Harmonic Filtering in Marine Electrical Systems
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Solution Overview
Problem
Existing multiple phase electrical systems with rectified AC power suffer from significant 5th and 7th order harmonic currents, leading to overrating of electrical equipment and inefficiencies, particularly in marine and aerospace applications.
Innovation Solution
A dual lane electrical system with a transformer having power and phase shift windings, where the phase shift windings are serially connected to form an autotransformer, and an embedded RLC filter tuned to the 12th harmonic frequency to cancel 5th and 7th harmonic currents, reducing the need for a tertiary winding and minimizing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a dual lane twelve pulse power supply with YD transformers is used to reduce 5th and 7th harmonics, then harmonic content is reduced, but device complexity and material usage increase due to requiring two fully rated three winding transformers
Solution Approach 1:
The patent merges the functions of two separate three-winding transformers into a single two-winding YD transformer with an embedded tertiary winding. This consolidation reduces the number of discrete transformer units while maintaining the harmonic filtering capability through the integrated tertiary winding that provides a circulation path for 5th and 7th harmonic currents.
Solution Approach 2:
The patent implements a nested structure by embedding the tertiary winding (with N3 turns) within the two-winding YD transformer configuration. The tertiary winding is nested between the primary and secondary windings, creating a compact integrated design that provides harmonic filtering functionality without requiring separate external filter components.
2Object-generated harmful factors
If two fully rated three winding transformers are used to filter harmonics, then 5th and 7th harmonic currents are reduced, but weight and material usage increase
Solution Approach 1:
The patent combines the functionality of two heavy three-winding transformers into a single integrated two-winding YD transformer with an embedded tertiary winding. This merger significantly reduces the total transformer weight and material usage while maintaining effective harmonic current filtering through the circulation path provided by the embedded tertiary winding.
3Device complexity
If a YD transformer with embedded tertiary winding is used, then device complexity is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The embedded tertiary winding configuration requires precise nesting of three windings (primary, secondary, and tertiary) within a single transformer core. The tertiary winding with N3 turns must be precisely positioned and connected to create the correct circulation path for harmonic currents, increasing manufacturing precision requirements despite reducing overall device complexity.
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 cancels 5th and 7th harmonic currents, reducing total harmonic distortion in generators from 26.6% to 4.5%, allowing for lighter and less expensive transformer designs while maintaining efficient power delivery.
Implementation Method 1
an embedded RLC filter tuned to the 12th harmonic frequency to cancel 5th and 7th harmonic currents
Implementation Method 2
a transformer connected between the two lanes, the transformer having a plurality of power windings across which corresponding phases of the first and second lanes are connected, and a plurality of phase shift windings
Data Source
Figure 1~2
Figure 3~5
Figure 4~6
AI summary
This invention relates to a multiple phase electrical system (310), comprising: a first and a second electrical lane (312,314) each lane having a generator (316a,316b) and a load (324) connected by a bus system (326a,326b), and a rectifier (320a,320b) between the generator and load; and, a transformer (318) connected between the two lanes, the transformer having a plurality of power windings (330a-c) across each of which corresponding phases of the first and second lanes are connected, and a plurality of phase shift windings (332a-c). The transformer provides a path for the circulation of the dominant 5th and 7th harmonic currents generated by each rectifier and prevents these undesirable currents from flowing in each of the generators.