Linear Compressor Head Clearance Estimation Without Position Sensors
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Solution Overview
Problem
Linear compressors face challenges in avoiding head crashing, which can damage components, and existing methods often require position sensors for accurate control, making it difficult to prevent such crashes without them.
Innovation Solution
A method is developed to operate linear compressors by establishing a set of predictors and a model for estimated head clearance, using time varying voltage and electrical dynamic models to calculate motor parameters, and conducting best subsets regression to establish coefficients for avoiding head crashes without position sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a position sensor is used to control piston motion, then head crashing can be avoided, but device complexity and cost increase
Solution Approach 1:
The patent replaces the mechanical position sensing system with an electrical dynamic model that uses measured electrical parameters (voltage, current, frequency) to calculate motor velocity and stroke length. This substitution eliminates the need for physical position sensors while maintaining the ability to predict and avoid head crashing conditions.
Solution Approach 2:
The patent introduces an electrical dynamic model as an intermediary between the electrical inputs and mechanical outputs. This model acts as a mediator that translates electrical measurements into mechanical state predictions (velocity, stroke length), enabling indirect measurement of piston position without physical sensors.
2Reliability
If motor control is made more precise to avoid head crashing, then component damage is prevented, but control system complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the electrical dynamic model continuously calculates predicted velocity and stroke length based on measured electrical parameters. These predictions feed back into the control system to adjust operating conditions and avoid head crashing, creating a closed-loop control without complex sensors.
Solution Approach 2:
The system uses its own electrical measurements (voltage, current, frequency) to self-diagnose and predict mechanical state. The motor essentially monitors itself through its electrical characteristics, eliminating the need for external sensing systems and simplifying the overall control architecture.
3Device complexity
If electrical dynamic modeling is used to estimate head clearance, then position sensors can be eliminated, but measurement precision may be compromised
Solution Approach 1:
The patent transforms the measurement approach by changing from direct mechanical position measurement to indirect electrical parameter measurement. By measuring electrical parameters (voltage, current, frequency) and using the electrical dynamic model to calculate mechanical state, the system achieves sufficient precision for head crashing avoidance without direct position sensing.
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 method effectively prevents head crashing in linear compressors by adjusting motor voltage and current, allowing for robust control and efficient operation without the need for position sensors, thereby reducing component damage and improving compressor performance.
Implementation Method 1
A voltage excitation induces a current within the driving coil that generates a force for sliding the piston forward and backward within a chamber
Data Source
AI summary
A method for operating a linear compressor includes establishing a set of predictors, and establishing a model for an estimated head clearance of the linear compressor with the set of predictors. Coefficients of the model for the estimated head clearance of the linear compressor may also be established. The model for the estimated head clearance of the linear compressor may be used to calculate an estimated head clearance during operation of the linear compressor.