Capacitive Cell Balancing Circuitry for Battery Packs
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Solution Overview
Problem
Existing battery pack technologies face inefficiencies in balancing the state of charge and voltage across cells, leading to uneven charging and discharging, which can result in reduced battery life and energy wastage due to passive cell balancing methods that divert energy as heat.
Innovation Solution
The development of a cell balancing circuitry that uses a switch network and capacitors to transfer energy between cells, allowing for active balancing by synchronizing switch operations with a clock signal to equalize the state of charge and voltage across cells without energy loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If passive cell balancing methods are used to balance cell voltages, then cell voltage equality is improved, but energy is wasted as heat
Solution Approach 1:
The patent introduces capacitors as intermediary energy storage elements between cells. These capacitors temporarily store energy from cells with higher state of charge and transfer it to cells with lower state of charge, enabling active balancing without energy waste as heat.
Solution Approach 2:
The patent replaces the passive resistive balancing mechanism (which dissipates energy as heat) with an active capacitive energy transfer mechanism. This substitution transforms the balancing process from a dissipative system to a conservative system where energy is preserved and redistributed.
2Loss of energy
If cell balancing circuitry is added to enable active balancing, then energy efficiency is improved, but device complexity increases
Solution Approach 1:
The patent divides the balancing function into modular switching elements and capacitor units that can be selectively activated. The switch network is configured to connect capacitors to specific subsets of cells, allowing localized balancing operations rather than requiring a complete system-wide restructuring.
Solution Approach 2:
The patent employs periodic switching operations synchronized with a clock signal to enable capacitive energy transfer between cells. This periodic action allows the system to achieve balancing through repeated charge-discharge cycles of the capacitors, managed by controlled switching sequences.
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
This solution enhances battery life by efficiently balancing cell voltages and states of charge, reducing the frequency of recharging and minimizing energy wastage, thereby improving the environmental impact and performance of battery packs.
Implementation Method 1
a set of capacitors coupled in parallel between the switch network and a common node
Data Source
AI summary
Balancing circuitry for balancing a set of N cells in a battery, the balancing circuitry comprising: a switch network configured to be coupled to the cells; and a set of capacitors coupled in parallel between the switch network and a common node, wherein the switch network is controllable such that: during a first phase of operation of the balancing circuitry the set of capacitors is coupled to a first subset comprising N−1 adjacent cells of the set of N cells; and during a second phase of operation the set of capacitors is coupled to a second subset comprising N−1 adjacent cells of the set of N cells, wherein the second subset is different from the first subset, and wherein, in use of the balancing circuitry, the common node is coupled intermittently, periodically or permanently to a reference voltage.