Battery SOC Estimation Using Temperature and Voltage Data
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Solution Overview
Problem
Existing battery sense systems for portable electronic devices are often inaccurate and inefficient, requiring additional bulky and costly circuit components to measure battery capacity.
Innovation Solution
A battery sense system that includes a temperature sensor and a controller to calculate the state of charge (SOC) of a battery using a dynamic battery model, which models steady-state and transient behaviors based on voltage, temperature, and depth of discharge (DOD) data stored in memory, allowing for accurate SOC estimation without the need for additional current sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional battery sense systems use additional circuit components to measure battery capacity, then measurement capability is provided, but device complexity, cost, and power consumption increase
Solution Approach 1:
The patent extracts the battery sensing function from dedicated hardware circuitry and relocates it to software-based processing. The controller uses existing voltage measurements combined with lookup tables and algorithms to calculate SOC, eliminating the need for separate current sensors and complex analog circuitry while maintaining measurement capability
Solution Approach 2:
The patent replaces physical/mechanical sensing components with computational methods. Instead of using hardware circuits to directly measure battery capacity, the system uses software algorithms that process voltage data and temperature information to compute SOC, substituting electronic computation for electronic sensing hardware
2Measurement precision
If traditional battery sense systems use additional circuit components, then battery capacity can be measured, but power consumption increases
Solution Approach 1:
The patent removes power-hungry sensing circuitry from the system and replaces it with computational processing that uses the existing voltage measurement infrastructure. The lookup tables and algorithms run on the controller using minimal additional power compared to dedicated sensing hardware
Solution Approach 2:
The system uses the existing voltage measurement capability of the battery management system to derive capacity information. Rather than adding separate sensing components that consume power, the system makes the existing voltage measurements serve dual purposes: both for basic battery management and for SOC calculation
3Device complexity
If simple voltage-based SOC calculation is used, then device complexity is reduced, but measurement accuracy deteriorates due to temperature and transient effects
Solution Approach 1:
The patent performs preliminary characterization of battery behavior across different temperatures and discharge rates during manufacturing or initial setup. Lookup tables are pre-computed containing voltage-SOC relationships for various temperature conditions, allowing the system to compensate for temperature effects without real-time complex calculations
Solution Approach 2:
The system dynamically selects appropriate lookup tables and calculation methods based on current operating conditions such as temperature and discharge rate. The controller adapts its SOC calculation approach according to the battery's transient state, using different algorithms for steady-state versus transient conditions to maintain 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 provides accurate battery capacity estimation, is cost-effective, and efficient, as it accounts for temperature-dependent resistance and voltage changes, improving upon traditional methods by eliminating the need for extra circuitry and enhancing accuracy in SOC calculation.
Implementation Method 1
a temperature sensor configured to measure a temperature of the battery
Implementation Method 2
batteries that generate a voltage based on chemical reactions
Data Source
AI summary
One embodiment of the invention includes a battery sense system. The system includes a temperature sensor configured to measure a temperature of a battery and a memory configured to store predetermined data associated with steady-state and transient behaviors of the battery relative to a depth of discharge (DOD) of the battery. The system also includes a controller configured to measure a voltage of the battery and to calculate a state of charge (SOC) of the battery based on the voltage, the predetermined data, and the temperature.