Implanted Stimulator Power Management via Dynamic Voltage Regulation
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Solution Overview
Problem
Existing power management systems for implanted nerve stimulators face inefficiencies due to the need to set power supply voltage to accommodate varying load impedances, leading to unnecessary energy waste and complex hardware requirements.
Innovation Solution
The system automatically adjusts the power-supply voltage within a narrow band just above the minimum acceptable level for the current sink or source in each high-frequency cycle, using a logic controller and solid-state switches to minimize energy consumption and maintain fine time resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the power supply voltage is set to accommodate varying load impedances, then the stimulator can operate with different load conditions, but unnecessary energy waste occurs
Solution Approach 1:
The power supply voltage is dynamically adjusted in real-time to match the actual load requirements. The system continuously monitors the voltage across the current sink/source and modulates the power supply voltage accordingly, ensuring it is never higher than necessary while maintaining adequate headroom for current regulation.
Solution Approach 2:
A feedback mechanism continuously monitors the voltage across the current sink or source and uses this information to regulate the power supply voltage. The system measures the actual voltage drop and adjusts the power supply to maintain optimal voltage levels, preventing energy waste while ensuring proper current sink operation.
2Reliability
If the power supply voltage is increased to ensure adequate headroom for current sink operation, then reliable current regulation is achieved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts the power supply voltage to maintain the minimum necessary headroom for current sink operation. Rather than using a fixed high voltage, the power supply voltage is continuously adapted to provide just enough voltage margin above the current sink voltage, ensuring reliable operation while minimizing power consumption.
Solution Approach 2:
The power supply voltage parameter is continuously changed and optimized based on the actual operating conditions. The system adjusts this parameter to maintain an optimal relationship between power supply voltage and current sink voltage, ensuring adequate headroom for reliable current regulation while minimizing the voltage differential and associated power loss.
3Device complexity
If conventional half-wave rectification with diode is used, then the circuit is simple, but full-wave rectification efficiency is lost
Solution Approach 1:
Instead of using passive diode-based half-wave rectification, the system inverts the approach by using active solid-state switches controlled in both half-cycles of the AC input. This allows full-wave rectification while maintaining circuit simplicity through controlled switching rather than complex passive components.
Solution Approach 2:
The solid-state switches are controlled to automatically conduct during both positive and negative half-cycles of the AC input voltage, enabling the rectifier to serve itself efficiently without external intervention. The control system monitors the input voltage polarity and activates the appropriate switches to achieve full-wave rectification.
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
This approach eliminates unnecessary energy loss and ensures efficient operation by regulating the current-sink or current-source voltage independently of stimulation current and load impedances, while minimizing switch energy consumption.
Implementation Method 1
The alternating voltage VSC of the implanted secondary coil 302 is half-wave rectified
Implementation Method 2
The power supply voltage is generated and adjusted by rectifying the high-frequency voltage of the secondary coil of a transcutaneous magnetic link by closing and opening a solid-state switch at appropriate times
Data Source
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AI summary
Power management methods, systems and circuitry are provided for efficiently energizing implanted stimulators. Efficiency is achieved by automatically adjusting the power- supply voltage of the stimulator channel so that the magnitude of the voltage of the current- sink or current-source providing the stimulation current is regulated within a narrow band just above the minimum acceptable level. Adjustment is done once in every cycle of the external high-frequency power source in order to achieve regulation with a very fine time resolution throughout each stimulation period. The power supply voltage is generated and adjusted by rectifying the high-frequency voltage of the secondary coil of a transcutaneous magnetic link by closing and opening a solid-state switch at appropriate times during positive half cycles for a current-sink, and during negative half-cycles for a current-source. The timing of switch closure and opening is dictated by a logic controller on the basis of two binary signals generated by two separate comparators, one of which comparing the voltage of the secondary coil with the generated power-supply voltage, and the other comparing the current-sink or current-source voltage with a reference voltage.