Composite control method of T-type three-level NPC inverter

Abstract

The invention discloses a composite control method for a T-type three-level NPC inverter, and the method employs improved model prediction control, and employs two-step prediction to replace conventional one-step prediction: obtaining a tk + 1 moment prediction value through sampling calculation at a tk moment, and further predicting a tk + 2 moment prediction value through employing the tk + 1 moment prediction value as a measurement value on the basis of the tk + 1 moment prediction value; selecting the optimal switching state combination by using the cost function and acts on the tk + 1 moment, so that the switching state combination at the tk + 1 moment is determined at the tk moment; directly adjusting the neutral-point potential through repeated control, so that the neutral-point voltage of the T-type three-level NPC inverter is balanced, and the complex parameter adjustment process is avoided. According to the invention, the grid connection of the inverter is more accurate, andcompared with other traditional control methods, the method can eliminate high-frequency harmonic waves caused by the imbalance of the power grid, does not need positive and negative sequence separation, can achieve a better control effect, and effectively reduces the impact on the system from delay.

Description

technical field [0001] The invention belongs to the technical field of three-level inverters, and in particular relates to a compound control method for a T-type three-level NPC inverter. Background technique [0002] The three-level diode-clamped (NPC) inverter has become a commonly used three-level topology because of its simple control. However, the loss distribution of each power switch tube of the NPC inverter is uneven, which will lead to uneven temperature distribution under high-frequency switching, which will reduce the reliability of the inverter. To solve this problem, T-type three-level NPC inverters are widely used. At the same time, the T-type three-level NPC inverter topology has a good application prospect in the industrial field due to its advantages of small size, low cost, low loss, and high efficiency. [0003] With the rise of new energy power generation, a large number of new energy power generation is connected to the grid, and the requirements for g...

AI Technical Summary

Problems solved by technology

However, the model predictive control method it adopts is single-step prediction, which has the disadvantage of time delay.

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