Research project status
As you maybe remember, in the end of last I started a project at the Helsinki
University of Technology, High voltage Laboratory, that included design and
construction of a middle-sized TC. The work will constitute my licensiate
and, if enough relevant, my PhD thesis in the near future.
Maybe some of you are interested in what is the status of that project.
The TC to be buiild will have following (still temptative) characteristics:
- secondary 1.5 m tall
- toroid at leat 1 m diameter
- primary capacitor 0.1 uF
- primary max. voltage 20 kV DC (not AC)
- top pulse rate 800 Hz
- estimated power requirement 16 kW
- rotary spark gap
- possibility to precisely control capacitor charging voltage and pulse rate
The quest quickly moved from TC engineering problems to DC power supply design
issues. It was realized that a 16 kW, 20 kV DC power supply (with stable but
variable output voltage) was not easily built with a simple distribution
After extensive literature examination, it was decided to employ a switching
power supply. The initial power supply design therefore turned into a Capacitor
Charging Power Supply (CCPS) design.
The topology chosen is a "full bridge, series load resonant CCPS", working at a
resonant frequency of 50 kHz: the project is modular, as it features 4 modules
each capable of outputting 5 kV at 5 kW. Each module has got its own power
drivers (IGBTs) and its own ferrite-cored transformer. Control unit is
all 4 modules: it is a Unitrode resonant power supply control chip.
As you maybe guess, controller, driver and transformer have to be designed and
built by myself. The transformer(s) use two ferrite U-cores from Philips for a
total core outer size of about 10 x 10 cm.
I am currently assembling the controller and one driver. In a couple of weeks I
should receive the U-cores, bobbins, mylar tape and remaining components. I
then be able to test a single module.
The advantage of this design is that it can be accomplished will off-the-self
and relatively inexpensive components. The disadvantage is that I would have
liked more the design to be scalable in terms of current, not of voltage. But
that would have meant more engineering problems in the transformer and use of
expensive esotheric components.
I will provide all plans and schematics of the whole CCPS as soon as I will get
it up and running.
In the mean time I need your suggestions to find a NAME for my project (yes, as
stupid as it sounds, this is still an unsolved "design issue"). It is
built two TC, named Adam and Eve. Adam will be built first and will use this
precise CCPS power supply. Eve will feature a more simple RSG and a usual AC
distribution transformer. Adam will be for research and measurment, Eve
shows and demonstrations.
But what about a suitable name for the whole project? Just one word, name or
acronym would be enough, possibly english. If you have some good ideas, please
email my privately.