The Great KB Regulator & Rectifier project. [Archive]

davereid

4th September 2008, 08:13

To start the ball rolling...

Design #1 - The burn-yer-leg off shunt regulator
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Use 2 x MJ150037 power transistors, wired as a darlington pair. In this configuration the collectors are connected together, the emitter of the first transistor feeds the base of the second, and the emitter of the second is ground.

These transistors can handle a whopping 20amps, and have a minimum current gain of at least 25, so in our confguration you could expect a current gain of at least 600.

So we need a base current of about 30mA to push these transistors full on.

Use a 12 volt zener, like a 1N5349, at 5 watts. this can handle 400mA, so is easily up to the job.

Wire it in series, cathode to positive with a 120 ohm resistor, connecting the base of the first transistor to the positive supply, and you have a simple shunt regulator.

Good for 20+ amps if placed on a large lump of steel as a heat sink and costing under $30.

But... relies on stator have at least 2 ohms effective winding resistance, and needs a separate rectifier....may need to try several zeners, even up to 14volt models to get effective charging.

CookMySock

4th September 2008, 11:52

Considering how much cheaper switching FETs are, it might be worthwhile looking at a switching design as well, particularly for the larger alternators (mine is 400watts - 30A.) There are other benefits, such as it will act as the rectifier as well, longer stator life, lower torque on from the engine at full revs, lower component count. But yeah there should be a basic one first.

edit: This <a href="http://www.linear.com/pc/categoryProducts.jsp?vin_min=40&vin_max=80&qpsActive=true&action=INITIAL&vout=13&filterOnInit=true&iout=10&navId=H0%2CC1%2CC1003%2CC1042&referringUrl=%2Fpc%2FcategoryProducts.jsp&y=0&x=0">search</a> at linear.com shows two suitable devices for input voltages of 100V and outputs of 12V 20A. I wonder if many stators will exceed this voltage. The device should current limit at 20A - unfortunate for a 30A capable stator. Useful on race bikes, as it is nearly weightless, and it will unload the stator when no load is being used.

Steve

avgas

4th September 2008, 12:19

hmmmm build it yourself seems rather an interesting concept.
While not impossible - i'm gonna steer clear from it.

Old bikes it would be fine, but my experience with putting high power electronics into new vehicles says that the likes of Yamaha, Honda, Toyota..... spend far to much time letting BOSCH etc worry about the hamonics etc.
So be sure guys that you chuck in enough 3rd and 5th harmonic sinks (RC circuits will be fine) so that the poor bike battery etc doesn't bake trying to deal with it.

Also this thread is useless without schematics people

davereid

4th September 2008, 16:51

Old bikes it would be fine, but my experience with putting high power electronics into new vehicles says that the likes of Yamaha, Honda, Toyota..... spend far to much time letting BOSCH etc worry about the hamonics etc.
So be sure guys that you chuck in enough 3rd and 5th harmonic sinks (RC circuits will be fine) so that the poor bike battery etc doesn't bake trying to deal with it.

Also this thread is useless without schematics people

Ask and ye shall receive.. pdf schematic attached.

Transistor is rated to 1 Mhz so it will easily clean up any harmonics from the alternator, and as we dont switch anything, we arent making any.

Costs..
Jaycar has transistors each at $8.90, Zener $0.45, resistor $0.06 heat sink... up to you, total about $20.

k14

4th September 2008, 17:02

notme

4th September 2008, 17:48

After Dave and I started discussing this, I was thinking that a better solution (note that "better means different things to different people!) would be a small 8 pin micro monitoring voltages and currents, and controlling the charge level.

Moving the control to a micro means that once a power circuit is set out, a lot of future improvements will be software only.

The thing could log battery charge and warn when your battery is on it's way out, or when the charging system suddenly isn't charging, and allsortsastufflikethat(tm).

Could also have different profiles selectable, e.g. "normal" maintains the battery to the best of it's ability, but "race" takes the minimum power possible from the engine.

notme

4th September 2008, 17:58

Ok, you brainy electrical types. How do I make me one of these (see attachment). At 60 quid a pop you could probably make some $$ if you worked out how to do it properly. I'm guessing the components are only worth $5.

It's a simple DC/DC converter. Looks like it's a step down (buck type) only, and it's probably not isolated.

So how you build one is you get a switch, inductor, and a diode and control them in the right way. :shifty:

Rather than designing and building one - since this is a specialized application I would look for a cheaper version of the same thing. It's amazing how much of a price premium people will charge for a "compact electrochemical energy conversion device" just because most people don't know that all they are getting is an AA battery.....

In the same manner, this "RS125 voltage regulator" is a generic DC/DC converter, much like the ones linked below that are a weeeeee bit cheaper:

http://www.jaycar.co.nz/productView.asp?ID=AA0218&CATID=&keywords=converter&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

Oh and the material cost of even the jaycar one? You don't want to know, it would make you :sick:

davereid

4th September 2008, 18:56

notme

4th September 2008, 19:26

I prefer Atmel AVR but 6 of one, half a dozen of the other. Think of the possibilities once you have a thinking engine in the battery loop - all micro's worth thier salt have EEPROM nowadays so you can easily store profiles, battery characteristics, user prefs etc.

