Electric energy conversion system based on renewable energy sources

Abstract

The invention provides an electric energy conversion system based on renewable energy sources. The electric energy conversion system comprises an integrated three-port direct current-direct current converter, a renewable energy source unit, a battery unit and a direct current bus, the integrated three-port DC-DC converter is provided with a first port, a second port, a third port and a controller. The renewable energy unit is connected with a first port of the integrated three-port direct current-direct current converter, the battery unit is connected with a second port of the integrated three-port direct current-direct current converter, and the direct current bus is connected with a third port of the integrated three-port direct current-direct current converter; the controller of the integrated three-port DC-DC converter is used for controlling the power flow of the electric energy according to the phase displacement angle between the primary side equipment and the secondary side equipment, so that the bidirectional flow of the electric energy can be realized, and the functionality and the electric energy conversion efficiency of the electric energy conversion system based on the renewable energy sources are improved.

Description

Technical Field

[0001] This application relates to the technical field of power conversion, and more specifically to a power conversion system based on renewable energy. Background Technology

[0002] With the increasing prevalence of grid-connected renewable energy generation, feed-in tariffs (FiT) are expected to decrease, while conventional electricity prices will rise. Consequently, the use of renewable energy systems (RES) with battery backup is anticipated to increase. Furthermore, to alleviate the challenges of connecting a large number of new energy generation units to the grid, the use of RES with battery backup systems will also increase.

[0003] However, in the existing technology, to supply power to the DC bus with renewable energy, it is necessary to establish a renewable energy power conversion system; to charge the battery cells with renewable energy, it is necessary to establish another renewable energy power conversion system; moreover, the existing power conversion systems have very low power conversion efficiency. Therefore, the existing renewable energy power conversion systems have technical defects of single function and low power conversion efficiency. Summary of the Invention

[0004] The purpose of this application is to provide a power conversion system based on renewable energy that can overcome the shortcomings and deficiencies of the prior art.

[0005] The first aspect of this application provides a renewable energy-based power conversion system, including: an integrated three-port DC-DC converter, a renewable energy unit, a battery unit, and a DC bus; wherein the integrated three-port DC-DC converter is provided with a first port, a second port, a third port, and a controller; The renewable energy unit is connected to the first port of the integrated three-port DC-DC converter, the battery unit is connected to the second port of the integrated three-port DC-DC converter, and the DC bus is connected to the third port of the integrated three-port DC-DC converter. The controller of the integrated three-port DC-DC converter is used to control the power flow of electrical energy based on the phase shift angle between the primary and secondary devices.

[0006] Furthermore, the integrated three-port DC-DC converter includes an active bridge, the topology of which is a half-bridge circuit and a full-bridge circuit, or a three-phase half-bridge circuit.

[0007] Furthermore, the controller of the integrated three-port DC-DC converter is used to perform the following steps: Based on the control duty cycle of the current output by the renewable energy unit via the first port, the phase shift angles of the second and third ports, and a preset phase shift angle transfer function, the power flow output to the DC bus via the third port is controlled.

[0008] Furthermore, the control of the power flow output to the DC bus via the third port is achieved through the following formula: ;in, The power flow output to the DC bus via the third port is φ, the phase shift angle is D, and the control duty cycle is D.

[0009] Furthermore, the controller of the integrated three-port DC-DC converter is used to perform the following steps: The power of the renewable energy unit is determined as the first power, the power of the battery unit is determined as the second power, and the power of the DC bus is determined as the third power. Based on the first power, the second power, and the third power, an operating mode is obtained to drive the integrated three-port DC-DC converter to operate according to the operating mode.

[0010] Further, the step of obtaining the operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the first working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the first operating mode, including: outputting the electrical energy output by the renewable energy unit to the battery unit and the DC bus, thereby charging the battery unit, providing electrical energy to the DC bus, and determining the charging current of the battery unit or the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target.

