Thermal error is a crucial factor affecting the accuracy of linear motor feed drive systems (LMFDS). To improve the prediction accuracy, a thermal error model for LMFDS considering the multi-field coupling of electromagnetic-thermal-flow (EM-TF) is proposed. Firstly, the thermal error mechanism is analyzed and the temperature control equation of LMFDS is deduced under multi-field coupling of electromagnetic, thermal, and flow fields. Then, aiming at the difficulty to solve the control equation directly, an indirect solution method is proposed. According to the simplification conditions of the actual process, the control equation is divided into three stages and then recoupled together. Finally, a prediction model for LMFDS thermal error is established based on the temperature equation and thermal expansion theory. Compared with traditional models, the proposed model has a good physical meaning and prediction accuracy. In addition, experiments have proven that the model can automatically adjust the linear and nonlinear intervals, fully reflecting the entire changing process of thermal error in LMFDS.
