Systems and methods for controlling exhaust gas recirculation

An engine system comprising:

• a first cylinder group including at least one first cylinder;
• a second cylinder group including at least one second cylinder;
• an intake manifold coupled to the first cylinder group and the second cylinder group;
• a first EGR passage coupled between the at least one first cylinder of the first cylinder group and the intake manifold;
• an EGR cooler coupled in the engine system;
• a second EGR passage coupled between the at least one second cylinder of the second cylinder group and the intake manifold;
• a first EGR valve, positioned in the first EGR passage, operable to control exhaust gas flow to the intake manifold;
• a second EGR valve, positioned in the second EGR passage, operable to control exhaust gas flow to the intake manifold;
• a controller operable to backpressure only as many cylinder groups of the first cylinder group and the second cylinder group as needed to provide a commanded EGR gas flow, including the controller being operable to:
• during a first condition, adjust only one of the first EGR valve and the second EGR valve and close the other of the first EGR valve and the second EGR valve;
• and
• during a second condition, fully open one of the first EGR valve and the second EGR valve and adjust the other of the first EGR valve and the second EGR valve, wherein the controller is operable to adjust only one of the first EGR valve and the second EGR valve and close the other of the first EGR valve and the second EGR valve, to provide a first EGR gas flow to the intake manifold that is less than a maximum capable EGR gas flow that one of the first cylinder group or the second cylinder group can supply, and fully open one of the first EGR valve and the second EGR valve and adjust the other of the first EGR valve and the second EGR valve, to provide a second EGR gas flow that is greater than the maximum capable EGR gas flow that one of the first cylinder group of the second cylinder group can supply;
• a first exhaust manifold coupled to the first cylinder group and not the second cylinder group, the first EGR passage coupling the first exhaust manifold to the intake manifold;
• a second exhaust manifold coupled to the second cylinder group and not the first cylinder group, the second EGR passage coupling the second exhaust manifold to the intake manifold;
• a first exhaust passage coupled between the first exhaust manifold and an exhaust pipe;
• a second exhaust passage coupled between the second exhaust manifold and the exhaust pipe;
• a first exhaust valve, positioned in the first exhaust passage, operable to control exhaust gas flow from the first exhaust manifold to the exhaust pipe;
• and
• a second exhaust valve, positioned in the second exhaust passage, operable to control exhaust gas flow from the second exhaust manifold to the exhaust pipe;
• the controller being operable to adjust one of the first exhaust valve or the second exhaust valve and close the other of the first exhaust valve and the second exhaust valve, to provide the first EGR gas flow, and adjust one of the first exhaust valve or the second exhaust valve and fully open the other of the first exhaust valve and the second exhaust valve, to provide the second EGR gas flow.