Electric Motor Actuator Position Holding Using Cogging Torque
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Solution Overview
Problem
Actuators with electric motors in HVAC systems face challenges in maintaining target positions due to cogging torque, which results in inefficient energy usage and jerky movements, especially under dynamic external influences.
Innovation Solution
The actuator system includes a control circuit that determines stable positions and motor torque requirements, reducing torque when within defined ranges and increasing it when outside, using incremental steps to find the smallest torque needed to maintain position, and includes an energy store for power during failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If significant motor torque is applied to maintain target position under external forces, then position stability is improved, but electric energy consumption increases
Solution Approach 1:
The controller pre-determines a set of stable positions where cogging torque naturally balances external forces before actual position maintenance is needed. When the motor reaches one of these pre-calculated stable positions, the controller reduces motor torque to near-zero, allowing cogging torque to naturally maintain the position without continuous energy input.
Solution Approach 2:
The invention utilizes the motor's inherent cogging torque as a self-sustaining mechanism. By positioning the motor at stable positions where cogging torque naturally counteracts external forces, the system allows the motor to maintain position using its own inherent magnetic properties rather than requiring continuous external energy input.
2Use of energy by moving object
If motor torque is reduced to minimize energy consumption, then electric energy consumption decreases, but position maintenance capability deteriorates
Solution Approach 1:
The controller pre-determines a set of stable positions where cogging torque naturally balances external forces before actual position maintenance is needed. When the motor reaches one of these pre-calculated stable positions, the controller reduces motor torque to near-zero, allowing cogging torque to naturally maintain the position without continuous energy input.
Solution Approach 2:
The invention converts the typically harmful cogging torque, which causes jerky movements, into a beneficial force for position maintenance. By deliberately positioning the motor at stable positions where cogging torque aligns with external forces, the system transforms this parasitic effect into a useful mechanism that maintains position without requiring continuous energy input.
3Device complexity
If cogging torque is present in the electric motor, then motor structure is simplified, but movement smoothness deteriorates due to jerky movements
Solution Approach 1:
The controller pre-determines a set of stable positions where cogging torque naturally balances external forces before actual position maintenance is needed. When the motor reaches one of these pre-calculated stable positions, the controller reduces motor torque to near-zero, allowing cogging torque to naturally maintain the position without continuous energy input.
Solution Approach 2:
The invention converts the typically harmful cogging torque, which causes jerky movements, into a beneficial force for position maintenance. By deliberately positioning the motor at stable positions where cogging torque aligns with external forces, the system transforms this parasitic effect into a useful mechanism that maintains position without requiring continuous energy input.
4Measurement precision
If continuous motor torque is applied to counteract external forces, then position accuracy is improved, but energy efficiency deteriorates
Solution Approach 1:
The controller pre-determines a set of stable positions where cogging torque naturally balances external forces before actual position maintenance is needed. When the motor reaches one of these pre-calculated stable positions, the controller reduces motor torque to near-zero, allowing cogging torque to naturally maintain the position without continuous energy input.
Solution Approach 2:
The invention utilizes the motor's inherent cogging torque as a self-sustaining mechanism. By positioning the motor at stable positions where cogging torque naturally counteracts external forces, the system allows the motor to maintain position using its own inherent magnetic properties rather than requiring continuous energy input.
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
This approach reduces electric energy consumption by optimizing motor torque within stable positions, improving position maintenance and reducing energy wastage, while ensuring the actuated part can return to target positions efficiently even under external forces and power failures.
Implementation Method 1
Cogging torque of electrical motors is produced as a result of the interaction between permanent magnets of the rotor and the stator slots
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
For controlling an electric motor to maintain a current motor position, a motor controller determines the current motor position of the electric motor and selects (S41 ) from a set of stable positions, defined by cogging torque of the electric motor, a selected stable position closest to the current motor position. The controller controls the motor torque of the electric motor to maintain the motor position (S4) within a defined range around the selected stable position.