Influence of PWM switching frequency and modulation index on the iron losses and performance of slot-less permanent magnet motors

This paper investigates the influence of switching frequency and modulation index on the iron losses in thin silicon-iron (SiFe) lamination sheets of a small slot-less permanent magnet synchronous machine (PMSM). First, measurements are conducted on one welded and one non-welded stator core for switching frequencies between 1 kHz and 20 kHz and modulation indices of 0.4, 0.7, and 0.9, keeping constant fundamental flux density peak values. The obtained measurement data is afterwards used in finite element method (FEM) simulations to investigate the switching frequency influence on the performance of the PMSM.