Present embodiments are directed to measuring and calculating parameters to control and monitor a power transfer in an implanted medical device. The medical device may be implanted in a subject and typically includes an artificial heart or ventricle assist device. The system measures parameters and uses the parameters to calculate a coupling coefficient for coils that transfer power between an external primary and an implanted secondary. The system uses the calculated coupling coefficient to estimate heat flux being generated in the system. Based on the level heat flux detected, the system may issue alerts to warn the subject or control actions to mitigate the effects of the heat flux.
