The application considered here is a subway bogie designed by Bombardier Transport for the city of Caracas (Venezuela). Unlike a classical bogie, this one has an articulated chassis separated into two longitudinal parts assembled by a central joint allowing for left/right relative pitch. Actually, this joint is made out of rubber and six relative degrees of freedom (d.o.f.) exist between the two parts of the chassis.
Two three-phase induction motors are coupled with the axles by means of reducers. These motors are supported by the chassis at two specific locations:
Subway bogies are commonly driven by DC-motors, but in this case, the motor manufacturer proposed to replace them by three phase inductive motors. The latter are characterized by important torque oscillations when starting and Bombardier’s engineers were worried about possible additional vibrations of the chassis, due to these torque oscillations. Indeed, additional vibrations could lead to fatigue issues, which should be avoided. The main objective in studying this bogie was thus to analyze the influence of the torque oscillations during starting of the bogie.
To achieve this goal, a strongly-coupled electro-multibody model was developed in Robotran using an original Lagrange formulation, involving both mechanical and electrical generalized coordinates.
Fortunately, after comparing the results with those obtained with classical DC-motors, we could not conclude for significant additional vibrations induced on the chassis of the bogie, when introducing three phase actuators.