A control method for a dual-frequency parallel three-phase grid-connected inverter
A control method and inverter technology, applied in the field of inverters, can solve problems such as limited efficiency, high switching frequency, and many components, and achieve the effects of improving efficiency and power density, reducing switching frequency, and reducing the volume of inductors
Active Publication Date: 2020-11-13
NORTH CHINA UNIVERSITY OF TECHNOLOGY
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Problems solved by technology
Therefore, the main problems of the LCL type three-phase grid-connected inverter are: many components, high cost, complex structure, difficult control, poor robustness, etc.
Finally, in order to ensure the filtering effect of the LCL filter, the inverter is required to work at a higher switching frequency, which limits the further improvement of efficiency
[0005] It can be seen that although the L-type and LCL-type three-phase grid-connected inverters can achieve harmonic suppression, they both have problems such as high switching frequency and limited efficiency improvement, and cannot be further improved by reducing the switching frequency. Inverter Efficiency
Method used
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[0043] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, wherein the schematic examples and descriptions are only used to explain the present invention, but not to limit the present invention.
[0044] Such as figure 1 As shown, a dual-frequency parallel three-phase grid-connected inverter described in this specific embodiment includes a housing, and a circuit board is arranged inside the housing, and the circuit board includes a control unit and a main circuit unit; the control The unit is connected to the main circuit unit through a signal;
[0045] The main circuit unit is composed of a low-frequency part and a high-frequency part; the low-frequency part includes a three-phase low-frequency power unit and a three-phase low-frequency filter, and the three-phase low-frequency power unit is connected in series with a three-phase low-frequency filter; the high-frequency Partly includes a three-phase ...
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The invention relates to the technical field of inverters, in particular to a control method for a dual-frequency parallel three-phase grid-connected inverter, which includes two coupled closed-loop control loops, and the two closed-loop control loops are coupled through a high-frequency compensation unit; two The coupled closed-loop control loops are high-frequency harmonic elimination control loop and low-frequency power control loop respectively; it reduces the inductance of the required power filter through a new topology structure, thereby reducing the size of the inductor and reducing the cost of the grid-connected inverter , simplify the control difficulty of grid-connected inverters, reduce the switching frequency of high-power switching devices, and improve the efficiency and power density of grid-connected inverters.
Description
【Technical field】 [0001] The invention relates to the technical field of inverters, in particular to a control method for a dual-frequency parallel three-phase grid-connected inverter. 【Background technique】 [0002] The inverter is a device that converts DC power (battery, storage battery) into AC power (generally 220V, 50Hz sine wave). It consists of an inverter bridge, control logic and filter circuit. Three-phase PWM grid-connected inverter technology is the main device that converts DC power into three-phase AC power and transmits it to the grid. Generally, self-shutdown power devices are required. Since the grid-connected regulations have strict requirements on the harmonics of the grid-connected current, it is necessary to take measures to suppress the current harmonics to reduce the pollution to the grid. Generally, the higher the switching frequency of the power device, the smaller the harmonic of the grid-connected current. However, in order to reduce the loss of ...
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IPC IPC(8): H02M7/48H02M1/12H02J3/38
CPCH02J3/38H02M1/126H02M7/48H02M1/0054Y02B70/10
Inventor 杨立永
Owner NORTH CHINA UNIVERSITY OF TECHNOLOGY