Control device of an engine

A control system of an engine, the system comprising:

• a turbocharger having a turbine that is provided to an exhaust passage and a compressor that is provided to an intake passage,
• a turbine bypass passage for diverting exhaust around the turbine,
• a wastegate valve that is provided to the turbine bypass passage for controlling a flow rate of the exhaust flowing in the turbine bypass passage, and
• a control device executed on a processor including:
• a valve control part, executed on the processor, for performing a feedback control of a boost pressure of the turbocharger based on a deviation between a target boost pressure and an actual boost pressure, and
• a determination part, executed on the processor, for obtaining a target turbine flow rate that is a target value of the flow rate of the exhaust flowing to the turbine from the target boost pressure, for obtaining an exhaust total flow rate discharging from the engine, and for determining whether or not the exhaust total flow rate discharging from the engine in the exhaust passage is greater than or equal to the target turbine flow rate, such that the target boost pressure will be achieved, the target turbine flow rate being based on the target boost pressure,
• wherein the feedback control includes at least an integral term, and when the determination part determines that the exhaust total flow rate is smaller than the target turbine flow rate such that the target boost pressure will not be achieved, the valve control part controls an opening degree of the wastegate valve so as to reduce an influence of the deviation on a calculation of the integral term compared to that when the exhaust total flow rate is greater than or equal to the target turbine flow rate such that the target boost pressure will be achieved.