Plug-in hybrid electric vehicle
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A plug-in hybrid electric vehicle (PHEV) is a hybrid vehicle with batteries that can be recharged by connecting a plug to an electric power source. It shares the characteristics of both conventional hybrid electric vehicles and battery electric vehicles, having an internal combustion engine and batteries for power. Most PHEVs on the road today are passenger cars, but there are also PHEV versions of commercial passenger vans, utility trucks, school buses, motorcycles, scooters, and military vehicles. PHEVs are sometimes called grid-connected hybrids, gas-optional hybrids, or GO-HEVs.
PHEV Cost Estimation
The cost for electricity to power plug-in hybrids for all-electric operation in California has been estimated at less than one quarter of the cost of gasoline <ref>Edward Taylor and Mike Spector , 2008, GM, Toyota Doubtful on Fuel Cells' Mass Use, Wall Street Journal, Mar 5, 2008, Summary: Executives of General Motors and Toyota announce that they do not see their companies pursuing hydrogen fuel cell technology for future mass market vehicles. They do, however, forsee producing electric vehicles or PHEVs by 2010 with a 300 mile electric only range. </ref>. Compared to conventional vehicles, PHEVs can reduce air pollution and dependence on petroleum, and lessen greenhouse gas emissions that contribute to global warming. Plug-in hybrids use no fossil fuel during their all-electric range if their batteries are charged from renewable energy sources. Other benefits include improved national energy security, fewer fill-ups at the filling station, the convenience of home recharging, opportunities to provide emergency backup power in the home, and vehicle to grid applications <ref>Norihiko Shirouzu, 2008, Race to Make Electric Cars Stalled by Battery Problems, Wall Street Journal, Jan 11, 2008, Summary: General Motors and Toyota announce their pursuit of electric only vehicles, with the current problems being range of vehicle and creating a small enough lithium ion battery without bursting into flames. </ref> .
As of January 2008, plug-in hybrid passenger vehicles are not yet in production. However, Toyota <ref> Teslamotors.com, 2008, The 21st Century Electric Car. (in the process of being updated)  </ref>, General Motors <ref>M. Duvall, 2004, Advanced Batteries for Electric-Drive Vehicles: A Technology and Cost-Effectiveness Assessment for Battery Electric Vehicles, Power Assist Hybrid Electric Vehicles, and Plug-In Hybrid Electric Vehicles. EPRI Project Final Report, May 2004. Summary: Discusses HEVs and PHEVs in terms of battery life and cost for Nickel metal Hydride batteries of different capacity. </ref>, Ford, <ref>C. Reynolds1 and M. Kandlikar, 2007, How hybrid-electric vehicles are different from conventional vehicles: the effect of weight and power on fuel consumption. Environ. Res. Lett. 2 (January–March 2007). Summary: Environmental Research Letters Discusses the effects of weight on fuel consumption of current hybrid vehicles. </ref> Chinese automaker BYD Auto, and California startups Fisker Automotive and Aptera Motors have announced their intention to introduce production PHEV automobiles. The PHEV-60 BYD F6e sedan is expected in the second half of 2008; the luxury Fisker Karma PHEV-50 sports car is slated for late 2009; and the Toyota Prius and GM's PHEV-40 Chevrolet Volt plug-ins are expected in 2010. Conversion kits and services are available to convert production model hybrid vehicles to plug-ins. Most PHEVs on the road in the U.S. are conversions of 2004 or later Toyota Prius models, which have had plug-in charging added and their electric-only range extended.
A plug-in hybrid's all-electric range is designated by PHEV-[miles] or PHEV[kilometers]km in which the number represents the distance the vehicle can travel on battery power alone. For example, a PHEV-20 can travel twenty miles without using its internal combustion engine, or about 32 kilometers, so it may also be designated as a PHEV32km. Another method of characterizing hybrids is based on the ratio of electric power to total power. This number is called the degree of hybridization.
The configuration of PHEV powertrain is mostly identical to hybrid electric vehicle.
Battery Technology for PHEV
High-capacity battery is the major difference between PHEV and regular HEV. There are three major type of battery technologies for the application on PHEV<ref>Tony Markel National Renewable Energy Laboratory (NREL), Plug-in HEV Vehicle Design. Options and Expectations, ZEV Technology Symposium. Sep. 27, 2006. California Air Resources Board. Sacramento, CA. http://www.arb.ca.gov/msprog/zevprog/symposium/presentations/markel.pdf</ref>.
- Nickel-metal hydride (NiMH)
- Co/Ni based Li-Ion
- Iron phosphate based Li-Ion
Modes of Operation
Charge Depleting Mode
This mode allows a fully charged PHEV to operate exclusively on electric power until the batteries state of charge is depleted to a predetermined level, at which time the vehicles ICE or fuel cell can be engaged.
Charge Sustaining Mode
This mode combines the operation of the vehicles two power sources in such a way that the vehicle is operating as efficiently as possible without allowing the battery state of charge to move outside a predetermined narrow band. The battery in the PHEV can thus be though of as an energy accumulator rather than a fuel storage device.
This mode is a type of charge depleted mode normally employed by vehicles which do not have enough electric power to sustain high speeds without the help of the Internal Combustion (IC) portion of the power train.
In this mode a combination of the above modes is utilized.