Conventional Drive System
In conventional drive systems, the mechanical energy developed by the internal combustion engine (ICE) drives the wheels through a transmission. Some of the energy delivered to the drive wheels is used for acceleration. When brakes are applied, the kinetic energy of the vehicle is converted mostly to heat in the brake pads, resulting in the wear and tear of the brakes and wasteful energy consumption.
Depending on the application, more than half of the energy delivered to the drive wheels is dissipated in the brake pads.
Hybrid Drive System
In hybrid drive systems, an electric motor is used to provide some (parallel hybrid) or all (series hybrid) of the power to the drive wheels. This lowers energy consumption and increases the efficiency of the electric power supplied by the electric motor, compared to the mechanical energy of a conventional ICE.
Hybrid drive systems can also recapture the kinetic energy converted to heat during braking, known as regenerative braking. The recaptured energy can be stored or used for acceleration. This energy “recycling” increases fuel efficiency and reduces wasteful energy consumption, also leading to lower emissions.
Series vs. Parallel
In a parallel system, the ICE is still connected to the drive wheels through a transmission like in a conventional drive system. In a series system, there is no mechanical connection between the ICE and the drive wheels, the engine is completely decoupled and used only to generate electric power. The electric motor is directly connected to the rear wheels without the use of a transmission.
In this way, a series system is better suited to operate in an all-electric mode and when a vehicle is operating in an all-electric mode, the ICE is not operating at all. During this period, the vehicle will be a zero-emissions vehicle (ZEV). It is not practical to use a parallel system for ZEV operation over an extended period of time.
ISE’s drive system operates on a series hybrid architecture,
paving the way to clean zero-emission technology and
driving the road ahead to more sustainable hybrid drive applications.
