Fuel Cell Stack Current Control for Battery SOC and Coolant Stability

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Solution Overview

Problem

Fuel cell systems face performance degradation due to frequent variations in stack current, which can lead to inadequate environment conditions, potentially causing damage and requiring time-consuming adjustments, resulting in decreased performance.

Innovation Solution

A stack current controller determines the stack current request based on the battery's state of charge and coolant temperature, using specific thresholds and debounce ranges to stabilize current levels and avoid resonance, thereby maintaining optimal operating conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the stack current is frequently varied to meet different battery state of charge requirements, then the battery charging flexibility is improved, but the fuel cell environment stability deteriorates causing damage and performance degradation

Engineering Contradiction:

Improvebattery charging flexibilityVSAvoidfuel cell environment stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements dynamic stack current adjustment based on battery state of charge thresholds. The controller dynamically modifies stack current requests within a range (e.g., 50-150 amps) depending on whether the battery SOC is above or below the threshold, allowing flexible charging adaptation while maintaining fuel cell environmental stability through controlled variation ranges rather than abrupt changes

Inventive Principle:

Principle #15Dynamics

2Reliability

If the stack current is frequently adjusted to maintain battery charge levels, then the battery state of charge maintenance is improved, but the fuel cell system performance deteriorates due to time-consuming re-adjustments

Engineering Contradiction:

Improvebattery charge level maintenanceVSAvoidfuel cell system performance

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent employs periodic monitoring of battery state of charge against predefined thresholds, triggering stack current adjustments only when thresholds are crossed. This periodic action based on SOC thresholds (e.g., 50% threshold) maintains battery charge levels while minimizing the frequency of fuel cell re-adjustments, thereby preserving system performance

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If the stack current varies frequently to meet changing battery requirements, then the battery charging adaptability is improved, but the system component life deteriorates due to frequent adjustments

Engineering Contradiction:

Improvebattery charging adaptabilityVSAvoidsystem component life

Core Design Contradiction:

Adaptability or versatilityVSDuration of action of stationary object

Solution Approach 1:

The system dynamically adjusts stack current within controlled ranges based on battery SOC thresholds rather than making frequent abrupt changes. By implementing smooth transitions and limiting current variation幅度, the patent extends system component life while maintaining charging adaptability

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes operational parameters (stack current magnitude) based on battery state of charge conditions. By modifying current requests within specific ranges (e.g., reducing from 150 to 50 amps when SOC exceeds threshold) and using debounce ranges to prevent oscillation, the system extends component life while maintaining adaptability

Inventive Principle:

Principle #35Parameter changes

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

The solution stabilizes the stack current levels, reduces noise, and enhances the overall life of system components by maintaining consistent operating conditions, improving fuel cell performance and reducing the need for frequent adjustments.

Implementation Method 1

A fuel cell generates electrical power by converting chemical energy of a fuel into electrical energy by way of an electrochemical reaction

Methodology Applied

Scientific EffectElectrochemical reaction:

Implementation Method 2

Fuel cells typically utilize hydrogen as a fuel and oxygen (usually from air) as an oxidant in the electrochemical reaction

Methodology Applied

Scientific EffectElectrochemical conversion:

Implementation Method 3

The electrochemical reaction results in electricity, by-product water, and by-product heat

Methodology Applied

Scientific EffectElectrochemical reaction:

Data Source

PatentUS11990656B2System and methods for determining a stack current request based on fuel cell operational conditions

Publication Date: 2024.05.21 HYSTER YALE MATERIALS HANDLING INC

AI summary

A stack current controller may be configured to determine a stack current request based on a state of charge of a battery, an error based on a difference between an actual coolant temperature and a coolant temperature setpoint, or both. A plurality of stack current levels may be implemented corresponding to different battery state-of-charge thresholds. The determined stack current magnitude may be the lowest current magnitude that provides sufficient heat to maintain a coolant temperature at the coolant temperature setpoint or within the coolant temperature threshold. The determined stack current magnitude may be the highest current magnitude that provides sufficient power while maintaining a coolant temperature at the coolant temperature setpoint or within the coolant temperature threshold.