Method and architecture for supplying air to an auxiliary power unit of an aircraft

An architecture for supplying air to a high-pressure compressor of an auxiliary gas generator from a pressurized cabin of an aircraft, wherein the architecture comprises:

• a load compressor rotationally driven by a common rotation shaft providing a mechanical coupling between the high-pressure compressor and a high-pressure turbine of the auxiliary gas generator and supplied by an outside air intake;
• a first regulation valve assembled at an outlet of the load compressor to control all or part of air flow delivered by the load compressor;
• a second regulation valve assembled at an outlet of the pressurized cabin to control air flow drawn from inside the pressurized cabin;
• a mixer receiving outputs of the first and second regulation valves to add the air drawn from the inside of the pressurized cabin to all or part of the air delivered by the load compressor;
• and a third regulation valve assembled at an outlet of the mixer to control air flow injected into the high-pressure compressor of the auxiliary gas generator, wherein the architecture further comprises, assembled at an inlet of the high-pressure compressor, a selector valve to select the air with the highest pressure between the outside air intake and an outlet of the third regulation valve.