Fast computation of torque-speed characteristics of induction machines

In this paper, to save computation time, an adaptive speed-torque estimation method is proposed. Firstly, the basic FEM formulations are reviewed. To calculate the process of speed-torque characteristics, the computation is accomplished within one transient FEM process while at each time, and the torque is calculated from its last stable value. To reduce the transient process computation time, some methods are introduced. Time step size and nonlinear iteration tolerance are adjusted gradually and smoothly from a large value to a regular value until steady-state solution is reached, resulting in a significantly reduction in the total computing time. After collecting the discrete data and the continuous torque-speed characteristics of induction motors are estimated. An 1.1kW, 380V three phase induction motor is used as a numerical example to verify the effectiveness of proposed method.