Industry : Electronics

Category : Software Development

The Challenge:

To develop a fully-featured, flexible, and reliable test system to determine the mean-time-between-failure (MTBF) of a multi-output power supply unit (PSU) with three outputs- low-voltage DC, high-voltage DC and single phase AC power

The Technology:

Hardware : Compact PCI/PXI, Compact FieldPoint, NI PXI-6534 High Speed Digital Pattern I/O Card,
PXI-6534, NI PXI-6070E- High-speed Data Acquisition Card, Switching MOSFETS, PXI-6508 Digital I/O card.
Software  : LabVIEW RT

The Solution :

The system was designed to allow the outputs to be subjected to a loading pattern that simulated the stresses experienced during a typical loading cycle, while reducing the duration to shorten the overall testing time. A set of critical parameters were calculated from the waveforms for each cycle and recorded. At the end of the test, the results from all of the units tested were consolidated and the MTBF calculated

The software architecture was designed to judiciously spread the tasks that do not occur each cycle , over multiple cycles and utilize the cooling-off periods. For each PSU a separate loop was launched to enable independent monitoring and control, thus helping the user to observe the status of any PSU at a given point of time

Engineering Challenges:

• Data processing -To process 4.8 mbps of data acquired by 24 channels at the rate of 100 KS/s in real time, store the computed parameters for each cycle, the entire cycle’s waveform to the disk when any irregularities are detected
• Hot swapping – Allow the hot swapping of failed units without stopping the other units under test
• Scalability - Design a highly scalable architecture that allows the testing of other models
• Safety checks – Monitor the temperatures and safety parameters at various locations and initiate safety actions

Value Addition:

• Reliability - The system was highly reliable thus ensuring 24*7 operation without any interruption
• Precise simulation - The load circuit was designed in a manner to help simulate the loading patterns precisely
• Flexibility - The status of any PSU could be observed at a given point of time Fig 1. shows the details for a single PSU

Commendation:

The application was one of the finalists under the R&D/ Lab automation category for the NI 2004 Best Application Contest
http://sine.ni.com/cs/app/doc/p/id/cs-528