Battery Pack Pulse Charging With Interleaved Cell Switching
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Solution Overview
Problem
Existing systems for charging serial-connected battery groups face challenges in maintaining a constant charge current, which can lead to inefficiencies and potential damage to chargers, and do not optimize charging for individual battery cells within a pack.
Innovation Solution
A control circuit and method that utilize switching elements controlled by a control unit to provide pulse charging, ensuring a substantially constant charge current by interleaving ON times and using measurement lines to optimize charging for each battery cell, allowing for advanced pulse charging protocols while maintaining compatibility with traditional charging protocols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional charging protocols are used for serial-connected battery groups, then charging simplicity is maintained, but charge current becomes non-constant leading to charger damage and inefficiency
Solution Approach 1:
The patent applies periodic pulse charging by switching between charging and non-charging states at regular intervals. The charger delivers charge current in pulses rather than continuously, creating a periodic charging pattern that prevents overheating and damage while maintaining effective charging of the battery pack.
Solution Approach 2:
The patent implements dynamic control of the charging process by adjusting the duty cycle of pulse charging based on real-time battery state monitoring. The control unit modifies charging parameters dynamically during operation to maintain constant average charge current and adapt to changing battery conditions, ensuring both safety and efficiency.
2Loss of energy
If pulse charging with duty cycle control is used, then thermal emission from switch resistance is reduced, but charging efficiency decreases due to intermittent charging
Solution Approach 1:
The patent maintains continuous useful action by ensuring that at least one battery group is always being charged during the pulse charging cycle. While some groups may be in non-charging states, others continue to receive charge current, eliminating idle time and maintaining continuous charging progress across the battery pack.
Solution Approach 2:
The control unit dynamically adjusts the duty cycle and pulse parameters based on real-time monitoring of battery state, temperature, and charge current. This dynamic optimization ensures that the pulse charging delivers maximum effective charge while minimizing thermal losses, adapting the charging pattern to maintain high efficiency throughout the charging process.
3Productivity
If individual battery cell optimization is implemented, then charging performance is maximized, but system complexity increases due to multiple measurement and control requirements
Solution Approach 1:
The patent segments the battery pack into multiple independently controllable battery groups, each with its own measurement and control capabilities. This segmentation allows individual optimization of each group's charging parameters while maintaining overall system coordination, enabling efficient parallel charging of multiple groups with different states of charge.
Solution Approach 2:
The control unit is designed with multi-functionality to handle diverse charging scenarios. It can simultaneously monitor multiple battery groups, implement different charging strategies for different groups based on their individual states, and coordinate pulse charging across all groups. This universal control capability manages complexity through integrated multi-functional design rather than separate dedicated systems.
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A battery pack comprises series-connected battery groups (1-M). At least one battery group comprises one or more high charge rate battery cells (81,81a; 82,82a) with first battery switches (85;86), and one or more regular charge rate battery cells (83,83a; 84) with second battery switches (87;88). A controller (2) produces pulsed switching signals to control the battery switches (85-88), each pulsed switching signal corresponding to one of the battery switches (85-88). The controller partially charges the battery pack (1) using an ultra high charging rate for the high charge rate battery cells (81, 81a; 82, 82a). Then the controller switches in the regular charge rate battery cells (83,83a; 84) via the second battery switches (87;88). The ON times of switches (85-88) overlap, to ensure that there is always at least one battery switch (85-88) in each battery group in a closed state, at all times during charging of the battery pack (1).