Dead-time compensation in the zero-crossing current region

The compensation of the effects of the dead-time based on the modification of the pulse-width of the command signals requires the knowledge of the polarity of the current flowing through the power switch. This polarity defines if the pulse-width must be widened or shortened. In the zero-crossing current region it is difficult to determine the current polarity and thus the compensation may be incorrect and consequently the output inverter voltage can be distorted. This article discusses such polarity based compensation technique and proposes a solution to minimize the inverter voltage distortion in the zero-crossing current region. In the proposed solution, the polarity of the current together with its instantaneous value are employed to correct the pulse-width. The proposed solution has been tested experimentally and the results obtained were considered satisfactory when compared to the standard technique where the compensating term is kept fix no matter what are the polarity and the magnitude of the current flowing through the power switch.