High-frequency chain interconnection, distributed input, serial output, modular Boost topology and control method

Abstract

This invention provides a high-frequency interconnected input-distributed output series modular Boost topology and its control method. The topology includes: a high-frequency transformer, and Boost modules corresponding one-to-one with each winding of the high-frequency transformer; each Boost module contains a parallel-connected switching transistor half-bridge structure and a capacitor half-bridge structure; the midpoint of the switching transistor half-bridge structure is used to connect to the positive output terminal of the corresponding power generation module; the negative output terminal of the power generation module is connected to the emitter of the lower switching transistor in the corresponding switching transistor half-bridge structure; the capacitor half-bridge structures in each Boost module are connected in series to form a medium-voltage DC bus; the two ends of each winding in the high-frequency transformer are respectively connected to the midpoint of the switching transistor half-bridge structure and the midpoint of the capacitor half-bridge structure in the corresponding Boost module. This invention can achieve voltage equalization between series-connected Boost modules without relying on any control, has a simple structure, low losses, and low maintenance and construction costs.

Description

Technical Field

[0001] This invention relates to the field of power electronic transformer technology, and in particular to a high-frequency chain interconnected input distributed output series modular Boost topology and its control method. Background Technology

[0002] Against the backdrop of global energy transition, the increasing scarcity of traditional fossil fuels and the continued deterioration of the ecological environment are driving countries to accelerate the development of renewable energy. As a representative of clean energy, solar photovoltaic (PV) power generation has become a major force in new energy development due to its unique advantages. However, limited by the fluctuations in solar irradiance and the conversion efficiency of PV cells, PV cells not only have a wide range of output voltage variations but also exhibit significant power fluctuations. This makes the efficient collection and boosting of PV power and its safe grid connection a key research topic. Compared to traditional AC boosting schemes, medium-voltage DC collection technology demonstrates significant advantages: it avoids harmonic pollution and inverter oscillation, while improving system stability and energy efficiency.

[0003] In related technologies, most employ a series output structure to connect the corresponding Boost modules of each photovoltaic array to form a medium-voltage DC bus, thereby achieving safe grid connection of the photovoltaic array. However, the different output power of the photovoltaic arrays leads to unequal output voltages when the output currents of the series-connected Boost modules are equal, which in turn affects the safe and stable operation of the power grid. Therefore, a voltage equalization control method is needed to balance the output voltages of each Boost module.

[0004] Currently, to address the issue of uneven output voltage among Boost modules, some researchers employ a bidirectional buck-boost chain structure as the power balancing unit. This scheme utilizes two switching transistors and an inductor to form a bidirectional converter, achieving voltage balancing between adjacent sub-modules by adjusting the switch duty cycle. However, this structure requires a large number of switching devices and high-capacity inductors to construct the energy transfer path, which not only increases system complexity but also leads to greater control difficulty. Furthermore, due to the lack of soft-switching technology, the switching losses in this structure are quite prominent. Some scholars have developed a ring power balancing topology and its optimized control strategy. While this scheme achieves voltage balance control, it does not reduce the number of active switches in the system but instead increases the number of passive components, and its closed-loop control algorithm design is quite cumbersome. In addition, some research teams have proposed a three-port converter system, which can complete energy distribution between modules through a single power transfer, exhibiting good modularity. However, this scheme requires the configuration of an additional low-voltage DC bus, which will inevitably increase the system's construction and maintenance costs.

[0005] In summary, existing voltage balancing schemes generally suffer from drawbacks such as complex topology and control algorithms, high switching losses, and high construction and maintenance costs. Summary of the Invention

[0006] This invention provides a high-frequency chain interconnected input distributed output serial modular Boost topology and control method to solve the problems of complex voltage equalization schemes, large switching losses, and high construction and maintenance costs.

