A wide input non-isolated three-port converter for photovoltaic systems

Abstract

A wide input non-isolated three-port converter suitable for a photovoltaic system, characterized in that it comprises a four-switch buck-boost conversion unit (1), a pulse voltage unit (2) and a battery charging branch unit (3), wherein the switch buck-boost conversion unit (1) is connected in parallel with the pulse voltage unit (2), and the pulse voltage unit (2) is connected with the battery charging branch unit (3), and mainly comprises a photovoltaic input power supply, seven switch tubes, four diodes, an inductor L, an output filter capacitor C and a resistive load. The converter contains only one inductor, which reduces the topological volume and solves the problem of large volume of the existing converter. At the same time, the proposed control strategy can realize energy transfer between the three ports, making the energy flow between the ports easy to manage. At the same time, the topology widens the input voltage range, can complete the management of system modes and smooth switching between systems, and is convenient for practical design and application.

Description

Technical Field

[0001] The invention relates to the technical field of power electronics, and in particular to a wide-input non-isolated three-port converter suitable for a photovoltaic system. Background Art

[0002] As one of the emerging energy sources, solar energy is of great significance to alleviating energy crisis, environmental pollution and other problems. Since solar energy is affected by light intensity and time, it is unstable and unsustainable. Therefore, it is necessary to introduce energy storage units to balance system power in independent renewable power systems and provide energy to the load side. Traditional renewable energy power supply systems often require multiple independent converters to connect input sources, energy storage batteries and load ends, which makes the system have problems such as large volume and mass, high cost and poor reliability. The three-port converter is an ideal choice for connecting renewable energy, energy storage units and loads in new energy power generation systems. It has the advantages of small size, fewer components and unified energy flow management between ports, which can reduce the volume and mass of the system and reduce system losses.

[0003] However, existing non-isolated three-port converters have many problems, such as narrow converter operating range, strong port voltage constraints, or multi-stage conversion resulting in large converter size, low energy utilization efficiency, and parallel input structure leading to time-sharing power supply.

[0004] Therefore, a wide-input non-isolated three-port converter suitable for photovoltaic systems is designed to solve the above problems. Summary of the invention

[0005] In response to the above technical problems, the present invention provides a wide-input non-isolated three-port converter suitable for photovoltaic systems. This topology can broaden the voltage constraints of the energy storage port and the photovoltaic port. The use of a single inductor structure can reduce the size of the converter. The use of a series structure at the input stage can avoid the shortcomings brought about by the time-sharing strategy and meet the application requirements of a wide range of changes in the photovoltaic port.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A wide input non-isolated three-port converter suitable for a photovoltaic system, characterized in that it includes a four-switch buck-boost conversion unit, a pulse voltage unit, and a battery charging branch unit, wherein the switch buck-boost conversion unit is connected in parallel with the pulse voltage unit, the pulse voltage unit is connected to the battery charging branch unit, the pulse voltage unit is used to generate an access circuit for a battery Vb and form a discharge path for the battery Vb, and the battery charging branch unit is used to generate a charging path for the battery Vb.

[0008] The four-switch buck-boost conversion unit includes a switch tube S1, a switch tube S2, an inductor L, a switch tube S6 and a diode VD2. The drain D of the switch tube S1 is connected to the positive electrode of the photovoltaic input power source Vpv, the source S of the switch tube S1 is connected to the drain D of the switch tube S2, the source S of the switch tube S2 is connected to the negative electrode of the photovoltaic input power source Vpv, one end of the inductor L is connected to the drain D of the switch device S6, the anode A of the diode VD2 is connected to the drain D of the switch device S6, and the cathode K of the diode VD2 is connected to the positive electrode + of the output capacitor C. The above circuit connection is used for the discharge path of the photovoltaic input power source Vpv.

[0009] The pulse voltage unit includes a battery Vb, a switch tube S3, a switch tube S7, a diode VD1, and a diode VD3. The drain D of the switch tube S3 is connected to the anode A of the diode VD1, the source S of the switch tube S3 is connected to the negative electrode - of the battery Vb, the drain D of the switch tube S7 is connected to the cathode K of the diode VD1, the source S of the switch tube S7 is connected to the cathode K of the diode VD3, the anode A of the diode VD1 is connected to the drain D of the switch tube S3, the cathode K of the diode VD1 is connected to the drain D of the switch tube S7, the anode A of the diode VD3 is connected to the positive electrode + of the battery terminal Vb, and the cathode K of the diode VD3 is connected to the source S of the switch tube S7.

