Battery Charging Voltage Control for Longer Lithium-Ion UPS Life
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Solution Overview
Problem
Lithium-ion batteries in UPS systems face challenges in extending their life due to sensitivity to operating conditions like charging voltage and temperature, leading to increased warranty costs and reduced back-up time, especially when operated at varying loads below full capacity.
Innovation Solution
A battery-charging system that dynamically adjusts the charging voltage based on load conditions using a load-detection circuit and microcontroller, switching between nominal and high voltages to optimize battery life while maintaining performance specifications, and includes user-controlled modes for voltage adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the battery is charged to high voltage continuously, then the back-up time and performance are improved, but the battery life is reduced due to increased sensitivity to operating conditions
Solution Approach 1:
The patent implements dynamic voltage adjustment where the charging voltage switches between nominal and high voltage levels based on detected load conditions. The controller monitors load magnitude and adjusts the charging voltage accordingly, making the system adaptive rather than static. This resolves the contradiction by providing high voltage only when needed for performance while using nominal voltage during low loads to preserve battery life.
Solution Approach 2:
The patent changes the operating parameter (charging voltage) based on load conditions. When load is detected above a threshold, the system switches to high voltage charging to ensure adequate back-up time. When load is below the threshold, it switches to nominal voltage to reduce stress on the battery and extend its life. This parameter adjustment strategy resolves the contradiction between performance and longevity.
2Use of energy by moving object
If the battery is operated at varying loads below full capacity, then the energy efficiency is improved, but the battery life is reduced due to increased sensitivity to operating conditions
Solution Approach 1:
The patent employs a feedback mechanism where the controller continuously monitors load conditions and adjusts the charging voltage in response. The load detection circuit provides real-time information about the operating conditions, and the controller uses this feedback to switch between nominal and high voltage modes. This closed-loop control resolves the contradiction by optimizing the operating point based on actual conditions rather than operating at fixed parameters.
3Power
If the charging voltage is increased to extend back-up time, then the power delivery capability is improved, but the warranty costs increase due to reduced battery life
Solution Approach 1:
The system dynamically adjusts charging voltage based on actual load requirements rather than maintaining a fixed high voltage. During low-load conditions, the system uses nominal voltage to reduce battery stress and extend life, thereby lowering warranty costs. During high-load conditions, it switches to high voltage to ensure adequate power delivery capability. This dynamic approach resolves the contradiction between power capability and reliability.
Data Source
AI summary
A battery-charging system configured to charge a battery of a device to a nominal voltage includes a load-detection circuit, memory storing controller-executable instructions, and a controller configured to execute the instructions, which cause the controller to detect a load coupled to the battery above a first threshold load using the load-detection circuit, and control the battery-charging circuit to charge the battery to a high voltage in response to detecting the load above the first threshold load, wherein the high voltage is above the nominal voltage. The controller can be configured to execute other instructions, such as outputting a notification that the battery is being charged to a high voltage and/or controlling the battery-charging circuit to discharge the battery in response to detecting a reduced load or a user command.