Excitation current calculation of a brushless synchronous generator under different speed and load

The excitation current calculation is significant for BLSG design and efficiency analysis. While, the varying work condition bring big difficult to analyze the excitation characteristic of the BLSG. In this paper, a steady state excitation current calculation method for BLSG which can reflect the speed and load change is presented. Firstly, the transform equations from three phase coordinated to d-q axial is given. Then, the excitation current calculation model is deduced based on the steady state model of BLSG. In which, the OCC is adopted to calculate the saturation of BLSG reaction reactance under rated speed. Then, the calculation model is extended to common speed through conversion. Finally, the calculation simulation of excitation current under different speed and load is conducted. The result shows that the excitation current and saturation degree decrease with the speed increase and increase with the rising load.