A Simple Model Predictive Instantaneous Current Control for Single-Phase PWM Converters in Stationary Reference Frame

The traditional proportional-integral (PI) based current control for single-phase pulsewidth-modulation (PWM) converters in railway traction applications either has a steady-state error or a poor dynamic response. Deadbeat instantaneous current control (ICC) cannot eliminate the steady-state error due to approximation errors of the linear extrapolation. Compared with PI-based direct current control, continuous-control-set (CCS) model predictive control (MPC) implemented in a d-q frame offers better performance, but its dynamic response is still slower than ICC. To solve these problems, a simple model predictive (MP) ICC scheme for single-phase PWM converters is proposed in this article. The optimal modulation function is calculated in the stationary reference frame by the CCS-MPC principle without beta-axis current estimation and reference frame transformation. The proposed MP-ICC scheme can keep the fast dynamic response characteristics of ICC and achieve zero steady-state error. In addition, it has the advantages of low current harmonics and low computational complexity. The influence of the inductance parameter mismatch on the current loop is analyzed in detail, and a phasor-method-based inductance parameter online estimation is developed. This solution can be executed during the idle time of the digital processor without making the control delay longer. Finally, a comprehensive experimental comparison with four existing current control schemes is conducted to verify the feasibility and effectiveness of the proposed scheme.

Automated summary

This article proposes a simple MP-ICC scheme for single-phase PWM converters in railway traction applications, aiming to achieve fast dynamic response and zero steady-state error, with the advantages of low current harmonics and low computational complexity. The proposed scheme is compared with four existing current control schemes through comprehensive experimental comparison to verify its feasibility and effectiveness.