Boeing is one of several manufacturers authorized by the FCC to design, build, and launch LEO and MEO satellites into orbit. Boeing's O3b project aims to provide broadband connectivity to the "other 3 billion people" (O3b) whose access to high-speed internet is limited or nonexistent. A major challenge in designing LEO satellites like O3b is supplying the power required by the advanced communication circuitry without increasing the size or weight of the power grid. To further complicate matters, the power solution must be flexible and scalable to accommodate potential unforeseen design changes or modifications in future versions. The accelerated deployment plan also demands a rapid time to market to meet the project deadlines.
Surviving in Space:
Space is a hostile and unforgiving environment, especially for electrical components, due to factors such as enormous temperature variations, vibration, and radiation exposure. However, the required level of radiation protection depends on the satellite's orbit. Satellites in the highest geostationary orbits (GEO) require radiation-resistant devices because they are outside the Van Allen belts and therefore exposed to higher levels of radiation. The expected operational lifespan of GEO satellites is three to four times longer than that of other satellites, further increasing their radiation exposure. MEO and LEO satellites occupy much lower orbits within the Van Allen belts, so their radiation exposure is lower, and it is sufficient for their components to be able to withstand it. Some might argue that conventional products are suitable for use on LEO satellites, but this would be very risky even with the lower radiation levels. Prudence dictates that a certain level of radiation protection be in place to ensure the satellite's proper functioning. After all, it's impossible to send a maintenance technician to fix a malfunction if a conventional $0.25 component fails in space and takes a multi-million dollar satellite out of service.
A radiation-tolerant solution with high power density
An alternative to conventional power solutions is to use a modular and radiation-tolerant power supply solution that also offers protection against radiation and continues to provide the highest power density on the market along with enormous flexibility and scalability of its architecture and implementation (Figure 1).
Figure 1: Vicor module and power supply network demonstrating its easy implementation.
The close collaboration between Vicor and Boeing on the O3b program has led to the development of a high-performance solution. Vicor's radiation- and fault-tolerant DC/DC converter power modules, supplied in Vicor's new metallized SM-ChiP™ package, can power low-voltage ASICs up to 300 W from a 100 V nominal supply. Their immunity to single-event failures is achieved through the redundant architecture of each module, which integrates two identical power units in parallel with fault-tolerant control ICs in a single high-density SM-ChiP package (Figure 2).
Figure 2: Design of a dual fault-tolerant power unit.
Advanced communications satellites require high power density and low noise. Vicor's high-frequency, soft-switching ZCS/ZVS (zero current/voltage switching) power stages reduce overall power system noise and filtering requirements, thereby ensuring the high level of signal integrity and system reliability demanded.
The complete point-of-load power solution consists of four SM-Chip: the BCM3423, a bus converter rated at 100V, 300W, and K = 1/3 in a 34 x 23mm package; the PRM2919, a regulator rated at 33V and 200W in a 29 x 19mm package; and two VTM2919 current multipliers with K = 1/32 and an output of 0.8V at 150A and
K = 1/8 with an output of 3.3V at 50A. This solution powers the ASIC directly from the 100V supply with a minimal number of external components and operates with low noise.
All modules are supplied in Vicor's high-density SM-ChiP package with BGA (ball grid array) connections. The operating temperature of the ChiPs is -30 to 125°C.
The innovation needed for the new space market:
There are some important differences between discrete and modular power solutions. To meet the ambitious O3b targets, a modular solution excels in several key areas. For more information on the conclusions presented in the table, please read this document.
Vicor and BCM® are registered trademarks of Vicor Corporation; SM-ChiP™, PRM™, and VTM™ are trademarks of Vicor Corporation. All other trademarks are the property of their respective owners.
