CN216599433U - Bidirectional DC-DC circuit of grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system - Google Patents
Bidirectional DC-DC circuit of grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system Download PDFInfo
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- CN216599433U CN216599433U CN202122997167.8U CN202122997167U CN216599433U CN 216599433 U CN216599433 U CN 216599433U CN 202122997167 U CN202122997167 U CN 202122997167U CN 216599433 U CN216599433 U CN 216599433U
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Abstract
The utility model discloses a bidirectional DC-DC circuit of a grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system, which comprises a DAB circuit and an interleaved buck/boost circuit, wherein the two circuits are connected in parallel, the two circuits of the DAB circuit have the same structure, the DAB circuit consists of a high-frequency transformer, a rectifier bridge on the low-voltage side of the high-frequency transformer and a rectifier bridge on the high-voltage side, and the rectifier bridge on the low-voltage side is connected with an energy storage battery; the staggered buck/boost circuit comprises two groups of current Hall sensors, and the two groups of current Hall sensors are respectively connected with the two groups of DAB circuits. The utility model adopts a DAB circuit structure with two parallel circuits to reduce the current stress of a switching tube, utilizes a variable voltage leakage inductance and a high-voltage side capacitor to form a resonant cavity, sets the switching frequency to be slightly lower than the resonant frequency, enables the circuit to work in an under-resonance state, avoids the reverse recovery loss of the primary side and the secondary side of a transformer in the charging and discharging process, and improves the system efficiency and the dynamic performance.
Description
Technical Field
The utility model relates to the related technical field of photovoltaic energy storage, in particular to a bidirectional DC-DC circuit of a grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system.
Background
Grid-connected solar photovoltaic power generation refers to a mode of connecting solar photovoltaic power generation with a national power grid to generate power, and becomes a supplement of the power grid, and is typically characterized in that a storage battery is not needed. However, because the existing new energy power generation systems such as photovoltaic and wind power generation systems are low in reliability and smart power grids are not established, in order to ensure that the power generated by the photovoltaic power generation systems is directly supplied to local loads without being fed to the power grids, a grid-connected and off-grid type photovoltaic energy storage inversion control system needs to be added into the new energy power generation systems, and grid-connected and off-grid operation and grid-connected and off-grid switching are realized at the same time.
In the framework of the grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system, the bidirectional DC-DC circuit is used for fine adjustment of low-voltage direct-current side voltage. The current common bidirectional DC-DC circuit has the problem of reverse recovery loss during charging and discharging, and the system efficiency is reduced.
Disclosure of Invention
The utility model aims to provide a bidirectional DC-DC circuit of a grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system, so as to solve the problems in the background art.
In order to achieve the purpose, the utility model provides the following technical scheme:
a bidirectional DC-DC circuit of a grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system comprises a two-way parallel DAB circuit and a staggered buck/boost circuit, wherein the two-way DAB circuit has the same structure and consists of a high-frequency transformer, a rectifier bridge on the low-voltage side of the high-frequency transformer and a rectifier bridge on the high-voltage side, and the rectifier bridge on the low-voltage side is connected with an energy storage battery; the staggered buck/boost circuit comprises two groups of current Hall sensors, and the two groups of current Hall sensors are respectively connected with the two groups of DAB circuits.
As a further scheme of the utility model: the rectifier bridge consists of four rectifier diodes.
As a further scheme of the utility model: and the rectifier bridge at the low-voltage side is connected with the primary side of the high-frequency transformer in an anti-parallel mode.
As a further scheme of the utility model: the transformation ratio of the high-frequency transformer is 1: 6.
Compared with the prior art, the utility model has the beneficial effects that: the utility model adopts a DAB circuit structure with two parallel circuits to reduce the current stress of a switching tube, utilizes a variable voltage leakage inductance and a high-voltage side capacitor to form a resonant cavity, sets the switching frequency to be slightly lower than the resonant frequency, enables the circuit to work in an under-resonance state, avoids the reverse recovery loss of the primary side and the secondary side of a transformer in the charging and discharging process, and improves the system efficiency and the dynamic performance.