A smart charge controller could also allow the engine to be started with no alternator load on it, and only start chargin the batt after say 10 secs of engine running....but i think the early warning of a failing batt or RR or alternator would be far more valuable - could save you boiling your battery, or not being able to start the bike when you want to come home at the end of the day or whatever.

I have made a start on this sort of idea - my last few bike have had a small micro powered voltage monitor on the dash, it's just a bicolour LED that indicates low/normal/high electrical system. If it ever indicates anyhting other than green (apart from brief transients) I will know about it and save myself a boiled battery or a dead bike! Never mind burnt out wiring and so on.

CookMySock

4th September 2008, 19:43

At redline, it seems the open-circuit voltage from the stator will be as high as 400-500 volts. Search for "open circuit" on <a href="http://www.fireblades.org/forums/general-discussion/58959-electrical-help.html">this</a> page. So be careful using anything but a shunt regulator. This is impossibly high for an economical series or switching regulator. Note his "fingertips" comment as well.

Steve

k14

4th September 2008, 20:05

It's a simple DC/DC converter. Looks like it's a step down (buck type) only, and it's probably not isolated.

So how you build one is you get a switch, inductor, and a diode and control them in the right way. :shifty:

Rather than designing and building one - since this is a specialized application I would look for a cheaper version of the same thing. It's amazing how much of a price premium people will charge for a "compact electrochemical energy conversion device" just because most people don't know that all they are getting is an AA battery.....

In the same manner, this "RS125 voltage regulator" is a generic DC/DC converter, much like the ones linked below that are a weeeeee bit cheaper:

http://www.jaycar.co.nz/productView.asp?ID=AA0218&CATID=&keywords=converter&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

Oh and the material cost of even the jaycar one? You don't want to know, it would make you :sick:
You sure that is exactly the same? The thing that makes me think the jaycar unit is slightly different is because it says it needs a heatsink. To me that implies it is inefficient, which is the very reason for having the unit in the first place. I run my bike now with no voltage regulator and just straight off the batteries (14v down to 12.6ish) so would be worse off with the jaycar unit. Or do I have my wires crossed??

notme

4th September 2008, 20:11

You sure that is exactly the same? The thing that makes me think the jaycar unit is slightly different is because it says it needs a heatsink. To me that implies it is inefficient, which is the very reason for having the unit in the first place. I run my bike now with no voltage regulator and just straight off the batteries (14v down to 12.6ish) so would be worse off with the jaycar unit. Or do I have my wires crossed??

wires crossed....good one.....:-)

The jaycar one will achieve the same thing as the unit in your link. The one in your link most likely needs a heatsink but it isn't mentioned, or the mounting instructions will be very specific about mounting it to the frame (i.e. a heatsink....)

Plus the jaycar one mentions that it only needs a heatsink for very high transformation ratios - i.e. if you wanted full current out of it at 12V output with a 30V input or similar.

Any switching bypass regulator is going to be bazillions of percent (excuse the tech speak) better than a series shunt regulator.

A swithcing regulator only lets through the energy required, wheras a shunt regulator wastes all the energy that is not required as heat.

notme

4th September 2008, 20:34

At redline, it seems the open-circuit voltage from the stator will be as high as 400-500 volts. Search for "open circuit" on this (http://www.fireblades.org/forums/general-discussion/58959-electrical-help.html) page. So be careful using anything but a shunt regulator. This is impossibly high for an economical series or switching regulator. Note his "fingertips" comment as well.

Steve

Sigh. I'll take this one Dave but you get to answer the next one :-)

Steve - the link you gave is some guy posting his opinion on a forum. Not much different to what I'm doing right now you reckon?

Well, he has several errors in his statements, feel free to check what i am telling you against any references you like as long as they are "official" i.e. textbooks, other qualified people etc.

Oh, and also please bear in mind dude, I'm only interested in the correct information getting out there for everyone's understanding - not meaning to call you a liar or say I'm smarter than you or any such horseshit!

Here's what he says in his post and the issues with it:

"The stator (or generator, but its not an alternator) has an open circuit voltage around 45 volts. If you redline the engine, you will be testing the stator's insulation with about 500 volts. That can blow your fingertips off if you touch it. The voltage from any two phases should be the same. When you hook it up to the regulator/rectifier, it will clamp all three down to about battery volts. Its a shunt type regulator. That means the power you don't use is shorted to the coil."

1. He seems to be saying that the spinny thing that generates power in your bike is called a stator or a generator, not an alternator.
WRONG. A stator is an internal part of an alternator. A generator produces DC from a mechanical input. The thing in your bike that the engine turns to make power is an ALTERNATOR. Note - there is a shitload of complexity behind this, and if you really want to get into it an alternator can be dubbed a form of a synchronous, single source fed generator, but let's not get into that. For all intents and purposes, to 99% of people the thing on your bike is an alternator simply by virtue of the fact that it produces alternating current.

