DSP Based Real Time Output Waveform Synthesis for Three Phase PWM Inverter

A new digital control technique is proposed to synthesize arbitrary three phase PWM inverter output. Sensing two line-to-line voltages, the required pulse patterns for deadbeat response are computed in real time manner, based on the predicted voltage by an observer at 18kHz sampling frequency. When used for the uninterruptible power supply, this closed loop voltage control inherently results in a very low THD and a very quick transient response with the less filter capacity. Also with repetitive compensator, the proposed scheme has advantages in improving the output waveform for non-linear load. This paper describes modeling technique, theoretical analysis, simulations and experimental results.