Speed control of an inverter driven induction motor by Bus-Clamping SVPWM

In this modern age, electrical motors impact innumerable aspects of modern living. Though different kinds of motors are available, it is estimated that Induction motors comprise 85% of all the electric motors in the industrial and domestic applications. With the advancement of Power Electronics, Induction motors have been gaining traction even for variable-speed applications, which was traditionally considered to be the forte of DC motors. The advantages that Induction motors offer due to their high robustness, reliability, low cost and high efficiency (80%) have made them the preferred choice for motor applications Speed control of an Induction motor is possible when it is fed by a PWM-controlled inverter. Among the strategies used to exercise control over the inverter output, SVPWM control delivers more output voltage from the inverter, makes better utilization of DC link voltage, produces lower THD and lower torque ripple than the other popular methods like SPWM method and Hysteresis PWM control method. However, the conventional SVPWM method could still be improved by using a simple Bus-Clamping control logic and maintaining voltage/frequency ratio constant to drive the Induction motor as presented in this work. The impact of this method on the harmonic content of the inverter output voltage is also studied.