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Honeywell is working with Lockheed Martin and NASA to develop a lightweight, turbine-driven electric power generation system that offers greatly increased safety and reduced operating costs as compared to existing systems. The approach is to utilize a “bang-bang” speed control system with fuel-rich, catalytically-reacted hydrogen and oxygen propellants to drive a turbine and shaft-speed, high-reactance permanent-magnet generator. The rotating assembly is supported by gas-cooled “foil” bearings. The flight system is envisioned to be regeneratively cooled and have power conditioning and control electronics integrated within the pressurized turbogenerator housing. System definition and component development have been completed. “Brassboard” system testing is currently underway.

Launch vehicles that use electric actuators for thrust vector or flight control require a safe, reliable and lightweight source of electrical power. Honeywell, working with NASA Glenn Research Center and Lockheed Martin Space Systems, has developed and successfully tested a turbine-driven electric power generation system which meets these needs. This Turbine Power Unit (TPU) uses hydrogen and oxygen propellants which react catalytically to drive a shaft-speed turboalternator mounted on foil bearings. A high-reactance permanent-magnet machine (HRPMM) was selected for this application. The power conditioning and control electronics can be located within the TPU housing and the hydrogen fuel can be used to pressurize the bearings and electronics and to regeneratively cool the machine. A brassboard unit incorporating many of these features was successfully tested at output power levels from 0 to 138 kilowatts (kW).

The aircraft power and thermal management system (PTMS) developed by Honeywell combines the functions of an auxiliary power unit (APU), emergency power unit (EPU), environmental control system (ECS), and thermal management system (TMS) in one integrated system. For the F-35 aircraft this approach resulted in a substantial reduction in overall aircraft size and weight as compared to configurations using separate “federated” secondary power systems. Future aircraft incorporating the new more electric architecture (MEA) and energy efficient aircraft (EEA) initiatives are likely to benefit from this integrated approach as well, but they are also likely to require increased electric power generation capability, greater cooling capacity and higher operating efficiency.

In association with NASA Glenn Research Center and Lockheed Martin Space Systems, Honeywell has developed and successfully tested an electric power generation system that uses non-toxic hydrogen and oxygen propellants that are reacted catalytically. The resulting fuel-rich gases drive a turbogenerator. Speed control of this system is challenging due to highly variable electric load profile. Discrete two-position valves were used to control the propellant flow for improved reliability compared to proportional valves. This “bang-bang” speed control method exhibits variation in turbine acceleration and deceleration with load. The control thresholds for the turbine speed are adjusted based on load so as to compensate for increased speed overshoot and undershoot.