Voltage regulators

bluemax said:
Interesting post.
A couple of things to comment on that explains how the zener system works on our Nortons and why lithium batteries may need special consideration

The Alternator (dynamo/magneto coil) is a current limited system due to the design and magnetic flux available.
These coils are designed to run constantly at the maximum design current and this is done in the basis zener regulator by the zener presenting a load to the coil/rectifier by shunting the coil to earth. The coil voltage then drops as the current is shunted as the coils have limited current avbl the voltage will drop until it goes below the zener conduction voltage and the zener stops conducting and the voltage rises, then the zener conducts again and loads the coil again. This results in a constant voltage determined by the zener. When a load is presented the current is shared by the zener and the load. But the total current is fairly constant. Zener regulator are normally designed so that the zener should still conduct about 10% of the total current available at the maximum load so as to keep it in conduction and thus regulates the voltage. In fact for most systems that use low resistance sources like a battery or large transformers they must have a series resistor to stop the zener drawing mega current and destroying itself. The resistor is calculated to keep the zener in conduction at max load hence the +10%.

The Norton system uses the coils ability to supply only a certain maximum current as the effective limiting resistance.

Now the coil is happy to be completely shorted to earth as it will only ever supply a limited current, not like shorting a battery as they have a very low internal resistance.

The coils will get no hotter then when running a normal load or completely shorted and in fact they will be cooler as the application of ohms law will show that power is current x voltage and if the voltage is 0v then current will be irrelevant as the the power will always be 0.

The difference as I see it with a zener V say a podtronics is that the zener does its regulation at a DC level after being rectified by the bridge where as the podtronics do it at an AC level in one leg of the bridge rectifier. The podtronics should run cooler in comparison.

The zener regulator or Podtronics are designed to charge a lead acid battery and the zener conduction point is designed to suit a lead acid battery. So I'm guessing using a lithium battery that has a higher terminal voltage will probably dump a high current through the zener or podtronics as they will try and conduct at the normal charging voltage and as the lithium battery is happy to deliver current at the higher voltage then it will most likely let the smoke out of the standard regulators or blow the fuse or both, or be very close to doing same.

That is how I see but I am quite happy to be proven wrong.

Cheers
Peter R
Click to expand...

I always assumed a Podtronics or similar unit was more or less a combination rectifier/zener, and if it is, it's entirely possible the current from the alternator is rectified before being fed into the system and that a built-in zener (or other diode) shunts off any excess. Just one self-contained unit with it's own heat sink rather than 2 separate pieces.
 
Danno said:
I always assumed a Podtronics or similar unit was more or less a combination rectifier/zener, and if it is, it's entirely possible the current from the alternator is rectified before being fed into the system and that a built-in zener (or other diode) shunts off any excess. Just one self-contained unit with it's own heat sink rather than 2 separate pieces.
Click to expand...

I thought the Podtronic and other similar rectifier/regulator was a better design, but it is not, at least the way I see things. As I mentionned, this is the first time I have seen any regulator working like that. A mechanical analogy to the Podtronic and its siblings would be an vehicule without a throttle with the speed regulated by applying the brakes, that doesn't make sense now does it?

Jean
 
bluemax said:
Interesting post.
A couple of things to comment on that explains how the zener system works on our Nortons and why lithium batteries may need special consideration

The Alternator (dynamo/magneto coil) is a current limited system due to the design and magnetic flux available.
These coils are designed to run constantly at the maximum design current and this is done in the basis zener regulator by the zener presenting a load to the coil/rectifier by shunting the coil to earth. The coil voltage then drops as the current is shunted as the coils have limited current avbl the voltage will drop until it goes below the zener conduction voltage and the zener stops conducting and the voltage rises, then the zener conducts again and loads the coil again. This results in a constant voltage determined by the zener. When a load is presented the current is shared by the zener and the load. But the total current is fairly constant. Zener regulator are normally designed so that the zener should still conduct about 10% of the total current available at the maximum load so as to keep it in conduction and thus regulates the voltage. In fact for most systems that use low resistance sources like a battery or large transformers they must have a series resistor to stop the zener drawing mega current and destroying itself. The resistor is calculated to keep the zener in conduction at max load hence the +10%.

