Multidirectional high buck-boost ratio three-port non-isolated DC / DC converter with port multiplexing

Abstract

The present invention discloses a multi-directional high buck-boost ratio three-port non-isolated DC converter with port multiplexing, which belongs to the field of power electronics. The traditional load port is replaced by a multiplexing port, which increases the number of ports of the converter. When the photovoltaic power generation power is insufficient or the photovoltaic power generation is not working, the energy storage module connected to the energy storage input and output port can be charged through the multiplexing port, which not only prevents the energy storage module from over-discharging, but also provides more reserve energy for the system, avoids the addition of additional energy storage charging devices, and thus improves the energy management efficiency of the system. At the same time, the converter has a wide gain characteristic of multi-directional high buck-boost ratio and strong adaptability. It can keep the output voltage stable when the input voltage fluctuates greatly, and can adapt to loads, energy storage modules, DC power supplies and photovoltaic systems of different voltage levels. It can operate efficiently under complex working conditions, ensure the reliability and stability of the system, and meet the needs of various application scenarios.

Description

Technical Field

[0001] The present 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 DC 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 address the volatility of renewable energy, the rapid development of energy storage technology, particularly electrochemical energy storage, has provided crucial support. The integrated application of photovoltaic and energy storage systems (PV-storage systems) plays a crucial role in improving energy efficiency and enhancing power system stability. As a core component in PV-storage systems, three-port DC converters enable efficient energy exchange between photovoltaics, energy storage, and loads, providing a viable solution for addressing power transmission and voltage stability issues in distributed energy systems.

[0004] Three-port DC / DC converters are primarily categorized into three-port isolated DC / DC converters and three-port non-isolated DC / DC converters. Three-port non-isolated DC / DC converters are widely used due to their simpler topology, higher power density, and higher conversion efficiency. However, existing three-port non-isolated DC / DC converters suffer from the following major issues.

[0005] First, most 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 existing three-port non-isolated DC converters 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, under long-term low light or no light conditions, users need to charge the energy storage module in advance, but the load port of the existing three-port non-isolated DC converter topology structure cannot achieve reverse energy transmission, resulting in it being unable to charge the energy storage module inside the topology or achieve fast charging when the light is insufficient, and an additional charging device must be equipped. Therefore, how to achieve more power transmission modes from the topology structure without the need for additional charging devices is the problem that the present invention focuses on solving.

[0006] Secondly, although three-port non-isolated DC converters have higher power density and higher conversion efficiency than isolated converters, current three-port non-isolated DC converters still face bottlenecks in achieving a wide transformation ratio and cannot meet the wide transformation ratio requirements of certain photovoltaic storage systems. For example, in order to achieve wide gain, existing three-port non-isolated DC converters use 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 places high demands on the production process. In addition, most existing three-port non-isolated DC converters can only operate 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 with a 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, traditional three-port non-isolated DC / DC converters typically achieve multiple inputs through switches or the series or parallel connection of multiple independent converters. This not only increases circuit complexity but also increases the number of system components and costs. Another key issue addressed by the present invention is how to reduce the number of switching components in a three-port non-isolated DC / DC converter while simultaneously achieving port multiplexing and a high multi-directional buck-boost ratio.

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

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

[0010] The embodiment of the present invention provides a multi-directional high step-up / 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 to the energy storage system to input or output energy to the converter;

[0013] The multiplexing port V DC Connect to a load or DC power supply 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 second end 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 and output ports 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 Does not participate in the converter energy exchange, 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, and at the same time 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 port 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 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-up / 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 novel converter topology of the present invention innovatively designs a multiplexing port VDC, which can be connected to both the load to consume energy and the DC power supply to input energy to the converter. The multiplexing port not only improves the flexibility of the system, but also enables bidirectional power flow between multiple ports. When the photovoltaic power generation power is insufficient or even without sunlight, the multiplexing port can charge the energy storage module, avoiding over-discharge of the energy storage module. This solves the charging problem of the energy storage module within the topology, reduces dependence on external charging devices, and significantly improves the energy management efficiency of the system.