[0011] Further, the step of obtaining the operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the second working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the second operating mode, including: outputting the electrical energy output by the renewable energy unit and the battery unit to the DC bus, thereby providing electrical energy to the DC bus, and determining the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target.

[0012] Further, the step of obtaining the operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the third working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the third operating mode, including: outputting the electrical energy output from the renewable energy unit and the DC bus to the battery unit, and determining the charging current of the battery unit as the control target to obtain the phase shift angle corresponding to the control target.

[0013] Further, the step of obtaining the operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when and When =0, it is determined to be the fourth working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the fourth operating mode, including: outputting the electrical energy output by the renewable energy unit to the DC bus, and determining the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target.

[0014] Further, the step of obtaining the operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when and When =0, it is determined to be the fifth working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the fifth operating mode, including: outputting the electrical energy output by the battery cell to the DC bus, and determining the discharge current of the battery cell as the control target to obtain the phase shift angle corresponding to the control target.

[0015] Compared to existing technologies, the integrated three-port DC-DC converter of this application includes a first port, a second port, a third port, and a controller. The renewable energy unit is connected to the first port of the integrated three-port DC-DC converter, the battery unit is connected to the second port of the integrated three-port DC-DC converter, and the DC bus is connected to the third port of the integrated three-port DC-DC converter. The controller of the integrated three-port DC-DC converter is used to control the power flow of electrical energy according to the phase shift angle between the primary and secondary devices. This achieves bidirectional flow of electrical energy for the battery unit and / or the DC bus through phase control between different ports, improving the functionality and conversion efficiency of the renewable energy-based power conversion system.

[0016] To provide a clearer understanding of this application, the specific embodiments of this application will be described below in conjunction with the accompanying drawings. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a renewable energy-based power conversion system according to an embodiment of this application.

[0018] Figure 2 This is a circuit diagram of a half-bridge circuit and a full-bridge circuit of a renewable energy-based power conversion system according to an embodiment of this application.

[0019] Figure 3 This is a circuit diagram of a three-phase half-bridge circuit of a renewable energy-based power conversion system according to an embodiment of this application.

[0020] Figure 4 This is a schematic diagram of the converter operating area of ​​a renewable energy-based power conversion system according to an embodiment of this application.

[0021] Figure 5 This is a schematic diagram of the primary and secondary voltage waveforms, phase shift angle, and duty cycle of a dual active bridge DC-DC converter in a renewable energy-based power conversion system according to an embodiment of this application.

[0022] Figure 6 This is a control block diagram of a renewable energy-based power conversion system according to an embodiment of this application.

[0023] Figure 7This is a circuit diagram of a boost circuit for a renewable energy-based power conversion system according to an embodiment of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0025] It should be understood that the described embodiments are merely some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0026] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, it should be understood that the terms "first," "second," "third," etc., are used only to distinguish similar objects and are not necessarily used to describe a specific order or sequence, nor should they be construed as indicating or implying relative importance. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. The singular forms "a," "the," and "the" used in this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. The word "if" as used herein can be interpreted as "when," "when," or "in response to determination."

[0027] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0028] Please see Figure 1 This is a schematic diagram of a module of a renewable energy-based power conversion system according to an embodiment of this application, including: An integrated three-port DC-DC converter, a renewable energy unit, a battery unit, and a DC bus; wherein the integrated three-port DC-DC converter is provided with a first port, a second port, a third port, and a controller.

[0029] The first port of an integrated three-port DC-DC converter can be referred to as port 1, the second port as port 2, and the third port as port 3.

[0030] The renewable energy unit is connected to the first port of the integrated three-port DC-DC converter, the battery unit is connected to the second port of the integrated three-port DC-DC converter, and the DC bus is connected to the third port of the integrated three-port DC-DC converter.

[0031] The renewable energy unit can be simply described as a renewable energy source, including photovoltaic panels, fuel cells, wind turbines, and other renewable energy sources. For example, the same maximum power point tracking (MPPT) control method can be applied. Before being connected to the first port, the energy generated by the wind turbine is rectified into DC output by an AC-DC converter.