2. His comments about 500 volts.... You can measure the raw alternator output many ways, and get many readings. A common mistake is measuring the phase to phase voltage and going oh my god it's several hundred volts! The correct readings will be in the order of 80 volts, and even so this means nothing, load it down a bit and the voltage will drop.

500 volts from a bike alternator (humoring the guy for a moment) will not "blow your fingers off. Ever had a static shock? Well guess what - you might have had as much as 50,000 volts across your finger during that shock !!!!!!!! OH NO!!!!! MY GOD WILL SOMEONE THINK OF THE CHILDREN!!!!!!.

yeah.

I am far more worried in my day to day work about the "mere" 48volts that the battery banks i test my new designs on hold......talk about blow your fingers off - people have had big spanners vaporized by those things! And then later that day I go and accidentally stick my fingers across a 450volt PFC bus, go "ow, fukme!" and get on with it.

There's more to it than voltage, and the simple fact of the matter is that 500 volts is nothing to modern power hardware.

3. The power you don't use is shorted to the coil huh? OK.....which coil is this? There are many coils in your alternator......

In a shunt regulator the power that you don't use to supply the load (your battery and lights and so on) is shorted to ground and DISSIPATED partly in the alternator coils, partly in the power semiconductors inside your regulator/rectifier, partly in the wiring joining it all up, and so on. Hell, some of it is even dissipated into various magnetic and electric fields!

So - a shunt regulator is the cheapest way to tackle a typical bike electrical system's requirements, but it is DEFINITLEY the nastiest as well.

A series reg is much nicer but - and here's the reason it is unusual for a bike to have one - it costs the manufacturer more to put in.

HTH your understanding :rockon:

notme

4th September 2008, 20:49

You sure that is exactly the same? The thing that makes me think the jaycar unit is slightly different is because it says it needs a heatsink. To me that implies it is inefficient, which is the very reason for having the unit in the first place. I run my bike now with no voltage regulator and just straight off the batteries (14v down to 12.6ish) so would be worse off with the jaycar unit. Or do I have my wires crossed??

Forgot to mention on other point - if you are happily running your bike off the battery directly, then don't introduce another loss!

The point of the reg is to....well....regulate.... :-) so the only downside of not having one is that your bulbs and ECU and coils and other electrics are exposed to a varying voltage as the battery runs down rather than a constant 12V or so. Bulbs may burn out sooner than they otherwise would (you might not even notice the reduction in life) and the coils will be ok - the thing I'd be worried about is the ECU or any other sensitive electronics.

If you've been running it battery - only for a few days and it seems fine, i'd suggest that the damage just hasn't shown up yet. If you've been doing this for a year or something then obviously everything is holding up fine!

Warr

5th September 2008, 00:15

.....is a generic DC/DC converter, much like the ones linked below that are a weeeeee bit cheaper:

http://www.jaycar.co.nz/productView.asp?ID=AA0218&CATID=&keywords=converter&SPECIAL=&form=KEYWORD&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=

Allun great input to a problem way too many of us have encounted with todays bikes. If the manufactures had spent a few more $'s on proper alternators with slip rings and a controllable stator magnet we wouldnt be having this conversation! Sadly slip rings dont work so well in an oil-filled enviroment

But .. to my point... is the heart of the Jaycar box likely to be a LM317 or similar?

notme

5th September 2008, 07:50

Allun great input to a problem way too many of us have encounted with todays bikes. If the manufactures had spent a few more $'s on proper alternators with slip rings and a controllable stator magnet we wouldnt be having this conversation! Sadly slip rings dont work so well in an oil-filled enviroment

But .. to my point... is the heart of the Jaycar box likely to be a LM317 or similar?

The jaycar box is a rebranded Kemo unit, from the specs it has to be a simple switchmode unit.

There are heaps of similar things out there, the Jackoff unit was just the first google found for me that matched the specs i searched for :-)

If it was me, I'd probably go for something a bit higher in quality because automotive environments are harsh on electronics, but there's no need to go up to the extremes of that european unit that was mentioned....or to fit a reg at all if the application doesn't demand it!

You're right - if bikes had car style charging systems they would be a buttload more reliable, but in the interests of cost, weight, complexity you just don't see it very often.

xwhatsit

5th September 2008, 13:11

Woot! I'd like to see this microcontroller version -- at least I can understand software :laugh:

Now with the Great KB Shunt Regulator v1.0 (GKBSR 1.0), forgive me, I'm not too bright -- upstream of this we build the little wee rectifier you described in the other thread. I've got three wires coming from my alternator, three phase. These are... combined? Just join the wires together or summat? And then the two `Off-page connectors' listed there, this being rectified sort-of-DC by now, the top one is the positive rectifier output and the bottom one is the negative rectifier output but we connect it straight to earth?

Sorry. I'm sure my questions reflect a profound lack of knowledge in these things :D

CookMySock

5th September 2008, 14:33

HTH your understanding :rockon:Yeah I mainly wanted to refer to the open-circuit voltage possibly being impractical, but after further reading I think I am wrong here. Even if it was 500V, many common SCRs will handle that. I still think his comment about hitting the limits of stator insulation are possibly an issue. Stators are designed to have their outputs clamped by the regulator, not run (almost) free at (near) their terminal voltage - the difference is several orders of magnitude. We shall see.

