DIY Turbopump Controller

Nicolas Krause · Post by **Nicolas Krause** » Thu Jan 14, 2021 1:39 pm

While I've purchased a TPM 50 turbopump for 100$ off of eBay, the device did not come with a controller. I'm unable to afford the purchase price of a new turbotronik controller, and while I've been looking on eBay, I haven't seen one come up for a price I can afford. I have a portion of the circuit completed in KiCad and I'm at the point where I have to start designing to power supply for the whole shebang. I'll need three different power levels, a 3.3V for the microcontroller and LCD screen, 15V for the driver chip (a FAN7388) and then 200V for the IGBT's that make up the driver circuit for the motor itself. I've been looking at the specs of the TurboTronik controller and it states that on startup it'll draw a maximum of 45W of power or 64VA. Given that it also specs that the voltage for each phase of the motor is 150V I've calculated the max current as 64VA/(1.73*150V)=246mA. So with a bit of a safety buffer a 200V supply that can also give up to 300mA of current should be alright no? This is the first time I'm designing an electronics project with this many moving parts and I just want to confirm I'm getting the basics right as I go forward.

John Futter · Post by **John Futter** » Thu Jan 14, 2021 1:59 pm

Nicolas
Look up my previous posts on this
I've built around 20 controllers for these. I used a simple 35-0-35 volt transformer to give me relay selected voltage of 45 volts and 90 volts to run the pump.
i switched supplies at approx half freq

Nicolas Krause · Post by **Nicolas Krause** » Thu Jan 14, 2021 2:23 pm

Thanks for the reply John, I've found your design on the coulter smithing forums. Just to confirm a couple of things I'm reading about the device.

There's no magnet sensor on the TPM 50
Your design uses no microcontroller, but there is some digital logic, it looks like there's an output I assume to a computer down the line?
If I run the pump at 90V will I get full RPMs? Or is the 150V the manufacturer specced just a standard engineering safety margin?

John Futter · Post by **John Futter** » Sat Jan 16, 2021 9:03 pm

Nicolas
The NT10 /NT13 controllers that were used we these devices used pwm and turned the pwm on / off so you heard a zip zip noise from the motor.
they used the on / off so they could use the higher voltage and still keep the motor windings cool.
My design did use a micro to generate the main freq to the 3phase logic generator and driver so micro did only monitor motor current and based on current it incremented the frequency when the motor current was below two amps. Net effect was the unit would accelerate to full noise in about 3 minutes in a leak free system.
Sorry did not include the micro stuff as it was proprietry to work ( some one elses work)

Nicolas Krause · Post by **Nicolas Krause** » Sat Jan 16, 2021 10:11 pm

I'd read that it was proprietary work on the original thread, no worries there, looks like a fun project for me to add a microcontroller. Besides, I've got a lot more faith in your circuit design skills than mine when it comes to the driver portion! I'm in the process of replicating your circuit at the moment in KiCad, I'll probably figure out all the components and circuit operation and then work on adding some firmware to control the whole thing.

John Futter · Post by **John Futter** » Sun Jan 17, 2021 12:44 pm

i'll post some more when I get to work
I havent been there since 22/12/20 big holiday wiring up my new house

Nicolas Krause · Post by **Nicolas Krause** » Fri Jan 22, 2021 2:03 pm

Hi John,

I've got a first draft of your schematic done up in KiCad, still have to build a bunch of footprints and possibly swap out a component or two, but lot of the basic work is done. I've also ordered a couple of the new Raspberry Pi Pico microcontrollers. They're very cheap, 4$, and seem to meet all the specs for what I need to do. So the next steps are to figure out the connections between the Pico and the pump controller circuit and then I can move on to layout once I've got a final version of the schematic.

Peter Schmelcher · Post by **Peter Schmelcher** » Sat Jan 23, 2021 4:19 pm

Nicolas these are internal pics of my NT10 controller circuit board before I repaired it but after cleaning with compressed air. It had previously been repaired by someone and was sold "as is". Unfortunately, I never found any schematics so I repaired it using these pics.

The NT10 controller spins up the turbo in discrete drive frequency steps with coasting between frequency increases. During the coasting moments the voltage produced by the motor windings are measured and used as a tachometer reading. As I recall the turbo needs to spin up within 2 minutes getting quickly through a 50Krpm mechanical rotor resonance.