[0032] The controller of the integrated three-port DC-DC converter is used to control the power flow of electrical energy based on the phase shift angle between the primary and secondary devices.

[0033] Specifically, in this embodiment, one port on the low-voltage side of the integrated three-port DC-DC converter is designed as a current source port, and RES is connected to this port to meet the requirements of Maximum Power Point Tracking (MPPT) and voltage variation. Due to its small voltage variation, the battery pack is connected to the low-voltage side (LVS) DC link. The DC distributed bus is connected to the high-voltage side (HVS) port, and electrical isolation is achieved through a high-frequency transformer. As shown in Figure 3, the three-terminal integrated DC-DC converter can be a dual half-bridge, dual full-bridge, or dual three-phase bridge converter.

[0034] Please see Figure 2-3 In one feasible embodiment, the integrated three-port DC-DC converter includes an active bridge, the topology of which is a half-bridge circuit and a full-bridge circuit, or a three-phase half-bridge circuit.

[0035] The active bridge of the integrated three-port DC-DC converter can be a current-source dual-excitation bridge (DAB) converter to achieve bidirectional power flow and provide dielectric isolation through a high-frequency transformer, while matching the voltage levels between the low-voltage energy source and the high-voltage DC bus. The leakage inductance of the transformer acts as an energy storage element, used to transfer power between the two sides, and the power flow is mainly controlled by the phase shift angle φ. A DC inductor Ldc is connected to an energy port at the midpoint of the half-bridge leg of the LVS, while the duty cycle D is another control variable for adjusting the power distribution between the two ports of the LVS. When applying a PV (Photovoltaic Voltage) system on the DC bus, the converter is used to interface with the RES, battery unit (BU), and DC bus or load. The BU is connected to the LVS DC link. The voltage of the battery unit varies slowly with different SOCs, so the primary-side DC link voltage can be considered almost constant. The RES is connected to the current source port. Due to different input power conditions, the output voltage and current of the RES vary widely. A DC inductor and primary-side switch are used to boost the RES voltage and achieve maximum power point tracking (MPPT) through duty cycle control. With the help of the DC inductor, zero-voltage switching (ZVS) is guaranteed in all operating modes, even as the battery cell voltage varies with different SOCs.

[0036] In one feasible embodiment, the controller of the integrated three-port DC-DC converter is used to perform the following steps: Based on the control duty cycle of the current output by the renewable energy unit via the first port, the phase shift angles of the second and third ports, and a preset phase shift angle transfer function, the power flow output to the DC bus via the third port is controlled.

[0037] The preset phase shift transfer function may include: For a half-bridge circuit, the power output at the third port is a function of the phase shift angle that satisfies:

[0038] For a full-bridge circuit, the power output function satisfies:

[0039] For a three-phase half-bridge circuit, the power output function satisfies:

[0040] Where V1 is the input voltage at port 1, V3 is the DC bus voltage at port 3, and D is the duty cycle. is the switching phase shift angle between the bridge arm at port 1 and the bridge arm at port 3, and n is the turns ratio of the transformer windings at port 3 and port 1. , It is the switching frequency of the power device. This refers to the leakage inductance of the transformer at port 1. Specifically, for different types of DAB converters, the same power flow control can be achieved through the phase shift angle between the primary and secondary devices. For port 1 with a boost unit, the duty cycle can be used to further control the constant voltage of the DC bus voltage 1. Since the DC bus voltages at different ports can remain matched, even if the RES voltage varies over a wide voltage range, and the battery voltage varies over a small voltage range with different states of charge (SOC), zero-voltage switching (ZVS) technology can be guaranteed in different operating modes, thereby improving system efficiency and reliability. The proposed three-terminal converter's power flow control can be decoupled over a wide voltage operating range; therefore, it can be used as an upgraded version of a dual-active-bridge DC-DC converter. Please see Figure 4 , Figure 4 The operating regions of different (φ,D) converters are shown, with the shaded areas representing those recommended for practical applications. Figure 4 In this context, maximum power point tracking (MPPT) control of renewable energy sources such as photovoltaic panels can be achieved through the duty cycle D of the current-source converter connected to control port 1. Here, the duty cycle D is the percentage of the switching time of the lower transistor within one switching cycle Ts, i.e.: ;like Figure 5 As shown, the phase shift angle φ is the phase difference between the corresponding half-bridge midpoint voltages Vac and Vrs between port 2 and port 3 within one switching cycle.

