Speed Control Strategy of Low-Cost Modular Permanent Magnet Synchronous Linear Motor Based on Sliding Mode Vector Tracking Observer

In order to achieve the low-cost position detection of modular permanent magnet synchronous linear motor (MPMSLM), three switching Hall sensors space 120° apart are designed. Two groups of Hall detection board are installed to ensure the position detection is effective throughout the process. The motor speed and electrical angle are extracted from Hall signals using Taylor expansion. In addition, a sliding mode observer (SMO) is designed to estimate the back EMF. Then, the information of SMO and Hall sensors is integrated by vector tracking observer. Eventually, a closed-loop speed control system based on sliding mode vector tracking observer is established. The experiments are carried out on the linear segment of MPMSLM. The results show that the proposed method can estimate motor speed and electrical angle accurately at the full-speed range.