Powertrain system for a vehicle

A method for controlling a compressor assembly of a powertrain system for a vehicle, the powertrain system comprising an engine operable on a gaseous fuel, a gaseous fuel tank system having a set of gaseous fuel tanks for storing pressurized gaseous fuel, the gaseous fuel tank system being configured to be in fluid communication with the engine, and further the compressor assembly for pressurizing gaseous fuel, the powertrain system being operable in a first powertrain operational mode, in which gaseous fuel is supplied from at least one of the gaseous fuel tanks of the set of gaseous fuel tanks to the engine in a non-operational mode of the compressor assembly, and in a second powertrain operational mode, in which gaseous fuel from at least one of the gaseous fuel tanks is pressurized by the compressor assembly in an operational mode of the compressor assembly, and supplied to the engine, the method being implemented by a controller having a processing circuitry, wherein the method comprises:

• predicting, based on a current engine efficiency parameter and data indicative of at least one pressure level of at least one gaseous fuel tank of the set of gaseous fuel tanks, a first potential change in the engine efficiency for the first powertrain operational mode;
• predicting, based on the current engine efficiency parameter, data indicative of at least one pressure level of at least one gaseous fuel tank of the set of gaseous fuel tanks, and a needed power output from the engine for operating the compressor assembly to provide a predetermined pressure fuel level, a second potential change in the engine efficiency for the second powertrain operational mode;
• comparing the predicted first potential change in the engine efficiency with the predicted second potential change in the engine efficiency;
• and
• controlling the compressor assembly based on the comparison.