Battery Charging Algorithms for Implantable Medical Devices
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Solution Overview
Problem
Implantable medical device systems face overheating issues during battery recharging due to excessive heat generation in external chargers, particularly when both the external and implant batteries require simultaneous charging, which can lead to patient safety risks.
Innovation Solution
The development of charging algorithms that regulate the charging of both external and implant batteries to prevent simultaneous full-power charging, allowing for sequential or alternating charging, or weak simultaneous charging, and incorporating temperature monitoring to adjust charging schemes and reduce heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If simultaneous full-power charging of both external and implant batteries is performed, then charging efficiency is improved, but heat generation increases causing safety risks
Solution Approach 1:
The system implements periodic charging cycles that alternate between charging the external battery and the implant battery. The controller monitors the state of charge of both batteries and switches charging modes periodically, providing full power to one battery while providing reduced or no power to the other, thereby maintaining charging efficiency over time while controlling heat generation at any given moment.
Solution Approach 2:
The charging system dynamically adjusts power distribution between the external and implant batteries based on real-time conditions. The controller modulates the charging power levels, switching between full-power and reduced-power modes, and dynamically selecting which battery receives priority charging based on their respective charge levels and thermal conditions.
2Object-affected harmful factors
If sequential charging of external and implant batteries is performed, then heat generation is reduced, but charging time increases
Solution Approach 1:
The system employs periodic action by implementing alternating charging cycles between the external and implant batteries. Instead of strictly sequential charging, the controller switches between batteries at optimized intervals, providing full power to one while providing reduced power to the other, thereby reducing heat generation while maintaining acceptable overall charging time through parallel operation at different power levels.
3Object-affected harmful factors
If temperature monitoring is implemented to adjust charging schemes, then patient safety is improved, but device complexity increases
Solution Approach 1:
The system implements feedback control by incorporating temperature sensors that continuously monitor the temperature of the external charger and implant device. The controller receives this temperature feedback and automatically adjusts the charging power levels or switches between batteries when temperature thresholds are approached, thereby ensuring patient safety through real-time thermal management without requiring complex manual intervention.
Solution Approach 2:
The charging system performs self-service thermal management by automatically monitoring its own temperature conditions and adjusting its charging operation accordingly. The controller autonomously decides when to reduce power or switch between batteries based on temperature feedback, eliminating the need for external intervention or complex user programming while maintaining safety.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These algorithms ensure safe and efficient battery charging by minimizing heat buildup in the external charger, thereby reducing the risk of overheating and improving patient safety during the recharging process.
Implementation Method 1
an external charger, which produces a magnetic field to ultimately induce a current in a coil in the implant
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
The present invention relates to charging algorithms implementable in an external charger for controlling the charging of both an external battery in the external charger and an implant battery in an implantable medical device. Because full-powered simultaneous charging of both batteries can generate excessive heat in the external charger, the various charging algorithms are designed to ensure that both batteries are ultimately charged, but in a manner considerate of heat generation. In some embodiments, the charging algorithms prevent simultaneous charging of both batteries by arbitrating which battery is given charging precedence at a given point in time. In other embodiments, the charging algorithms allow for simultaneous charging of both batteries, but with at least one of the batteries being only weakly charged at low power levels.; In other embodiments, the temperature generated in the external charger is monitored and used to control the charging algorithm. In these embodiments, if a safe temperature is exceeded, then the charging algorithms change to new temperature-reducing schemes which still allow for both batteries to be ultimately charged.