The Norton system uses the coils ability to supply only a certain maximum current as the effective limiting resistance.

Now the coil is happy to be completely shorted to earth as it will only ever supply a limited current, not like shorting a battery as they have a very low internal resistance.

The coils will get no hotter then when running a normal load or completely shorted and in fact they will be cooler as the application of ohms law will show that power is current x voltage and if the voltage is 0v then current will be irrelevant as the the power will always be 0.

The difference as I see it with a zener V say a podtronics is that the zener does its regulation at a DC level after being rectified by the bridge where as the podtronics do it at an AC level in one leg of the bridge rectifier. The podtronics should run cooler in comparison.

The zener regulator or Podtronics are designed to charge a lead acid battery and the zener conduction point is designed to suit a lead acid battery. So I'm guessing using a lithium battery that has a higher terminal voltage will probably dump a high current through the zener or podtronics as they will try and conduct at the normal charging voltage and as the lithium battery is happy to deliver current at the higher voltage then it will most likely let the smoke out of the standard regulators or blow the fuse or both, or be very close to doing same.

That is how I see but I am quite happy to be proven wrong.

Cheers
Peter R
Click to expand...

I don't think that is how the permanent magnet alternator is designed to work, sure it CAN produce all the power it is designed for. For example, a 120 watt alternator CAN give 10 amps (120 watts / 12 volts = 10 amps), so a 120 watts load, or a 1.2 ohm resistor would let it work at its maximum. Let's say the load is doubled, then the alternator would try to maintain the voltage but it would fall for sure, but it would still be higher in current than what it was designed for, at that point, the wires would start heating up and the windings being the weakest link would start to cook, given enough time I would bet the alternator would be destroyed.

You must remember that the Zener will clip the top of the wave because it starts to conduct at a given voltage, the Podtronic type of regulator will short the inputs when the set voltage has been reached, this means not only clipping the top of the waveform, but more than 50% of the time the input is a dead short. As long as there is sufficient load, these regulators are just glorified rectifiers. If the load is reduced because for example you change the lightbulbs to LEDs, then the regulator will short the alternator for longer periods.

If you look at your bike's schematics, the fuses are from the battery to the load, there are no fuses on the AC side.

Jean
 
Jean,
Permanent magnet alternators are basic/simple in operation. They are not capable of maintaining any voltage level, they have no way of varying the magnetic flux as in the field winding of a car alternator. With no load (open circuit) they will produce a higher voltage at no current (no power produced) and at shorted input zero volts at maximum current be it limited by the available magnetic flux (again no power produced). There will be a sweet spot where the coils will produce the maximum designed power, somewhere between O/C and S/C. The zener will conduct at its designed voltage and effectively by its avalanche effect represent a short to the coil and rectifier. Equilibrium will be reached at the zener voltage and the current the zener draws at this point is the maximum design current. The whole system runs at full current all the time and the available current is shared by the load and the zener. This is probably why people report connector issues. Any connector resistance at this constant current will causes heating and melting over time irrespective of load levels.
The zener type regulator has full wave rectified A/C and is filtered by the capacitor if fitted and certainly by the battery applied to it to give a DC level. This DC is clamped by the zener to provide the regulated voltage. The zener will get warm when no load or light load and cooler with high loads.
The Podtronic type does the clamping or shorting of the coils in the legs of the bridge rectifier. In this configuration the Scr's would run cooler as they are not conducting all the time.

The point I was making about Lithium batteries was that they are capable of significant current at voltages above the zener clamping voltage and the system runs a risk of destroying the zener or electronic regulator as there is no limiting of this back current.

The whole system is a shunt regulator and by definition shunts the current to provide the required regulation voltage. The current is either shunted to ground or consumed by the load or both, but the current is always maximum. Properly designed coils and suitable wire thickness will have no issues running at maximum current.

Switching regulators are another kettle of fish and require unique switching design and snubbers to prevent back EMF when switching the coils out of circuit.

