Hyundai Mobis has developed the Bi-directional On Board Charger (OBC) for electric vehicles, which is key to the implementation of V2G (Vehicle To Grid).
V2G refers to using the idle power while plug-in environment-friendly cars, such as EV and PHEV, connected to the grid, are parked. The electric vehicle is charged while connected to the grid, and the electricity remaining after the day’s operation is transmitted (and/or discharged) back to the grid. The electric vehicle effectively becomes a moving Energy Storage System (ESS).
The electric power supplied by vehicles can be used as emergency power in households and cities. Four electric vehicles can supply energy that can be used by 20 households in a day. If more vehicles are available, the surplus power can be secured and large-scale blackouts may be prevented. Damages to industries due to blackouts are estimated to be KRW 650 billion ($570 million) a year in Korea.
The industry estimates that if V2G is applied to 100,000 vehicles, 500MW power, equivalent to the power generation of a thermoelectric power plant, will be secured. Experts say that “In general, automobiles are being used less than 20% of the time, and they are parked in the remaining time,” and it will be very effective. Currently, pilot V2G projects are being actively carried out in Japan, Denmark, the US and China.
The bi-directional OBC uses an AC↔DC converter and step-up / step-down converter to convert direct current and alternating current in both directions and to synchronize voltage and power frequency with the power grid.
The actual vehicle verification begins with a dedicated charging station diagnosing the power state of the vehicle, such as battery efficiency and capacity. The optimal V2G schedule is then created according to the hypothetical scenarios in which the power supply, cost, and load are analyzed. The vehicle receives the data signal and repeats charging and discharging according to a predetermined schedule.
The Hyundai Mobis bi-directional OBC is same size as the conventional charger of the Ioniq (which Hyundai Mobis supplies to Hyundai), but with increased the energy efficiency. Both the charge and discharge outputs have achieved 6.6kW—the same level of technology as Japan.
Hyundai Mobis has participated in the ‘V2G test bed project,’ which Korea Electronic Power Corporation (KEPCO) has been conducting since 2015, and was responsible for developing the bi-directional OBC. Hyundai Mobis is the first in Korea to install the bi-directional OBC in environment-friendly vehicles, verify safety performance, and develop it to the commercial level in a test bed project.
In future smart cities, many electric vehicles will be charged at the same time. To reduce the resulting power load, V2G is essential. The successful development of the bi-directional OBC enabled Hyundai Mobis to respond more proactively to the global V2X (Vehicle To Everything, including V2G) market, which is expected to grow to KRW30 trillion ($26.7 billion) by 2025.