Sensorless Motor Control for Aerial Vehicles at Low Speeds
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Solution Overview
Problem
Conventional sensorless motor control techniques are unreliable and inaccurate at low speeds and during speed reversals, especially in the presence of external forces, loads, or torques, which affects the control of aerial vehicle propulsion mechanisms.
Innovation Solution
The implementation of a sensorless motor control system that includes a motor back EMF observer, adaptive EMF filter, magnitude attenuation compensation, hybrid rotor position and speed determination, rotor position and speed blending, and angle or phase delay compensation to accurately control motors across all speed ranges, including low speeds and during speed reversals, even in degraded operational states and with external influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional sensorless motor control techniques are used, then device complexity is reduced, but measurement precision and reliability deteriorate at low speeds and during speed reversals
Solution Approach 1:
The patent segments the speed range into different operating regions (low speed, medium speed, high speed) and applies different control strategies to each. At low speeds and during reversals, it uses active sensing methods with injected signals, while at higher speeds it transitions to conventional sensorless control based on back-EMF estimation, thus achieving high precision without requiring complex sensing across all operating conditions
Solution Approach 2:
The patent applies preliminary action by injecting excitation signals into the motor windings before actual operation to enable rotor position and speed estimation. This preliminary signal injection allows the system to establish accurate initial conditions and maintain reliable sensing during low-speed and reversal operations where conventional methods fail
2Reliability
If conventional sensorless motor control techniques are used, then control system simplicity is maintained, but reliability deteriorates in the presence of external forces, loads, or torques
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor motor current, voltage, and estimated rotor position to detect disturbances caused by external forces and loads. The control algorithm adjusts injection signals and estimation parameters in real-time based on feedback, maintaining reliable operation under varying load conditions and external disturbances
Solution Approach 2:
The patent dynamically changes control parameters such as injection signal frequency, amplitude, and phase based on operating conditions including load torque and speed. This parameter adaptation allows the system to maintain reliability across different operational states without requiring a fundamentally complex control architecture
3Speed
If conventional sensorless motor control techniques are used, then system simplicity is maintained, but agility and responsiveness deteriorate at low speeds and during speed reversals
Solution Approach 1:
The patent employs dynamic control by continuously adapting the injection signal characteristics and estimation algorithms based on real-time speed and load conditions. This dynamic adjustment enables the system to respond rapidly to speed changes and reversals while maintaining accurate rotor position and speed estimation, thus achieving both agility and reliability
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 reliable and precise control of aerial vehicle propulsion mechanisms over a wide range of speeds and in various operational conditions, including low speeds and speed reversals, and in the presence of external forces, loads, or torques, enhancing agility and responsiveness.
Implementation Method 1
Conventional sensorless motor control techniques may rely upon estimated motor back EMF (electromotive force) for motor control
Implementation Method 2
The adaptive EMF filter may be configured to filter the noisy estimated motor back EMF signal
Data Source
AI summary
Systems and methods for sensorless motor control may include a back EMF (electromotive force) observer, an adaptive EMF filter, magnitude compensation, hybrid rotor position and speed determination, rotor position and speed blending, and angle compensation. In order to provide accurate and reliable rotor position and speed estimations for a motor over a wide and varied range of speeds, at low speeds, during speed reversals, and/or in the presence of external forces, loads, or torques, the sensorless motor control may utilize a hybrid rotor position and speed determination that leverages both angle-based and magnitude-based methods. Further, the outputs of the two methods may be blended based on a shaping function to generate a final estimated rotor position and speed. Then, the motor may be more accurately and reliably controlled based on the final estimated rotor position and speed.