Sensorless control of a 2.4MW linear motor for launching roller-coasters

An accurate method for estimating the position of a large Linear Synchronous Motor, based on on-line measured phase currents and voltages is shown. Synchronous frame filters remove the fundamental component from these signals effectively, even during fast acceleration. The proposed correlators estimate local parameter values, inductance and resistance, from the remaining switching ripple signals with high bandwidth, able to follow the abrupt changes caused by block switching of the long stator. Experimental results show that a controlled start from standstill is possible.