Non-Isolating Pre-Regulator for High-Temperature Fuel Cell Voltage Management
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Solution Overview
Problem
High temperature fuel cell systems face challenges in efficiently managing heat and reducing power electronics costs due to the need for high-voltage components that result in significant power losses and large system sizes, especially during start-up and low current load situations.
Innovation Solution
A non-isolating pre-regulator is used between the fuel cells and the main power converter to reduce fuel cell voltage to a usable level at low power levels, and is bypassed at high current loads, allowing for a more compact and cost-effective power electronics design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If high-voltage components are used in the main power converter, then the system can operate at higher fuel cell voltage values, but power losses increase and component size increases
Solution Approach 1:
The power conversion system is divided into two separate converters: a first power converter optimized for high-voltage operation during start-up and low-load conditions, and a second power converter optimized for lower-voltage operation during nominal conditions. This segmentation allows each converter to be sized and designed for its specific operating range, minimizing power losses in both regimes.
Solution Approach 2:
The system dynamically switches between the first and second power converters based on operating conditions. The control arrangement activates the first converter during start-up and low-load situations when high voltage is beneficial, and switches to the second converter during nominal operation to reduce power losses and component stress.
2Power
If high-voltage components are used in the main power converter, then the system can operate at higher fuel cell voltage values, but component size increases
Solution Approach 1:
The power conversion system is divided into two separate converters: a first power converter optimized for high-voltage operation during start-up and low-load conditions, and a second power converter optimized for lower-voltage operation during nominal conditions. This segmentation allows each converter to be sized and designed for its specific operating range, minimizing power losses in both regimes.
Solution Approach 2:
The system dynamically switches between the first and second power converters based on operating conditions. The control arrangement activates the first converter during start-up and low-load situations when high voltage is beneficial, and switches to the second converter during nominal operation to reduce power losses and component stress.
3Temperature
If electrical heaters are used for heat management, then temperature control is improved, but earth fault currents are generated
Solution Approach 1:
A non-isolating pre-regulator is introduced as an intermediary component between the fuel cell stack and the main power converter. This pre-regulator provides galvanic isolation, preventing earth fault currents from propagating through the system while still enabling effective temperature control of the fuel cell stack.
Solution Approach 2:
The patent replaces electrical heaters with a fuel bypass arrangement where unreacted fuel is recirculated back to the anode inlet. This mechanical/chemical heating method avoids generating earth fault currents while effectively managing stack temperature through the exothermic combustion of recirculated fuel.
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 minimizes power losses and reduces the size and cost of power electronics components, enabling more efficient heat management and compact system design by optimizing fuel cell operation at higher voltage values.
Implementation Method 1
A non-isolating pre-regulator is used between the fuel cells and the main power converter to reduce fuel cell voltage to a usable level
Implementation Method 2
Fuel cell devices are electrochemical devices supplied with reactants for producing electrical energy
Implementation Method 3
The extra thermal energy in circulating gas is recovered in the heat exchanger 105 to be utilized in SOFC device
Implementation Method 4
Reformer is a device that converts the fuel such as for example natural gas to a composition suitable for fuel cells
Data Source
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AI summary
The object of the invention is an arrangement for improved operability of a high temperature fuel cell device at higher fuel cell voltage values than nominal voltage values, each fuel cell (103) in the fuel cell device comprising an anode side (100), a cathode side (102), and an electrolyte (104) between the anode side and the cathode side, and the arrangement comprises means (132) for determining essential temperature information of the fuel cells (103) and main power converter (123) for loading fuels cells at least up to their rated power level. The arrangement comprises a non-isolating preregulator (122) for reducing the fuel cell voltage to a voltage level useable for the main power converter (123) at least at substantially low power levels in start-up and low current load situations when the fuel cell voltage is significantly higher than in nominal operation conditions, said pre-regulator (122) being located between the fuel cells (103) and the main power converter (123), and the arrangement comprises bypass means (408) for by- passing the pre-regulator (122) at substantially high current loads when the fuel cell voltage has decreased to the voltage level suitable for an input voltage of the main power converter.