A Model Predictive Direct Power Control Method for Three-Level Inverter

Abstract

The invention discloses a model-predicted direct power control method for a three-level inverter, which calculates the collected grid current, grid voltage, DC side current, and DC positive and negative capacitor voltages to obtain a power error vector, and obtains a power error vector by superimposing the error The sector information is obtained from the phase angle of the vector and the grid voltage vector, and the combination of alternative vectors to be used in the current beat is obtained from the obtained sector information, and the switch control signal is generated in the PWM module by the optimal switch vector to control the three-level inverter The on-off of each power switch tube of the device; the method of the present invention selects a specific switch vector combination according to the sector information where the power error vector is calculated, and calculates and compares the cost function value with the switch vector in the selected switch vector combination, thereby The optimal switch control signal is obtained, the method has good steady-state performance, and can quickly track the amplitude step change of the power command.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a model predictive direct power control method of a three-level inverter. Background technique [0002] In power energy consumption and new energy power generation systems, power electronic equipment with inverters as the core, as a bridge for energy conversion, plays a vital role in ensuring the smooth flow of energy and achieving high-quality power supply. Compared with the traditional two-level inverter, the three-level inverter has the advantages of high withstand voltage level, low voltage distortion rate and small harmonic content. At the same time, its level number is moderate and easy to implement, so it has been widely studied and applied. The direct power control method is one of the most commonly used control methods for inverters to realize power decoupling control. This method has a simple control structure, does not require current control in...

AI Technical Summary

Problems solved by technology

However, the control effect of the traditional direct power control method depends heavily on the accuracy of its switch vector table, resulting in the inherent disadvantage of low steady-state accuracy.

In order to solve the problem of low steady-state accuracy of the traditional direct power control method, scholars at home and abroad have proposed many improved methods, including a new switch vector table and a combination of space vector modulation technology, etc.

Although these methods can improve their steady-state performance to a certain extent, they also increase the complexity of the algorithm

In addition, because the three-level topology also has the control requirements of the midpoint potential balance control, the design of the switch vector table is more complicated

[0003] The introduction of model predictive control into the direct power control method provides a new idea to effectively solve the problem of low steady-state accuracy. At present, there have been a large number of related research results for two-level inverters, and they can be well solved. this problem

However, the three-level inverter still has the inherent problem of midpoint balance, and there are few related researches.

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