Abstract
Control techniques for Permanent Magnet Synchronous Motor (PMSM) drives rely significantly on digital systems, and control system discretization is essential for stability and robustness. While continuous-time analyses are widely employed for stability analysis, generally, they fall short of describing phenomena such as the waterbed effect and understanding system dynamics, especially in servo-drive applications. Consequently, discrete-time systems play a crucial role. The use of discrete-time analysis in digital motion systems of control allows for a more accurate study of system stability while addressing the abovementioned difficulties. Despite the vital role of discrete-time analysis in maximizing stability, robustness, and performance in digital PMSM implementations, there is a significant research gap in the complete analysis and investigation of discrete-time control systems. This research focuses on improving digital disturbance observer (DOB)-based speed control via discrete-time analysis by investigating various discretization techniques. Analyzing widespread discrete-time approaches that rely on analog-to-digital time conversion demonstrates that some strategies outperform others. The paper indicates that constructing a digital DOB-based control utilizing the implicit Adams approach and applying it to PMSMs enhances performance by increasing control accuracy and significantly reducing undershoot when compared to popular discrete-time methods such as Euler’s, Tustin, Al-Alaoui, and others. The experimental results show that this chosen discrete-time approach has a significant impact on the efficiency of the PMSM control system. The outcomes of this research highlight the critical relevance of selecting an appropriate discrete-time conversion in improving the performance of a digital DOB motion control system with an application to PMSM drives.