Technology

Various Options for More Range

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Tags: Emobility, #MobilityLifeBalance

Increasing the battery capacity is not enough to get electric cars to travel farther. ZF is making numerous adjustments to the driveline to get maximum mileage out of a battery charge.
Kathrin Wildemann, September 30, 2019
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Kathrin Wildemann has been a part of the permanent Copy Team at ZF since 2016. In her online and offline articles, she likes to cover electromobility and other topics that involve sustainability.
When people are asked about the main reasons that prevent them from switching to an electric vehicle, drivers usually mention the significantly higher acquisition costs and the range of electric cars, which is too short when compared to drive systems based on internal combustion. While the first point of criticism is only gradually disappearing as the quantity of vehicles manufactured increases, ZF is already in the process of doing away with the second obstacle. The technology company’s developers are taking several approaches to achieving this goal.

Perfectly matched drive components

Perfectly matched drive components

The range can of course be increased by installing a bigger battery. However, the consequences are less space for passengers and luggage, greater vehicle weight, and higher acquisition costs. It makes more sense to design all components of the driveline as well as possible and to coordinate them perfectly with each other, which is the approach ZF is taking. In this way even supposedly small optimizations can bring about a noticeable overall increase in efficiency. Bert Hellwig, Head of the E-Mobility system house at ZF, says: “For everyday use of electric cars, it is important to get as much range as possible from a single battery charge. Each percent of energy conversion efficiency gained results in two percent more range.”
For example, an inverter with power electronics that is well matched to the drive system contributes to optimum use of the available energy. These components control features such as energy regeneration (recuperation) during braking.
“For everyday use of electric cars, it is important to get as much range as possible from a single battery charge. Each percent of energy conversion efficiency results in two percent more range.”
— Bert Hellwig, Head of the E-Mobility system house at ZF

Low-resistance power electronics for covering more miles

Low-resistance power electronics for covering more miles

In this field, ZF benefits from its commitment to motorsports, where the pressure to innovate is particularly high: in Formula E, efficiency is the crucial factor. For the 2018/2019 season, ZF developed the entire driveline of the Venturi team. In order to achieve maximum performance, the engineers for the first time used silicon carbide instead of the usual silicon as the semiconductor in the power electronics. Silicon carbide can be used to make chip sets 10 times thinner. This is advantageous because the internal resistance of the power electronics decreases and the efficiency and range of the vehicle increases. The Group now plans to incorporate this innovation into its volume production technology.
Semiconductors made of silicon carbide in the power electronics lower the resistance compared to conventional silicon semiconductors, thus increasing the efficiency and range of electric drives.
Power electronics: an increase in range of up to 10 percent due to silicon carbide.

Multiple benefits thanks to electric motor and transmission

Multiple benefits thanks to electric motor and transmission

An additional approach to increasing efficiency in e-mobility builds on the Group’s extensive expertise in transmission technology: ZF developers have equipped a new, compact electric car drive with a two-speed transmission. “With two gears, we can achieve better acceleration and a higher maximum speed. Another reason for the two-speed transmission was to increase the efficiency of the drive,” says Dr. Stephan Demmerer, Head of Advanced Engineering E-Mobility, adding: “With this combination of a special electric motor with a two-speed transmission, we achieve an optimal system with maximum efficiency.”
The new two-speed electric drive with a maximum output of 140 kilowatts allows a passenger car to be driven at higher speeds with much greater energy efficiency than is the case with conventional electric vehicles. At the same time, the electric vehicle does not lose traction at lower speeds. Together with the integrated power electronics, the electric drive with a shift element ensures an increase in range of up to five percent.
Electric two-speed drive from ZF: more efficiency and range due to transmission.

Versatile use of the electric two-speed drive from ZF

Versatile use of the electric two-speed drive from ZF

This driveline from ZF opens up various application options for automotive manufacturers. For example, they can offer vehicles featuring an extended range with the same battery size, counteracting the primary concerns of many customers. The efficiency gain also allows the drive to be combined with a smaller battery, saving money, installation space, and weight, which benefits price-sensitive subcompact and city cars in particular. The modular two-speed drive is also aimed at manufacturers that focus on performance. Until now, electric drives were associated with a choice between a high starting torque and a high top speed. Together with a powerful electric motor of up to 250 kilowatts, the new drive concept provides enough power to ensure that drivers of sporty or heavy-duty vehicles do not have to make compromises when starting off or when driving at top speed.
Shifting to second gear at 70 km/h: the two-speed drive for passenger cars.

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