Efficiency and Loss Mapping of AC Motors using Advanced Testing Tools

The efficiency and loss maps represent an important tool to evaluate an electrical motor drive. The efficiency maps are usually computed using finite element analysis or equivalent circuits that take into account the motor losses. However, these methods need to be compared with efficiency maps that must be experimentally obtained using calibrated instruments. The main problem is how to implement an automated procedure that must obtain the motor or drive efficiency for all operating points. This paper describes an efficiency and loss mapping procedure that has been applied for a 5.3 kW three-phase internal permanent magnet machine prototype for traction applications, but it can be used for any AC machine with inverter supply. All measurements have been performed with an advanced data recorder instrument. The efficiency and loss maps are calculated after the test with a post-processing procedure that can provide all information regarding the motor exploitation, including current, voltage and flux vector trajectories in (d,q) rotor frame.