Power Management Circuit for Multi-Source Battery Charging
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Solution Overview
Problem
Conventional control circuits for wireless devices with energy harvesters limit the size and type of batteries that can be used, often requiring batteries to be selected based on worst-case current flow to avoid over-charging, excluding certain battery sizes and types, and do not support charging procedures for lithium-ion batteries effectively.
Innovation Solution
A power management circuit that includes a controller and a switcher matrix to dynamically select power configurations based on the presence of USB power sources, batteries, and harvested energy levels, using configuration data to manage charging and power delivery operations, supporting various battery types including lithium-ion batteries through specific charging procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control circuits are used to manage energy harvesting and battery charging, then battery over-charging is avoided through worst-case current flow limitations, but the size and type of batteries are restricted and lithium-ion battery charging procedures are not supported
Solution Approach 1:
The control circuit dynamically adjusts current flow limits based on real-time battery parameters (capacity, type, charge level) rather than using fixed worst-case limitations. The system monitors battery status and adapts charging parameters accordingly, enabling support for various battery types including lithium-ion while maintaining over-charging protection
Solution Approach 2:
The system changes operating parameters (current limits, charging rates) based on detected battery characteristics. By identifying battery type and capacity, the control circuit modifies charging parameters to match optimal charging procedures for each battery type, thereby supporting diverse battery sizes and types without compromising safety
2Reliability
If worst-case current flow limits are applied to prevent battery over-charging, then battery safety is ensured, but the battery capacity and size are constrained
Solution Approach 1:
The control circuit implements dynamic current limiting that adjusts based on real-time battery charge level and capacity. Instead of applying fixed worst-case limits throughout charging, the system modulates current flow according to actual battery needs, enabling safer use of higher-capacity batteries while preventing over-charging
Solution Approach 2:
The system continuously monitors battery charge level, voltage, and current, using this feedback to adjust charging parameters in real-time. This closed-loop control enables the system to safely charge larger capacity batteries by adapting current limits based on actual battery status rather than relying on conservative worst-case assumptions
3Device complexity
If fixed charging protocols are used in control circuits, then charging management is simplified, but support for different battery types including lithium-ion is limited
Solution Approach 1:
The control circuit is designed with multi-functionality to support multiple battery types including lithium-ion, alkaline, and nickel-based batteries. By incorporating battery identification capabilities and multiple charging protocol support, the single control circuit can adapt to different battery types without requiring separate dedicated circuits for each battery chemistry
Solution Approach 2:
The charging protocol dynamically switches based on detected battery type. The control circuit identifies the battery chemistry and automatically selects the appropriate charging algorithm, transitioning between different charging modes (constant current, constant voltage, tapering) according to the specific requirements of each battery type
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
Enables efficient charging of lithium-ion batteries without over-charging, allowing for a wider range of battery sizes and types to be used, extending battery life and reducing power consumption in wireless devices.
Implementation Method 1
an energy harvester that can capture energy (such as radio-frequency (RF) energy, solar energy, mechanical energy, piezoelectric energy, or thermoelectric energy, among other examples) and convert the captured energy into a voltage
Implementation Method 2
the harvested energy is collected from solar energy present in the surrounding environment
Data Source
AI summary
A method for powering a wireless device includes determining a presence or absence of a USB power source connected to the wireless device, determining a presence or absence of a battery connected to the wireless device, obtaining a level of energy harvested from a surrounding environment of the wireless device, and powering a load of the wireless device using one of the USB power source, the battery, or the harvested energy based on the presence or absence of the USB power source, the presence or absence of the battery, and the harvested energy level.