[0041] like Figure 6 As shown, Gid_boost(s) is the transfer function between the output current of the photovoltaic panel at port 1 and the control variable duty cycle D, while Giφ_DAB(s) is the transfer function between the input current at port 2 and the control variable phase shift angle φ. By controlling the duty cycle and phase shift angle, it is possible to achieve tracking control of the maximum output power of the photovoltaic panel and control of the battery charging and discharging power.

[0042] In a feasible embodiment, the modulation strategy for the three terminals is phase shift plus duty cycle, thus the converter's operating range is a two-dimensional region of (φ, D), as shown in Figure 4. The power flow between the LVS and HVS will change depending on different combinations of duty cycle and phase shift angle. In practical applications, to ensure efficient converter operation, the duty cycle is limited to between 1 / 3 and 2 / 3, and the phase shift angle should be less than π / 3 to reduce reactive power loss. The power flow equation for port 3 is a function of φ and D: Therefore, the control of the power flow output to the DC bus via the third port is achieved by the following formula: ;in, The power flow output to the DC bus via the third port is φ, the phase shift angle is D, and the control duty cycle is D. is the phase shift angle between the bridge arm of port 1 and the bridge arm of port 3, and n is the turns ratio of the transformer windings at port 3 and port 1. , It is the switching frequency of the power device. It is the leakage inductance of the transformer at port 1.

[0043] In one feasible embodiment, the controller of the integrated three-port DC-DC converter is used to perform the following steps: The power of the renewable energy unit is determined as the first power, the power of the battery unit is determined as the second power, and the power of the DC bus is determined as the third power. Due to the additional power flow combination of the integrated three-port DC-DC converter, the integrated three-port DC-DC converter has five operating modes, as shown in the table below: ; Power meets .

[0044] Based on the first power, the second power, and the third power, an operating mode is obtained to drive the integrated three-port DC-DC converter to operate according to the operating mode.

[0045] In a feasible embodiment, the step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the first working mode; among which, For the first power, This is the second power. The third power source drives the integrated three-port DC-DC converter to operate according to the first operating mode, including: outputting the electrical energy output from the renewable energy unit to the battery unit and the DC bus, thereby charging the battery unit and providing electrical energy to the DC bus, and determining the charging current of the battery unit or the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target. The phase shift angle is obtained by the following formula: Specifically, in the first operating mode, the renewable energy power is high, and the renewable energy unit (RES) can simultaneously provide power to the DC bus and charge the battery unit. In this mode, the function of the battery unit (BU) is to store excess energy. The power control target in the first operating mode can be the battery charging current Ibat or a predetermined DC bus current Ibus. If Ibus is selected as the control target, the relationship φ related to Ibus can be derived.

[0046] In a feasible embodiment, the step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the second working mode; among which, For the first power, This is the second power. The third power source drives the integrated three-port DC-DC converter to operate according to the second operating mode, including: outputting the electrical energy from the renewable energy unit and the battery unit to the DC bus, thereby providing power to the DC bus, and determining a predetermined DC bus current as a control target to obtain the phase shift angle corresponding to the control target. The phase shift angle is obtained by the following formula: Specifically, in the second operating mode, renewable energy power is insufficient, so the renewable energy unit (RES) and battery unit (BU) will work together to provide power to meet the predetermined DC bus load demand. The battery unit (BU) in this mode serves as the energy source to support the DC bus load. In this mode, only the bus current Ibus can be controlled, therefore φ is derived. In a feasible embodiment, the step of obtaining the operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating model includes: when... At that time, it was determined to be the third working mode; among which, For the first power, This is the second power. The third power source drives the integrated three-port DC-DC converter to operate according to the third operating mode, including: outputting the electrical energy from the renewable energy unit and the DC bus to the battery unit, and determining the charging current of the battery unit as the control target to obtain the phase shift angle corresponding to the control target. The phase shift angle is obtained by the following formula: In the third operating mode, the battery's state of charge (SOC) is low, and the renewable energy unit (RES) and DC bus provide power to charge the battery cells. Because charging times are often long, this mode may last for an extended period. In this case, controlling the battery's charging current Ibat is optimal. Based on this requirement, the related parameter φ can be derived.

