Battery Capacity Estimation Using Dual Current Measurement
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Solution Overview
Problem
Existing battery management devices struggle to accurately measure the remaining capacity of batteries due to increased self-consumption currents, which were previously negligible compared to load currents, leading to inaccurate calculations of full-charge capacity and remaining battery capacity.
Innovation Solution
Incorporating a current measurement circuit to measure both the current supplied to a load and the self-consumption current of the battery management device, and a computing circuit to calculate the remaining battery capacity based on the accumulation values of these currents during discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the battery management device measures only the load current and ignores self-consumption current, then the device complexity is reduced, but the measurement precision of remaining battery capacity deteriorates
Solution Approach 1:
The current measurement is segmented into two separate measurement paths: one for load current and one for self-consumption current. The current measurement circuit measures both currents separately, and the computing circuit accumulates and calculates each component independently to determine the remaining battery capacity accurately.
2Measurement precision
If the battery management device measures both load current and self-consumption current, then the measurement precision of remaining battery capacity is improved, but the device complexity increases
Solution Approach 1:
The current measurement circuit is designed with multi-functionality to measure both load current and self-consumption current using the same hardware infrastructure. The computing circuit performs multiple functions by accumulating different current components and calculating remaining capacity, reducing the need for separate dedicated measurement systems.
3Productivity
If the battery management device calculates full-charge capacity without considering self-consumption current, then the calculation speed is improved, but the reliability of remaining capacity calculation deteriorates
Solution Approach 1:
The computing circuit performs preliminary accumulation of both load current and self-consumption current during the discharge period. By pre-accumulating these current values, the system prepares the necessary data for accurate full-charge capacity calculation, ensuring reliability while maintaining efficient calculation speed when the actual computation is needed.
Data Source
AI summary
A semiconductor device, a battery pack, a method of controlling the semiconductor device, and a control program capable of accurately measuring a remaining capacity of a battery is provided. The semiconductor device includes: a current measurement circuit configured to measure a current value of a first current supplied from a battery to the semiconductor device that is a host device and a current value of a second current supplied from the battery to a load; and a computing circuit configured to calculate the remaining capacity of the battery, based on an accumulation value of the first current and an accumulation value of the second current in a period from start of discharging to end of discharging in the battery.