Más sobre el regulador

[Gianola]

Me acaban de pasar esto y voy a echarle un vistazo:


http://www.electrexusa.com/Images/VFR_tech_story.doc



VRF Regulator Rectifer Basics
Inside there is a sox diode full wave rectifier, and every phase input can be switched to ground through a thyristor. The thyristors are switched by a regulator circuit that measures the DC output voltage from the rectifier bridge. We call this a shunting regulator. It is a very simple system, and doesn't work very efficient, but it does the job while not dissipating too much heat. That is why all OEM manufacturers still use this setup.

As you know the VFR has a problem in the charging circuit. There are a few reasons for this. First of all the regulator relies on the frame of the bike as it's heatsink. That in itself is not bad, as long as there is good thermal contact between the diodes and thyristors inside the unit to the housing, and as long as there is a good thermal contact between the housing and the frame. If that is taken care of, the heatsinking capabilities are just as good as an RR unit with a large built in heatsink.

The problems in the VFR system is as follows:
Problem #1 is the heatsinking to the frame. Our RR30 replacement unit needs to be mounted using white heatsinking paste, the same stuff that is used in fitting power transistors on cooling elements in amplifiers. We did quite a bit of testing using thermocouples that we built inside the RR before filling it with epoxy. That way you can test the temperature where it is most critical, on the components themselves. Honda should have fitted all their OEM regulator/rectifiers with some of this compound on the back. The RR30 unit also has excellent heatsinking from the components to the housing. That is the main feature in all of our regulator/rectifiers.

Problem #2: The stator is a high power unit. It resides in the heart of the very compact V-4 motor, and therefore it gets quite hot. The stator is used in the CBR models as well, and these bikes also use the same regulator/rectifier. CBR's have far fewer problems using the same setup. My idea is that the main difference is the location of the stator. The CBR is a line engine, and the stator is mounted on the end of the crank. It will not get as hot as the VFR model. Then Honda uses a delta wound stator. The voltage output of this stator is lower that from a comparable star wound unit, and the current output is quite a bit higher.

As you guys also have found out, quite often when a regulator/rectifier fails, a new one will fail after a fairly short time. It is a recurring problem (not on all bikes, but I have seen it quite often). The stator has 18 poles, 6 per phase. Every poles has (I don't know by head exactly) 20 turns of copper wire on it. In between the phase outputs in a delta wound system you will have 120 turns. Because of the hot spot in the engine, the copper winding's insulation starts to fail after some time. Most likely that will be somewhere from  one layer of windings to the next layer on a pole. This usually happens only under load and when the unit is hot.  Imagine a few of these shorts in between the phase outputs. You will have not 120 turns but say 50 or 60. The complete charging system will still be able to reach 14.4 Vdc, it is rated for about 400W.

As you know, when you have a transformer with only a few thick windings, you will get a very low voltage and a massive current output. The same happens in the VFR Delta stator. Those 60 turns will give a much lower Vac but a much higher Iac. And diodes in regulator/rectifiers don't like high currents. If they are rated for 35 Amps (like the ones we use in our RR30's) they can handle that whenever they get sufficient cooling. When they run hot, the max current they can handle drops down quite a bit, which makes dissipate even more heat, and finally one of the diodes fails! The stator we supply for some of the VFR's is wound in star. The total power output is about the same as the original (lower Iac times higher Vac makes about the same... I know this is simplified, there  is more to it....). But there is always two phases in between the phase connections. (=240 turns) The Vac is higher, and the Iac is lower. Even if there would be a short in between some layers of turns (I haven't seen that happen) you still wouldn't have the current output of the original stator, which is what destroys regulator diodes.







So far this (still unproven!) seems correct. It is difficult to prove, as you need to check the original stator for shorted windings whenever the systems is under load, and very hot. And it doesn't need to do it all the time even! Bikes that have had a few failing RR's stopped frying them after replacing the stator.

One last thing:

Problem #3:The output of the RR is fed through the wiring loom and some sort of junction box to the battery. Make sure you have perfect connections here. I found a number of problems with voltage drops over these lines. Check our fault finding chart on http://www.electrexusa.com It will guide you through the process. The best thing to do, if you see any voltage drops in between RR and battery (we are talking high current here, so any bad connection will give a significant voltage drop) is to feed the ouput of the RR straight to the battery terminals using a (good quality) inline fuse.

We hope this information has been helpful to you.


Best regards!



Ritzo Muntinga