Design of test rig to measure electromagnetic forces and torque of a dual three-phase induction motor

When asymmetrically supplied, the dual three-phase motors produce electromagnetic forces on the rotor through the unbalance of the magnetic fields in the air gap. This paper presents the design and prototyping of a novel setup for simultaneously measuring the electromagnetic torque and forces acting on the rotor of a dual three-phase induction machine under asymmetric operating conditions. A three-dimensional FEM model is developed to assess the operational stability of the prototype machine across a wide range of speeds. The design of the proposed setup along with its working principle as well as the results of measurements for the torque and forces and their comparison with the simulation results are presented. The study shows that the setup can simultaneously measure the forces and torque as predicted by the simulations. The proposed setup will be used for the development and validation of different control strategies in view of rotor dynamics stabilization.