Significant reductions in emissions and improved fuel economy have led to a rapid increase in the popularity of hybrid technology in both vehicles and equipment. Advances in power conversion technology, as well as battery design and efficiency, have enabled the expansion of the technology into consumer markets with hybrid vehicles now available at a price point comparable to conventional vehicles.
A popular form of hybrid technology combines an Internal Combustion Engine (ICE) with an electric motor or motors. The ICE is typically powered by gasoline or diesel fuel and the electric motors are usually an induction type or a Permanent Magnet AC (PMAC) design.
Hybrid vehicles can be most simply defined as those which use more than one source of power. Hybrid systems can be further defined by architecture: parallel or series, which indicates how the motors supply power to the vehicle’s wheels.
Parallel hybrid systems - provide a dual power supply that is physically connected to the vehicle’s driving wheels. Either the ICE or the electric motor – or both – can power the vehicle’s wheels.
Series hybrid systems - use two power sources linked together, with only one source directly connected to the vehicle’s transmission. A small ICE is used to power a generator that converts the energy to provide electric power to the vehicle’s wheels and auxiliary devices as well as to a battery system and/or capacitor(s).
When compared to the parallel hybrid design, series hybrid systems achieve better fuel efficiency and emission reductions. Parallel hybrid vehicles tend to be mechanically complex, requiring a larger combustion engine, a transmission, and a mechanism to couple both motors to the drive wheels.
Series hybrid vehicles have no connection between the ICE and the vehicle drive train, relying on stored power to provide for acceleration demands. This allows the ICE to run at optimal speeds resulting in smaller, more efficient engines. Since electric motors drive the wheels, energy saving is also achieved through regenerative braking systems that use the vehicle’s momentum to allow the traction motor to act as a generator, providing braking torque to the wheels and back to the batteries. Parker’s Electric and Hybrid Drivetrain Solutions are outlined in this brochure.
The discussion on series hybrid vehicle technology will be continued in two subsequent posts titled: Series Hybrid Vehicle Electrical Systems and Advantageous Series Hybrid Technology Applications.
For technical details, please reference this white paper: Basic Elements of the Series Hybrid Vehicle.
Product and solution information is also available on the Parker Hybrid and Electric Vehicle website.