Battery Charging Apparatus with Temperature-Compensated Voltage Thresholds
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Solution Overview
Problem
Lithium iron phosphate (LFP) batteries experience rapid power loss at low temperatures, and existing charging methods, such as CC and CC-CV algorithms, require high power electrical components that increase costs and reduce lifespan, while also risking incomplete charging within the permissible maximum charging time, especially in emergency systems.
Innovation Solution
A method that dynamically adjusts the charging current based on cell voltage and temperature, allowing for two phases of charging: a constant current phase at lower voltages and a reduced current phase at higher voltages, with the second threshold value set as a function of temperature, enabling efficient charging and extending the charging process at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If high charging current is supplied to charge LFP batteries quickly, then charging time is reduced, but electrical components must be designed for high power which increases cost and reduces lifespan
Solution Approach 1:
The patent applies dynamics by making the charging current adaptive rather than constant. The control unit dynamically adjusts the charging current based on real-time temperature measurements from the battery. At low temperatures, the charging current is limited to prevent thermal damage, while at higher temperatures, the current can be increased to accelerate charging. This dynamic adjustment resolves the contradiction by allowing high current charging when safe and reducing current only when temperature constraints exist.
Solution Approach 2:
The patent changes the parameter of charging current based on temperature conditions. By monitoring battery temperature and adjusting the charging current parameter accordingly, the system optimizes charging speed while protecting components. The control unit implements temperature-dependent current limiting, which allows maximum charging power when the battery can accept it, and reduces power only when thermal constraints require it, thus resolving the trade-off between charging speed and component stress.
2Duration of action of stationary object
If charging current is reduced to lower power demand on components, then component lifespan is extended, but charging time exceeds the permissible maximum charging time
Solution Approach 1:
The system uses dynamic current adjustment based on temperature feedback. Rather than using a fixed reduced current, the control unit continuously monitors battery temperature and adjusts the charging current in real-time. This allows the system to maintain high current when the battery temperature permits, extending component lifespan only when necessary, while achieving complete charging within the permissible time frame by utilizing higher currents when thermal conditions allow.
Solution Approach 2:
The patent implements feedback control by continuously monitoring battery temperature and using this information to adjust the charging current. The control unit receives temperature data from sensors and dynamically modifies the charging parameters accordingly. This closed-loop feedback system ensures that the charging process adapts to real-time thermal conditions, optimizing both component lifespan and charging time by preventing unnecessary current reduction.
3Productivity
If fixed high power components are used to ensure complete charging within maximum time, then charging time requirement is met, but device cost increases and lifespan is reduced
Solution Approach 1:
The patent replaces fixed high-power component design with a dynamic control approach. Instead of sizing components for maximum continuous high-power operation, the system uses temperature-based control to dynamically adjust the charging current. This allows the use of lower-rated, more cost-effective components that only operate at high power when thermal conditions permit, rather than requiring oversized components designed for worst-case continuous operation.
Solution Approach 2:
The system changes the operating parameters of the charging device based on temperature conditions. By implementing temperature-dependent current control, the patent allows components to operate at lower average power levels, reducing thermal stress and extending lifespan. The parameters are adjusted in real-time to meet charging speed requirements when possible, while reducing power demand when temperature constraints exist, thereby eliminating the need for expensive high-power-rated components.
4Productivity
If temperature-dependent threshold adjustment is implemented, then charging efficiency is optimized for low temperatures, but control complexity increases
Solution Approach 1:
The patent uses feedback control where the control unit monitors battery temperature and automatically adjusts the charging current threshold accordingly. This feedback mechanism optimizes charging efficiency across different temperature ranges without requiring complex manual intervention or sophisticated control algorithms. The control unit simply compares the measured temperature against predefined thresholds and adjusts the charging parameters accordingly, providing an elegant balance between optimization and simplicity.
Solution Approach 2:
The system implements parameter changes by adjusting the charging current threshold based on temperature measurements. The control unit modifies operational parameters (charging current limits) according to the measured temperature, allowing optimized charging efficiency at low temperatures while maintaining safe operation at high temperatures. This parameter adaptation is achieved through relatively simple temperature-based control logic rather than complex algorithms, maintaining ease of implementation.
Data Source
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AI summary
A method for controlling a battery charging device for charging a lithium-based energy storage device with at least one cell comprises the following steps: determining the cell voltage and supplying a constant charging current to the cell if the determined cell voltage is less than a first threshold, and monitoring the cell voltage. If the monitored cell voltage is greater than a second threshold, a charging current less than the constant charging current is supplied to the cell, and the cell voltage is monitored. The method determines the temperature of the energy storage device and sets the second threshold based on the determined temperature.