Linear Compressor Relay Failure Detection for Accurate Stroke Control
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Solution Overview
Problem
Linear compressors face challenges in accurately controlling operation when a relay failure occurs, leading to inaccurate computation of stroke and phase difference between stroke and current, resulting in inefficient operation modes and potential increased repair costs.
Innovation Solution
A linear compressor system that includes a control unit capable of determining the magnitude of currents in different relay states, comparing these magnitudes to assess relay operation, and resetting parameters to maintain accurate operation, even when a relay fails, by using a current detection unit and a relay that changes operation modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If relay operation is used to switch operation modes, then power consumption can be reduced, but reliability deteriorates when relay failure occurs
Solution Approach 1:
The control unit continuously monitors the current flowing through the linear motor and compares it against expected current values for different operation modes. This feedback mechanism allows the system to detect when the relay fails to switch modes properly and automatically adjusts control parameters to compensate, maintaining reliable operation even when the relay is defective
Solution Approach 2:
The system uses its own operational parameters (current, voltage, temperature) to self-diagnose relay status and self-correct control strategies without external intervention. When relay failure is detected, the control unit automatically switches to alternative control modes, enabling the system to service itself and maintain functionality
2Manufacturing precision
If relay failure occurs, then device complexity increases due to need for diagnosis and compensation, but manufacturing precision is maintained
Solution Approach 1:
The control unit performs multiple functions: normal motor control, relay status monitoring, fault diagnosis, and parameter compensation. By making the control unit multi-functional, the system avoids adding separate dedicated hardware for each function, thus managing complexity while maintaining precision through integrated software-based solutions
3Ease of operation
If relay failure is not detected, then ease of operation is maintained, but loss of information increases due to inaccurate stroke and phase difference computation
Solution Approach 1:
The control unit continuously monitors operational parameters and compares them against expected values. When discrepancies indicate relay failure, the system receives feedback about the fault condition and automatically adjusts control strategies to maintain accurate stroke and phase difference computation despite the relay defect
Solution Approach 2:
The system performs preliminary diagnosis by monitoring current patterns that indicate relay status before failure completely impacts operation. By detecting early signs of relay failure through current analysis, the system can proactively adjust control parameters to prevent inaccurate stroke computation, maintaining information accuracy before the problem fully manifests
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 accurate control of the linear compressor's operation and reduces unnecessary repair costs by diagnosing relay failures and maintaining optimal conditions, allowing for precise computation of stroke and phase difference, even when the relay is not functioning correctly.
Implementation Method 1
A linear motor may generate a linear driving force
Implementation Method 2
a current detection unit configured to sense a current in the linear motor
Data Source
AI summary
A linear compressor includes a cylinder, a piston, a linear motor configured to drive the piston, a current detection unit configured to sense a current in the linear motor, a relay configured to change an operation mode of the linear motor, and a control unit configured to set at least one parameter for determining a stroke of the piston according to the operation mode. The control unit is configured to: determine a first magnitude of a first current in the linear motor based on a state of the relay being in a first state, determine a second magnitude of a second current in the linear motor based on the relay being switched to a second state from the first state, compare the first magnitude to the second magnitude, and based on the comparison of the first magnitude to the second magnitude, determine whether the relay fails to operate.