Simplified design model for fast analysis of large synchronous generators with magnetic saturation

This paper presents simplified alternator design tools which could evaluate the performances of a large machine in function of its geometrical dimensions and winding parameters. This method is well adapted for fast comparisons of different alternator structures and a first optimization of the alternator characteristics. It is based on two kinds of analytical models for the estimation of the equivalent electrical circuit parameters. These models are using a small non-linear reluctance network of one pole domain and a solution of the linear Maxwell equations in the air-gap of a simplified structure of entire machine to calculate inductances and no-load flux by taking account winding characteristics. We simulate two classical machine tests (stator short-circuit and no-load operation) for different rotor excitation currents for the identification of a saturated circuit equivalent parameters. We present two examples using the specifications and the characteristics of existing hydraulic alternators. We make some comparisons with FE method and validate the performances of the original machines as found with the analytical saturated model with those defined by the machine specifications.