Port-multiplexing multi-directional high step-up and step-down ratio three-port non-isolated direct-current converter

Abstract

The invention discloses a multidirectional high step-up and step-down ratio three-port non-isolated direct-current converter capable of multiplexing ports, and belongs to the field of power electronics. A traditional load port is replaced by a multiplexing port, and the number of ports of the converter is increased. When the photovoltaic power generation power is insufficient or the photovoltaic power generation does not work, the energy storage module connected with the energy storage input and output port can be charged through the multiplexing port, so that the energy storage module can be prevented from being over-discharged, more reserve energy can be provided for the system, an additional energy storage charging device is prevented from being added, and the energy management efficiency of the system is improved. Meanwhile, the converter has the wide gain characteristic of multi-directional high-boost and high-buck, is high in adaptability, can keep the output voltage stable when the input voltage fluctuation is large, adapts to loads, energy storage modules, direct-current power supplies and photovoltaic systems of different voltage levels, can efficiently operate under complex working conditions, ensures the reliability and stability of the system, and is suitable for large-scale popularization and application. And the requirements of various application scenes are met.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a multi-directional high step-down / step-down ratio three-port non-isolated direct current converter capable of port multiplexing. Background Art

[0002] The installed capacity of renewable energy such as photovoltaics continues to rise, but its volatility and intermittency remain the main bottleneck for large-scale application.

[0003] To solve the volatility problem of renewable energy, the rapid development of energy storage technology has provided important support, especially electrochemical energy storage technology. The integrated application of photovoltaic and energy storage systems (photovoltaic storage systems) plays an important role in improving energy utilization efficiency and enhancing the stability of power systems. As the core component of the photovoltaic storage system, the three-port DC converter can realize efficient energy exchange between photovoltaics, energy storage and loads, and provides a feasible solution to solve the power transmission and voltage stability problems in distributed energy systems.

[0004] Three-port DC converters are mainly divided into three-port isolated DC converters and three-port non-isolated DC converters. Three-port non-isolated DC converters are widely used due to their advantages such as simpler topology, higher power density and higher conversion efficiency. Existing three-port non-isolated DC converters mainly have the following problems.

[0005] First, most of the existing three-port non-isolated DC converters rely on a single working mode and cannot meet the power requirements in different environments, which limits the flexibility and applicability of the system. For example, the energy of the existing three-port non-isolated DC converter is usually obtained from the outside only through photovoltaic power generation. When the photovoltaic input power is insufficient, even if the load is not working, the energy storage module in the converter may face the risk of over-discharge; in addition, in the case of long-term low light or no light, the user needs to charge the energy storage module in advance, but the load port of the existing three-port non-isolated DC converter topology structure cannot realize the reverse transmission of energy, resulting in it being unable to charge the energy storage module inside the topology or realize fast charging when the light is insufficient, and an additional charging device must be equipped. Therefore, how to realize more power transmission modes from the topological structure without the need to equip additional charging devices is the problem that the present invention focuses on solving.

[0006] Secondly, although the three-port non-isolated DC converter has higher power density and higher conversion efficiency than the isolated converter, the current three-port non-isolated DC converter still faces bottlenecks in achieving a wide transformation ratio and cannot meet the demand for a wide transformation ratio in some photovoltaic storage systems. For example, in order to achieve a wide gain, the existing three-port non-isolated DC converter will adopt coupled inductors, switched capacitors and other solutions, which not only increases the volume of the converter and reduces the power density of the device, but also puts forward higher requirements on the production process; in addition, most of the existing three-port non-isolated DC converters can only work in boost mode, which greatly limits the voltage level of the energy storage module and the load, and the low-voltage port needs to be additionally incorporated into the buck circuit. Therefore, how to break through the existing topological structure limitations and propose a three-port non-isolated DC converter with a multi-directional high buck-boost ratio is a key problem that the present invention needs to solve.

[0007] Third, the traditional three-port non-isolated DC converter usually realizes multiple inputs through switches or series or parallel connection of multiple independent converters, which not only increases the complexity of the circuit, but also leads to an increase in the number of system components and an increase in cost. How to reduce the number of switch components of the three-port non-isolated DC converter while realizing port multiplexing and multi-directional high buck-boost ratio is another key problem to be solved by the present invention.

