Distributed Winding Arrangement for Electric Motor
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Solution Overview
Problem
Traditional brush commutated electric motors experience significant brush arcing and electromagnetic interference due to the inherent poorer magnetic commutation of the second coil, leading to accelerated brush wear and increased size and cost.
Innovation Solution
A distributed winding arrangement with multiple coils and subcoils wound in specific patterns to align magnetic axes with commutator bars, reducing the number of commutator bars and thus the commutator size, while maintaining improved commutation efficiency by ensuring all coils' commutation zones are within the magnetic neutral zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional two-coil-per-slot winding arrangement is used, then the motor structure is simple, but brush arcing increases and commutation efficiency deteriorates
Solution Approach 1:
The patent segments the traditional two-coil-per-slot arrangement into a distributed winding system with multiple coils (at least three coils per pole) arranged across multiple slots. Each coil is assigned to specific slots with predetermined angular positions, dividing the commutation task across multiple segments to reduce arcing at any single brush-commutator interface.
Solution Approach 2:
The patent assigns different angular positions to the magnetic axes of different coils relative to their associated commutator bars. This local optimization ensures that each coil's commutation occurs at its optimal angular position within the magnetic neutral zone, improving overall commutation efficiency while reducing brush arcing.
2Reliability
If distributed winding arrangement with multiple coils is used, then brush arcing is reduced, but the number of commutator bars increases and motor size increases
Solution Approach 1:
The patent establishes a specific mathematical relationship between the number of coils and the number of commutator bars, where the number of commutator bars is an integer greater than the number of coils but less than twice the number of coils. This parameter optimization reduces the commutator size compared to traditional designs while maintaining the benefits of distributed winding.
Solution Approach 2:
The patent uses at least three coils per pole (excessive action compared to traditional two coils) to ensure all coils' commutation zones are within the magnetic neutral zone, but optimizes the commutator bar count to be less than twice the coil count, avoiding the excessive commutator size that would normally result from such a configuration.
3Reliability
If distributed winding arrangement is used to improve commutation, then brush arcing is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent creates a universal winding arrangement that can be applied to motors with different numbers of poles and slots by maintaining the fundamental relationship of at least three coils per pole with specific angular positioning. This multi-functional design approach allows the same basic principle to optimize commutation across various motor configurations without requiring completely different winding patterns for each case.
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 brush arcing and electromagnetic interference, improves commutation efficiency, and decreases the size and cost of electric motors by eliminating the need for additional components to attenuate EMI.
Implementation Method 1
an armature having a plurality of coils wound in slots formed in the lamination stack of the armature
Implementation Method 2
the first coil and the first subcoil portion of the second coil are wound with different number of winding turns so that a resultant magnetic axis of the first coil lies at a predetermined angular position
Data Source
AI summary
A distributed winding arrangement for an electric motor is provided that reduces brush arcing while reducing the size of the commutator. The electric motor is comprised generally of an armature having a plurality of spaced apart posts defining a plurality of spaced apart winding slots; a stator disposed coaxially with the armature; and a commutator having a plurality of commutator bars, where the number of commutator bars is an integer greater than the number of winding slots but less than twice the number of winding slots provided by the armature.