eMotors for automotive drivetrains

News Editor

BorgWarner produces two types of eMotor for automotive drivetrains: the Permanent Magnet Synchronous Machine (PSM), also known as an Interior Permanent Magnet (IPM) motor, and the Induction Machine (IM). Either hairpin or S-Wind winding technology can be applied to these, with different outcomes in terms of physical form/size, power density, and electrical efficiency at different motor speeds.


Hairpin technology is widely acknowledged as the state-of-the-art winding method, its primary advantage being high efficiency at low speeds. The manufacturing process is more complex than for other winding technologies – each individual hairpin must be twisted and welded to form the winding – but BorgWarner’s innovative production methods and equipment offset this.

BorgWarner’s latest high voltage hairpin (HVH) stator winding technology delivers industry-leading power density, and peak efficiencies greater than 97%. HVH series eMotors are available in various stack length, cooling and winding configurations, as fully housed motors or rotor/stator assemblies.


S-Wind allows shorter winding heads, reducing motor length without losing performance. It can also increase the number of conductors per slot, for superior continuous high speed power delivery at the same Worldwide Harmonized Light Vehicles Test Procedure (WLTP) cycle efficiency as hairpin technology.

Since BorgWarner began using S-Wind technology in 2012, it has featured in all of the manufacturer’s S-series alternators. Developed further for use in eMotors, S-Wind Gen2 was put into large scale production for P2 48V drive modules for hybrid electric vehicles. The first application for the latest generation S-Wind Gen3 is P3 48V traction motors.

eMotor cooling

Various strategies are available to cool an eMotor depending on customer requirements. Among these are water-ethylene glycol (WEG) jacket cooling, oil spray and splash cooling including oil flow through the rotor lamination stack, hybrid cooling strategies using a combination of WEG and oil, and concepts based on motor stator back-iron oil cooling.

eMotor applications

For hybrid/plug-in hybrid electric vehicles (PHEV) or battery electric vehicles (BEV), BorgWarner eMotors are used as traction motors. For hybrids/PHEVs, the eMotor is integrated in a dedicated hybrid transmission (DHT), either by the vehicle OEM or the transmission manufacturer. For BEVs, the eMotor is a component of an integrated drive module (iDM), assembled either by BorgWarner or by the vehicle OEM during series production. In addition to passenger car applications, these eMotors are also used in commercial vehicles such as trucks or buses.

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