[0008] In summary, the existing three-port non-isolated DC converter has obvious deficiencies in multi-directional wide gain, working mode and system complexity, and its performance needs to be further optimized to meet the needs of the typical application scenario of the photovoltaic storage system. Summary of the invention

[0009] The present invention provides a multi-directional high step-down / step-down ratio three-port non-isolated DC converter capable of port multiplexing, so as to solve the problems of limited gain range, single working mode and overly complex topology of the existing three-port non-isolated DC converter.

[0010] The embodiment of the present invention provides a multi-directional high step-down ratio three-port non-isolated DC converter with port multiplexing, including: a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first diode D1, a second diode D2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a unidirectional input port V P , Energy storage input and output port V B and multiplexed port V DC ;

[0011] The unidirectional input port V P Connecting to a photovoltaic power generation port for converting light energy into electrical energy and providing input energy to a converter;

[0012] The energy storage input and output port V B Connecting an energy storage system to input or output energy to the converter;

[0013] The multiplexing port V DC Connecting a load or a DC power source to consume energy or provide energy input for the converter;

[0014] The unidirectional input port V P The positive electrode is connected to the anode of the first diode D1 and the anode of the second diode D2, and the unidirectional input port V P The negative pole is grounded and connected to the energy storage input output port V B The negative electrode of the first capacitor C1, the source of the seventh switch S7, and the second end of the second inductor L2 are connected;

[0015] The energy storage input and output port V B The positive electrode is connected to the first end of the first capacitor C1 and the source of the first switch S1, and the energy storage input and output port V B The negative electrode is grounded and connected to the second end of the first capacitor C1, the source of the seventh switch S7, and the second end of the second inductor L2;

[0016] The multiplexing port V DC The positive electrode is connected to the first end of the second capacitor C2 and the source of the fourth switch S4, and the multiplexing port V DC The negative electrode is connected to the second end of the second capacitor C2, the first end of the second inductor L2, the source of the sixth switch S4, and the source of the eighth switch S8;

[0017] The drain of the first switch S1 is connected to the drain of the second switch S2, and the source of the first switch S1 is connected to the first end of the first capacitor C1;

[0018] The source of the second switch S2 is connected to the first end of the first inductor L1 and the drain of the eighth switch S8;

[0019] The drain of the third switch S3 is connected to the drain of the fourth switch S4, and the source of the third switch S3 is connected to the second end of the first inductor L1, the source of the fifth switch S5, and the drain of the seventh switch S7;

[0020] The source of the fourth switch S4 is connected to the first end of the second capacitor C2;

[0021] The drain of the fifth switch S5 is connected to the cathode of the first diode D1, and the source of the fifth switch S5 is connected to the second end of the first inductor L1 and the drain of the seventh switch S7;

[0022] The drain of the sixth switch S6 is connected to the cathode of the second diode D2, and the source of the sixth switch S6 is connected to the source of the eighth switch S8, the first end of the second inductor L2, and the second end of the second capacitor C2;

[0023] The drain of the seventh switch S7 is grounded and connected to the second end of the first inductor L1, and the source of the seventh switch S7 is connected to the second end of the second capacitor C2 and the second end of the second inductor L2;

[0024] The drain of the eighth switch S8 is connected to the first end of the first inductor L1, and the source of the eighth switch S8 is connected to the first end of the second inductor L2 and the second end of the second capacitor C2;

[0025] The anode of the first diode D1 is connected to the anode of the second diode D2;

[0026] The second end of the first capacitor C1 is grounded and connected to the second end of the second inductor L2;

[0027] The second end of the second capacitor C2 is connected to the first end of the second inductor L2.

[0028] Optionally, in one embodiment of the present invention, the three-port non-isolated DC converter is used to implement seven operating modes, including: four single-input single-output operating modes, one single-input dual-output operating mode and two dual-input single-output operating modes.

