End effects in unlaminated-rotor induction machines

A new theory is presented for end effects in unlaminated-rotor induction machines with or without conducting rotor endplates, and a design criterion for the choice of endplate thickness is deduced. The theory is extended to cover end regions of arbitrary form. Experimental results are given for 6–1500 W motors that substantiate the analysis, and show that end effects may be considerable even in rotors with conducting endplates.