This paper presents an eigenvalues analysis method for an induction machine model based on phase variables a, b, c. This approach is validated by comparison with ad, q approach and applied to a variable speed pump-turbine unit using a simplified model of the converters. The proposed approach permits the study and analysis of the interaction between mechanical, electric and regulation parts of the system. Index Terms—control systems, numerical simulation, induction motors, AC-DC power converters, pumps, ...