[0029] Optionally, in one embodiment of the present invention, the seven operating modes of the three-port non-isolated DC converter are:

[0030] Single-input single-output mode SISO-1: The multiplexed port V DC Connect the load, the unidirectional input port V P No power is input to the system, the energy storage input output port V B Input power, supplying power to the load;

[0031] Single-input single-output mode SISO-2: The unidirectional input port does not input power to the system, and the multiplexed port V DC Connect to the DC power supply, input power to the converter, and provide the energy storage input and output port V B powered by;

[0032] Single-input single-output mode SISO-3: The energy storage input and output port V B does not participate in the converter energy exchange, the multiplexing port V DC Connect the load, the unidirectional input port V P Input power, supplying power to the load;

[0033] Single-input single-output mode SISO-4: The multiplexed port V DC The unidirectional input port V P Input power, for the energy storage input and output ports V B powered by;

[0034] Single-input dual-output mode SIDO: The multiplexed port V DC Connect the load, the unidirectional input port V P Input power, while the energy storage input and output ports V B and the multiplexed port V DC Power supply for connected loads;

[0035] Dual-input single-output mode DISO-1: The multiplexed port V DC Connect the load, the unidirectional input port V P and the energy storage input and output ports V B Commonly input power to the converter to supply power to the load;

[0036] Dual-input single-output mode DISO-2 working mode: The multiplexed port V DC Connect to the DC power supply, the unidirectional input port V P and the multiplexed port V DC The connected DC power supply inputs power to the converter, which is the energy storage input and output port V B powered by.

[0037] Optionally, in one embodiment of the present invention, the first diode D1 and the fifth switch S5 are swapped, the anode of the first diode D1 is connected to the source of the fifth switch S5, and the drain of the fifth switch S5 is connected to the unidirectional input port V P The cathode of the first diode D1 is connected to the second end of the first inductor L1.

[0038] Optionally, in one embodiment of the present invention, the second diode D2 and the sixth switch S6 are swapped, the anode of the second diode D2 is connected to the source of the sixth switch S6, and the drain of the sixth switch S6 is connected to the unidirectional input port V P The cathode of the second diode D2 is connected to the first end of the second inductor L2.

[0039] Optionally, in one embodiment of the present invention, the first switch S1 and the second switch S2 are swapped, the source of the first switch S1 is connected to the source of the second switch S2, the drain of the first switch S1 is connected to the first end of the first inductor L1, and the drain of the second switch S2 is connected to the energy storage input and output port V B The positive pole is connected.

[0040] Optionally, in one embodiment of the present invention, the third switch S3 and the fourth switch S4 are swapped, the source of the third switch S3 is connected to the source of the fourth switch S4, the drain of the fourth switch S4 is connected to the second end of the first inductor L1, and the drain of the third switch S3 is connected to the multiplexing port V DC The positive pole is connected.

[0041] The multi-directional high step-down / step-down ratio three-port non-isolated DC converter with port multiplexing of the present invention has the following beneficial effects:

[0042] 1. Port multiplexing and multi-directional power flow: The new converter topology of the present invention innovatively designs a multiplexing port VDC, which can be connected to the load to consume energy and to the DC power supply to input energy to the converter. The multiplexing port not only improves the flexibility of the system, but also realizes the bidirectional flow of power between multiple ports. When the photovoltaic power generation power is insufficient or even without light, the multiplexing port can charge the energy storage module, avoiding over-discharge of the energy storage module, solving the charging problem of the energy storage module within the topology, reducing dependence on external charging devices, and significantly improving the energy management efficiency of the system.

[0043] 2. Wide gain characteristics and strong adaptability with multi-directional high buck-boost ratio: The converter has a wide gain characteristic with high buck-boost ratio between two ports. It can realize boost or buck function in various working modes, and its gain range is wider than that of traditional three-port non-isolated DC converter. The wide gain characteristic not only enables the converter to adapt to a wider range of input voltage changes, but also meets the needs of loads, energy storage modules and photovoltaic systems of different voltage levels, greatly enhancing the adaptability and flexibility of the system.

[0044] 3. Support multiple working modes: The present invention supports seven different working modes, including four single-input single-output (SISO) modes, one single-input dual-output (SIDO) mode, and two dual-input single-output (DISO) modes, and can flexibly adjust the working mode according to different application requirements. This diversity of modes enables the converter to work efficiently under different working conditions and provide support for more application scenarios, including insufficient light or long-term no light scenarios, to ensure stable and reliable operation of the system.