Today my plan B repair would be a new variable frequency drive for a CNC router spindle ($130). The faster VFDs run up to 1000 Hz and I suspect that with a crystal change hack one could increase the upper frequency.
-Peter

Nikodem Czechowski · Post by **Nikodem Czechowski** » Sat Jan 23, 2021 6:31 pm

Nicolas Krause wrote: ↑Fri Jan 22, 2021 2:03 pm Hi John,

I've got a first draft of your schematic done up in KiCad, still have to build a bunch of footprints and possibly swap out a component or two, but lot of the basic work is done. I've also ordered a couple of the new Raspberry Pi Pico microcontrollers. They're very cheap, 4$, and seem to meet all the specs for what I need to do. So the next steps are to figure out the connections between the Pico and the pump controller circuit and then I can move on to layout once I've got a final version of the schematic.

Capture.PNG

Can you share the schematics in KiCad? Would love to join the work, I can (help) design the PCB, if you would like. Especially that I am looking for a controller for my Turbovac 50

Nicolas Krause · Post by **Nicolas Krause** » Sat Jan 23, 2021 8:16 pm

Peter, thank you for photos and explanation of how the device measures the turbopump speed. I think at this point I'll press on with the custom design rather than the VFD option given the work John has already put into the circuit design.

Nikodem, I'm happy to share the schematic, I should warn you that it's missing some details and I swapped in some components I was missing in the library rather than build them out. It's a first draft, and I still have to put in connections for the microcontroller, LCD screen, on/off switch etc... As far as helping with the PCB design, I appreciate the offer but I like the work and I need the practice!

Nikodem Czechowski · Post by **Nikodem Czechowski** » Sun Jan 24, 2021 5:02 am

OK Nicolas

If you would need any assistance with PCB and electronics, feel free to ask.

Jerry Biehler · Post by **Jerry Biehler** » Sun Jan 24, 2021 5:49 am

I have an official schematic for the controller for these pumps. https://drive.google.com/file/d/0B1bUBQ ... sp=sharing

There are about 4 drive models that will run this pump, the NT10, NT12, and NT13 as well as the NT50 which I have provided the schematic for. Sometimes these models do pop on ebay at reasonable prices. I also may know someone with working NT50s for sale. I think there is a NT11 but I have never seen one.

Nikodem Czechowski · Post by **Nikodem Czechowski** » Sun Jan 24, 2021 7:49 am

Jerry Biehler wrote: ↑Sun Jan 24, 2021 5:49 am I have an official schematic for the controller for these pumps. https://drive.google.com/file/d/0B1bUBQ ... sp=sharing

There are about 4 drive models that will run this pump, the NT10, NT12, and NT13 as well as the NT50 which I have provided the schematic for. Sometimes these models do pop on ebay at reasonable prices. I also may know someone with working NT50s for sale. I think there is a NT11 but I have never seen one.

NT50 seems to be overly complicated and based on discrete ICs and logic - a thing, that easily can fit into an Arduino module. I would not recomend replicating it nowadays. Maybe the driver stage, of the transistors are still available.

Also - what is a reasonable price for this controllers?

Post by **Richard Hull** » Sun Jan 24, 2021 10:36 am

Nikodem, please do not include quotes from the same thread. We are following it just fine. We have to tell this to many people who come here. I realize they are the norm on many sites. However, we are capable of fully and properly following a single post thread through all of its reply postings. Just simply reply without quoting something that is either immediately above or even 5 posts back in the thread, we will know what you are talking about in reply.

Richard Hull

Nicolas Krause · Post by **Nicolas Krause** » Sun Jan 24, 2021 1:40 pm

Thank you Jerry, that's sure to prove useful! As far as prices for a controller on eBay, my pump was 100$ w/out a controller, I routinely see Turbotroniks listed for over $1000, and unfortunately haven't had any look looking for cheap ones.

Rex Allers · Post by **Rex Allers** » Mon Jan 25, 2021 7:24 am

Jerry,
I guess you posted the scans of the NT50 controller a few years back as I have a saved copy. (Not sure if the post was here or Coulter.) Anyway, I took your separate page scans and merged the ones that make up just the schematic in to one single big PNG file. There are other pages in your scans that have info besides the schematic so my pic isn't all of it.

I have just uploaded it here:
http://www.xertech.net/pub/NT-50_joined_1.png

Feel free to copy it and add to your page if you desire.

