Open loop control of induction motor fed by three-phase inverter based on SPWM and SVPWM techniques.

This paper presents a comparative study between sinusoidal pulse width modulation SPWM and space vector pulse width modulation SVPWM techniques to control a three-phase inverter which in turn used to drive a three-phase induction motor. The motor open loop control, based on the efficient voltage to frequency constant ratio (V/F) strategy, is employed in this work. A Simulink MATLAB models for both techniques were built and experimented for different three phase induction motor speeds and the motor is subjected to external load torque for actual working conditions. Theoretical analysis states that the motor torque decrease with decreasing input voltage and decreases with increasing operating frequency. Adopting SPWM and SVPWM help to control both input voltage and frequency in a way to cancel these drawbacks. Results show that the torque of the motor is kept constant (as required) when the speed is changed in both SPWM and SVPWM techniques. The THD for all the speeds for SPWM is shown to be with the range of the acceptable in IEEE standards compared with a lower value of THD for SVPWM. The frequency of switching power MOSFET's decreases when the reference motor speed decreases which results in decreasing the THD for SPWM and SVPWM techniques. The SVPWM technique utilizes the DC supply better than SPWM and the THD for SVPWM is found less than THD for SPWM for all cases. [ABSTRACT FROM AUTHOR]