DENSO Develops Vehicle-to-Home System for Electric Vehicles

DENSO Corporation has developed a vehicle-to-home (V2H) power supply system for electric vehicles (EV), which is designed to work in coordination with DENSO' s home energy management system (HEMS).

"DENSO and Toyota is working together to develop a V2H power supply system that uses alternating current, and has been conducting demonstration tests using plug-in hybrid vehicles (PHV) to ensure the system can efficiently use energy," said Hikaru Sugi, senior executive director of DENSO' s Engineering Research and Development Center and President and CEO of DENSO International America, Inc. "With our newly developed system, we will now perform demonstration tests on a V2H power supply system that can be also used for EV."

The V2H system can quickly charge an EV with direct current from the HEMS storage battery, and can supply the electricity in the EV back to the household. In addition, the system can efficiently distribute electricity, including power generated by residential photovoltaic systems (solar panels), to the EV and to the home through the coordination of the HEMS.

The two main features of the new system are as follows:

1. Quick recharging function using a HEMS storage battery

Because an EV is battery-powered, the battery needs to be quickly charged for the car to be practical and functional, particularly when the battery level is low. However, a quick charger uses a substantial amount of power, resulting in an increase in the consumer' s electricity contract/bill and it is difficult to install for household use.

DENSO' s new system can quickly supply the electricity that is stored in the HEMS storage battery to the EV when charging at home, which doesn't require a dedicated charging device. Within just 15 minutes of charge using the DENSO system, the EV can travel up to about 20 km (12.43 miles)

2. Eco-V2H function

The HEMS can estimate the daily EV travel distance and household power consumption to best manage the charging and discharging of the electricity of EV and HEMS battery unit. Also, to achieve local production of energy for local consumer consumption, the energy surplus produced by the photovoltaic system can be stored in the EV or the HEMS storage battery as opposed to being sold to the local electric power company(1). During the electricity peak time, surplus electricity stored in the HEMS storage battery is supplied back to the house to enable electricity peak shift. These functions require technology to combine electricity supplied back to the home from the EV and commercial power(2)(3). Moreover, in emergencies such as natural disasters, electricity stored in the EV can be used at home in the same way as the PHV.

The new system was developed in line with the trend toward the standardization of V2H power supply systems. In this demonstration project, DENSO plans to use EV developed by Toyota Motor Corporation and Mitsubishi Motors Corporation.

Looking ahead at the next generation of energy and social systems, in 2013 DENSO plans to start demonstration tests in Toyota City to find a way to optimally use home energy using an EV or PHV as the key element, and to develop and commercialize an efficient energy management system to help realize a low-carbon society.

(1) It is mandatory for electric power companies in Japan to buy renewable energy such as solar power, generated by households

(2) Using a combination of electricity supplied back to the home from the EV battery and commercial electricity means grid connection, which feeds the output from dispersed power sources, such as photovoltaic systems and storage batteries, into the commercial power grid. To maintain the quality of electricity, grid connection requires technology to synchronize the frequencies and phases between different types of electricity.

(3) Commercial power: Electricity, also known as grid power, purchased by households from electric power companies.

(4) EDMS: Energy Data Management System: Collect and analyze data on energy use to support the achievement of effective energy use for the entire society.

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