Due to a UAV's compact and sensitive platform, there is no room for a bulky synchronous generator that allows a fixed voltage output. Likewise, the opportunity for a fixed speed engine to feed the UAV's permanent magnet generator to create a constant voltage output does not exist. A GCU (Generator Control Unit) functions as a mediator between the variable voltage and frequency alternator/generator and the stabilized DC bus requirement set by the payload. Its non-isolated topology provides high efficiency, light weight and a small form factor which makes the GCU power supply very attractive for systems that are powered by Permanent Magnet Generators (PMG) such as light weight UAVs, avionics, electronic warfare and other military applications.
A variety of products for this type of application are available. Some accept the three-phase output of the PMG directly, while others require a bridge rectifier on the front end. A rugged AC/DC GCU product qualified to key test methods per MIL-STD-810 and MIL-STD-461 is critical. Input voltage may range widely from 32VAC to 150VAC while the output voltage must always remain well within the MIL-STD-704 voltage limits, for the various airborne loads on the platform. These basic configurations will meet a wide range of UAS application requirements and ensure the platform integrator offers ample power available on the power bus. Current is "automatically" shared between the units by a voltage slope, slightly decreasing output voltage with load current rise. True N+1 redundancy can be achieved by connecting all the outputs through rectifiers. Recognizing the need for application specific solutions, Milpower offers several specialized types of GCUs, some are based on COTS "building blocks" and others are customized to the application specification.
The M7049 accepts a wide range of DC input voltage, variable from 30 to 200VDC input voltage range, compatible with the rectified output of most PMG’s.(Since this unit is DC fed, it requires a front-end bridge rectifier when used as a PMG GCU). The M7049 can deliver up to 750W continuous (900W peak/30 sec. over-load capability), making it perfect for feeding COTS and MIL-STD compliant payloads.
