Switching Frequency Impact on Permanent Magnet Motors Drive System for Electric Actuation Applications

This paper investigates the harmonic losses and torque ripple of a surface permanent magnet (SPM) motor driven by pulsewidth-modulated inverter for a wide range of switching frequencies (SFs), using a 2-D nonlinear time stepping finite-element model, including strand conductors proximity effect, coupled with an appropriate external electric circuit. Such a method enables the estimation of torque ripple as well as the accurate prediction of the eddy current losses in the windings, lamination core, and PMs, respectively. Moreover, the total power losses of the inverter are calculated via analytical techniques. The analysis undertaken proposes an optimum SF, in terms of overall drive system efficiency and torque quality, considering multiple operating conditions. The simulated results are validated by measurements on a prototype SPM actuator, illustrating that the SF plays an important role on SPM motor drive applications.