Charge Balancing Circuit for Series-Connected Battery Chains
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Solution Overview
Problem
Charge storage devices experience progressive mismatches in state of charge among elements due to efficiency differences, leading to reduced energy storage capacity and potential over-discharging or over-charging, with existing balancing techniques suffering from high switching losses and inefficiencies.
Innovation Solution
A charge balancing circuit that connects charge storage elements in parallel within and between chains, allowing for sequential redistribution of charge without requiring series switches, using switches and control circuitry to equalize state of charge across elements by connecting them at similar voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If reactive circuit components are used for charge balancing, then charge distribution is improved, but switching losses increase due to high switching frequencies required to minimize component sizes
Solution Approach 1:
The patent extracts the switching operation from the charge balancing function by using a capacitor to store and transfer charge passively. The capacitor is charged from one battery cell and then discharged into another, eliminating the need for high-frequency switching during the actual charge transfer process and thereby reducing switching losses.
Solution Approach 2:
The patent introduces a capacitor as an intermediary element between battery cells. This capacitor acts as a temporary charge storage medium that facilitates charge transfer without requiring direct switching between cells, thus reducing the switching frequency and associated losses while maintaining effective charge balancing.
2Reliability
If switches are used to connect battery cells in parallel for charge balancing, then charge equalization is achieved, but switch resistance causes losses and reduces efficiency
Solution Approach 1:
The patent removes the switching function from the charge balancing path by using a capacitor-based transfer mechanism. Instead of continuously switching to maintain parallel connections, the capacitor is charged and discharged in discrete steps, eliminating resistive losses associated with continuous switch operation.
Solution Approach 2:
The patent maintains continuous charge balancing action through the capacitor's ability to store and release charge. The capacitor remains charged from one cell and can be discharged into another cell without interruption, providing continuous charge transfer without the need for repeated switching operations.
3Volume of moving object
If high switching frequencies are used to minimize reactive component sizes, then component size is reduced, but switching losses increase
Solution Approach 1:
The patent extracts the time-dependent switching operation and replaces it with a passive capacitor-based charge transfer mechanism. This eliminates the need for high-frequency switching to achieve effective charge balancing, allowing for larger but more efficient components that operate at lower frequencies with reduced losses.
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 method effectively reduces charge imbalances among elements, enhancing energy storage capacity and preventing damage by redistributing charge efficiently with lower switching losses compared to traditional reactive element-based methods.
Implementation Method 1
Once the cells are switched into parallel, they are all forced to the same voltage potential, and so charge transfer can take place between them until they reach a similar state of charge to one another.
Data Source
AI summary
There is disclosed a charge balancing circuit (CBC) and method (10, 20) for balancing charge storage elements (CSE1_1, CSE1_2, CSE2_2) of a charge storage device (CSD). The charge storage device comprises at least two series connected chains (CHN1, CHN2) of charge storage elements. The charge balancing circuit (CBC) connects a first charge storage element (CSE1_1) of a first chain (CHN1) in parallel with a first charge storage element (CSE1_2) of a second chain (CHN2) during a first period of time (φ1), and connects the first charge storage element (CSE1_1) of the first chain (CHN1) in parallel with a second charge storage element (CSE2_2) of the second chain (CHN2) during a second period of time (φ2).