S3.

[0118] It is understood that the various method embodiments mentioned above in this application can be combined with each other to form combined embodiments without violating the principle and logic. Due to space limitations, this disclosure will not elaborate further. Those skilled in the art will understand that in the above methods of specific implementation, the specific execution order of each step should be determined by its function and possible internal logic.

[0119] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this application, and this application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this application, and these modifications and improvements are also considered to be within the scope of protection of this application.

Claims

1. A boost converter topology, characterized in that, include: Input module, switching transistor module, flying capacitor clamping module, diode rectifier module, output module, precharge module, and controller module; The switching transistor module includes at least three switching transistor devices connected in series; the diode rectifier module includes at least three power diodes connected in series; the flying capacitor clamping module includes multiple flying capacitors; the number of flying capacitors, the number of power diodes, and the number of switching transistor devices are related to each other; The boost converter topology has nodes A, N, and P; wherein node N is the negative output terminal and node P is the positive output terminal. The input terminal of the input module is connected to the DC input terminal; The output terminal of the input module, the input terminal of the switching transistor module, and the input terminal of the diode rectifier module are connected through node A; The reference ground terminal of the input module is connected to the output terminal of the switching transistor module and the reference ground terminal of the output module through node N. Both the output terminal of the diode rectifier module and the output terminal of the output module are connected to node P. The flying capacitor clamping module is used to limit the voltage stress of each switching device in the switching module to one-Nth of the output voltage; where N is the number of the switching devices. The pre-charge module is used to suppress inrush current during startup and to establish a preset initial voltage for the flying capacitor clamping module and the output module. The controller module is used to collect signals from the input module, the flying capacitor clamping module, and the output module, and control the operation of the switching transistor module and the pre-charge module based on the signals and a preset control algorithm.

2. The boost converter topology according to claim 1, characterized in that, The switching module includes: a switching device. S 1. Switching transistor devices S 2 and switching devices S 3; The flying capacitor clamping module includes: a flying capacitor C f1 and flying capacitor C f2 The diode rectifier module includes: power diodes. D 4. Power diodes D 5. Power diodes D 6; The switching device S The input terminal of 1 is connected to node A, and the output terminal is connected to the switching device. S The input terminals of 2 are connected to form the first internal node; The switching device S The output terminal of 2 is connected to the switching device. S The input terminals of 3 are connected to form a second internal node; The switching device S The output of 3 is connected to node N; The switching device S 1. The aforementioned switching device S 2 and the aforementioned switching device S The control terminals of 3 are respectively connected to the controller module; The power diode D The anode of 6 is connected to node A; the power diode D The cathode of 6 and the power diode D The anode connection of 5 forms the third internal node; The power diode D 5's cathode and the power diode D The anode connection of 4 forms the fourth internal node; The power diode D The cathode of 4 is connected to node P; The flying capacitor C f1 One end is connected to the first internal node, and the flying capacitor C f1 The other end is connected to the third internal node of the diode rectifier module; The flying capacitor C f2 One end is connected to the second internal node, the flying capacitor C f2 The other end is connected to the fourth internal node.

3. The boost converter topology according to claim 2, characterized in that, The input module includes: a filter inductor. L and filter capacitor C in ; The filter inductor L One end is connected to the DC input terminal, and the other end is connected to node A; The filter capacitor C in One end is connected to the DC input terminal, and the other end is connected to node N.

4. The boost converter topology according to claim 3, characterized in that, The output module includes: a DC bus voltage divider capacitor. C 1 and DC bus voltage divider capacitor C 2; The DC bus voltage divider capacitor C One end of 1 is connected to node P, and the other end is connected to the DC bus voltage divider capacitor. C Connect one end of 2; The DC bus voltage divider capacitor C The other end of 2 is connected to node N.

