| A Digital Signal Processor (DSP) based voltage fed Insulated Gate Bipolar Transistor (IGBT) inverter that drives a three-phase induction motor is presented in this thesis. In order to reduce harmonics in the output voltage waveforms as well as switching losses, the proposed Pulse Width Modulation (PWM) algorithm operates in a hybrid mode that utilizes a uniform sampling scheme in the low-frequency region, whereas a harmonic elimination method is used in the high-frequency region. Several frequency ratios are applied in the uniform sampling region and the dominant harmonic frequencies are kept above 400 Hz. In the harmonic elimination region, four low-order harmonics (5th, 7th, 11th, and 13th) are eliminated so that the 17th is the dominant harmonic order. A special technique is also applied for a safe transition between the two PWM modes.;The output voltage and current waveforms as well as the harmonic spectrums are measured by a FLUKE 41 power harmonics analyzer and the results show significant reduction in low-order harmonics. |
