Device and method for controlling linear compressor
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Solution Overview
Problem
Linear compressors face a trade-off between efficiency and maximum freezing capacity due to frictional losses, where reducing piston initial value increases efficiency but decreases freezing capacity, and increasing it enhances freezing capacity but increases frictional losses and reduces efficiency.
Innovation Solution
A control module for linear compressors that generates an asymmetric motor current by applying a current offset to adjust the piston's initial position, allowing for increased freezing capacity while maintaining efficiency by controlling the piston push amount and using a virtual capacitor for resonance operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the piston initial value is reduced to decrease stroke, then frictional loss is reduced and compressor efficiency is improved, but maximum freezing capacity is reduced
Solution Approach 1:
The patent applies dynamics by making the piston initial position adjustable rather than fixed. The controller dynamically changes the initial position of the piston based on operating conditions, allowing the system to optimize between efficiency and capacity requirements. This is achieved through controlling the motor current to position the piston at different initial locations within the cylinder.
Solution Approach 2:
The patent changes the parameter of piston initial position to resolve the contradiction. By varying this parameter, the system can operate at different points on the efficiency-capacity trade-off curve. The controller adjusts the initial position parameter based on detected operating conditions, enabling optimal performance across different loading scenarios.
2Productivity
If the piston initial value is increased to improve maximum freezing capacity, then freezing capacity is improved, but moving distance increases and frictional loss increases reducing efficiency
Solution Approach 1:
The system dynamically adjusts the piston initial position based on real-time detection of operating conditions. When high freezing capacity is required, the initial position is increased; when efficiency is prioritized, the initial position is reduced. This dynamic adaptation allows the system to resolve the contradiction by selecting the appropriate operating point.
Solution Approach 2:
The patent implements feedback control where the controller detects operating conditions and adjusts the piston initial position accordingly. This closed-loop control enables the system to respond to changing demands and maintain optimal performance, resolving the efficiency-capacity contradiction through continuous monitoring and adjustment.
3Productivity
If voltage is varied to control stroke and freezing capacity, then freezing capacity control is achieved, but additional control components and complexity are required
Solution Approach 1:
The patent replaces traditional mechanical stroke control mechanisms with electrical control of the linear motor. By controlling the motor current and initial position electrically rather than mechanically, the system achieves freezing capacity control with reduced mechanical complexity and fewer moving parts.
Solution Approach 2:
The system controls freezing capacity by changing electrical parameters (motor current, initial position) rather than mechanical parameters (voltage, stroke length). This parameter substitution simplifies the control system by using electrical control mechanisms that are more compact and easier to regulate than traditional mechanical systems.
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
The solution effectively increases maximum freezing capacity and maintains compressor efficiency by optimizing the piston's initial position and using a virtual capacitor for stable operation, reducing fabricating costs and managing overload voltage.
Implementation Method 1
a piston is directly connected to a mover of a linear motor so as to perform a reciprocating motion in response to a linear motion of the motor
Implementation Method 2
at least one spring which is installed to elastically support the movable member in a motion direction of the movable member
Implementation Method 3
a reciprocating compressor is configured in such a manner that a piston linearly reciprocates within a cylinder to suck, compress and discharge refrigerant gas
Data Source
AI summary
The control module includes a drive circuitry that drives the linear compressor based on a control signal, a detector that detects a motor current and a motor voltage corresponding to a motor of the linear compressor, an asymmetric current generator that generates an asymmetric motor current by applying a current offset to the detected motor current, and a controller that generates the control signal based on the asymmetric motor current and the detected motor voltage. Such a control module may increase a maximum freezing capacity by appropriately (or optimally) designing (setting) an initial value of a piston in a driving area or an operation area (or a high-efficiency driving area) of a compressor by considering the efficiency aspect, and executing an asymmetric operation in a high-load driving area (or a high freezing capacity driving area).