Dynamic Torque Limiting for Multi-Motor Rotorcraft Power Distribution
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Solution Overview
Problem
Rotorcrafts with three motors of non-equal power distribution face performance degradation due to torque limitations, as conventional methods set constant or adjustable torque limits that do not account for varying power distribution among motors, leading to potential overloading of some motors and underutilization of others.
Innovation Solution
A method that dynamically adjusts engine torque limits for each motor based on the distribution of total power among the motors, using distribution coefficients calculated by the control computer to ensure each motor operates within its adapted torque limit, optimizing performance across different flight stages and conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant or adjustable torque limits are set for motors, then torque protection is provided, but performance is degraded due to underutilization of motors with higher power capability
Solution Approach 1:
The patent applies dynamics by transitioning from static torque limits to dynamic torque limits that adapt in real-time based on actual power distribution. The control system continuously monitors the operating state of each motor and adjusts the torque limits accordingly, allowing motors with higher power capability to contribute more when available, while maintaining protection when limits are reached. This resolves the contradiction by making the protection system flexible rather than rigid.
Solution Approach 2:
The patent changes the parameter of torque limits from fixed values to variable values that depend on the operating conditions and power distribution among motors. By calculating and adjusting torque limits based on the ratio of each motor's power to total power, the system optimizes performance while maintaining reliability. This parameter adaptation allows motors to operate closer to their actual capabilities without risking overload.
2Reliability
If torque limits are set to protect the rotorcraft, then safety is ensured, but some motors cannot operate at full power leading to inefficiency
Solution Approach 1:
The patent implements feedback by continuously monitoring the operating state of each motor, including current torque and power output, and using this information to dynamically adjust torque limits. The control system receives feedback from each motor's performance and modifies the limits in real-time, allowing motors to operate at higher efficiency when conditions permit while maintaining safety margins when approaching limits. This closed-loop control resolves the contradiction between safety and efficiency.
3Device complexity
If equal torque limits are applied to all motors, then simplicity is maintained, but motors with different power ratings cannot operate optimally
Solution Approach 1:
The patent applies local quality by assigning different torque limits to different motors based on their individual characteristics and current power contribution. Instead of a uniform approach, each motor receives a customized torque limit calculated from its power rating and actual operating state. This allows motors with higher power ratings to have higher torque limits when they contribute more power, optimizing overall system performance without significantly increasing complexity through automated calculations.
Data Source
AI summary
A method for limiting torque on a rotorcraft. The rotorcraft comprises an installation having a rotor, the installation including at least three motors driving a power transmission gearbox, the MGB including a rotor mast for moving the rotor. The method comprises a step of determining a engine torque limit for each of at least the three motors, each engine torque limit being established by a control computer of the aircraft by taking into consideration the distribution among the at least three motors of the total power (Ptot) delivered by the at least three motors for enabling the rotorcraft to operate.