Actuator with automatic force setting and self-calibration
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Solution Overview
Problem
HVAC actuators face challenges in achieving accurate force output due to variations in motor back-electromotive force (BEMF) caused by inconsistencies in manufacturing and load conditions, leading to inefficiencies and potential motor stalling.
Innovation Solution
The method involves measuring the motor BEMF and adjusting the electrical current supply to match an expected BEMF value, using a force sensor to determine the relationship between current, BEMF, and force exerted, and storing data for future adjustments, enabling precise calibration and operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If standard motor current supply is used without calibration, then manufacturing simplicity is maintained, but force output accuracy deteriorates due to BEMF variations
Solution Approach 1:
The patent performs BEMF measurement and current calibration before actuator installation and use. A calibration routine measures the actual BEMF of each motor and determines the correction factor needed to achieve accurate force output. This preliminary calibration eliminates the need for complex real-time BEMF compensation hardware during operation.
Solution Approach 2:
The system measures the actual back-electromotive force (BEMF) generated by each motor and uses this feedback to calculate a correction factor for the supply current. The measured BEMF is compared against expected values, and the supply current is adjusted accordingly to compensate for manufacturing variations in motor constants.
2Measurement precision
If manual calibration procedures are used, then measurement accuracy can be achieved, but time consumption and operational complexity increase
Solution Approach 1:
The actuator performs its own BEMF measurement and calibration automatically during a startup routine or maintenance window. The motor is driven at a known speed, the actual BEMF is measured, and the correction factor is calculated and stored in the controller memory without requiring external measurement equipment or manual intervention.
Solution Approach 2:
The patent replaces manual measurement procedures with electronic BEMF sensing and automated calculation. Instead of using external test equipment and manual adjustments, the system uses the motor's own electrical characteristics (BEMF voltage) and a microcontroller to automatically determine and apply the necessary current correction.
3Reliability
If BEMF variations are not compensated, then system simplicity is maintained, but motor stalling and inefficiency increase
Solution Approach 1:
The patent changes the electrical parameter (supply current magnitude) based on the measured BEMF characteristics of each motor. By adjusting the current correction factor stored in memory, the system compensates for variations in motor constants and prevents stalling conditions without adding complex control hardware.
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 results in more accurate and efficient actuator operation with reduced human intervention, improving the calibration process and overall performance by ensuring the actuator works against known loads effectively.
Implementation Method 1
Back Electromotive Force\nBack electromotive force (BEMF), also known as counter-electromotive force (CEMF) is a voltage created in an electric motor's coils when its rotor is in motion. It is equivalent to the electromotive force (EMF) that is induced in an electrical generator.
Data Source
AI summary
Systems and methods for auto-calibration of current supplied to a motor of an actuator may include supplying an initial electrical current to the motor. One or more sensors may measure a condition corresponding to the motor as the initial electrical current is supplied to the motor. A processing circuit may compare the measured condition to an expected condition. The processing circuit may adjust a supply of the initial electrical current to the motor until the measured condition substantially matches the expected condition. The processing circuit may store data regarding an association between the adjusted supply of initial electrical current and the expected condition.