Space Vector Pulse width Modulation and Determination of PWM Time Intervals For Inverter Timer In A.C. Drives

Abstract

Sinusoidal PWM has been a very popular technique used in AC motor control. This relatively unsophisticated method employs a triangular carrier wave modulated by a sine wave and the points of intersection determine the switching points of the power devices in the inverter. However, this method is unable to make full use of the inverter’s supply voltage and the asymmetrical nature of the PWM switching characteristics produces relatively high harmonic distortion in the supply. This paper highlights the core concepts of SVPWM. It describes the space vector modulation theory which can be utilized for Space Vector PWM (SVPWM) - a more sophisticated technique for generating a fundamental sine wave that provides a higher voltage to the motor and lower total harmonic distortion. Mathematical formulae are derived for PWM time intervals using space vector modulation theory. SVPWM is also compatible for use in vector control (Field orientation) of AC motors.