Research on Tractive Characteristics of the Single Linear Induction Motor

The SLIM has been widely applied in transportation for its simple-firm structure and its directly forward electromagnetic thrust. The motor has transverse and longitudinal end-effects because of its discontinuous magnetic circuit. There are eddy currents, which become greater as motor speed increases, occurring in both entrance and exit of its secondary sheet. End effects and eddy currents bring ill impact to air gap magnetic flux, which reduce its available magnetic flux and pull coefficient. This paper works out the d-q axis equivalent circuits of SLIM considering end effects. The changes of mutual inductance and resistance in d-axis indicate both the second longitudinal end effect and the eddy current influences. Then the article establishes SLIM math equations connected with the rotor-flux oriented (RFO) vector control theory. This paper brings forward u_ds, u_qs, i_qs online decouple compensation basing on the rotor magnetic flux, speed, current regulators, which adjust and accommodate tractive force, d-q axis voltages, d-q magnetic fluxes, d-axis mutual inductance. The simulation and experimental results indicate that this method is reasonable, which provides theory guidance to the SLIM application analysis and achieves some active effects.