Dual-Input Nine-Phase Autotransformer Harmonic Reduction
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Solution Overview
Problem
Existing autotransformers in AC-DC power conversion systems generate substantial current harmonics, which pollute the electric power generation and distribution system, and increasing the number of AC phases helps reduce harmonics but requires complex configurations.
Innovation Solution
A dual-input nine-phase autotransformer is designed to convert two three-phase AC inputs into a nine-phase AC output with a 40° phase shift, using multiple coils wound on phase legs and internal connections to minimize harmonics and provide both step-up and step-down voltage functionality in a single, symmetrical configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard dual-winding transformer is used, then electrical isolation and safety are improved, but weight and size increase
Solution Approach 1:
The patent merges the primary and secondary windings into a single autotransformer winding structure, where a portion of the winding serves both as primary and secondary. This consolidation eliminates the need for electrically isolated dual windings while reducing overall transformer weight and size, directly addressing the contradiction between electrical isolation requirements and weight reduction goals.
Solution Approach 2:
The autotransformer winding performs multiple functions simultaneously: it provides voltage transformation, current conduction, and partial electrical isolation through its tapped structure. The single winding structure serves both as primary and secondary winding, achieving multi-functionality that reduces component count and weight while maintaining necessary electrical properties.
2Device complexity
If a three-phase AC input is used, then system simplicity is improved, but current harmonics increase
Solution Approach 1:
The patent segments the single autotransformer winding into multiple sections with different tap points, creating nine distinct voltage outputs from a three-phase input. This segmentation of the winding structure transforms the harmonic-rich three-phase input into a nine-phase output with reduced harmonics, while maintaining relative system simplicity.
Solution Approach 2:
The patent transitions from a three-dimensional three-phase system to a nine-dimensional nine-phase system by creating nine output phases from the three input phases. This dimensional expansion in the electrical phase domain effectively reduces current harmonics while maintaining input system simplicity.
3Object-generated harmful factors
If an eighteen-pulse converter is used, then current harmonics are reduced, but the number of AC phases and system complexity increase
Solution Approach 1:
The patent combines the functions of multiple separate transformers and windings into a single integrated autotransformer structure that directly produces nine-phase outputs. This merging achieves the harmonic reduction effect of an eighteen-pulse converter while avoiding the complexity of multiple separate phases and windings, effectively combining simplicity with harmonic mitigation.
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 dual-input nine-phase autotransformer effectively reduces current harmonics by generating a 40° phase-shifted nine-phase AC output, enabling efficient AC-DC conversion while minimizing the apparent power kVA rating and allowing for both step-up and step-down voltage operations in a compact, symmetrical design.
Implementation Method 1
The autotransformer includes a first plurality of coils A0-A6 wound on a first phase leg of the autotransformer, a second plurality of coils B0-B6 wound on a second phase leg of the autotransformer, and a third plurality of coils C0-C6 wound on a third phase leg of the autotransformer
Data Source
AI summary
A dual-input nine-phase autotransformer converts first and second three-phase AC inputs to a nine-phase AC output. The autotransformer includes input terminals for connection to a first three-phase AC input and a second three-phase AC input smaller than the first three-phase AC input. The autotransformer includes a first plurality of coils, a second plurality, and a third plurality of coils wound on respective phase legs of the autotransformer. The autotransformer includes a plurality of output terminals for providing a plurality of AC output voltages, and a plurality of internal terminals for connecting the first, second, and third plurality of coils in a configuration that provides a 40° phase shift in the AC outputs provided by the dual-input nine-phase autotransformer.