Voltage-Based Battery Capacity Estimation Without Sense Resistors
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Solution Overview
Problem
Existing battery management systems require direct current measurement using sense resistors, which consume power, occupy space, and increase costs, and also necessitate costly configuration and programming, making them undesirable for many applications.
Innovation Solution
A controller estimates a scale factor and current rate using multiple battery voltage values and models during steady and dynamic operations, allowing for accurate remaining capacity estimation without direct current measurement, using a steady state model for discharging and a dynamic model for charging, and updating the scale factor to accommodate variations in battery parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If direct current measurement using sense resistors is used, then accurate current flow information is obtained, but power consumption increases, circuit board space is occupied, and system cost increases
Solution Approach 1:
The patent extracts the current measurement function from the traditional sense resistor approach and implements it through voltage-based estimation using the relationship V=IR. By measuring voltage across the battery terminals and using the known battery impedance, the system derives current information without requiring a dedicated current sensing component, thereby eliminating the power consumption and space requirements of sense resistors.
Solution Approach 2:
The patent introduces voltage measurement as an intermediary to obtain current information. Instead of directly measuring current with a sense resistor, the system measures voltage across the battery terminals and uses the battery's internal impedance characteristics to calculate current. This intermediary approach allows current estimation without the drawbacks of direct current measurement.
2Measurement precision
If direct current measurement using sense resistors is used, then accurate current flow information is obtained, but circuit board space is occupied
Solution Approach 1:
The patent removes the sense resistor component from the circuit board by replacing it with a voltage-based current estimation algorithm. The current measurement functionality is extracted from the hardware domain and implemented in the software/domain of voltage measurement and calculation, eliminating the need for additional circuit board space.
Solution Approach 2:
The voltage measurement capability, which is already present in the battery management system for monitoring battery state, is made multi-functional by using it both for voltage monitoring and for current estimation. This eliminates the need for separate current sensing circuitry and reduces overall system complexity and space requirements.
3Measurement precision
If direct current measurement using sense resistors is used, then accurate current flow information is obtained, but system cost increases
Solution Approach 1:
The patent extracts the current sensing functionality from the hardware component (sense resistor) and implements it through software-based voltage measurement and calculation. This eliminates the need to procure, stock, and assemble additional hardware components, thereby reducing manufacturing costs and simplifying the supply chain.
Solution Approach 2:
The patent replaces the expensive sense resistor hardware with a software-based estimation algorithm that utilizes existing voltage measurement capabilities. This software-based approach is significantly cheaper than hardware current sensing solutions while providing sufficient accuracy for battery management applications.
4Measurement precision
If configuration or programming of battery management circuits is performed, then accurate battery parameters are obtained, but the process becomes costly and undesirable
Solution Approach 1:
The patent implements a self-service approach where the battery management system automatically determines battery parameters through voltage-based measurements and calculations during normal operation. The system self-calibrates and adapts to the specific battery characteristics without requiring external configuration or programming, eliminating the need for costly setup processes.
Solution Approach 2:
The patent uses parameter changes in the voltage measurements over time and under different operating conditions to automatically characterize the battery. By monitoring voltage responses during charging and discharging cycles, the system dynamically determines battery impedance and capacity parameters without requiring pre-programming or configuration steps.
Data Source
AI summary
Controllers and methods to manage a battery, in which a controller estimates scale factor and a steady state current rate according to multiple battery voltage values and a steady state model during steady state operation, and estimates the current rate according to a battery voltage value, the scale factor, and a dynamic model of the battery during dynamic operation, and the controller estimates a remaining capacity of the battery according to the current rate, without requiring controller reconfiguration for different batteries.