Scroll Compressor Control Using Oil Temperature to Protect Ferrite Magnets
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Solution Overview
Problem
Conventional scroll compressors using ferrite permanent magnets are prone to demagnetization at low temperatures, and the integration of heating elements to prevent this is costly and difficult.
Innovation Solution
A scroll compressor with a synchronous reluctance motor and a lubricating oil temperature sensor, where the oil temperature indicates the rotor ferrite permanent magnet temperature, allowing controlled operation and heating to prevent demagnetization, using a heating apparatus and limited motor current to manage temperature restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a heating element is integrated into the rotor slot near the ferrite permanent magnet to prevent demagnetization, then the ferrite permanent magnet is protected from demagnetization at low temperatures, but the manufacturing cost and complexity increase significantly
Solution Approach 1:
The patent introduces lubricating oil as an intermediary thermal medium. The oil absorbs heat from the motor during operation and transfers it to the ferrite permanent magnet, preventing demagnetization without requiring direct heating elements. This indirect thermal coupling simplifies the structure while maintaining protection functionality.
Solution Approach 2:
The system uses the motor's own operational heat to protect the ferrite permanent magnet. The lubricating oil naturally circulates and distributes thermal energy within the motor assembly, converting the motor's waste heat into a protective resource for the magnet without requiring external heating systems.
2Reliability
If a heating element is integrated into the rotor slot to prevent demagnetization, then the ferrite permanent magnet temperature is maintained, but the manufacturing cost increases
Solution Approach 1:
Lubricating oil serves as a cost-effective thermal intermediary that naturally circulates within the motor assembly. It provides thermal coupling between the motor windings and the ferrite permanent magnet without requiring expensive specialized heating components, thereby reducing manufacturing costs while maintaining temperature control.
Solution Approach 2:
The lubricating oil performs multiple functions: it provides thermal coupling to prevent demagnetization, reduces friction in the motor, and cools the motor during operation. This multi-functionality eliminates the need for separate heating elements, reducing overall manufacturing complexity and cost.
3Adaptability or versatility
If the synchronous reluctance motor operates at low temperatures, then the compressor can function in cold environments, but the ferrite permanent magnet may demagnetize
Solution Approach 1:
The lubricating oil acts as a thermal intermediary that couples the motor's operational heat to the ferrite permanent magnet. This thermal coupling ensures that even when the external environment is cold, the magnet maintains sufficient temperature to prevent demagnetization, enabling reliable low-temperature operation.
Solution Approach 2:
The system uses temperature sensing to monitor the operational conditions and provides feedback to control the motor's operation. When temperatures approach thresholds that could cause demagnetization, the control system adjusts motor operation or activates heating mechanisms to maintain safe operating temperatures.
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
Prevents demagnetization of ferrite permanent magnets at low temperatures, ensuring reliable operation with cost-effective control features without additional components, and detects potential faults or failures.
Implementation Method 1
a heating apparatus, the heating apparatus being configured to heat lubricating oil stored in the lubricating oil tank
Implementation Method 2
a synchronous reluctance motor, the synchronous reluctance motor being arranged in the sealed housing and being configured to drive the drive shaft to rotate around the axis of rotation
Implementation Method 3
A lubricating oil temperature measured by the temperature sensor may act as an indication of a temperature of a rotor ferrite permanent magnet, because generally there is a good thermal connection between the lubricating oil tank and the rotor ferrite permanent magnet
Data Source
AI summary
A scroll compressor (2) includes a sealed housing (3); a compression unit (11), having a fixed scroll (12) and an orbiting scroll (13); a drive shaft (18) configured to drive the orbiting scroll (13) to move orbitally, the drive shaft (18) being capable of rotating about an axis of rotation; a synchronous reluctance motor (15) configured to drive the drive shaft (18) to rotate about the axis of rotation, the synchronous reluctance motor (15) comprising a rotor (16) coupled to the drive shaft (18) and a stator (17) disposed around the rotor (16), and the rotor (16) including a ferrite permanent magnet (23); a compressor control apparatus (31) configured to control the scroll compressor (2) to operate; a lubricating oil tank (27), formed in a bottom portion of the sealed housing (3); a heating apparatus configured to heat lubricating oil stored in the lubricating oil tank (27); and an oil temperature sensor (28) disposed in the lubricating oil tank (27).