Equation-Based State Estimation for Fuel Cell Air Systems
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Solution Overview
Problem
There is a need for systems and methods to accurately and quickly provide air at a desirable rate and pressure to fuel cells in fuel cell vehicles, as the oxygen requirements and air pressure within the fuel cells vary based on the desired power output, which is variable and driven by power requests from drivers or electronic control units in autonomous vehicles.
Innovation Solution
A system comprising a compressor, fuel cell stack, pipes, pressure sensor, and electronic control unit (ECU) that estimates airflow and pressure values using a model of the fuel cell circuit, allowing for feedforward and feedback control of actuators to achieve desired pressure and airflow values, with a bypass branch and valve to adjust airflow and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple sensors are used to directly measure airflow and pressure at each component location, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces a mathematical model of the fuel cell circuit as an intermediary between the physical system and measurement. The model uses differential equations to represent the relationships between airflow, pressure, and component characteristics. By solving these equations with minimal sensor inputs, the system indirectly determines airflow and pressure at all locations without placing sensors everywhere, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent creates a virtual copy of the fuel cell circuit in the form of a mathematical model that replicates the physical system's behavior. This virtual model allows the system to estimate airflow and pressure values at any point in the circuit by solving the model equations, effectively copying the measurement capability without physical sensors at each location
2Stability of the object's composition
If traditional feedback control is used, then system stability is improved, but response speed to power requests deteriorates
Solution Approach 1:
The patent implements feedforward control by calculating desired airflow and pressure values in advance based on the power request and the mathematical model. The controller determines target values for airflow and pressure before the actual control action is needed, allowing the system to proactively adjust actuators rather than reactively responding to deviations, thus improving response speed while maintaining stability through the model-based prediction
Solution Approach 2:
The patent combines feedforward control with feedback mechanisms by using the mathematical model to predict system behavior and comparing predicted values with actual measurements from minimal sensors. This hybrid approach allows the system to maintain stability through continuous monitoring and correction while achieving fast response through the predictive feedforward component
3Measurement precision
If a detailed mathematical model of the entire fuel cell circuit is created, then estimation accuracy is improved, but calculation complexity and processing time increase
Solution Approach 1:
The patent divides the fuel cell circuit into discrete components (compressor, intercooler, fuel cell stack, pipes, bypass valve) and creates separate differential equations for each component's airflow and pressure characteristics. This segmentation allows the complex circuit to be modeled as a system of manageable component equations that can be solved efficiently, reducing overall computational complexity while maintaining estimation accuracy
Solution Approach 2:
The patent transforms the physical circuit parameters (component geometries, flow characteristics, pressure relationships) into mathematical model parameters that can be processed computationally. By changing the representation of physical parameters into standardized model parameters, the system achieves accurate estimation while optimizing calculation efficiency through parameter-based modeling rather than complex geometric or physical simulations
Data Source
AI summary
A system for providing oxygen to a fuel cell circuit includes a compressor and a fuel cell stack having a plurality of fuel cells. The system also includes a plurality of pipes and a pressure sensor designed to detect pressure at a first location. The system also includes a memory to store a model of the fuel cell circuit and an ECU. The ECU determines a control signal corresponding to desirable operation of the compressor and determines flow values of the gas through each component based on the detected pressure and the model of the fuel cell circuit. The ECU also determines pressure values of each component based on the determined flow values and the model of the fuel cell circuit. The ECU also controls operation of the compressor based on the control signal, at least one of the flow values, and at least one of the pressure values.