Inertia Estimation and Speed Loop Auto-Tuning for IPMSM Self-Commissioning

This paper presents a practical procedure regarding inertia estimation and speed loop auto-tuning for sensorless interior permanent-magnet synchronous motor (IPMSM) drives. In many applications, well-tuned speed controller is essential to enable dynamic and stable drive operations. However, high-performance speed controller design requires system parameters such as inertia which are unknown at the beginning of drive commissioning. Manual trial-and-error tuning is unattractive due to its blind, lengthy, non-optimal, and potentially unsafe nature. On the other hand, model-based tuning through inertia estimation has unique challenges at this step of self-commissioning. Determining the test torque for a safe and reasonably short test in inertia estimation is a real practical problem because the total inertia can be in wide range in different mechanical systems. Furthermore, feedback controllers are not usable to automatically determine the test torque due to unknown motor parameters. As a solution, this paper proposes an automated test torque selection procedure. Then it identifies the inertia and lastly tunes the speed controller using the identified parameter. Overall, a fully automated speed-loop auto-tuning method is proposed which aims minimal operator involvement. The findings are experimentally verified on an IPMSM drive. In addition, the proposed method can easily be extended to different motor types and sensored or sensorless vector control strategies.