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