[0007] In a first aspect, embodiments of the present invention provide a high-frequency chain interconnected input distributed output serial modular Boost topology, including: a high-frequency transformer, and Boost modules corresponding one-to-one with each winding in the high-frequency transformer; Each Boost module contains a parallel-connected switch half-bridge structure and a capacitor half-bridge structure, and the lower switch in each switch half-bridge structure has a simultaneous conduction period. The midpoint of the switching transistor half-bridge structure is used to connect to the positive output terminal of the corresponding power generation module; The negative output terminal of the power generation module is connected to the emitter of the lower switching transistor in the corresponding half-bridge switching transistor structure. The capacitor half-bridge structures in each Boost module are connected in series to form a medium-voltage DC bus. The two ends of each winding in the high-frequency transformer are respectively connected to the midpoint of the switching transistor half-bridge structure in the corresponding Boost module and the midpoint of the capacitor half-bridge structure.

[0008] In one possible implementation, the lower switching transistors in each half-bridge structure are turned on synchronously.

[0009] In one possible implementation, the switching half-bridge structure further includes: an upper switching transistor; The collector of the upper switch is connected to the positive terminal of the corresponding capacitor half-bridge structure; The emitter of the upper switch is connected to the collector of the lower switch and one end of the corresponding winding in the high-frequency transformer. The emitter of the upper switch is also used to connect to the positive output terminal of the corresponding power generation module; The emitter of the lower switch is connected to the negative terminal of the corresponding capacitor half-bridge structure and the negative output terminal of the corresponding power generation module, respectively. The bases of both the upper and lower switching transistors are used for connecting external control devices.

[0010] In one possible implementation, the capacitor half-bridge structure includes an upper capacitor and a lower capacitor; The negative terminal of the upper capacitor is connected to the positive terminal of the lower capacitor and the other end of the corresponding winding in the high-frequency transformer. The positive terminal of the upper capacitor serves as the positive terminal of the capacitor half-bridge structure, and the negative terminal of the lower capacitor serves as the negative terminal of the capacitor half-bridge structure, both of which are connected to the corresponding switching transistor half-bridge structure. The positive terminal of the capacitor half-bridge structure is also connected to the negative terminal of the capacitor half-bridge structure in the previous Boost module; wherein, the positive terminal of the first capacitor half-bridge structure is the positive terminal of the medium-voltage DC bus, and the negative terminal of the last capacitor half-bridge structure is the negative terminal of the medium-voltage DC bus.

[0011] In one possible implementation, the capacitance values ​​of the upper capacitor and the lower capacitor are equal.

[0012] In one possible implementation, the Boost module further includes: a first inductor; The midpoint of the switching transistor half-bridge structure is connected to the positive output terminal of the corresponding power generation module via the first inductor.

[0013] In one possible implementation, each winding of the high-frequency transformer has leakage inductance, which is equivalent to a second inductance connected in series with the winding.

[0014] Secondly, embodiments of the present invention provide a control method applied to each Boost module in a high-frequency chain interconnected input-distributed output serial modular Boost topology as described in the first aspect or any possible implementation of the first aspect, comprising: The output voltage and output current of the power generation module are collected, and the reference voltage of the power generation module at the maximum power point is determined based on the output voltage and the output current. Based on the output voltage and the reference voltage, determine the reference current; The duty cycle signal is determined based on the reference current and the output current; The duty cycle signal is modulated to generate a first control signal and a second control signal; the first control signal and the second control signal are used to control the switching transistor half-bridge structure.

[0015] In one possible implementation, the first control signal and the second control signal are complementary control signals with a phase difference of 180°.

[0016] Thirdly, embodiments of the present invention provide a control device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the method described in the first aspect or any possible implementation thereof.

