Electric Actuator Positioning via Load-Torque Rotation Counting
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Solution Overview
Problem
Existing actuators with electric motors and controllers face challenges in achieving accurate positioning of actuated parts, particularly in HVAC applications, due to system hysteresis and inefficiencies in detecting load torque, leading to inaccuracies in fluid flow regulation and energy efficiency.
Innovation Solution
The actuator system includes a controller that determines the actuated position by counting motor rotations only when the motor is operating above a threshold indicative of load torque, excluding idle operations, and adapts to changes by recording the motor current and defining thresholds to account for system hysteresis and potential malfunctions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the controller counts all motor rotations to determine actuated position, then the positioning coverage is complete, but the positioning precision deteriorates due to inclusion of idle rotations during directional changes
Solution Approach 1:
The patent applies local quality by differentiating between different phases of motor operation. The controller selectively counts rotations only during load torque phases (when the actuated part is actually being moved) while excluding idle rotations during directional changes. This selective counting based on local operational conditions resolves the contradiction by ensuring precision without losing essential position information.
Solution Approach 2:
The patent implements dynamics by making the rotation counting function adaptive rather than static. The controller dynamically adjusts its counting behavior based on real-time detection of load torque conditions. When load torque is detected, rotation counting is enabled; when idle conditions are detected, counting is suspended. This dynamic approach maintains positioning precision while preserving complete position information throughout the full range of motion.
2Adaptability or versatility
If the controller adapts to system changes by recording motor current courses, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The patent applies feedback by having the controller record motor current courses during operation and use this recorded information to adapt to system changes. The controller monitors current consumption patterns, compares them against recorded courses, and adjusts its rotation counting behavior accordingly. This feedback mechanism enables the system to adapt to wear, environmental factors, and operational variations without requiring complex external sensors or additional hardware.
Solution Approach 2:
The patent implements self-service by enabling the controller to automatically adapt to system changes using its own operational data. The controller records motor current courses during normal operation and uses this self-generated information to maintain accurate positioning without external intervention. This self-service approach increases adaptability while minimizing additional device complexity.
Data Source
AI summary
An actuator (1) comprises an electric motor (11) for moving an actuated part (2) to an actuated position. The actuator (1) further comprises a controller (10) connected to the electric motor (11) and configured to determine a motor current of the electric motor (11) and to detect motor rotations. The controller (10) is further configured to determine the actuated position by counting the motor rotations detected while the motor current is at or above a current threshold indicative of a load torque, and by not counting motor rotations detected while the motor current is below said current threshold.