The magnetic properties of the rotor and {HEAD ~ cores} are selected to insure that the pole strength in the teeth will be retained during the changes in {TAIL ~ electromagnet current} 
The magnetic properties of the rotor and { HEAD ~ cores } are selected to insure that the pole strength in the teeth will be retained during the changes in { TAIL ~ electromagnet current }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL