Improving the maximum torque per ampere in a BLDC motor accounting for transient and continuous operation using thermal boundary conditions

This paper investigates the impact on power density of a BLDC motor using different control strategies. The simulations are carried out using 2D electromechanical FEM calculations, including the frequency converter supply. The maximum steady state output power is determined using thermal FEM calculations. The obtained results shows that an increase of 5.9% in output power can be obtained by running a BLDC motor with sinusoidal currents at rated operation instead of using BLDC currents. In addition, an increase of 18% peak torque can be obtained at rated speed operation when sinusoidal feeding is used instead of BLDC supply. The result is verified with measurements showing a close correlation to the calculation, were 6.5% increase of output power was obtained at rated operation.