[0047] In a feasible embodiment, the step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when and When =0, it is determined to be the fourth working mode; among which, For the first power, This is the second power. The third power; Driving the integrated three-port DC-DC converter to operate according to the fourth operating mode includes: outputting the electrical energy output from the renewable energy unit to the DC bus, and determining a predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target. The phase shift angle is obtained by the following formula: In the fourth operating mode, renewable energy power is sufficient to meet the load requirements of the DC bus. In this mode, the battery cells are stationary and do not charge or discharge. Therefore, the phase shift angle φ can be determined based on the predetermined DC bus current Ibus.

[0048] In a feasible embodiment, the step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when and When =0, it is determined to be the fifth working mode; among which, For the first power, This is the second power. The third power source drives the integrated three-port DC-DC converter to operate according to the fifth operating mode, including: outputting the electrical energy output from the battery cell to the DC bus, and determining the discharge current of the battery cell as the control target to obtain the phase shift angle corresponding to the control target. The phase shift angle is obtained by the following formula: In the fifth mode, renewable energy is insufficient to support the load. The battery supplies power to the DC bus. In this mode, the battery discharge current Ibat can be used to control the converter and determine the phase shift angle φ.

[0049] When designing the controller, several practical factors need to be considered, such as the losses of switching devices, parameter variations of inductors and capacitors, and voltage and current fluctuations in the power supply. To improve the converter's dynamic response and interference suppression capabilities, a feedforward control strategy can be employed. To ensure the safe and stable operation of the converter, several protection functions also need to be considered, such as overcurrent protection, overvoltage protection, and temperature protection.

[0050] like Figure 6 As shown, to better understand and describe the control strategy of an integrated three-port DC-DC converter, a control block diagram based on a mathematical model is established. In practical applications, this model can be used to simulate and optimize the control strategy to achieve better system performance.

[0051] Furthermore, considering that the power flow of an integrated three-port DC-DC converter is primarily related to the phase shift angle φ, and less so to D, port 1 of this three-port converter can be considered as a boost circuit with duty cycle control, connected to a DAB converter with phase shift angle control, such as... Figure 7 As shown, it becomes a conventional two-stage DC-DC converter, with the controller including a boost controller and a fixed duty cycle DAB controller, which makes it easier to analyze the system's operating mode.

[0052] Compared to existing technologies, the integrated three-port DC-DC converter of this application includes a first port, a second port, a third port, and a controller. The renewable energy unit is connected to the first port of the integrated three-port DC-DC converter, the battery unit is connected to the second port of the integrated three-port DC-DC converter, and the DC bus is connected to the third port of the integrated three-port DC-DC converter. The controller of the integrated three-port DC-DC converter is used to control the power flow of electrical energy according to the phase shift angle between the primary and secondary devices. This achieves bidirectional flow of electrical energy for the battery unit and / or the DC bus through phase control between different ports, improving the functionality and conversion efficiency of the renewable energy-based power conversion system.

[0053] The device embodiments described above are merely illustrative. The components described as separate parts may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this application according to actual needs. Those skilled in the art can understand and implement this without any inventive effort.

[0054] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0055] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 The computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function selected in one or more boxes.

[0056] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function selected in one or more boxes.