Drawings
Fig. 1 is a schematic circuit diagram of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, in an embodiment of the present invention, a bidirectional DC-DC circuit of a grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system includes a two-way parallel DAB circuit and an interleaved buck/boost circuit, where the two-way DAB circuit has the same structure, the DAB circuit includes a high-frequency transformer with a transformation ratio of 1:6, a rectifier bridge on a low-voltage side of the high-frequency transformer, and a rectifier bridge on a high-voltage side, the rectifier bridge includes four rectifier diodes, the rectifier bridge on the low-voltage side is connected in anti-parallel with a primary side of the high-frequency transformer, the rectifier bridge on the low-voltage side is connected to an energy storage battery, a first-stage DAB circuit boosts a voltage of 48V on a low-voltage direct-current side to a voltage of approximately 300V on a medium-voltage direct-current side, and a parallel structure is adopted to reduce a current stress of a switching tube. A resonant cavity is formed by the transformation leakage inductance and the high-voltage side capacitor, and the switching frequency is set to be slightly lower than the resonance frequency, so that the circuit works in an under-resonance state. In this state, when the energy storage battery discharges, the primary side field effect tube can realize zero current turn-off, and the secondary side anti-parallel rectifier diode can realize natural turn-off without reverse recovery loss; when the energy storage battery is charged, the secondary side rectifier bridge can realize zero current turn-off, the primary side anti-parallel rectifier diode can realize natural turn-off, reverse recovery loss does not exist, the field effect tube can work in a synchronous rectification state, the conduction loss of the primary side switch tube is reduced, and therefore efficiency is further improved. The resonance current is detected through current transformers CT1 and CT2 to realize overcurrent protection;
the second-stage staggered Buck/boost circuit comprises two groups of current Hall sensors CS1 and CS2, wherein the two groups of current Hall sensors are respectively connected with the two groups of DAB circuits, 300V on a medium-voltage direct-current side is increased to 400V rated voltage of a high-voltage direct-current bus to stabilize the voltage of the high-voltage direct-current bus, and Buck/boost inductive current is detected through the current Hall sensors to realize voltage-current double closed-loop control and improve the dynamic performance of the system.
It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.
Claims (4)
1. A bidirectional DC-DC circuit of a grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system is characterized in that: the DAB circuit comprises a two-way parallel DAB circuit and a staggered buck/boost circuit, wherein the two-way DAB circuit has the same structure, the DAB circuit consists of a high-frequency transformer, a rectifier bridge on the low-voltage side of the high-frequency transformer and a rectifier bridge on the high-voltage side of the high-frequency transformer, and the rectifier bridge on the low-voltage side is connected with an energy storage battery; the staggered buck/boost circuit comprises two groups of current Hall sensors, and the two groups of current Hall sensors are respectively connected with the two groups of DAB circuits.
2. The bidirectional DC-DC circuit of the grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system according to claim 1, wherein: the rectifier bridge consists of four rectifier diodes.
3. The bidirectional DC-DC circuit of the grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system according to claim 1 or 2, wherein: and the rectifier bridge at the low-voltage side is connected with the primary side of the high-frequency transformer in an anti-parallel mode.
4. The bidirectional DC-DC circuit of the grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system according to claim 1, wherein: the transformation ratio of the high-frequency transformer is 1: 6.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122997167.8U CN216599433U (en) | 2021-12-01 | 2021-12-01 | Bidirectional DC-DC circuit of grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122997167.8U CN216599433U (en) | 2021-12-01 | 2021-12-01 | Bidirectional DC-DC circuit of grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system |
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| Publication Number | Publication Date |
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| CN216599433U true CN216599433U (en) | 2022-05-24 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202122997167.8U Active CN216599433U (en) | 2021-12-01 | 2021-12-01 | Bidirectional DC-DC circuit of grid-connected and off-grid dual-mode single-phase photovoltaic energy storage system |
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2021
- 2021-12-01 CN CN202122997167.8U patent/CN216599433U/en active Active
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