Novel three-phase photovoltaic grid-connected inverter system

[0028] Example 1, such as figure 1 As shown, there are two photovoltaic arrays, and when the output DC voltage levels are 500V and 700V respectively, each photovoltaic array is boosted by a DC circuit breaker 1, a DC EMI filter 2, and a BOOST boost circuit 3. And the controller 15 perform the maximum power tracking control of the BOOST boost circuit 3, boost the voltage to 960V, and then use the three-phase full-bridge IGBT inverter circuit 5 to perform three-phase inverter and grid-connected power generation, and the grid-connected voltage can be increased Above 620V, through the above structure, two different photovoltaic arrays can be connected to the grid together, which not only expands the maximum power point tracking range, but also improves the DC side voltage and inverter conversion efficiency.

[0029] Example 2, such as figure 2 As shown, there are three photovoltaic arrays, and when the output DC voltage levels are 500V, 700V, 900V, each photovoltaic array is boosted by a DC circuit breaker 1, a DC EMI filter 2, and a BOOST boost circuit 3. The controller 15 performs the maximum power tracking control of the BOOST boost circuit 3, boosts the DC side voltage to 960V, and then performs three-phase inverter grid-connected power generation through the three-phase full-bridge IGBT inverter circuit 5, and The grid voltage can be increased to above 620V. Through the above structure, three different photovoltaic arrays can be connected to the grid together, which not only expands the maximum power point tracking range, but also improves the DC side voltage and inverter conversion efficiency.

[0030] The sine filter 6 described in the above two embodiments uses an LCL sine filter to eliminate harmonics to obtain alternating current with the same frequency as the power grid.

[0031] The specific working principles of the present invention and the above two embodiments are as follows: the DC power converted by the photovoltaic array is integrated by the DC distribution box and then leads to each group of positive and negative DC output lines, and is input to the DC EMI filter 2 through the DC circuit breaker 1 for low pass. Filtering, eliminating the high frequency interference signal of DC, and realizing the protection of the DC distribution terminal, and then boosting each group of input DC voltage through the BOOST booster circuit 3, at the same time, the current and voltage detection module 12 detects the DC side voltage and current in real time , AC side voltage and current, through the power calculation of the controller 15 to complete the maximum power tracking of each BOOST booster circuit 3, the stable DC power is absorbed by the DC support capacitor 4 to absorb the ripple current and then sent to the three-phase full bridge IGBT Inverter circuit 5, and the three-phase full-bridge IGBT inverter circuit 5 is driven by the controller 15, and then the alternating current output by the three-phase full-bridge IGBT inverter circuit 5 is eliminated by the sinusoidal filter 6 to get the power grid The AC power of the same frequency is merged into the power grid after eliminating high frequency interference through the AC EMI filter 8.

[0032] In general, the output DC voltage levels of photovoltaic arrays on the market are as described above. The two embodiments described above have met most practical applications. If other photovoltaic arrays are to be connected in practice, those skilled in the art The need can be achieved based on the above technical enlightenment.

[0033] The parameters such as the output voltage of the photovoltaic array and the boosting of the DC power to the voltage level of 960V through the BOOST boost circuit 3 mentioned in the embodiment of the present invention are not as a limitation to the protection scope of the present invention, but are only a specific embodiment. Parameter setting. The invention protects a topological structure that can independently boost the output DC power of different photovoltaic arrays and then connect to the grid for power generation, which meets the combination of different photovoltaic arrays and has good compatibility. By using multiple sets of BOOST boost circuits 3 Multiple sets of different photovoltaic arrays are boosted, and the maximum power point tracking control of each BOOST booster circuit 3 is performed through the controller 15, which expands the maximum power point tracking range and greatly increases the DC side voltage, and then passes through an inverter Inverter grid-connected power generation saves costs and increases the grid-connected side voltage. At the same time, it satisfies different photovoltaic array combinations and different environmental requirements, and improves solar energy utilization and system power generation efficiency.