Impedance Measurement in Laminated Batteries via Phase Synchronization
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Solution Overview
Problem
Impedance measurement accuracy in laminated type batteries, such as fuel cell batteries, is compromised due to capacitance variations causing phase differences between alternating-current potential differences on positive and negative electrode sides, leading to current leakage and unreliable measurement results.
Innovation Solution
An impedance measuring device with separate power supply units for positive and negative electrodes, detection units for potential differences, and an adjustment unit to synchronize alternating currents, along with a computation unit to calculate impedance and diagnose measurement reliability based on phase differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If alternating current is output to both positive and negative electrode terminals for impedance measurement, then impedance measurement can be performed, but current leaks to the load side when capacitance components cause phase difference between electrode sides
Solution Approach 1:
The patent implements feedback control by detecting the potential difference between positive and negative electrode terminals and adjusting the alternating current output to eliminate this potential difference. This feedback mechanism ensures that no current leaks to the load side during impedance measurement, thereby maintaining both measurement precision and reliability even when capacitance components cause phase differences.
Solution Approach 2:
The patent applies the equipotentiality principle by actively controlling the potential difference between positive and negative electrode terminals to be zero during impedance measurement. By adjusting the alternating current output based on detected potential differences, the system maintains equipotential conditions at the terminals, preventing current leakage to the load while enabling accurate impedance measurement.
2Reliability
If phase difference detection and measurement state diagnosis are added to detect defective measurement states, then measurement reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies multi-functionality by enabling the existing potential difference detection unit to serve dual purposes: both controlling the alternating current output to maintain equipotential conditions and detecting phase differences for measurement state diagnosis. This approach improves measurement reliability without adding separate dedicated detection devices, thereby limiting the increase in device complexity.
Data Source
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AI summary
An impedance measuring device outputs an alternating current of a prescribed frequency to a positive electrode terminal and a negative electrode terminal of the laminated type battery. The impedance measuring device detects an alternating-current potential difference between the positive electrode terminal and an intermediate-point terminal, and an alternating-current potential difference between the negative electrode terminal and the intermediate-point terminal. The impedance measuring device adjusts an amplitude of the alternating current such that the alternating-current potential difference between the positive electrode terminal and the intermediate-point terminal, and the alternating-current potential difference between the negative electrode terminal and the intermediate-point terminal coincide. The impedance measuring device computes an impedance of the laminated type battery on the basis of the alternating current adjusted and the alternating-current potential difference. On the a phase difference between an alternating-current potential generated at the positive electrode terminal and an alternating-current potential generated at the negative electrode terminal, or a parameter related to the phase difference, the impedance measuring device performs any one process of: a diagnosis process for diagnosing whether or not a measurement state is defective; a cancellation process for discarding a measurement result; and a hold process for fixing the measurement result at a prescribed value.