Cheers
Peter R
 
Voltage regulators


Here is a disembowelled regulator that is similar to the Podtronics type.
You can see two large diodes and the two SCR's on the circuit board. It has a small reference zener and associated circuitry to do the necessary scr switching.
This one is a dedicated negative earth version . The previous owner fitted this regulator to a positive earth bike.
It took me ages to figure out why I always got about 50k's from home and stranded on the side of the road with a flat battery.
Simple fix to get me home was to reverse the battery connection and bump start.

Peter R
 
marinatlas said:
Hi Peter thanks for that !
so do you think I had better to let my Mithium battery on the shelf (pity , as I have two of them , waiting my next project!!)........your thoughts are welcome, for me (at least!). Cheers Pierre.
Click to expand...

Mate this is just the way I see it.
You probably need to discuss with people that have fitted Lithium batteries to see what they have done or got away with. Maybe the fact the standard charge circuit does not fully charge the Lithium batter allows things to sneak through without issue. But if the battery is bench charged and then fitted to the bike it maybe marginal.
I don't run Lithium batteries so I can't give you the definitive answer.
You could go the linear regulator discussed in this post, that would work be it will run a bit warm due to the series transistor dissipating heat when regulating.

Something that just came to mind as I am writing this is I wonder if a forward biased diode was added in series with the zener which would in effect bump the regulation voltage by about another .7v, that might work but would depend on what the charge voltage for a lithium battery should be.
I will have to think about this some more

Cheers
Peter R
 
bluemax said:
Jean,
Permanent magnet alternators are basic/simple in operation. They are not capable of maintaining any voltage level, they have no way of varying the magnetic flux as in the field winding of a car alternator. With no load (open circuit) they will produce a higher voltage at no current (no power produced) and at shorted input zero volts at maximum current be it limited by the available magnetic flux (again no power produced). There will be a sweet spot where the coils will produce the maximum designed power, somewhere between O/C and S/C. The zener will conduct at its designed voltage and effectively by its avalanche effect represent a short to the coil and rectifier. Equilibrium will be reached at the zener voltage and the current the zener draws at this point is the maximum design current. The whole system runs at full current all the time and the available current is shared by the load and the zener. This is probably why people report connector issues. Any connector resistance at this constant current will causes heating and melting over time irrespective of load levels.
The zener type regulator has full wave rectified A/C and is filtered by the capacitor if fitted and certainly by the battery applied to it to give a DC level. This DC is clamped by the zener to provide the regulated voltage. The zener will get warm when no load or light load and cooler with high loads.
The Podtronic type does the clamping or shorting of the coils in the legs of the bridge rectifier. In this configuration the Scr's would run cooler as they are not conducting all the time.

The point I was making about Lithium batteries was that they are capable of significant current at voltages above the zener clamping voltage and the system runs a risk of destroying the zener or electronic regulator as there is no limiting of this back current.

The whole system is a shunt regulator and by definition shunts the current to provide the required regulation voltage. The current is either shunted to ground or consumed by the load or both, but the current is always maximum. Properly designed coils and suitable wire thickness will have no issues running at maximum current.

Switching regulators are another kettle of fish and require unique switching design and snubbers to prevent back EMF when switching the coils out of circuit.

Cheers
Peter R
Click to expand...

Peter, the magnetic field from permanent magnets or the one induced from another coil like in a transformer act the same way. If a transformer or an alternator is built to provide a certain power, they choose the number of turns for the voltage and size the wires to provide the current it is designed for. If I take a 250 watt transformer giving 12 volts, it can pump out 20 amps, the windings on the secondary are probably 12 ga and the primary 26 ga. If the primary is built with smaller wire and I short the output, the primary will most likely burn up, the same holds true for the secondary, if it is undersized and the output is shorted, then IT will burn up.

While it doesn't happen everyday, alternators do burn up and the most likely reason is a shorted output, this could happen if the rectifier blows and shorts out or the wires rub on a metalic piece and short out or a careless owner squeezes that cover tighter to stop an oil leak caused by the wires in the way, that does happen. If the alternator was designed to run with shorted outputs, all would be fine except they use the smallest wire they can get away within the designed power output, they know for sure there will be a load on it, light bulbs, ignitions, horn... they never thought a lazy regulator designer woul think of shorting the alternator as a means of regulation.

