Claw-Pole Rotor Permanent Magnet Electric Machine Weight Reduction
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Solution Overview
Problem
Existing electrical machines have a high copper mass and weight in their stator and excitation windings, which hinders the reduction of weight while maintaining efficiency and power output, and limits power density.
Innovation Solution
The design incorporates a claw-pole rotor with alternating claw poles and a permanent magnetic device, optimizing the magnetic circuit geometry and using a fan to enhance cooling, which reduces copper mass and increases power density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If traditional excitation windings and stator windings are used, then the electrical machine can generate sufficient power, but the copper mass and weight become excessively high
Solution Approach 1:
The patent changes the fundamental parameter of magnetic field generation from electromagnetic induction in windings to direct permanent magnet fields. This parameter change eliminates the need for copper excitation windings entirely, reducing copper mass while maintaining power output through optimized permanent magnet arrangements in the claw-pole rotor structure
Solution Approach 2:
The patent extracts and removes the excitation winding system from the electrical machine design. By using permanent magnets directly in the claw poles, the excitation function is separated from the stator windings, eliminating the heavy copper excitation windings while preserving the necessary magnetic field generation for power output
2Weight of moving object
If copper mass is reduced to decrease weight, then weight decreases, but efficiency and power output may be compromised
Solution Approach 1:
The patent fundamentally changes the magnetic field generation mechanism from winding-based to permanent magnet-based, which allows weight reduction without compromising power output. The optimized claw-pole geometry and permanent magnet arrangement ensure sufficient magnetic flux for maintaining efficiency and power generation capability
Solution Approach 2:
The patent employs composite construction combining permanent magnets, magnetic conductive materials in the claw poles, and optimized stator structures. This composite approach achieves high power density and efficiency with reduced copper content by leveraging the complementary properties of different materials in the magnetic circuit
3Weight of moving object
If copper mass is reduced to decrease weight, then weight decreases, but power density remains limited
Solution Approach 1:
The patent changes the magnetic field source parameter to permanent magnets, which enables higher power density in a more compact, lighter structure. The optimized claw-pole design with permanent magnets creates a more efficient magnetic circuit that increases power output per unit volume and weight
Solution Approach 2:
The patent optimizes the three-dimensional arrangement of permanent magnets and magnetic flux paths in the claw-pole structure. By carefully designing the spatial distribution and geometry of magnetic components, the patent achieves enhanced power density through improved magnetic flux utilization in the radial and axial dimensions
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 approach significantly reduces the copper mass and weight of the electrical machine, maintaining efficiency and power output while enhancing power density.
Implementation Method 1
differently polarized excitation poles or claw poles arranged adjacent to the circumference of the rotor generating a stator voltage in a stator winding of the stator during rotary movement
Implementation Method 2
a fan (30) which covers a majority of the end winding (45) in a view in the direction of rotation of the rotor (20), wherein the fan (30) is arranged radially inside the end winding (45)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to an electric machine (10) comprising a stator (16) that has a stator core (17). Said core has a substantially cylindrical opening (60) having a central axis (63), and the opening (60) accommodates a rotor (20). The stator core (17) has an axial length (L17a) and said core (17) holds a stator winding (18) together with the rotor (20) which has a rotational axis (66). The rotor (20) has an axial end face (69), on which a fan (30) with fan blades (72) is located and is non-rotatably connected to the rotor (20). The rotor (20) has an electromagnetically excitable path (75) having a pole shank (78), a respective pole plate (22, 23) adjoining each axially rotational end (80, 82) of said shank. Claw poles (24) having a north polarity extend from one pole plate (22) and claw poles (25) having a south polarity extend from the other pole plate (23), said claw poles (24) and (25) alternating between north and south polarities around the periphery of the rotor (20). The rotor (20) has a gap (21) with a longitudinal direction (86) between two neighbouring claw poles (24, 25) of opposite polarity, a permanent magnet system (88) being provided in the gap (21) between the two claw poles (24, 25). The permanent magnet system (88) has a length (L88) in the longitudinal direction (86) of the gap (21). The rotor comprises a pole shank (78) located radially inside the claw poles (24, 25), said shank having an axially rotational length (L78), and the ratio of the length (L88) of the permanent magnet system (88) to the axially rotational length (L78) of the pole shank (78) is greater than 1.3.