The size is actually smaller than your single page scans. I reduced the pixel dimensions to 1200 vertical and applied contrast to make more black and white. I think it is still quite readable in my version.

Peter Schmelcher · Post by **Peter Schmelcher** » Tue Jan 26, 2021 6:12 pm

Jerry thanks for the NT50 schematic and Rex for combining the sheets, both are downloaded for a future traumatic rainy day.
The information provides lots of clues for trouble shooting my similar NT10.

For the younger fellows, reverse engineering a black box is a miserable repair procedure and even if successful you still can’t be certain that the repair is behind you until you have lots of miles on the repair.
-Peter

Nicolas Krause · Post by **Nicolas Krause** » Thu Feb 04, 2021 9:57 pm

I've hooked in the microcontroller, LCD, and on/off switch on the current schematic. Still lots of details left to verify though. I can't seem to attach the file to the message board but if you PM me I'll happily provide the file to any interested parties. I do have a question about the connectors to the transformers though, I'm not 100% sure on their use. I don't think they're necessary to hook into the microcontroller but I could be wrong?

Post by **ArkadiuszGibes** » Fri Feb 05, 2021 3:35 am

Hi guys

I already made driver for Turbovac 50. You can see it here https://www.youtube.com/watch?v=HPkOAWe2w2c - it's part of my rotor balancing "toy" now.
The project is based on https://github.com/NiklasFauth/stm32-turbotronik - it's not mine. I did some changes to it and it works well. If someone would like i can shere PCBs and schematic. There is also DC/DC (mains/200V) converter that i made for this pump, but it requires to wind the transformer and the one that i used was just some old crap which i took out from old TV. I will try to prepare some more detailed description soon. Im at work now .

Best Regards
Arek

Nikodem Czechowski · Post by **Nikodem Czechowski** » Fri Feb 05, 2021 3:50 am

Hi Arek!

Please do share your schematic and PCB. I thinks this is what I'm looking for for my TMP

Post by **ArkadiuszGibes** » Fri Feb 05, 2021 10:31 am

Hi

Here is a repository with kicad files: https://gitlab.com/arkadiusz.g/turbotronik1.0hw/
However, that was the first version of this driver, so it has some issues. One of them is LDO regulator, there is to much current that goes trough it and it is getting hot quite fast. I replaced it with Chinese dc/dc reg and it's fine - this is not updated in those pcb files.
This is a dc/dc converter that i used - https://allegro.pl/oferta/modul-przetwo ... 7563986495,
Also, as i built in on top of someones else code, it is using lcd that is driven by i2c -> parallel IC. From what iv'e seen, sometimes it was crashing so I had to repleace it with other type of lcd in my case.

Would be nice to update those files with DC/DC instead of LDO, and rebuild it with standard parallel interface for LCD so it could be used with cheap 2x16 displays. I can do this in free time, but feel free to do any modification you like.

Nikodem, I see that you are from Poland, if we would fix those "bugs" somehow then we could send it to production to china, and share some costs for pcbs.

Nikodem Czechowski · Post by **Nikodem Czechowski** » Sun Feb 07, 2021 5:26 pm

I will download the files tommorow and try to do the updates you have mentioned.

What pump you would want to drive it?

We can share the costs, I would ever need 10 pcbs for that - PM me and we can discuss the details.

Post by **ArkadiuszGibes** » Mon Feb 08, 2021 3:47 am

Right now im playing with turbovac 50 pump, but it's damaged and i ordered turbovac360V. I will need to do some changes because TMP 360V works on lower voltage and frequency, but this is in most stuff that can be done by FW modifications. I will also repleace my 200V dc/dc converter to toroid transformer. Please shere the files when you update them.

Thanks

Nicolas Krause · Post by **Nicolas Krause** » Mon Feb 08, 2021 5:29 pm

Hi Akradiusz, thanks for the links and files. If I could ask you to introduce yourself on the welcome forum it'd be a big help. The rules the old timers have setup here really help to preserve the quality of information on the forum!

Post by **ArkadiuszGibes** » Tue Feb 09, 2021 3:19 am

I already did it.

Nicolas Krause · Post by **Nicolas Krause** » Tue Feb 09, 2021 12:32 pm

Oh geez, I'm super sorry, missed that!

