Two-Phase Synchronous Motor Stator for Lower Demagnetization Loss
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Solution Overview
Problem
Existing two-phase synchronous electric motors for dishwashers suffer from high demagnetization effects and Joule losses due to the physical limitations of SMC materials, leading to increased surface area requirements, higher copper wire usage, and elevated pick-up voltages, which compromise performance and cost-effectiveness.
Innovation Solution
A two-phase synchronous electric motor design featuring a permanent-magnet rotor with a core lamination-pack stator, where each pole piece's free end portion is structurally independent and can be connected by mortising, with core laminations extending in planes parallel to the rotation axis, and a phase displacement capacitor to optimize magnetic field generation and reduce demagnetization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If SMC material is used for the core and pole piece end, then manufacturing ease and structural integration are improved, but demagnetization effect increases and flux distribution becomes concentrated in the core central area
Solution Approach 1:
The pole piece is divided into two separate components: a core made of SMC material and a free end portion made of a different material (such as electrical steel or another ferromagnetic material). This segmentation allows each part to be optimized independently - the SMC core provides manufacturing ease and structural integration, while the alternative material free end portion reduces demagnetization effect and improves flux distribution across the entire pole piece height.
2Ease of manufacture
If SMC material is used for the core, then manufacturing is simplified, but the surface area must be increased by at least 25% to achieve the same magnetic conditions
Solution Approach 1:
The pole piece uses a composite structure combining SMC material for the core with a different ferromagnetic material for the free end portion. This composite approach leverages the manufacturing advantages of SMC while compensating for its inferior magnetic properties in the free end region, thereby achieving the desired magnetic conditions without increasing the overall surface area by 25% or more.
3Quantity of substance
If cylindrical core is used to decrease copper wire quantity, then material usage is reduced, but negative demagnetization effects occur due to poor electromagnet linkage
Solution Approach 1:
The free end portion of the pole piece is constructed with specific local characteristics (different material composition and optimized geometry) to enhance electromagnet linkage in the critical region where magnetic flux interacts with the rotor. This localized optimization ensures adequate magnetic coupling without requiring excessive copper wire in the windings.
4Device complexity
If core and pole piece end are made enbloc in SMC material, then assembly is simplified, but height difference between core and pole piece end cannot be effectively utilized
Solution Approach 1:
The pole piece is segmented into a core and a free end portion that are separately manufactured and then assembled together. This segmentation enables effective utilization of the height difference between the core and the free end portion, allowing the free end to extend sufficiently toward the rotor for optimal magnetic coupling while the core provides structural support. The separate components are joined through mechanical means such as interference fits, rivets, or welding.
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
The motor achieves significant reduction in demagnetization and Joule losses, improved electromagnetic performance, and cost-effectiveness by distributing flux effectively and allowing for the use of aluminum windings, which reduce weight and thermal losses.
Implementation Method 1
a permanent-magnet rotor (2) and a core lamination-pack stator (4), wherein a first (6) and second (7) pairs of pole pieces (8) define a housing/rotation seat (5) for said rotor (2)
Implementation Method 2
each pole piece (8) comprising a core (9), having an end (14) being associated to said core lamination pack (10) and an opposite free end portion (11) facing said housing/rotation seat (5)
Implementation Method 3
a coil (12) for a stator winding on a corresponding support (13) being wedged on said core (9)
Data Source
Figure 1
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AI summary
The present invention relates to a two-phase synchronous electric motor (1), comprising a permanent-magnet rotor (2), rotating around a respective rotation axis (X), and a core lamination-pack (10) stator (4), wherein first (6) and second (7) pairs of pole pieces (8) define a housing/rotation seat (5) for said rotor (2) and wherein each pole piece (8) comprises a core (9), having an end associated to the core lamination pack (10) and a free end portion (11), facing the rotor (2) housing/rotation seat (5), a coil (12) on a respective support (13) wedged on said core (9). Advantageously, at least the free end portion (11) of the core (9) of each pole piece (8) comprises a core lamination pack (15) extending in respective parallel planes to the rotation axis (X) of the permanent-magnet rotor (2). Advantageously, the core laminations (15) have a variable length to form a surface of said free end portion (11) of the core (9) of each pole piece (8) being concave in the axial direction and partially wrapping the rotor (2). The particular structure of the stator (4) can be advantageously matched to the double-joint kinematic coupling between the rotor (2) and the load (31) and to the phase displacement capacitor (C) expedient between the windings associated to one of the pole piece pairs.