Heating Control for an Inductive External Charger for an Implantable Medical Device
First Claim
1. A method of controlling an external charger for an implantable medical device, comprising:
- determining at the external charger a first power input to the external charger as it energizes a coil of the external charger to produce a charging field for storing charge in a battery in the implantable medical device;
determining at the external charger a second power dissipated in the energized coil;
determining at the external charger a third power stored in the battery of the implantable medical device; and
controlling the charging field using at least the first, second, and third powers.
1 Assignment
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Accused Products
Abstract
The disclosed technique for charging a battery in an implantable medical device using an external charger indirectly determines the total power dissipated as heat in the IPG (P_IPG) by accounting for the various powers in the external charger/IPG system which are either known or can be measured, such as the input power provided to the amplifier that drives the coil in the external charger (Psys), the power stored in the IPG'"'"'s battery (Pstored), and the power dissipated in the external charger'"'"'s charging coil as heat (P_EC) (which is measured). Determining P_IPG at the external charger in this manner allows the heat flux from the IPG to be calculated (F_IPG), and compared to a safe heat flux limit (F_IPG′) to allow for adjustment to the power of the magnetic charging field in a closed loop fashion.
17 Citations
33 Claims
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1. A method of controlling an external charger for an implantable medical device, comprising:
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determining at the external charger a first power input to the external charger as it energizes a coil of the external charger to produce a charging field for storing charge in a battery in the implantable medical device; determining at the external charger a second power dissipated in the energized coil; determining at the external charger a third power stored in the battery of the implantable medical device; and controlling the charging field using at least the first, second, and third powers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An external charger for an implantable medical device, comprising:
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a driver circuit configured to provide a charge current to a coil to produce a magnetic charging field to store charge in a battery in the implantable medical device; and a control circuit configured to control the driver circuit in accordance with an algorithm configured to determine a power dissipated in the implantable medical device, wherein the algorithm determines the power dissipated in the implantable medical device by subtracting a power stored in the battery and power dissipated in the coil from a power input to the driver circuit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification