Pulse Modulation Charging Reduces Battery Polarization
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Solution Overview
Problem
Continuous and fixed current charging methods for rechargeable batteries lead to electrode polarization, reducing charge efficiency and making it difficult to charge batteries close to saturation, resulting in prolonged charging times and reduced capacity.
Innovation Solution
A pulse modulation charging method and apparatus that uses a charge-discharge cycle with a charge current pulse width greater than the discharge current pulse width, and adjusts the duty cycle based on terminal voltage thresholds to reduce electrode polarization and optimize charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If continuous and fixed current charging method is used, then charging process is simple, but electrode polarization occurs reducing charge efficiency
Solution Approach 1:
The patent applies periodic pulse current charging instead of continuous fixed current charging. The charging current is delivered in periodic pulses with specific duty cycles, allowing the battery electrodes to periodically relax between pulses. This periodic action reduces electrode polarization by providing intervals where ion diffusion can occur without continuous current drive, thereby maintaining higher charge efficiency throughout the charging process.
2Device complexity
If continuous and fixed current charging method is used, then charging method is simple, but charging time becomes prolonged when battery capacity approaches saturation
Solution Approach 1:
The patent implements dynamic adjustment of pulse width modulation (PWM) duty cycle based on battery charge state. As the battery approaches saturation, the control system dynamically reduces the charging current duty cycle to prevent excessive polarization and voltage rise. This dynamic adaptation allows the system to maintain optimal charging current throughout the charging process, significantly reducing total charging time compared to fixed current methods while managing the complexity through automated control.
3Quantity of substance
If battery capacity is charged close to saturation with fixed current method, then battery capacity is maximized, but charge efficiency suddenly reduces sharply
Solution Approach 1:
The patent employs feedback control mechanisms that continuously monitor battery terminal voltage and charge current. When the battery approaches saturation and voltage rises indicating reduced charge efficiency, the system automatically adjusts the PWM duty cycle to reduce charging current. This feedback loop ensures the battery can be charged close to saturation while maintaining acceptable charge efficiency by preventing the sharp efficiency drop that occurs with fixed current methods at high state of charge.
Data Source
AI summary
A pulse modulation charging method is provided for charging a rechargeable battery device. In the method, a current pulse is provided according to a charge-discharge cycle, the rechargeable battery device is charged repeatedly with a charge current pulse width, and the rechargeable battery device is discharged with a discharge current pulse width. In addition, in the method one or more voltage threshold values are further designated. When a terminal voltage of the rechargeable battery device is greater than the voltage threshold value, the charge current pulse width is gradually reduced, so as to improve charge efficiency for charging the rechargeable battery device. A pulse modulation charging apparatus is further provided, which is used for charging the rechargeable battery device according to the steps described here.