Fuel Cell Compressor Control via Limitative Pressure
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Solution Overview
Problem
Fuel cell systems experience noise issues due to periodic changes in compressor rotation speed caused by pulsation of cathode gas pressure, which is triggered by pulsation of anode gas pressure, leading to excessive stress on electrolyte membranes and potential deterioration.
Innovation Solution
A fuel cell system with a compressor control mechanism that sets a limitative target pressure by limiting pulsation of the cathode gas pressure and controlling the compressor based on this pressure, along with maintaining an allowable inter-membrane pressure difference, to suppress noise generation and ensure membrane protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lower limit pressure for membrane protection is set as the target pressure of the cathode gas, then the inter-membrane pressure difference is maintained within allowable limits, but the compressor rotation speed periodically changes in response to pulsation of the target pressure, generating noise
Solution Approach 1:
A limitative pressure calculation unit is introduced as an intermediary component between the target pressure setting and compressor control. This unit calculates a limitative pressure by subtracting a predetermined allowable pressure fluctuation range from the target pressure, thereby mediating the relationship between membrane protection requirements and compressor stability. The compressor control unit then uses this limitative pressure instead of the raw target pressure, preventing direct transmission of pressure pulsations to the compressor while maintaining membrane protection through the relief valve control.
2Productivity
If the compressor is controlled on the basis of the target pressure and target flow rate, then the cathode gas supply is optimized for fuel cell performance, but the rotation speed of the compressor periodically changes in response to pulsation of the target pressure
Solution Approach 1:
The limitative pressure calculation unit serves as an intermediary that processes the target pressure before it reaches the compressor control unit. By calculating a stabilized limitative pressure value that excludes pulsation components, this intermediary enables the compressor to maintain stable rotation speed while the fuel cell continues to receive optimized gas supply through the relief valve's pressure regulation function.
3Adaptability or versatility
If pulsation operation is performed on the anode gas pressure, then gas distribution is improved, but the inter-membrane pressure difference varies in response to pulsation, potentially applying excessive stress to the electrolyte membrane
Solution Approach 1:
The system applies preliminary anti-action by proactively compensating for the harmful effects of anode gas pressure pulsation before they reach the electrolyte membrane. The control unit calculates the lower limit pressure for membrane protection by subtracting the allowable pressure difference from the pulsating anode pressure, and uses this calculated value to control the relief valve. This preliminary compensation ensures that even when anode pressure pulsates to improve gas distribution, the cathode pressure is adjusted in advance to prevent excessive stress on the membrane.
Data Source
AI summary
A fuel cell system includes a compressor, a relief valve that adjusts a pressure of a cathode gas, a pulsation operation unit that pulsates an anode gas pressure, a target flow rate setting unit that sets a target flow rate of the cathode gas, a first target pressure setting unit that sets a first target pressure of the cathode gas, a second target pressure setting unit that sets a second target pressure of the cathode gas for maintaining a pressure difference between an anode and a cathode within a predetermined allowable range, a target pressure setting unit that sets the higher one of the first and second target pressures as a target pressure, and a control unit that controls the compressor on the basis of the target flow rate and a limitative pressure obtained by limiting pulsation of the target pressure.