Volvo develops range extender that can extend electric vehicle range to 1,000 kilometers

Volvo Cars is taking the next step in its electrification strategy by building a demonstrator vehicle with a Range Extender, which equips an electric car with an internal combustion engine to increase its effective range.

The project, which is supported by the Swedish Energy Agency and the European Union, includes three high-potential technology packages. According to the plan, various concept technologies will begin testing in the first quarter of 2012.

Derek Crabb, Vice President of Powertrain Design at Volvo Cars, said: "Volvo is increasingly focusing on vehicle electrification, and the range extender for electric vehicles is an exciting technological development. With the range extender, the effective range of electric vehicles can be increased by up to 1,000 kilometers, while the carbon dioxide emissions level will be controlled below 50 grams per kilometer, or even much lower than this."

As mentioned above, the company's current technology development in this area revolves around three different technology combinations. A three-cylinder gasoline engine is installed on an auxiliary electric drive (front-wheel drive). All derivative models have brake energy regeneration. This three-cylinder gasoline engine has dual-fuel performance and can use gasoline or E85 ethanol fuel. Two of the technical solutions are based on the Volvo C30 Electric Vehicle. The original standard battery pack will be reduced in size to make room for the internal combustion engine and fuel tank.

Below, these three technology combinations will be introduced one by one:

Technology concept 1: Volvo C30 equipped with a series-connected range extender

Figure 1 is a schematic diagram of the Volvo C30 equipped with the tandem range-extending concept technology. However, this diagram is mainly used to describe the functional and structural characteristics of the new technology, rather than an accurate technical solution diagram. For example, the selection of the background model is not strictly arranged according to the C30 or V60. The text on the left side of the figure is from top to bottom: three-cylinder gasoline engine, fuel tank (40 liters), electric motor; the text on the right side is from top to bottom: generator, battery.

Figure 1: Concept I of range-extended technology for electric vehicles developed by Volvo Cars

The first series range-extending technology concept is based on the Volvo C30 electric car. A 45 kW (60 hp) three-cylinder gasoline engine is installed on the floor of the rear cargo compartment, and a 40 kW (53 hp) generator is closely connected in front of it. In front of the generator is a 40-liter fuel tank, which provides energy for the gasoline engine. In front of the fuel tank are the battery pack and the main electric motor, respectively. The entire power mechanism presents a straight series layout, but the "series" here actually focuses more on the linkage of the two powers, that is, the internal combustion engine power is only used for power generation and is not directly driven.

Figure 2: Volvo C30 electric car with charging cable

Figure 3: Derek Crabb, Vice President of Powertrain Design at Volvo Cars

The energy output by the engine is converted into electrical energy at the generator, which drives the main electric motor with a power of 82 kW (111 horsepower) in standard mode. After the battery pack is exhausted, the generator will directly provide electricity to the electric motor to continue to extend the driving range, thus extending the vehicle's electric propulsion range. However, while the battery pack is still running, the driver can also choose to use the generator to charge the battery pack, which is conducive to increasing the battery propulsion range in areas with low emission requirements, thereby meeting the requirements of reducing exhaust gas generation. The original on-board battery pack can provide a range of 110 kilometers on a single charge, which can be extended to 1,000 kilometers with the range extender.

Technology concept 2: Volvo C30 equipped with a parallel-connected range extender

Figure 4 is a schematic diagram of the Volvo C30 equipped with a parallel range extender concept technology. The captions on the left side of the figure are from top to bottom: three-cylinder gasoline engine, fuel tank (40 liters), electric motor; the captions on the right side are from top to bottom: generator, gearbox, battery.

Figure 4: Range-extended technology concept II for electric vehicles developed by Volvo Cars

The parallel range-extending technology concept is also based on the Volvo C30 electric car. The layout is similar to the series range-extending technology concept, except that a six-speed automatic transmission is set on the left side of the generator. The three-cylinder gasoline engine used in the vehicle here is equipped with a turbocharger and has a power of up to 190 horsepower, which is far more than the series type, and can realize the mode of two power sources working in parallel.

The same concept as the series range-extending technology, the standard mode is still the generator providing energy to the electric motor to extend the range. In the urban driving mode, the generator can also charge the battery, extending the working time and range of the battery pure electric propulsion to meet the regulations of low-emission areas.

In the newly added parallel working mode, the power of the three-cylinder gasoline engine can drive the rear wheels of the vehicle through the regulation of the six-speed automatic transmission. Taking into account the power of the electric motor of 111 horsepower, the total power of the entire vehicle exceeds 300 horsepower, giving the car an acceleration performance from rest to 100 kilometers per hour in 6 seconds. Therefore, this parallel working mode that achieves maximum total power is also called Sport Mode.

Equipped with a more powerful gasoline engine, the new car has paid a small price in weight, and the pure electric mode propulsion distance after a single charge is 75 kilometers. However, after starting the extended range function, the maximum range can still exceed 1,000 kilometers.

Figure 5: Volvo C30 electric car connected to the charging cable

Figure 6: The Volvo C30 electric car is painted in Cosmic White, while the front and sides of the R-Design body components are painted in Orinoco Blue.