Control of Differential Boost Inverter Based Integrated EV Charger Using Traction Machine Winding Inductances

Abstract

This study introduces control of grid-connected three-phase Differential Boost Inverter in the stationary alpha-beta reference frame for Electric Vehicle (EV) charging operation. The advantage of the approach is that the EV's low-voltage onboard battery bank can be directly contacted with the input-face of the inverter for charging. Only two Proportional Resonant current controllers accomplish this single-stage process. Only two grid side line voltages and two grid line currents are sensed for the control purpose. Also, grid side inductances have been kept very small in the order of low power drive motor inductances. Moreover, the input side current is continuous, which eliminates the need for a high-value electrolytic capacitor at the input side. This improves systems reliability. Compared to a single-phase system, the input parallel topology of three-phase DBI can share more power and be free from second-order low-frequency ripple at the battery current. Also, the DBI can be utilized as a three-phase motor drive for EV motors, even though not pursued in the present work. Reactive current compensation was also brought out. Apart from that, this DBI based charger introduces a very small THD at the grid current waveform. Validation of the concept has been done in the MATLAB Simulink environment.