[0045] 4. Simplify system design and reduce costs: Through the design of port multiplexing and multi-directional power flow, the present invention effectively reduces the number of independent converters and switches in the system, reduces circuit complexity and system scale, and thus reduces volume and cost. This compact advantage is particularly suitable for the application of large-scale photovoltaic storage systems, which can significantly improve the overall cost performance.

[0046] 5. Efficient energy conversion: The converter can achieve efficient energy conversion between photovoltaic, energy storage module and load, and can always maintain high-efficiency working state under different input power conditions to ensure the reliability and stability of the system. Especially when the photovoltaic power generation fluctuates greatly, the converter can intelligently adjust the power flow according to the state of the energy storage module, optimize energy use, and ensure the continuous and efficient operation of the system.

[0047] In summary, the three-port non-isolated DC converter of the present invention not only improves the performance and flexibility of the system, but also greatly reduces the complexity and cost of the system by virtue of its innovative port multiplexing design, multi-directional wide gain characteristics, multi-mode working capability and strong adaptability, thus meeting the growing and diversified needs of photovoltaic storage systems and having broad application prospects.

[0048] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0050] Figure 1 A schematic diagram of a multi-directional high step-down / step-down ratio three-port non-isolated DC converter with port multiplexing provided by an embodiment of the present invention;

[0051] Figure 2 A working mode diagram of a multi-directional high step-down / step-down ratio three-port non-isolated DC converter with port multiplexing provided by an embodiment of the present invention;

[0052] Figure 3 Port voltage waveforms of a three-port non-isolated DC converter with multi-directional high step-down / step-down ratio and port multiplexing in different working modes provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0054] When the photovoltaic power generation is insufficient or the photovoltaic power generation is not working, the converter of the present invention can charge the energy storage module connected to the energy storage input and output port through the multiplexing port, which can not only prevent the energy storage module from over-discharging, but also provide more reserve energy for the system, avoid adding additional energy storage charging devices, and thus improve the energy management efficiency of the system.

[0055] At the same time, the converter has a wide gain characteristic of multi-directional high buck-boost ratio, strong adaptability, and can maintain a stable output voltage when the input voltage fluctuates greatly, and adapt to loads, energy storage modules, DC power supplies and photovoltaic systems of different voltage levels. Its wide gain characteristic and high adaptability enable the converter to operate efficiently under complex working conditions, ensure the reliability and stability of the system, and meet the needs of various application scenarios. The following is a detailed introduction to the multi-directional high buck-boost ratio three-port non-isolated DC converter with port multiplexing of the embodiment of the present invention through embodiments and drawings.

[0056] Figure 1 A schematic diagram of a three-port non-isolated DC converter with high step-down / step-down ratio and multiple ports provided in an embodiment of the present invention.

[0057] like Figure 1 As shown, the multi-directional high step-down ratio three-port non-isolated DC converter with port multiplexing includes: a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first diode D1, a second diode D2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a unidirectional input port V P , Energy storage input and output port V B and multiplexed port V DC .

[0058] Specifically, the unidirectional input port V P Connecting to a photovoltaic power generation port for converting light energy into electrical energy and providing input energy to a converter;

[0059] Energy storage input and output port V B Connecting an energy storage system to input or output energy to the converter;

[0060] Multiplex port V DC Connecting a load or a DC power source to consume energy or provide energy input for the converter;

[0061] Unidirectional input port V P The positive electrode is connected to the anode of the first diode D1 and the anode of the second diode D2, and the unidirectional input port V P The negative pole is grounded and connected to the energy storage input and output port V B The negative electrode of the first capacitor C1, the source of the seventh switch S7, and the second end of the second inductor L2 are connected;

[0062] Energy storage input and output port V B The positive electrode is connected to the first end of the first capacitor C1 and the source of the first switch S1, and the energy storage input and output port V B The negative electrode is grounded and connected to the second end of the first capacitor C1, the source of the seventh switch S7, and the second end of the second inductor L2;

[0063] Multiplex port V DC The positive electrode is connected to the first end of the second capacitor C2 and the source of the fourth switch S4, and the multiplexing port V DC The negative electrode is connected to the second end of the second capacitor C2, the first end of the second inductor L2, the source of the sixth switch S4, and the source of the eighth switch S8;

