Bidirectional EV charger with ancillary power quality capabilities

Abstract

This paper presents a bidirectional electric vehicle (EV) charger with ancillary power quality (PQ) capabilities in grid-to-vehicle (G2V), vehicle-to-grid (V2G) and vehicle-to-home (V2H) applications. The proposed configuration consists of a five-level (5L) neutral point clamped (NPC) converter in cascaded with a dual-active half bridge (DAHB) DC-DC converter. The proposed cascaded control strategy used for regulating the common DC bus voltage as well as for compensating the grid current harmonics and the reactive power through the 5L-converter is based on a performant proportional-resonant (PR) compensator. By applying the single-phase-shift (SPS) technique to the DAHB converter, the battery power flow is accurately regulated. A detailed study with exhaustive tests and simulation results obtained in MATLAB-SimPowerSystems for a full-scale power system based on a Nissan Leaf´s battery validate the fairly good performance of the proposed configuration and control strategies. The main achievements of this work are: 1) the system’s stability is maintained even during fairly abrupt changing conditions, 2) in steady state of the G2V/V2G operation modes, the total harmonic distortion (THD) of the grid current remains below 3% while the power factor (PF) is kept at unity, 3) the reactive power demanded from the grid is zero in spite of feeding a highly nonlinear load, and 4) when a power outage occurs, the transition to the V2H mode is seamless and the home load is uninterruptedly supplied with a very low-distortion output voltage from the 5L-converter.