5. The boost converter topology according to claim 4, characterized in that, The pre-charging module includes: a pre-charging diode. D 7. Pre-charge diode D 8 and a pre-charge protection unit; the pre-charge protection unit is used to provide current limiting during startup and to be bypassed after pre-charging is completed; The precharged diode D The anode of 7 is connected to one end of the pre-charge protection unit, and the cathode is connected to the fourth internal node; The precharged diode D The anode of 8 is connected to the second internal node, and the cathode is connected to the other end of the pre-charge protection unit.

6. The boost converter topology according to claim 5, characterized in that, The boost converter topology also has node O; node O is the midpoint of the output module; the pre-charge protection unit includes: a pre-charge resistor. R and relay switch K ; The pre-charge resistor R One end is connected to the pre-charged diode D 7 is connected to the anode, and the other end is connected to the relay switch. K One end is connected; The relay switch K The other end is connected to the precharged diode via node O. D 8 cathode connection; The DC bus voltage divider capacitor C The other end of 1 is connected to the DC bus voltage divider capacitor through node O. C Connect one end of 2.

7. The boost converter topology according to claim 6, characterized in that, The controller module is specifically used for: The filter inductor is collected. L The current signal, the flying capacitor C f1 The voltage signal, the flying capacitor C f2 The voltage signal and the output voltage signal of the output module; A fundamental modulation wave is generated based on the output voltage signal and the current signal; According to the flying capacitor C f1 The voltage setting value and the flying capacitor C f1 The voltage signal generates the first correction value; According to the flying capacitor C f2 The voltage setting value and the flying capacitor C f2 The voltage signal generates a second correction value; The DC modulation wave corresponding to each switching device is generated based on the basic modulation wave, the first correction amount, and the second correction amount. The switching on / off state of all switching devices in the switching module is controlled by each of the aforementioned DC modulation waves and three triangular carrier waves with a phase difference of 120°.

8. The boost converter topology according to claim 7, characterized in that, When the controller module generates the fundamental modulation wave based on the output voltage signal and the current signal, it is specifically used for: The output voltage setting value is compared with the output voltage signal to generate a first difference; Based on the first difference, a reference value for the inductor current is calculated and generated; The inductor current reference value is compared with the current signal to generate a second difference; The fundamental modulation wave is generated based on the second difference.

9. The boost converter topology according to claim 7, characterized in that, When the controller module controls the switching on and off of all switching devices in the switching module according to each of the DC modulation waves and three triangular carrier waves with a phase difference of 120°, it is specifically used for: Each of the DC modulation waves and the corresponding triangular carrier waves is compared to generate on / off control information for each of the switching devices; there is a one-to-one correspondence between the DC modulation waves and the triangular carrier waves. The switching on / off control is used to control the switching on / off of all switching devices in the switching module.

10. The boost converter topology according to claim 9, characterized in that, When the controller module compares each of the DC modulation waves with the corresponding triangular carrier waves to generate on / off control information for each of the switching devices, it is specifically used for: When the DC modulation wave corresponding to the switching device S1 is greater than the triangular carrier wave corresponding to the switching device S1, the on / off control information of the switching device S1 is generated as "on". When the DC modulation wave corresponding to the switching device S1 is less than or equal to the triangular carrier wave corresponding to the switching device S1, the on / off control information of the switching device S1 is generated as off. When the DC modulation wave corresponding to the switching device S2 is greater than the triangular carrier wave corresponding to the switching device S2, the on / off control information of the switching device S2 is generated as "on". When the DC modulation wave corresponding to the switching device S2 is less than or equal to the triangular carrier wave corresponding to the switching device S2, the on / off control information of the switching device S2 is generated as off. When the DC modulation wave corresponding to the switching device S3 is greater than the triangular carrier wave corresponding to the switching device S3, the on / off control information of the switching device S3 is generated as "on". When the DC modulation wave corresponding to the switching device S3 is less than or equal to the triangular carrier wave corresponding to the switching device S3, the on / off control information of the switching device S3 is generated as off.

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