Battery Pack Voltage Measurement Path Selection
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Solution Overview
Problem
Battery packs with a path for measuring battery cell voltage experience leakage current and measurement noise, leading to accelerated discharge and accuracy issues, due to the leakage loop formed between the battery cell and the system.
Innovation Solution
A battery pack and electronic device design featuring a plurality of sub-paths with switches that selectively connect the battery cell to a sensing circuit based on voltage, reducing leakage current and improving measurement accuracy through noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a path for measuring battery cell voltage is implemented, then charging control precision is improved, but leakage current increases causing accelerated discharge
Solution Approach 1:
A buffer circuit is introduced as an intermediary component between the battery cell voltage measurement path and the sensing circuit. The buffer circuit includes a transistor that isolates the measurement path from the system ground, preventing the formation of leakage current loops while maintaining voltage measurement capability. This mediator allows the system to benefit from precise voltage measurement without suffering from the harmful leakage current effect.
2Measurement precision
If a path for measuring battery cell voltage is implemented, then charging control precision is improved, but measurement accuracy deteriorates due to noise
Solution Approach 1:
The buffer circuit acts as an intermediary that isolates the high-impedance voltage measurement path from noise sources in the system. By placing the buffer between the measurement path and the sensing circuit, electromagnetic interference and noise from other system components are prevented from coupling into the sensitive voltage measurement, thereby maintaining measurement accuracy.
3Reliability
If the protection circuit opens the FET at over-charge cut-off voltage, then battery protection is achieved, but voltage measurement continues requiring additional measurement paths
Solution Approach 1:
The buffer circuit serves multiple functions simultaneously: it enables voltage measurement during normal operation, maintains measurement capability when the protection FET is open, and prevents leakage current. This multi-functional design eliminates the need for separate measurement paths for different operating conditions, reducing overall system complexity while maintaining reliability.
Data Source
AI summary
According to an embodiment, a battery pack comprises a battery cell including a positive electrode and a negative electrode and configured to generate an electromotive force via the positive electrode and the negative electrode, a plurality of first sub paths configured to connect the positive electrode to a sensing circuit of an electronic device to which the battery pack is connected, a plurality of second sub paths configured to connect the negative electrode to the sensing circuit, a power line configured to connect the positive electrode and the negative electrode to at least one of a system of the electronic device or a charging circuit of the electronic device, a first switch configured to selectively connect at least one of the plurality of first sub paths, selected depending on a voltage applied to the positive electrode and the negative electrode, to the sensing circuit, and a second switch configured to selectively connect at least one of the plurality of second sub paths, selected depending on the voltage, to the sensing circuit.