IPM Rotor Slit Structure for Compressor Vibration Reduction
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Solution Overview
Problem
Interior permanent magnet motors used in compressors for refrigeration and air conditioning experience vibration and noise due to radial exciting forces caused by magnetic flux, which existing technologies have not adequately addressed.
Innovation Solution
The design incorporates a rotor core with magnet receiving holes featuring slits and space portions between permanent magnets, where the circumferential width of the space portions is less than or equal to the width of the opposing slits, to reduce radial exciting forces by increasing magnetic resistance and flux density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If permanent magnets are inserted into magnet receiving holes in the rotor core, then the motor generates electromagnetic force to drive the compressor, but lubricating oil enters the magnet receiving holes causing permanent magnets to move easily, generating vibration and noise
Solution Approach 1:
Each magnet receiving hole is divided into multiple segments by forming slits between the outer peripheral surface and the outer-side defining line. These slits create magnetic resistance barriers that segment the magnetic flux path, preventing the magnetic flux from directly acting on the permanent magnets in the radial direction, thereby reducing vibration and noise while maintaining electromagnetic driving force.
Solution Approach 2:
The patent applies different structural characteristics to different locations: the slits are positioned at specific locations between the outer peripheral surface and the magnet receiving hole, creating localized magnetic resistance zones. This local modification allows the magnetic flux to be controlled in specific areas, reducing the radial exciting force on permanent magnets without affecting the overall electromagnetic force generation.
2Object-affected harmful factors
If slits are formed in the rotor core between outer peripheral surface and magnet receiving holes, then magnetic resistance increases to reduce radial exciting force, but magnetic flux flow in q-axis direction may be affected
Solution Approach 1:
The slits are formed in a specific dimensional configuration - radially between the outer peripheral surface and the magnet receiving hole, but not extending fully into the magnet receiving hole. This dimensional positioning creates magnetic resistance in the radial direction (blocking the harmful q-axis flux) while leaving the axial and tangential flux paths intact, thus maintaining the necessary magnetic flux flow for power generation.
3Object-affected harmful factors
If space portions are formed between permanent magnets with width W1 less than or equal to slit width W2, then magnetic resistance is increased to suppress radial exciting force, but device complexity increases
Solution Approach 1:
The space portions between permanent magnets are designed with width W1 that is less than or equal to the slit width W2. This partial spacing approach provides sufficient magnetic resistance to reduce radial exciting force and vibration, while avoiding excessive spacing that would unnecessarily increase device complexity. The relationship W1≤W2 ensures adequate vibration suppression without over-engineering the structure.
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 configuration effectively suppresses vibration and noise by reducing radial exciting forces and enhancing magnetic flux density, while maintaining cost-effectiveness by using equally sized or strategically sized permanent magnets.
Implementation Method 1
the magnetic resistance at a radially outer portion of the magnet receiving hole is small, and hence a magnetic flux in a direction of a so-called q-axis
Implementation Method 2
as a direct factor, an electromagnetic force from a stator acts on each of the permanent magnets so that the permanent magnets may be moved inside the magnet receiving holes
Implementation Method 3
a rotor rotatably arranged so as to be opposed to the stator
Data Source
AI summary
An interior permanent magnet motor includes a stator and a rotor. The rotor includes a rotor core having a plurality of magnet receiving holes, and a plurality of permanent magnets are received in each of the magnet receiving holes. A plurality of slits are formed at a part between an outer peripheral surface of the rotor and an outer-side defining line of the each of the magnet receiving holes. At least one space portion is secured between the plurality of permanent magnets, and the space portion is opposed to any one of the plurality of slits in a direction parallel to a magnetic pole center line.