Three-Level Flying Capacitor Multilevel Inverter Is Used to Suppress Harmonics at the Output of 3-Phase Inverter Drive and Study of Heat at Various Parts of 3-Phase Induction Motor

摘要

Harmonics are the major cause for degradation of an induction motor; these unwanted harmonics deteriorate the motor performance. In literature, many researchers have studied that application of multilevel inverter suppresses the harmonics. The multilevel inverter has three major types cascaded, diode clamped, and flying capacitor. The output of multilevel inverter is more sinusoidal than of normal inverter. This work shows normal 2-level inverter constructed with six switches and 3-level flying capacitor multilevel inverter constructed with twelve switches experimentally to study the harmonics and total harmonic distortion (THD). Temperature at various parts of the 3-phase induction motor is obtained by placing J-type thermocouples. The motor is run with 9-Hz input frequency for a period of 4-h duration. V/f control method is employed to control speed of the motor. Temperatures obtained for 4-h duration with normal inverter and multilevel inverter are compared. The harmonics and THD is obtained by using a power analyzer for both the inverters, and the results are compared. The load for the motor is kept at 500 g for both inverter topologies, the analysis and reduction of harmonic content are employed to study the 3-phase induction motor temperature, and results are presented experimentally.