Patent ID: 11896838
Assignee: MEDTRONIC, INC.
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC A  H | IPC A  H

Claim 0:
1. A method for controlling charging of a rechargeable power source of an implantable medical device (IMD) in a patient, the method comprising:
determining, by processing circuitry of an external charging device, a power being delivered to a primary coil of the external charging device for recharging the IMD, wherein the external charging device comprises the primary coil and a ferrite material adjacent to the primary coil and spanning an aperture defined by the primary coil;
determining, by the processing circuitry, an estimated power delivered to the rechargeable power source during charging of the IMD;
calculating, by the processing circuitry, an estimated heat generated by the primary coil based on a resistance of the primary coil, wherein the resistance of the primary coil is determined as a function of at least one of a recharge frequency, a temperature of the primary coil, and a current supplied to the primary coil, the resistance of the primary coil determined as a variable so as to account for the presence of the ferrite material in the external charging device;
calculating, by the processing circuitry, an estimated heat generated by the IMD by subtracting the estimated heat generated by the primary coil and the estimated power delivered stored by the rechargeable power source from the power being delivered to a primary coil; and
controlling, by the processing circuitry and based on the heat generated by the IMD, the power being delivered by the primary coil of the external charging device,
wherein the estimated heat generated by the primary coil is determined at least in part by empirically derived values for a given recharge frequency based on a regression analysis fitting a curve to a measured coil resistance for the primary coil as a function of frequency for a given temperature of the primary coil.