Nick Hood, UK Sales Manager at Autoelectro, outlines how the design of alternator and starter motors has kept pace with the evolution of hybrid technology.
Stop-start systems and regenerative braking
Most stop-start systems use a conventional alternator and heavy-duty starter motor, but one of the more technologically advanced or altered systems in the micro-hybrid designation is the Valeo-developed iStARS (Starter Alternator Reversible System) – Autoelectro part numbers AEG9005 and AEG9009 are popular examples of these. The vehicles using this technology have an alternator that runs a conventional 12V system. However, in this case, the alternator also works as a starter motor, by reversing the alternator and starting the engine using the auxiliary drive belt. This system is ECU controlled, and once the vehicle is started, the iStARS switches back to being an ECU-controlled alternator, charging at a variable voltage as directed by the ECU in response to the demands of the vehicle.
Vehicles with this technology often have a conventional starter motor for cold starting, but the reversible alternator means that there is no pinion to re-engage, and results in a smoother and quicker restart process.
The company also offers an alternator (AEK4006) that can be fitted on Mazdas with regenerative braking; this is an ECU-controlled alternator which can charge at up to 25V under braking. The overcharge is stored in a capacitor and redeployed on demand, normally under acceleration, which means the alternator does not charge under acceleration, thus reducing load on the engine and increasing performance and fuel consumption. Overall, it is a more developed and advanced ‘Smart Charge’ system that is used by many manufacturers already, where an ECU controls the alternator and its operating protocols.
Catering to full hybrid demand
Although the previously mentioned components are good examples of how the function of an alternator is changing, they are by no means the full picture. Autoelectro also has a full hybrid-supporting alternator available from stock that can be fitted to the latest Peugeot 508 and 5008 hybrids.
To clarify, a ‘full’ hybrid is a vehicle that can be driven on an electric motor as well as on its combustion engine. For these references, Autoelectro has part number AEG9008, which is an iStARS type of combined part (reversible and capable of starting the vehicle). The difference is that this version has an 8kW 415V output that supports the charging of hybrid batteries. The alternator functions at both 415V for the hybrid powertrain and 12V for the vehicle electrics.
The 48V future
Many within the industry will be aware of a move to 48V electrical systems. In fact, within the next five years, it is estimated that one-fifth of all cars sold will operate on this system.
The idea behind the 48V system is to power vehicle systems that were once mechanically powered, such as power steering, pumps, fans, etc. Operating these electronically reduces the amount of drag on the internal combustion engine and gives a vehicle’s central processor greater control over performance and efficiency, thereby maximising the overall operation.
At the heart of this 48V system is regenerative charging; a process that has the ability to harness the kinetic energy produced during braking. The energy is often recovered via an Integrated Starter Generator (ISG) mounted between the engine and transmission that converts the kinetic energy into electricity and supplies a compact 48V lithium-ion battery pack. The ISG also powers the conventional 12V system via a voltage converter. This ISG can also act as a starter motor, with the ability to spin the engine very fast and start the engine quicker than a standard starter motor, giving a smooth stop-start operation. The electric motor can also be used to boost the torque and horsepower to a vehicle’s engine when needed.
However, for the aftermarket, the 48V future has not arrived quite yet, although when it does Autoelectro is well placed to support garages through the change.