Space Vector PWM as a Modified Form of Sine-Triangle PWM for Simple Analog or Digital Implementation

Abstract

Conventional space vector PWM (CSVPWM) has the advantages of yielding up to 15% higher fundamental line-side voltage for a given DC bus voltage and also less harmonic distortion in line currents over sine-triangle PWM (SPWM). However, no analog implementation of CSVPWM is possible in its traditional form. Digital implementation of CSVPWM is also more complex than that of SPWM. This paper analyses the two techniques. The analysis establishes that CSVPWM can be viewed as a modified form of SPWM, and leads to a simple method to implement CSVPWM. The simplified method does not require evaluation of trigonometric functions, look-up tables, sector identification etc. An existing line of products employing SPWM can easily be upgraded to exploit the benefits of CSVPWM. The work serves to unify the understanding of triangle-comparison based PWM and space vector based PWM techniques. The work is of tutorial value to students and engineers.

Indexing terms:

• Inverters
• Motor drives
• Pulsewidth modulation
• Sine-triangle PWM
• Space vector PWM