Parallel Battery Charging With PWM Balancing for Foldable Devices
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Solution Overview
Problem
Foldable electronic devices with physically separated batteries of different capacities face challenges in cell balancing due to impedance asymmetry, leading to current asymmetry during charging and discharging, which affects battery stability and lifespan.
Innovation Solution
An electronic device with a first and second battery connected in parallel, featuring a charger, voltage detection circuit, and a balancing circuit that uses pulse width modulation (PWM) to control the connection between the batteries based on voltage differences, reducing current asymmetry and enhancing stability and lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If physically separated batteries with different capacities are connected in parallel, then the device can be folded/unfolded with flexible battery placement, but impedance asymmetry causes current asymmetry during charging/discharging
Solution Approach 1:
The patent implements a feedback mechanism where a control circuit continuously monitors the voltage of each battery and adjusts the connection state of switching elements accordingly. When voltage difference exceeds a threshold, the control circuit activates balancing operations to equalize voltages, thereby eliminating current asymmetry caused by impedance differences while maintaining the flexible parallel connection architecture
Solution Approach 2:
The patent employs dynamic switching elements (MOSFETs or relays) that can change their connection state based on real-time battery voltage conditions. These switching elements dynamically adjust the parallel connection configuration between batteries, transitioning between connected and disconnected states to balance current distribution and prevent stability issues arising from fixed asymmetric connections
2Quantity of substance
If physically separated batteries with different capacities are connected in parallel, then battery capacity can be increased, but impedance asymmetry leads to current asymmetry and reduced battery lifespan
Solution Approach 1:
The control circuit continuously monitors battery voltages and compares them against reference values to detect asymmetry conditions. When voltage imbalance is detected, the feedback mechanism triggers balancing operations by adjusting switching element states, ensuring that batteries with different capacities operate within safe current ranges and thereby extending overall system lifespan
Solution Approach 2:
The patent introduces switching elements as intermediary components between the parallel-connected batteries and the load/charger. These intermediaries act as controllable gates that regulate current flow to each battery, preventing harmful current asymmetry while allowing the system to utilize the combined capacity of multiple batteries with different ratings
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
The solution effectively reduces current asymmetry, thereby increasing battery stability and extending the lifespan of batteries with different capacities connected in parallel.
Implementation Method 1
a voltage detection circuit configured to detect a voltage of the first battery and a voltage of the second battery
Implementation Method 2
a balancing circuit disposed between the first node and the first battery and configured to control a connection between the first node and the first battery in a pulse width modulation (PWM) method
Data Source
AI summary
An electronic device for charging a plurality of batteries is provided. The electronic device includes a first battery, a second battery parallelly connected to the first battery, wherein the first battery and the second battery are branched at a first node, a charger for charging the first battery and the second battery by means of a current input from an external device, a voltage detection circuit for detecting the voltage of the first battery and the voltage of the second battery while the first battery and the second battery are being charged, and a balancing circuit disposed between the first node and the first battery, and for controlling the connection between the first node and the first battery by means of pulse width modulation (PWM) based on detecting a differential between the voltage of the first battery and the voltage of the second battery.