Hybrid Car Review

There are two types of hybrid engines. These two engines are differentiated by how the electric and fueled halves of the powertrain connect.

A parallel system is the most common design seen today. It connects the electrical and internal combustion systems to the mechanical transmission.

Most designs combine a large electrical generator and a motor into one unit, often situated between the internal combustion engine and the transmission, in the location of the flywheel, replacing both the conventional starter motor and the generator or alternator.

In some cases, the electrical generator only provides a boost to the primary power source, the gas engine. In other cases, the electrical generator can be considered a co-primary power source. The electric side of the engine will power the engine up to a certain speed, at which point the gas engine will turn on and produce the primary power. This allows the gas engine to provide power only when it is most efficient to do so.

A large battery pack is required in a parallel engine. The battery will be charged both through regenerative braking and by the gas engine, when needed.

Accessories normally powered by the engine, such as power steering and the air conditioning are powered by the electric motors. This allows them to keep running when the gas engine is off. This offers the possibility of further efficiency gains, by modulating the electrical power delivered to these systems, rather than having them run directly from the engine at a speed which depends on engine speed.

Read about Series Engines.