Battery Pack Current Estimation via Cell Voltage and Internal Resistance
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Solution Overview
Problem
Current battery management systems for electric vehicles and bicycles face challenges in accurately and efficiently managing battery state, particularly in verifying current levels, which is crucial for safety and efficiency, as existing methods rely heavily on current sensors that may malfunction or provide inaccurate readings.
Innovation Solution
A method and apparatus that estimate battery pack current using voltage values from voltage sensors, resistance components, and inductance components within the battery pack, allowing for compensation of current sensor errors and determination of malfunctioning sensors, thereby enabling accurate state of charge, state of health, and state of function assessments without relying solely on current sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current sensors are used to measure battery current, then current verification is straightforward, but the sensors may malfunction or provide inaccurate readings
Solution Approach 1:
The patent introduces voltage sensors as intermediary measurement devices to indirectly determine battery current. Instead of directly measuring current with unreliable current sensors, the system measures voltage across known resistance components (connection tabs, busbars, terminals, inner wires) and calculates current using Ohm's law. This intermediary approach bypasses the unreliable current sensors while still achieving current verification.
Solution Approach 2:
The patent replaces the electrical measurement system (current sensors) with a different physical measurement approach (voltage measurements). By substituting direct current measurement with voltage measurement across resistance components, the system eliminates dependence on malfunctioning current sensors while maintaining current verification capability.
2Reliability
If voltage sensors and resistance components are used to estimate current, then current sensor malfunction is compensated, but the measurement system becomes more complex
Solution Approach 1:
The patent makes voltage sensors perform multiple functions: they measure both battery pack voltage and individual cell voltages. These same voltage measurements are then used to calculate current through resistance components. This multi-functionality eliminates the need for separate current sensors, reducing overall system complexity while improving reliability.
Solution Approach 2:
The battery pack's own resistance components (connection tabs, busbars, terminals, inner wires) serve dual purposes: they are necessary structural elements for battery operation and simultaneously function as measurement elements for current estimation. The system uses the inherent electrical properties of existing components rather than requiring additional dedicated measurement devices.
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 allows for reliable estimation of battery pack current and associated states, ensuring safe and efficient battery management, even when current sensors malfunction, and enables continuous operation of battery systems by compensating for errors and performing cell balancing without current sensor data.
Implementation Method 1
estimating current of the battery pack based on the voltage value of the battery pack, the voltage values of the cells included in the battery pack, and resistance components within the battery pack
Data Source
AI summary
A method and apparatus for estimating current is disclosed. The current estimation apparatus may receive a voltage value of a battery pack and voltage values of cells included in the battery pack, and may estimate a current of the battery pack based on the voltage value of the battery pack, the voltage values of the cells included in the battery pack, and resistance components within the battery pack.