Permanent Magnet Synchronous Motor Drive Control for High-Temperature Downhole Formation Sampling: Design and Experimental Validation

Abstract

Downhole formation sampling requires stable motor control under high temperature and strong vibration. This paper presents an integrated permanent magnet synchronous motor (PMSM) control-drive system for a compact downhole sampling tool. The system combines miniaturized hardware, resolver-based feedback, field-oriented control, and an improved fuzzy two-degree-of-freedom PI speed controller to enhance low-speed stability and turn-count accuracy. Experiments were carried out under no-load, load, high-temperature, and vibration conditions. Results show that the system operates reliably at 150 °C and 20 g vibration, with steady-state speed error below 1% full scale and full-scale relative turn-count error below 0.5%. The proposed design provides a practical high-temperature motor-drive solution for downhole formation sampling tools.