[0017] Compared to existing technologies, this invention connects different windings of the same high-frequency transformer at the midpoint of the switching transistor half-bridge structure and the capacitor half-bridge structure of each Boost module. This allows the voltage on each winding to characterize the output voltage of each Boost module. The windings of the high-frequency transformer act as a high-frequency chain, interconnecting the output terminals of each Boost module. When voltage imbalance occurs, the energy transfer characteristic between the windings of the high-frequency transformer is utilized to transfer the output voltage of each Boost module, thereby balancing their output voltages. Here, by limiting the simultaneous conduction period of each lower switching transistor, the energy transfer path between Boost modules can be prevented from being blocked, ensuring smooth energy transfer. In essence, each Boost module is equivalently connected in parallel after isolation by the high-frequency transformer windings, and is in a mutually clamped state, thus achieving voltage balancing without relying on any control. Compared to other voltage balancing schemes, this invention achieves voltage balancing using only a high-frequency transformer, resulting in a simpler structure, lower losses, higher efficiency, and lower maintenance and construction costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the high-frequency chain interconnected input distributed output serial modular Boost topology and control method provided in the embodiments of the present invention; Figure 2 This is a waveform diagram of the control signals of the upper and lower switching transistors in each switching transistor half-bridge structure provided in the embodiments of the present invention; Figure 3 This is a schematic diagram of the equivalent structure of the high-frequency chain interconnected input distributed output serial modular Boost topology and control method provided in the embodiments of the present invention; Figure 4 This is a schematic diagram of the energy balance path when the lower switch is turned on, provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the energy balance path when the upper switch is turned on, provided in an embodiment of the present invention; Figure 6 This is a flowchart illustrating the implementation of the control method provided in this embodiment of the invention; Figure 7 This is a schematic diagram illustrating the principle of the control method provided in the embodiments of the present invention; Figure 8 This is a schematic diagram of the control device provided in an embodiment of the present invention. Detailed Implementation

[0019] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0020] In related technologies, most employ a series output structure to connect the corresponding Boost modules of each photovoltaic array to form a medium-voltage DC bus, thereby achieving safe grid connection of the photovoltaic array. However, this series output structure suffers from the problem of uneven output voltage among the Boost modules.

[0021] Currently, most solutions address the aforementioned output voltage imbalance by using control algorithms to adjust the duty cycle, employing ring power topologies, or configuring additional low-voltage DC buses. However, these solutions generally suffer from drawbacks such as complex topologies and control algorithms, high switching losses, and high construction and maintenance costs.

[0022] To simplify voltage balancing schemes, reduce switching losses, and lower construction and maintenance costs, this invention provides a high-frequency chain interconnected input-distributed output series modular Boost topology. By connecting different windings of the same high-frequency transformer at the midpoint of the switching transistor half-bridge and capacitor half-bridge structures of each Boost module, the energy transfer characteristic between the windings of the high-frequency transformer is utilized to transfer the output voltage of each Boost module, thereby balancing their output voltages. Essentially, each Boost module is equivalently connected in parallel after isolation via the high-frequency transformer windings, and is in a mutually clamped state, thus achieving voltage balancing without relying on any control. Compared to other voltage balancing schemes, this invention achieves voltage balancing using only a high-frequency transformer, resulting in a simpler structure, lower losses, higher efficiency, and lower maintenance and construction costs.

[0023] Figure 1 This is a schematic diagram of a high-frequency chain interconnected input-distributed output serial modular Boost topology provided in an embodiment of the present invention. (See diagram below.) Figure 1 As shown, the above-mentioned high-frequency chain interconnected input distributed output serial modular Boost topology includes: a high-frequency transformer 11, and Boost modules 12 corresponding one-to-one with each winding N in the high-frequency transformer.

[0024] Each Boost module 12 contains a parallel-connected switch half-bridge structure 121 and a capacitor half-bridge structure 122, and the lower switch S2 in each switch half-bridge structure 121 has a simultaneous conduction period. The midpoint of the switching transistor half-bridge structure 121 is used to connect to the positive output terminal of the corresponding power generation module 13; The negative output terminal of the power generation module 13 is connected to the emitter of the lower switch S2 in the corresponding switch half-bridge structure 121; The capacitor half-bridge structure 122 in each Boost module 12 is connected in series to form a medium-voltage DC bus; Figure 1 MVDC+ is the positive terminal of the medium-voltage DC bus, and MVDC- is the negative terminal of the medium-voltage DC bus. The two ends of each winding in the high-frequency transformer 11 are respectively connected to the midpoint of the switching half-bridge structure 121 and the midpoint of the capacitor half-bridge structure 122 in the corresponding Boost module 12.

[0025] The aforementioned power generation module 13 is a photovoltaic array. Considering that wind power generation also suffers from the aforementioned voltage imbalance problem, the aforementioned power generation module 13 can also be a wind power generation module.