John Futter · Post by **John Futter** » Tue Feb 09, 2021 1:39 pm

Nicolas
I have looked at your circuit
I did not use a micro directly to generate the drive frequency due to the danger of a reset or port hang from it.
There is a huge amount of stored energy in a turbo that is why in my diagram it was driven from the 4046 being used as a voltage controlled oscillator through a low pass filter that delayed abrupt voltage changes to the 4046. This filter should be changed to suit differing turbos ie longer time constant for 150 and 360 model pumps. Of coarse you change the buss rail voltage to suit these bigger pumps ie 14 / 28 volts for the tmp 360 and higher current mosfets and dont forget to lower the zener voltage in the buss protector
Fusor use includes high voltage power supplies and there will be the odd high voltage flashover that may reset your micro.
I certainly would not direct drive from a micro a larger turbo than the tmp50 due to the stored energy being released.
Even our turbo controllers have had the PSOC reset and the pump scream to a stop ( that what the big mosfet is for across the DC buss so that the electronics is saved from overvoltage from the motor back emf

Nicolas Krause · Post by **Nicolas Krause** » Tue Feb 09, 2021 1:56 pm

Thanks for the clarification John, I think I've misunderstood something fundamental about the operation of the circuit. I'm going to have to digest your post and look over things.

John Futter · Post by **John Futter** » Tue Feb 09, 2021 11:07 pm

You are doing alright I'm just giving a bit of sage advice learnt from doing wrong it in the first place

ask away and i'll answer

Nicolas Krause · Post by **Nicolas Krause** » Fri Feb 12, 2021 12:43 pm

Hi John

I have a TMP 50 so I'm dealing with one of the smaller pumps. But my general understanding of the circuit is that you use some discrete logic to generate the signals which drive the half bridge connected to the 3-phase motor of the pump. I had assumed that hooking up the microcontroller to the logic chips you'd used would have provided enough of an innate buffer to prevent damage to the microcontroller. Looking at my circuit again and your comments I assume the problem is with the current measurement portion of the circuit correct? I expose the microcontroller to large changes in voltage/current at that point. If I included some sort of opto-isolation on that connection would I avoid the problem? I've never used opto-isolation in a current sensing application before.

John Futter · Post by **John Futter** » Fri Feb 12, 2021 1:16 pm

Nicolas
It is hard to use linear optos to get volt and current sense across I make sure that there is series impedance then 5 volt TVS diodes across micro I/O pins

my comments were directed at some of the other posts where micro derived drive signals are use to drive the half bridge directly
a TMP 50 has about the same energy as a .22 LR cartridge where as a TMP150 is more like a .308 cartridge amount of stored energy

Nicolas Krause · Post by **Nicolas Krause** » Sat Feb 13, 2021 1:02 pm

Thanks for the clarification John, I've added the suggested circuit protection, now I just have to spec everything and layout the board! That's a nice way of thinking about energy as cartridge size, it's been awhile since I've been on a range but even though .22 LR is small I wouldn't want to be hit by either.

Post by **Michal Dvoracek** » Wed Apr 21, 2021 5:59 am

Hello,

I'm finally built up my turbo controller which is inspired by John's but it also contains speed measurement control.
I'm attaching some photos and video is here: https://youtu.be/OWJsfk7cNfQ

Regards,
Michal

John Futter · Post by **John Futter** » Wed Apr 21, 2021 2:58 pm

Excellent
looks similar to mine. I could not post the digital controller as it was code written at work hence ip problems ..

But well done

Post by **Richard Hull** » Wed Apr 21, 2021 4:36 pm

Michal, a true love's labor and a grand win. I applaud both your and Nicolas' effort in electronics. I call it the hands on imperative or a "doer", doing. The epitome of the thrust of this site and of real amateur science is obtaining and retention of hard won skills that not only make life more full and rewarding, but in the making of a whole, capable person. You can be proud of your effort, you have earned the right to pride of accomplishment. Also laudable is the aid offered by John Futter and others in the quest.

I am sure that all here realize this is but a micro win in a demanded technology, (obtaining a scientific vacuum), along the road to the fusor and fusion quest here. One must never underestimate just how tough, costly, and demanding this amateur effort is to one's time and purse required for the acquisition of both knowledge and materials. It is not for kids. Big boy pants are needed if this task is taken on by any individual.

