Iron Loss Analysis and Efficiency Calculation of Double Stator HTS Machine With Stationary Seal

This paper mainly analyzes the iron loss of a double stator high-temperature superconducting (HTS) machine with stationary seal and calculates its efficiency. Firstly, according to the field-modulation theory, the air-gap flux density harmonic components of the excitation magnetic field and armature-reaction magnetic field are derived. Secondly, the air-gap flux density harmonic components corresponding to the flux density harmonic components of iron core are derived, and the main iron core flux density harmonic components are confirmed and verified by finite element analysis (FEA). When using the semi-FEA method to calculate the iron loss, according to the analysis results of main core flux density harmonic components, the appropriate step-interval of the FEA is selected. In addition, according to the characteristics of the iron core flux density, this paper proposes an alternative method of iron core flux density, which greatly shortens the calculation time of semi-FEA method of iron loss calculation. Then, iron loss model with variable coefficients is used to calculate the iron loss of the machine, and the calculation results are compared with those of the FEA iron loss calculation method. Finally, other losses and efficiency of the machine are calculated.