Method and system for emission control device heating

A method, comprising:

• via a controller, controlling each of a first flow control valve, a second flow control valve, and a third flow control valve, the first flow control valve and the second flow control valve coupled in series and configured to block or enable air flow from an engine intake to an engine exhaust passage upstream of a first emission control device, the third flow control valve coupled in series with the first flow control valve and coupled in parallel with the second flow control valve and configured to block or enable air flow from the engine intake to the engine exhaust passage upstream of a second emission control device, the controlling including:
• responsive to a first condition, adjusting the first flow control valve to a first open position selected at least partially based on a pressure in the engine intake, adjusting the second flow control valve to a second open position selected based on the first open position, the pressure in the engine intake, and a temperature of the first emission control device, and adjusting the third flow control valve to a third open position selected based on the first open position, the pressure in the engine intake, and a temperature of the second emission control device;
• and
• responsive to a second condition, fully closing or maintaining closed the first flow control valve, the second flow control valve, and the third flow control valve.

A vehicle system, comprising:

• an engine;
• a turbocharger including an intake compressor rotationally coupled to an exhaust turbine via a shaft and an electric motor;
• a wastegate valve coupled in a bypass around the exhaust turbine;
• an exhaust passage including a catalyst and a particulate filter, the catalyst coupled upstream of the particulate filter and downstream of the exhaust turbine;
• an air injection system for flowing intake air from an intake passage of the engine, downstream of the intake compressor, into the exhaust passage, upstream of each of the catalyst and the particulate filter, the air injection system including a first flow control valve coupled at an inlet of the air injection system, a second flow control valve coupled in series with the first flow control valve at a first outlet of the air injection system, the first outlet coupled to the exhaust passage upstream of the catalyst, and a third flow control valve coupled at a second outlet of the air injection system, the third flow control valve in series with the first flow control valve and in parallel with the second flow control valve, the second outlet coupled to the exhaust passage upstream of the particulate filter and downstream of the catalyst and parallel to the first outlet;
• and
• a controller storing executable instructions in non-transitory memory that, when executed, cause the controller to:
• operate in a first mode to provide the intake air to the engine and at least one of the catalyst and the particulate filter, where operating in the first mode includes operating the turbocharger via the electric motor with the wastegate valve fully open, adjusting the first flow control valve to a first open position selected at least partially based on a pressure in the intake passage, adjusting the second flow control valve to a second open position selected based on the first open position, the pressure in the intake passage, and a temperature of the catalyst, and adjusting the third flow control valve to a third open position selected based on the first open position, the pressure in the intake passage, and a temperature of the particulate filter, and operating the engine with a rich air-fuel ratio;
• and
• operate in a second mode to provide intake air to the engine only, where operating in the second mode includes operating the turbocharger with the wastegate valve at a position selected based on engine demand and fully closing or maintaining closed the first flow control valve, the second flow control valve, and the third flow control valve.