Induction motor emulation for variable frequency drives testing

Abstract

This paper presents a method employing a simple three-phase transformer connected to a three-phase AC variable load for emulating a standard three phase AC induction motor. Such an emulator could be used for variable frequency drive testing but eliminates any moving parts for higher reliability, reduces audible noise, and eliminates high-cost dynamometers. The method utilizes the concept of assuming that the induction machine is a "rotating transformer." To validate the emulator behavior, a simulation for a line-fed machine and a line fed three-phase transformer with a three-phase variable load is performed. Experimental verification of the inverter-fed machine and transformer are also presented and show excellent emulation capabilities of motor behavior at various slip values.