An Implementation of Induction Motor Drive with Half Wave Symmetrical SVM

摘要

In this study, the half wave symmetrical Space Vector Pulse Width Modulation (SVM) is employed in a v/f controlled three phase induction motor drive system with the intention of reducing harmonic components of the three phase currents feeding to the induction motor windings without using any artificial intelligence algorithm. The most important part of induction motor drives is the inverter. Inverters are used to convert direct current to alternative current and to modulate amplitude and frequency of the converted alternative current. For control of inverters, various Pulse Width Modulation (PWM) methods have been proposed so far. Among them, SVM method is the most frequently preferred method since it has certain advantages over the other PWM methods. These are primarily efficient DC-bus voltage utilization, high harmonic performance and low switching losses. However, conventional SVM does not have half wave symmetry and hence even order harmonics appear in the output voltages of the inverter. The half wave symmetrical SVM can be achieved by utilizing a specific switching sequence and hence provides better harmonic performance while preserving all the other advantages of the conventional SVM. In this study, the SVM with such switching pattern is applied to an induction motor drive system in order to minimize harmonic components, especially low order harmonics, of the three phase currents feeding the motor windings.