Types of Hybrid Electric Vehicles (EVs)

The ultimate goal is the introduction and transition to zero-emission vehicles, like the BEVs and FCEVs outlined in the previous step. Hybrid vehicles have emerged as a solution to current constraints such as limited vehicle range, inadequate recharging infrastructure and challenges associated with heavy duty vehicles. These vehicles integrate an electric motor with an internal combustion engine.

The graphic below illustrates different vehicle classification categories, including vehicle types and the corresponding types of motors they operate with. This article focuses on hybrid vehicles. The mild hybrid, for example, does not allow full electric driving. In this case, the electric powertrain is only used to support the internal combustion engine.

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Vehicle classification PEM Motion (2022)

Other forms of electrification are presented individually below, and applications for different vehicle segments are outlined.

– PHEVs

A plug-in hybrid electric vehicle (PHEV) is a motor vehicle with a hybrid powertrain that combines an internal combustion engine with an electric motor. Due to a relatively small battery capacity a PHEV can be driven in electric-only mode for short distances (up to 50 km). The battery can be charged either from the internal combustion engine or by an external power supply.

The plug-in hybrid concept allows the user to make a ‘smooth’ transition from conventional to electric driving. Regular charging can reduce the environmental footprint and costs, but is not necessarily required to use the vehicle. This helps to alleviate the range anxiety that many users have with electric vehicles. However, if PHEVs are primarily powered by an internal combustion engine, the increased weight and production costs of the dual powertrain will have a negative impact on the environmental balance.

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Plug-in hybrid electric vehicle components. Power Sonic (2022)

PHEVs concept is mainly used in smaller vehicle segment such as cars, since the smaller vehicle classes can be driven without the range-extending ICE, and larger vehicles have long distances where the benefit of plug-in charging for 15-60 km is negligible.

When the battery is discharged, the car automatically switches to ICE and can travel several hundred kilometres on one tank of fuel. The battery can be recharged by an external charger or by the ICE, which can dramatically reduce fuel consumption and emissions, especially on short journeys.

– HEVs

HEVs, sometimes called ‘self-charging hybrids’, use both an internal combustion engine and an electric motor that relies on a relatively small battery pack compared to a BEV/PHEV. The main difference between a PHEV and an HEV is that the HEV cannot be charged from an external power source. Instead, the on-board battery pack is charged by the engine and regenerative braking. The extra power generated by the electric motor allows the vehicle to have a smaller engine.

The battery pack acts as an auxiliary power source for the vehicle, helping to reduce idling when stationary, resulting in better fuel economy and lower emissions than a vehicle with a conventional engine. The HEV concept is increasingly being seen in buses, as these vehicles have a high potential for fuel savings in urban areas. Buses typically drive in a stop-and-go cycle, and because of their large mass, a lot of energy can be recovered during braking, saving fuel.

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Hybrid electric vehicle components. Power Sonic (2022)

There are different types of HEVs, which include:

• Mild Hybrid Electric Vehicles (MHEVs) – also known as ‘micro hybrids’, ‘power assist hybrids’ and ‘battery assisted hybrid electric vehicles’ (BAHVs) – use the battery pack and electric motor to help power the vehicle and allow the engine to shut off when the car is stationary. MHEVs cannot drive the vehicle on electricity alone and are less fuel efficient than a full hybrid.
• Full Hybrid Electric Vehicles (FHEVs) have larger battery packs and more powerful electric motors than mild hybrids and can travel short distances at low speeds on battery power alone.

While PHEVs have few applications and are almost exclusively used in cars, HEVs are often seen in buses due to their high fuel savings potential in urban areas.

Conclusion:

HEVs also offer a familiar driving experience similar to that of ICE vehicles. They can be refuelled at conventional petrol stations and do not require a special charging infrastructure, making them convenient for users who may have limited access to charging stations. HEVs eliminate range anxiety because the internal combustion engine eliminates concerns about running out of charge.

It’s important to note that HEVs still rely on fossil fuels and have a limited all-electric range. However, they could play an important role in the transition to a sustainable future by encouraging the use of electric propulsion and familiarising users with hybrid technology. As BEV technology develops and charging infrastructure expands, HEVs could act as a ‘bridge technology’, allowing consumers to gradually adopt E-Mobility before moving to full electric vehicles.

While HEVs have their advantages as a transitional technology, the full adoption of BEVs represents a more significant step towards reducing dependence on fossil fuels, minimising emissions and moving towards a more sustainable transport future.

It’s worth noting that individual circumstances such as driving patterns, access to charging infrastructure and personal preferences may still influence the choice between BEVs and HEVs. However, as the technology continues to evolve, the advantages and benefits of BEVs make them a compelling choice for those seeking to maximise environmental sustainability, energy efficiency and long-term cost savings in the field of E-Mobility.

All in all, these hybrid vehicles will help us make the ultimate transition to pure electric vehicles. In the meantime, they allow us to save some fuel and reduce emissions while we work around and find solutions to limiting factors such as range and charging infrastructure.

References:

Spendiff-Smith, M. (2022)  Electric vehicles types – a complete guide to types of EV – EVESCO. Power Sonic. Retrieved from: Link

www.emobil-umwelt.de – Umweltbewertung Elektromobilität – FREQUENTLY ASKED QUESTIONS