Fuel Cell Startup Voltage Control in Work Vehicle Converters
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Solution Overview
Problem
Fuel cells output a significantly higher voltage than the rated output voltage during startup, necessitating a higher withstand voltage for connected devices like converters, which can be inefficient and costly.
Innovation Solution
A work vehicle configuration that includes a fuel cell, a converter, a chopper circuit, a contactor, and a control device to manage voltage fluctuations during startup, allowing the converter to operate within its rated voltage without exceeding its withstand voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the withstand voltage of the converter is set to be equal to or higher than the voltage during fuel cell startup, then the converter can withstand the startup voltage, but the converter cannot operate efficiently and the cost increases
Solution Approach 1:
A chopper circuit is introduced as an intermediary device between the fuel cell and the converter. The chopper circuit controls the voltage transmission from the fuel cell, ensuring that the converter receives voltage within its rated range during both startup and normal operation, thereby protecting the converter without requiring it to have high withstand voltage capability
Solution Approach 2:
The chopper circuit dynamically changes the voltage parameter transmitted to the converter by controlling the switching timing and duty cycle. During fuel cell startup when voltage is high, the chopper circuit limits the transmitted voltage to the converter's rated level, allowing the converter to operate efficiently without needing to withstand high startup voltages
2Reliability
If the withstand voltage of the converter is set to be equal to or higher than the voltage during fuel cell startup, then the converter can withstand the startup voltage, but the cost of the converter increases
Solution Approach 1:
The chopper circuit serves as a protective intermediary that prevents high startup voltage from reaching the converter. This allows the converter to be manufactured with lower withstand voltage specifications, reducing its cost while still ensuring reliable operation during fuel cell startup
Solution Approach 2:
The chopper circuit provides beforehand protection by controlling voltage transmission before high startup voltage can damage the converter. By preemptively limiting voltage during startup, the system allows use of lower-cost converters that would otherwise be vulnerable to startup voltage spikes
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 effectively suppresses voltage fluctuations during fuel cell startup, allowing the converter to operate efficiently within its rated voltage, reducing the need for higher withstand voltages and associated costs.
Implementation Method 1
a chopper circuit provided between the fuel cell and the converter; a control device configured to control the chopper circuit and the contactor
Data Source
AI summary
A work vehicle includes a step-down circuit provided between a fuel cell and a converter, a contactor provided in parallel with the step-down circuit and configured to switch conduction and insulation between the fuel cell and the converter and a control device configured to control the step-down circuit and the contactor.