There are several ways in which electric motors and a gas/petrol engine can be combined.

Series Hybrid System

The petrol engine turns the generator. Electric power thus produced is fed to the electric motor that drives the wheels. The power flows to the wheels in series. In other words, power from the petrol engine to the electric motor is connected in series, hence the name Series Hybrid System.

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Parallel Hybrid System

The wheels are driven by the petrol engine and the electric motor. The power source is selected according to the driving conditions. The name of the system comes from the fact that the power sources run in parallel.The petrol engine is the primary power source. The electric motor is used to supplement power during acceleration. However, the electric motor cannot be used to power the car while it is generating electricity.

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Series/Parallel Hybrid System

With the Series Parallel Hybrid System, it is possible to drive the wheels using the dual sources of power (electric motors and/or gas/petrol engine), as well as to generate electricity while running on the electric motors. The system runs the car on power from the electric motors only, or by using both the gas/petrol engine and the electric motors together, depending on the driving conditions. Since the generator is integrated into the system, the battery can be charged while the car is running.

The basic components of the system are the electric motors, the gas/petrol engine, the generator, the power split device and the power control unit (inverter/converter). The power split device transfers part of the power produced by the gas/petrol engine to drive the wheels, and the rest to the generator to either provide electric power for the electric motors or to recharge the battery.

This system takes advantage of the energy-efficient electric motors when the car runs in the low speed range, and calls on the gas/petrol engine when the car runs in the higher speed
range. In other words, the system can control the dual sources of power for optimum energy-efficient operation under any driving conditions.

Toyota has incorporated other cutting edge technologies to improve and develop the powertrain, the generating and control systems. As a result, we are offering many benefits never before possible with a conventional powertrain.

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