Fuel Cell Power Distribution with Isolated DC Bus Bars
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Solution Overview
Problem
Power distribution assemblies with fuel cells face limitations due to low isolation resistance to ground, restricting power capacity to 1.5-2MW, necessitating expensive galvanic isolation for larger installations.
Innovation Solution
Implementing galvanic isolation between fuel cell groups by electrically connecting them to DC bus bars that are galvanically isolated from each other, enabling power transfer through multi-winding machine units, thereby eliminating the need for galvanically isolated DC/DC converters and reducing common mode noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If galvanic isolation is applied to increase power capacity beyond 2MW, then power capacity is improved, but system cost and component size increase
Solution Approach 1:
The system divides the fuel cell power distribution into multiple isolated DC bus bars (first DC bus bar, second DC bus bar, etc.), each serving separate fuel cell groups. This segmentation allows galvanic isolation between groups while maintaining overall system functionality, enabling power capacity expansion without requiring a single large isolated converter
Solution Approach 2:
Multi-winding machine units serve as intermediary devices between isolated DC bus bars, enabling power transfer between galvanically isolated groups through magnetic coupling. This intermediary approach achieves galvanic isolation without requiring expensive isolated DC/DC converters, as the machine units naturally provide isolation through their winding structure
2Power
If galvanic isolation is implemented, then power capacity is increased, but system efficiency decreases due to larger converters
Solution Approach 1:
The multi-winding machine units perform multiple functions: they act as motors/generators for propulsion and simultaneously serve as power transfer devices between isolated DC bus bars. This eliminates the need for separate isolated DC/DC converters, reducing system losses and improving overall efficiency while maintaining galvanic isolation
3Power
If a large DC bus bar is used, then power capacity is increased, but common mode noise and ground leakage currents increase
Solution Approach 1:
The system divides one large DC bus bar into multiple smaller isolated DC bus bars (first DC bus bar, second DC bus bar, etc.), each with its own isolated ground reference. This segmentation reduces the ground leakage capacitance and common mode noise of each individual bus bar, as the harmful effects are distributed and isolated rather than concentrated in a single large bus bar
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 allows for increased power capacity beyond 2MW without the need for expensive galvanic isolation, reduces ground leakage currents, and enhances system efficiency by eliminating the requirement for larger, less efficient galvanically isolating converters.
Implementation Method 1
enabling power transfer between different DC bus bars through at least one multi-winding machine unit
Data Source
Figure 1
Figure 2
AI summary
A power distribution assembly comprising: a first DC power source (21) and a second DC power source (22) each comprising at least one fuel cell; a first DC bus bar (41) electrically connected to the first DC power source (21), and a second DC bus bar (42) electrically connected to the second DC power source (22) and galvanically isolated from it; and a first supply converter (61) electrically connected to the first DC bus bar (41), and a second supply converter (62) electrically connected to the second DC bus bar (42). The power distribution assembly comprises at least one multi-winding machine unit (8), which is an alternating current rotating machine unit comprising a first stator winding and a second stator winding, wherein the first stator winding is electrically connected to the first supply converter (61), and the second stator winding is electrically connected to the second supply converter (62).