Fuel Cell Stack Start Control With Supercapacitor Voltage Gating

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Solution Overview

Problem

Fuel cell vehicles using supercapacitors as energy storage devices face challenges in starting stability due to direct connection without a DC/DC converter, leading to potential damage from low voltage and high instantaneous current.

Innovation Solution

A fuel cell vehicle power system with a controller that determines and controls the starting of the fuel cell stack based on the supercapacitor voltage, using a main relay and precharge relay to manage power transfer and prevent damage, eliminating the need for a separate DC/DC converter.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the fuel cell stack and supercapacitor are directly connected without a DC/DC converter, then the power system complexity is reduced, but the reliability of the fuel cell stack and relay is compromised due to low voltage damage and high instantaneous current risks

Engineering Contradiction:

Improvepower system complexityVSAvoidfuel cell stack reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The controller performs preliminary determination of voltage conditions before enabling fuel cell stack starting. The system checks whether the supercapacitor voltage meets the required threshold (e.g., 20V) before allowing the main relay to connect the fuel cell stack to the DC link, preventing damage from low voltage conditions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller continuously monitors the voltage of the supercapacitor and provides feedback control. Based on the real-time voltage measurement, the controller dynamically controls the main relay switching state, enabling or disabling fuel cell stack starting operations to maintain system reliability while allowing direct connection architecture

Inventive Principle:

Principle #23Feedback

2Device complexity

If the fuel cell stack and supercapacitor are directly connected without a DC/DC converter, then the device complexity is reduced, but harmful factors increase due to potential relay damage and fusion from high instantaneous current

Engineering Contradiction:

Improvedevice complexityVSAvoidrelay damage risk

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The controller implements preliminary protective action by determining voltage conditions before relay activation. When the supercapacitor voltage is insufficient, the controller prevents main relay closure, thereby preemptively avoiding the high instantaneous current that would cause relay damage or fusion

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The controller acts as an intermediary between the supercapacitor and fuel cell stack connection. It mediates the direct connection by intelligently controlling the main relay switching based on voltage conditions, protecting the relay from harmful high current while maintaining the simplified direct connection architecture

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20240174133A1Fuel cell vehicle and method of controlling the same

Publication Date: 2024.05.30 HYUNDAI MOTOR CO LTD

AI summary

A fuel cell vehicle includes a fuel cell stack connected to a direct current (DC) link, an energy storage device selectively connected to the DC link through a main relay, and a controller configured to determine whether or not starting of the fuel cell stack is allowed according to a voltage of the energy storage device, and to control starting of the fuel cell stack based on a result of the determination.