Method of operating an engine assembly

An engine assembly comprising:

• an engine;
• a turbocharger assembly, a control parameter of the turbocharger assembly being controllable in order to control a level of boost provided by the turbocharger assembly;
• and
• one or more controllers configured to;
• determine a desirable pressure limit of exhaust gases upstream of a turbine of the turbocharger assembly;
• predict a desirable limit value of the control parameter to be applied to the turbocharger assembly in order to achieve the desirable pressure limit;
• predicting a current value of the control parameter based on a current pressure of exhaust gases upstream of the turbine;
• determining a current value of the control parameter;
• and determining the error in the desirable limit value of the control parameter as being between the predicted current value of the control parameter and the current value of the control parameter;
• determine an error in the desirable limit value of the control parameter;
• adjust the desirable limit value of the control parameter based on the error;
• and
• control operation of the turbocharger assembly such that the adjusted desirable limit value is not exceeded.

A method of operating an engine assembly, the engine assembly comprising:

• an engine;
• and
• a turbocharger assembly, a control parameter of the turbocharger assembly being controllable in order to control a level of boost provided by the turbocharger assembly, wherein the method comprises:
• determining a desirable pressure limit of exhaust gases upstream of a turbine of the turbocharger assembly;
• predicting a desirable limit value of the control parameter to be applied to the turbocharger assembly in order to achieve the desirable pressure limit;
• determining an error in the desirable limit value of the control parameter;
• predicting a current value of the control parameter based on a current pressure of exhaust gases upstream of the turbine;
• determining a current value of the control parameter;
• and determining the error in the desirable limit value of the control parameter as being between the predicted current value of the control parameter and the current value of the control parameter;
• adjusting the desirable limit value of the control parameter based on the error;
• and
• controlling the operation of the turbocharger assembly such that the adjusted limit value is not exceeded;
• wherein the operation of the turbocharger assembly is controlled according to a minimum of:
• a desired value of the control parameter;
• and
• the adjusted desirable limit value of the control parameter.