Kron´s reduction method applied to the time stepping finite element analysis of induction machines

The behavior of large induction motors during transient as well as steady state running conditions is of significant interest to the power industry. A variety of analytical predictive tools are employed to aid the design and predict their operation under transient and steady state conditions. This paper presents a strategy to reduce the required running time in order to make a parametric study of induction machines such as the assessment of different design options feasible. This is accomplished by reducing the number of finite element equations that must be solved while maintaining the same level of accuracy of solutions. This method is based on Kron´s network reduction work for linear systems and has successfully been applied to large lumped parameter model of transformers. This paper illustrates the reduction method by comparing the flux density in the air gap for a complete FEM model of an induction machine to that of the reduced model. The results are essentially identical with a reduction in computational time of approximately 71%