Linear Compressor Resonance Control for Phase-Aligned Efficiency
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Solution Overview
Problem
Linear compressors face efficiency deterioration due to changes in the phase difference between piston stroke and motor current, which can be influenced by varying use environments, leading to suboptimal operation.
Innovation Solution
A control device for the linear compressor that dynamically adjusts the motor's operating frequency to maintain a resonant phase difference between the piston stroke and motor current, using sensors to detect motor current, voltage, and operational parameters to determine whether to perform a resonance operation or adjust the frequency based on load, refrigerant amount, and environmental conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the linear compressor operates with a fixed motor frequency, then the structure is simple, but the phase difference between piston stroke and motor current changes with use environment causing efficiency deterioration
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed motor frequency to a dynamically adjustable frequency system. The control device continuously monitors operational parameters (rotation speed, discharge temperature, current) and adjusts the motor frequency in real-time to maintain optimal phase difference, thereby adapting to varying use environments and preventing efficiency deterioration.
Solution Approach 2:
The patent implements parameter changes by modifying the motor operating frequency based on detected operational conditions. The control device calculates optimal frequency values that maintain resonant phase difference between piston stroke and motor current, and adjusts the inverter output accordingly to keep the compressor operating at peak efficiency across different environmental conditions.
2Loss of energy
If the motor frequency is dynamically adjusted to maintain resonant phase, then compressor efficiency is improved, but the control system complexity increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring operational parameters (rotation speed via crank angle sensor, discharge temperature via temperature sensor, and current via current sensor) and using this information to adjust the motor frequency. The control device calculates the phase difference based on detected values and modifies the inverter output to maintain optimal resonant phase, creating a closed-loop control system that balances efficiency improvement with manageable complexity.
3Loss of energy
If the phase difference between motor current and stroke is maintained at resonant phase, then operating efficiency is maximized, but the adaptability to varying use environments is reduced
Solution Approach 1:
The patent resolves this contradiction by making the system dynamic rather than static. Instead of fixing the phase relationship, the control device continuously adjusts the motor frequency to maintain resonant phase under varying environmental conditions. The system adapts to different rotation speeds, discharge temperatures, and load conditions by real-time frequency modulation, thereby maintaining high efficiency across diverse operating environments.
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 solution enhances compressor efficiency by maintaining optimal phase alignment with reduced power consumption and overcoming mechanical design limitations, allowing for efficient operation across varying conditions.
Implementation Method 1
the linear type compressor may include a piston connected to a mover of a linearly moving motor to make the piston reciprocate by virtue of the linear motion of the motor
Implementation Method 2
the MK resonant frequency may be defined by a mass M of a moving member including a piston and a permanent magnet and a spring constant K of springs supporting the moving member
Implementation Method 3
the linear compressor may follow a mass-spring (MK) resonant frequency in order to perform a resonance operation
Data Source
AI summary
A linear compressor includes, a cylinder, a piston configured to reciprocate inside the cylinder, a motor configured to supply driving force to the piston, a detector configured to detect a motor current and a motor voltage that are applied to the motor, and a controller configured to estimate a stroke of the piston based on the motor current and the motor voltage and to determine a phase difference between the stroke and the motor current. The controller is configured to detect operation information of the linear compressor, determine whether to perform a resonance operation based on the operation information, and control operation of the motor to allow the phase difference to be within a preset phase range.