Thrust and lift control of the MAG-transit vehicle

MAG-TRANSIT is a unique combination of magnetic levitation and propulsion for people mover applications. Linear induction motors are used for levitation, propulsion, braking and guidance. Since there are a minimum of moving parts, there is a potential for a substantial increase in system reliability and availability as compared to conventional systems. This paper provides an overview of the algorithms used for thrust and lift control of a MAG-TRANSIT vehicle which is being developed by Boeing Aerospace Company under a US Department of Transportation/UMTA contract. Since the AC linear induction motors (LIM's) are used for both propulsion and levitation, the control algorithms have been designed to minimize interactions between thrust and lift. Motor frequency is used to control thrust and voltage to control lift. Normal braking effort is provided by regenerative LIM operation. The results of longitudinal (thrust) and lift simulations are presented. Time histories of key variables are shown for an accelerate-cruise-decelerate command sequence. The lift analysis procedure involves driving the dynamic vehicle simulation models by a guideway roughness model to generate accelerations for ride quality analysis and dynamic air gap estimates for air gap budgeting analysis.