Bidirectional Bus Transfer Method for Induction Motors Between Inverter and Grid By Correcting Control References Using Discrete Fourier Transformation
Subject Areas : electrical and computer engineering
Alireza Lahooti Eshkevari
1
,
Ali Keshavarzian
2
,
Iman Abdoli
3
,
Mohammad Farzi
4
,
Seyed Mohammadreza Zeinalhosseini
5
1 -
2 - Iranian Research Institute for Electrical Engineering
3 - Iranian Research Institute for Electrical Engineering
4 - Iranian Research Institute for Electrical Engineering
5 - Iranian Research Institute for Electrical Engineering
Keywords: Motor bus-transfer, variable speed drive, induction motor, synchronization,
Abstract :
This paper presents a new method for bidirectional bus-transfer of an induction motor, between the inverter and the grid, based on discrete Fourier transform. In this method, without affecting the motor control strategy and only by correcting the amplitude and frequency references (or by correcting the flux and torque references), the phase, amplitude, and frequency of the output waveform of the inverter are synchronized with the grid. It enables changing the source of a motor without interruption. Due to the extraction of the fundamental component of the waveforms of both sources, this method is robust against to noises, DC pollution and harmonics. Due to eliminating proportional-integral controllers in determining each of these parameters, there is no need to adjust their coefficients . Also, due to the high accuracy of synchronization, instantaneous parallelization of voltage sources is realized without the need for additional devices. The maximum circulating current caused by parallelization in the worst cases is limited to less than 1.5 times the rated current of the motor. This article, while presenting the proposed method in detail and comparing it with some previous methods, uses laboratory results to evaluate its achievements. Experimental results confirm the above achievements.
