Certain investigations on harmonic mitigation in v f control of three phase induction motor drive for a wheat flour mill

Abstract

Consumption of Wheat in India has sharply increased in the last two decades. An average consumption of 105000 MT in a year requires setting up more flour mills to meet the needs. In addition to the cost of raw materials and labour, the flour mills have to pay huge amounts towards commercial electricity charges making it challenging for many such industries. Since profit margins are generally low in the wheat processing industry, efficient management of energy consumption has become a vital parameter. In this context, employing an energy saving system at the flour mill gains importance. f such a system could be successfully integrated with the flour mill, consumption of energy could also be reduced to a greater extent. Out of the total energy consumed by the flour mill, the cleaning system alone consumes a significant amount of energy. Hence, by employing variable frequency drives (VFD) for fans in the cleaning section and purifier, large amounts of energy can be saved, which in turn would reduce the electricity charges. If the V/f drive is used in a fan control application, up to 50% of energy could be saved. Therefore, VFDs are widely used in flour mills for energy savings. V/f ratio is maintained as a constant to maintain the air-gap flux in V/f drives. The rectifier unit of a V/f drive produces oscillations in the AC line when it charges a capacitor unit in the DC bus. Current is consumed from the AC line when the AC-DC converted voltage surpasses the level of voltage to which the capacitor is charged. Extreme harmonic distortion has many unfavorable impacts. Voltage distortion formed by the VFD results in quotflattoppingquot of the power system voltage waveforms, which in turn causes the sensitive electronic components to malfunction newline