Multi-Cell Battery Voltage Balancing With Self-Calibrated Sensing
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Solution Overview
Problem
Existing methods for balancing voltages in multicell batteries are costly and prone to inaccuracies due to the use of high-resolution ADCs or complex analog circuits, leading to potential battery failure, reduced capacity, and safety risks.
Innovation Solution
A system using a resistor ladder, voltage-controlled oscillators (VCOs) or ADCs, and a logic circuit for self-calibration to determine relative cell voltages, correcting for inaccuracies through offset calculations and temperature compensation, ensuring balanced cell voltages without the need for expensive high-precision components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-resolution ADCs (14-16 bit) are used to measure cell voltage accurately, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The patent replaces expensive, complex high-resolution ADCs with inexpensive, simple voltage dividers and microcontroller ADCs. The voltage dividers use basic resistors to scale down cell voltages, and the microcontroller's built-in ADC (typically 10-12 bit) performs the measurement. This substitution dramatically reduces component cost and circuit complexity while maintaining sufficient measurement accuracy for battery management applications.
Solution Approach 2:
The patent changes the measurement approach by using voltage dividers to scale voltages before measurement, allowing the use of lower-resolution ADCs. Additionally, the system performs multiple measurements and uses software-based compensation techniques to achieve accurate cell voltage readings without requiring high-resolution hardware ADCs.
2Measurement precision
If high-resolution ADCs with extensive test and trimming are used during manufacturing, then measurement precision is improved, but manufacturing cost and time increase
Solution Approach 1:
By using inexpensive voltage dividers and standard microcontroller ADCs, the patent eliminates the need for expensive manufacturing test and trimming processes that would be required for high-resolution ADCs. The simple circuit topology and robust measurement algorithm allow for straightforward production testing without complex calibration equipment or procedures.
Solution Approach 2:
The system performs self-calibration by measuring a known reference voltage (such as a bandgap reference or a precisely regulated voltage) during initialization. The microcontroller uses this reference measurement to calculate compensation factors that are stored in memory, enabling the system to compensate for component tolerances without requiring external calibration equipment or manual trimming during manufacturing.
3Measurement precision
If ADC inaccuracy is present in measuring cell voltage, then measurement precision deteriorates, but the patent compensates through self-calibration and offset calculations
Solution Approach 1:
The system performs self-calibration by measuring a known reference voltage and using this measurement to calculate compensation factors. These factors are stored in the microcontroller's memory and applied to subsequent cell voltage measurements to correct for systematic errors in the voltage dividers and ADC, thereby maintaining high measurement accuracy despite component tolerances and environmental variations.
Solution Approach 2:
The system continuously monitors cell voltages and compares them against expected values based on the battery's state of charge and operating conditions. When discrepancies are detected, the system adjusts measurement parameters or applies software-based compensation to maintain accuracy. The self-calibration process also uses feedback from the reference voltage measurement to automatically adjust offset and gain parameters.
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
Achieves accurate and cost-effective voltage balancing in multicell batteries, reducing the risk of failure and enhancing safety by maintaining balanced cell voltages within a few percent of each other, while minimizing component costs and complexity.
Implementation Method 1
voltage-controlled oscillators (VCOs) or ADCs
Data Source
AI summary
A method for measuring electrical quantities in an electrical system includes obtaining a first set of known electrical outputs of an electrical quantity sensor at a first temperature. The method also includes obtaining a second set of known electrical outputs of the electrical quantity sensor at a second temperature that is different from the first temperature. The method further includes measuring an operational temperature of one or more locations in the electrical system. The method still further includes computing a pair of reference electrical output values corresponding to the measured operational temperature in accordance with the first set of known electrical outputs at the first temperature and the second set of known electrical outputs at the second temperature. The method also includes interpolating among the pair of computed reference electrical output values to determine a temperature-corrected electrical quantity based on the measured operational temperature and the reference electrical output values.