Floating Battery Voltage Measurement Using Charge Transfer Capacitors
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Solution Overview
Problem
Measuring battery voltage in battery banks with floating batteries connected in series or parallel poses challenges due to high voltages, often requiring expensive circuitry or significant power consumption.
Innovation Solution
A system comprising a first floating capacitor and a second fixed-reference capacitor, with switches to selectively couple and decouple them, allowing charge transfer and voltage measurement across batteries without direct reference to ground, using transistors and a buffer for sampling and output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If expensive circuitry is used to measure battery voltage, then measurement precision is improved, but device cost increases
Solution Approach 1:
The patent introduces a voltage divider circuit as an intermediary mechanism between the floating battery terminals and the measurement circuitry. This voltage divider reduces the high floating voltage to a lower, safer level that can be measured by standard, less expensive ADC circuits, thereby achieving precise measurement without requiring expensive high-voltage rated circuitry
Solution Approach 2:
The measurement system is segmented into distinct functional blocks: a voltage divider network for level reduction, switching circuitry for signal routing, and an ADC for measurement. This segmentation allows each component to be optimized independently and reduces overall system complexity compared to a monolithic high-voltage measurement solution
2Measurement precision
If high-power circuitry is used to measure battery voltage, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent employs periodic switching of the voltage divider network into and out of the measurement circuit. The voltage divider is activated only during measurement intervals when the ADC needs to read the voltage, and deactivated during other times. This periodic operation significantly reduces average power consumption compared to continuous high-power measurement circuitry while maintaining measurement precision when needed
3Ease of operation
If direct ground reference is used for measurement, then measurement simplicity is improved, but adaptability to floating batteries deteriorates
Solution Approach 1:
The patent implements dynamic switching that allows the measurement circuit to adapt between different operating modes. The voltage divider network can be selectively connected to floating battery terminals or disconnected, allowing the same circuit to handle both floating and grounded battery configurations. This dynamic reconfigurability provides versatility without sacrificing measurement simplicity
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
Enables precise and efficient measurement of battery voltage across floating batteries, reducing the need for expensive circuitry and power consumption while maintaining accuracy.
Implementation Method 1
a first capacitor configured to receive a charge from a battery
Implementation Method 2
a second switch configured to selectively couple the second capacitor to the first capacitor to transfer at least a portion of the charge on the first capacitor to the second capacitor
Data Source
AI summary
An apparatus and method for measuring battery voltage includes a first capacitor configured to receive a charge from a battery. A first switch may be configured to selectively couple the first capacitor to the battery. A second capacitor may be coupled to a reference potential. A second switch may be configured to selectively couple the second capacitor to the first capacitor to transfer at least a portion of the charge on the first capacitor to the second capacitor.