Power supply design for avionics has become an area of increased activity over the past few years.
New to the market are industrial-quality, high-current, lithium-based battery systems. Available from a variety of vendors, these batteries are characterised by their low weight and high energy availability.
In avionics and terrestrial mobile applications, every pound saved counts. Typical older equipment provided portable power with 
heavy lead acid battery systems.
Redesigning older lead acid battery systems can reduce weight by 50% or more without sacrificing stored energy performance.
Couple low-mass lithium batteries with reduced-weight electronics design and a modern battery power supply can vastly improve the available energy to weight ratio of the entire power system.
Efficiency improvements
Power supply 
efficiency improvements can be achieved through careful selection of the power supply topology for the required application.
Good power supply design can achieve 90% core efficiency. This high-frequency forward converter design was optimised for a particular voltage current load curve.
Core efficiency refers to the actual switcher design efficiency prior to application of additional features. Supervisory features such as over and under voltage lockout, current fold-back, over voltage detection, redundant controls, and power factor correction can rapidly eat away at a power supply’s core efficiency number.
Power supply reliability and proven mean time between failures (MTBF) – in short, design quality –
is of paramount importance in avionics.
Power supply reliability can be greatly increased through conservative design techniques. This requires design discipline.
A high reliability power supply design is one in which every component part has been analysed.
A component’s normal operating range, de-rating curves, altitude effects, and known useful life characteristics must be considered by the conservative designer. Experience counts when making component selection. Often a thankless task, part selection is easily 75% of the challenge in high-reliability design.
Balancing circuit board physical area constraints, de-rating requirements and component cost is a delicate art. The best designs are achieved when component selection is not rushed.
Power supply hot swap and load sharing features have become extremely popular. The ability to swap one power module for another results in greatly reduced overall system mean time to repair. (MTTR) When aircraft service or terrestrial vehicle service must be performed quickly, low MTTR power supply sub-assembly designs really help.
Use of low-cost edge finger contacts, modular sub-system design, and the ability for sub-systems to load share makes hot swap possible.
Diode FET output stages can perform load sharing with great efficiency, low cost, low weight and low heat. Microcontroller supervision can add a layer of system-level monitoring of power supply health.
Power systems based on Intelligent Platform Management Interface (IPMI) provide an industry-standard method of performing power management. Alternately, custom communications can be implemented to supervise power management.
Author is Paul Nickelsberg, president at Orchid Technologies