Battery Charging Current Pulse Control via Clamp Voltage Adjustment
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Solution Overview
Problem
Existing battery charging methods either reduce battery lifespan or increase charge time, as they do not efficiently manage charge current based on the state of charge (SoC) and terminal voltage, leading to potential harm to the battery's cycle life.
Innovation Solution
An optimized charging algorithm that provides charge current pulses in multiple steps, stepping down the high time current and increasing the clamp voltage as the terminal voltage rises, transitioning through pulsing, pulse-only, and constant voltage profiles to maximize charging efficiency and minimize battery stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If constant current charging is applied to a battery, then charging speed is improved, but battery lifespan deteriorates due to excessive stress on the battery
Solution Approach 1:
The charging current is made dynamic rather than constant. The system adjusts the charging current in multiple steps based on the battery's terminal voltage and state of charge. High current pulses are applied when the battery voltage is low, then the current is stepped down as voltage increases, resolving the contradiction between fast charging and battery stress
Solution Approach 2:
The charging parameters (current magnitude and pulse duration) are changed based on the battery's state. The system monitors terminal voltage and adjusts charging current accordingly, transitioning from high current at low voltage to lower current as voltage approaches maximum, thereby maintaining fast charging while reducing battery stress
2Reliability
If charging current is reduced to extend battery life, then battery lifespan is improved, but charging time increases
Solution Approach 1:
The system employs periodic charge pulses with on/off cycles rather than continuous charging. This pulsing approach allows the battery to rest between charge pulses, reducing stress and improving lifespan, while maintaining high average charging current to minimize charging time
Solution Approach 2:
The system applies preliminary high current charging when the battery voltage is low and the battery can accept high current. This preliminary fast charging reduces overall charging time, while subsequent current reduction at higher voltages protects battery lifespan
3Productivity
If high charge current is applied to a battery, then charging speed is improved, but lithium-ion concentration gradients increase causing battery stress
Solution Approach 1:
The periodic charge pulses with rest periods allow lithium ions to redistribute within the battery during off periods, reducing concentration gradients that would otherwise build up during continuous high-current charging, thus minimizing battery stress while maintaining fast charging capability
Data Source
AI summary
This document discusses, among other things, apparatus and methods to optimize charging of a battery, including providing a first charge profile configured to provide charge current pulses to a battery in a plurality of steps. In the first charge profile, the charge current pulses can be stepped down in the plurality of steps using a comparison of a terminal voltage of the battery to a clamp voltage. When the terminal voltage meets or exceeds the clamp voltage, a high time current of the charge current pulse can be decreased and the clamp voltage can be increased before providing a subsequent charge current pulse.