M.ICROCONTROLLER BASED, PWM INVERTER FED INDUCTION MOTOR DRIVE

Abstract

This dissertation concerns with the variable-frequency operation of a three phase squirrel-cage Induction Motor using PWM VSI employing MOSFETs. The space vector technique is used for PWM pattern- generation -having smooth voltage - control with variable frequency. PWM. inverter. is operated • in sinusoidal mode. The foreground/background approach - is used for the calculation of PWM pattern table. The program . is written in Assembly language for 8031 microcontroller which is used as CPU to generate firing commands. The PWM signals generated by microcontroller are interfaced to the MOSFET based PWM inverter through an optical isolation circuit. the PWM . inverter also incorporates an electronic overcurrent sensing scheme to protect the power devices against over load and shoot through. The - inverter syst. em-k developed is tested on three phase Induction motor on No-load and at load. Waveforms for machine terminal voltage and Line current at different frequencies are recorded. Finally, the results are presented.