Basically, there are four main types of electric vehicles:
- Pure electric vehicles, also known as battery electric vehicles (BEV).
- Hybrid vehicles (HEV).
- Plug-in hybrid electric vehicles (PHEV).
- Fuel cell vehicles (FCEV).
Battery electric vehicles: These use batteries to power an electric motor to propel the vehicle. This produces no tailpipe emissions. The batteries are recharged from the electric grid, as well as from regenerative braking.
There are several challenges with this type of EV. Among them: improving battery technology to lower costs, increased energy density and extended durability; possible need for more recharging infrastructure; and extending the mileage range.
Hybrid electric vehicles: These are powered by both an electric motor and an internal combustion engine, independently or jointly (serial or parallel hybrid). A hybrid is designed to capture energy that is normally lost through braking and coasting to recharge the batteries (regenerative braking), which in turn powers the electric motor. There is no need to plug this type of vehicle in.
With a parallel hybrid electric vehicle, both the internal combustion engine and the electric motor generate the power that drives the wheels. Parallel hybrids can use a smaller battery pack and, therefore, rely mainly on regenerative braking to keep it recharged. However, when power demands are low, parallel hybrids also utilize the drive motor as a generator for supplemental recharging, much like an alternator in conventional cars.
A series hybrid electric vehicle is the simplest hybrid configuration. It uses an electric motor to provide added power to the internal combustion engine when it needs it most, for example, in stop-and-go driving and acceleration.
Along with giving performance benefits and reducing
U.S reliance on foreign oil, electric vehicles requires less periodic maintenance, are more reliable and incur lower maintenance costs.
Hybrid electric vehicles may need more maintenance than a typical vehicle since there are two propulsion systems – the regular one and the electric one.
Plug-in hybrid electric vehicles: Like hybrid electric vehicles, plug-in hybrid electric vehicles (PHEVs) are powered by two energy sources: an energy conversion unit, such as an internal combustion engine or fuel cell, and an energy storage device, usually batteries.
The energy conversion unit can be powered by gasoline, diesel, compressed natural gas, hydrogen or other fuels. The batteries can be charged by plugging into a standard 110-volt electrical outlet – a capability conventional battery electric vehicles do not usually have, or may be charged by the energy conversion unit when needed.
Plug-in hybrid electric vehicles have a larger battery pack than conventional hybrid electric vehicles. During typical daily driving, most of a PHEV’s power comes from the stored electricity. For example, a PHEV driver might drive to and from work on all-electric power, plug the vehicle into the grid to charge it at night and be ready for another all-electric commute in the morning.
In addition, plug-in hybrids can be configured to operate serially, or in a blended fashion. In a serial configuration, the vehicle runs on electricity alone at some points, like starting, and uses its other power source alone at other times, for example, when accelerating.
A plug-in hybrid may also be configured for blended operation, having the battery and the conventional engine operate together.
Challenges to PHEVs include the cost and complexity of two powertrains; component availability of batteries, powertrains and power electronics; and higher initial cost. Probably the biggest challenge is the cost and weight of batteries.
Researchers are working to make the plug-in hybrid concept reversible by developing vehicle-to-grid (V2G) technologies. These would allow a two-way connection between the plug-in hybrid electric vehicle and the local utility grid.
This applies, even more to BEVs, but there needs to be development of smart grids first.