Multiple Rotor Transmission

It doesn’t exist one electric motor that optimally FITS on all vehicles until today, everyone has worked around the electric motor and the transmission to maximize the overall efficiency of the electric vehicle. To do this, the customization was specific for each application and each specific working cycle.

IET, in its R&D department, worked around e-motor, designing, developing and then patenting the MRT™ (Multiple Rotor Transmission). MRT™ has been designed coupling two or more different e-motors and a gearbox with a unique output shaft. In this way has been reached an efficiency level previously unimaginable in a wider range of use cases and in a more safe and reliable way.


The MRT™ solutions allow to reach:

  • Greater degrees of freedom to be used in powertrain optimization
  • Increase in the overall efficiency of the motor
  • With the same current excitation is possible to develop higher torque at the same rpm, increasing the power
  • Increase of the safety: the system has an intrinsically redundant architecture that allow, in case of failure of one motor, to continue to work, with reduced performance
  • Better thermal management
  • 1.5 times the surface of a single motor that fits in the same volume
  • It is possible to command the motors in different way to avoid the thermal derating of the complete system

The advantage on thermal management can be spent to reach:

+  Higher power density
+  Better efficiency at the same power
+  Battery thermal management

–  Less cooling requirement
–  Less integration design

Code: MRT-INT-040-096 MRT-INT-080-096 MRT-000-080-096 MRT-000-120-096
Nr of Motor: 1 2 2 3
Motor: THREE phases Permanent magnet brushless motor AC
GearMotor Power: 40kW peak @103,6Vdc/ ≤450Arms /≤634Apeak 450Arms /≤634Apeak 450Arms /≤634Apeak 450Arms /≤634Apeak
Continuos power: 20kW (15 minutes) @96Vdc 40kW (15 minutes) @96Vdc 40kW (15 minutes) @96Vdc 60kW (15 minutes) @96Vdc
Motor Rpm Nominal @100Vdc: 6.500 rpm 6.500 rpm 6.500 rpm 6.500 rpm
GearMotor Torque: 180 Nm peak, 90Nm nominal 360Nm peak, 180Nm nominal 360Nm peak, 180Nm nominal 540Nm peak, 270Nm nominal
Mass: ≤40kg ≤40kg
Coolant: 50% aqueous Ethylene Glycol (OAT), Max. Pressure Drop: 0.15 bar @11.5 rpm, Max Pressure Coolant Circuit: 1.4 bar
Thermal: Max Coolant Temperature: 90°C Max Allowable Stator Temperature: 130°C Max
Efficiency: ≥90% @ 40kW ≥90% @ 80kW ≥90% @ 80kW ≥90% @ 120kW
Environmental Rating: IP67 IP67 IP67 IP67
Controller: VM-96-W-550 VM-96-W-550 NO NO
Contactor: YES YES NO NO
Connection: Nickel plate copper busbar Nickel plate copper busbar NO NO
Communication: Isolated CANOpen Isolated CANOpen NO NO