Model prediction control method for three-level voltage-source-type converter

Abstract

The invention belongs to the control field of electric power electron converters and relates to a model prediction control method for a three-level voltage-source-type converter. The model prediction control method for the three-level voltage-source-type converter comprises the following steps: step one, building models of relations between currents of the alternating current side of the three-level voltage-source-type converter and switch functions; step two, building models of relations between capacitance voltage offsets of the direct current side and switch functions; step three, obtaining current instruction values through outer voltage loops and obtaining a current instruction value of the next moment by calculating current instruction values of several moments before; step four, setting value functions of a model prediction control algorithm for the three-level voltage-source-type converter; step five, calculating on-off state subsets; step six, achieving real-time prediction control. The model prediction control method for the three-level voltage-source-type converter is simple in algorithm, easy to achieve and capable of being adopted in a higher-level converter, and has generality.

Description

technical field [0001] The invention relates to a control method for a mid-point clamp type three-level voltage source converter, which belongs to the control field of power electronic converters. Background technique [0002] The neutral point clamped (NPC) three-level voltage source converter can flow bidirectionally with its power, the power grid side can realize unity power factor operation, the input current has good sine degree, the harmonic distortion is small, and the device is under pressure It has many advantages such as low switching frequency, low du / dt, etc., and has been widely used in the fields of high-power AC speed regulation, high-voltage direct current transmission and new energy power generation. [0003] The control strategy of the three-level voltage source converter usually includes a current inner loop control strategy. The main goal of the current inner loop control is to quickly track the current command and make the input current sinusoidal. Bec...

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Problems solved by technology

However, this method has the following problems: (1) Due to the large number of switching vectors of the three-level converter and the complexity of the value function, the calculation amount of the program is relatively large, which limits the improvement of the sampling frequency of the control system and restricts the overall Improvement of control performance; (2) When the switching state is switched, the phase voltage and the line voltage have an excessively high amplitude jump, and the single tube bears the entire bus voltage or the load end is subjected to an excessively high voltage impact. Therefore, to solve the above problems, it is necessary to modify the traditional The model predictive control method is improved, so that the amount of calculation is reduced, and there will be no excessive jumps in the line voltage or phase voltage amplitude when the switch state is switched

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