The performance of synchronous reluctance motor (SynRM) degrades due to chaos when its systemic parameters fall into a certain area.To control the undesirable chaos in SynRM,a passive control law is presented in this paper,which transforms the chaotic SynRM into an equivalent passive system.It is proved that the equivalent system can be asymptotically stabilized at the set equilibrium point,namely,chaos in SynRM can be controlled.Moreover,in order to eliminate the influence of undeterministic parameters,an adaptive law is introduced into the designed controller.Computer simulation results show that the proposed controller is very effective and robust against the uncertainties in systemic parameters.The present study may help to maintain the secure operation of industrial servo drive system.