Finite Control Set Model Predictive Direct Power Control of Single-Phase Three-Level PWM Rectifier Based on Satisfactory Optimization

Xu Zhang,Zhan Liu,Qiang Wang,Weifeng Zhang,Guojun Tan,Tao Xia

doi:10.1109/access.2021.3049279

Abstract

In this paper, a finite control set model predictive direct power control (FCS-MPDPC) method based on satisfactory optimization, for single-phase three-level PWM rectifier, is proposed to achieve global optimization that takes into account all its objectives and constraints. Satisfaction optimization aims to obtain the satisfactory solution after coordination of multiple goals, instead of the optimal solution of a single goal. By replacing “optimal” with “satisfaction”, more control degrees of freedom are acquired, so that low-priority auxiliary control objectives can participate in the optimization process. Meanwhile, in order to enhance the description accuracy of FCS-MPDPC method for the future trend of PWM rectifier, the prediction time domain is extended from the traditional single-step to multi-step, and the average switching frequency model is established to realize the low switching frequency control. The satisfactory optimized FCS-MPDPC method proposed in this paper is compared, through simulation and experimental results, with the standard FCS-MPDPC method, which verifies the effectiveness and superiority of the proposed algorithm.

Highlights

The single-phase PWM rectifier converter can realize the bidirectional flow of electric energy, and maintain high power factor and small current distortion (THD) between the AC and DC output terminals
Single-phase three-level PWM converters are widely used in high-speed railway traction [5]
In [34], the NPC single-phase three-level PWM rectifier is used as the control object, and the single-step Finite control set model predictive control (FCS-MPC) method is studied and introduced

Summary

INTRODUCTION

The single-phase PWM rectifier converter can realize the bidirectional flow of electric energy, and maintain high power factor and small current distortion (THD) between the AC and DC output terminals. In [34], the NPC single-phase three-level PWM rectifier is used as the control object, and the single-step FCS-MPC method is studied and introduced. The cascading-free prediction method further improves the DC-side dynamic performance of the single-phase three-level PWM rectifier, but its cost function contains only two control targets of current error and midpoint potential deviation, and does not introduce switching frequency optimization control. The reasons are as follows: 1) Multiple targets and constraints of single-phase threelevel PWM rectifiers often have different measurement units and accuracy requirements (such as power unit is watt, voltage unit is volt, and switching frequency unit is Hertz), and there are even certain time-varying and conflicting feature(such as steady-state error and switching frequency); 2) The single-step Np=1 prediction link of traditional FCS-MPC method is extremely limited in the description of the future trend of single-phase three-level PWM rectifier. The results verify the effectiveness and superiority of the proposed algorithm

Prediction Model

Medium Priority

Findings

Low Priority