A strategy of dead-time compensation to DFIG

To ensure the double-fed induction generator (DFIG) works safely, dead-time was added to the driving signals. When DFIG works stably, the frequency of rotor current is low, and the effect of dead-time is noteworthy. Distortion of output voltage of the rotor side converter, zero-current clamping phenomenon and asymmetry of PWM pulses would be caused by the addition of dead-time. To eliminate the effect of dead-time, the paper analyzed the influence of it and improved the existing dead-time compensation methods. A compensation strategy was proposed by dividing the space of current vector into six regions in each of which only one phase voltage needed to be compensated. To ensure the symmetry of PWM pulses, the comparison value of PWM generation needed to be modified twice in a switch cycle. The proposed method was tested on the DFIG experiment platform. With the current waveforms before and after dead-time compensation compared, the current with compensation was remarkably better.