I have asked an alternator maker if running for a long time with shorted outputs is within the design parameters, I suspect it is not but I will surely take all the feet I have in my mouth out if it is so.

The thing with lithium batteries is that they will gladly let the voltage go higher than a lead acid battery, when they do that, they allow a Podtronic type of regulator to camp the input sooner in the cycle so the alternator spends more time with a shorted output than it does with a lead acid battery.

That's the way I see it

Jean
 
Here is my regulator potted up

Voltage regulators


I used regular old polyester resin I had left. I tried the regulator after it was all solid and it works fine.

Jean
 
I was told by an alternator maker that an alternator COULD be designed to run with a short circuit, but they are not. Alternators are designed to TOLERATE a short circuit for a certain period of time. Knowing that manufaturers tend to make things that are "just good enough" I wouldn't take a chance on long term teststing of an alternator designed for a Zener diode and slapping a rectifier regulator whose method of regulation is done by shorting the inputs.

With further interweb searches I found another option made by Shindengen http://www.shindengen.co.jp/product_e/e ... talog.html in Japan. Here are a few pictures of what they call "series style" of regulators

Voltage regulators

Voltage regulators


The top image is for a single phase 20 amp rectifier regulator, their model number is SH711. The bottom image is a three phase rectifier regulator, the table shows the ratings.

As can be seen, the components are very similar to the Podtronic style, the difference is instead of shorting the inputs (SCRs on) when the battery voltage gets too high, the SCRs are turned on when the battery voltage is too low and they are turned OFF when the voltage gets too high. When an SCR is turned on, it remains on until the voltage is reversed biased, so the battery will get full alternator voltage for one half cycle when the SCR truns on, this happens very fast so the battery will smooth out these pulses. All this means is less stress on the alternator, less heat in the alternator, less heat in the regulator.

The great thing is the price, see http://www.ebay.com/itm/Regulator-4-YAM ... d5&vxp=mtr this is barely more than a shorting type of regulator which makes perfect sense because it doesn't use more components than the P type. I have one on order and when I get it, I will test it and report back.

Jean
 
The magic happens within that little rectangle labeled "control"

(proprietary stuff)
 
A few models of modern Triumphs seem to have the occasional difficulty with their regulator/rectifier.
A popular choice for replacement is a Shindengen with mosfets from a Yamaha. Is the one you list the same?
 
nickguzzi said:
A few models of modern Triumphs seem to have the occasional difficulty with their regulator/rectifier.
A popular choice for replacement is a Shindengen with mosfets from a Yamaha. Is the one you list the same?
Click to expand...

No, mosfet rectifier regulators work the same as SCR type reculators when they are the "shorting type" or "shunt type" Shindengen makes all three types of regulators, SCR shorting (shunt), Mosfet shorting (shunt) and SCR series, only the last type does not load the alternator as a means of regulation.

Jean
 
Jeandr said:
bluemax said:
Jean,
Permanent magnet alternators are basic/simple in operation. They are not capable of maintaining any voltage level, they have no way of varying the magnetic flux as in the field winding of a car alternator. With no load (open circuit) they will produce a higher voltage at no current (no power produced) and at shorted input zero volts at maximum current be it limited by the available magnetic flux (again no power produced). There will be a sweet spot where the coils will produce the maximum designed power, somewhere between O/C and S/C. The zener will conduct at its designed voltage and effectively by its avalanche effect represent a short to the coil and rectifier. Equilibrium will be reached at the zener voltage and the current the zener draws at this point is the maximum design current. The whole system runs at full current all the time and the available current is shared by the load and the zener. This is probably why people report connector issues. Any connector resistance at this constant current will causes heating and melting over time irrespective of load levels.
The zener type regulator has full wave rectified A/C and is filtered by the capacitor if fitted and certainly by the battery applied to it to give a DC level. This DC is clamped by the zener to provide the regulated voltage. The zener will get warm when no load or light load and cooler with high loads.
The Podtronic type does the clamping or shorting of the coils in the legs of the bridge rectifier. In this configuration the Scr's would run cooler as they are not conducting all the time.