[0043] 2. Wide Gain Characteristics and Strong Adaptability with Multi-Directional High Buck-Boost Ratios: This converter features a wide gain characteristic with high buck-boost ratios between ports, enabling both step-up and step-down functions in various operating modes. Compared to traditional three-port non-isolated DC / DC converters, its gain range is wider. This wide gain characteristic not only enables the converter to adapt to a wider range of input voltage variations, but also meets the requirements of loads, energy storage modules, and photovoltaic systems with different voltage levels, greatly enhancing the system's adaptability and flexibility.

[0044] 3. Support for Multiple Operating Modes: This invention supports seven different operating modes, including four single-input single-output (SISO) modes, one single-input dual-output (SIDO) mode, and two dual-input single-output (DISO) modes, allowing flexible adjustment of operating modes based on different application requirements. This diverse mode enables the converter to operate efficiently under different operating conditions, providing support for more application scenarios, including low-light conditions or prolonged periods of no light, ensuring stable and reliable system operation.

[0045] 4. Simplified system design and cost reduction: By utilizing port multiplexing and multi-directional power flow, this invention effectively reduces the number of independent converters and switches in the system, reducing circuit complexity and system scale, thereby reducing size and cost. This compactness is particularly suitable for large-scale solar storage systems, significantly improving overall cost-effectiveness.

[0046] 5. Efficient Energy Conversion: This converter enables efficient energy conversion between photovoltaics, energy storage modules, and loads. It consistently maintains high efficiency under varying input power conditions, ensuring system reliability and stability. Especially when photovoltaic power generation fluctuates significantly, the converter intelligently adjusts power flow based on the state of the energy storage module, optimizing energy usage and ensuring continued efficient system operation.

[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 diversified needs of photovoltaic storage systems and having broad application prospects.

[0048] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may 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 readily 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-up / step-down ratio three-port non-isolated DC converter with port multiplexing provided by an embodiment of the present invention;

[0051] Figure 2 An operating 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 operating modes provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The following describes embodiments of the present invention in detail, 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 are not to be construed as limiting the present invention.

[0054] When the photovoltaic power generation power 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 not only prevents the energy storage module from over-discharging, but also provides more reserve energy for the system, avoids the need to add additional energy storage charging devices, and thus improves the energy management efficiency of the system.

[0055] At the same time, the converter has a wide gain characteristic with multi-directional high buck-boost ratio and strong adaptability. It can maintain a stable output voltage when the input voltage fluctuates greatly, and can 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, ensuring the reliability and stability of the system and meeting the needs of various application scenarios. The following is a detailed description of the multi-directional high buck-boost ratio three-port non-isolated DC converter with port multiplexing according to the embodiment of the present invention through examples and drawings.

[0056] Figure 1 A schematic diagram of a three-port non-isolated DC converter with high step-up / down ratio and port multiplexing provided by 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 to the energy storage system to input or output energy to the converter;

[0060] Multiplex port V DC Connect to a load or DC power supply 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 second end 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 the 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 are all NMOS transistors. 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 be PMOS transistors, or NPN transistors or IGBTs with diodes connected in reverse parallel.

[0076] In an 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 can be swapped, with the anode of the first diode D1 connected to the source of the fifth switch tube S5, and the drain of the fifth switch tube S5 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 be another type of unidirectional switch, or the second diode D2 and the sixth switch S6 may be swapped, with the anode of the second diode D2 connected to the source of the sixth switch S6, and the drain of the sixth switch S6 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 be another type of bidirectional switch, or the third switch S3 and the fourth switch S4 may be swapped, with the source of the third switch S3 connected to the source of the fourth switch S4, the drain of the fourth switch S4 connected to the second end of the first inductor L1, and the drain of the third switch S3 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: Multiplex port V DC Connect to the load, unidirectional input port V P No power is input to the system, energy storage input and output ports V B Input power to supply power to the load. In addition, this mode can realize buck-boost and buck-boost gain, and the buck-boost gain is wider than that of 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 photovoltaic power generation volatility.

