eVTOL Rotor Locking via Inverter Circulatory Current

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Solution Overview

Problem

Current electric motor systems in eVTOL aircraft lack an efficient method to lock rotors at desired positions without relying on mechanical locks or complex dynamic controls, which can add weight and energy consumption.

Innovation Solution

Implementing an electronic lock within the power inverter of the motor system by selectively closing switches to create a circulatory current flow path, generating an opposing force to hold the rotor in place, eliminating the need for mechanical locks and reducing energy usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical locks are used to lock the rotor at a desired position, then the rotor can be securely held in place, but the system weight increases and structural complexity increases

Engineering Contradiction:

Improverotor position holdingVSAvoidsystem weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces mechanical locking mechanisms with an electronic braking system that uses the power inverter's switching devices to generate opposing electromagnetic forces. The control circuit closes specific switches to create current flow paths that produce braking torque, eliminating the need for mechanical locks and reducing system weight while maintaining rotor position holding capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The power inverter is designed to perform multiple functions: normal motor operation and electronic rotor locking. By utilizing the existing switching devices and control circuitry of the power inverter, the system achieves rotor position holding without requiring dedicated mechanical locking components, thereby reducing overall system complexity and weight.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If mechanical locks are used to lock the rotor, then the rotor can be held at a desired position, but the device complexity increases

Engineering Contradiction:

Improverotor position holdingVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent replaces mechanical locking mechanisms with an electronic braking system that uses the power inverter's switching devices to generate opposing electromagnetic forces. This substitution eliminates the need for mechanical locks, reducing structural complexity while maintaining locking reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If complex dynamic control is used to maintain rotor position, then the rotor can be held at the desired position, but energy consumption increases

Engineering Contradiction:

Improverotor position holdingVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The electronic locking mechanism uses periodic switching of the inverter's semiconductor devices to maintain the braking effect. By switching the devices on and off in a controlled manner, the system maintains rotor position with minimal average power consumption, as the opposing electromagnetic force is applied only when needed to counteract external disturbances.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent replaces mechanical locking mechanisms with an electronic braking system that uses the power inverter's switching devices to generate opposing electromagnetic forces. This electronic approach reduces energy consumption compared to continuous mechanical engagement while maintaining effective rotor position holding.

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

This solution allows for efficient and weight-reduced rotor locking, enhancing flight control by aligning rotors for reduced drag and minimizing energy consumption, while avoiding the need for additional mechanical components.

Implementation Method 1

the current flowing in the circulatory current flow path within the power inverter will generate an opposing force to oppose the movement of the rotor

Methodology Applied

Scientific EffectElectromagnetic force: Lorentz Force

Data Source

PatentUS20250015734A1eROTOR LOCK FOR eVTOL LIFTERS

Publication Date: 2025.01.09 HAMILTON SUNDSTRAND CORP

AI summary

An electronic rotor “lock” that can be implemented within an electric motor system by selecting closing a subset of switches within an inverter of the motor drive system to create a circulatory current path that can generate a force that acts to oppose any external movement of the rotor.