The point I was making about Lithium batteries was that they are capable of significant current at voltages above the zener clamping voltage and the system runs a risk of destroying the zener or electronic regulator as there is no limiting of this back current.

The whole system is a shunt regulator and by definition shunts the current to provide the required regulation voltage. The current is either shunted to ground or consumed by the load or both, but the current is always maximum. Properly designed coils and suitable wire thickness will have no issues running at maximum current.

Switching regulators are another kettle of fish and require unique switching design and snubbers to prevent back EMF when switching the coils out of circuit.

Cheers
Peter R
Click to expand...

Peter, the magnetic field from permanent magnets or the one induced from another coil like in a transformer act the same way. If a transformer or an alternator is built to provide a certain power, they choose the number of turns for the voltage and size the wires to provide the current it is designed for. If I take a 250 watt transformer giving 12 volts, it can pump out 20 amps, the windings on the secondary are probably 12 ga and the primary 26 ga. If the primary is built with smaller wire and I short the output, the primary will most likely burn up, the same holds true for the secondary, if it is undersized and the output is shorted, then IT will burn up.

While it doesn't happen everyday, alternators do burn up and the most likely reason is a shorted output, this could happen if the rectifier blows and shorts out or the wires rub on a metalic piece and short out or a careless owner squeezes that cover tighter to stop an oil leak caused by the wires in the way, that does happen. If the alternator was designed to run with shorted outputs, all would be fine except they use the smallest wire they can get away within the designed power output, they know for sure there will be a load on it, light bulbs, ignitions, horn... they never thought a lazy regulator designer woul think of shorting the alternator as a means of regulation.

I have asked an alternator maker if running for a long time with shorted outputs is within the design parameters, I suspect it is not but I will surely take all the feet I have in my mouth out if it is so.

The thing with lithium batteries is that they will gladly let the voltage go higher than a lead acid battery, when they do that, they allow a Podtronic type of regulator to camp the input sooner in the cycle so the alternator spends more time with a shorted output than it does with a lead acid battery.

That's the way I see it

Jean
Click to expand...
Jean we are not talking transformers with primary and secondary windings. Our Norton alternators are single coils construction and if made with the correct wire gauge IE low winding resistance they will happily run at their maximum current , if not its poor design regarding wire gauge.

The only cause of heat when it is shorted will be the coil resistance. This coils resistance is there weather it is delivering current or not.
A correctly designed coil will happily supply the constant current the regulator/load consume. As these alternators are a relatively high supply impedance and hence current limited (compared to a battery or the power grid generator) the fault current will be close to the operating current then trying to draw more current will only cause the voltage will drop. However the fault current of a low impedance supply could be enormous, try putting a nail in the wall socket.
Another example of a current limited device is a solar panel it is almost impossible to distinguish between normal maximum current and fault currents and in both cases the panel is happy to operate in this mode without burning up.
A bell curve of voltage verses current will produce a distribution of 0 watts when open circuit through the sweet spot of the bell curve where the maximum power is produced (designed operating point) to short circuit where 0 watts are produced. The only power produced at short circuit is the current flowing through the winding resistance. If designed properly the coil resistance will be very low and the resultant power and heat will also be very low.

I think at this point we will both have to agree to disagree.

Cheers
Peter
 
bluemax said:
Jean we are not talking transformers with primary and secondary windings. Our Norton alternators are single coils construction and if made with the correct wire gauge IE low winding resistance they will happily run at their maximum current , if not its poor design regarding wire gauge.

The only cause of heat when it is shorted will be the coil resistance. This coils resistance is there weather it is delivering current or not.
A correctly designed coil will happily supply the constant current the regulator/load consume. As these alternators are a relatively high supply impedance and hence current limited (compared to a battery or the power grid generator) the fault current will be close to the operating current then trying to draw more current will only cause the voltage will drop. However the fault current of a low impedance supply could be enormous, try putting a nail in the wall socket.
Another example of a current limited device is a solar panel it is almost impossible to distinguish between normal maximum current and fault currents and in both cases the panel is happy to operate in this mode without burning up.
A bell curve of voltage verses current will produce a distribution of 0 watts when open circuit through the sweet spot of the bell curve where the maximum power is produced (designed operating point) to short circuit where 0 watts are produced. The only power produced at short circuit is the current flowing through the winding resistance. If designed properly the coil resistance will be very low and the resultant power and heat will also be very low.

