Battery Current Sensor Offset Correction Under Changing Charge Flow
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Solution Overview
Problem
Existing methods struggle to correct the offset in current measurement devices when the charging/discharging current is constantly changing, making it difficult to determine the appropriate timing for offset correction.
Innovation Solution
A battery management system that includes an acquisition section for measuring charging current, an estimation section using a characteristic map to estimate the current value, and a correction section to correct the offset in the current measurement device based on the estimated current value and measurement value.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset correction is performed using conventional methods (when current is zero or known), then measurement precision is improved, but the method cannot be applied when charging/discharging current is constantly changing
Solution Approach 1:
The system performs preliminary action by estimating the true current value using a characteristic map before offset correction is needed. The characteristic map pre-stores the relationship between voltage, temperature, SOC, and current, allowing the system to retrieve an estimated current value whenever correction is needed, rather than waiting for specific conditions like zero current.
Solution Approach 2:
The characteristic map acts as an intermediary between the known battery parameters (voltage, temperature, SOC) and the unknown true current value. Instead of directly measuring or knowing the current, the system uses the characteristic map to mediate and estimate the current value, which then enables offset correction under any operating condition.
2Measurement precision
If offset correction timing is based on known current values (e.g., zero current), then correction accuracy is improved, but correction cannot be performed during constant current changes
Solution Approach 1:
The characteristic map is prepared in advance with pre-calculated current values based on battery characteristics. This preliminary action allows the system to immediately retrieve accurate current estimates at any moment without waiting for specific timing conditions, eliminating the time loss associated with waiting for zero-current or known-current states.
Solution Approach 2:
The system changes the approach from relying on specific operational parameters (zero current, known current) to using battery state parameters (voltage, temperature, SOC) that are continuously available. By shifting from current-based correction timing to state-based continuous estimation, the system eliminates timing restrictions while maintaining correction accuracy.
3Speed
If current measurement is continuously monitored, then real-time correction capability is improved, but without a reference current value, offset cannot be corrected
Solution Approach 1:
The characteristic map serves as an intermediary that provides the missing reference current value. Instead of requiring direct current measurement or known current conditions, the system uses the characteristic map to generate a reference current estimate based on readily available battery state parameters, enabling both continuous monitoring and accurate correction.
Solution Approach 2:
The system replaces the mechanical/physical requirement for known current conditions with an information-based approach using the characteristic map. Instead of waiting for specific electrical conditions (zero current, known current), the system substitutes this with computational estimation based on voltage, temperature, and SOC data, achieving continuous correction capability.
Data Source
AI summary
Provided are a battery management system and a vehicle each capable of correcting an offset in a current measurement device even in a case where a charging/discharging current is constantly changing. The battery management system includes: an acquisition section that acquires, in a case where a charging current flowing from a charger to a battery is measured by a current measurement device, a measurement value measured by the current measurement device; an estimation section that estimates a current value of the charging current by referring to a characteristic map, which indicates a characteristic of the battery, based on a known value of a current flowing from the charger; and a correction section that corrects an offset in the current measurement device based on the current value having been estimated and the measurement value.