Linear Compressor Control Avoiding Mechanical Resonance
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Solution Overview
Problem
Linear compressors face inefficiencies and noise issues due to mechanical resonance phenomena, limiting the variability of operating frequency and causing vibration and noise, especially when load variations affect the natural frequency of the piston.
Innovation Solution
An apparatus and method for controlling the linear compressor that includes a detector to assess the operating state, a controller to generate correction signals for the linear motor's operating frequency, and a drive signal generator to adjust the motor's frequency within a predetermined range around a reference frequency, preventing mechanical resonance by continuously changing the actual operating frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operating frequency of the linear motor is set to coincide with the natural frequency of the piston for maximum efficiency, then energy use efficiency is improved, but mechanical resonance phenomena occur causing noise and vibration
Solution Approach 1:
The patent applies dynamics by making the operating frequency variable rather than fixed. The control unit continuously adjusts the operating frequency of the linear motor based on real-time detection of piston position and compression load, allowing the system to dynamically avoid resonance frequencies while maintaining high efficiency operation across varying load conditions
Solution Approach 2:
The patent changes the parameter of operating frequency from a fixed value to a variable parameter that is continuously adjusted. By detecting piston position and compression load, the system modifies the operating frequency to stay near the natural frequency for efficiency while avoiding exact resonance conditions that cause noise and vibration
2Productivity
If the operating frequency is fixed at the natural frequency for optimal performance, then compression efficiency is maximized, but the system cannot adapt to load variations that change the natural frequency
Solution Approach 1:
The patent implements feedback control by detecting piston position and compression load, comparing the current operating conditions with the natural frequency characteristics, and adjusting the operating frequency accordingly. This closed-loop feedback system enables the compressor to adapt to load variations while maintaining optimal compression efficiency
Solution Approach 2:
The system transitions from a static fixed-frequency operation to dynamic frequency adjustment. The operating frequency is continuously modified based on real-time detection of load changes and piston position, allowing the system to adapt to varying natural frequencies while maintaining high compression efficiency across different operating conditions
3Object-generated harmful factors
If the operating frequency is varied to avoid resonance, then noise and vibration are reduced, but energy use efficiency decreases when not operating at the natural frequency
Solution Approach 1:
The patent optimizes the parameter adjustment strategy by making minimal frequency deviations from the natural frequency. Instead of large frequency shifts, the system makes small, precise adjustments that stay close to the natural frequency, thereby maintaining high energy efficiency while sufficiently avoiding resonance conditions that cause noise and vibration
4Adaptability or versatility
If the natural frequency changes with load variations, then the system can handle different compression demands, but the fixed operating frequency becomes mismatched causing inefficiency
Solution Approach 1:
The system uses feedback control to detect changes in compression load and piston position, determines the corresponding natural frequency shift, and adjusts the operating frequency to track the natural frequency. This ensures the operating frequency remains matched to the changing natural frequency under different compression demands, maintaining high energy efficiency
Solution Approach 2:
The patent implements dynamic frequency tracking where the operating frequency automatically adapts to load variations. As the compression demand changes and the natural frequency shifts, the control unit continuously adjusts the operating frequency to follow the natural frequency, ensuring optimal energy efficiency across the full range of compression demands
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 the operating efficiency of the linear compressor, reduces noise and vibration, and allows for flexible frequency adjustment, preventing mechanical resonance and maintaining optimal efficiency.
Implementation Method 1
a permanent magnet may be provided to be connected to the piston in the gap between the inner stator and the outer stator. The permanent magnet may be provided to be movable in a moving direction of the piston, and may be linearly reciprocate in the moving direction of the piston by an electromagnetic force generated according to a current flow in the coil
Implementation Method 2
a coil spring, which is a type of mechanical spring, may be mounted to be elastically provided in the sealed container and the cylinder in the moving direction of the piston
Implementation Method 3
In addition, refrigerant suctioned into the compression space may also serve as a gas spring. The coil spring may have a predetermined mechanical spring constant (Km), and the gas spring may have a gas spring constant (Kg) that varies according to load
Implementation Method 4
The piston may linearly reciprocate inside of the cylinder, and thereby a refrigerant may be allowed to flow into a compression space inside the cylinder, be compressed, and then discharged
Data Source
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Figure 3~5
AI summary
In accordance with one aspect of the present invention, an apparatus for controlling a linear compressor, includes: a detector that detects an operating state of the linear compressor; a controller that outputs a correction signal for correcting at least an operating frequency of a linear motor based on the operating state; and a drive signal generator that generates a drive signal of the linear motor according to the correction signal, and outputs the generated drive signal to the linear motor, wherein the controller includes: a reference operating frequency determiner that determines a reference operating frequency at which the linear motor is operated; and an actual operating frequency determiner that determines an actual operating frequency as an arbitrary value included in a predetermined numerical value range around the reference operating frequency, wherein the correction signal is determined based the actual operating frequency.