I think at this point we will both have to agree to disagree.

Cheers
Peter
Click to expand...

You are right when you say that with an open circuit, 0 watts is produced, but with a short at the output, the situation changes, true zero watts can be extracted electricaly, but the alternator is working against itself and producing heat in the windings that will eventualy destroy it UNLESS it was designed to be run like that forever. Utility power alternators are designed that way because the load they have to carry is so close to zero, our bike alternators are designed to support a short circuit for a certain lenght of time, but not forever and I wold guess the certain lenght of time is not calculated in hours but rather minutes and not many of those either.

I'm sure the design team at Lucas tested their alternator at full rating for hours on end and they must have had a spec for how long it could be shorted without damage, the same goes with the Zener, it was tested to take full alternator current at running RPMs to simulate the loss of a load with the engine running, for example just the ignition but no lights. The proper way to use a Zener is to feed it a certain amount of current, so there is always a resistance in the path, on our bikes, there is no resistance, only the internal resistance of the alternator and the resistance of the wires feeding it.

At any rate, I know the Podtronic and similar rectifier/regulators is not an elegant design, I'm not saying they don't work, but I will never put one on my bike. In some situations, they could accelerate the failure rate of the alternator, especially if the load is reduced by replacing incandescent bulbs with LEDs.

I do agreee to disagree with you :D

Jean
 
850dunstall said:
Jeandr said:
The great thing is the price, see http://www.ebay.com/itm/Regulator-4-YAM ... d5&vxp=mtr this is barely more than a shorting type of regulator which makes perfect sense because it doesn't use more components than the P type. I have one on order and when I get it, I will test it and report back.

Jean
Click to expand...

Jean did you get the unit and have you tested it, i assume you ordered the SH711.
Click to expand...

Yep, ordered that, but it is not what I expected, the information I had was wrong. That regulator is just the same as a Podtronic, it is a shorting type, 3 phase. The one that IS different, is this one http://www.ebay.com/itm/251849821753?_t ... EBIDX%3AIT that regulator is made from the same components as the other ones, but it regulates by allowing alternator voltage through when the output is below the regulation point and it opens when the output voltage goes above the treshold. I bought one so I can do measurements and will post my findings soon.

Jean
 
okay, my thought since the sh775 is a 3ph unit, would it work when connected to a single ph alternator, or does it depend on balanced 3 legs?
 
850dunstall said:
okay, my thought since the sh775 is a 3ph unit, would it work when connected to a single ph alternator, or does it depend on balanced 3 legs?
Click to expand...

Works just as well on single phase 8)

Jean
 
I ordered a Shindengen SH775 from this guy on eBay http://www.ebay.com/itm/251849821753?_t ... EBIDX%3AIT

It IS more expensive than the shorting type, but it performs way above the others.

So as before, first tap of my transformer:

AC Amps 1.2 A AC volts 13.5 DC volts at the battery with no load 14.4

This waveshape is on the AC side, the red line is current and the green line is voltage. As can be seen , the regulator turns ON to pulse the battery with a current spike.

Voltage regulators


And this wave shape is what the battery sees with a 2 ohm load (6 amps) The average voltage is a bit below 13 volts

Voltage regulators


Going to the next tap:

AC Amps 1.7 A AC volts 16.1 DC volts at the battery with no load 14.5

With a higher voltage, the regulator does not need to turn on as often

Voltage regulators


And this is what the battery sees with a 2ohm load:

Voltage regulators


Last tap,

AC Amps 2.0 A AC volts 19.0 DC volts at the battery with no load 14.58

Again, with higher voltage, the regulator turns on even less

Voltage regulators


And the battery sees with the same 2 ohm load:

Voltage regulators


This regulator is very "kind" to the alternator, it does NOT short out the windings so this means less stress on the alternator, the wires and all the connectors leading to the alternator. More expensive, but if it saves an alternator, it is worth every penny.

Jean
 
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