Power Source Switching Matrix for Multi-Battery Wireless Charging
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Solution Overview
Problem
Conventional control circuits in wireless devices that employ energy harvesters limit the size and type of batteries that can be used due to limitations in managing current flow and charging procedures, particularly for lithium-ion batteries, which require specific charging modes to avoid over-charging.
Innovation Solution
A wireless device with a power management circuit that includes a controller and switcher matrix, allowing dynamic selection of power sources (energy harvester, USB power, or battery) based on voltage levels and connections, and storing configuration data for specific charging procedures, including constant current and constant voltage modes for lithium-ion batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional control circuits are used to manage energy harvester charging, then the circuit structure is simple, but the battery size and type are limited due to inability to control current flow and prevent over-charging
Solution Approach 1:
The power management circuit dynamically adjusts its operating mode based on real-time conditions. The controller monitors battery charge levels and automatically switches between different charging modes (constant current, constant voltage, or energy harvester charging) to accommodate various battery types and sizes while maintaining safe charging operations
Solution Approach 2:
The system changes charging parameters (current limits, voltage thresholds, charging modes) based on detected battery characteristics and charge states. This allows the same circuit to safely charge different battery types by adapting the charging profile rather than requiring different hardware circuits for each battery type
2Productivity
If energy harvester is used to charge the battery, then battery charging is achieved, but the charging time is several hours due to threshold level requirements
Solution Approach 1:
The system maintains continuous charging operation by eliminating unnecessary idle periods. The controller keeps the energy harvester actively charging the battery throughout the entire charging process rather than waiting for threshold levels, ensuring uninterrupted energy transfer from the harvester to the battery
Solution Approach 2:
The system performs preliminary charging actions by allowing the energy harvester to charge the battery from the beginning without waiting for capacitor threshold levels to be reached first. This preliminary charging action eliminates the initial delay period and starts the battery charging process immediately
3Ease of operation
If capacitor threshold level must be reached before battery charging, then charging control is simplified, but the battery charging is delayed by several hours
Solution Approach 1:
The system extracts and removes the unnecessary delay caused by capacitor threshold requirements. The controller is configured to bypass the traditional sequential charging process (capacitor first, then battery) and directly initiate battery charging from the energy harvester, eliminating the time-consuming intermediate step
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 the use of various battery types and sizes by dynamically managing charging configurations, ensuring efficient and safe charging of lithium-ion batteries without over-charging, thereby extending battery life and improving power management.
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
a switcher matrix configured to power the load at system startup using the selected power source
Implementation Method 3
a second port selectively connected to a battery
Data Source
AI summary
A wireless device includes an energy harvester to convert harvested energy into a harvested voltage, a first port selectively connected to an external USB power source, a second port selectively connected to a battery, a load including a plurality of circuits, and a power management circuit coupled to the energy harvester, the first and second ports, and the load. The power management circuit includes a controller configured to select one of the energy harvester, the USB power source, or the battery as a power source at system startup based on one or more of an amount of the harvested voltage, a presence of a connection with the USB power source, a presence of a connection with the battery, or an amount of charge or voltage stored by the battery. The power management circuit also includes a switcher matrix to power the load at system startup using the selected power source.