Publication Detail

Lowering Cost and Increasing Electrification using the Dual Fuel PHEVs


Presentation Series

Plug-In Hybrid & Electric Vehicle Research Center

Suggested Citation:
Frank, Andrew A. (2013) Lowering Cost and Increasing Electrification using the Dual Fuel PHEVs. Institute of Transportation Studies, University of California, Davis, Presentation Series UCD-ITS-PS-13-02

The most popular hybrid-electric vehicle (HEV), plug-in hybrid-electric vehicle (PHEV) and extended range electric vehicle (EREV) powertrains currently in production all use two electric motors/generators plus a geared transmission set; in some vehicles the engineers add clutches and more gears making for an expensive component. Reducing the cost and improving the powertrains for light- and heavy-duty vehicles with a relatively large battery pack provides the possibility of using high power/torque electric motors to replace the gears and mechanical transmission components. Traditional geared transmissions provide torque multiplication and speed multiplication. In conventional geared transmissions this is called reduction and overdrive. Here we are able to use the battery and electric motors to provide high launch torque and high speed power.


The concepts introduced above can also provide an all-wheel-drive option to provide greater flexibility in advanced electrification of ground transportation systems. The 2 motor EREV or PHEV can easily be configured either way with no loss of functionality. The cost of a PHEV can be further reduced with the use of a standard high volume production manual transmission that has become a commodity. The Automatic drive, 2 Motor Solution from Efficient Drivetrains, Inc. can replace all other powertrain solutions with the possibility of maximum engine downsizing to increase the highway fuel economy and performance. In addition, the "transmission" is dry with no oil and thus requires no maintenance for the life of the vehicle. The result is much higher driveline efficiency. The focus then is returned to the engine and electric motor manufacturers to broaden their elements to increase efficiency and reduces losses and costs further.


Key points:

  • Current HEV and PHEV powertrains can be greatly simplified with little loss in function.
  • HEV systems can get simpler as battery size or all electric range (AER) increases.
  • PHEV allows greater engine downsizing to take advantage of the larger battery pack, which can be flexible to customer use.
  • Additional features can be extracted from the essential components of the HEV powertrain with little added complexity.
  • With constant charging policy, annual displacement of liquid fuel increases with all-electric range and battery size in the PHEV.
  • Vehicle performance and response can increase with battery size.
  • Larger batteries can be used for electrical grid enhancement and renewable energy management using grid-to-vehicle (G2V) and vehicle-to-grid (V2G) chargers, and with an intelligent smart grid; internal combustion engines (ICEs) can support extended exportable power.
  • Light duty PHEVs can use low cost Level 1 charging for normal light duty passenger car use with no range anxiety and near zero tailpipe emissions.
  • Incremental cost of the PHEV must be justified by short payback time.
  • Zero CO2 greenhouse gas pollution can begin NOW if the PHEV or EREV or REEV vehicles are fueled with electricity generated from solar, water and wind energy and with renewable biofuels.


The "end game" for widespread use of PHEVs:

  • Vehicle cost is largely determined by battery size or all-electric range (AER); battery cost reduction continues over time due to volume production and technical advancements..
  • The "road map" is to begin with short AER and smaller fuel savings. Then, Increase fuel displacement and battery size as battery cost/kwhr decreases and fuel prices rise. Eventually with the fleet of cars and trucks in the USA using an average of over 90% electricity and less than 10% liquid biofuel and zero fossil fuels.
  • Batteries of PHEV vehicles can also be charged dynamically (intermittently on the move) as well as statically at lowest possible power to minimize electric infrastructure costs.  But the roadmap starts with "always plugged while parked" recharging.
  • Medium and heavy duty PHEVs will use Level 2 or higher charging infrastructure but cost is minimized by using the lowest possible power needed to supply the energy required by the vehicle mission.
  • Renewable energy (biofuel, solar, wind, hydro) can be used for vehicles today to move toward zero fossil fuel for cars and trucks using PHEVs. But not zero oil or zero coal production!! Because fossil material should be exploited for infinitely recyclable construction and industrial materials for society but not used as fuel thus reducing greenhouse gases and creating plastic materials that can easily be recycled over and over again.