Fuel Cell Vehicle Power Control for Regenerative Braking Capacity
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Solution Overview
Problem
Fuel cell vehicles face challenges in matching instantaneous driver demand power due to non-dynamic voltage and current output, leading to inefficiencies in power storage and regeneration during braking, as the electric energy storage device may not always have capacity to store charge from the fuel cell.
Innovation Solution
A vehicle operating method that anticipates reductions in driver demand power by adjusting fuel cell output and increasing electric power consumption from the energy storage device, using a controller to reduce fuel and air supply to the fuel cell before actual demand reduction, allowing regenerative braking to store more energy and meet driver demands effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If fuel cell output power is commanded to simply follow driver demand power, then vehicle performance may meet driver demand during some conditions, but voltage and current output from the fuel cell cannot change instantaneously and may not change as dynamically as driver demand power changes
Solution Approach 1:
The controller anticipates future driver demand power changes based on current demand and driving patterns, adjusting fuel cell output power in advance before the actual demand change occurs. This preliminary action allows the fuel cell to respond more dynamically to driver demands without waiting for instantaneous changes.
Solution Approach 2:
The system dynamically adjusts fuel cell output power by combining real-time driver demand with anticipated future demand. The controller continuously modifies the fuel cell operating point based on changing conditions, enabling the fuel cell to adapt its output dynamically rather than following a static command signal.
2Power
If fuel cell output power is increased to meet driver demand, then driver demand power may be met, but electric energy storage device may not always have capacity to store charge from the fuel cell
Solution Approach 1:
The controller anticipates reductions in driver demand power and reduces fuel cell output power in advance. This prevents excessive charge from being generated that would exceed the energy storage device's capacity, allowing regenerative braking energy to be stored effectively without being overwhelmed by fuel cell charge.
Solution Approach 2:
The system continuously monitors the state of charge of the energy storage device and adjusts fuel cell output accordingly. When the energy storage device approaches full capacity, the controller reduces fuel cell output to prevent overcharging, creating a feedback loop that balances power generation with storage capacity.
3Quantity of substance
If fuel cell output power is reduced to match driver demand, then energy storage capacity is preserved, but driver demand power may not be met during quick increases
Solution Approach 1:
The controller anticipates increases in driver demand power and increases fuel cell output power in advance. This ensures that when driver demand quickly increases, the fuel cell is already producing the necessary power to meet the demand without depleting energy storage capacity.
4Loss of energy
If regenerative braking is used to store energy, then energy recovery is improved, but fuel cell and electric machine must simultaneously store charge which may not be possible
Solution Approach 1:
The controller anticipates regenerative braking events and reduces fuel cell output power before braking occurs. This preliminary reduction prevents the fuel cell from generating charge that would conflict with regenerative braking charge, eliminating the need for simultaneous storage and maximizing energy recovery capability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances regenerative power storage, ensures driver demand power is met by reducing fuel cell output before actual reductions, and improves fuel efficiency by anticipating changes in driver demand, allowing for better power management between the fuel cell and energy storage device.
Implementation Method 1
A fuel cell of a vehicle may convert fuel into electric power and the electric power may be applied to propel the vehicle. The fuel cell may split a H2 molecule into to H+ ions and two free electrons.
Data Source
AI summary
Methods and systems are described for controlling output of a fuel cell that generates electrical power for an electric machine that propels a vehicle. In one example, a driver demand power reduction is anticipated and output of the fuel cell is adjusted before the driver demand power is reduced so that a greater amount of electric charge may be stored in an electric energy storage device.