Investigation on Power Quality Enhancement in Zigzag Configured High Frequency Solid State Transformer Integrated with 12 Pulse Rectifier and Passive Harmonic Mitigation Circuit

In this paper, a hybrid strategy is proposed to improve grid-side current quality suitable for application like electric vehicle rapid charging stations. The approach proposed in this paper uses a direct three-phase multi-pulse rectifier with high-frequency power electronic transformer (PET) configured in zigzag, to avoid bulky line frequency power transformer. To eliminate lower order harmonics and to reduce THD, a 12-pulse diode bridge rectifier circuit is implemented in conjunction with an optimally tapped interphase transformer (IPT) and voltage doubler circuit. The outcome of proposed topology resulted in: The use of massive electrolytic capacitor is eliminated since a weak dc link film capacitor is employed, Higher power density can be achieved due to high switching frequency, 3-phase power electronic transformer provides high frequency galvanic isolation, zigzag configured PET facilitates the avoidance of the usages of zero sequence blocking transformer, simple duty cycle control scheme for the regulation of dc output voltage. MATLAB Simulink is used to analyze and simulate the proposed model. The result shows that this hybrid topology enhances the power quality and meets with the IEEE-519 standard for THD of less than 5 percent.