Hermetic Compressor Driving Device Overcurrent Protection
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Solution Overview
Problem
Conventional hermetic compressor driving devices often damage the current limiting element and switching circuit when an overload current occurs due to temporary refrigerant load increases, leading to unnecessary repairs or replacements, and the High Pressure Switch (HPS) does not operate effectively in such scenarios.
Innovation Solution
A hermetic compressor driving device with a parameter detection unit for overcurrent, bus voltage, and open phase detection, along with a control unit that determines the nature of abnormalities, allowing for resumption of operation if the issue is temporary and stopping the compressor if it's not, thereby preventing damage and unnecessary repairs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a normally open contact and current limiting element are directly connected to phase windings to detect overload current, then the hermetic compressor can be protected from abnormal pressure or temperature increases, but the current limiting element and switching circuit are damaged when temporary refrigerant load increases cause overload current
Solution Approach 1:
The patent introduces a diode as an intermediary component between the current limiting element and the switching circuit. This diode allows current to flow in only one direction, enabling the system to detect overload conditions while preventing harmful reverse current from damaging the switching circuit. The diode acts as a mediator that separates the detection function from the switching function, allowing the current limiting element to perform both detection and protection without causing damage to other components.
Solution Approach 2:
The patent segments the protection function into separate components: the current limiting element for detecting abnormal conditions, the diode for directional current control, and the switching circuit for controlling compressor operation. By dividing these functions into separate segments, the system can detect overload conditions and protect against damage without requiring all components to bear the full stress of abnormal conditions, thereby improving overall system reliability.
2Reliability
If the High Pressure Switch (HPS) is used to stop operations when pressure reaches a predetermined value, then the hermetic compressor can be protected from high pressure, but the HPS does not operate effectively when pressure increase is due to temporary refrigerant load increases
Solution Approach 1:
The patent implements a feedback mechanism where the control unit continuously monitors the current flowing through the current limiting element and the state of the HPS. When the HPS opens due to high pressure, the control unit detects the resulting current change and determines whether to resume operation. This feedback loop allows the system to distinguish between temporary pressure increases (where operation can resume) and persistent dangerous conditions (where operation should continue to be stopped), thereby improving operational ease while maintaining protection.
Solution Approach 2:
The patent makes the system's response dynamic by allowing automatic resumption of operation after HPS activation under certain conditions. Instead of a static stop-and-repair approach, the system dynamically adjusts its operation based on real-time monitoring of current and HPS state. When the control unit determines that the pressure increase was temporary and not dangerous, it automatically resumes operation without requiring manual intervention, making the system more adaptable to varying operating conditions.
Data Source
AI summary
A hermetic compressor driving device, which drives a hermetic compressor provided with an HPS (High Pressure Switch) therein, includes parameter detection units (a voltage detection unit, an overcurrent detection unit, and a position and open-phase detection unit) that detect an overcurrent, a bus voltage, and an open phase, which are generated during the opening operation of the HPS within the hermetic compressor; a temperature detection unit that detects the temperature of the hermetic compressor; and a control unit to which data acquired by the parameter detection units and the temperature detection unit is input. When detecting an abnormality on the basis of the data and upon determining the abnormality as a resumable abnormality, the control unit outputs a drive signal; and, upon determining the abnormality as being not a resumable abnormality, outputs an abnormality signal so as to stop the driving of the hermetic compressor.