The Electric Variable Transmission

An Electric Variable Transmission (EVT) is an electromechanical converter with two mechanical ports and one electrical port (consisting of two concentric machines and two inverters). This converter works as a continuously variable transmission between the mechanical ports and may, e.g., replace the clutch, gearbox, generator, and starter motor in a motor vehicle.

EVT with permanent magnets

The activities on the field of the EVT with permanent magnets are concentrated in Electric Variable Transmission B.V.:



EVT with squirrel-cage windings

This EVT may be seen as built up from two concentric induction machines with a combined relatively thin yoke. Thus, we obtain one electromagnetic device
instead of two magnetically separated devices.



Kruse, Ralf; Salem Mourad; Darren Foster; Martin Hoeijmakers: Concept and Functionalities of the Electric Variable Transmission. 15th Aachener Kolloquium – Automobile and Engine Technology, 9-11 Oct. 2006, p. 1387-1398

Hoeijmakers, Martin J.; Jan A. Ferreira: The Electric Variable Transmission. IEEE Transactions on Industry Applications, vol.42, no.4, Jul/Aug 2006, p.1092-1100

Hoeijmakers, Martin J.; Jan A. Ferreira: The Electrical Variable Transmission. In: Conference Record of the 2004 IEEE Industry Applications Conference 39th IAS Annual Meeting, Seattle, Washington, USA, 3-7 october 2004, 04IAS70P7

Hoeijmakers, Martin J.; Marcel Rondel: The Electrical Variable Transmission in a city bus. In: Proceedings 2004 35th IEEE Power Electronics Specialist Conference, Aachen, Germany, 20-25 June 2004, p.2773-2778

EVT Java Applets and Applications

The applications below need the Java Runtime Environment (JRE:

  • EVT Animation (EVTAnimation.jar)
    This is an animation for the explanation of the EVT.
  • The EVT in a city bus (EVTDemo.jar)
    This is a simulation of the use of the EVT in a bus (in Dutch).
  • EVT Field (EVTField.jar)
    This is a 2D field computation.
    Input variables: The angle delta is the angle between the inner and the outer squirrel-cage flux linkages and has a relation with the input torque T_1 ; T_2 is the output torque; k_fs is proportional to the stator flux (field weakening).
    Output variables: I_r is the rotor current; I_ci is the current of the inner cage; I_co is the current of the outer cage; I_s is the stator current.
    T_1 is the input torque; omega_slip is the angular slip frequency; B_sPhi is the tangential stator flux density; B_yPhi is the tangential interrotor yoke flux density.

When the JRE has been installed under Windows they should run directy after clicking the link. After download, it may be run by a double click under Windows. In case a command line is used (also for Linux): java -jar ApplicationName.jar.

Electric Variable Transmission

Electric Variable Transmission

EVT Patent