[0010] The battery charging branch unit includes a switch tube S5, a diode VD4 and a switch tube S4, the drain D of the switch tube S5 is connected to the anode A of the diode VD2, the source S of the switch tube S5 is connected to the anode A of the diode VD4, the cathode K of the diode VD4 is connected to the positive electrode + of the battery Vb, the drain D of the switch tube S4 is connected to the cathode - of the battery Vb, and the source S of the switch tube S4 is connected to the negative electrode - of the photovoltaic cell Vpv.

[0011] Beneficial effects of the present invention:

[0012] The present invention is mainly composed of a photovoltaic input power supply, seven switch tubes, four diodes, an inductor L, an output filter capacitor C and a resistive load. The converter contains only one inductor, which reduces the topological volume and solves the problem of large volume of existing converters. At the same time, the proposed control strategy can realize energy transfer between the three ports, making the energy flow between the ports easy to manage. At the same time, the topology widens the input voltage range, can complete the management of system modes and smooth switching between systems, and is convenient for practical design and application.

[0013] The present invention is a subway fixed contact network automatic grinding system with a pressure buffer that can adapt to photovoltaic energy storage working conditions, meet wide range input, and realize photovoltaic and energy storage separate output mode, as well as photovoltaic and energy storage parallel output mode, thereby improving the working environment of workers. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A circuit diagram of a wide-input non-isolated three-port converter suitable for a photovoltaic system according to the present invention;

[0015] Figure 2 It is a schematic diagram of the four modes of the present invention;

[0016] As shown in the figure: 1. Four-switch buck-boost conversion unit, 2. Pulse voltage unit, 3. Battery charging branch unit, photovoltaic input power supply Vpv, switch tube S1, switch tube S2, switch tube S3, switch tube S4, switch tube S5, switch tube S6, switch tube S7, inductor L, diode VD1, diode VD2, diode VD3, diode VD4, battery Vb. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0019] Example 1

[0020] like Figure 1 As shown, the present invention provides a wide input non-isolated three-port converter suitable for a photovoltaic system, characterized in that it comprises a four-switch buck-boost conversion unit (1), a pulse voltage unit (2) for generating a connection circuit for a battery Vb and forming a discharge path for the battery Vb; and a battery charging branch unit (3) for generating a charging path for the battery Vb.

[0021] like Figure 1 As shown, the four-switch buck-boost conversion unit (1) also includes a switch tube S1, a switch tube S2, an inductor L, a switch tube S6 and a diode VD2; the drain electrode D of the switch tube S1 is connected to the positive electrode of the photovoltaic input power source Vpv, the source electrode S of the switch tube S1 is connected to the drain electrode D of the switch tube S2; the source electrode S of the switch tube S2 is connected to the negative electrode of the photovoltaic input power source Vpv; one end of the inductor L is connected to the drain electrode D of the switch device S6; the anode electrode A of the diode VD2 is connected to the drain electrode D of the switch device S6, and the cathode electrode K of the diode VD2 is connected to the positive electrode + of the output capacitor C. The above circuit connection is used for the discharge path of the photovoltaic input power source Vpv.

[0022] like Figure 1 As shown, the pulse voltage unit (2) also includes a battery Vb, a switch tube S3, a switch tube S7, a diode VD1, and a diode VD3; the drain D of the switch tube S3 is connected to the anode A of the diode VD1; the source S of the switch tube S3 is connected to the negative electrode - of the battery Vb; the drain D of the switch tube S7 is connected to the cathode K of the diode VD1; the source S of the switch tube S7 is connected to the cathode K of the diode VD3; the anode A of the diode VD1 is connected to the drain D of the switch tube S3, and the cathode K of the diode VD1 is connected to the drain D of the switch tube S7; the anode A of the diode VD3 is connected to the positive electrode + of the battery terminal Vb, and the cathode K of the diode VD3 is connected to the source S of the switch tube S7; the above connection method forms a pulse voltage unit (2) for a discharge circuit of the battery Vb, and the pulse voltage unit (2) is connected in parallel with the four-switch buck-boost conversion unit (1).

[0023] like Figure 1 As shown, the battery charging branch unit (3) also includes a switch tube S5, a diode VD4, and a switch tube S4. The drain D of the switch tube S5 is connected to the anode A of the diode VD2, and the source S of the switch tube S5 is connected to the anode A of the diode VD4; the cathode K of the diode VD4 is connected to the positive electrode + of the battery Vb; the drain D of the switch tube S4 is connected to the cathode - of the battery Vb, and the source S of the switch tube S4 is connected to the negative electrode - of the photovoltaic cell Vpv; the connection circuit forms a battery charging branch unit (3) for charging the battery Vb.

