News from the Startup Garage BMW tests electric motor with double rotor

Related Vendors

DeepDrive GmbH

FAULHABER Drive Systems

Wuxi InfiMotion Technology Co., Ltd.

In its quest for innovative vehicle concepts, BMW launched the Startup Garage, which fosters potential startups and long-term strategic partners. One of these innovative products is now being tested on the road, showcasing the program's success in integrating groundbreaking technologies into BMW's future vehicles.

At the IAA 2021, BMW and the startup Deepdrive first met. Now, after further years of development, the first BMW with a drive from the startup is going on a test drive. But what is special about the drive concept?

The double rotor

Conventional electric drives are designed either as inner runners or outer runners. That means, the rotor either runs inside the stator or around the stator. The dual rotor now combines both in one concept. The stator is centrally located and surrounded by permanent magnets on both sides. The advantage is not only in efficiency. These two rotating elements of the drive work together here to maximize the magnetic flux within the motor. The magnetic flux runs from the inner rotor through the stator to the outer rotor and then back to the inner rotor. This forms a closed magnetic circuit.

The acoustics also benefit from lower noise emissions. Thanks to the lower torque ripple, the drive runs smoother.

The drive also features an integrated silicon carbide inverter (SiC), which further improves efficiency and reduces losses. This technology enables higher performance and less heat generation, optimizing the overall performance of the drive.

High torque and power density

The motor achieves an exceptionally high torque density. The manufacturer specifies the performance data of the hub motor as 2,400 Nm of torque and 250 kW in the 20-inch version. Per wheel, of course. The advantage of the concept is that due to the higher torque density, the weight decreases compared to conventional motors. Since the weight can quickly become a problem due to the unsprung mass especially with hub drives, this is extremely important. The motor weighs in at 27 kilos (59.5 lbs) and achieves up to 97 percent efficiency.

176.37In addition to the hub variant, there is also the Central Drive. The two drives from the series are significantly more cost-efficient (up to 30 percent), have very low iron losses and require 50 percent less magnetic material compared to motors with similar performance. With 4,800 Nm of torque (EDU Torque, Electric Drive Unit Torque), 350 kW, and an efficiency of 96 percent, the drive weighing less than 80 kilos (176 lbs) including inverter, excluding transmission) provides more than enough power for most vehicles.

Summary

The startup is developing exciting motors that save 50 percent magnetic material and 80 percent iron. In this way, the costs in the concept patented by Deepdrive are reduced by up to 30 percent per Newton meter of torque. Series production is planned for 2025. Whether the engines are used in BMW vehicles is now being shown in the test drives. Even though it sounds unusual that BMW would buy engines. Ultimately, the parts installed are only an interim goal for the final product. It is not yet known for which model series the drive is being tested. (mr)