Battery String Charge Equalization via Average Potential Comparison
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Solution Overview
Problem
Existing charge equalization apparatuses for series-connected battery strings often discharge energy from relatively low-charged battery cells when comparing potentials between adjoining cells, leading to inefficiencies and complexity, especially when some cells are low-charged simultaneously.
Innovation Solution
A charge equalization apparatus and method that compares the potential of each battery cell with the average potential of the total battery string, using an automatic PWM generating means to control a DC/DC converter to charge or discharge cells, ensuring energy is not discharged from low-charged cells and balancing potentials across the string.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If charge equalization is performed by comparing potentials between adjoining battery cells, then charge equalization can be achieved, but energy is discharged from low-charged cells leading to charge inefficiency
Solution Approach 1:
Instead of comparing potentials between adjoining cells and discharging from lower potential cells, the invention inverts the approach by comparing each cell's potential with the average potential and selectively charging only those cells below the average, thereby eliminating unnecessary energy discharge from already low-charged cells
Solution Approach 2:
The system continuously monitors individual cell potentials, compares them with the calculated average potential, and dynamically adjusts charging actions based on this feedback loop, ensuring that only cells below average potential receive charge while cells above average potential remain undisturbed
2Reliability
If charge equalization apparatus compares adjoining cell potentials, then charge balancing can be performed, but the apparatus becomes complex when multiple cells are low-charged simultaneously
Solution Approach 1:
The invention changes the reference parameter from individual adjoining cell potentials to the average potential of all cells. This single reference value simplifies the control logic regardless of how many cells are low-charged, eliminating the need for complex conditional judgments about multiple low-charged cell scenarios
3Quantity of substance
If traditional charge equalization methods are used, then some batteries can reach prescribed voltage, but over-charging occurs and charge efficiency decreases
Solution Approach 1:
The invention applies localized charging control to individual battery cells based on their specific state relative to the average. Each cell receives charging attention only if it falls below the average potential, allowing precise local intervention without affecting other cells, thereby preventing both over-charging of already charged cells and under-charging of low cells
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 prevents unnecessary discharge from low-charged cells, enhances charge equalization efficiency, and simplifies the apparatus design by directly comparing cell potentials to the average string potential, thereby improving battery health and performance.
Implementation Method 1
a DC/DC converter (320) connected in parallel to each of the batteries composing the battery string
Implementation Method 2
A comparator generates an output signal by comparing a potential of the nth battery cell with an average potential of the battery string
Data Source
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AI summary
The present invention relates to an automatic charge equalization apparatus and method having an automatic PWM generating means for a series-connected battery string. The automatic charge equalization method and apparatus for a series -connected battery string according to the present invention can improve charge equalization by accomplishing charge equalization operation after comparing the potential of the corresponding battery cell with the average potential of the plurality of battery cells including the corresponding battery cell upon charging or discharging the corresponding battery cell.