External power source, system and method for predicting heat loss of implantable medical device during inductive recharging by external primary coil

An external power source for inductively charging of an implantable medical device in a patient, said implantable medical device having a rechargeable power source having a voltage and a secondary coil operatively coupled to said rechargeable power source, comprising:

• a primary coil;
• electronic circuitry driving said primary coil;
• and
• control circuitry, operatively coupled to said electronic circuitry, configured to control energy absorbed in said patient during inductive charging of said rechargeable power source by:
• determining a total applied power by said external power source by measuring current applied by said external power source during said charging and an applied voltage of said external power source;
• determining power lost in said electronic circuitry;
• determining power lost in said primary coil by determining current in said primary coil during said recharging in view of a resistance of said primary coil;
• determining power applied to said rechargeable power source by measuring said voltage of said rechargeable power and current applied to said rechargeable power source during said inductive charging;
• calculating said energy absorbed in said body by subtracting said power lost in said electronic circuitry, said power lost in said primary coil and said power applied to said rechargeable power source from said total applied power;
• and
• adjusting said total applied power by said external power source as a function of said energy absorbed in said patient.

A system for controlling energy absorbed in a patient during inductive charging, comprising;

• an implantable medical device, comprising;
• therapeutic componentry delivering a therapeutic output to said patient;
• a rechargeable power source operatively coupled to said therapeutic componentry;
• and
• a secondary coil operatively coupled to said rechargeable power source;
• and
• an external power source, comprising:
• a primary coil;
• electronic circuitry driving said primary coil;
• and
• control circuitry, operatively coupled to said electronic circuitry, configured to control energy absorbed in said patient during inductive charging of said rechargeable power source by:
• determining a total applied power by said external power source by measuring current applied by said external power source during said charging and an applied voltage of said external power source;
• determining power lost in said electronic circuitry;
• determining power lost in said primary coil by determining current in said primary coil during said recharging in view of a resistance of said primary coil;
• determining power applied to said rechargeable power source by measuring said voltage of said rechargeable power source and current applied to said rechargeable power source during said inductive charging;
• calculating said energy absorbed in said body by subtracting said power lost in said electronic circuitry, said power lost in said primary coil and said power applied to said rechargeable power source from said total applied power;
• and
• adjusting said total applied power by said external power source as a function of said energy absorbed in said patient.

A device implemented method of determining energy absorbed in a body during inductive charging of an implantable medical device having a rechargeable power source having a voltage and a secondary coil operatively coupled to said rechargeable power source by an external power source having electronic circuitry driving a primary coil, comprising the steps of:

• determining a total applied power by said external power source by measuring current applied by said external power source during said charging and an applied voltage of said external power source;
• determining power lost in said electronic circuitry;
• determining power lost in said primary coil by determining current in said primary coil during said recharging in view of a resistance of said primary coil;
• determining power applied to said rechargeable power source by measuring said voltage of said rechargeable power source and current applied to said rechargeable power source during said inductive charging;
• and
• calculating, via circuitry, said energy absorbed in said body by subtracting said power lost in said electronic circuitry, said power lost in said primary coil and said power applied to said rechargeable power source from said total applied power.

A method for adjusting an amount of energy dissipated in a patient during inductive charging of an implantable medical device having a rechargeable power source having a voltage and a secondary coil operatively coupled to said rechargeable power source by an external power source having electronic circuitry driving a primary coil, comprising the steps of:

• determining a total applied power by said external power source by measuring current applied by said external power source during said charging and an applied voltage of said external power source;
• determining power lost in said electronic circuitry;
• determining power lost in said primary coil by determining current in said primary coil during said recharging in view of a resistance of said primary coil;
• determining power applied to said rechargeable power source by measuring said voltage of said rechargeable power and current applied to said rechargeable power source during said inductive charging;
• calculating said energy absorbed in said patient by subtracting said power lost in said electronic circuitry, said power lost in said primary coil and said power applied to said rechargeable power source from said total applied power;
• and
• adjusting said total applied power by said external power source as a function of said energy absorbed in said patient.