Dead-time compensation for VSI based power supply with small filter inductor

For voltage source inverter (VSI) based power supply with small filter inductor, the current ripple of the power switch is large especially under light load conditions. The dead-time effect in this situation is analyzed in this paper. The results show that the dead-time effect is eliminated at most zero-crossing instants of the current. Conventional dead-time compensation methods either average voltage based or pulse based cannot be adopted in this case because the current polarity changes many times within one fundamental period. A closed-loop method for dead-time compensation is proposed for this condition. The proposed method does not need the detection of the current polarity or any extra hardware and is very easy to implement. Experimental results on a DSP controlled three-phase 400 Hz GPU show that the low-order harmonics introduced by the dead-time in the output voltage are almost eliminated completely.