Battery Pack Balancing Voltage Drop Compensation
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Solution Overview
Problem
Existing battery management systems for electric vehicles face measurement errors in battery cell voltage due to voltage drops in electrical wires, leading to inaccurate balancing and reduced efficiency, requiring frequent disconnection and reconnection of balancing circuits to minimize errors.
Innovation Solution
A method and system that calibrate electrical wire coefficients by measuring voltage drops when the vehicle is stationary, allowing for continuous balancing by updating coefficients based on temperature changes, enabling accurate voltage compensation without disrupting the balancing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the balancing resistance is connected to discharge overcharged cells, then cell voltage deviations are reduced and battery pack deterioration is prevented, but voltage drops in electrical wires cause measurement errors in cell voltage
Solution Approach 1:
The patent replaces direct voltage measurement with current measurement. Instead of measuring voltage directly (which is affected by wire resistance), the system measures the current flowing through the balancing resistance and calculates voltage from this current measurement, substituting a more accurate measurement approach
Solution Approach 2:
The patent introduces an intermediary measurement approach by measuring current through the balancing resistance rather than directly measuring cell voltage. This intermediary current measurement serves as a proxy that is not affected by wire resistance, allowing accurate voltage calculation
2Measurement precision
If voltage measurement is performed by disconnecting the balancing process, then measurement accuracy is improved, but balancing efficiency is reduced and noise is generated from periodic commutations
Solution Approach 1:
The patent enables continuous balancing operation by measuring current through the balancing resistance without disconnecting or interrupting the balancing process. This maintains continuous useful action while obtaining accurate measurement data for voltage calculation
Solution Approach 2:
The patent substitutes the mechanical disconnection/reconnection process with a continuous electrical measurement process. By measuring current continuously through the balancing resistance, the system eliminates the need for periodic disconnection while maintaining measurement accuracy
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 reduces measurement errors and maintains balancing efficiency by continuously monitoring and compensating for voltage drops, ensuring accurate cell balancing and extending battery pack lifespan.
Implementation Method 1
the resistance of the electrical wires, a tension drop is produced into said electrical wires
Data Source
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AI summary
Battery pack balancing method and system for a vehicle, comprising: - a plurality of battery cells (1), - a battery balancer (2) connected to each battery cell (1) having a resistance RB (3), - a cell monitor (4) configured to measure the voltage of each battery cell (1) and to manage the battery balancer (2), connected through an electrical wire (5) being the resistance of the electrical wire RC (6). The balancing method comprises the following steps: - modelling each electrical wire (5) connecting the cell monitors (4) and the battery cells (1), and - performing a balancing process of the battery cells (1) compensating the error of the voltage measurement.