Modelling of inverter-controlled asynchronous drives for system simulation in DC railways

AC inverter drives are being increasingly used for DC-supplied railways. Since simulation techniques are now routinely used for the system design of railways, there is a need to accurately model this type of equipment which is being introduced by several railway organisations. This paper describes models developed for representing the tractive effort and the DC electrical terminal characteristics of inverter-controlled asynchronous drives, for the variable voltage conditions encountered in DC-supplied railways. The models are based upon closed-loop control strategies normally used for traction inverter drives. The models can also be used, with minor modifications, when asynchronous AC drives are used for AC-supplied railways.