Custom Power Solution Designed for the Toughest Environments

May 30, 2014

Defense applications can provide some of the toughest challenges for power system designers. Not only are these systems often complex and challenging electrically, but the harsh environments in which they must operate demand a robust and rugged design. Often it is handling by the end users that cause the roughest treatment, with the “loose cargo” requirement providing one of the most demanding tests. To meet this requirement, systems must be able to withstand being thrown into the back of an armored vehicle and be driven across rough ground for a day whilst bouncing around in the back with no restraints to hold it down.

To help them develop systems that meet both the electrical and mechanical requirements, customers often turn to Vicor Custom Power. One recent project that needed to meet the loose cargo requirement was a ruggedized portable test set to troubleshoot a wide range of systems such as radios, computers and navigation systems for a military customer.

This design had unique requirements, calling for two complete power supplies for a VXI backplane that would be used to power oscilloscopes, spectrum analyzers, and other instrumentation in the rack. In addition 10 fully programmable power supplies were required for test purposes, nine of which provided 0-40 V 0-5 A and a tenth higher voltage power supply with an output of 60 V. All power supplies had fully isolated outputs and a polarity reversing switch. In addition, the power supplies could be connected directly in series or parallel. In total the system needed 24 outputs in a standard VXI Chassis configuration.

Freedom Power, the Vicor Custom Power company that delivered the project, was able to quickly develop a solution, even though the large number of outputs meant that over 50 Vicor converters and Filter Input Attenuator Modules (FIAMs) were utilized to provide the output voltages, EMI filtering, transient protection, and inrush current limiting. In addition, 13 microcontrollers were used to run programmable outputs plus interfacing to connect to computers and to the VXI.

The programmable supplies needed a relatively low noise of 80 mV. In order to get the efficiency and to make it manageable for the project, Freedom Power customized the supply by installing a high performance linear regulator on the output of each Vicor module. With a minimum 2 V drop across the regulator, the outputs of the Vicor modules are set to be correspondingly 2 V higher to maximize efficiency. Precision control of the output voltage & current limit was achieved with a microcontroller to manage the Vicor supplies.

Although the Vicor modules are inherently rugged due to their design and encapsulation, to meet the requirements, which is equivalent to 8 hours endurance as loose cargo, rough road, 45 miles per hour unrestrained transportation, the project also used six heavy duty shock mounts on top and bottom of the test set and four wire rope (chain) shock mounts.

As Jim Russell, President, Freedom Power Systems said, “Usually the easiest part of the job is the volts in and volts out – Freedom Power simply buys a Vicor module and we are done. The expertise that Freedom Power brings is in the rugged, high density, customized COTS design, which is our core skill. The two decades of experience in this field has earned us a trusted reputation and enabled us to assemble a “library” of successful designs to draw on for future challenging projects. We tend to handle the projects that are either too tough for the customer, or where the customer doesn’t have the range of specialized internal resources needed to succeed in this area.”

To find out more about Vicor Custom Power, or to discuss your unique requirements with a member of the team, visit our web site.  You can also find out more about Freedom Power Systems.

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