FEM–PWM Circuit Model of a Brushless DC Motor Using COMSOL

Abstract

This paper presents a computer-aided-design (CAD) of a Brushless DC motor (BLDC) by coupling a Finite Element Method (FEM) based electromagnetic field model with the electric circuit equations of the PWM, using COMSOL Multiphysics professional software. The transistors are simulated by means of controlled switches, while free wheel diodes are modeled using COMSOL library. The field-circuit model is used to analyze the real phase current variation at different rotor speeds, after a prior motor optimization based on steady-state electromagnetic models and numerical determination of motor’s back EMF.Several practical aspects regarding numerical model built in COMSOL Multiphysics v5.3 are also presented. Brushless DC motor (BLDC), Pulse Width