In this paper, a loss-minimizing strategy is proposed
for induction motor drives to ensure maximum efficiency
operation for a given torque demand. The proposed strategy
directly regulates the machine stator flux according to the
desired torque, using an optimal stator flux reference.
Therefore, the proposed strategy is suitable for motor control
schemes that are based on direct flux regulation, such as direct
torque control or direct flux vector control. The maximum
efficiency per torque (MEPT) stator flux map is computed offline
using the traditional no-load and short-circuit tests’ data.
An iron loss model based on the stator flux and frequency is
also proposed for the calibration of the machine loss model and
also for on-line monitoring of the iron losses during motor
operation. The proposed MEPT strategy has been validated on
a 2.2 kW induction machine and the motor efficiency has been
measured for different speed values and variable load
conditions. The experimental results confirm the effectiveness
of the proposed solution.