[0026] In this embodiment of the invention, the two ends of each capacitor half-bridge structure 122 are the output terminals of each Boost module 12. Based on this, this embodiment of the invention connects the two ends of each winding in the high-frequency transformer to the midpoint of the switching transistor half-bridge structure 121 and the midpoint of the capacitor half-bridge structure 122 in the corresponding Boost module, so that the voltage value (i.e., winding voltage) at the two ends of each winding can reflect the output voltage of the corresponding Boost module.

[0027] When the output voltages of the various Boost modules are unbalanced, the voltages of the windings will also deviate. In a high-frequency transformer, energy can be transferred between the windings. When the voltages of the windings are unbalanced, the higher winding voltage can be coupled to the core T and then transferred to the other windings via the core T, ultimately achieving the goal of balancing the output voltages of the various Boost modules.

[0028] Essentially, the windings of the high-frequency transformer effectively isolate each Boost module, and by utilizing the energy transfer capability between the windings, the output voltage of each Boost module is balanced. This embodiment of the invention uses a high-frequency transformer to achieve a parallel effect (equal output voltage for each Boost module) by connecting the series-connected Boost modules, effectively achieving an equivalent parallel connection of the Boost modules.

[0029] Here, the lower switch S2 in the switching half-bridge structure 121 is used to provide an energy transmission path. By limiting the simultaneous conduction period of the lower switch S2 in each switching half-bridge structure 121, this embodiment of the invention can ensure that the energy transmission path between different Boost modules is unobstructed, so as to realize energy transmission.

[0030] Optionally, the lower switching transistors in each half-bridge structure are turned on simultaneously.

[0031] See Figure 2 , Figure 2 The diagram shows the waveforms of the control signals for the upper and lower switches in each half-bridge structure. Wherein, Pwm... s1-1 and Pwm s1-2 These represent the control signals for the upper and lower switches in the first half-bridge structure, respectively, Pwm. s2-1 and Pwm s2-2These represent the control signals for the upper and lower switches in the second half-bridge structure, respectively, Pwm. sn-1 and Pwm sn-2 These represent the control signals for the upper and lower switches in the nth half-bridge structure. D 1. D 2 and D n These represent the duty cycle of the control signal for each lower switching transistor. T s This indicates the signal period of each control signal. t Indicates time.

[0032] like Figure 2 As shown, synchronous turn-on of each lower switch means that the rising edges of the drive signals for each lower switch are synchronized, while the falling edges may be asynchronous. That is, they remain synchronously turned on but can use different duty cycles. Here, the duty cycle of each lower switch is determined by the corresponding control signal.

[0033] This invention, by limiting the synchronous conduction of the lower switching transistors in each half-bridge structure, forces the rising edges of the drive signals of all lower switching transistors to align, ensuring a known and controllable synchronous conduction period at the beginning of each switching cycle. At the beginning of each switching cycle, all lower switching transistors conduct simultaneously, guaranteeing continuous and stable energy transfer and achieving the fastest and most consistent equalization speed.

[0034] Furthermore, achieving "synchronous activation" requires only a simple global synchronization signal to trigger the rising edge of all drive signals. This is an open-loop, feedforward hardware strategy that requires no feedback, detection, or calculation. No control intervention is needed for the voltage equalization issue itself, ensuring efficient, simple, and reliable energy transfer paths between the boost modules.

[0035] The following section provides a detailed introduction to the high-frequency chain interconnected input-distributed output serial modular Boost topology.

[0036] Optional, see Figure 1 The switching half-bridge structure 121 also includes: an upper switching transistor S1.

[0037] The collector of the upper switch S1 is connected to the positive terminal of the corresponding capacitor half-bridge structure 122; The emitter of the upper switch S1 is connected to the collector of the lower switch S2 and one end of the corresponding winding in the high-frequency transformer 11. The emitter of the upper switch S1 is also used to connect to the positive output terminal of the corresponding power generation module 13; The emitter of the lower switch S2 is connected to the negative terminal of the corresponding capacitor half-bridge structure 122 and the negative output terminal of the corresponding power generation module 13, respectively. The bases of both the upper switch S1 and the lower switch S2 are used to connect to external control devices in order to receive control signals.

