Keywords: harmonic distortion, overmodulation, pulse width modulation, PWM, pulse width modulated inverters, synchronisation, space vectors, voltage source inverters, VSI
Improved space vector PWM algorithm for three–level voltage source inverter in overmodulation region
In high power high performance AC drive industrial applications, multilevel inverters have established their importance, as they can synthesise output waveform with improved harmonic spectrum. In this paper, an improved synchronisation and symmetrical SVPWM algorithm is proposed for three–level inverter in overmodulation region for better utilisation of DC bus and to reduce harmonic distortion. The performance analysis of the proposed algorithm is compared with SHEPWM and STPWM for three–level voltage source inverter in terms of THD of line voltage and motor current along with fundamental component of the line voltage. It is shown that the proposed algorithm gives improved results compared to SHEPWM and STPWM algorithms. The algorithm is also verified experimentally on a constant v/f drive fed from IGBT–based voltage source inverter using Motorola power PC (MPC8240) based embedded controller.