A Unified Control of Grid-Interactive Off-Board EV Battery Charger with Improved Power Quality

In this project, a self-tuning filter (STF) and sliding mode control (SMC) based control algorithm for a grid interactive off-board electric vehicle (EV) battery charger to power the EV batteries and simultaneously improve the grid power quality. In grid-connected operation (GCO), the charger uses the STF based control strategy to estimate the fundamental load current and synchronizing voltage templates to generate a pure sinusoidal reference current. Compared to phase-locked-loop (PLL) and second-order generalized integrator (SOGI), the STF based technique precisely estimates the synchronizing voltage templates during non-ideal grid voltage conditions. Therefore in GCO, the charger reference current ensures unit power factor in grid-to-vehicle/vehicle-to-grid (G2V/V2G) operation mode and harmonic free grid current in charger-for-grid (C4G) operation mode. Furthermore, the charger operates in vehicle-to-load (V2L) operation mode during grid outages to maintain an uninterrupted supply to the residential load. The control algorithm also includes a grid synchronization technique to achieve a smooth transition between GCO and V2L. Furthermore, an SMC-based DC-link voltage controller (SMC-DLVC) is proposed to reduce DC-link voltage overshoot with finite-time convergence during external disturbances in all operation modes. The simulation results can be evaluated by using Matlab/Simulink Software.

Keywords: Charger-for-grid (C4G), EV battery charger, G2V, Power quality (PQ), Sliding mode control, V2G.