Wireless Charger Frequency Tuning for Implantable Pulse Generator
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Solution Overview
Problem
Current wireless chargers for implantable pulse generators (IPGs) in spinal cord stimulation systems face inefficiencies, improper alignment issues, and lack of automatic termination of charging, making them suboptimal for effective and safe battery charging.
Innovation Solution
A wireless charger that automatically tunes an optimum frequency for inductive charging by detecting reflected impedance, optimizing the charging frequency to enhance efficiency and ensure proper alignment through feedback mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a fixed frequency charging signal is used, then the charging process is simple, but the charging efficiency is low due to inability to adapt to varying coupling conditions
Solution Approach 1:
The charging signal frequency is changed from a fixed value to a dynamically adjustable parameter. The system automatically tunes the frequency by sweeping through a range of frequencies and selecting the one that maximizes power transfer, thereby adapting to varying coupling conditions between the charging coil and receiving coil while maintaining reasonable system complexity through automated control.
Solution Approach 2:
The frequency parameter of the charging signal is varied to optimize charging efficiency. The system implements frequency sweeping across a predetermined range and identifies the optimal frequency based on reflected impedance measurements, allowing the charging process to adapt to different coupling conditions without requiring complex manual adjustment.
2Productivity
If manual charger alignment is used, then the charging system is simple, but improper alignment occurs leading to reduced power transfer efficiency
Solution Approach 1:
The system measures reflected impedance during the charging process and uses this feedback information to determine optimal alignment. By monitoring changes in reflected impedance as the charger is moved or adjusted, the system can identify when maximum power transfer is achieved and provide feedback to guide proper alignment, eliminating the need for complex manual positioning procedures.
Solution Approach 2:
The charging system automatically detects and adapts to optimal alignment conditions through reflected impedance measurement. The controller autonomously determines when proper alignment is achieved and adjusts charging parameters accordingly, freeing the user from the burden of precise manual alignment while ensuring maximum power transfer efficiency.
3Reliability
If continuous charging is performed, then the battery is fully charged, but overcharging occurs causing safety issues and energy waste
Solution Approach 1:
The system continuously monitors charging parameters including reflected impedance and power transfer efficiency to detect when the battery reaches full charge. When overcharging conditions are detected or when impedance changes indicate full charge, the system automatically terminates or adjusts the charging process, preventing energy waste and ensuring battery safety while maintaining complete charging.
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 solution provides a more efficient and reliable charging process, ensuring optimal power transfer and preventing overcharging, thus improving the functionality and safety of the spinal cord stimulation system.
Implementation Method 1
The charging coil in the charger is wirelessly coupled to a receiving coil of the IPG to charge the rechargeable battery
Implementation Method 2
An optimization circuit detects a reflected impedance of the charging coil through a reflected impedance sensor
Data Source
AI summary
A wireless charger for automatically tuning an optimum frequency to inductively charge a rechargeable battery of an implantable pulse generator (IPG) that generates spinal cord stimulation signals for a human body is provided. The charging coil in the charger is wirelessly coupled to a receiving coil of the IPG to charge the rechargeable battery. An optimization circuit detects a reflected impedance of the charging coil through a reflected impedance sensor, and select an optimum frequency of a charging signal supplied to the charging coil based on the detected reflected impedances of a plurality of charging frequencies in a selected frequency range. Advantageously, the optimum charging frequency provides a more efficient way to charge the IPG's rechargeable battery.