The rate of {HEAD ~ change} of {TAIL ~ the flux} in the primary winding induces a voltage in a sensing winding, which voltage is integrated and used to control the on time of the switching device so as to control the flux in the main coil 
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The rate of { HEAD ~ change } of { TAIL ~ the flux } in the primary winding induces a voltage in a sensing winding , which voltage is integrated and used to control the on time of the switching device so as to control the flux in the main coil
OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH