Variable Frequency Power System for Hybrid Aircraft Propulsion

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current aircraft propulsion systems face inefficiencies and weight increases due to regenerative energy issues from electric actuators, requiring significant power electronics and fuel reserves, which are costly and limit mission capability.

Innovation Solution

A hybrid propulsion system utilizing a turbine engine, multiple electric machine assemblies, and a variable frequency power system with doubly fed electric machines to reduce power electronics weight and enhance energy management, allowing for high peak power and nominal power capability while minimizing collateral damage from faults.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If batteries and supercapacitors are used to recover regenerative energy, then energy can be reused as peaking power, but significant additional weight for power electronics is required

Engineering Contradiction:

Improveenergy recovery and reuseVSAvoidpower electronics weight

Core Design Contradiction:

Use of energy by moving objectVSWeight of moving object

Solution Approach 1:

The patent combines the generator and motor functions into a single doubly fed electric machine assembly, eliminating the need for separate power electronics for each function. This merging reduces the overall power electronics weight while maintaining energy recovery capability through the variable frequency power system that manages regenerative energy from electric actuators.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The doubly fed electric machine assembly serves multiple functions: it acts as a generator during propulsion, a motor during regenerative energy recovery, and interfaces with the variable frequency power system for energy management. This multi-functionality eliminates the need for dedicated power electronics for each operation, significantly reducing weight.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If clamping resistors are used to dissipate regenerative energy, then bus voltage can be controlled, but fuel reserves are required for cooling by emersion, limiting mission capability

Engineering Contradiction:

Improvebus voltage controlVSAvoidmission capability

Core Design Contradiction:

ReliabilityVSDuration of action of moving object

Solution Approach 1:

Instead of dissipating regenerative energy as heat through clamping resistors, the patent converts this harmful energy into useful electrical energy that can be stored and reused. The variable frequency power system captures regenerative energy from electric actuators and feeds it back to the battery or uses it for propulsion, eliminating the need for fuel-intensive cooling systems and extending mission capability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Productivity

If current propulsion systems improve engine efficiency by less than 1%, then performance increases slightly, but the cost to reach such improvement is substantial

Engineering Contradiction:

Improveengine efficiencyVSAvoidcost

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical propulsion systems with a hybrid electric system using doubly fed electric machine assemblies and variable frequency power conversion. This substitution enables more efficient energy management, regenerative braking, and optimized motor control, achieving substantial efficiency improvements (estimated 20-30% or more) rather than the marginal less than 1% improvement from conventional mechanical systems.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 system achieves an 85% reduction in power electronics weight, improved reliability, and reduced protection system weight by over 50%, enabling efficient energy storage and fault clearance without regenerative energy issues, thus enhancing aircraft performance and cost-effectiveness.

Implementation Method 1

a turbine engine, a first electric machine assembly connected to the turbine engine

Methodology Applied

Scientific EffectThermal energy conversion: Heat Engine

Implementation Method 2

a second electric machine assembly driven by the first electric machine assembly, and a plurality of third electric machine assemblies driven by the first electric machine assembly, wherein the plurality of third electric machines provide a thrust output

Methodology Applied

Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentUS10647439B1Variable frequency power system for hybrid electric aircraft propulsion

Publication Date: 2020.05.12 UNITED STATES GOVERNMENT ADMINISTRATOR OF NASA

AI summary

A hybrid propulsion system for an aircraft is provided that includes a turbine engine, a first electric machine assembly connected to the turbine engine, a second electric machine assembly driven by the first electric machine assembly, and multiple third electric machine assemblies driven by the first electric machine assembly, wherein the multiple third electric machines provide a thrust output to propel the aircraft.