This page shows some of the loss curves and efficiency curves for the operating region of the motor.

An example motor is considered and solved using FEA for different speed and torque points to predict the losses using Bertotti loss model and LS loss model. The bertotti losses are used along with the magnet losses and the copper losses to predict the input and hence the efficiency of the motor.

LS Loss model was just plotted to be able to compare with the bertotti losses.

Bertotti losses can be split into hysteresis losses, eddy losses and excess losses.

In each of the following images:

  • the dark-thick line represents the speed-torque characteristic curve.
  • the black + dots represent the operating points of the motor when used as a traction motor on a certain vehicle with a certain drive cycle.
  • the blue * dot represent the peak of the corresponding map.

The following output map can be generated from the knowledge of speed and torque values. map_output

The first component of bertotti losses in the rotor - hysteresis losses map_bertotti_rotor_hyst

The second component of bertotti losses in the rotor - eddy losses map_bertotti_rotor_eddy

The third component of bertotti losses in the rotor - excess losses map_bertotti_rotor_excess

Total bertotti losses in the rotor map_bertotti_rotor

LS losses in the rotor - an equivalent of Bertotti losses, but calculated differently map_LSLoss_rotor

The first component of bertotti losses in the stator - hysteresis losses map_bertotti_stator_hyst

The second component of bertotti losses in the stator - eddy losses map_bertotti_stator_eddy

The third component of bertotti losses in the stator - excess losses map_bertotti_stator_excess

Total bertotti losses in the stator map_bertotti_stator

LS losses in the stator - an equivalent of Bertotti losses, but calculated differently map_LSLoss_stator

Losses in the magnet map_magnetloss

Copper losses map_i2rloss

Total losses map_loss

Output + Losses = input map_input

Predicted input map_efficiency

Now, the above efficiency map assumes a default material, and certain ideal processes. In reality, the losses may be more than predicted. It is recommended to use a factor of safety for the losses estimated while calculating the efficiencies.