[0064] The drain of the first switch S1 is connected to the drain of the second switch S2, and the source of the first switch S1 is connected to the first end of the first capacitor C1;

[0065] The source of the second switch S2 is connected to the first end of the first inductor L1 and the drain of the eighth switch S8;

[0066] The drain of the third switch S3 is connected to the drain of the fourth switch S4, and the source of the third switch S3 is connected to the second end of the first inductor L1, the source of the fifth switch S5, and the drain of the seventh switch S7;

[0067] A source of the fourth switch S4 is connected to a first end of the second capacitor C2;

[0068] The drain of the fifth switch S5 is connected to the cathode of the first diode D1, and the source of the fifth switch S5 is connected to the second end of the first inductor L1 and the drain of the seventh switch S7;

[0069] The drain of the sixth switch S6 is connected to the cathode of the second diode D2, and the source of the sixth switch S6 is connected to the source of the eighth switch S8, the first end of the second inductor L2, and the second end of the second capacitor C2;

[0070] The drain of the seventh switch S7 is grounded and connected to the second end of the first inductor L1, and the source of the seventh switch S7 is connected to the second end of the second capacitor C2 and the second end of the second inductor L2;

[0071] The drain of the eighth switch S8 is connected to the first end of the first inductor L1, and the source of the eighth switch S8 is connected to the first end of the second inductor L2 and the second end of the second capacitor C2;

[0072] The anode of the first diode D1 is connected to the anode of the second diode D2;

[0073] A second end of the first capacitor C1 is grounded and connected to a second end of the second inductor L2;

[0074] The second end of the second capacitor C2 is connected to the first end of the second inductor L2.

[0075] In one embodiment, the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7, and the eighth switch S8 all use NMOS tubes. Alternatively, the first switch S1, the second switch S2, the third switch S3, the fourth switch S4, the fifth switch S5, the sixth switch S6, the seventh switch S7, and the eighth switch S8 may all use PMOS tubes, or NPN transistors or IGBT tubes with diodes connected in reverse parallel.

[0076] In the embodiment of the present invention, the cathode of the first diode D1 is connected to the drain of the fifth switch S5, and the first diode D1 and the fifth switch S5 control the unidirectional flow of power at the unidirectional input port. In one embodiment, alternatively, the combination of the first diode D1 and the fifth switch S5 can also use other types of unidirectional switches, or the first diode D1 and the fifth switch S5 are swapped, the anode of the first diode D1 is connected to the source of the fifth switch tube S5, and the drain of the fifth switch tube S5 is connected to the unidirectional input port V P The cathode of the first diode D1 is connected to the second end of the first inductor L1.

[0077] In the embodiment of the present invention, the cathode of the second diode D2 is connected to the drain of the sixth switch S6, and the second diode D2 and the sixth switch S6 control the unidirectional input port V P Power flows in one direction. In one embodiment, alternatively, the combination of the second diode D2 and the sixth switch S6 may also adopt other types of unidirectional switches, or the second diode D2 and the sixth switch S6 may be swapped, the anode of the second diode D2 is connected to the source of the sixth switch tube S6, and the drain of the sixth switch tube S6 is connected to the unidirectional input port V P The cathode of the second diode D2 is connected to the first end of the second inductor L2.

[0078] In the embodiment of the present invention, the drain of the first switch S1 is connected to the drain of the second switch S2, and the first switch S1 and the second switch S2 control the energy storage input and output port power V BBidirectional flow. In one embodiment, alternatively, the combination of the first switch S1 and the second switch S2 may also adopt other types of bidirectional switches, or the first switch S1 and the second switch S2 may be swapped, the source of the first switch S1 is connected to the source of the second switch tube S2, the drain of the first switch tube S1 is connected to the first end of the first inductor L1, and the drain of the second switch tube S2 is connected to the energy storage input and output port V B The positive pole is connected.

[0079] In the embodiment of the present invention, the drain of the third switch S3 is connected to the drain of the fourth switch S4, and the third switch S3 and the fourth switch S4 control the multiplexing port power V DC In one embodiment, alternatively, the combination of the third switch S3 and the fourth switch S4 may also adopt other types of bidirectional switches, or the third switch S3 and the fourth switch S4 may be swapped, the source of the third switch S3 is connected to the source of the fourth switch S4, the drain of the fourth switch S4 is connected to the second end of the first inductor L1, and the drain of the third switch S3 is connected to the multiplexing port V DC The positive pole is connected.

