Stress Limitation in the Coil Heads of Electrical Machines Using Optimized Winding Solutions

The supply voltage of electrical machines tends to be increased, both in industrial applications and in electro-mobility uses. As a result, the Electrical Insulation System (EIS) must be adapted accordingly to these constraints. Defining the EIS requires knowing accurately the critical voltage levels that appear in the motor. For a concentrated winding fed by a Variable Speed Drive (VSD), the highest stresses occur in the slots. However, for distributed windings, as in conventional induction or synchronous machines, the most critical stresses appear in the coil heads, whether they are supplied by an inverter or by the grid. The objective of this study is to investigate possible solutions able to limit these constraints.