Novel fixed frequency model predictive current control method based on dynamic weight

Abstract

The invention belongs to the field of power converter control, and relates to a novel fixed frequency model predictive current control method with a dynamic variable weight. The method controls a system according to an equivalent switching circuit of a triple converter and an integrated control theory. Traditional fixed frequency model predictive current control accurately calculates a voltage vector needed at a next moment according to a discrete mathematical model of the system, thereby achieving the characteristic of fast response in a dynamic process. Due to the influence of double frequency fluctuation of DC bus voltage in a triple converter system, high control performance is not available in a steady-state process, but a proportional resonant (PR) control algorithm can realize AC signal tracking without static error in the steady-state process, but a PR control algorithm has the defect of control adjustment lag in the dynamic process. The advantages of the two control algorithmsare combined, the PR control algorithm is used as a compensating link of model predictive current control, novel fixed frequency model predictive current control based on dynamic variable weight is constructed, and a time-varying weight function m is designed according to a Gauss distribution function in a bell curve based on a d-axis current error value. According to the change rule of the function m, the two algorithms can be smoothly switched, thereby lowering the influence of frequency doubling fluctuation in DC bus voltage on the performance of a control system, and ensuring that the control system has high performance in both dynamic and steady-state processes.

Description

technical field [0001] The invention belongs to the field of power converter control, and relates to a novel fixed-frequency model predictive current control method based on dynamic weight, which can be applied to the fields of motor speed regulation, renewable energy power generation, and the like. Background technique [0002] With the improvement of the power level of the permanent magnet synchronous motor system, the topology composed of traditional power devices can no longer meet the requirements of high voltage and high power applications. In order to meet the actual engineering needs, researchers at home and abroad use multiple converter technology to combine the traditional two-level six-switch topology to form a multiple converter topology. Due to the characteristics of the topology itself, the bus voltage of the multiple converter structure has double frequency fluctuations when the system is running. Therefore, when controlling the system, if the traditional fix...

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Problems solved by technology

Therefore, when controlling the system, if the traditional fixed-frequency model is used to predict the current control, when the mathematical model of the system is accurate, it has the ability to respond quickly, but it cannot weaken the influence of the bus voltage fluctuation on the control performance in the steady state. The proportional resonance control (Proportional Resonant, referred to as PR) can realize the AC signal without static error tracking. Therefore, the PR control algorithm can weaken the influence of the bus voltage fluctuation on the control performance. However, the PR control algorithm has the disadvantage of adjustment lag in the dynamic process.

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