Modular Power - November 05th, 2016

Modular Distributed Power Payload Architectures

For Optimisation of Performance, Efficiency, Size, Weight, Power and Cost (SWaP-C)

Introduction
In today’s commercial avionics, Defence Airborne and Land electronics the need for higher performance while decreasing Size, Weight and Power, Cost (SWaP-C) is gathering momentum. The power supply is a key determining factor in the final system size, weight, and thermal design. ELEK-TECH Electronic Systems will discuss methods for satisfying your system’s power requirements with efficient, cost-effective power design.

The Modular Power Architecture is Critical for Efficient Design and Optimisation
One way that ELEK-TECH Electronic Systems customers can decrease the power footprint is to move to our modular distributed power architecture, which comprises of our small form factor Electronic Payload Modules. Our PSU EPM’s can be controlled digitally and have in built BIT for diagnostics, all controlled by our Integrated System Controller (ISC). The system controller is responsible for the power control and monitoring of all modules fitted with in the chassis and can be accessed through our Intelligent Diagnostics Platform Interface (IDPI).
 
Instead of having several isolated supplies to drive the internal loads, our distributed architecture has one isolated converter and multiple, smaller, dense point of load (POL) converters. POL converters offer the advantages of smaller size, higher efficiency, and better performance than the isolated power converter method.
 
Many Defence avionic systems have a power source that is governed by MIL-STD-704. MIL-STD-704 highlights the power source limits for various conditions that include both transient and steady state limits. For example, MIL-STD-704 Rev F has transient limits for 28V DC systems to be between 18V and 50V.
 
Many applications in the Defence avionics systems are required to meet older revisions of MIL-STD-704 which can contain even more severe transients between 16V and 80V. These large input ranges, coupled with many systems having an isolation requirement, make some type of isolation stage between the source and load required. ELEK-TECH ELECTRONIC SYSTEMS work very closely with GAIA Converters UK who supply high power density COTs Power modules, these are what we normal place at the front end of our system. Has they are fully compliant to MIL-STD-704 transients and abnormal voltages it minimises the risk at the subsystem level.
 
Today’s high performance digital systems also require ultra-tight regulation on the output voltage to prevent damage. We accomplish this by locating dense POLs very close to the load this could be an FPGA, Processor or fast sampling ADC\DAC. This decreases the load variation by eliminating the need for long copper traces on a circuit board and because of their small size and light weight, it’s possible to mount POLs very close to the load, which saves space by eliminating the potential requirements for large heatsinks or mechanical reinforcing structures.
 
Another very useful function to look for is the ability of a POL to control the timing and ramp rate of rise and fall of the output voltage. This is often done by accessing the “Track” pin on the desired POL.
 
The track pin allows us to control the rate of rise of the output voltage by placing an external signal at the track pin. The use of the track pin, is extremely useful if multiple voltages are supplying the same part and negates race conditions of supplies for example FPGA Core & I/O. The track pin is flexible and can be configured to suit your system.

If our customers’ specific needs are to reduce the load transient performance, adding a bulk capacitance to the output pins is possible. This capacitance can decrease output voltage variations from very fast load current changes.
 
Finally, should we want to decrease the input current ripple, a bulk capacitor can be added to the input of the POL. There is no upper limit to the amount of capacitance that can be added to the input of the POL. The only limit you’ll need to account for is if the POL is driven from another DC-DC converter. If so, then this part could have a requirement for the maximum amount of output capacitance.

Modular Power Payload Architectures for Next Generation Electronic Systems.
 
With the new variety of Modular Power Payload Modules, today’s commercial avionics, Defence Airborne and Land systems our customers have smarter, newer options in designing high performance systems that meet evolving light weight, high performance, and low cost system requirements.