28amp VRR temp measureements

[Oldschool1]

I am going to instrument my VRR (28 AMP) to get some temp data on it in different cooling configurations.

Yes it might be lost hope - but i'm a thermal engineer and well you know how it is!

Does anyone have a cross section picture of the VRR (internal component layout) or understand the physical construction. I need to understand this for strategic placement of the TC's.

My guess is there is a PCB (populated with caps diodes, FETs) mounted to the aluminum plate and then potted a polymer. The best case for heat transfere out would be that the heat sources are thermally conducted to the aluminum plate.

Anyway - any data would be helpful. If I new the exact components we could get real scientific and determine the MTBF as function of temperature then correlate that to the temp of the components - ok I've gone to far again for this project. But that's what we would do in the thermal design process to establish the design criteria then design a thermal solution (cooling) to meet that criteria.

Thanks,

Paul

 

[Don]

Rather than monitor the temperature of the unit itself (I'm sure the rectifier/regulator's heat sink was designed to handle the heat produced by the alternator continuously putting out it's full rated 28 amps while riding across the Sahara Desert) I think it would be more informative to get a thermocouple as close as possible to (or even into) the two connectors nearest the alternator . . . . the field connector with the black and white wires and the stator connector with the 3 yellow wires - I suspect that more failures of the alternator and/or regulator are due to electrically dirty connectons within those two connectors. The weakness of the design is that those 5 wires all carry lots of current so even a tiny bit of resistance in a dirty connection will create heat, making the connections even worse. If you sense temps significantly above ambient at either of those connectors, I suspect you're going to see a system failure before too long

Don

 

[Oldschool1]

I like this concept - 4th TC added to the mix. Well that only allow me to get temp data on a single conncetor - i'll think more about this.

All this, may not change the game, but at minimum it will answer some questions.

Thanks for the thought on this.

Rather than monitor the temperature of the unit itself (I'm sure the rectifier/regulator's heat sink was designed to handle the heat produced by the alternator continuously putting out it's full rated 28 amps while riding across the Sahara Desert) I think it would be more informative to get a thermocouple as close as possible to (or even into) the two connectors nearest the alternator . . . . the field connector with the black and white wires and the stator connector with the 3 yellow wires - I suspect that more failures of the alternator and/or regulator are due to electrically dirty connectons within those two connectors. The weakness of the design is that those 5 wires all carry lots of current so even a tiny bit of resistance in a dirty connection will create heat, making the connections even worse. If you sense temps significantly above ambient at either of those connectors, I suspect you're going to see a system failure before too long

Don

 

[saaz]

There has been a fair bit of research on this in relation the VFR, so doing a search on that may help. Someone went through various cooling methods with temperature measurements. From memory a cooling fan from a computer worked well.