Inherently Robust Loss Model Controller for Energy Efficient Operation of Indirect Rotor Field Oriented Induction Motor Drives

This article introduces a robust energy efficient control method for induction motor (IM) drives operating in indirect rotor field oriented control (IRFOC) regime. Among all the online efficiency improvement techniques developed for IM drives so far, the loss-model controller (LMC) based approaches are most suitable for industry application due to their fast rate of convergence and superior dynamic response. However, these approaches heavily rely on machine parameters and some of them are computationally very intensive. Thus, this article proposes two different LMCs dedicated for low speed and high speed operations of IRFOC based IM drives. The proposed LMCs are computationally very simple and inherently insensitive to machine parameters. It has been found that an IM drive can be operated very close to its maximum efficiency points both in the low speed and high speed regions by virtue of these LMCs. The procedure for threshold speed selection is also given in this article. As IRFOC itself depends on the rotor time constant, a reactive power based model reference adaptive system is integrated with the proposed method for the rotor time constant compensation. The proposed controllers are rigorously tested in MATLAB/Simulink and experimentally validated with a 5.5 kW IM drive laboratory prototype.