A PI type dead-time compensation method for vector controlled GTO inverters

In the case of GTO inverter, the conventional dead-time compensation methods do not work well, since the terminal voltage of a leg is not constant during the dead-time due to the presence of the snubber circuit. We propose a dead-time compensation method that regulates the voltage error caused by the dead-time. The terminal voltage of each leg is measured by a voltage sensor during the dead-time and its time-average is used for calculating the actual terminal voltage. We obtain an error by subtracting the actual terminal voltage from the command voltage, and generate a compensating term by applying PI controller to the error. At the same time, we also utilize the feedforward compensation method. We verified its performances through computer simulation, as well as experiments. The superior performance of the proposed scheme is evidenced by the reduction in the sixth harmonic component of the motor current