The fundamental types of hybrid systems are the "series hybrid system", the "parallel hybrid system", and the "series-parallel hybrid system".
Series hybrid system
The series hybrid system generally uses the gas/petrol engine to generate electricity, using the electric motor to drive the wheels.
Parallel hybrid system
The parallel hybrid system uses the electric motor to assist the gas/petrol engine to drive the wheels when the gas/petrol engine's output is weak; for example, when it is operating in the low rpm range.
Series-parallel hybrid system
The series-parallel hybrid system combines the electric motor and gas/petrol engine to drive the wheels, while the electric motor is able to drive the vehicle relying only on electricity generated from the gas/petrol engine or from the battery. This system can control the dual sources of power for optimum energy-efficient operation under any driving conditions.
