Adaptive Current Control for a Bi-directional Interleaved EV Charger with Disturbance Rejection

This paper presents a double integral sliding mode control (DSMC) and a variable phase-shift algorithm for bi-directional EV (BEV) charger based on front-end bridge-less converter. An interleaved phase-shifted bridgeless converter is widely preferred for AC-DC bi-directional power conversion due to its reduced switching loss and a significant decrease in passive filter components. However, the converter commutation process during phase-reversal in presence of grid distortion often adds complexity to achieve zero voltage switching. Estimation of grid frequency and closer zero-crossing detection (ZCD) at the point of common coupling (PCC) during abnormal grid conditions are the key challenges for the successive operation of bridgeless converter topology. 

This paper describes an adaptive grid-frequency identification technique with noise uncertainty to identify a closer phasereversal occurrence for ZCD. The DSMC, in addition, offers flexibility towards parametric variation with a gain adaptive control. A modification in the phase-shift algorithm of DC-DC power converter is also explained with the inclusion of charging dynamics of battery operation. The DSMC and phase-shift control with improved ZCD, are implemented in Opal-RT platform to verify the charging performance with severe distorted grid conditions. A laboratory prototype for a 3.3kW EV charger is also developed to validate the controller implementation for BEV charging operation.

Keywords— Bi-directional EV charging, power quality, DAB converter, phase-shift operation.