Abstract:
The research work presents hysteresis current controlled 3-phase PWM converter. The switching control is applied on three-phase bi-directional switches, to attain sinusoidal input current at unity pf. such a rectifier can also operate as unity p.f. converter which is presented in this paper. The rectifier input current controller can be operated with either fixed frequency or variable frequency both with their merits and demerits. The current study includes the current controller and voltage controller implementation with: (i) conventional hysteresis current control (random frequency) (ii) fuzzy controller and PI controller. The various design problems and the performance of the current modulation strategies are investigated & then compared. Rectifier performance parameters, that is, THD and PF are computed.The dc-link voltage is controlled by outer loop fuzzy controller and PI controller. The converter can be used for bi-directional power flow. The bi-directional switches operate at low frequency, crossover zero voltage (at turn-on) and conduct for 1/12th of line voltage cycle. The THD analysis of the controlled input phase current shows significant reduction in the THD as compared to the uncontrolled input phase current in Fuzzy HCC and PI HCC. The dc-link voltage follows the reference value.
