Battery Pack Current Detection Accuracy via Segmented Measurement
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Solution Overview
Problem
In battery packs for electric power tools, the significant difference between charge and discharge currents leads to inaccurate detection of remaining battery capacity due to the need for a single electric-current detection unit to handle a wide range of currents, resulting in lower detection accuracy for lower current values.
Innovation Solution
A measurement system with multiple detection devices having different measurement ranges is employed, where one device detects high currents and another detects low currents, allowing for accurate detection of physical quantities like electric current by using the appropriate device based on the current range, and transmitting results to a processing unit for precise calculation of remaining battery capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electric-current detection unit is used to detect both charge current and discharge current, then the device complexity is reduced, but the measurement precision deteriorates due to the wide range of currents
Solution Approach 1:
The patent divides the current detection function into multiple detection units, each responsible for a specific current range. The first detection unit detects charge current (typically 0-10A) while the second detection unit detects discharge current (typically 0-100A). This segmentation allows each unit to be optimized for its specific range, improving measurement precision without requiring an overly complex single-unit design.
2Adaptability or versatility
If the measurement range of the detection unit is increased to cover both charge and discharge currents, then the adaptability is improved, but the measurement precision deteriorates for lower current values
Solution Approach 1:
The patent applies local quality by giving each detection unit specialized characteristics suited to its detection target. The first detection unit is optimized with higher precision components for detecting small charge currents, while the second detection unit uses components suited for handling large discharge currents. This localized optimization ensures high precision in each specific application area.
Solution Approach 2:
The system dynamically switches between different detection units based on the operational state. The control unit determines whether the battery is charging or discharging and activates the appropriate detection unit accordingly. This dynamic adaptation allows the system to maintain high measurement precision across the full current range by always using the optimally suited detection unit.
Data Source
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AI summary
A measurement system (1, 3; 5) according to one aspect of the present invention includes a battery pack (1) and at least one type of connected device (3; 5) to which the pack (1) is connected. The pack (1) includes a first detection device (14) detecting a predetermined physical quantity in the pack (1) and having a predetermined measurement range. The connected device (3; 5) includes a second detection device (34; 54) detecting a physical quantity the same as the predetermined physical quantity and having a measurement range different from the range of the first detection device (14). One of the pack (1) and the connected device (3; 5) includes a receiving device (13) and a measurement processing device (13) that performs a predetermined measurement process by using one of: a detection-value-related information received by the receiving device (13); and a detection result by one device of the first detection device (14) and the second detection device (34; 54), the one device being provided in one of the pack and the connected device.