Battery Cell Balancing Using Isolated Active Charging
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Solution Overview
Problem
Batteries tend to become unbalanced due to mismatched states of charge (SOCs) among their cells, leading to premature capacity loss and reduced lifespan, with passive balancing methods being inefficient as they waste electrical energy by converting it to heat.
Innovation Solution
A system that actively balances batteries by directing energy to individual cells with lower SOC using voltage sensors, switches, and a controller to charge them, rather than passively draining energy from higher SOC cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive balancing is used to balance batteries, then battery balance is restored, but electrical energy is wasted and converted to heat
Solution Approach 1:
Instead of draining energy from higher SOC cells to balance the battery (passive approach), the invention inverts the approach by actively charging lower SOC cells to bring them up to the level of higher SOC cells. This is achieved by using a power supply to direct current to individual cells that need charging, thereby restoring battery balance without wasting energy as heat.
2Reliability
If passive balancing drains all cells to the lowest SOC level, then perfect balance is achieved, but efficiency is severely reduced
Solution Approach 1:
The invention applies local quality by treating each cell individually based on its specific SOC level. Rather than uniformly draining all cells to the lowest level, the system identifies specific cells with lower SOC and directs charging current only to those cells. This selective approach maintains precise balance while significantly improving efficiency by avoiding unnecessary energy transfer from cells that are already at acceptable charge levels.
3Loss of energy
If active balancing charges individual lower SOC cells, then energy efficiency is improved, but system complexity increases
Solution Approach 1:
The invention introduces intermediary components (controller, voltage sensors, and switching mechanism) that mediate between the power supply and individual cells. The controller receives voltage measurements from sensors, determines which cells require charging, and uses switches to connect the power supply to specific cells. This intermediary layer manages the complexity of selective cell charging while enabling high energy efficiency.
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 approach efficiently maintains battery balance without wasting energy, effectively addressing out-of-balance conditions, particularly in batteries with leaky cells, thereby extending their lifespan.
Implementation Method 1
Voltage sensors are connected in parallel to each cell
Implementation Method 2
The power supply can provide a current source to the cells
Implementation Method 3
A pair of switches is connected to each cell; one switch is connected to the negative terminal of each cell and one switch is connected to the positive terminal of each cell
Data Source
AI summary
An apparatus and method of balancing cells in a battery using an isolated power supply and pairs of switches to direct power to cells at a lower state of charge to bring them into balance with cells at a higher state of charge.