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EC Brake control circuit  

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(@rared)
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I'm thinking of duplicating your eddy current brake control circuitry (attached) as the hardware to drive a couple of Telmas on a hub dyno I'm building, one dedicated circuit per hub initially
 
 
While I've the ability to construct such a relatively simple device, I've certainly not got the knowledge to design it, so wanted confirmation of certain things
 
 
I'm basically using identical critical components, Optocoupler HCPL 3120  and IGBT CM200DY 12H, as per your circuit as they suit my purposes well, and are inexpensive to build
 
 
Can you please confirm the values of the capacitor and resistor, it looks like 0.1uf and 3.1ohms respectively but I may be wrong, between the optocoupler and IGBT
 
 
Any other tips in putting it all together ?
 
 
Jostein said that you had had no problems with your eddy current brake control circuit (controlled in turn by the 'YourDyno' box) in use, although he also commented IGBT drivers can sometimes be 'noisy', but you had not reported any problems 
 
 
Thanks in advance for your help in all this, it's the last piece of the puzzle for me, everything from rebuilding of the Telmas to construction of the drive system and frames etc etc will be done by myself from scratch
 
 
I'm happy to give credit for any help you can give
 
 
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Posted : 10/05/2020 2:34 pm
(@rared)
Member

Ok ...... maybe until confirmation of the above, I'll ask a supplemental question that someone might help with :

 

I'm under the impression, rightly or wrongly, that the link component between the 'Eddy Current power control driver' discussed above and the 'YourDyno blue control box', namely the 'Optocoupler' (breadboard circuit), due to it's intrinsic design affords a margin of isolation therefore protection to the 'YD bcb' ?

 

Being an 'optical' device, feedback (spikes etc) form the 'EC pcd' back into the 'YD bcb' is inhibited or prevented ?

 

TIA, John

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Posted : 11/05/2020 8:54 am
(@rared)
Member

Right ..... and apologies for this ...... for those that may be interested :

 

The capacitor value is 0.1 uf according to the HP HCPL 3120 data sheet, which concurs with the above

 

It gives you the calcs to determine the gate resistor value, but .......

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Posted : 11/05/2020 10:10 pm
(@rared)
Member

 ...... browsing the Mitsu IGBT data sheet it's simply stated as 3.1 ohms, which concurs with the above

 

So that answers that, lol, unless someone's got something to add ...... 🤪

 
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Posted : 11/05/2020 10:15 pm
(@mach_1)
Member

Subscribe with interest to this thread ! So you're  building the whole lot ?

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Posted : 12/05/2020 4:28 am
(@rared)
Member

Mach_1 ..... yes thanks, unfortunately I'll probably be around for a while, lol

 

My own idea for a hub dyno goes back some years, I've had the Telmas more than fifteen, 'bout time I did something with 'em ....... you could pick them up for pennies back then

 

There's a nice Aus built one on YT, pretty much how I envisaged the job all along but with a few alterations ..... so mine might look a bit like a 'copy' when it's been sketched out for a while now

 

'Rear' axle will be hybrid CC160s, then following that 'front' will be CC80s, once I've obtained the second one

 

I'll be doing everything except Josteins bit hopefully, spare EC drives on hand etc ...... I like to fix my own stuff when it goes wrong if nothing else

 

The capability to couple the two axles (four brakes) from one controller would be nice ..... I've seen the latest YD box now controls 4 brakes / 2 rpm but don't think that's across two axles ?

 

I've a 'new' Froude AG150 to do then, replacing the old Texel control, and then an ancient G4 once I've got a better handle on the whole deal

 

It'll keep me out the pub, if nothing else ....... 😀 

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Posted : 12/05/2020 6:39 am
(@mach_1)
Member

Sounds like your a Ozztralian ?  " Pub " ?

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Posted : 12/05/2020 10:44 am
(@rared)
Member

No mate ....... not a colonial ......

 

Not that you can 'go down the pub' at the moment ennyhoo ....... lol 🤪 

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Posted : 13/05/2020 9:48 pm
(@mach_1)
Member

LOL ...... I'M  sure once the queen of Great Britain stop living Australia will breakaway from her clutches and become a free country.

 

Curiously what country are you from ?

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Posted : 14/05/2020 2:46 am
(@rared)
Member

English, mate ...... not that it matters much in this wonderful global collective that allows a resource such as this .......

