Sensorless UAV Motor Starting from Unknown Propeller Rotation
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Solution Overview
Problem
Unmanned aerial vehicles (UAVs) equipped with sensorless motors face challenges in starting the motor when the rotation rate and direction are unknown, particularly in high altitude long endurance applications.
Innovation Solution
A system that includes a microcontroller communicating with a sensorless motor, which determines the rotation rate and direction of the propeller and provides outputs to stop or start the propeller based on desired parameters, using measured back electromotive force (EMF) frequency for rotation rate determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sensorless motors are used in UAVs to reduce complexity, then device complexity is reduced, but the ability to determine rotation rate and direction becomes difficult
Solution Approach 1:
The motor system uses its own back-EMF signal for speed detection, eliminating the need for external sensors. The back-EMF frequency directly indicates rotor speed, allowing the system to self-diagnose and self-regulate without additional sensing components.
Solution Approach 2:
The patent replaces mechanical sensing systems (encoders, resolvers) with an electrical measurement system that detects back-EMF frequency. This substitution eliminates mechanical sensors while maintaining speed detection capability through electrical signal analysis.
2Ease of operation
If the motor starts with unknown rotation rate and direction, then ease of operation is improved, but reliability of motor starting deteriorates
Solution Approach 1:
The system performs preliminary detection of back-EMF frequency and direction before initiating the starting sequence. This preliminary information is used to pre-configure the inverter parameters, ensuring reliable starting from any initial state without requiring manual intervention or complex control algorithms.
Solution Approach 2:
The system continuously monitors back-EMF frequency during the starting process and uses this feedback to adjust inverter parameters in real-time. This closed-loop control ensures the motor starts reliably regardless of initial rotation rate or direction, automatically adapting to the actual motor state.
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
Enables the reliable starting of sensorless motors in UAVs by accurately determining and adjusting the rotation rate and direction, ensuring proper operation even with unknown initial conditions.
Implementation Method 1
the determined rotation rate is based on a measured frequency of a back electromotive force (EMF) generated by at least one sensorless motor
Data Source
AI summary
Systems, devices, and methods for: an unmanned aerial vehicle (UAV); at least one sensorless motor of the UAV, the at least one sensorless motor comprising a set of windings and a rotor; at least one propeller connected to the at least one sensorless motor; a microcontroller in communication with the at least one sensorless motor, wherein the microcontroller is configured to: determine a rotation rate of the at least one propeller; determine a rotation direction of the at least one propeller; provide an output to stop the at least one propeller if at least one of: the determined rotation rate is not a desired rotation rate and the determined rotation direction is not a desired rotation direction; and provide an output to start the at least one propeller if the at least one propeller is stopped at the desired rotation rate and the desired rotation direction.