OPTIMIZATION OF A DIGITAL CURRENT CONTROL SYSTEM FOR AN ELECTRIC DRIVE WITH A THYRISTOR CONVERTER
Authors: VOZNIAK Oleksandr , TIKHONENKO Serhii , TYKHONOV Volodymyr , KOSAKOVSKYI Artem 
Published: January 2025

The article is dedicated to optimizing the digital current control loop of a thyristor converter-driven electric drive, essential for ensuring stable, precise, and reliable operation of electric drives in automated and industrial systems. The primary goal of this research is to develop and enhance the digital current regulator (DCR), which enables the drive system to achieve desired performance, including rapid and stable response to current changes without excessive overshoot or oscillations. Optimization of the current loop improves energy efficiency, enhances dynamic properties, and increases resistance to external disturbances, all of which are critical for modern electric drive systems.
The introduction discusses key aspects of digital current loop optimization, specifically dynamic characteristics such as time delays, sampling rate, and bandwidth, which significantly impact the efficiency of digital controllers. Special attention is given to the tuning of proportional-integral (PI) controller parameters, allowing quick and stable response to current changes. The developed model allows preliminary simulation of the current loop’s performance, providing an opportunity to test different configurations before actual implementation.
To improve the accuracy and stability of the system, filtering methods are proposed to reduce the impact of high-frequency noise, ensuring the system’s precision and robustness against external interference. Optimization criteria are introduced, including minimizing the integral square error (ISE) and reducing energy consumption, which significantly decreases system losses and increases the energy efficiency of electric drives.
In developing the optimized control loop, the following assumptions are considered: 1) the thyristor converter (TC) operates in continuous current mode, 2) the current loop dynamics are studied within a narrow range of TC phase angle changes, and 3) a discrete dynamic TC model is used with averaging of electromotive force (EMF) over the conduction interval. Optimizing the digital current loop addresses several critical tasks, including enhancing control accuracy, reducing overshoot and oscillations, and improving the system’s dynamic response, allowing for reduced delays and a faster reaction to load changes.
The optimization results of the digital current regulator (DCR) show reduced energy consumption and significant improvements in control accuracy. The high-speed performance of the digital current loop enables fast transient processes within a single sampling interval of the thyristor converter, which is crucial for systems requiring rapid regulation. Additionally, the digital control loop provides flexibility in control, as it allows for system adjustments to different operating conditions through a software-based approach.
The study’s final results demonstrate the potential of digital current loops in modern electric drives. With advances in microprocessor technology, digital regulators enable more complex control algorithms, including adaptive and predictive strategies, which further enhance system efficiency. These approaches are especially relevant for industrial electric drives that require high precision and response speed, making digital current loops a promising solution for contemporary automated control systems.