Research on the influence of reducing dead-time on the output of hybrid active power filter

In practical application of active power filter, to avoid damage to power switching devices, a few seconds of dead-time must be inserted in the switching signals to prevent a short circuit. This will cause the deviation of the output voltage waveform, such as the decrease of the fundamental wave, increase of the harmonic amplitudes. The dead-time effects will be more serious as the modulating frequency rises up. The static and dynamic performance of the system will go down, which will affect the effective function of the high speed on-off devices, and increase the difficulty of depressing the low-order harmonics. This paper analyses the working principles of dead-time effect, it may practically be seen as a cyclic disturbance signal. By adopting current feedback compensation method, the PWM pulse widened or compressed by dead-time period can be compressed or widened, thus effectively compensating dead-time effect. Finally the application results indicate that the active power filter system can provide the required signals perform filtering and compensation.