 

Anyway, most of the parts are either with me on or on order, so once I've freed myself up a little, I'll crack on

 

One of the first jobs is to disassemble, test, 'blueprint' (for want of a better term), reduce the tolerance stack, and rebuild the Telmas

 

One's a CC135 and t'other a CC160 ...... plan is to hopefully get them up to around 1800nm apiece

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Posted : 14/05/2020 7:43 am
(@admin)
Member Admin

@rared,

Good discussion! A few answers:

Posted by: @rared

I'm under the impression, rightly or wrongly, that the link component between the 'Eddy Current power control driver' discussed above and the 'YourDyno blue control box', namely the 'Optocoupler' (breadboard circuit), due to it's intrinsic design affords a margin of isolation therefore protection to the 'YD bcb' ?

You need a driver for the gate of the IGBT transistor. The optocoupler isolates YourDyno from the power, which is good since there are large currents involved and you may not have the same ground potential as YourDyno. 

The CM200DY-12H has two transistors each with a flyback diode included. Transistor 1 is off (by shorting G1 and E1), but its flyback diode is important. It is used to provide a path for the current when Transistor 2 turns off. 

An improvement to the circuit is to add a power resistor in series with the diode. This makes the stored energy burn off quicker, thus enabling the current (brake torque) to be reduced quicker. This is not possible with the CM200Y-12H since the two transistors are mounted back to back. You can choose a single IGBT and a single Diode then you have that opportunity. Make sure to size it properly in terms of its ability to absorb energy. 

If you like to play with these things, I recommend LTSpice!

Nice to follow your progress, keep us posted!

 

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Posted : 15/05/2020 5:33 pm
(@rared)
Member
Posted by: @admin

 An improvement to the circuit is to add a power resistor in series with the diode. This makes the stored energy burn off quicker, thus enabling the current (brake torque) to be reduced quicker. This is not possible with the CM200Y-12H since the two transistors are mounted back to back. You can choose a single IGBT and a single Diode then you have that opportunity. Make sure to size it properly in terms of its ability to absorb energy.

 

Do you /anyone have a circuit diagram for that ?

 

I'm 'belt and braces' so tend to overbuild everything ..... the IGBT / Bridge I'm building has a power factor of 3+ over the amp draw of the soaked Telma

 

Jostein ...... are there any plans to release a YD box that controls four brakes over two axles ? Linux .... lol ?

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Posted : 15/05/2020 7:09 pm
(@admin)
Member Admin

Hi, 

4 brakes are already supported :-)! Need 2 YourDyno boxes, one for each axel. 

See this circuit diagram. Don't pay attention to the exact component part numbers, those need to be selected carefully. 

I did some simulations now. This circuit is quite fast, even without a resistor. The simulation attached is with a Telma CC160. 

If you want to add a resistor, put it in series with the diode.

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Posted : 15/05/2020 8:33 pm
(@rared)
Member
Posted by: @admin

4 brakes are already supported :-)! Need 2 YourDyno boxes, one for each axel. 

 Jostein, yes thanks, from reading an earlier thread I was aware of that ...... is it possible to sync the two boxes via the software to come up with a single output ?

 

Posted by: @admin

See this circuit diagram. Don't pay attention to the exact component part numbers, those need to be selected carefully. 

I did some simulations now. This circuit is quite fast, even without a resistor. The simulation attached is with a Telma CC160. 

If you want to add a resistor, put it in series with the diode.

 

Excellent, thanks .....

 

'selected carefully' : Does that mean they can be simply overrated or have to be carefully 'sized' ?

 

If desired, how would you determine the value of the resistor ?

 

The data sheet of the R6020PNJ shows the gate voltage as +30v- ...... I assume these are maximum values and that 5v would drive it ?

 

Or would you still drive the gate via the optocoupler circuit discussed prior (15v), thus retaining the preferred isolation characteristics ? If so, would the gate resistor still be 3.1ohm ...... if not how would you determine the value ?

 

Apologies for all the questions, I'm guessing you're quite busy anyway, but I would imagine a proven home built eddy current brake power drive system, using relatively up to date components, would be of interest to a fair few people constructing their own systems ......

 

All the best ...... John

 

 

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Posted : 16/05/2020 10:57 am
(@admin)
Member Admin
Posted by: @rared

'selected carefully' : Does that mean they can be simply overrated or have to be carefully 'sized' ?

What I meant is that the components used in that simulation is just for a quick general test, they will not work in real life, because they are not rated for the power and voltages. The simulation still works well. 

Here is a good document to study if you want to learn about IGBT designs: 

https://www.fujielectric.com/products/semiconductor/model/igbt/application/box/doc/pdf/REH984e/REH984e.pdf

You cannot drive the gate with 5V, you need much more, typically 15V. That (plus isolation) is why there is a gate driver in the circuit. 

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Posted : 17/05/2020 1:37 pm
Sanec liked
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