Dynamic Charging Current Control for IMD Battery Life Extension
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Solution Overview
Problem
Implantable medical device batteries experience capacity reduction over time due to various parameters such as charging history, usage, and age, leading to reduced functionality and the need for premature replacement.
Innovation Solution
A battery management system that adjusts the charging current based on historical parameters and battery capacity, using an algorithm to control the charging circuitry and adjust the resistance in the trickle charging path to extend battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the battery charging current is increased to quickly recharge the battery, then the charging time is reduced, but the battery capacity loss accelerates and battery life is shortened
Solution Approach 1:
The charging current is made dynamic rather than fixed. The system continuously monitors battery parameters (voltage, temperature, charge state) and adjusts the charging current in real-time based on the battery's actual condition. This allows the charging current to be high when the battery can accept it (reducing charging time) and low when the battery is near full or under stress (preserving battery life).
Solution Approach 2:
The system implements feedback control by monitoring battery parameters during charging and using this information to adjust the charging current. The controller receives feedback on battery voltage, temperature, and charge state, then modifies the charging current accordingly to optimize both charging speed and battery longevity.
2Reliability
If the charging current is continuously high to maintain device functionality, then the device operates reliably, but the battery capacity degrades faster requiring premature replacement
Solution Approach 1:
The system applies partial charging actions when full charging is not necessary. Instead of continuously charging at maximum current to ensure functionality, the system charges the battery to sufficient levels for device operation and then reduces or stops charging, avoiding excessive charge cycles that degrade battery capacity over time.
Solution Approach 2:
The system changes charging parameters (current magnitude, charging rate) based on battery state and device requirements. Rather than maintaining a constant high charging current, the system adjusts parameters dynamically - using higher currents when needed for quick top-ups and lower currents or no charging when the battery is sufficiently charged, thereby extending battery operational life while maintaining device functionality.
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
The system effectively slows down battery capacity loss, extending the life of the implantable medical device and reducing the need for surgical replacement by optimizing charging currents over time.
Implementation Method 1
a charging coil (44) for wirelessly receiving a magnetic charging field from an external charger (90) for recharging the battery (36)
Data Source
AI summary
An algorithm programmed into the control circuitry of a rechargeable-battery Implantable Medical Device (IMD) is disclosed that can adjust the charging current (Ibat) provided to the rechargeable battery over time (e.g., the life of the IMD) in accordance with one or more of the parameters having an effect on rechargeable battery capacity, such as number of charging cycles, charging current, discharge depth, load current, and battery calendar age. The algorithm consults such parameters as stored over the history of the operation of the IMD in a parameter log, and in conjunction with a battery capacity database reflective of the effect of these parameters on battery capacity, estimates a change in the capacity of the battery, and adjust the charging current in one or both of trickle and active charging paths to slow the loss of battery capacity and extend the life of the IMD.