For the microcontroller operated version, further reading material here ;
http://services.eng.uts.edu.au/~venkat/pe_html/pe05_nc6.htm
edit:better link

The SCRs might be a bit noisy though, and the uC will have to follow the three stator outputs. Overkill ?

cheers,
Steve

notme

5th September 2008, 17:20

Overkill would be:

- Full wave synchronous rectifier bridge
- Complete microprocessor control, monitoring alternator, battery, and internals (temp, faults etc)
- Preemptive fault notification - e.g. an error code that tells you your battery is going to fail soon, not just that it has (which is still a step up from the systems we currently have!)
- Efficiency improvement and size reduction

As for the stator insulation issue - the manufacturer will design the alternator for worst case isolation i.e. the RR fails open and the bike is at full revs. It's part of compliance testing of any consumer product to think of and test for scenarios like that. It even gets to the point of stupidity at times - that's how anal the testing agencies are.

Many years ago my father was importing a line of electric lawnmowers into the country, and the testing agencies here had a complaint re the safety of the units. The complaint was that a person could potentially get a shock if the lawnmower's electric motor developed a short circuit that led to the shaft becoming live, because the blades are metal and bolted to the shaft.

Now if someone touches the blades, they will get a shock. Since the only real scenario where this could happen also involved the motor not stalling and blowing the fuse (hence removing the shock hazard), dad deduced that the mower had a built in safety feature that would stop people getting a shock - thier fingers would be cut off by the spinning blades!
Needless to say, the testers didn't go for it, and the mowers were allowed in to the country only if they had a plastic joiner between blade and motor shaft. So the mowers gained a reputation for throwing blades off when they hit the tiniest obstacle in the grass, and never sold well, and were not re imported after the initial shipment.

Point is, you can be sure that mr Honda or mr Suzuki was made to go through the same hoops and all possible scenarios, no matter how stupidly inconceivable, will have been thought out - so i doubt that the insulation on a stator is going to pose a problem. :Punk:

davereid

5th September 2008, 19:21

Now with the Great KB Shunt Regulator v1.0 (GKBSR 1.0), forgive me, I'm not too bright -- upstream of this we build the little wee rectifier you described in the other thread. I've got three wires coming from my alternator, three phase. These are... combined? Just join the wires together or summat? And then the two `Off-page connectors' listed there, this being rectified sort-of-DC by now, the top one is the positive rectifier output and the bottom one is the negative rectifier output but we connect it straight to earth?

Yeppers...

If you built the rectifier in the other thread, and wired your alternator into it, then you could connect its output, into the GKBSR 1.0.

This would give you a working RR, for under $40, that would work on virtually any bike.

In electronics the "rule of 99" applies. That is, the first 1% of the design gives you 99% of the desired outcome.

GKBSR 1.0 needs to be built to test it. But its a 10mm bolt for a 6mm load. Its almost certain to be reliable and tough, as long as it is given a decent heatsink to get rid of the heat.

I'll tart up the schematic to show the rectifier, and outline the problems for constructors if I have some free time next week.

Then we will start on a micro based one.

davereid

5th September 2008, 19:34

...Stators are designed to have their outputs clamped by the regulator, not run (almost) free at (near) their terminal voltage - the difference is several orders of magnitude. We shall see...cheers,
Steve

Hi Steve,

You have made a good point.

Manufacturers have lots to consider when making a stator.

You could use really strong magnets, but a few turns of very thick wire.

A "short fat" stator.

It will have a flat output curve, delivering lots of amps, with output voltage really dependant on rpm as it has a low internal resistance. This would be great for direct lighting coils, as at idle you would get enough to get lights going, and at 5000 rpm, you would have everything well lit up. This kind of stator would be hard to regulate with a shunt regulator. It would just keep on moving electrons and melt !

Or you could make a "tall thin" stator. Lots of turns of a finer wire.
Higer terminal voltages allow battery charging at lower rpm. Higher internal resistances mean its easy to regulate with a shunt regulator. And high rpm is not a problem. But, most of the time you are wasting energy, as you have to regulate this beast as terminal voltage varys wildly with load as well as with rpm.

These can produce quite high terminal voltages at high rpm- no load. And often, its only the enamel paint that is your insulator !

Warr

12th September 2008, 16:50

A whole week and no word from the experts

A smart charge controller
All sounds good talking about it but is it possible.
At the moment any extra power is dissipated back into the stator coils by means of the SCR's firing and shorting out that phase.

The series regulator option is unworkable due to the power dissipation of the regulator.

The switched mode version sounds exciting .. where does the Pulse Width Modulated setup fit in ??

davereid

13th September 2008, 08:43

A whole week and no word from the experts

All sounds good talking about it but is it possible.
At the moment any extra power is dissipated back into the stator coils by means of the SCR's firing and shorting out that phase.

The series regulator option is unworkable due to the power dissipation of the regulator.

