Three-phase infinite level inverter fed induction motor drive

Abstract

Traditional voltage source inverter (VSI) used to drive a three phase induction motor (IM) is a two level inverter. Various control techniques are employed to improve the DC-link utilization and to reduce the DC-link voltage. Lower DC-link voltage reduces the voltage stress across active switches and passive elements, thereby increasing the inverter reliability. Multi-level inverters are used in medium and high voltage IM drives to reduce voltage stress and harmonic content but the tradeoff is in the complexity of control circuit and increased number of active & passive elements. A new type of VSI drive called three-phase infinite level inverter (ILI) based IM drive is proposed to mitigate the above problems to a great extent. This modified VSI topology fed to IM has many number of voltage levels with same number of components. This drive requires only 0.576 times the DC-link voltage compared to space vector PWM inverter fed IM drive. No dead time requirement, low voltage stress and high DC-link utilization are the various advantage of this drive. Increasing number of voltage levels demands no extra devices in the circuit. Simulation using MATLAB/Simulink is presented to verify the above results. Experimental waveform obtained with the generation of voltage waveforms from the infinite level inverter and fan type load is shown.