This paper investigates the influence of PWM-induced current harmonics on the electromagnetic performance of slotless PMSMs. The operation principle of PWM current harmonics is analyzed from a mathematical model of slotless PMSMs. To analyze the current harmonic, motor control simulations are implemented to obtain current waveforms under PWM operation. These current waveforms are applied in finite element analysis to evaluate the electromagnetic performance. Since PWM current harmonics are dependent on both switching frequency and inductance, the resulting copper loss, iron loss, AC loss, and torque ripple are analyzed with respect to these parameters. As a result, as both switching frequency and inductance increase, the electromagnetic performance, including loss and torque characteristics, is improved. The results provide a comprehensive evaluation of the electromagnetic performance of slotless PMSMs under PWM operation, highlighting the role of current harmonics.
Koo et al. (2026) studied this question.