Three-level PWM rectifier model prediction control method

Abstract

The invention discloses a three-level PWM rectifier model prediction control method. The method includes: firstly, establishing a three-level PWM rectifier discrete prediction model, and performing state sampling on a PWM rectifier system; then predicting the state of the PWM rectifier system according to the discrete prediction model to obtain a corresponding predicted value and an expected value; calculating a value function value corresponding to each switching state, comparing the value function values one by one, and obtaining the switching state corresponding to a minimum value functionthrough screening and comparison, wherein the corresponding switching state thereof is the optimal solution of the FCS-MPC. According to the control method, the dynamic and steady-state performances of the system can be effectively enhanced, the output quality of the PWM rectifier is high, the perfectness and the adaptability of offline planning are high, the switching frequency of the system canbe effectively reduced, and the switching loss is greatly reduced.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a model predictive control method for a three-level PWM rectifier. Background technique [0002] The PWM rectifier is a necessary component for the power variable frequency drive to be connected to the power grid, and it can realize the two-way transmission of the power grid and the motor load energy. At present, the main solutions of the PWM rectifier system are roughly divided into two categories: "vector control" and "direct power control". Power regulation is the only indicator, ignoring the multiplicity of PWM rectifier design indicators in actual use; specifically, the "vector control" solution adopts a multi-loop structure, the inner and outer loop stability margins are cross-coupled, and any loop Oscillation or instability will cause the output quality of the PWM rectifier to decline, and even affect the normal operation of the PWM rectifier. The optimization index of t...

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Problems solved by technology

At present, the main solutions of the PWM rectifier system are roughly divided into two categories: "vector control" and "direct power control". Power regulation is the only indicator, ignoring the multiplicity of PWM rectifier design indicators in actual use; specifically, the "vector control" solution adopts a multi-loop structure, the inner and outer loop stability margins are cross-coupled, and any loop Oscillation or instability will cause the output quality of the PWM rectifier to decline, and even affect the normal operation of the PWM rectifier. The optimization index of the frequency conversion system is not fixed; at this time, the off-line planning shows the disadvantages of lack of perfection and poor adaptability; moreover, the various indexes and constraints of the PWM rectifier are not independent and decoupled. There are serious conflicts and contradictions. The two pursue excessively the optimization of the output power of the PWM rectifier, which makes the PWM rectifier easy to fall into the misunderstanding of local optimum.

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