LIST OF PROFESSIONAL ACCOMPLISHMENTS
Neil J. Barabas
1982: Developed/Discovered that RHP pole in control function
of a continuous conduction flyback converter could be
avoided by using a separate winding for feedback
regulation. The ESR of the output capacitors has the
effect of providing a feedback term similar to that
provided by current mode control. The outcome was that
an efficient in size and power, 450 W flyback with +-
85V outputs could be realized.
1983: Invented a method of feedback control using current
mode to provide high power factor from single phase AC
without complicated circuitry. This resulted in a
landmark product for Rantec Div. of Emerson Electric.
Subsequently patented.
1984: Designed a tri-service military qualified offline power
supply using a constant volt-second forward converter
front end with magamp regulated outputs. This gave
excellent line and load regulation with simple
isolation requirements.
1985: Performed pioneering work on an optimized switching
element consisting of a high voltage bipolar emitter
switched by a low voltage mosfet, with a current
feedback transformer to provide base drive. Also
combined a low voltage mosfet with a TL431 shunt
regulator to make an extremely low drop-out and simple
linear post regulator. These items were helpful in
reducing costs in high volume commercial manufacturing.
1986: Research into a push-pull topology without an output
inductor resulted in several innovative products. The
initial products were some of the first DC-DC
converters in the aftermarket car stereo industry to
use power mosfets. By using lowered gate voltage,
current limiting under startup conditions could be
realized. This is now an industry standard topology.
1987: Continued development of the push-pull inductorless
topology resulted in high efficiency converters for
both Litton Systems and the Ballistic Missile Defense
Initiative at Lawrence Livermore Labs. The push-pull
converter without an inductor operates in quasi-
resonant mode. It also has excellent cross regulation
for multiple output voltages. Combined with a boost
front end, it can regulate over a wide range of input
voltages. At Litton, this was successfully used in a
miniature power converter and motor driver that was
used in the guidance system of an advanced missile
produced by Boeing.
1988: The Livermore work resulted in a 5 output (5V@15A plus
+-12,-5,+24), isolated, 5-20V input converter than
achieved 82% efficiency at low line input and weighed
180 grams (both of these were the prime criteria for
this space based program). By improving the system
power specifications, and selecting an optimum battery
technology, I was able to further reduce the power
system weight by a factor of three.
1989: Used IGBT's to make an extremely small capacitor
charger to power a miniature flash lamp pumped high
power laser. This topology was successfully used in a
laser rangefinder on the Clementine spacecraft to
measure the moon.
1990: Combined emitter switched bipolars with high power
factor current mode control to design a unique, wide
range supply to power the flash lamp of a very high
power laser for industrial and medical work. This
development allowed a considerable reduction in the
size of the cabinet housing the controls for the laser.
1991: Replaced a large 60 Hz unregulated supply with a
quasiresonant full bridge phase shift converter. This
allowed high peak power with a regulated output even
though the input 115V sagged considerably. (Up to 4kW
DC was output for up to several hundred msec) An
innovative circuit modeled the power fet heating under
these transients. This design allowed a power machine
controller to meet its size and weight requirements.
1992: Designed an ultra high reliability, radiation tolerant
multi-output DC-DC convert for the NASA/JPL Cassini
mission, began orbiting Saturn in 2004.
1993: Invented a method of current sense for a motor drive
that simplified the circuitry and allowed use of
average current mode control in motor drives. Motor
drives I designed are used in all the Haas Automation
robotic machine tools.
1994: JPL research resulted in a very high efficiency
converter using synchronous rectifiers and matrix
transformers for a next generation solid state
transmitter. Also characterized and completed
modeling a hybrid MCT/FET switch. Finally, completed
initial design work on ultra low power, low temp
converters for the future Mars Microlander.
1995: Designed a simple circuit to use current mode control
in a boost regulator that is now reaching high volume
production as a voltage stabilizer for mobile power
systems.
1996: Precedent setting wide bandwidth, high current voltage
source designed for VLSI test applications. Average
current, multi-loop feedback and innovative parallelism
adapted to solve risetime problems. 100W per cubic
inch switching tracking DC-DC converter also used to
improve efficiency.
1997: Introduced average current mode control to mobile audio
applications. Major benefit of good regulation at
light to no loads creates audiophile sound in a mobile
environment. Optically isolated, glitch free shutdown
also reduced to practice.
1998: Multi-phase high speed switcher with leading edge modulation
developed as a possible replacement for a MegaHertz bandwidth
linear power supply
1999: Worked with a high-end audio designer, Bob Carver, to improve the
switching tracking converter in his products.
2000: Designed battery controller board for the Mars Exploration Rovers
(Spirit and Opportunity). Proprietary bus for control and reporting.
Autonomous operation, including cell charge balancing. Multiple
reset/recovery routines led to saving the mission after a software
error in the main computer caused loss of communications with
Earth.
2001: Multi-loop fuel cell bi-directional converter control was developed
that allowed smooth and continuous control of many variables:
charge and discharge current, bus source and sink current, fuel
cell voltage limits, and bus voltage control.
2002: 200W per cubic inch 16V converter with proprietary techniques was
designed and PCB laid out.
2003: 50kW modular constant current converter, no optos or electrolytics
results in extremely long lifetime with high MTBF. Both aggressive
initial and lifecycle cost goals were met (~$0.06 per watt)
2004: JIMO- Jupiter Icy Moons Orbiter for JPL and NASA. Nuclear reactor
is to be used to spin Brayton cycle alternators, with power ratings of
~60kW each. Design of rectifier starter, and bi-directional battery
and solar cell interface converters. Extremely high radiation
environment, with 20 year design life. Planar magnetic design.
2005: Designed very high density, sequenced, high temperature and high
reliability power supplies for solid state microwave amplifiers.
2006: Developed a very low cost 1kW Power Factor Control input supply for
home audio applications.
Design a solid state pyro firing card for the JPL Mars Science Lab Rover.
2007: Invented and patented a circuit for a high efficiency, high Power Factor,
Universal input offline constant current miniature LED supply.
2008: Auxiliary power supply for electric car: 320 VDC nominal input, isolated
13.5 VDC at 200A output. Smaller than 100A version, 97% efficiency,
no heatsink required.
2009: Multi-output 20kV, 2kW power supply for Traveling Wave Tube microwave
amplifier. Developed low-cost method of building high voltage transformers
without potting yet that are still compact. Ten nanosecond switch for 1kV
focus electrode control
2010: Sixty Hertz transformer/rectifier replacement converter. Extremely low parts
count. Zero voltage switching, proprietary start technique. Auxiliary converter
(for keep-alive to use remote control) idle power ~300mW.
2011: Invented innovative Current to Current Converter (patent pending) for using LED
lighting with existing fixtures.