The switched mode version sounds exciting .. where does the Pulse Width Modulated setup fit in ??

I sort of felt there was no interest in this project as the thread was very quiet.

And maybe the shunt regulator meets everyones needs, as it quite capable of handling most bikes, indeed its all we ever used for the first 100 years of motorcyclng !

But if there is a real interest, I'll design a PWM system. My preference is using analog electronics, so anyone who wants to build the system need merely purchase the components, and no software needs to be obtained, and no micros programmed.

As I stated right at the beginning, it needs others to come on-board to build them and test them.

pete376403

13th September 2008, 11:20

Hey I'm keen - I've got a mid 80s Suzuki with a charging circuit that makes Lucas stuff look good.
I can't design electronics at all but I can follow circuits and build stuff.

Looking forward to a design I can make and try

Warr

13th September 2008, 11:50

Will put my hand up also to prototype designs with merit !!

birdhandler

13th September 2008, 13:41

count me in as well

Ixion

13th September 2008, 14:17

I'll build and test.

Squiggles

13th September 2008, 18:20

Ill give it a go as well

Warr

14th September 2008, 00:24

Here is a commercial switched mode system
http://www.hotbikeweb.com/tech/0608_hbkp_compu_fire_charging_system/index.html

davereid

14th September 2008, 10:39

OK, I'll design something today, should have something on-line for the builders today or tomorrow.

davereid

14th September 2008, 16:07

OK... attached a circuit diagram, and the manual for the IC.

Warr

14th September 2008, 17:28

Sweet.Will likely find a diode array out or a tired car alternator ...
What frequency have you set it to run at...
How come no inductor in output ??

davereid

14th September 2008, 18:19

It should run about 2khz.

No inductor required as we are are not filtering the output, the battery can do that for us, so we can use a slower oscillator than might otherwise be selected. This is kind on our transistors, and might help constructors, as they should be able to hear it grunt up.

The error amplifiers have been turned into comparators with hysteresis, this is also to reduce the workload. The result should be a system which switches in-and-out, commencing charging whe the battery drops below 12.6 volts, and charging up to 14 before reducing charge current.

The current limiting should be set to avoid damaging the output transistors. By default it will also stop the battery loading the charging system while cranking.

pete376403

14th September 2008, 20:32

Would veroboard tracks be adequate for this?

davereid

14th September 2008, 20:38

Would veroboard tracks be adequate for this?

Yep, for everything except the transistors and rectifier.

DB pointed out that if you were to turn the key off, while coasting in gear, the regulator would lose its feedback, and would stop regulating.

It may not do any harm, as the current limit would still work, and the bike will soon stop, but well spotted Steve.

No doubt a few more bugs in there yet !

I suggest as a fix, pin 12 of TL494 be connected to the battery via the IGN SW instead of to the rectifier output.

Warr

14th September 2008, 21:14

It should run about 2khz.

No inductor required as we are are not filtering the output, the battery can do that for us, so we can use a slower oscillator than might otherwise be selected. This is kind on our transistors, and might help constructors, as they should be able to hear it grunt up.
Could this be asking too much of the battery. My thoughts are for the solid state ignition systems we all run. I realise a suitable inductor may not be a straight-forward bit of kit to buy but would be relatively easy to build.
... I'm no expert but just asking tis all. :)

.......
The current limiting should be set to avoid damaging the output transistors. By default it will also stop the battery loading the charging system while cranking.
What max charge current would you suggest ?

Do we know what the input voltage would rise to when the regulator is in "off mode" ? Will the 1000uF input capacitor be high enough rated at 63volts ?

notme

15th September 2008, 07:34

Could this be asking too much of the battery. My thoughts are for the solid state ignition systems we all run. I realise a suitable inductor may not be a straight-forward bit of kit to buy but would be relatively easy to build.
... I'm no expert but just asking tis all. :)

What max charge current would you suggest ?

Do we know what the input voltage would rise to when the regulator is in "off mode" ? Will the 1000uF input capacitor be high enough rated at 63volts ?

Your battery is already doing this job in your current charging system - it wll be fine. It's just doing what it does in it's function as an energy storage device.

Max charge current will be a hard one to specify as it depends on your consruction i.e. heatsinking and mounting, and your bike's electrics and battery size. You probably want to measure your bike's current draw at full load (all electrics on, headlights on high etc) at idle and at a few points in the rev range, and go from there. You want the current limit to be higher than the max current that the bike wants at any time.

Also - check the diodes you use for the rectifier bridge, 50Hz ones are probably a bit slow as I think most multipole alternators spit out AC at up to a KHz or so - would need to check this for your bike though.

davereid

15th September 2008, 07:47

jonbuoy

15th September 2008, 07:52

Standard bridge rectifier diodes will be sweet - Also as its an AC generator won't the output voltage from the stator stay the same regardless of engine RPM - only the frequency of the cycles will increase?

