Method for operating a linear compressor

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Solution Overview

Problem

Existing linear compressors face challenges in accurately controlling piston motion to avoid hard head crashing and determining suction and discharge pressures without costly sensors.

Innovation Solution

A method that calculates observed velocities and positions using electrical and mechanical dynamic models, estimating clearance and pressures without position or pressure sensors, and updates these estimates based on errors between observed and calculated values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If hard head crashing is avoided by accurately controlling piston motion, then component damage is prevented, but control difficulty increases due to the need for precise positioning without position sensors

Engineering Contradiction:

Improveprevention of component damageVSAvoidcontrol difficulty

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces mechanical position sensing systems with an electrical dynamic model-based estimation system. The controller uses electrical measurements (current, voltage) and a dynamic model of the motor to calculate piston position, velocity, and acceleration, eliminating the need for physical position sensors while maintaining reliable control to prevent hard head crashing

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary estimation system that translates easily measurable electrical parameters into difficult-to-obtain mechanical position information. The dynamic model acts as a mediator, converting electrical current and voltage data into accurate piston position estimates without requiring direct mechanical measurement

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If pressure sensors are used to accurately determine suction and discharge pressures, then measurement accuracy is improved, but system cost increases

Engineering Contradiction:

Improvepressure measurement accuracyVSAvoidsystem cost

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical pressure sensing systems with an electrical model-based estimation system. The controller uses the electrical dynamic model, incorporating current, voltage, and motor parameters, to calculate suction and discharge pressures without requiring physical pressure sensors, thereby reducing system cost while maintaining measurement accuracy

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a virtual copy of the pressure measurement function through mathematical modeling. Instead of physically measuring pressure with sensors, the system computes pressure values by solving the electrical dynamic model equations, effectively copying the measurement capability through calculation rather than physical detection

Inventive Principle:

Principle #26Copying

3Measurement precision

If position sensors are installed to accurately determine piston position, then control precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvepiston position accuracyVSAvoidsensor requirements

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system uses its own electrical characteristics (current, voltage, motor parameters) to determine its mechanical state (position, velocity, acceleration). The motor's electrical behavior serves as the sensing mechanism, allowing the system to self-diagnose its position without external sensors

Inventive Principle:

Principle #25Self-service

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 accurate operation of linear compressors by avoiding hard head crashing and determining suction and discharge pressures without the need for costly sensors, improving control and efficiency.

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

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

calculating an observed position of the piston by integrating the second observed velocity for the piston

Methodology Applied

Scientific EffectIntegration of velocity to determine position:

Data Source

PatentUS10641263B2Method for operating a linear compressor

Publication Date: 2020.05.05 UNIVERSITY OF LOUISVILLE RESEARCH FOUNDATION INC

AI summary

A method for operating a linear compressor includes substituting a first observed velocity, a bounded integral of the first observed velocity, an estimated clearance, an estimated discharge pressure, and an estimated suction pressure into the mechanical dynamic model for the motor, calculating an observed acceleration for the piston with the mechanical dynamic model for the motor, calculating a second observed velocity for the piston by integrating the observed acceleration for the piston, calculating an observed position of the piston by integrating the second observed velocity for the piston, and updating an estimated clearance, an estimated discharge pressure, and an estimated suction pressure based upon an error between the first and second observed velocities and an error between the bounded integral of the first observed velocity and the observed position.