Tyre machine, IGBT and thermistor help

[eddie49]

as soon as I plug it in it blows the fuse in the plug.

So this machine is single-phase on a 13A plug?

The board may be a single-to-three-phase inverter. The motor may be 3-phase with a built-in variable frequency drive - "VFD", so that it can run on single-phase 230v ? If so, the faulty board could be replaced by a generic external box.

The motor control board is marked "Laser SSE35", which is Laserelettronica, Italy. What is the make and model of the whole tyre machine?

 

[e5c0rt.mk1]

It is a 2018 sice s43, single phase.

There are 3 wires going into the motor from that circuit board, and three switches on the machine feeding into it, slow, fast and reverse.

I suppose it could be done away with and replaced with a vfd. Might be the cheapest option in the end.

 

[eddie49]

Yes, the board is a VFD - I should have seen the three "U, V, and W" phases!

SICE tyre machine breaking for spares:

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Inverter repairs:

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[eddie49]

It is probably more convenient to try to fix this board, rather than replacing it with a general-purpose VFD, since it is already set up with the slow, fast, and reverse push-buttons.

These IGBTs with the part number RGTH60 TS65 :

5PC RGTH60-TS65 RGTH60TS65 58A650V | eBay

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seem to be the same spec as the part without the "H" after RGT ( 650v, 58A, 194W ), and a lot cheaper. If you are prepared to take a chance on this rather dodgy-looking Seller, that is the price for five!

The damaged thermistor is probably part of the soft-start/precharge circuit, and maybe gets bypassed by a relay after the capacitors charge. There was probably too much load on the thermistor, due to the shorted IGBT(s).

The problem with replacing IGBTs is that when they go short, they often conduct high voltages from the collector/emitter circuits through to the gate, blowing the gate driver circuitry as well. Then a newly-installed IGBT with the gate driver still damaged can self-charge the capacitance of it's floating gate, conduct fully on, and blow itself up again. Therefore as Jan-DIY said, you would need to investigate and check the components on each gate before risking new IGBTs.

The component on the heatsink to the right of the IGBTs is the bridge rectifier. This takes AC mains in, rectifies it, and puts 325v DC across the two large black electrolytic smoothing capacitors.
A safe way to approach this problem is, instead of the AC mains and the rectifier, to disconnect the output of the rectifier and use a low voltage current-limited DC supply, of about 30 volts, connected to the + and - tracks where the rectifier was, then check for valid control signals on all the IGBT gates. The low voltage and limited current allows you to debug the gate circuits without blowing the new IGBTs.

 

[minimutly]

It is probably more convenient to try to fix this board, rather than replacing it with a general-purpose VFD, since it is already set up with the slow, fast, and reverse push-buttons.

These IGBTs with the part number RGTH60 TS65 :

5PC RGTH60-TS65 RGTH60TS65 58A650V | eBay

Find many great new & used options and get the best deals for 5PC RGTH60-TS65 RGTH60TS65 58A650V at the best online prices at eBay! Free delivery for many products!

www.ebay.co.uk

seem to be the same spec as the part without the "H" after RGT ( 650v, 58A, 194W ), and a lot cheaper. If you are prepared to take a chance on this rather dodgy-looking Seller, that is the price for five!

The damaged thermistor is probably part of the soft-start/precharge circuit, and maybe gets bypassed by a relay after the capacitors charge. There was probably too much load on the thermistor, due to the shorted IGBT(s).

The problem with replacing IGBTs is that when they go short, they often conduct high voltages from the collector/emitter circuits through to the gate, blowing the gate driver circuitry as well. Then a newly-installed IGBT with the gate driver still damaged can self-charge the capacitance of it's floating gate, conduct fully on, and blow itself up again. Therefore as Jan-DIY said, you would need to investigate and check the components on each gate before risking new IGBTs.

The component on the heatsink to the right of the IGBTs is the bridge rectifier. This takes AC mains in, rectifies it, and puts 325v DC across the two large black electrolytic smoothing capacitors.
A safe way to approach this problem is, instead of the AC mains and the rectifier, to disconnect the output of the rectifier and use a low voltage current-limited DC supply, of about 30 volts, connected to the + and - tracks where the rectifier was, then check for valid control signals on all the IGBT gates. The low voltage and limited current allows you to debug the gate circuits without blowing the new IGBTs.

All this is fine - and correct in that you do need to check the drivers of all the IGBTs, I’ve used 5W filament lamps for this in the past - very effective because you can see the difference in brightness which indicated an on all the time driver. However, it needs some dexterous soldering on your part here. Getting this right is more tricky than you might think.

 

[e5c0rt.mk1]

I took the chance and replaced the igbt and thermistor, hoping it was a cheap-ish fix, plugged it in and it just blows the fuse and trips the breaker.

Everything still looks alright on the board, so I think I'll have to get someone who knows what they are doing to have a good look at it, as it getting beyond my skills to do anymore to it.

 

[Jan-DIY]

And you did what mentioned? Checked all caps, z diodes, gate resistors?

 

[e5c0rt.mk1]

Bit of an update on this. Sent the board away to get repaired. It still didn't work when it came back. Sent it away again and once again it wouldn't work. So I have ended up buying a cheap vfd off ebay.

Took abit of setting up but its nearly there. Only problem I am having is sorting the settings out, to stop it stalling and putting err1 on the vfd when the tyre is at it tightest coming off the wheel.