Parallel hybrid

Hybrid vehicle drivetrains transmit power for hybrid vehicles. A hybrid vehicle has multiple forms of motive power.

Hybrids come in many configurations. For example, a hybrid may receive its energy by burning petroleum, but switch between an electric motor and a combustion engine.

Electrical vehicles have a long history combining internal combustion and electrical transmission–as in a diesel-electric powertrain–although they have mostly been used for rail locomotives. A diesel-electric powertrain fails the definition of hybrid because the electrical drive transmission directly replaces the mechanical transmission rather than being a supplementary source of motive power. One of the earliest forms of hybrid land vehicle is the 'trackless' trolleybus of the 1930s, which normally used traction current delivered by wire. The trolleybus was commonly fitted with an internal combustion engine (ICE) either to directly power the bus or to independently generate electricity. This enabled the vehicle to manoeuvre around obstacles and broken overhead transmission wires.

The powertrain includes all of the components used to transform stored potential energy. Powertrains may either use chemical, solar, nuclear or kinetic and make them useful for propulsion. The oldest example is the galley that used sails and oars. A common modern example is the electric bicycle. Hybrid cars combine a battery supplemented by an ICE that can recharge the batteries or power the vehicle.

Among the different types of hybrid vehicles, only the electric/ICE type was commercially available as of 2016. One variety operated in parallel to simultaneously provide power from both motors. Another operated in series with one source exclusively providing the power and the second providing electricity. Either source may provide the primary motive force, with the other augmenting the primary.

Other combinations offer efficiency gains from superior energy management and regeneration that are offset by expense, complexity and the battery limitations. Combustion-electric (CE) hybrids have battery packs with far larger capacity than a combustion-only vehicle. A combustion-electric hybrid has batteries that are light that offer higher energy density that are far more costly. ICEs require only a battery large enough to operate the electrical system and ignite the engine.

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Wikipedia