Edit: Also on the circuit you've got up, the voltage at the input to the controller could be higher than 42VDC - the guys on the blade forum measured 45VAC off load on the stator -that will be even higher when its rectified into DC. And it will surely be messy, maybe you could take the supply further down from the battery itself? I don't think its going to work very well - it would be fine if the output of the rectifier was proper DC but it won't be if you scope it'll still look pretty messy - a big cap might help but then its a pain to fit.

pete376403

15th September 2008, 11:21

davereid

15th September 2008, 17:22

Not sure if this is relevant, but the test process for GS Suzuki stator says the stator is bad if the voltage between any pair of stator leads is less than 60V AC at 5000 RPM.
I know on my bike I've seen about 75VAC when doing this test.

http://thegsresources.com/garage/gs_statorfault.htm

Good link.. a couple of minor mods required to handle the extra voltage, and jonbuoys concern about the power supply uses the same fix as DBs question.

I'll re-draw and re-post the diagram with the mods done.

Beer required first.. !

davereid

15th September 2008, 17:55

OK, revised as follows..

Power supply (and soft start circuit) now also switched and supplied via keyswitch.

MJE340 transistor added to allow 100-140 volts plus voltages.

Capacitor upgraded to 100v - or just use the voltage you need.

notme

15th September 2008, 18:30

Standard bridge rectifier diodes will be sweet

Diodes - standard (i.e. slow) diodes will not be OK on a high frequency system, unless you don't mind wasting power in them.

Also as its an AC generator won't the output voltage from the stator stay the same regardless of engine RPM - only the frequency of the cycles will increase?

The type of alternator in most bikes is a low rpm permanent magnet alternator - unlike a high rpm car one with an adjustable stator field.

What this means is that as the engine RPM changes, the output frequency and power of the alternator changes with it. It's actually a fine balance between having enough charging power at idle to ensure that with ful load you don't run out of juice if you sit idling for 15 mins and making sure you don't generate a bazillion watts of power at high rpm. All of this is solved with a car style alternator but as previously mentioned the complexity and costs are keeping them out of bikes at the moment.

So the voltage AND the frequency of the ripple on the alternator output will vary with engine RPM and load.

Edit: Also on the circuit you've got up, the voltage at the input to the controller could be higher than 42VDC - the guys on the blade forum measured 45VAC off load on the stator -that will be even higher when its rectified into DC. And it will surely be messy, maybe you could take the supply further down from the battery itself?

Not sure what you mean here? You could take the supply for the chip from the battery, but then if the battery is flat the chip will not enable the charging system e.g. if you push start the bike. Also unless you add more complexity with a shutdown circuit the chip will draw power from the batttery while the bike is off. It could all be done, but Dave has designed in a nice simple solution and the cap size given will be plenty, as the chip is not drawing huge amounts of current.

I don't think its going to work very well - it would be fine if the output of the rectifier was proper DC but it won't be if you scope it'll still look pretty messy - a big cap might help but then its a pain to fit.

You might be surprised how close to "DC" the output is! It's not battery like, but it's not exactly swinging up and down by 30V. Older style mains powered automotive battery chargers used to just have thyristors that would allow continuous pulses of rectified AC going from 0 to ~14V to charge a battery.

HTH :done:

EDIT: Dave has been drawing while I composed my thoughts - chip power supply issue fixed! :-) Another potential improvement is to filter the chip suppl via some series impedance, meaning the cap will have more effect.

Ixion

15th September 2008, 18:46

Hm. Will this work on single phase alternators (with two less rectifier diodes of course)? Most of my bikes are so old that multiphase hadn't been invented.

davereid

15th September 2008, 18:50

Hm. Will this work on single phase alternators (with two less rectifier diodes of course)? Most of my bikes are so old that multiphase hadn't been invented.

Yes, it should be fine. you could even run it off a 24 volt battery if you wanted to do so for testing purposes.

pete376403

15th September 2008, 21:40

Couple of questions, please.
Looking at this http://www.farnell.com/datasheets/99091.pdf the Vishay 36MT has a number of voltage codes from 10 thru 160. Which one should we be using?
Also the wattage of the resistors?

Any other component values to be aware of?

Sorry if this is basic electronics but as I said before I haven't a clue about designing circuits

jonbuoy

16th September 2008, 03:33

Diodes - standard (i.e. slow) diodes will not be OK on a high frequency system, unless you don't mind wasting power in them.

I'm using them now - and I'm not the only one no problems/huge losses.

The type of alternator in most bikes is a low rpm permanent magnet alternator - unlike a high rpm car one with an adjustable stator field.

What this means is that as the engine RPM changes, the output frequency and power of the alternator changes with it. It's actually a fine balance between having enough charging power at idle to ensure that with ful load you don't run out of juice if you sit idling for 15 mins and making sure you don't generate a bazillion watts of power at high rpm. All of this is solved with a car style alternator but as previously mentioned the complexity and costs are keeping them out of bikes at the moment.

So the voltage AND the frequency of the ripple on the alternator output will vary with engine RPM and load.

I have one with a variable field coil on my 750, frequency of the ripple? You mean the frequency of the AC sinewave? Which will affect the ripple coming from the rectifier diodes.

