Distributed Armature Winding for High Pole Count DC Machines
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Solution Overview
Problem
DC rotating electrical machines with electronic commutation face limitations in the number of commutation events per pole-pair, which is typically equal to the number of coils per pole-pair, leading to inefficiencies in high-voltage, low-current operations, especially in large-diameter, multi-pole generators for wind turbine applications.
Innovation Solution
A distributed connection armature winding with non-integer slots per pole-pair and coils placed in pairs with phase angles that form multiple phases, allowing for significantly more commutation events per pole-pair by connecting coils in series and spacing them further apart than the number of slots per pole-pair, enabling increased phase angles and commutation events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of coils per pole-pair is increased to increase the number of commutation events per pole-pair, then the number of commutation events increases, but the device complexity and copper loss increase
Solution Approach 1:
The invention divides the armature winding into multiple independent circuits, where each circuit contains a subset of coils that can be commutated independently. This segmentation allows the total number of commutation events to exceed the number of coils per pole-pair, as multiple circuits can undergo commutation simultaneously or in rapid succession, thereby resolving the contradiction between increasing commutation events and maintaining device complexity.
Solution Approach 2:
The invention introduces a temporal dimension to the commutation process by implementing multi-circuit windings with different phase angles. Instead of simply adding more coils in space, the system utilizes time-multiplexed commutation across multiple circuits, where each circuit contributes to the total commutation events. This dimensional transition from spatial to temporal organization enables higher commutation rates without proportionally increasing physical complexity.
2Ease of manufacture
If the number of poles is increased to reduce the number of slots per pole-pair and simplify construction, then construction is simplified, but the number of commutation events per pole-pair is limited
Solution Approach 1:
The invention implements dynamic multi-circuit windings where the active circuit can be switched or modulated during operation. This dynamic configuration allows the system to maintain a simple physical structure with few slots per pole-pair while achieving high commutation event rates through temporal multiplexing of multiple circuits, effectively decoupling construction simplicity from commutation performance.
3Quantity of substance
If coils are placed closer together to reduce the number of winding slots, then the number of slots per pole-pair decreases, but the phase angle distribution and commutation performance deteriorate
Solution Approach 1:
The invention segments the winding slots into multiple circuits, where each circuit maintains its own phase angle distribution characteristics. This segmentation allows the overall system to use fewer total slots while each circuit preserves adequate phase angle spacing for reliable commutation, as the multi-circuit architecture compensates for the reduced slot count through parallel commutation paths.
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 enhances the number of commutation events per pole-pair, reducing torque ripple and improving operational efficiency in large-diameter, multi-pole generators, allowing for more phases than coils per pole-pair, thus optimizing performance in high-voltage, low-current conditions.
Implementation Method 1
A DC electrical machine comprises field means for providing a magnetic field... a DC armature winding that in use interacts with the magnetic field
Data Source
AI summary
The present invention relates to armature windings for DC electrical machines, and in particular to those that use electronic commutation and have relatively few slots per pole-pair. The armature windings are particularly well suited for use with rotating DC electrical machines that have a large diameter and a large number of poles such as those that might be directly coupled to the turbine blade assembly of a wind turbine. The armature winding is arranged in relation to the magnetic field generated by a field winding or by permanent magnets such that a number of commutation events during the time taken for the relative movement between the armature and the field system of one pole-pair is much larger than the number of coils per pole-pair.