Multi-Motor Propulsion Speed Balancing Without Motor Communication

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Solution Overview

Problem

In electric or hybrid aircraft propulsion systems, the disparity in power supplied by multiple electric motors can lead to significant heating and potential breakdown of the motor providing the highest power, due to the lack of natural balancing and complex communication requirements between motors.

Innovation Solution

A balancing system that calculates a correction factor for each electric motor's speed reference based on its own parameter, such as electric current, to balance power distribution without direct communication between motors, using separate control units and low-pass filters to optimize motor performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If decentralized speed control is used for each electric motor, then robust propeller speed control and motor independence are improved, but disparity in power supplied by motors increases leading to overheating and potential failure

Engineering Contradiction:
Improvemotor independence and robust speed controlVSAvoidmotor heating
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent implements a feedback mechanism where each motor's controller monitors its own speed and power output, and automatically adjusts its speed setpoint based on measured discrepancies. This closed-loop feedback enables motors to self-regulate and balance their power contribution without external communication, resolving the contradiction between motor independence and power balancing.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system dynamically changes the speed setpoint parameter for each motor based on real-time operating conditions and measured power disparities. By adjusting this key parameter individually for each motor while maintaining decentralized control, the system achieves power balancing without compromising motor independence or requiring inter-motor communication.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If communication between electric motors is established for balancing, then power distribution is improved, but system complexity and troubleshooting difficulty increase

Engineering Contradiction:
Improvepower balancingVSAvoidcommunication connections
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

Each motor controller independently performs power balancing by monitoring its own performance parameters and automatically adjusting its speed setpoint. This self-service approach eliminates the need for communication infrastructure between motors, reducing system complexity while achieving effective power balancing through autonomous decision-making at each motor controller.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent segments the power balancing function into independent operations at each motor controller, rather than implementing it as a centralized or inter-connected system. Each controller operates autonomously with its own balancing logic, which simplifies the overall system architecture by removing communication requirements while maintaining effective power distribution control.

Inventive Principle:
Principle #1Segmentation

3Reliability

If multiple electric motors are used for propulsion redundancy, then safety and propulsion capability are improved, but disparity in power output increases causing overheating risks

Engineering Contradiction:
Improvepropulsion redundancyVSAvoidoverheating and motor failure
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The system implements dynamic adjustment of each motor's speed setpoint based on real-time measurements of power output and temperature. This dynamic control allows motors to operate within safe thermal limits while maintaining redundancy capability, as each motor can independently adapt its contribution to prevent overheating while ensuring propulsion safety through the multi-motor configuration.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP4072944B1System and method for balancing at least one parameter to be balanced of an electric motor of a propulsion system
Publication Date: 2023.12.06 SAFRAN HELICOPTER ENGINES
  • EP4072944B1 patent drawingFigure 1
  • EP4072944B1 patent drawingFigure 2~3
  • EP4072944B1 patent drawingFigure 4

AI summary

System (11) for balancing at least one parameter to be balanced of an electric motor of a propulsion system (1), in particular of an aircraft, comprising at least two electric motors (3, 4) and a propulsion member (2) driven in rotation by said electric motors. The balancing system is configured to calculate a correction of the speed setpoint (Corr_Cons_VI, Corr_Cons_V2) as a function of a correction factor (F1, F2) of the speed setpoint depending on a parameter (P1, P2) of the associated electric motor that is intended to be balanced and on a speed setpoint (Cons_VH) of the propulsion member (2).