[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 the energy storage input and output port V B In addition, this mode can realize buck-boost and buck-boost gain, and the buck-boost gain is wider than that of 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, at night when there is no sunlight, the photovoltaic power generation cannot work. At the same time, the electricity price is cheaper 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 gain wider than the traditional buck-boost converter, see Figure 3 (c) This is suitable for daytime environments, especially when photovoltaic power generation is relatively stable and does not require energy storage intervention, and the photovoltaic power source is directly used to supply power to the load.

[0085] Single-input single-output mode SISO-4: Multiplex port V DC Does not participate in the converter energy exchange, unidirectional input port V P Input power, for energy storage input and output port V B Power supply. See Figure 3 (d) This mode is suitable for photovoltaic power generation systems that input electrical energy into the energy storage system through a 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 the energy storage input and output ports V B and multiplexed port V DC In addition, this mode can realize buck-boost and buck-boost gain, and the buck-boost gain is wider than that of traditional buck-boost converter, see Figure 3 (e) This is suitable for scenarios where photovoltaic power generation simultaneously supplies power to the energy storage system and the load, ensuring that the load is powered while also storing the energy for subsequent use.

[0087] Dual-input single-output mode DISO-1: multiplexed 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 suitable for scenarios where photovoltaic power generation and energy storage systems jointly provide power to the load. It is also suitable for scenarios where photovoltaic power generation is insufficient, where 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: multiplex 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 gain, and the buck-boost gain is wider than that of 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 the 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 multiplexing port power can flow in both directions, it can realize seven modes of operation, 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 serve as an output port. Port multiplexing and multi-directional power flow enable the converter to be applied in more application scenarios, including those without sunlight for a long time.

[0090] This converter features a wide gain characteristic with a multi-directional high step-up and step-down ratio. It can perform both step-up and step-down functions in various operating modes, and its gain range is wider than that of a traditional three-port non-isolated converter with the same number of components. This wide gain characteristic enables the converter to adapt to a wider range of voltage levels, reducing port voltage restrictions and supporting loads, DC power supplies, energy storage modules, and photovoltaic systems of varying voltage levels, further enhancing system flexibility and adaptability.

[0091] This invention provides a multi-directional, high-step-down / step-down ratio, three-port, non-isolated DC converter with port multiplexing, demonstrating significant innovation and practicality. By introducing multiplexed ports and bidirectional power flow, it optimizes energy management and enhances the system's adaptability and flexibility. Its wide gain characteristic adapts to a wider range of voltage variations, ensuring stable output voltage and meeting the needs of loads with varying voltage levels and photovoltaic storage systems. Furthermore, the converter supports multiple operating modes, enabling efficient operation in diverse application scenarios. This capability effectively protects the energy storage module and improves system reliability, particularly in situations where photovoltaic power generation is insufficient.

[0092] Furthermore, by simplifying circuit design and eliminating the need for independent converters, this invention not only reduces system complexity but also effectively reduces cost and size, further improving overall cost-effectiveness. Therefore, this three-port non-isolated DC converter has broad application prospects, particularly in photovoltaic storage systems. It can address existing issues such as limited gain range, single operating mode, and high system complexity, providing strong technical support for efficient energy exchange and optimized management in 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" 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 can be combined in any one or N embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

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

Claims

1. A three-port non-isolated DC converter with high step-up / down ratio and multiplexing port capability, characterized in that: include: First switch S1, second switch S2, third switch S3, fourth switch S4, fifth switch S5, sixth switch S6, seventh switch S7, eighth switch S8, first diode D1, second diode D2, first inductor L1, second inductor L2, first capacitor C1, second capacitor C2, 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 to the energy storage system to input or output energy to the converter; The multiplexing port V DC Connect to a load or DC power supply 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 second end 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 S6, 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 source of the seventh switch S7 is grounded, and the drain of the seventh switch S7 is connected to the second end of the first inductor L1; 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 and output ports 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 Does not participate in the converter energy exchange, 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, and at the same time 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 port 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 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 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.

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 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.

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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