DESIGN AND ANALYSIS OF MODIFIED LLC RESONANT CONVERTER FOR ELECTRIC VEHICLE CHARGING INFRASTRUCTURE

Abstract

The design and analysis of Modified LLC Resonant Converter for a single-phase, two stage On-Board charger (OBC) for a light load that may operate in the Grid to Vehicle (G2V) operation mode is presented in this thesis work. The first converter is controlled for this purpose using a Second Order Generalised Integrator (SOGI) control approach, which exhibits a stable steady state as well as excellent dynamic behaviour. The first stage AC-DC converter of an EV (Electric Vehicle) charger plays a very important role in supporting the grid power factor unity. To maintain the grid's power quality PQ at or above the international electrotechnical commission's (IEC)-61000-3-2 standard throughout operations. The efficacy of the design has also been confirmed under a variety of operational scenarios, including the occurrence of Sag and Swell grid voltage. The Modified LLC converter, which is utilized in the second stage of DC-DC conversion, may achieve Zero Voltage Switching (ZVS) for all switches. The modified LLC converter allows for substantially greater Voltage conversion while using fewer switches than a standard LLC converter, which substantially decreases reverse power and turn-off losses. Always using a discontinuous resonant current, the converter runs. To reduce the converter's initial inrush current, clamping diodes were included. To control the switches on the DC-DC converter, a proportional-integral controller is adopted. The battery voltage and charging current are monitored and managed by a PWM controller with a constant battery current. The 3.3kW system ratings are subjected to a thorough simulation investigation. An inductive load has also been linked to the grid to test the responsiveness of the grid.