Ferrite Magnet Compressor Motor Low-Temperature Demagnetization
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Solution Overview
Problem
Current electric motors, particularly those used in compressors, are costly and have unstable prices due to reliance on rare-earth materials, leading to high costs and performance instability.
Innovation Solution
The use of ferrite permanent magnet synchronous motors in electric motors and compressors, along with a heating element to prevent ferrite magnet demagnetization, allows for reduced costs and performance comparable to rare-earth motors while controlling input current to protect the ferrite magnets from irreversible demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rare-earth permanent magnet synchronous motors are used, then motor performance is improved, but costs increase and price stability deteriorates
Solution Approach 1:
The patent changes the material parameter from rare-earth permanent magnets to ferrite permanent magnets, fundamentally altering the cost structure while maintaining acceptable performance through optimized motor design and control parameters
Solution Approach 2:
The patent replaces expensive rare-earth materials with cheaper ferrite materials, accepting that ferrite has lower intrinsic performance but compensating through system-level optimizations to achieve cost reduction while maintaining functional equivalence
2Ease of manufacture
If ferrite permanent magnet synchronous motors are used, then costs are reduced, but risk of demagnetization increases
Solution Approach 1:
The patent applies preliminary heating to the ferrite magnets before motor operation to ensure they are above the Curie temperature threshold, preventing demagnetization during subsequent low-temperature operation. This proactive measure eliminates the reliability risk before it can manifest
Solution Approach 2:
The patent introduces a heating element as an intermediary device that mediates between the electrical system and the ferrite magnets, providing thermal management to maintain magnet stability. The heating element acts as a buffer that prevents direct thermal shocks from demagnetizing the magnets
3Reliability
If heating element is added to prevent demagnetization, then magnet stability is improved, but device complexity increases
Solution Approach 1:
The heating element is designed to serve multiple functions: it heats the ferrite magnets to prevent demagnetization, and can also serve as a temperature sensor or part of the thermal management system. This multi-functionality reduces the need for separate components, offsetting the added complexity
Solution Approach 2:
The patent merges the heating function with existing motor components or integrates the heating element directly into the magnet assembly, combining thermal management with the motor structure. This integration approach minimizes the increase in device complexity by eliminating separate thermal management subsystems
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
This solution significantly reduces the costs of electric motors and compressors while maintaining performance equivalent to rare-earth systems, enhancing reliability by preventing irreversible demagnetization of ferrite magnets at low temperatures.
Implementation Method 1
a heating element disposed on a surface of or near the ferrite magnet of the rotor and used for heating the ferrite magnet
Implementation Method 2
single-phase or multiphase windings disposed on the stator; and a rotor, where the rotor includes a permanent magnet
Data Source
AI summary
An electric motor, a compressor including the electric motor and a method for controlling the electric motor or the compressor are provided. The electric motor includes: a stator; single-phase or multiphase windings disposed on the stator; and a rotor, where the rotor includes a permanent magnet, and at least part of the permanent magnet is ferrite. By using a permanent magnet synchronous motor in a variable-speed compressor, costs of the variable-speed compressor are significantly reduced, and the performance thereof is basically the same as that of a variable-speed compressor using a rare-earth permanent magnet synchronous motor. By controlling the electric motor or the compressor, costs of the electric motor or the compressor are reduced, and moreover, and the ferrite in the electric motor can be protected from irreversible demagnetization at a low temperature, thereby improving the reliability of the compressor.