[0057] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0058] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0059] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0060] It should also be noted that 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 process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0061] The above are merely embodiments of this application and are not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A power conversion system based on renewable energy, characterized in that, include: An integrated three-port DC-DC converter, a renewable energy unit, a battery unit, and a DC bus; wherein the integrated three-port DC-DC converter is provided with a first port, a second port, a third port, and a controller; The renewable energy unit is connected to the first port of the integrated three-port DC-DC converter, the battery unit is connected to the second port of the integrated three-port DC-DC converter, and the DC bus is connected to the third port of the integrated three-port DC-DC converter. The controller of the integrated three-port DC-DC converter is used to control the power flow of electrical energy based on the phase shift angle between the primary and secondary devices.

2. The renewable energy-based power conversion system according to claim 1, characterized in that: The integrated three-port DC-DC converter includes an active bridge, the topology of which is a half-bridge circuit and a full-bridge circuit, or a three-phase half-bridge circuit.

3. The renewable energy-based power conversion system according to claim 1, characterized in that, The controller of the integrated three-port DC-DC converter is used to perform the following steps: Based on the control duty cycle of the current output by the renewable energy unit via the first port, the phase shift angles of the second and third ports, and a preset phase shift angle transfer function, the power flow output to the DC bus via the third port is controlled.

4. The renewable energy-based power conversion system according to claim 3, characterized in that, The control of the power flow output to the DC bus via the third port is achieved by the following formula: in, The power flow output to the DC bus via the third port is φ, the phase shift angle is D, and the control duty cycle is D. is the phase shift angle between the bridge arm of port 1 and the bridge arm of port 3, and n is the turns ratio of the transformer windings at port 3 and port 1. , It is the switching frequency of the power device. It is the leakage inductance of the transformer at port 1.

5. The renewable energy-based power conversion system according to claim 1, characterized in that, The controller of the integrated three-port DC-DC converter is used to perform the following steps: The power of the renewable energy unit is determined as the first power, the power of the battery unit is determined as the second power, and the power of the DC bus is determined as the third power. Based on the first power, the second power, and the third power, an operating mode is obtained to drive the integrated three-port DC-DC converter to operate according to the operating mode.

6. The renewable energy-based power conversion system according to claim 5, characterized in that, The step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the first working mode; among which, For the first power, This is the second power. The third power; Driving the integrated three-port DC-DC converter to operate according to the first operating mode includes: outputting the electrical energy output by the renewable energy unit to the battery unit and the DC bus, thereby charging the battery unit, providing electrical energy to the DC bus, and determining the charging current of the battery unit or the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target.

7. The renewable energy-based power conversion system according to claim 5, characterized in that, The step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the second working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the second operating mode, including: outputting the electrical energy output by the renewable energy unit and the battery unit to the DC bus, thereby providing electrical energy to the DC bus, and determining the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target.

8. The renewable energy-based power conversion system according to claim 5, characterized in that, The step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when At that time, it was determined to be the third working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the third operating mode, including: outputting the electrical energy output from the renewable energy unit and the DC bus to the battery unit, and determining the charging current of the battery unit as the control target to obtain the phase shift angle corresponding to the control target.

9. The renewable energy-based power conversion system according to claim 5, characterized in that, The step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when and When =0, it is determined to be the fourth working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the fourth operating mode, including: outputting the electrical energy output by the renewable energy unit to the DC bus, and determining the predetermined DC bus current as the control target to obtain the phase shift angle corresponding to the control target.

10. The renewable energy-based power conversion system according to claim 5, characterized in that, The step of obtaining an operating mode based on the first power, the second power, and the third power to drive the integrated three-port DC-DC converter to operate according to the operating mode includes: when and When =0, it is determined to be the fifth working mode; among which, For the first power, This is the second power. The third power is used to drive the integrated three-port DC-DC converter to operate according to the fifth operating mode, including: outputting the electrical energy output by the battery cell to the DC bus, and determining the discharge current of the battery cell as the control target to obtain the phase shift angle corresponding to the control target.

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