On the efficiency of asynchronous motors used in urban transportation systems

The paper presents a drive system consisting of an asynchronous traction motor and inverter used for trolley-buses. An analysis is made with respect to the exploiting of a traction drive system using the classic design (with d.c. motors), underlining the disadvantages of this type of driving The control of driving systems in a.c. is currently performed using modern techniques for vectorial control, allowing the increasing of their efficiency. A good practice is to start by analysing the feasibility of simple control strategies, requiring a small number of parameters. A series of simulations were made in order to analyze the motor´s behaviour in steady - state regime, with a simple variable speed control method. In the end possible explanations for the driving system efficiency reducing are discussed.