High Density, High Efficiency Electrical Power Generation

Electrical power generation systems have inherent inefficiencies due to electrical and mechanical loss mechanisms. These inefficiencies mostly stem from generator core and copper losses, eddy current losses, and mechanical losses (bearings, rotating seals and windage). These inefficiencies raise the generator temperature, mostly the stator and rotor, as well as increase the aircraft heat load, requiring larger and heavier heat exchanging systems. Heat, which is the direct product of inefficiency, is the main reason for limiting generator output. The insulating and encapsulating materials inside the generator, are limited to operating at a maximum temperature of 220degreesC. Therefore, the key to increasing power density lies in improving efficiency and improving cooling. Improved efficiency is the outcome of the generator electromagnetic design combined with the type of cooling method chosen for the specific application. IPS has developed several oil cooled generators utilizing improved cooling techniques to maximize power density. IPS has a patent for cooling rotors in conduction oil cooled generators. This patent is used in the Global Hawk UAV generator, and allows continuous operation at elevated temperatures to 700degreesF, and is also used to increase the power rating of a 650 Amp, 28 Vdc generator to 1000 Amp in the same envelope.