Electric drive systems have been continuously optimized for years to improve their electrical, mechanical and electronic components. Reflecting on the market changes and considering customer requirements, more and more innovative and efficient concepts are emerging. Our hofer powertrain EDU portfolio covers a wide range of solutions for both basic and unusual applications.
The variety of solutions comes with several possible layouts. A key distinction is made between axially parallel, coaxial and dual-coaxial variants. The availability of installation space is a decisive factor in choosing the right layout to achieve desired results.
All our Electric Drive Units are designed to be compact and offer high versatility in transmission ratios, speeds and voltages. For specific use-cases, where space is prioritized, we raise the level of energy-density even higher to suit the design specifications.
Coaxial Electric Drive Units
The coaxial EDU variant is an electric drive unit that offers different power and torque intensities and ensures a high level of efficiency. It can serve a range of applications and brings great flexibility to implementation. Due to its inline structure, it enables most consistent and effective use of installation space, with the inverter occupying the space centered above the electric machine.
Axially parallel Electric Drive Units
This EDU variant is characterized by a parallel-axis structure in which the shaft output of the transmission is positioned with an offset to the shaft output of the motor. Thanks to its compact design, this variant can be easily integrated into various electric vehicle platforms, where coaxial structure is not an ideal fit. Components developed for coaxial design mostly have a similar design and can be assembled in the axially parallel layout, which helps to reduce the development effort.
Dual-axially parallel Electric Drive Units
High-performance requirements and unique demands with respect to driving dynamics call for special solutions. With this in mind, a compact design was developed combining two independent drives in a single package. This solution enables torque vectoring functions, which distribute torque between the individual wheels allowing excellent handling and control of the vehicle.
With this system, hofer powertrain is presenting a highly integrated drive unit concept, successfully realized through particularly close synergy between the e-machine, the inverter, and the transmission. This e-machine design increases the power and torque densities available on the market for electric drives. Our goal was achieved by cleverly combining a high-current inverter with a finely balanced stator winding system using hairpin technology.
Our ONEbox shines with a high peak power that meets the dynamic driving requirements of modern electric vehicles. The design balances a high torque in the lower speed range with a high efficiency in the medium speed range. Despite a high-power output, the concept keeps the promise of excellent NVH behavior. During the entire development, minimizing the overall dimensions and size was prioritized - the integrated cooling system is designed to be as compact as possible.
Thanks to its robust design, the complete drive can be installed in a various vehicle, including off-road SUVs. The highly protected case is resistant to external influences such as heavy rain, dirt and dust - even when placed in water, it wouldn't be an issue for this EDU solution.
To be prepared for any driving situations, both intended and unforeseen, the power electronics use our innovative software tailored to control the powertrain effectively at any given moment.
Standardized and efficient off-the-shelf drive unit (EDU150-O-330)
The axis of this drive solution was developed to meet the highest standards of Noise Vibration Harshness (NVH) and operational efficiency. The permanent-magnet synchronous machine is connected to a 1-speed, two-stage gear system. The gearbox has a ratio of 9.53 and thus permits speeds of around 1420 rpm. It contains an open differential, which enables the vehicle to go up to 153kW (at 400 volts DC) peak power and 3350Nm peak torque.
The innovative traction inverter features our next generation ONEboard solution which incorporates the drive board and control board on a single PCB. Developed from scratch, our inverter is located centrally above the electric motor.
Our "People Mover" level 5 autonomous-ready EDU solution (EDU130-I-240)
The main focus of this EDU was a never before seen, 600.000 km, long operating lifetime. This is complemented by an even greater reduction in service requirements as well as any vibrations and noise in the vehicle (Noise Vibration Harshness, NVH).
This EDU model is a high-power, high-torque electric drive unit with a gear ratio of 11.9, promising a high efficiency factor. Based on the coaxial principle, this solution is ideally suited for mid-range electrification applications with up to 150 kW of peak power and 75 kW of continuous mechanical power with its maximum torque around 2500Nm.
Due to high power availability, robust design and high-power density, this solution is best suited for busses and new electric "people mover" vehicles. Moreover, the software and the safety systems have been developed according to the latest automotive standards, enabling vehicle manufacturers to achieve level 5 of autonomous driving, thus paving the way for the mobility of the future using this solution. Another autonomous-ready feature is a hydraulically actuated disconnect clutch on the differential, which is capable of disengagement and is important for the safety-critical functions.
Whether as an add-on solution for existing vehicles or for new purely electric models, this drive unit has proved to be an ideal solution for a variety of new age electric concepts.
Enhanced stability and curve control at high speeds - EDU with torque vectoring function (EDU300-DO-330)
At the peak of high-performance solutions, this fully integrated 6in1 electric drive unit shines with the ability to supply different torque values to each wheel for outstanding handling in even the steepest curves. The transmission with a ratio of 8.5 offers best-in-class efficiency. Designed for high-performance electrification purposes with up to 300 kW peak power and 150 kW continuous power, the system is an ideal centerpiece for sports vehicles promoting electrification on and off the racetrack.
Looking ahead to the next part of this EDU article series as part of our Electrification Weeks, experts at hofer powertrain will be providing detailed insights into the complete EDU development processes from concept design to series production. In addition, based on extensive experience, we will shed light on various future topics and technologies, present crucial test and analysis tools, talk about thermal management techniques, such as oil cooling and many more.