Simulation of Induction Motor Using State Variables

The paper presents the simulation of the induction motor both in transient behavior and in steady-state. The transient behavior analysis is based on the state variable approach, the equations being formulated in symbolic normal form with respect to the orthogonal axes d, q, 0. For the integration of the state equations, the ODE45 routine from Matlab is used. For the steady-state the one phase equivalent circuit of the induction motor is used and the modified nodal equations in full-symbolic form are formulated. The circuit contains a time-variable resistor depending of the electrical slip. The paper is focused on the electrical and mechanical quantities that are obtained from the motor model. In order to formulate the modified nodal equations in full-symbolic form we use an original computing program called SYMNAP - SYmbolic Modified Nodal Analysis Program. The results obtained by simulation are very important in the induction motor design and in the parameters' identification of this kind of motors.