[0080] In an embodiment of the present invention, Figure 2 As shown, the three-port non-isolated DC converter is used to realize seven operating modes, including: four single-input single-output operating modes (SISO), one single-input dual-output operating mode (SIDO) and two dual-input single-output (DISO) operating modes.

[0081] The seven operating modes of the three-port non-isolated DC converter are:

[0082] Single-input single-output mode SISO-1: Multiplexing port V DC Connect to the load, unidirectional input port V P No power is input to the system, energy storage input and output port V B Input power to supply power to the load. In addition, this mode can achieve buck-boost and buck-boost gain, and the buck-boost gain is wider than the traditional buck-boost converter, see Figure 3 (a). This mode is suitable for situations where the photovoltaic power generation system is not working, especially at night when there is no light. The energy storage system provides stable power to the load without relying on direct output from the photovoltaic power source, thus solving the problem of volatility in photovoltaic power generation.

[0083] Single-input single-output mode SISO-2: The unidirectional input port does not input power to the system, and the multiplexed port V DC Connect to the DC power supply, input power to the converter, and provide energy storage input and output ports V B In addition, this mode can realize buck-boost and buck-boost, and the buck-boost gain is wider than that of the traditional buck-boost converter, see Figure 3(b). This mode is suitable for situations where the photovoltaic power generation system and the load are not working. For example, when there is no light at night, the photovoltaic power generation cannot work. At the same time, the electricity price is cheap at night. The external DC power supply is used to charge the energy storage system to ensure that the energy storage system can input energy to the system when it is needed.

[0084] Single-input single-output mode SISO-3: Energy storage input and output port V B Does not participate in converter energy exchange, reuses port V DC Connect to the load, unidirectional input port V P Input power to supply power to the load. In addition, this mode can realize buck-boost and buck-boost, and the buck-boost gain is wider than that of the traditional buck-boost converter, see Figure 3 (c). It is suitable for daytime environments, especially when photovoltaic power generation is relatively stable and does not require energy storage intervention, and photovoltaic power is directly used to supply power to the load.

[0085] Single-input single-output mode SISO-4: Multiplexing port V DC Does not participate in the converter energy exchange, unidirectional input port V P Input power, for energy storage input and output ports V B Power supply. See Figure 3 (d). This mode is suitable for the photovoltaic power generation system to input electric energy into the energy storage system through the unidirectional input port. When the light conditions are good and the load does not need to work, the photovoltaic power generation energy is stored for later use.

[0086] Single-input dual-output mode SIDO: multiplexed port V DC Connect to the load, unidirectional input port V P Input power, and also energy storage input and output ports V B and multiplexed port V DC In addition, this mode can realize buck-boost and buck-boost, and the buck-boost gain is wider than that of the traditional buck-boost converter, see Figure 3 (e). It is suitable for scenarios where photovoltaic power generation supplies power to both the energy storage system and the load, ensuring that the load is powered while also storing the energy for subsequent needs.

[0087] Dual-input single-output mode DISO-1: Multiplex port V DC Connect to the load, unidirectional input port V P and energy storage input and output ports V B The power is input to the converter together to supply power to the load. In addition, this mode can achieve buck-boost and buck-boost gain, and the buck-boost gain is wider than that of the traditional buck-boost converter. Figure 3(f). This mode is applicable to scenarios where photovoltaic power generation and energy storage systems jointly provide power to the load. It is applicable to situations where photovoltaic power generation is insufficient, and the energy storage system and photovoltaic power source work together to ensure that the power demand of the load is met.

[0088] Dual-input single-output mode DISO-2 working mode: multiplexed port V DC Connect to DC power supply, unidirectional input port V P and multiplexed port V DC The connected DC power supply inputs power to the converter, which is the energy storage input and output port V B In addition, this mode can realize buck-boost and buck-boost, and the buck-boost gain is wider than that of the traditional buck-boost converter, see Figure 3 (g). This mode is suitable for scenarios where the load does not need to work and the energy storage needs to be charged as quickly as possible. When photovoltaic power generation cannot meet the charging needs of the energy storage system, an external DC power supply charges the energy storage system for subsequent needs.

