Packaging the Space Power Supply

Space Power Supplies can be fabricated with all discrete piece parts, fully in hybrid microcircuit form or a mixture of both. A full hybrid approach is more expensive and takes longer to develop. An all discrete design will be non-competitive for all but high power designs. The part hybrid, part discrete construction is best for most applications, and combines one or more hybrid DC/DC Converter modules in a housing with other discrete circuitry.

Discrete construction also encompasses surface mount piece parts and techniques. In this mixed construction, the principal building block circuits are contained within the hybrid. The higher power and bulkier discrete components are packaged separately. This gives the part hybrid, part discrete construction good volumetric efficiency and allows better thermal paths for the higher power dissipators.

In addition, the part hybrid, part discrete construction allows mechanical provisions for EMI filtering, such as EMI plenums, making EMI filtering easier to implement than in full hybrids.

The enclosure method of choice for current generation space power supplies is the NC milled aluminum chassis. This offers many benefits, such as minimal weight, structural strength, good thermal paths, opportunities for radiation shielding and excellent EMI performance. This chassis may be Nickel plated for corrosion resistance.

In wiring the space power supply, wire insulation resistant to vibration damage should be used. When in space, vibration effects are negligible. However, large numbers or thermal cycles can occur. Therefore, the design of the wiring must be such that connections do not fail due to thermal cycle induced damage. In wiring to DC/DC converter modules, it is always best to use a compliant lead wire, rather than soldering a pin directly to a printed wiring board.