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Breakthroughs in Flat Wire Motor Winding Technology for High-Voltage Platforms

In the dynamic landscape of high-voltage platforms, encompassing the entirety of a vehicle's battery system, charging infrastructure, and electric drive mechanisms, there's an increasing demand for innovations that prioritize high efficiency, lightweight construction, and cost-effectiveness. The performance of the motor, as the central element of the electric propulsion system, profoundly influences the overall capabilities of the vehicle. Within the framework of 800V architectures, motor design diverges from that of traditional low-voltage platforms, necessitating advancements in electric propulsion systems to achieve heightened efficiency, reduced weight, and optimized cost structures. Against this backdrop, the adoption of flat wire winding technology in motors has garnered significant interest among suppliers and automotive manufacturers.

Forms of Flat Wire Motor Winding


Classified by their manufacturing methods, flat wire motors primarily employ three winding techniques:


  1. Hair-pin Winding: This method involves shaping flat copper wires into hairpin-like forms, with one end serving as the welding point. Although more intricate in manufacturing, hair-pin winding reduces copper consumption compared to alternative methods, thereby enhancing motor efficiency by minimizing welding points.

  2. I-pin Winding: In this axial embedding winding technique, flat conductors are directly embedded into the core slots, with the ends twisted and welded. While simpler in manufacturing, I-pin winding results in higher copper consumption and reduced efficiency due to increased temperature caused by welding points.

  3. Continuous Wave Winding: This welding-free, highly flexible design presents challenges in maintaining symmetry, leading to differences in back electromotive force, resistance, and inductance. Asymmetry in winding branches diminishes motor performance and may cause localized overheating.



Innovations in Flat Wire Motor Winding


To address challenges associated with traditional flat wire winding methods, pioneers like DENSO from Japan have introduced advancements:


  • DENSO employs a stepped end design to minimize height restrictions caused by triangular end structures typical in hair-pin winding. This reduces the winding's bend radius and facilitates insulation.

  • Polymer insulation material is applied atop flat wire insulation to ensure insulation requirements are met, even if coils come into contact, enhancing reliability.



Motor Cooling and Heat Dissipation Research


As high-voltage platforms and flat wire winding technology propel motors towards higher power and speeds, effective cooling mechanisms become paramount. While air cooling offers limited heat dissipation capabilities, water-cooled and oil-cooled systems present promising solutions.


  • Water-cooled systems adapt traditional engine cooling approaches but face challenges due to water's properties such as conductivity and low boiling point.

  • Oil cooling emerges as a primary method due to its non-conductive and non-magnetic properties. It directly cools motor components while offering lubrication, promising efficient heat dissipation.


Future Directions


Emerging technologies such as the "Automotive Drive Motor Flat Wire Winding Shift Technology" proposed by Harbin University of Science and Technology aim to revolutionize motor winding processes, reducing losses and improving efficiency and power density. Such advancements promise to meet the escalating demands for lightweight, cost-effective, and reliable drive motors in the realm of new energy vehicles.

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