Six-phase Transformer Rectifier Unit for Common Mode Voltage Cancellation

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Solution Overview

Problem

Current transformer rectifier units face challenges in reducing common mode voltage noise in dual-polarity direct current power supplies, often requiring heavy and costly common mode chokes to achieve desired noise reduction.

Innovation Solution

A transformer rectifier unit configuration that generates phase-shifted alternating currents, offset by one-twelfth of a cycle, to produce a direct current power supply with a common mode voltage reduced to zero, eliminating the need for common mode chokes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a common mode choke is used to reduce common mode voltage noise, then the noise in dual-polarity output voltage is reduced, but the weight and cost of the transformer rectifier unit increase

Engineering Contradiction:

Improvecommon mode voltage noiseVSAvoidweight of transformer rectifier unit

Core Design Contradiction:

Object-affected harmful factorsVSWeight of stationary object

Solution Approach 1:

The patent removes the common mode choke from the system by using a twelve-phase rectifier configuration that inherently cancels common mode voltage through phase-shifted alternating currents, eliminating the need for separate noise reduction components

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the electrical parameters by using twelve-phase rectification with specific phase shifts (one-twelfth of a cycle) to transform the common mode voltage characteristics, reducing it to zero through mathematical cancellation rather than physical filtering

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If a common mode choke is used to reduce common mode voltage noise, then the noise in dual-polarity output voltage is reduced, but the cost of the transformer rectifier unit increases

Engineering Contradiction:

Improvecommon mode voltage noiseVSAvoidcost of transformer rectifier unit

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The twelve-phase rectifier performs multiple functions simultaneously: it converts six-phase AC to DC while inherently canceling common mode voltage noise, eliminating the need for separate filtering components and reducing overall system complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If six-phase rectification is used without phase shifting, then the rectifier structure is simpler, but the common mode voltage noise increases

Engineering Contradiction:

Improverectifier structure complexityVSAvoidcommon mode voltage noise

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the phase angle parameter of the alternating currents by introducing one-twelfth of a cycle phase shift between the six input phases, which mathematically cancels common mode voltage while maintaining a relatively simple rectifier structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces asymmetric phase shifting patterns among the six-phase inputs, where specific phases are shifted by different amounts (one-twelfth of a cycle relative to others), creating an asymmetric configuration that achieves common mode cancellation

Inventive Principle:

Principle #4Asymmetry

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 effectively reduces undesired noise in the dual-polarity output voltage, improving the performance of electrical components and reducing the overall weight and cost of the transformer rectifier unit.

Implementation Method 1

The transformer is configured to output a plurality of phase-shifted alternating currents in response to receiving a plurality of alternating currents

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The rectifier is configured to form a direct current power supply having a common mode voltage reduced to zero within selected tolerances in response to receiving the plurality of input alternating currents

Methodology Applied

Scientific EffectRectification:

Data Source

PatentUS9793820B2Six-phase supplied transformer rectifier unit

Publication Date: 2017.10.17 THE BOEING CO

AI summary

A method and apparatus for forming a direct current power supply. An apparatus comprises a transformer and a rectifier. The transformer is figured to output a plurality of phase-shifted alternating currents in response to receiving a plurality of alternating currents. The plurality of alternating currents and the plurality of phase-shifted alternating currents form a plurality of input alternating currents that are offset relative to each other by one-twelfth of a cycle in phase. The rectifier is configured to form a direct current power supply having a common mode voltage reduced to zero within selected tolerances in response to receiving the plurality of input alternating currents.