A feedforward approach to the dynamic emulation of mechanical loads

A simple practical approach to the testing of variable speed and torque drives with the application of the dynamic emulation of mechanical loads is presented. Both, linear and non-linear dynamics can be applied. The experimental system consists of the drive under test, which is mechanically connected to the active loading system. The emulation procedure is performed by the closed-loop calculation of the torque, applied by the load machine, in such a manner that the input/output behavior of the experimental system resembles the one of the drive under test propelling the emulated load. A simple feedforward scheme, combined with a feedback controller, is used. In contrast to existing references the method is simple and requires no torque measurement equipment. Also the influence of the nonlinear dynamics of the experimental system is discussed. The method can be used for the evaluation of the control algorithms, regardless the control and estimation methods used. The applied load machine is assumed to be torque-controlled with high precision. An induction motor is used as a drive machine and a BLDC machine is used as a load machine. Algorithms are developed with the use of Matlab/Simulink and experiments are executed with the use of the dSPACE system.