[0038] Optional, see Figure 1 The Boost module 12 also includes: a first inductor L1; The midpoint of the switching transistor half-bridge structure 121 is connected to the positive output terminal of the corresponding power generation module 13 via the first inductor L1.

[0039] Here, the first inductor L1 acts as an energy storage element, which achieves the purpose of boosting voltage by alternately storing and releasing energy.

[0040] Optionally, the capacitor half-bridge structure 122 includes: an upper capacitor C1 and a lower capacitor C2; The negative terminal of the upper capacitor C1 is connected to the positive terminal of the lower capacitor C2 and the other end of the corresponding winding in the high-frequency transformer 11. The positive terminal of the upper capacitor C1 serves as the positive terminal of the capacitor half-bridge structure 122, and the negative terminal of the lower capacitor C2 serves as the negative terminal of the capacitor half-bridge structure 122, both of which are connected to the corresponding switching transistor half-bridge structure 121. The positive terminal of the capacitor half-bridge structure 122 is also connected to the negative terminal of the capacitor half-bridge structure 122 in the previous Boost module; wherein, the positive terminal of the first capacitor half-bridge structure is the positive terminal MVDC+ of the medium voltage DC bus, and the negative terminal of the last capacitor half-bridge structure is the negative terminal MVDC- of the medium voltage DC bus.

[0041] This invention utilizes a first inductor, a switching transistor half-bridge structure, and a capacitor half-bridge structure to construct a typical non-isolated Boost topology. Compared to isolated dual active bridge (DAB) converter circuits, the non-isolated Boost topology has fewer switches, a simpler structure, lower losses, and higher efficiency.

[0042] In the above non-isolated Boost topology, when the lower switch S2 is turned on, the energy of the power generation module 13 is stored in the first inductor L1. When the lower switch S2 is turned off, the energy in the first inductor is released to capacitor C1 and lower capacitor C2 through the upper switch S1, thus achieving voltage boost. The voltage between the positive terminal of the upper capacitor and the negative terminal of the lower capacitor is the output voltage of the Boost module.

[0043] This invention, by connecting a high-frequency transformer winding to the midpoints of the upper and lower diodes and the upper and lower capacitors, allows the voltage between these two midpoints to be reflected in the high-frequency transformer windings. Essentially, the voltage amplitude between the two midpoints is the same as the voltage across the lower capacitor. In other words, the amplitude of the high-frequency transformer winding voltage is the same as the voltage across the lower capacitor, thus reflecting the output voltage of the Boost module.

[0044] Here, the output voltage of the Boost module can be determined based on the capacitance values ​​of the upper and lower capacitors, as well as the voltage value of the lower capacitor. Specifically, the product of the capacitance ratio of the upper and lower capacitors and the voltage value of the lower capacitor is the voltage value of the upper capacitor. The sum of the voltage values ​​of the upper and lower capacitors is the output voltage of the Boost module.

[0045] In this embodiment of the invention, by limiting the capacitance ratio of the upper and lower capacitors in each capacitor half-bridge structure to be the same, the output voltage of each Boost module can be balanced when the voltage of each winding is balanced, so as to avoid the situation where the voltage of each winding is balanced, but the output voltage of each Boost module is not balanced.

[0046] Optionally, the capacitance values ​​of the upper capacitor C1 and the lower capacitor C2 are equal.

[0047] When the capacitance values ​​of the upper capacitor C1 and the lower capacitor C2 are equal, the voltage of each winding is half of the output voltage of each Boost module. By balancing the voltage of each winding, the output voltage of each Boost module can be balanced. Furthermore, by setting the capacitance values ​​of the upper and lower capacitors to be equal, the upper and lower capacitors can be made to evenly bear the output voltage, avoiding the situation where a single capacitor bears too high a voltage, which could lead to capacitor breakdown.

[0048] This invention utilizes the winding voltage to reflect the output voltage of the Boost module, and leverages the energy transfer characteristics between the windings of the high-frequency transformer to achieve the transfer of output voltage between each Boost module, thereby balancing the output voltage between the Boost modules.

