Research On Thermal Behavior And Thrust Force Of Water-cooled Permanent Magnet Linear Motor

The water-cooled permanent magnet linear motors (PMLMs) can be applied in high-speed precision devices, such as CNC machine tools, semiconductor manufacturing tools and so on, due to their advantages of high acceleration, high speed, high precision etc. It is the research focus in the field of linear motors. After studying literatures, this thesis completes the following researches for two kinds of water-cooled PMLMs:To a single-sided water-cooled12-slot/14-pole PMLM, the two-dimensional finite element analysis (FEA) model and the one-dimensional thermal resistance analysis (TRA) model are erected. The corresponding modeling difficulties and analysis process are shown in detail. Based on the two models, the thermal performances of continuous operation are investigated, including temperature distribution, the optimization of water flow rate, and the influence of water pipe slots number and thermal conductivity of insulation materials. The results show the effect of water-cooling system. The temperature results of these two models are consistent, which are also validated by experimental measurement. Based on the FEA model, the relationship of transient current and the maximum holding time, and the impact of load sustained rate are investigated. Moreover, the thermal characteristics of short-time operation and intermittent periodic operation are studied when the ratio of thrust ripple and average thrust is minimized. Finally, the influence of temperature rise on motor thrust force, efficiency and power factor are investigated.To a double-sided water-cooled12-slot/11-pole PMLM, based on FEA model, the effect of weakening the thrust ripple is investigated by shifting the armature or magnetic pole a certain distance, the motor structure is optimized, and the optimal shifted distance is determined. By comparing with single-sided type, the advantages of shifted type double-sided PMLM are shown. The effectiveness of shifting method is also verified in other two structures (12-slot/13-pole,12-slot/14-pole). Furthermore, for shifted type double-sided PMLMs, the results also indicate that the thrust force performance can be improved when the poles number is larger than the slots number.