IPM Rotor Voids for Iron Loss Reduction
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Solution Overview
Problem
In IPM type motors, widening the gap between the stator and rotor core reduces magnetic flux density and torque constant, leading to increased iron loss and decreased motor efficiency at low loads.
Innovation Solution
A rotor design featuring plate-shaped magnets with intersecting magnetic pole faces and voids in the rotor core, which are in contact with the magnetic pole faces closer to the central axis, helps maintain torque constant while reducing iron loss without increasing the gap between the stator and rotor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the gap between the stator core and the rotor core is widened, then iron loss at low load can be suppressed, but the torque constant decreases
Solution Approach 1:
The patent introduces voids at specific locations within the rotor core, closer to the central axis, rather than uniformly modifying the entire rotor structure. This localized modification allows the magnetic flux density to be optimized in specific regions, reducing iron loss while maintaining adequate flux density in other regions to preserve torque constant.
Solution Approach 2:
The rotor core is segmented into different functional regions by introducing multiple voids at different radial positions. The regions closer to the central axis contain voids to reduce iron loss, while the outer regions maintain higher magnetic flux density to preserve torque generation capability.
2Use of energy by moving object
If the gap between the stator core and the rotor core is widened, then magnetic flux density becomes lower, but motor inductance and torque decrease
Solution Approach 1:
The patent modifies the magnetic circuit parameters by introducing voids with specific dimensions and positions within the rotor core. This changes the magnetic flux distribution and density patterns, allowing optimization of energy efficiency while maintaining adequate motor inductance through careful control of void size and placement.
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 design effectively reduces iron loss and maintains torque constant, enhancing motor efficiency without widening the gap between the stator and rotor, as demonstrated by simulation results showing favorable iron loss and torque reduction ratios.
Implementation Method 1
a plurality of plate-shaped magnets forming multiple poles, each of the magnets being arranged in the rotor core with a pair of magnetic pole faces thereof being positioned in a direction intersecting with the radial direction of the rotor core
Implementation Method 2
when the gap between the stator (stator core) and the rotor (rotor core) is widened, the magnetic flux density in the stator and the rotor becomes lower, so that iron loss at low load can be suppressed
Data Source
AI summary
A rotor includes: a rotor core; a plurality of plate-shaped magnets forming multiple poles, each arranged in the rotor core with a pair of magnetic pole faces thereof being positioned in a direction intersecting with the radial direction of the rotor core; and a plurality of voids formed in the rotor core, each arranged in contact with the magnetic pole face that is located on a side closer to the central axis of the rotor core, of each of the magnets forming multiple poles.