[0089] In an embodiment of the present invention, the converter is a three-port non-isolated DC converter, which innovatively replaces the traditional load port with a multiplexed port V DC , which is equivalent to increasing the number of ports of the converter, and combined with the characteristics of the converter's multiplexed port power flow in both directions, seven modes of operation can be achieved, of which three ports can be used as input ports, and the energy storage input and output port V B and multiplexed port V DC It can also be used as an output port. Port multiplexing and multi-directional power flow enable the converter to be applied to more application scenarios, including those without sunlight for a long time.

[0090] The converter has a wide gain characteristic with a multi-directional high buck-boost ratio. In various working modes, the converter can achieve the function of boosting or bucking, and its gain range is wider than that of traditional three-port non-isolated converters with the same number of components. The wide gain characteristic enables the converter to adapt to a wider range of voltage levels, reduce the restrictions on port voltage, support loads, DC power supplies, energy storage modules and photovoltaic systems of different voltage levels, and further enhance the flexibility and adaptability of the system.

[0091] The present invention provides a three-port non-isolated DC converter with high buck-boost ratio and multiplexed ports, which is innovative and practical. By introducing multiplexed ports and bidirectional power flow characteristics, energy management is optimized, and the adaptability and flexibility of the system are improved; its wide gain characteristics can adapt to a wider range of voltage changes, ensure output voltage stability, and meet the needs of loads of different voltage levels and photovoltaic storage systems; at the same time, the converter supports multiple working modes, enabling it to operate efficiently in different application scenarios, especially in the case of insufficient photovoltaic power generation, it can effectively protect the energy storage module and improve the reliability of the system.

[0092] In addition, the present invention not only reduces system complexity, but also effectively reduces cost and volume by simplifying circuit design and reducing the use of independent converters, further improving the overall cost performance. Therefore, the three-port non-isolated DC converter has a wide range of application prospects, especially suitable for photovoltaic storage systems, and can solve the problems of limited gain range, single working mode and high system complexity in the prior art, providing strong technical support for efficient energy exchange and optimized management of photovoltaic storage systems.

[0093] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0094] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

Claims

1. A three-port non-isolated DC converter with high step-down / step-down ratio and multiple ports, characterized in that: include: A first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a fifth switch S5, a sixth switch S6, a seventh switch S7, an eighth switch S8, a first diode D1, a second diode D2, a first inductor L1, a second inductor L2, a first capacitor C1, a second capacitor C2, a unidirectional input port V P , Energy storage input and output port V B and multiplexed port V DC ; The unidirectional input port V P Connecting to a photovoltaic power generation port for converting light energy into electrical energy and providing input energy to a converter; The energy storage input and output port V B Connecting an energy storage system to input or output energy to the converter; The multiplexing port V DC Connecting a load or a DC power source to consume energy or provide energy input for the converter; The unidirectional input port V P The positive electrode is connected to the anode of the first diode D1 and the anode of the second diode D2, and the unidirectional input port V P The negative pole is grounded and connected to the energy storage input output port V B The negative electrode of the first capacitor C1, the source of the seventh switch S7, and the second end of the second inductor L2 are connected; The energy storage input and output port V B The positive electrode is connected to the first end of the first capacitor C1 and the source of the first switch S1, and the energy storage input and output port V B The negative electrode is grounded and connected to the second end of the first capacitor C1, the source of the seventh switch S7, and the second end of the second inductor L2; The multiplexing port V DC The positive electrode is connected to the first end of the second capacitor C2 and the source of the fourth switch S4, and the multiplexing port V DC The negative electrode is connected to the second end of the second capacitor C2, the first end of the second inductor L2, the source of the sixth switch S4, and the source of the eighth switch S8; The drain of the first switch S1 is connected to the drain of the second switch S2, and the source of the first switch S1 is connected to the first end of the first capacitor C1; The source of the second switch S2 is connected to the first end of the first inductor L1 and the drain of the eighth switch S8; The drain of the third switch S3 is connected to the drain of the fourth switch S4, and the source of the third switch S3 is connected to the second end of the first inductor L1, the source of the fifth switch S5, and the drain of the seventh switch S7; The source of the fourth switch S4 is connected to the first end of the second capacitor C2; The drain of the fifth switch S5 is connected to the cathode of the first diode D1, and the source of the fifth switch S5 is connected to the second end of the first inductor L1 and the drain of the seventh switch S7; The drain of the sixth switch S6 is connected to the cathode of the second diode D2, and the source of the sixth switch S6 is connected to the source of the eighth switch S8, the first end of the second inductor L2, and the second end of the second capacitor C2; The drain of the seventh switch S7 is grounded and connected to the second end of the first inductor L1, and the source of the seventh switch S7 is connected to the second end of the second capacitor C2 and the second end of the second inductor L2; The drain of the eighth switch S8 is connected to the first end of the first inductor L1, and the source of the eighth switch S8 is connected to the first end of the second inductor L2 and the second end of the second capacitor C2; The anode of the first diode D1 is connected to the anode of the second diode D2; The second end of the first capacitor C1 is grounded and connected to the second end of the second inductor L2; The second end of the second capacitor C2 is connected to the first end of the second inductor L2.

