Variable geometry turbine and method for calibrating a variable geometry turbine

A variable geometry turbine (VGT), comprising:

• an intake channel, arranged for receiving a mass flow of exhaust gas from an internal combustion engine;
• a rotor, arranged downstream the intake channel for extracting energy from the mass flow of exhaust gas;
• an adjustable nozzle, comprising a nozzle orifice having an adjustable cross sectional area and arranged for adjusting the mass flow of exhaust gas from the intake channel to the rotor, wherein the adjustable nozzle is adjustable between an open position, in which the nozzle orifice has a maximum cross sectional area, and a closed position, in which the nozzle orifice has a minimum cross sectional area;
• a nozzle actuator, arranged for actuating the adjustable nozzle between the open position and the closed position;
• and
• a controller, arranged for controlling the nozzle actuator based on a nozzle position demand;
• wherein the controller comprises a calibration routine, arranged for calibrating the VGT during normal operation thereof;
• wherein, in the calibration routine, the controller is arranged for performing the steps of:
• adjusting the adjustable nozzle from an initial position towards the closed position, while monitoring a pre-turbine pressure measured in the mass flow of exhaust gas upstream the VGT;
• detecting a deflection point position of the adjustable nozzle at which a sharp difference in the pre-turbine pressure occurs;
• and
• adjusting a working range of the nozzle actuator, having an adjusted minimum cross sectional area in the closed position that excludes the detected deflection point position.