High-Voltage Battery Pack Measurement Using Resistance Ratios
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Solution Overview
Problem
Existing high voltage battery pack measurement systems face inaccuracies due to instability and drift of components over time, leading to increased costs and reduced reliability in measuring battery pack voltages, which is critical for the performance and longevity of electric and hybrid electric vehicles.
Innovation Solution
A method and system that measure voltage ratios during system power-up or wake-up periods using integrated circuits and analog-to-digital converters to determine resistance ratios, allowing for precise voltage measurements of high voltage battery packs, immune to environmental effects and component drift, by generating and measuring reference voltages and calculating resistance ratios to accurately determine positive and negative high voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement systems are used for high voltage battery packs, then the system is simpler and less costly, but measurement precision deteriorates due to component instability and drift over time
Solution Approach 1:
The system performs preliminary calibration during manufacturing to determine resistance ratios before components are installed in the vehicle. This pre-characterization of the measurement circuitry allows the system to compensate for component variations and drift over time, maintaining measurement precision without requiring complex real-time calibration mechanisms.
Solution Approach 2:
The system uses measured reference voltages to calculate resistance ratios and applies these ratios as correction factors in the voltage measurement calculations. This feedback mechanism allows the system to automatically compensate for component drift and environmental effects, maintaining accuracy throughout the battery pack's operational life.
2Reliability
If conventional measurement systems are used, then device complexity is lower, but reliability worsens due to component drift and environmental sensitivity
Solution Approach 1:
The system performs preliminary calibration during manufacturing to determine resistance ratios before components are installed in the vehicle. This pre-characterization of the measurement circuitry allows the system to compensate for component variations and drift over time, maintaining measurement precision without requiring complex real-time calibration mechanisms.
Solution Approach 2:
The system changes the measurement approach by using resistance ratios derived from reference voltage measurements instead of relying on fixed, absolute resistance values. This parameter transformation makes the measurement system immune to environmental effects and component aging, significantly improving reliability.
3Measurement precision
If traditional voltage measurement methods are used, then the system is simpler to implement, but measurement precision deteriorates due to environmental effects and component drift
Solution Approach 1:
The system performs preliminary calibration during manufacturing to determine resistance ratios before components are installed in the vehicle. This pre-characterization of the measurement circuitry allows the system to compensate for component variations and drift over time, maintaining measurement precision without requiring complex real-time calibration mechanisms.
Solution Approach 2:
The system uses a simplified measurement approach that copies the resistance ratio information from the calibration phase and applies it during operation. Instead of requiring complex real-time measurements of all circuit parameters, the system uses the pre-determined resistance ratios to accurately calculate battery voltages from simple reference voltage measurements.
Data Source
AI summary
An apparatus includes a first analog-to-digital converter configured to measure a first reference voltage and a third reference voltage. The apparatus also includes a second analog-to-digital converter configured to measure a second reference voltage and a fourth reference voltage. The apparatus also includes a controller configured to calculate a first resistance ratio, and determine a positive high voltage associated with the positive high voltage direct current input signal based, at least in part, on the first resistance ratio. The controller is further configured to calculate a second resistance ratio, and determine a negative high voltage associated with the negative high voltage direct current input signal based, at least in part, on the second resistance ratio.