Delay Analysis and Predictive Compensation of Digital Control of Traction System

Abstract

Digital control is widely used in traction system of high-speed train, where digital control delay is large and inevitable owing to the low switching frequency of traction converter. The digital control delay changes the phase characteristics of the traction system, which will affect the stability of the train-grid system. Focusing on the digital control delay of the traction system, this paper establishes impedance model of traction system with digital delay to analyze the impact of delay on system stability, where the generation mechanism and value of digital control delay are derived under different sampling frequency and switching frequency in detail. In addition, a prediction compensation algorithm that is simple to implement and does not rely on the system model is proposed to diminish the digital delay. Finally, the simulation results verify the correctness of theoretical analysis and the validity of proposed method.