In the end, a win is laudable, but a win with useful experiment applied to the win is the ideal.

Note: the pep-rally is over. You can all get back to it....

Richard Hull

Nicolas Krause · Post by **Nicolas Krause** » Thu Apr 22, 2021 2:06 am

Very nice Michael! Would I be able to see your code and schematics? Always interested in seeing how problems I have to solve were solved!

Nicolas Krause · Post by **Nicolas Krause** » Mon Jan 03, 2022 8:33 pm

Just a quick update here. I've specced all the components for the Turbopump controller over the christmas break and now I'm getting in to the PCB layout. Lots of little details left to work out!

Dennis P Brown · Post by **Dennis P Brown** » Thu Jan 06, 2022 2:19 pm

Extremely impressive; your own design (yes, inspired by John's)? This is rather advanced level electronics driving a turbo - they are not simple motors. This is EE level work. That doesn't even cover the actual execution/build you've done.

Nicolas Krause · Post by **Nicolas Krause** » Tue Jan 11, 2022 11:56 pm

Thank you for the compliments Dennis, I still have to get it to work! The circuit is John's design, I've added a microcontroller to run the whole thing, but that's it.

Nicolas Krause · Post by **Nicolas Krause** » Mon Feb 07, 2022 8:52 pm

I've completed most of a first draft of the routing of the board. I can post the KiCAD files if anyone wants to take a look but some details still need work. This is the first time I've routed a 4-layer PCB and a board of this complexity. I'd appreciate any constructive criticism more experienced hands might have to offer.

1. Is there a rule of thumb for controlling trace size given the power running through them? I've made the traces going out to the motor much bigger, but I have 5V, 15V and then motor power traces all running on this thing, and I haven't changed either the 5V and 15V traces
2. For a 4-layer PCB I've made one of my planes the ground plane, and was planning on making the second some sort of power plane. I assume I should make it the power plane for the power traces supplying the motor, is this correct? Or should it be the 5V or 15V power plane?
3. Is it generally acceptable to put component labels inside the outline of a component? I'm having trouble getting all the labels to be visible.
4. How do I size vias for different trace sizes, so far I've just been using the default settings in KiCad, but that clearly won't work for my thickened high power traces
5. Any general constructive criticism about the layout of the board and the traces would be much appreciated!

Joe Gayo · Post by **Joe Gayo** » Mon Feb 07, 2022 9:10 pm

Saturn tools for trace calculations ... https://saturnpcb.com/saturn-pcb-toolkit/

Think about where the high current loops are and make those as tight as possible.

The power plane can be split amongst multiple voltage rails.

There is an excellent video on PCB layout about how power actually travels in the dielectric space. https://www.youtube.com/watch?v=ySuUZEjARPY

Nicolas Krause · Post by **Nicolas Krause** » Tue Feb 08, 2022 7:13 pm

Thank you Joe, lots of good stuff to work through and learn! That PCB layout video is fantastic! I'm only a 1/4 through but so far it's been hugely enlightening.

John Futter · Post by **John Futter** » Wed Feb 09, 2022 8:28 pm

Nicolas
that looks pretty good
ie no input lines to micro going anywhere near the 3 phase output driver
you will see that the motor peaks at about 1 amp during rampup ie a hundred odd watts and with no gas load settle to about 6-11 watts at full speed.
have fun
oh and if it turns the wrong way interchange any two of the 3 phase outputs

Nicolas Krause · Post by **Nicolas Krause** » Sun May 22, 2022 6:43 pm

Just a quick update on the progress of this controller. I've received the first draft of the PCB in the mail, and had built up nearly the complete board before discovering a couple of errors which means I'll have to do a second revision. They are as follows:

Double placed one footprint (see if you can find it!)
Polarized capacitors are packed too tightly, I cannot place all 5 with the current footprint layout
Holes for a diode bridge are incorrectly sized and the component does not fit

I've got a little cheap hot air setup here, so I figure I should be able to salvage all the bits without too much trouble.

John Futter · Post by **John Futter** » Sun May 22, 2022 11:45 pm

Drat
comes to mind

Post by **Richard Hull** » Mon May 23, 2022 2:20 am

I have put out a few custom boards and stupid mistakes are common and all part of the learning experience. The last two designs I had run were perfect. All the best in the rework. It is obvious you can save this first pass using good skills in work around assembly.

Richard Hull