Resonant Linear Compressor Phase Control for Harmonic Avoidance
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Solution Overview
Problem
Resonant linear compressors face operational challenges when drive frequencies coincide with structural resonance frequencies, leading to potential damage, acoustic noise, and efficiency losses, as existing methods are either difficult to implement or result in reduced efficiency.
Innovation Solution
A method and system that alter the phase between the electric current and piston displacement velocity to prevent operation at structural resonance frequencies, employing a 'phase jump' strategy to avoid harmonics coinciding with structural resonances, thereby preventing damage and noise while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonant linear compressor operates at drive frequency whose harmonic coincides with structural resonance frequency, then the system reaches maximum efficiency, but the compressor suffers from acoustic noise, potential damage, and efficiency losses
Solution Approach 1:
The control system proactively detects when a harmonic of the drive frequency is approaching a structural resonance frequency and preemptively adjusts the drive frequency to avoid the harmful resonance condition. This preliminary anti-action prevents the harmful vibrations and noise before they occur, protecting the compressor from damage while maintaining reliable operation.
Solution Approach 2:
The system dynamically changes the drive frequency parameter in response to detected resonance conditions. When a harmonic coincides with a structural resonance frequency, the control system modifies the drive frequency to shift the harmonics away from the harmful resonance frequencies, thereby eliminating acoustic noise and vibrations while preserving compressor reliability.
2Object-affected harmful factors
If the drive frequency is adjusted to avoid structural resonance frequencies, then acoustic noise and vibrations are reduced, but the system efficiency decreases
Solution Approach 1:
The system implements dynamic frequency adjustment rather than static avoidance. The control system continuously monitors operational conditions and makes real-time, minimal adjustments to the drive frequency only when necessary to avoid resonance. This dynamic approach maintains the system at or near its optimal efficiency point while temporarily shifting frequency to eliminate harmful noise and vibrations during resonance conditions.
Solution Approach 2:
When a structural resonance frequency is detected, the system rapidly skips through the harmful frequency range by adjusting the drive frequency to bypass the resonance condition. This quick transition minimizes the time spent at inefficient frequencies, thereby reducing energy loss while still achieving the goal of eliminating acoustic noise and vibrations.
3Strength
If safety coefficient between maximum piston displacement and stroke end is increased, then piston impact damage is prevented, but the cooling capacity and output efficiency are reduced
Solution Approach 1:
The control system uses feedback from position sensors to monitor piston displacement in real-time. By continuously measuring the actual piston position and comparing it to the safe operating range, the system can dynamically adjust the drive frequency to maintain optimal piston stroke. This feedback mechanism ensures piston durability by preventing impacts while maximizing cooling capacity by minimizing unnecessary safety margins.
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
Effectively prevents resonant linear compressor operation at harmful frequencies, reducing noise and vibrations while ensuring operational reliability and efficiency by adjusting the phase between the electric current and piston displacement.
Implementation Method 1
the piston is actuated by a linear actuator, which comprises a support and magnets, being actuated by a coil
Implementation Method 2
a spring, which associates the movable part (piston, support and magnets) to the fixed part (cylinder, stator, coil, head and frame)
Implementation Method 3
The resonant assembly actuated by the linear motor has the function of developing a linear alternating movement
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A method for protecting a resonant linear compressor (14), such a compressor (14) comprising structural resonance frequencies (wE) and a motor that is fed by feed voltage (Va) that has amplitude (A) and a drive frequency (wA), both controlled according to the equation A.sen(wt). The protection method is configured so as to comprise the step of preventing feed to the motor at drive frequencies (wA) that have at least one harmonic coinciding tithe the structural resonance frequency (wE) of the resonant linear compressor (14).