Compressor for exhaust treatment system

An exhaust aftertreatment system for an engine is provided that includes a burner, an air supply system and a control module. The air supply system may be in fluid communication with the burner and may include an air compressor disposed upstream from the burner. The air compressor may include a pump mechanism, a clutch assembly selectively transferring torque from the engine to the pump mechanism, and a motor selectively driving the pump mechanism. The control module may be in communication with the clutch assembly and the motor. The control module may selectively switch the air compressor between a first operating mode in which the clutch assembly transfers torque from the engine to the pump mechanism and a second operating mode in which the motor drives the pump mechanism.