Hybrid electrical power source for thrust vector control electromechanical actuation
- NASA, Huntsville, AL (United States). Marshall Space Flight Center
- Auburn Univ., AL (United States). Space Power Inst.
The next generation of launch vehicles propose to use electromechanical actuators (EMA`s) for engine gimbaling and aerosurface control to eliminate hydraulics and its associated systems and problems. The new actuation systems are not without their own challenges. An EMA`s duty cycle has two components: a high power pulse to initiate and perform the actuation, and a nominal load to maintain position. Conventional batteries must be sized to meet the pulse power requirement while maintaining a bus voltage in range to satisfy the needs of the EMA control electronics, and therein lies the problem. Restricting the voltage sag limits the discharge rate of the battery and therefore requires an increase in the Amp-hour rating, which relates directly to an increase in weight. An option to lower power source weight is a hybrid source consisting of a conventional battery and a capacitor bank. A hybrid source of this type would utilize the power density strengths of a capacitor bank to meet the high power pulse demands, and the energy density strengths of a battery to provide average power and capacitor recharging. Testing has been performed at NASA`s Marshall Space Flight Center (MSFC) with support from Auburn University`s Space Power Institute to investigate the validity of the hybrid power source concept. This proof-of-concept testing used chemical double layer (CDL) capacitor technology in the form of a {approx}5 farad-270 volt capacitor bank, standard deep cycle marine lead-acid batteries, and a 25 horse power EMA developed at MSFC. The test data was used to size a flight type Ag-Zn battery to perform the same task in a battery-only configuration, and also size a battery for a hybrid configuration. Test results and analysis show that a >50% weight savings can be realized with this type of hybrid power source with no negative effect on performance. These results support the need for further development in the area of CDL capacitors and hybrid configurations.
- OSTI ID:
- 163385
- Report Number(s):
- CONF-950729-; TRN: IM9604%%490
- Resource Relation:
- Conference: 30. intersociety energy conversion engineering conference, Orlando, FL (United States), 30 Jul - 5 Aug 1995; Other Information: PBD: 1995; Related Information: Is Part Of Proceedings of the 30. intersociety energy conversion engineering conference. Volume 1; Goswami, D.Y. [ed.] [Univ. of Florida, Gainesville, FL (United States)]; Kannberg, L.D.; Somasundaram, S. [eds.] [Pacific Northwest Lab., Richland, WA (United States)]; Mancini, T.R. [ed.] [Sandia National Labs., Albuquerque, NM (United States)]; PB: 798 p.
- Country of Publication:
- United States
- Language:
- English
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