2. The three-port non-isolated DC converter according to claim 1, characterized in that: The three-port non-isolated DC converter is used to realize seven working modes, including: four single-input single-output working modes, one single-input dual-output working mode and two dual-input single-output working modes.

3. The three-port non-isolated DC converter according to claim 2, characterized in that: The seven operating modes of the three-port non-isolated DC converter are: Single-input single-output mode SISO-1: The multiplexed port V DC Connect the load, the unidirectional input port V P No power is input to the system, the energy storage input output port V B Input power, supplying power to the load; Single-input single-output mode SISO-2: The unidirectional input port does not input power to the system, and the multiplexed port V DC Connect to the DC power supply, input power to the converter, and provide the energy storage input and output port V B powered by; Single-input single-output mode SISO-3: The energy storage input and output port V B does not participate in the converter energy exchange, the multiplexing port V DC Connect the load, the unidirectional input port V P Input power, supplying power to the load; Single-input single-output mode SISO-4: The multiplexed port V DC The unidirectional input port V P Input power, for the energy storage input and output ports V B powered by; Single-input dual-output mode SIDO: The multiplexed port V DC Connect the load, the unidirectional input port V P Input power, while the energy storage input and output ports V B and the multiplexed port V DC Power supply for connected loads; Dual-input single-output mode DISO-1: The multiplexed port V DC Connect the load, the unidirectional input port V P and the energy storage input and output ports V B Commonly input power to the converter to supply power to the load; Dual-input single-output mode DISO-2 working mode: The multiplexed port V DC Connect to the DC power supply, the unidirectional input port V P and the multiplexed port V DC The connected DC power supply inputs power to the converter, which is the energy storage input and output port V B powered by.

4. The three-port non-isolated DC converter according to claim 1, characterized in that: The first diode D1 and the fifth switch S5 are exchanged, the anode of the first diode D1 is connected to the source of the fifth switch S5, and the drain of the fifth switch S5 is connected to the unidirectional input port V P The cathode of the first diode D1 is connected to the second end of the first inductor L1.

5. The three-port non-isolated DC converter according to claim 1, characterized in that: The second diode D2 and the sixth switch S6 are exchanged, the anode of the second diode D2 is connected to the source of the sixth switch S6, and the drain of the sixth switch S6 is connected to the unidirectional input port V P The cathode of the second diode D2 is connected to the first end of the second inductor L2.

6. The three-port non-isolated DC converter according to claim 1, characterized in that: The first switch S1 and the second switch S2 are swapped, the source of the first switch S1 is connected to the source of the second switch S2, the drain of the first switch S1 is connected to the first end of the first inductor L1, and the drain of the second switch S2 is connected to the energy storage input and output port V B The positive pole is connected.

7. The three-port non-isolated DC converter according to claim 1, characterized in that: The third switch S3 and the fourth switch S4 are swapped, the source of the third switch S3 is connected to the source of the fourth switch S4, the drain of the fourth switch S4 is connected to the second end of the first inductor L1, and the drain of the third switch S3 is connected to the multiplexing port V DC The positive pole is connected.

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