Linear compressor and linear compressor control system
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Solution Overview
Problem
Existing linear compressor control systems rely on sensor-based methods to detect and control the position of the mover, which are unreliable due to assumptions about the position dependency of the induced voltage coefficient and require additional device size for sensors, leading to inaccuracies and increased costs.
Innovation Solution
A linear compressor and control system that utilize a field element with a permanent magnet and an armature with windings, where the control device adjusts the voltage based on current flow to maintain a predetermined induced voltage gradient, allowing for accurate position detection without sensors by correlating the induced voltage with the top and bottom dead centers of the piston stroke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sensor is used to measure the position of the mover, then the position detection reliability is improved, but the device size and cost increase
Solution Approach 1:
The patent replaces the mechanical sensor-based position detection system with an electromagnetic field-based detection system. By measuring the induced voltage in the armature winding, which is directly related to the mover position through the elastic body's mechanical characteristics, the system eliminates the need for physical position sensors while achieving accurate position detection.
Solution Approach 2:
The patent introduces the induced voltage as an intermediary parameter to detect mover position. Instead of directly measuring position with a sensor, the system measures the induced voltage in the winding, which serves as a mediator that reflects the mover's position through the relationship e(t) = αv(t), where the induced voltage coefficient α is determined by the elastic body's mechanical properties.
2Device complexity
If the induced voltage coefficient is assumed to be constant, then the computation is simplified, but the position computation accuracy deteriorates
Solution Approach 1:
The patent changes the approach from assuming a constant induced voltage coefficient to determining it as a variable parameter based on the elastic body's mechanical characteristics. By establishing the relationship between the induced voltage coefficient and the elastic body's stiffness and mass, the system accurately determines α for each operating condition, thereby improving position computation accuracy without excessive computational complexity.
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 high-accuracy position computation of the mover without the need for sensors, considering the position dependency of the induced voltage constant, thereby reducing device size and costs while maintaining reliable position detection.
Implementation Method 1
a linear motor that causes the field element and the armature to reciprocate relatively in an axial direction
Implementation Method 2
an induced voltage that is computed on the basis of a voltage command value output to the linear motor and a value of a current flowing through the winding
Data Source
AI summary
Provided are a linear compressor and a linear compressor control system that do not require a sensor for detecting a position of a mover, and can compute a mover position with high accuracy, in consideration of position dependency of an induced voltage constant. A linear compressor 20 includes a field element 11 having a first end connected to elastic bodies (201a and 201b) and including a permanent magnet 111, an armature 12 having a winding 122 wound around a magnetic pole 121, and a linear motor 10 that causes the field element 11 and the armature 12 to reciprocate relatively in an axial direction. A stroke of a piston is controlled so that a portion where a gradient of an induced voltage when the induced voltage computed on the basis of a voltage command value output to the linear motor 10 and a value of a current flowing through the winding 122 is at a predetermined value is within a predetermined range corresponds to a top dead center and/or a bottom dead center of a stroke of a piston 212 connected to a second end of the field element 11.