Transient analysis of induction machine deep bar current displacement through bar layer model

The aim of this contribution is to advance in the description of the bar current displacement effect in induction machines with deep rotor bars. The model proposes a transient bar layer model that is based on the former steady state studies (the multiple bar layer model) to provide a state space model of the bar layer currents that can be integrated in standard transient performance models of the induction machine. The transient bar layer model results are compared with the analytical results for steady state performance showing very good agreement. The model results are compared also with a previous proposal based on uncoupled time-finite element method (FEM) calculations showing a better description of the transient bar current displacement effect that should be considered in the design of high-performance torque control systems for converter-fed induction machines. The transient bar layer model has been validated also against FEM calculation including the eddy current effect equivalent to the bar current displacement under transient conditions equivalent to those typical of converter-fed operation. The proposed model is quite time efficient compared to such coupled time-FEM models able to represent the bar current displacement and, thus, it is very well suited to the effective design and tuning of induction machine control systems.