Harmonic Compensation of a Power-Hardware-in-the-Loop Based Emulator for Induction Machines

Power-hardware-in-the-loop (PHIL)-based machine emulator systems use controlled power converters to mimic the behavior of an electric machine. In this article, a PHIL-based machine emulation system is proposed for grid-tied three-phase induction machines (IM). Typically, a switched voltage source inverter (VSI) is employed as an emulator converter in the motor emulation system. However, the VSI introduces various harmonics into the motor emulation system. These harmonics are mainly attributed to dead time, switching components, and control signals. These harmonics deteriorate motor emulation accuracy. Thus, it is important to investigate and compensate for emulator converter harmonics in motor emulation systems. As an important source of these harmonics is dead time, a detailed analysis of the dead time effect on motor emulation will be presented first. Subsequently, a novel artificial neural network (ANN)-based harmonic compensation technique is developed to ensure the mitigation of harmonics in the emulated motor currents. The proposed ANN-based intelligent harmonic compensator leads to the improvement of motor emulation accuracy. Experimental results are obtained from the emulator system and a 5 hp squirrel cage induction motor to validate the proposed emulator with harmonic compensation.