The electric motor/generator is a custom made induction machine.
The torque/speed curve of the motor must be chosen in accordance with the application in order to provide sufficient power at low speed. Power range of the motor goes from 20 kW to more than 200 kW. The cooling of the motor is very important for a good and reliable operation: the motor is liquid cooled with an active cooling media temperature monitor. Thanks to the transmission gear unit, the speed of the electric motor can be higher than the Diesel motor speed allowing more power in the same frame size.
Depending on the application, the shape of the motor can be square or round assuring a good heat transfert from the rotor and stator to the cooling liquid. The motor design is also optimize to provide the best efficiency when used with a frequency inverter.
Generally, when the system is in Diesel mode, the motor is used as a generator generating energy to fill the batteries.