**6. Conclusions**

This paper proposed a model predictive control composed of model predictive direct power control and a model predictive direct current control schemes for three-phase twostage off-board bidirectional EV chargers. The MPDPC method was designed to track the grid active/reactive power references for the AC/DC converter. The MPDCC scheme was applied in a second-stage DC/DC converter for constant current charging. The proposed system controller receives the discharging and charging currents from the EV charging stations. With the proposed method, the bidirectional charger can operate in G2V or V2G with/without the capacitive/inductive V4G modes. The EV battery can not only exchange active power with the grid, but can also function as a static var compensator to improve the power quality based on the grid requirements. It can be seen from the simulation and experimental results that the designed MPC scheme has a fast dynamic response and good steady-state performance. The demands from both the grid and the EV batteries can be met effectively. However, there are some gaps between the laboratory and real-life off-board EV chargers, including the power level, charging conditions, and battery types. (a) In the real-life EV chargers, the power level is much higher than in the laboratory ones. In the US Society of Automotive Engineers (SAE) J1772 standard, DC Level 1 and DC Level 2 are the two levels of fast DC charging, with a rated power equal to 80 and 400 kW, respectively. (b) Only the initial constant current charging operation is considered in this

 Battery paper. Generally, the constant voltage charging mode in the final process is required in most real cases. (3) In the current EV market, due to their long lifetime and high energy density, lithium batteries are used in the real vehicles, rather than sealed lead-acid batteries. (4) An isolated DC/DC converter is used in real-life chargers to protect EV batteries and the grid. To narrow the gap between the scaled-down laboratory setup and the real-life deployment, a high-power-level topology with an isolated DC/DC converter interfaced with lithium batteries will be considered in future work.

**Author Contributions:** All authors contributed to the research in the paper. Conceptualization, T.H.; formal analysis, T.H. and D.D.-C.L.; methodology, M.W. and T.H.; project administration, M.W.; supervision, D.D.-C.L.; validation, T.H. and Q.L.; writing-original draft, T.H.; writing-review and editing, T.L. and Q.Y.; all the authors have read and approved the final manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported in part by Fundamental Research Funds for the Major Projects: KEJB0220001536.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Not applicable.

**Conflicts of Interest:** The authors declare no conflict of interest.
