German automotive supplier ZF has developed a high-speed electric drive that is nearly 25% smaller and lighter than its existing system, while using half as much magnet material.
Called the High Revolution Drive, the three-in-one unit combines an electric motor, inverter and transmission. Its motor spins at up to 30,000 rpm, compared with 18,000 rpm for the equivalent ZF SELECT drive.
The higher rotational speed allows the motor to deliver the same power with less torque, reducing the size of the rotor.
A two-stage helical gear transmission with a ratio of around 18:1 then converts the motor’s high speed into the torque needed at the wheels.
The version demonstrated produces 200 kW (272 PS) and 3,500 Nm of peak wheel torque. ZF claims an efficiency of nearly 93%, matching its existing SELECT system despite the increased motor speed.
ZF also claims the new design reduces system costs by 13%, partly through lower material requirements.
High-speed motors present additional challenges in controlling noise and vibration. ZF said it addressed these by developing the motor, gearing and bearings together rather than treating them as separate components.
The drive is intended for mass-market electric cars with outputs between 150 and 200 kW. It can be adapted for both 400V and 800V electrical architectures.
Built around ZF’s modular SELECT platform, the technology allows manufacturers to adopt the smaller drive without developing an entirely new system.
ZF is discussing the technology with several carmakers and aims to begin production by 2030.