Not sure what you mean here? You could take the supply for the chip from the battery, but then if the battery is flat the chip will not enable the charging system e.g. if you push start the bike. Also unless you add more complexity with a shutdown circuit the chip will draw power from the batttery while the bike is off. It could all be done, but Dave has designed in a nice simple solution and the cap size given will be plenty, as the chip is not drawing huge amounts of current.

Look at the diagram - Your trying to smooth the entire output of the rectifier not just the supply to the IC, with that one wee cap.

You might be surprised how close to "DC" the output is! It's not battery like, but it's not exactly swinging up and down by 30V. Older style mains powered automotive battery chargers used to just have thyristors that would allow continuous pulses of rectified AC going from 0 to ~14V to charge a battery.

Stick a scope on it and see how close to DC it is.

HTH :done:

EDIT: Dave has been drawing while I composed my thoughts - chip power supply issue fixed! :-) Another potential improvement is to filter the chip suppl via some series impedance, meaning the cap will have more effect.

Anywhoo good luck with the project, be interesting to see how it works out.

davereid

16th September 2008, 07:27

...the Vishay 36MT has a number of voltage codes from 10 thru 160. Which one should we be using?
Also the wattage of the resistors?

Any other component values to be aware of?

A voltage code of 20 or greater will be fine.

All resistors can be bog-standard 1/2 or even 1/4 watt resistors, with the exception of the 300 ohm resistor.

This resistor is only ever carrying current when the output transistor is on. So it will have the battery voltage plus any losses across the transistor. Say a max of 16 volts. This means a 1 watt resistor should suffice.

But, I would suggest a 5 watt resistor here, as it will (or a few nanoseconds !) carry a much higher load as the transistors switch.

The TIP41C should be selected.. 41A/B has a lower voltage rating.

notme

16th September 2008, 07:56

Anywhoo good luck with the project, be interesting to see how it works out.

Can't work out how to easily quote the quote of a quote.....but anyway to address your concerns:

The rectifier diodes - my point is, using diodes that are too slow for the AC you are rectifiying will be lossy. I don't know for sure the frequency of the AC from most bike alternators, but it's something to be aware of for the constructors if the rectifier starts overheating and popping. If it doesn't, there's no problem.

Regarding the voltage and frequency changes in the alternator output - I'm not sure of your understanding here, and I'm only trying to help clear it up. I am talking about a permanent magnet, low RPM type alternator like on most bikes. If you have a wound field alternator (like a car) on your bike, then non of that applies. In that case, the voltage will be regulated by the alternator, the frequency of the ripple will change with RPM, and all of the info in this thread is useless to you because the RR we are talking about won't work on your system.

With the smoothing cap - my mistake - I have seen so any similar circuit diagrams that I "saw" a resistor where there wasn't one. If there was a filter resistor in the feed path to the chip then the cap is isolated by that resistor and the chip will be the only thing drawing on it. Dave has changed the circuit now so that doesn't apply, as the chip has a much better filter, the battery.

Finally, regarding what comes out of the alternator being DC - and again I am talking about the alternators on most bikes nowadays, so that precludes Ixion's older single phase jobbie - what comes out is pretty much DC, it just depends on your definition. Is DC 100% oure zero ripple? In that case, you will only ever have DC from an electrochemical reaction such as in a battery. The "DC" that comes out of telecoms rectifiers is allowed by the various standards to have around 20mV ripple on it. Is that still DC? The "DC" out of your alternator will have as a generalisation something like a volt of ripple.

One volt out of 14 means about 7% ripple.....and to sum it up:

- true sinewave AC goes below zero the same amount as it goes above zero

- rectified AC goes to zero but not below, i.e. the negative halves of the cycle have been flipped upside down

- DC is a steady voltage that does not vary cyclicly. The disclaimer on that last statement is that most people realise that almost all DC has some ripple on it, if it's not an appreciable fraction of the total magnitude then we just call it DC.

I could scrible some diagrams if that would help, hopefully the descriptions are clear enough though?

davereid

16th September 2008, 08:08

Anywhoo good luck with the project, be interesting to see how it works out.

Thanks jonbuoy...
I'm interested in some of your comments...

This is a community project, and I cheerfully confess to this being my first power supply design venture.

So your design assistance is welcomed !

Diodes - standard (i.e. slow) diodes will not be OK on a high frequency system, unless you don't mind wasting power in them.
I'm using them now - and I'm not the only one no problems/huge losses.

What kind of losses do you consider huge ?

I looked at this and thought the losses could be tolerated. In fact, to a certain degree I need to find about 0.5 - 1.5 ohm or equivalent in losses in the stator, wiring and rectifier or the circuit would need a ballast resistor.

As the losses will increase with frequency (rpm) as will output, this was exactly the characteristic I wanted. But Vishay don't publish reverse recovery time data, so I just treated it as being typical of 35 amp rectifier diodes.

Can you suggest a better product that all constructors will be able to access ?

I have one with a variable field coil on my 750, frequency of the ripple? You mean the frequency of the AC sinewave? Which will affect the ripple coming from the rectifier diodes.

