UWE Bristol Engineering showcase 2015

Ben Daffurn
BEng – Electronic Engineering
Project Supervisor
Nigel Gunton
Voltage Spike Generator for Qualification Testing
Background:
Modern aircraft systems contain many pieces of complex electronic
equipment; vital aircraft systems that would originally have been mechanical
have been replaced with electrical alternatives . Voltage spikes have always
been present in the electrical systems on aircraft; however this huge increase
in complex integrated electronic equipment has meant that the need to
provide protection against them is now more critical.
To ensure a high standard of safety, a number of aviation authorities exist to
ensure that international best practices are followed; the Federal Aviation
Authority (FAA) and Civil Aviation Authority (CAA) are two such authorities.
Before an item of electronic equipment is allowed to operate as part of an
aircraft in flight, compliance must be shown to the rules and regulations set
out by the FAA or CAA. There are a number of aviation standards/
specifications available that can be followed to demonstrate this compliance.
A Voltage Spike:
A Voltage Spike is a short duration high voltage pulse and is most commonly
caused by electric motors. Spikes can be several hundred volts in amplitude
and generally only last for a few microseconds.
For qualification test purposes the characteristics of the voltage spike are
defined by industry standards, typically DO-160G for civil and MIL-STD-461F
for military platforms. A typical voltage spike can be seen above.
Research:
The background research that was conducted into voltage spike generator
looked into; the common causes of voltage spikes in aircraft electrical
systems , the effects of voltage spikes and methods of voltage spike
generation. Additionally detailed research was conducted into the
qualification test standards DO-160G and MIL-STD-461F. These commonly
used standards were used to derive the requirements fort he voltage spike
generator.
The Design:
The block diagram above shows the top level system design for the voltage
spike generator. The fundamental components include a resonant circuit to
define the characteristic of the spike, a low pass filter to provide the
required source impedance and a microcontroller circuit to provide timing
functionality / a user interface.
Prototype:
A prototype is currently being developed as proof of concept of the design.
Project summary
This project details the design and
development of a voltage spike generator that
complies with the applicable aviation
standards.
Project Objectives
The aim of the project was to design and
develop a voltage spike generator that is
capable of safely and reliably generating and
applying a voltage spike to the Equipment
Under Test (EUT). This included:
• Compliance to the applicable aviation
standards, primarily DO-160G.
• Verification of the design.
• Accompanying documentation ,including a
user manual, to enable calibration,
electrical safety checks and release of the
Test Equipment (TE) before use.
Project Conclusion
As a whole, the project was a success. Despite
not all of the project objectives being met in
the available time frame, extensive simulation
and analysis has provided confidence that the
design will safely and reliably generate
voltage spikes, that comply with the
applicable aviation standards.