CONTROL OF INJECTION PRESSURE FOR HIGH PRESSURE DIRECT INJECTION SYSTEMS

The disclosure relates to a computer-implemented method for controlling direct injection of hydrogen fuel into an engine cylinder (103) of a vehicle (1) from a hydrogen tank (104) via an injector system (100), the method comprising: determining (S102) a present hydrogen pressure in the hydrogen tank (104); determining (S104) a present requested engine torque and speed; determining (S106) a target injection pressure for injecting hydrogen into the engine combustion chamber (103) using a model wherein the target injection pressure is the injection pressure that, according to the model (122), minimizes the mechanical work of the compressor (106), that provides an in-cylinder pressure sufficient for the engine to provide the requested engine torque and speed, that provides NOx emission below a predetermined maximum NOx emission level, and that reduces engine fuel consumption, and adjusting (S108) the injector pressure according to the determined target injection pressure.