The present invention is related to power system architectures and in particular to pneumatic and electric power system architectures employed in aircraft.
Power distribution systems in aircraft operate to transfer energy from one part of the aircraft to another. Power can be distributed in various forms, including hydraulically, pneumatically, and electrically. Traditionally, there is little interaction between these systems. For example, the hydraulic distribution system does not interact with the electrical distribution system or the pneumatic distribution system. For example, one type of aircraft may rely mostly on pneumatic systems that distribute bleed air (e.g., compressed air generated by the aircraft engines) to various systems throughout the aircraft. For example, pneumatic power provided by an auxiliary power unit (APU) can be used to start a main aircraft engine. Pneumatic power provided by the main engine can be used to spin turbine and/or compressors associated with environmental control systems on the aircraft. However, the extraction of bleed air from the engine reduces the overall efficiency of the engine, particularly during certain flight segments. Furthermore, the distribution of pneumatic power requires large amounts of piping which increases the cost and weight of the aircraft, thereby further decreasing efficiency.
An alternative to pneumatic power is electrical power, which is generated by converting the rotational, mechanical energy associated with the aircraft engines and/or APU to electrical energy that is distributed throughout the aircraft. Instead of supplying pneumatic power to spin turbines and/or compressors associated with the environmental control systems, electrical energy is distributed to motors which in turn spin the turbines and/or compressors associated with the environmental control systems. However, torque generated by the electrical generator also contributes to decreased efficiency of the aircraft engine, particularly during certain flight segments.