A Thrust Ripple Suppression Method for Long-Primary Double-Sided Linear Induction Motors Based on Harmonic Current Injection

For the long-primary double-sided linear induction motor (LP-DSLIM) excited by the symmetrical current, there is a double slip frequency ripple in the thrust due to the dynamic longitudinal end effect. The expression of thrust ripple fluctuation caused by the dynamic longitudinal end effect is deduced first. Second, the method of suppressing the injected harmonic current is adopted, the expression of each part of thrust after injection is deduced, and its characteristics are analyzed, from which the feasibility of this method to reduce the thrust ripple is illustrated. Finally, the finite-element simulation and experiment results indicate that the thrust ripple is significantly reduced after the injection of the harmonic current.