Fusor Forums

Hi everybody im new to the forum,
as you can imagine im currently trying to build a vacuum chamber to gain konolowege and in the far future turn it into a fusor.
Last weekend i managed to get hold of a pfeiffer TMH-260, very dirty and with a broken ceramic bearing but still i think is reusable


You can see the only damage in the rotor is a small bumb in one of the blades.

Im coming to you asking for imformation about the driver, conection voltajes etc etc,

BTW, English is my second languaje so dont hesitate to correct me.

gcr100
I would fix your login name as per the rules PDQ
You should have also introduced yourself in the correct forum

I hope there is more of it than just that...

Bearings likely available from Alpine Bearing. Expect to pay hundreds of dollars.

You'll need to balance the rotor. There are some cheapish tricks you can use for this.

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thanks to Rex for this

thanks i think its fine now, does anyone here know the pinout for this particular pump?

Hi Gustavo,

Finding the correct wiring can be a real pain - also it might need 3-phase power to run. I tried this with my TMH pump and ended up just resorting to buying the controller. You might end up having to do the same.

I've attached the pump's manual, that might be of help to you.

Also, unless you've just disassembled the pump its missing atleast the stators and the rotor housing, maybe more.

i have read a the manual a few times before posting here, but i cant fin the pinout anywhere, the point of that is to make the controller (i have a little experience making triphasic motor controllers for BLDC motors), but without knolowedge about the array of coils i dont thing i can.

A lot of pfeiffers are two phase. You will have pins for that, an eeprom, and a temp sensor. I am not sure if they have halls.

At least 6 pins have continuity between them .5 ohms or so, this confuses me a little, because not all 6 have the same resistance, probing with the meter some have .2 ohms.
I dont have an lc meter to acurate measure the inductance of the coils, may be the best idea is to disassemble the pump, pull out the stator coils and see how its arranged.

this is the connector,

well this seems promising i disassembled the lower part of the pump to check the windings.



there is a bundle of cables going from the windings to the connector,



5 cables on this bunch are thicker, the yellow one is even more, there is a thin brown cable that seems to be a temperature sensor it goes in & then out.
The pump indeed seems to have a bipolar motor

this past days i have been thinkering about the pump and how is connected



there are 19 pins on the connector, 5 for the coils 1 grounding the body, 2 that have a 1.5K restistor between them,



Using arduino i managed to isolate the cables that i think are the hall sensors,

AND bingo there they are,

Some progress:

https://youtu.be/K9TtlXswLts

Don’t let the pump run that long in atmosphere. Good job otherwise.

Hi Gustavo,

it looks like you figured it out, but in case it's any help note that the pinout of the motor's connector and its internal circuit are shown on p9 of the user manual for the TCP380 controller (you will find PDF via Google). I don't know what those two components with a Theta symbol by them are. Maybe the resistor shown from pin P to N is a thermistor.

I can also see the service manual for the TCP310. It uses IR3525A PWM controller ICs. I wouldn't fancy trying to replicate a controller from scratch but I wonder that a generic motor controller board could be adapted using the knowledge from the manuals. How did you get on?

Regards
Chris

hi Chris i left the project long ago and now im retaking it, normally i dont run these pumps on air for too long, now the pump runs at about 30krpm, but if i go higher the mosfets die really quickly, im working on an improved version, when its ready will post full schematics for those who need it, seems that this specific model is very common ie seen this go for relatively low prices and are kinda easy to drive i did not have a scope previously so i was working kind off blindly.
I have most of the tools to troubleshoot this issues at the moment.

I've picked up one of these turbos (TMH-260) as well for pretty cheap and seems in good condition. I'm putting together a motor controller as well. I've spent the past year or so doing several motor controller projects, so happy to help out! Mosfets dying could be a number of things, but hard to say without looking at the design.

I'll post the schematic tonight, but i have my suspicions, it could be underdriving the gate.
Been very busy with another pump driver for a small leybold one which is almost finished.

Ok here's the shcematic i was using about 30khz pwm frequency, i may add a current sensing chip later just to be safe
Im not sure why eagle exports the image with lines that thin, its kind of hard to see them

I have several questions but the most important observation is that you may need diodes from each motor phase to 40 V, as in the attached schematic for a unipolar stepper driver.

Without that, you'd be getting inductive voltage spikes every time a mosfet turns off. These spikes can very easily kill the mosfets. The zener/avalanche diodes (D1-D4) probably aren't doing anything to protect the mosfets from these spikes:
1. They probably lack the ability to actually carry the amount of current required here (up to 7-8 A spikes, or 1-2 A continuous)
2. Their breakdown voltage (120v) is higher than what the transistors can tolerate anyway.

Not sure why i wrote IRF530, Im actually using IRF630's,
When i started working on this controller i actually was using Flyback diodes instead of Zeners to disipate the energy, however i noticed that the common wire was heating up, which stopped after switching to the zeners, the ones im using are 1N5381B
On the board i forgot to ad a few resistors and the gate protection zener, i bodged them on this last effort.

COM wire overheating is due to the following reason. Each motor winding acts like a transformer. Whenever a half-winding is on, the other half-winding has opposite voltage across it, and now because there's a diode across it too, the transformer is effectively shorted. Current grows through the motor winding without bound.

The solution to this is to instead have the flyback diodes go from the transistor drain to 2*V_supply (80V), rather than 40 V. It's hard to explain this briefly in words, it's best to see this in action in the circuitjs app: https://tinyurl.com/yg3y5ue7
(The transformer is simulating one of the two motor windings; the 20 ohm resistor is simulating the 'load' on the motor).

The switch is set to '80V', if you instead flip it to 40V you can see the current build-up effect occurring.

If the supply doesn't have 80V output, you can 'simulate' it by having a capacitor with a 80V zener, like follows: https://tinyurl.com/yje82yck

The 100 ohm resistor is just arbitrarily chosen; I actually don't know the right value to use here. It would have to be calculated based on allowable voltage drop and dissipation.

That circuit will both properly snub the voltage spikes and dampen the current spikes through the components.

Well thats seems familiar, thats the topology of a switch mode power supply, to be honest the zener diode idea i took from another guy, seems to work for him, not sure why my implementation is giving me problems.
I will do some measurements and report back.
Thank you Al for your input on this