Switch-Mode Battery Circuit for Fuel Cell Traction Power
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Solution Overview
Problem
Current fuel cell systems for electric vehicles are limited by low power density, high cost, and weight sensitivity, particularly in high-reliability applications like aviation, due to the need for large numbers of low-voltage fuel cells and the use of inefficient DC-DC converters to achieve high voltage, which adds mass and complexity.
Innovation Solution
A novel energy storage and power delivery system that combines a low-voltage fuel cell stack with a switch-mode battery system, eliminating the need for DC-DC converters by using reconfigurable battery circuits to provide high voltage directly to the traction motor, enhancing safety, reducing mass, and adding redundancy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If DC-DC converters are used to convert low-voltage fuel cell output to high voltage for traction motors, then voltage compatibility is achieved, but system mass and complexity increase
Solution Approach 1:
The patent combines the fuel cell stack with battery circuits to form a hybrid energy storage system where the battery serves dual purposes: energy storage and voltage transformation. The battery is electrically connected between the fuel cell and traction motor, eliminating the need for separate DC-DC converters by merging voltage conversion function into the battery system itself.
Solution Approach 2:
The battery in the hybrid system performs multiple functions: it stores energy, provides voltage step-up transformation from low-voltage fuel cell output to high voltage required by traction motors, and supplies power during peak demand. This multi-functionality eliminates the need for dedicated DC-DC conversion equipment.
2Stress or pressure
If DC-DC converters are used to achieve high voltage from low-voltage fuel cells, then voltage compatibility is achieved, but parasitic losses increase
Solution Approach 1:
The patent merges the voltage transformation function into the battery system itself. The battery acts as both energy storage device and voltage transformer, eliminating the need for separate DC-DC converters that would introduce parasitic losses from additional power electronics and conversion inefficiencies.
3Stress or pressure
If large numbers of low-voltage fuel cells are connected in series to achieve high voltage, then voltage requirement is met, but system mass and cost increase
Solution Approach 1:
The patent combines a low-voltage fuel cell stack with battery circuits in a hybrid configuration. The battery bridges the voltage gap between the low-voltage fuel cell (60-120V) and the high-voltage traction motor requirement, eliminating the need to connect numerous fuel cells in series, thereby reducing system mass and complexity.
4Reliability
If redundant energy storage systems are implemented for high reliability applications, then system reliability improves, but device complexity increases
Solution Approach 1:
The patent implements a hybrid energy storage system combining fuel cell and battery that provides inherent redundancy. The battery can operate independently to power the traction motor if the fuel cell fails, and the fuel cell can recharge the battery. This merged system provides reliability benefits while managing complexity through integrated control.
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 solution improves reliability, reduces weight and cost, and increases efficiency by eliminating parasitic losses associated with DC-DC converters, while providing continuous power and redundancy critical for high-reliability applications like aircraft, where system failure can be catastrophic.
Implementation Method 1
Fuel cells convert chemical potential energy in the form of hydrogen and oxygen directly into electrical energy
Implementation Method 2
A secondary battery is a device consisting of one or more electrochemical or electrostatic cells that can be charged electrically to provide a static potential for power or released electrical charge when needed
Data Source
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AI summary
Combination fuel cell stack and electrochemical battery system provides stable and redundant electrical power to one or more traction motors. The electrochemical battery packs comprise modules that are switched between a low-voltage parallel configuration connecting to the fuel cell stack and a high-voltage series configuration connecting to the traction motors, thereby harvesting low-voltage energy from the fuel cells and deploying that energy as high-voltage power to the motor. The plurality of electrochemical battery packs can be switched such that at least one is always connected to the traction motor for continuity of power.