[0049] Optional, see Figure 3 Each winding of a high-frequency transformer has leakage inductance, which can be equivalent to a second inductance L2 connected in series with the winding.

[0050] Understandably, due to the coupling characteristics of high-frequency transformers, each winding of a high-frequency transformer has leakage inductance. In conventional technical solutions, leakage inductance, as a parasitic parameter, usually needs to be minimized to avoid affecting the circuit topology performance. However, in this embodiment of the invention, the leakage inductance can be equivalent to a second inductor L2 connected in series with the winding. During the energy equalization process between any two Boost modules, the value of the second inductor directly determines the slope of the current rise. Under the same voltage difference (i.e., the difference in output voltage between the two Boost modules), the larger the value of the second inductor, the slower the current rise rate and the smaller the peak current, thereby effectively suppressing the instantaneous stress on the switching transistor and transformer winding, and improving system reliability; conversely, the smaller the inductance value, the faster the equalization speed, but the peak current increases accordingly.

[0051] The value of the second inductor is chosen to balance the speed and current stress. For example, the inductance value of the second inductor can be in the range of 1~10μH to achieve the best balance between dynamic response and device safety.

[0052] Next, combined Figure 4 and Figure 5 The energy transfer paths between the various Boost modules are described.

[0053] When the output voltage of the i-th Boost module is greater than the output voltage of the j-th Boost module, see [reference needed]. Figure 4 When the lower switch is turned on, the current flows out from the positive terminal of the lower capacitor C2,i of the i-th Boost module, through the winding, the second inductor L2,i, and the lower switch S2,i, and returns to the negative terminal of the lower capacitor C2,i, forming a current loop.

[0054] The voltage in the winding is coupled to the j-th winding through the iron core T. The current flows from the j-th winding through the lower capacitor C2,j, the lower switch S2,j, and the second inductor L2,j back to the j-th winding, forming a current loop. This charges the lower capacitor C2,j, increases the voltage value of the lower capacitor C2,j, and thus increases the output voltage of the j-th Boost module.

[0055] See Figure 5 When the upper switch is turned on, the current flows out from the positive terminal of the upper capacitor C1,i of the i-th Boost module, through the upper switch S1,i, the second inductor L2,i, and the winding, and returns to the negative terminal of the upper capacitor C1,i, forming a current loop.

[0056] The voltage in the winding is coupled through the iron core T in the j-th winding. The current flows from the j-th winding through the second inductor L2,j, the upper switch S1,j and the upper capacitor C1,j back to the j-th winding, forming a current loop. This charges the upper capacitor C1,j, increases the voltage value of the upper capacitor C1,j, and thus increases the output voltage of the j-th Boost module.

[0057] When the output voltage of the i-th Boost module is greater than the output voltage of the j-th Boost module, energy transfer continues between the i-th Boost module and the j-th Boost module during the conduction of the upper and lower switches until the output voltage of the i-th Boost module equals the output voltage of the j-th Boost module.

[0058] The above description details the energy balancing process between Boost modules using only the i-th and j-th Boost modules as examples. The energy balancing process between all Boost modules is the same as described above and will not be repeated here. Boost modules with output voltage deviations all transfer energy through the above energy balancing process until the output voltages of all Boost modules are the same.

[0059] Compared to existing technologies, this invention connects different windings of the same high-frequency transformer at the midpoint of the switching transistor half-bridge structure and the capacitor half-bridge structure of each Boost module. This allows the voltage on each winding to characterize the output voltage of each Boost module. The windings of the high-frequency transformer act as a high-frequency chain, interconnecting the output terminals of each Boost module. When voltage imbalance occurs, the energy transfer characteristic between the windings of the high-frequency transformer is utilized to transfer the output voltage of each Boost module, thereby balancing their output voltages. Here, by limiting the simultaneous conduction period of each lower switching transistor, the energy transfer path between Boost modules can be prevented from being blocked, ensuring smooth energy transfer. In essence, each Boost module is equivalently connected in parallel after isolation by the high-frequency transformer windings, and is in a mutually clamped state, thus achieving voltage balancing without relying on any control. Compared to other voltage balancing schemes, this invention achieves voltage balancing using only a high-frequency transformer, resulting in a simpler structure, lower losses, higher efficiency, and lower maintenance and construction costs.

