CN201270420Y - Starting circuit for photovoltaic grid connected inverter - Google Patents

Abstract

The utility model discloses a start-up circuit of a photovoltaic grid-connected inverter, aiming to provide a start-up circuit of a photovoltaic grid-connected inverter which can prevent the photovoltaic grid-connected inverter from repeatedly starting and stopping in a "critical state". The utility model comprises a starting circuit (1), a grid-connected inverter (2) and a solar battery group (3), the grid-connected inverter (2) is connected in parallel with the solar battery group (3), and the starting circuit ( 1) It includes several power resistors and an electronic switch, the several power resistors are connected in series with the electronic switch after being connected in parallel, and the power resistors and electronic switches connected in series are connected in parallel with the solar cell group (3). The utility model can avoid the starting circuit of the photovoltaic grid-connected inverter repeatedly starting and stopping in the "critical state". It can be widely used in solar photovoltaic grid-connected inverter circuits.

Description

A start-up circuit for a photovoltaic grid-connected inverter

technical field

The utility model relates to a starting circuit of a photovoltaic grid-connected inverter.

Background technique

In today's energy shortage, the use of solar energy is becoming more and more extensive. Solar cells use solar energy to generate electrical energy for use in power supplies, and the generated electrical energy can also be stored or sent to photovoltaic grid-connected inverters for integration into the grid. Currently, this is used However, when the sunlight received by the solar cell is weak, the generated electric potential can start the grid-connected inverter, but it cannot reach the energy required by the load, and the electric potential drops rapidly, causing the grid-connected inverter This state is often defined as a "critical state". This "critical state" repeatedly causes the grid-connected inverter to be switched on and off multiple times in a short period of time, which may easily cause the grid-connected inverter to fail.

To sum up, the photovoltaic grid-connected inverter in the prior art has the defect of repeatedly starting and stopping in a "critical state".

Utility model content

The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide a start-up circuit of the photovoltaic grid-connected inverter that can avoid repeated start-up and stop of the photovoltaic grid-connected inverter in a "critical state".

The technical solution adopted in the utility model is: the utility model includes a starting circuit, a grid-connected inverter and a solar cell group, and the grid-connected inverter mainly includes a DC filter, an inverter and an AC filter connected to each other , the grid-connected inverter is connected in parallel with the solar battery group, and the grid-connected inverter can also be a solar battery grid-connected inverter system in which a microcomputer monitoring unit controls multiple power modules, and the starting circuit includes several A power resistor and an electronic switch, the power resistors connected in parallel are connected in series with the electronic switch, and the series connected power resistors and electronic switch are connected in parallel with the solar cell group.

The electronic switch may be composed of an electronic circuit, a transistor, and a switch tube, or may be composed of a control circuit, a relay, and a contactor.

The beneficial effects of the utility model are: since the utility model includes a starting circuit, a grid-connected inverter and a solar cell group, the grid-connected inverter mainly includes a DC filter, an inverter and an AC filter connected to each other, The grid-connected inverter is connected in parallel with the solar battery group, and the grid-connected inverter can also be a solar battery grid-connected inverter system in which a microcomputer monitoring unit controls multiple power modules, and the starting circuit includes several power A resistor and an electronic switch, the power resistors connected in parallel are connected in series with the electronic switch, and the series connected power resistors and electronic switch are connected in parallel with the solar cell group. The electronic switch may be composed of an electronic circuit, a transistor, and a switch tube, or may be composed of a control circuit, a relay, and a contactor. Therefore, the utility model is a starting circuit of a photovoltaic grid-connected inverter that can prevent the photovoltaic grid-connected inverter from repeatedly starting and stopping in a "critical state".

Description of drawings

Fig. 1 is a block diagram of the utility model application circuit;

Fig. 2 is the starting circuit schematic diagram that the utility model control circuit and contactor form;

Fig. 3 is a schematic diagram of a start-up circuit composed of an electronic circuit and a switching tube of the utility model.

Detailed ways

As shown in Fig. 1, Fig. 2 and Fig. 3, the utility model includes a starting circuit 1, a grid-connected inverter 2 and a solar cell group 3, and the grid-connected inverter 2 mainly includes a DC filter connected to each other, an inverter Inverter and AC filter, the grid-connected inverter 2 is connected in parallel with the solar battery group 3, and the grid-connected inverter 2 can also be a solar battery grid-connected inverter controlled by a microcomputer monitoring unit to control multiple power modules The starting circuit 1 includes a plurality of power resistors and an electronic switch, the plurality of power resistors are connected in series with the electronic switch, and the series connected power resistors and the electronic switch are connected with the solar cell group 3 in parallel.

The electronic switch may be composed of an electronic circuit, a transistor, and a switch tube, or may be composed of a control circuit, a relay, and a contactor.

The utility model connects a fixed load to both ends of the solar cell group 3 by automatically opening the start-up circuit 1 before the grid-connected inverter 2 starts to output. When the sunlight is too weak, due to the fixed load The inverter system cannot be started when the output voltage at both ends of the connected battery pack 3 is too low. After the output voltage at both ends of the solar battery pack 3 reaches the operating voltage of the grid-connected inverter 2, the grid-connected inverter 2 will start again. Start the output and turn off the fixed load at the same time to improve the efficiency. The utility model is a starting circuit of the photovoltaic grid-connected inverter that can avoid the repeated start and stop of the photovoltaic grid-connected inverter in the "critical state". It can be widely used in solar photovoltaic grid-connected inverter circuits.

Claims (2)

1, a kind of start-up circuit of photovoltaic combining inverter, it comprises start-up circuit (1), combining inverter (2) and solar battery group (3), described combining inverter (2) mainly comprises interconnective DC filter, inverter and alternating current filter, described combining inverter (2) is in parallel with described solar battery group (3), described combining inverter (2) also can be the solar cell combining inverter system of many power models of 1 micro computer monitoring unit controls, it is characterized in that: described start-up circuit (1) comprises some power resistors and an electronic switch, connect with described electronic switch after described some power resistor parallel connections, power resistor after the described series connection and described electronic switch are in parallel with described solar battery group (3).

2, according to the start-up circuit of the described a kind of photovoltaic combining inverter of claim 1, it is characterized in that: described electronic switch can be made up of electronic circuit and transistor, switching tube, also can be made up of control circuit and relay, contactor.

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