Hairpin Winding Electric Machine Balanced Circuits
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Solution Overview
Problem
Designing electric machines with hairpin windings poses challenges in matching the torque-speed curve and creating balanced parallel circuits due to limitations in the number and size of conductors that can be fit in a single slot, as well as complex connections required for hairpin windings, which differ significantly from conventional stranded windings.
Innovation Solution
The electric machine employs a stator core with circumferentially arranged slots and radial pin positions, featuring interconnected hairpin windings in multiple phases without jumpers, utilizing short-pitch and long-pitch pins to form continuous conductors across radial layers, ensuring balanced and efficient torque production.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional stranded windings are used, then the connection process is simpler, but the manufacturing precision and efficiency are reduced due to the inability to match torque-speed curve and create balanced parallel circuits
Solution Approach 1:
The stator core is divided into multiple slots with radial pin positions arranged in adjacent pairs to define radial layers. Hairpin windings are segmented into multiple paths (first path, second path, third path, fourth path) that are disposed in odd and even slots alternately, allowing independent optimization of each path while maintaining overall balance.
Solution Approach 2:
Multiple hairpin paths are interconnected through neutral bridges to form balanced parallel circuits. The first and second paths are connected via a first neutral bridge, while the third and fourth paths are connected via a second neutral bridge, merging the paths into balanced circuit configurations that enable precise torque-speed curve matching.
2Power
If more conductors are placed in a single slot to improve torque production, then the torque output increases, but the manufacturing precision deteriorates due to difficulty in fitting and positioning
Solution Approach 1:
Instead of increasing conductor quantity in a single slot, the solution transitions to a multi-dimensional arrangement where conductors are distributed across multiple radial layers and alternating odd/even slots. This spatial distribution maintains positioning precision while achieving the desired torque output through balanced parallel circuits.
3Ease of manufacture
If jumpers are used to connect hairpin windings, then the winding configuration is simpler, but the manufacturing cost and complexity increase
Solution Approach 1:
The jumper connections are extracted and replaced with direct interconnections between hairpin paths. The neutral bridges serve as connection points that eliminate the need for separate jumper components, simplifying the overall connection structure while maintaining manufacturing ease.
4Power
If complex connections are used to achieve balanced parallel circuits, then the torque-speed curve matching improves, but the productivity decreases due to increased manufacturing complexity
Solution Approach 1:
The hairpin windings are pre-configured into specific paths with defined interconnections before assembly. The neutral bridges are positioned in advance to connect the paths, allowing the balanced parallel circuits to be formed systematically during assembly, thereby improving productivity despite the complexity of the final configuration.
Data Source
AI summary
An electric machine includes a stator core defining circumferentially arranged slots alternating between odd and even slots. Each slot has radial pin positions arranged in adjacent pairs to define radial layers. A hairpin winding includes a first path of interconnected hairpins that is disposed in the stator core such that, for each of the radial layers, the first path is disposed in the odd slots and the even slots a same number of times.