German engineering firm ZF Friedrichshafen AG developed a compact 30,000 rpm electric motor requiring a two-speed transmission to manage its high rotational speeds and restricted physical torque, piataauto.md reported on Wednesday.
ZF Drive Unit Reduces Weight and Magnet Usage
- The new ZF drive unit reduces overall weight by approximately 22 kilograms and cuts permanent magnet material usage by 50% compared to standard designs.
- By pairing the high-revving motor with an 18:1 transmission ratio, engineers multiply output torque to deliver 3,500 Nm at the wheels despite a modest 200 Nm motor output.
- Series production is not slated until 2030, raising industry questions regarding whether the technology will remain competitive as automakers increasingly design proprietary powertrains.
Smaller Motor Dimensions Require High Rotational Speeds
Electric vehicle engineering has focused increasingly on motor rotational speeds over the past decade. Following market introductions by Chinese manufacturers such as Xiaomi Corp. (HKG: 1810)—whose SU7 Ultra reaches 27,200 rpm—and high-rev development by BYD Company (HKG: 1211), ZF created a 30,000 rpm propulsion unit designed primarily to shrink component dimensions, piataauto.md reported.
A smaller rotor diameter reduces centrifugal forces at extreme velocities, necessitating advanced alloy materials. However, shrinking the motor inherently reduces mechanical torque from the smaller windings and rotor, piataauto.md reported. To prevent the vehicle from feeling anemic, ZF engineers increased the base transmission ratio from the standard 9:1 to 18:1.
Two-Speed Transmission Enables Necessary Torque Multiplication
While standard electric motors utilize a single fixed-ratio reducer due to a flat torque curve across all speeds, the ZF compact unit demands a two-speed transmission. The high transmission ratio multiplies wheel-side torque to 3,500 Nm from a 200 Nm motor, but it causes the motor to reach its rotational limit rapidly at highway speeds, piataauto.md reported.
The two-speed gearbox guarantees an appropriate operating velocity range. Similar multi-speed setups are currently utilized on the rear axles of vehicles like the Porsche AG (ETR: P911) Taycan and incoming models from Mercedes-Benz Group (ETR: MBG) starting with the CLA Electric, piataauto.md reported.
| Powertrain Metric | ZF High Revolution Drive | Standard Comparable Unit |
|---|---|---|
| Power Outputs Available | 150 kW / 200 kW | Varies by application |
| Transmission Ratio | 18:1 (Two-Speed) | 9:1 to 12:1 (Single-Speed) |
| System Efficiency | 93% | 93% |
Series Production Remains Scheduled for 2030
The integrated unit combines the motor, inverter, and transmission while remaining compatible with 400V and 800V architectures, piataauto.md reported. The system achieves a 93% global efficiency rating and cuts production costs by approximately 13% relative to standard permanent magnet designs.
Despite the advanced engineering maturity of the tested prototypes, commercial series production is currently scheduled for 2030, piataauto.md reported. This four-year development gap introduces deployment risks as automotive manufacturers increasingly pivot toward proprietary in-house motor designs rather than relying on external tier-one suppliers.