[0024] like Figure 2 As shown, FSBB-SL-TPC is the abbreviation of a wide input non-isolated three-port converter suitable for photovoltaic systems. In the SISO-B (battery Vb supplies power to the load alone) mode, in the SISO-B mode, the output voltage is stabilized by controlling the operation of switch tubes S4, S6, and S7.

[0025] When the photovoltaic cell is in the shadow area and moves to the weak light area, the FSBB-SL TPC converter is controlled to switch from the SISO-B mode to the DI (battery Vb and photovoltaic input power supply Vpv jointly powered mode) mode, and the output voltage is stabilized by the operation of the switch tubes S1, S2, S3, and S7.

[0026] When the photovoltaic cell is in a weak light area and moves to a strong light area, the FSBB-SL TPC converter is controlled to switch from DI mode to DO mode (the photovoltaic input power source Vpv supplies power to the battery Vb and the load).

[0027] When the photovoltaic cell is in a strong light area and the battery port is removed, the FSBB-SL TPC converter is controlled to switch from DO mode to SISO-P (the photovoltaic input power source Vpv supplies power to the load) mode. The output voltage is stabilized by controlling the switch tubes S1 and S6 to work.

[0028] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. The various components mentioned in the present invention are common technologies in the existing field. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only to illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection claimed by the present invention is defined by the attached claims and their equivalents.

Claims

1. A wide input non-isolated three-port converter suitable for photovoltaic systems, characterized in that The invention comprises a four-switch buck-boost conversion unit (1), a pulse voltage unit (2) and a battery charging branch unit (3), wherein the switch buck-boost conversion unit (1) is connected in parallel with the pulse voltage unit (2), the pulse voltage unit (2) is connected with the battery charging branch unit (3), the pulse voltage unit (2) is used to generate an access circuit for a battery Vb and form a discharge path for the battery Vb, and the battery charging branch unit (3) is used to generate a charging path for the battery Vb.

2. A wide input non-isolated three-port converter suitable for photovoltaic systems according to claim 1, characterized in that The four-switch buck-boost conversion unit (1) comprises a switch tube S1, a switch tube S2, an inductor L, a switch tube S6 and a diode VD2, wherein the drain D of the switch tube S1 is connected to the positive electrode of the photovoltaic input power source Vpv, the source S of the switch tube S1 is connected to the drain D of the switch tube S2, the source S of the switch tube S2 is connected to the negative electrode of the photovoltaic input power source Vpv, one end of the inductor L is connected to the drain D of the switch device S6, the anode A of the diode VD2 is connected to the drain D of the switch device S6, and the cathode K of the diode VD2 is connected to the positive electrode + of the output capacitor C. The above circuit connection is used for the discharge path of the photovoltaic input power source Vpv.

3. A wide input non-isolated three-port converter suitable for photovoltaic systems according to claim 1, characterized in that The pulse voltage unit (2) comprises a battery Vb, a switch tube S3, a switch tube S7, a diode VD1, and a diode VD3. The drain D of the switch tube S3 is connected to the anode A of the diode VD1, the source S of the switch tube S3 is connected to the negative electrode - of the battery Vb, the drain D of the switch tube S7 is connected to the cathode K of the diode VD1, the source S of the switch tube S7 is connected to the cathode K of the diode VD3, the anode A of the diode VD1 is connected to the drain D of the switch tube S3, the cathode K of the diode VD1 is connected to the drain D of the switch tube S7, the anode A of the diode VD3 is connected to the positive electrode + of the battery terminal Vb, and the cathode K of the diode VD3 is connected to the source S of the switch tube S7. The above connection method forms a pulse voltage unit (2) for a discharge circuit of the battery Vb.

4. A wide input non-isolated three-port converter suitable for photovoltaic systems according to claim 1, characterized in that The battery charging branch unit (3) comprises a switch tube S5, a diode VD4 and a switch tube S4, wherein the drain electrode D of the switch tube S5 is connected to the anode electrode A of the diode VD2, the source electrode S of the switch tube S5 is connected to the anode electrode A of the diode VD4, the cathode electrode K of the diode VD4 is connected to the positive electrode + of the battery Vb, the drain electrode D of the switch tube S4 is connected to the cathode electrode - of the battery Vb, and the source electrode S of the switch tube S4 is connected to the negative electrode - of the photovoltaic cell Vpv.

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