This is a 3 phase, full wave rectifier. The ripple will be at 6 times the alternator frequency, so I thought it would be pretty negligible.

Have I F'd up here ?

Look at the diagram - Your trying to smooth the entire output of the rectifier not just the supply to the IC, with that one wee cap.

With the original diagram, with the output transistors OFF, the only thing being supplied by the capacitor was the IC, so I figured it was adequate. Once the output transistors came on, the battery did the levelling.

In the new design, the battery does the job of power supply the entire time, so its pretty irrelevant.

CookMySock

16th September 2008, 08:26

Slow diodes are only a problem in high frequency power circuits, when they spend a lot of time partly switched on or off, thereby increasing their dissapation. I don't think this is important here, unless you are rectifying 200kHz.

Yeah he is kinda right about the cap smoothing the entire output of the rectifier. It probably wont last long or do a good job - put a low value resistor in the supply line before it, just for the supply to the chip. I don't think the cap will do jack anyway, as most of these chips have really good regulation, and you can supply them with a crappy supply of any sort and they will make it turn to gold for you.

Interesting !

So who has built one? Can anyone design a PCB for it ?

Steve

jonbuoy

16th September 2008, 08:39

With the original diagram, with the output transistors OFF, the only thing being supplied by the capacitor was the IC, so I figured it was adequate. Once the output transistors came on, the battery did the levelling.

In the new design, the battery does the job of power supply the entire time, so its pretty irrelevant.[/QUOTE]

Cheers Dave - haven't been trying to piss in anyones cornflakes on this - just putting my oar in :niceone: I've never done a comparision back to back with schottkys or the like - I replaced the originals with two square pack rectifiers - nothing got hot battery charged as well as it ever did so I thought the job done. Originally the bike had a relay regulator to control the rotor voltage I looked at a few circuits then found an single chip alternator regulator in a three pin package that looks like it'll do the trick, they are obsolete so I need to put in an order with Dial Electronics. I did do some frequency measurements on my firestorm when I had reg and stator fail - I don't remember what frequency it was running at, stator voltage was 26VAC at idle or flat out so I can only assume it was being clamped by the rect.

I suspect every bike will be a bit different in voltage and frequency so a universal one would be handy. I can't help thinking noise and ripple are going to be the biggest headaches.

Warr

16th September 2008, 11:15

Originally I had thought of using a diode array out of a car alternator.. But last night had decided to just use 2x 35A 400V Bridge rectifers from JayCar, only $5 each. And this would give me a spare phase should 1 die!!
Then this morning reading about the frequency issue?? is it??. So I started searching for someone in NZ who supplied 3 phase Rectifiers. **

Came across this site, for them that want to see how it all works check out the simulation. Dont worry that they are SCR's, with "Firing Angle" =0 they are diodes.
http://services.eng.uts.edu.au/~venkat/pe_html/ch05s1/ch05s1p1.htm#simulation

edit - Link not working now :( Cant access site....

** Still didnt find anyone yet.

davereid

16th September 2008, 17:19

DB might be on to it with regard to rectifiers.
We will only be running at 10k-15k max.. audio frequencies, unlikely to be an issue. If we were trying to do things at 500k, maybe we would have a problem, but for $10 just try your cheapo pair of jaycar rectifiers.

notme

16th September 2008, 17:30

Thanks jonbuoy...
I'm interested in some of your comments...

This is a community project, and I cheerfully confess to this being my first power supply design venture.

So your design assistance is welcomed !

Diodes - standard (i.e. slow) diodes will not be OK on a high frequency system, unless you don't mind wasting power in them.
I'm using them now - and I'm not the only one no problems/huge losses.

What kind of losses do you consider huge ?

I looked at this and thought the losses could be tolerated. In fact, to a certain degree I need to find about 0.5 - 1.5 ohm or equivalent in losses in the stator, wiring and rectifier or the circuit would need a ballast resistor.

As the losses will increase with frequency (rpm) as will output, this was exactly the characteristic I wanted. But Vishay don't publish reverse recovery time data, so I just treated it as being typical of 35 amp rectifier diodes.

Can you suggest a better product that all constructors will be able to access ?

I have one with a variable field coil on my 750, frequency of the ripple? You mean the frequency of the AC sinewave? Which will affect the ripple coming from the rectifier diodes.

This is a 3 phase, full wave rectifier. The ripple will be at 6 times the alternator frequency, so I thought it would be pretty negligible.

Have I F'd up here ?

Look at the diagram - Your trying to smooth the entire output of the rectifier not just the supply to the IC, with that one wee cap.

With the original diagram, with the output transistors OFF, the only thing being supplied by the capacitor was the IC, so I figured it was adequate. Once the output transistors came on, the battery did the levelling.

In the new design, the battery does the job of power supply the entire time, so its pretty irrelevant.

Diodes - there are lots out there, such as an MUR1560 @ under $2 each for small quantities - or just choose any SCHOTTKY power diode. The power loss may not be an issue but that was one of the things that stuck out when I was reviewing the design (too many design review sessions at work i suppose). The first constructor will have the answer for us no doubt :-) .