[0060] See Figure 6 This invention also provides a control method applied to each Boost module in the above-described high-frequency chain interconnected input-distributed-output serial modular Boost topology. Details are as follows: Step 601: Collect the output voltage and output current of the power generation module, and determine the reference voltage of the power generation module at the maximum power point based on the output voltage and output current.

[0061] See Figure 7 Each Boost module can utilize the Maximum Power Point Tracking (MPPT) algorithm to determine the power output voltage V of the power generation module. pv and output current I pv Determine the reference voltage V of the power generation module at its maximum power point. pv * Here, the power generation module may include, but is not limited to, photovoltaic arrays and wind power generation modules.

[0062] Step 602: Determine the reference current based on the output voltage and the reference voltage.

[0063] See Figure 7The embodiments of the present invention can output voltage V pv and reference voltage V pv The input is fed into the voltage outer loop PI controller, which will output voltage V. pv and reference voltage V pv * Compare and output reference current I pv *

[0064] Step 603: Determine the duty cycle signal based on the reference current and the output current.

[0065] See Figure 7 In this embodiment of the invention, the reference current I can be used. pv * and output current I pv The input is fed into the inner current loop PI controller, which will then use the reference current I... pv * and output current I pv The comparison is performed, and the duty cycle signal D is output.

[0066] Step 604: Modulate the duty cycle signal to generate a first control signal and a second control signal. The first control signal and the second control signal are used to control the switching transistor half-bridge structure.

[0067] See Figure 7 The duty cycle signal D is converted into the first control signal PWM by the PWM modulator. S1 Second control signal PWM S2 The first control signal and the second control signal are respectively sent to the gates of the upper and lower switching transistors in the switching transistor half-bridge structure to control the upper and lower switching transistors.

[0068] Optionally, the first control signal and the second control signal are complementary control signals with a phase difference of 180°.

[0069] In this embodiment of the invention, by defining the first control signal and the second control signal as complementary control signals with a phase difference of 180°, the upper and lower switching transistors in each half-bridge structure can be controlled to switch alternately to achieve the purpose of boosting voltage.

[0070] In this embodiment of the invention, each Boost module can be controlled by the above-described control method to perform boost control, so that each Boost module performs boost control according to the output voltage and output current of the corresponding power generation module.

[0071] It should be noted that while the lower switching transistors in each Boost module are turned on synchronously (i.e., the rising edges of each second control signal are synchronized), this embodiment of the invention does not specifically limit the falling edge of each second control signal. Essentially, this means that this embodiment of the invention does not control the duty cycle of each second control signal (the duty cycle of each second control signal is determined by the output voltage and output current of the corresponding power generation module). That is, the lower switching transistors remain synchronously turned on, but different duty cycles can be used.

[0072] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0073] The following are device embodiments of the present invention. For details not described in detail, please refer to the corresponding method embodiments described above.

[0074] Figure 8 A schematic diagram of the control device provided in an embodiment of the present invention is shown. For ease of explanation, only the parts related to the embodiment of the present invention are shown, and are described in detail below: like Figure 8 As shown, the control device 8 includes: a data acquisition module 81 and a control module 82.

[0075] The acquisition module 81 is used to acquire the output voltage and output current of the power generation module, and determine the reference voltage of the power generation module at the maximum power point based on the output voltage and output current. Control module 82 is used for: Determine the reference current based on the output voltage and the reference voltage; The duty cycle signal is determined based on the reference current and the output current; The duty cycle signal is modulated to generate a first control signal and a second control signal; the first control signal and the second control signal are used to control the switching transistor half-bridge structure.

[0076] In one possible implementation, the first control signal and the second control signal are complementary control signals with a phase difference of 180°.

[0077] This invention also provides a control device, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the method described in the above method embodiments.

