Fuel Cell Impedance Measurement via Multiphase Sampling
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Solution Overview
Problem
Current fuel cell systems face limitations in impedance measurement performance due to restricted sampling frequencies, which affect the optimal management of moisture levels and subsequently the efficiency of the fuel cell operation.
Innovation Solution
A fuel cell system equipped with a multiphase voltage conversion device, where control signals with a predetermined phase difference are used to sample current and voltage at multiple frequencies, allowing for detailed impedance calculation and improved measurement performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of sampling times is increased to improve impedance measurement performance, then measurement precision is improved, but CPU load increases
Solution Approach 1:
The patent divides the impedance measurement process into N phases, where each phase performs sampling at a specific sampling frequency. The control signal generation portion generates control signals for N phases sequentially with predetermined phase differences, and the impedance calculation portion calculates impedance based on sampling results from each phase. This segmentation allows distribution of sampling tasks across multiple phases, improving measurement precision while managing CPU load through structured phase-based processing.
2Measurement precision
If multiple sampling frequencies are used to improve measurement detail, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent employs periodic action by performing impedance measurement through N phases that are sequentially executed with predetermined phase differences. Each phase conducts sampling at its designated sampling frequency, and the process repeats periodically. This periodic multi-phase approach enables detailed impedance measurement using multiple sampling frequencies while maintaining systematic control through regular phase-based operation, avoiding chaotic complexity.
Data Source
AI summary
A fuel cell system includes a fuel cell, a multiphase voltage conversion device with N-phases (N being an integer equal to or larger than two) that is connected to the fuel cell, a control signal generation portion that generates control signals to control each phase of the multiphase voltage conversion device by superimposing a control waveform for measuring impedance on a voltage indicating an output target voltage of the multiphase voltage conversion device and sequentially outputs the control signals corresponding to N phases with a predetermined phase difference to the multiphase voltage conversion device, and an impedance calculation portion that measures a current and a voltage of the fuel cell on cycles corresponding to N predetermined sampling frequencies having a phase difference equal to the predetermined phase difference and calculates an impedance of the fuel cell based on the measured current and the measured voltage.