Review and assessment of automated coil forming methods

Work Package Leader: Prof. Davide Barater


To Identify and evaluate innovative high precision coil forming technologies and methodologies such as hair-pin technology. To consider how the enamelled wire is aligned, stripped of its insulation, formed and insertion tips produced.

Compare technologies in terms of number of joints, ability to reduce AC losses through adoption of litz/laminated/Roebel conductors. To Assess and down select technologies against project aims.


This work package will include a detailed review of coil forming technologies and methodologies.

It is clear from the state of the art section that the applicants have already conducted a preliminary investigation about the subject. However, the analysis will be further expanded, targeting in particular preformed conductors with rectangular cross sections, such as hair-pin technology (see section, to consider how the different types of wires are aligned, stripped of its insulation, formed and insertion tips produced.

The performance of different type of wires will be compared in term of reduced AC losses, improved fill factor and thermal conductivity, ability to withstand high dv/dt switching, and reduction of the end-winding region. The investigation will target in particular litz/laminated/Roebel conductors and will be conducted considering both analytical approach and finite element FEM simulations. Due to the complex nature of the phenomena, computational tools to analyze the interaction between electromagnetic thermo-fluid dynamics phenomena will be employed. 

The down selection of the technology will consider a matrix of parameters, such as:

  • number of joints, 
  • joining processes (laser etc.)
  • enhanced slot fill factor 
  • improved thermal conductivity
  • reduced AC losses at high-frequency operations 
  • shorter end windings
  • improved reliability
  • mechanical stiffness and manufacturing properties of the proposed windings 
  • maturity and availability of the proposed windings
  • limit of the state of the art and possible future developments

As reference system, two types of stators will be taken into account with different geometrical factors: one with large diameter and short longitudinal length, and another with longitudinal length prominent compared to the stator outer diameter. The physical dimensions of the 2 stators will be provided by the TM.  

UniMore will lead the activity by performing the review and assessment of the state of the art. 

Even if a specific task is not assigned to Coppering in this WP. Coppering will assist UniMore in the process, providing its expertise on automatic winding production systems, if necessity arises.This activity will set the basis for the buildout of the programmable coil forming tool and joining method that will be developed in the subsequent WPs