Battery Energy Estimation Using SOC and Mid-Voltage Modeling
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Solution Overview
Problem
Existing battery management systems face challenges in accurately estimating available energy due to errors in voltage and current sensors, especially after long distances, leading to incorrect calculations of travelable distance and vehicle control.
Innovation Solution
A battery management apparatus and method that calculates the state of charge, deterioration degree, mid voltage, remaining capacity, and available energy using a battery state calculation unit, mid voltage calculation unit, and available energy calculation unit, allowing for real-time estimation of available energy without relying on constant discharge current assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accumulative consumption energy is calculated by integrating current and voltage measurements over time, then real-time energy monitoring is achieved, but sensor errors accumulate leading to incorrect available energy estimation
Solution Approach 1:
The patent employs feedback mechanisms by continuously monitoring the relationship between state of charge, power consumption, and available energy. The system adjusts calculations based on feedback from the battery's actual state, correcting for sensor drift and accumulation errors by referencing the battery model's expected behavior at different state of charge levels.
Solution Approach 2:
The patent changes the calculation parameters from direct integration of current and voltage to using state of charge as the primary parameter. By calculating available energy as a function of state of charge and power consumption rate rather than integrating raw sensor data, the system avoids accumulation of sensor errors while maintaining real-time monitoring capability.
2Device complexity
If constant discharge current assumption is used for available energy calculation, then calculation complexity is reduced, but accuracy deteriorates when discharge current changes
Solution Approach 1:
The patent transitions from static constant current assumptions to dynamic calculations that adapt to changing discharge currents. The system continuously updates the available energy calculation based on the current power consumption rate and state of charge, allowing accurate energy estimation even when discharge current varies over time.
Solution Approach 2:
The patent changes the calculation approach by using state of charge and power consumption rate as dynamic parameters instead of assuming constant current. This allows the system to calculate available energy accurately under varying discharge conditions without requiring complex integration of time-varying current and voltage measurements.
Data Source
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AI summary
A battery management apparatus 102 is an apparatus which manages a chargeable and dischargeable battery, and includes: a battery state calculation unit 501 which calculates a state of charge SOC representing the state of charge of the battery, and a charge capacity fade SOHQ representing a deterioration degree; a mid voltage calculation unit 502 which calculates a mid voltage that is present between the discharge voltage in a current state of charge of the battery, and a voltage value representing the discharge voltage in a minimum state of charge of the battery; a remaining capacity calculation unit 503 which calculates a remaining capacity of the battery, based on the state of charge SOC and the charge capacity fade SOHQ; and an available energy calculation unit 504 which calculates available energy of the battery, based on the mid voltage and the remaining capacity.