[0078] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not detailed or described in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Unless otherwise specified or in conflict with logic, the terminology and / or descriptions between different embodiments are consistent and can be referenced interchangeably. Technical features in different embodiments can be combined to form new embodiments based on their inherent logical relationships.

[0079] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A high-frequency chain interconnected input-distributed output serial modular Boost topology, characterized in that, include: A high-frequency transformer, and a Boost module corresponding to each winding in the high-frequency transformer; Each Boost module contains a parallel-connected switch half-bridge structure and a capacitor half-bridge structure, and the lower switch in each switch half-bridge structure has a simultaneous conduction period. The midpoint of the switching transistor half-bridge structure is used to connect to the positive output terminal of the corresponding power generation module; The negative output terminal of the power generation module is connected to the emitter of the lower switching transistor in the corresponding half-bridge switching transistor structure. The capacitor half-bridge structures in each Boost module are connected in series to form a medium-voltage DC bus. The two ends of each winding in the high-frequency transformer are respectively connected to the midpoint of the switching transistor half-bridge structure in the corresponding Boost module and the midpoint of the capacitor half-bridge structure. The switching half-bridge structure further includes: an upper switching transistor; The collector of the upper switch is connected to the positive terminal of the corresponding capacitor half-bridge structure; The emitter of the upper switch is connected to the collector of the lower switch and one end of the corresponding winding in the high-frequency transformer. The emitter of the upper switch is also used to connect to the positive output terminal of the corresponding power generation module; The emitter of the lower switch is connected to the negative terminal of the corresponding capacitor half-bridge structure and the negative output terminal of the corresponding power generation module, respectively. The bases of both the upper and lower switching transistors are used for connecting external control devices. The capacitor half-bridge structure includes: an upper capacitor and a lower capacitor; The negative terminal of the upper capacitor is connected to the positive terminal of the lower capacitor and the other end of the corresponding winding in the high-frequency transformer. The positive terminal of the upper capacitor serves as the positive terminal of the capacitor half-bridge structure, and the negative terminal of the lower capacitor serves as the negative terminal of the capacitor half-bridge structure, both of which are connected to the corresponding switching transistor half-bridge structure. The positive terminal of the capacitor half-bridge structure is also connected to the negative terminal of the capacitor half-bridge structure in the previous Boost module; wherein, the positive terminal of the first capacitor half-bridge structure is the positive terminal of the medium-voltage DC bus, and the negative terminal of the last capacitor half-bridge structure is the negative terminal of the medium-voltage DC bus.

2. The high-frequency chain interconnected input-distributed output serial modular Boost topology according to claim 1, characterized in that, The lower switching transistors in each half-bridge structure are turned on synchronously.

3. The high-frequency chain interconnected input-distributed output serial modular Boost topology according to claim 1, characterized in that, The upper capacitor and the lower capacitor have the same capacitance value.

4. The high-frequency chain interconnected input-distributed output serial modular Boost topology according to claim 1 or 2, characterized in that, The Boost module further includes: a first inductor; The midpoint of the switching transistor half-bridge structure is connected to the positive output terminal of the corresponding power generation module via the first inductor.

5. The high-frequency chain interconnected input-distributed output serial modular Boost topology according to claim 1 or 2, characterized in that, Each winding of the high-frequency transformer has leakage inductance, which is equivalent to a second inductance connected in series with the winding.

6. A control method applied to each Boost module in the high-frequency chain interconnected input-distributed output serial modular Boost topology according to any one of claims 1-5, characterized in that, include: The output voltage and output current of the power generation module are collected, and the reference voltage of the power generation module at the maximum power point is determined based on the output voltage and the output current. Based on the output voltage and the reference voltage, determine the reference current; The duty cycle signal is determined based on the reference current and the output current; The duty cycle signal is modulated to generate a first control signal and a second control signal; The first control signal and the second control signal are used to control the switching transistor half-bridge structure.

7. The control method according to claim 6, characterized in that, The first control signal and the second control signal are complementary control signals with a phase difference of 180°.

8. A control device, characterized in that, It includes a memory and a processor, the memory storing a computer program, and the processor executing the computer program to implement the method as described in any one of claims 6 to 7.

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